What Impacts Should You Expect From Hurricane Florence?

Hurricane Florence underwent rapid intensification last night and today and currently has maximum sustained winds of 140 mph. This puts Florence at category 4 strength, and expectations are that further strengthening will occur, given the favorable environmental conditions. It appears that Florence’s strength has currently leveled off for the time being, and with hurricanes of this strength, it is not uncommon for an eyewall replacement cycle to occur. This occurs when an outer eyewall begins to form around the original eyewall. Over time, the new eyewall eventually replaces the old one. Although this can result in temporary weakening, the storm can later strengthen further, and the wind field usually increases in diameter. We will have to see if that occurs overnight tonight or tomorrow.

In this article, I want to focus mostly on impacts, instead of going into a lot of detailed meteorology as I often do in my discussions. Below, I have included several questions that many of you have asked, and I am going to do my best to answer those.

Where is Hurricane Florence going to make landfall?

We’ve managed to get a better handle on where Florence is going, even though there are still some disagreements in the forecast model guidance. That’s normal though! Previously, we outlined a region from the northern Florida coast through the Carolinas. That zone can now be narrowed down a bit further. The region that should watch for a potential landfall extends from Charleston, SC to the northern coast of North Carolina. The latest several runs of the operational European model have consistently projected a landfall around the South Carolina/North Carolina border, and the ensemble means have shown a similar picture, maybe a hair farther south. Even though locations as far south as Charleston is out of the National Hurricane Center’s cone of uncertainty, I want to watch this storm for another 12 hours before taking that location out of the threat zone, especially since Florence has continued to maintain a westward to west northwestward trajectory. As ridging begins to build and strengthen to Florence’s north, we’ll see if it begins on a more northwest trajectory tomorrow.

Hurricane Florence forecast

Hurricane-force winds will extend well-inland from the center of the storm and along areas to the east of the center. Florence is going to slow down significantly as it approaches land; meaning, this may put somewhat of a limit on just how far inland hurricane-force wind gusts will extend. If the storm were booking it, it would cover a lot of real estate before weakening. In this case, hurricane-force winds may ultimately occur over less real estate, compared to a Hugo-type storm, BUT the wind damage that occurs within the first 24-hours of Florence’s landfall could very well reach catastrophic levels. Given that even a small margin of error in track could change the region that will have those kinds of winds, I recommend erring on the side of caution and preparing, especially if you’re on the Carolina coastline and within 100 miles of the coast.

Hurricane Florence winds

How much flooding will Florence produce, and how widespread will it be?

If Florence makes landfall where it is currently projected, flooding could be widespread and deadly, well away from the storm’s center. Air will be forced upward by the mountainous terrain on the eastern side of Florence, something referred to as orographic lift. This means that rainfall rates could be a bit higher compared to a region that has a hurricane moving over flat terrain. Remember, Harvey was a prolific rain producer because it stalled for days. There will be other factors at play that could enhance Florence’s total rainfall amounts; thus less time will be needed for heavy rainfall totals to occur.

In no way do I want to undermine the wind threat. It’s going to be bad! But, I always take flooding very seriously on Firsthand Weather, especially when I see that it’s going to be a widespread event such as this one. Below, I included an image that shows the Weather Prediction Center’s current projected rainfall totals that will be associated with Florence. As you can see, widespread areas of 10 to 15 inches of rain is expected across North Carolina and Virginia. Many of those locations have already received a lot of rainfall this summer, even recently. I think these totals could be a bit underdone in some places, so assume that there will be regions that could well-exceed above 10 to 15 inch rainfall totals.

Hurricane Florence rainfall

Will Storm Surge Be A Big Threat?

The short answer is. . .yes!! For residents along and near the coast, storm surge will be a major issue on the east side of Florence. This is a deadly threat that is often not taken seriously. Even a very small change in track could alter the regions that will get the highest storm surge.

Hurricane Florence storm surge

Some Advice:

If you are under mandatory evacuations, I strongly urge you to evacuate. There will be some of you who will evacuate and may come to realize by the end of all of this that it wasn’t necessary. However, you don’t want to find yourself in a situation wishing that you had left. You may be putting yourself and your family at risk. It’s generally a good idea to expect the unexpected. When do meteorologists ever get a forecast completely accurate, especially one like this? Never. That’s not a criticism of the science, but instead, it’s something that you should take into consideration. It’s best to plan for unexpected changes in track and intensity that weren’t necessary predicted by professional meteorologists. It’s the nature of the science, and it’s one you should be aware of, especially if you are tempted to believe your area may not be a high-impact area.

If you are unable to evacuate, whether that’s due to financial reasons or whatever else, try to reach out to those who are willing to help. Many of our followers on Firsthand Weather have been providing tips, making others aware of resources that they weren’t aware of, and even offering their homes for free for others to stay. Please go to the Firsthand Weather Facebook page, and we will do our best to guide you to the great amount of information that many of our followers have already provided.

What are the odds that Hurricane Florence will actually hit the East Coast?

As of 5 pm AST, Florence is a category 1 hurricane with maximum sustained winds of 85 mph. Over the last several days, Florence has raised some concerns given that forecast model guidance has oscillated back and forth between an East Coast impact and an out-to-sea solution. Most of the model guidance has really struggled with where Florence will be positioned beyond 5 days. Ridging has persisted across the eastern U.S. and extends just off the East Coast, and by late weekend to early next week, a trough is going to begin moving across the northwest Atlantic, while ridging will remain parked across the southeastern U.S. and extend off the southeast coast.

Since Bermuda ridging is not well-established across the central North Atlantic, Florence should continue gaining latitude over the next several days. However, if Florence were to weaken quite a bit in the short to medium-range, there is the possibility that it could have a more westward component to its track in the coming days. The concern has been that if Florence moves on a more westward track, that it could sneak under the ridge instead of getting picked up by the trough, which would steer the system towards the East Coast. Yes, I can’t discount that possibility, but I think that it is the least likely scenario.

Hurricane florence track scenarios

I made a graphic that shows tropical cyclones since the 1800s that have tracked very close to the current 5-day projected path of Hurricane Florence. If a tropical cyclone tracked within 2 degrees of Florence’s current position and within 4 degrees of its predicted position at days 4 and 5, its track was plotted as a red line. The black dots represent the National Hurricane Center’s current track forecast for Florence. Even previous systems that tracked a bit to the south of the NHC’s forecasted position for Florence on days 4 and 5 eventually curved northward and went out to sea. Out of the 71 cases selected, none hit the East Coast, and only one impacted the U.S. In other words, if history is any indication of what will happen with Florence, it needs to remain considerable farther to the south in the coming days than what is currently being predicted for the probability of an East Coast impact to increase.

Tracks similar to Hurricane Florence

Physically, the two scenarios are plausible; thus, the East Coast needs to continue to monitor closely. However, with all things considered, Firsthand Weather is currently leaning quite heavily towards the out-to-sea solution. Yes, we could be wrong, since predicting the projected path of a tropical system in the middle of the Atlantic beyond 5 days is very challenging. Please continue to check back with us on the website and on Facebook/Twitter on a daily basis in case anything changes.

Hurricane Irma Should Be Monitored For Possible U.S. Impacts This Weekend/Next Week

As of 8 pm ET, Hurricane Irma is still a strong category 5 hurricane with maximum sustained winds of 185 and gusts up to 225 mph. It has unbelievably maintained that same strength since yesterday, despite some fluctuations in minimum central pressure. It is moving west-northwest at 16 mph and will be skirting the northern coast of Puerto Rico soon.

Forecast Discussion:

The biggest challenge to forecasting Hurricane Irma’s track through early next week remains the various features that either have or will impact its steering. Bermuda ridging over the Atlantic has kept Irma on a westward course, and this feature will continue to play a role on Irma’s movement. This ridge has strengthened and has even built southwestward with time; however, there are two main features to watch that could act to break down the westward extend of the ridge closer to the end of the week.

First, a longwave trough has established itself over the eastern United States with a ridge back to the west. For what it’s worth, this is actually the pattern that is responsible for bringing less humid and cooler air across the eastern half of the United States. Unfortunately, it appears that the trough is going to move out too quickly for it to actually steer Irma safely away from the U.S. east coast; however, as the trough lifts and then propagates eastward with time, it will keep a weakness established between the Bermuda ridge out east and a ridge that will center itself over the Four Corners region and extend into west Texas by this weekend. Once Irma gets far enough west, this should result in Irma taking a hard turn northward. This is actually well-advertised in the model guidance, but there has been a bit of spread over the last few days between the models on when that northward turn will occur. Some models take Irma into the eastern Gulf of Mexico, some northward through the peninsula of Florida, and some skirting Florida along its east coast before taking Irma into Georgia and South Carolina.

latest irma forecast models

Figure 1: This is the latest model representations of where Irma could go.

Although Bermuda ridging may build southwestward over the next day or two, this feature should become less of a dominant steering mechanism at least long enough for Irma to start making the turn northwestward/northward towards the end of the week or early weekend. The second feature to watch will be Hurricane Jose. It’s difficult to say if that will have any influence on the southern extent of the Bermuda ridge as Jose treks in a northwestward direction, but it’s most certainly something to watch closely.

To complicate matters even further, the current ridge that is established over the western U.S. which extends northward into western Canada is going to actually break (imagine a wave in the ocean crashing), which will result in the formation of a cut-off low (the same trough I was referring to earlier). Another, weaker shortwave will be moving southeastward towards Mississippi and Alabama, and ridging may begin building over the northeast by this weekend. All in all, this continues to be a super complex forecast.

Aside from all of these features to monitor, the angle that Irma will be coming in relative to the coast makes for additional challenges. A jog fifty miles west or east can be the difference between major hurricane-force winds along the coast or barely tropical depression/storm-force winds.

Where I Think Irma Could Go And Who Should Be Preparing:

Now that you’ve listened to me spend quite a lot of time talking about the complexity of this forecast, I’m actually going to attempt to make a forecast. We still have the three scenarios on the table that I presented close to a week ago in my earlier articles. Irma could barely make it into the eastern Gulf of Mexico and ride along Florida’s west coast, Irma could ride up or along the eastern Florida peninsula into Georgia or the Carolinas, OR Irma could move just east of Florida and out to sea.

The least likely scenario is for this system to go into the eastern Gulf of Mexico. While Bermuda ridging will certainly continue to influence Irma’s steering, it likely won’t extend far enough westward. With a weakness established between the two ridges and with the possible influence of the eastern U.S. trough (even with it lifting out), this should open the door for Irma to make that turn northwestward and then northward before getting into the Gulf. There was quite a bit of talk in the meteorological community about how if Irma stayed below a certain latitude that it would increase the odds of an entrance into the Gulf, and while that may be true, Irma should gain enough latitude over the next couple of days for this scenario not to unfold. I still advise those along the Florida panhandle and west coast of Florida to closely monitor the latest forecasts regardless, due to the complexity of the forecast.

irma sea surface temperatures

Figure 2: Hurricane Irma remains over warm waters.

Based on what I am seeing, the most likely scenario is for Irma to make the turn northwestward and eventually northward before reaching the Florida Keys. This would result in Irma riding along the Florida east coast, possibly causing tropical storm to hurricane-force winds for regions closer to the coast. It’s too soon to say if these winds will be tropical storm/low-end hurricane strength or closer to major hurricane-force winds. I’m not saying that because I’m predicting Irma to weaken considerably before reaching coastal regions of Florida, but because a slight difference in track west or east will make a significant difference in impact. That’s why all residents from the Keys to the east coast of Florida need to prepare for this event. Also, residents located in the Bahamas need to prepare to possibly be impacted by a major hurricane.

As Irma rides close to the coasts of Florida and Georgia, the upper-level low over the Southeast, the ridging over the Northeast, and the Bermuda ridge could cause Irma to eventually make a landfall somewhere between the north Georgia or South Carolina coasts. The strength of these features will ultimately play a role in how this evolves. Residents along the Georgia and Carolina coastlines (including North Carolina) need to monitor this situation very closely, and if model guidance begins to consistently support this forecast and the reasoning behind it, vacation plans for late this weekend and early next week will need to be canceled.

Irma Impact Map

Figure 3: These are states that could be impacted by Hurricane Irma. Note: the black line represents the NHC’s latest projected path; however, the buffer around the black line is not the NHC’s cone of uncertainty, just a 2 degree buffer.

Bullet-Point Summary:

  • The Bahamas need to prepare to potentially be impacted by a major hurricane. The Florida Keys to the east coast of Florida could be impacted by tropical storm to hurricane-force winds. A fifty-mile difference in track could result in huge differences in impact. Given that we’re about five days before Irma reaches Florida, it’s too soon to make a forecast with that kind of precision, given Irma will trek parallel to the state. In fact, it actually could prove to be a challenging forecast even 24 to 48 hours beforehand.
  • While it can’t be ruled out that Hurricane Irma will go into the eastern Gulf of Mexico, it’s highly unlikely. Residents from the panhandle to the west coast of Florida still need to be aware of the latest forecasts in case anything changes.
  • Residents along and inland from the Georgia and Carolina coasts need to prepare to possibly be impacted by a hurricane very late weekend into early next week. While it should be understood that this forecast remains to be complex, planning for this event should be ongoing.
  • While some weakening could occur, Irma is expected to remain in an environment that will support little weakening through at least the end of the week. It seems unlikely that Hispaniola will majorly impact Irma’s strength.
  • We will address other states that could be impacted by Irma over the next day or two.
  • Again, as has been stated numerous times, this forecast is complicated. Modifications will have to be made, but there is nothing wrong with preparing for this event, despite the uncertainty that remains.

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Hurricane Safety and Quick Tropical Update

Hurricane Hunter aircraft are once again in the air this afternoon exploring Hurricane Irma. Yesterday evening, the NOAA and US Air Force put on a display with 4 flights into Irma to gather data. At the moment, there is currently 1 flight under way, an upper level dropsonde mission, but 1 low level recon mission has just completed with more preparing to get under way. Hurricane Warnings are in effect for several of the Caribbean Islands and a very dangerous situation will be occurring there in the next 24 hours. Hurricane watches have been extended to the Turks and Caikos and Southern Bahamas. Irma still has winds of 185 miles per hour with gusts over 220 miles per hour.

Tropical Storm Jose has formed to the East of Irma in the Atlantic. This storm is expected to become a hurricane to be just east of where Irma presently is in about 3 days but the forecast calls for it to move to the Northwest and be less of a threat to the Leeward Islands.

Tropical Depression 13 has formed in the Gulf of Mexico. This is expected to become Tropical Storm Katia in the next couple of days. This system does not appear to be a threat to Texas and will actually loop around to the south and hit Mexico at this time. We will obviously watch this situation carefully.

The track below are Irma, Jose and 13 respectively.

Hurricane

Hurricane Safety

Evacuations

Evacuation orders are being prepared for in the Florida Keys currently. For those who are evacuating, you will need to determine a safe evacuation route inland and as far north as you can get. While evacuating, you’ll want to monitor the latest information to ensure that you will be evacuating to a location that is not also under a risk. Public services in these areas will already be strained and adding many evacuees will only cause more strain for everyone. Learning the location of official shelters will be helpful both in the event that you evacuate as well as for those who do not evacuate. Areas that are not under evacuation orders should also have shelters for the residents who end up in trouble due to hurricane hazards. Tornadoes, lightning, power outages, and property damage due to falling trees can force residents from their homes, even if a mass evacuation isn’t needed.
When evacuating, put together a go-bag. Include a disaster supply kit, including a flashlight, batteries, cash, first aid supplies, medications, and copies of your critical information if you need to evacuate. Ensure that you secure your critical information in waterproof bags. Snacks and stuff to drink will also be good for longer evacuations, especially with children and pets. While you may stop for gas, many others are also evacuating with you so its possible that many supplies will be sold out along your route. If you haven’t already, fill up your gas tank in your local area. Cell phones should be charged before you leave. Have one member of your family turn their phone off while travelling together. This will ensure that if one phone does run out of battery, you will have another phone to turn on and use. All family members should have all numbers for your phones and know to call multiple numbers if they can’t get a hold of you.
You should also inform someone of your plans. If you fail to arrive at your destination due to a car accident, your contact can alert the authorities. Having them know the route you planned to take is essential in locating you.
Stay tuned to local news outlets as you travel. Conditions may change and areas you were heading to that were going to be safe may not be anymore. Harvey brought a large area of rain to Texas and some locations people were heading for wound up under a flood warning when it wasn’t before. Always ensure that the safety of your location is the top priority.

Staying at home

For those of you who are not leaving home, I would first implore you to heed local evacuations if you are under them. Evacuation orders are given for a reason. If you are under those orders it is absolutely not safe where you are. While I do realize that some properties remain even in massively damaged areas, you only put yourself and those who would need to rescue you in the event of an emergency in danger by taking that gamble. It is never just your survival on the line.
If you have not been ordered to evacuate, there are several things you should plan for. First, as I mentioned above, have a plan to be able to evacuate to a local shelter if your house if one of the unfortunate locations that falls victim to one of the more local hurricane hazards. Lighting occurs frequently within a hurricane and can strike even in areas where hurricane conditions are not occurring. You should also have a plan for any pets you may have. Not all shelters accept pets so ensure the one you may go to does.

What to bring to the shelter

You will need to make sure that you have everything you need at the shelter. While the shelter will have supplies, they don’t usually carry specific medications or your specific brand of baby food or pet food. Ensure that you have a first aid kit with all the medications taken by your family. If you are running low, see if your local pharmacy can give you more. Baby food and diapers will be needed. Your baby should be prepared for a multiple day stay at the shelter. Bring things to do as well. Books, games for children, headphones and a source of music (we all know some of you still have a Walkman) will all be desired. The shelter is not exactly a fun place to be. Bring your toiletries and blankets. The shelter will have some but we all prefer our own. Flashlights and batteries are good to have in case the power goes out at the shelter as well. Also ensure you bring identification, cash and credit cards as well as copies of your essential documentation like proof of insurance.

Protecting your home

Be aware that Hurricane winds can cause trees and branches to fall, so before a hurricane trim or remove damaged trees and limbs to keep you and your property safe.
Secure loose rain gutters and downspouts and clear any clogged areas or debris to prevent water damage to your property. This can also help keep them lighter and not fall under the weight of all the rain. Hurricanes can be a daunting experience for a lot of people and if you decide to stay in your home, you need to make sure that all of the exterior systems like your guttering are working efficiently. Too much water in your gutters can increase the chances of water damage, which can result in further problems that you don’t need. By contacting someone similar to this Clean Pro Gutter Cleaning Baltimore company regularly can help to make sure that your gutter is free from anything that could have an impact on how it works, especially in the event of a hurricane. Reduce property damage by retrofitting to secure and reinforce the roof, windows and doors, including the garage doors. Plywood over windows or close storm shutters if your house has them, this can protect them from wind and debris. If you are construction inclined, hurricane clips can be installed in your attic to help secure your roof to the house. You can also brace your garage door and doors that lead outside with planks to keep it from blowing in. You should also close all interior doors to compartmentalize the house. If your doors sustain any damage remember to contact a company like Spark Garage Doors – Repair & Installation straight away. This way, if a window does break in one area, the remaining areas will have protection against the elements coming in. Purchasing a portable generator or installing a generator for use during power outages is also a good idea. Remember to keep generators and other alternate power/heat sources outside, at least 20 feet away from windows and doors and protected from moisture. You should never try to power the house wiring by plugging a generator into a wall outlet. If power does go out, use a flashlight. Candles are a fire hazard.

Keeping food and water safe

The most important thing when it comes to food is to buy nonperishable goods and to store water. You do not need to buy multiple gallons of water for activities like brushing your teeth. Simply refill an old milk or water bottle with tap water and use it. You can do the same thing for bath water, pre-filling your tub is also recommended. Tap water storage can be done with any container from large pots used for cooking to old bottles and even any large plastic container. Always remember to keep using the tap water until it goes out, you don’t want to needlessly use up your supply and not be able to replenish it. For any cold food you do have, turn your refrigerator and freezer to their maximum cold settings and open them as little as possible. This will help keep things cold. Try to use up any chilled foods first so that keeping things cold becomes unnecessary and have a supply of ice on hand to keep things cold longer. While you can buy ice at the store, you can also just use ice cubes. Simply dump your tray into a plastic bag and refill the trays. Dump new ice cubes as they form and keep refilling the trays. You will be able to continue this process for as long as you have power or tap water. This also creates an emergency water supply should you run out of water. Simply melt the ice. You can also use rain water if you have a safe way to get a bucket outside to collect some. You should always try to keep a lid on your water supply. This will keep dust and bugs out of it.

After the Storm

It will be tempting to go outside after the storm has passed or during the calm period in the eye. This should be avoided. The eye is only temporary and hurricane conditions can start very quickly. After the storm, there will be a lot of damage in the region. Floods could still be occurring and the water could be contaminated. You also can’t see what’s in the water. Animals and hazards in the water could be potentially dangerous to your health. The water could even be electrically charged from downed power lines.
Even where roads are visible, bridges and roads may no longer be safe for the weight of a vehicle.
Once you are home, check for damage. Ensure there are no downed wires, water or gas leaks, or damaged appliances in the home. Make sure you get Water Damage and Roofing Austin to repair any damages ASAP to prevent further issues.
We here at Firsthand will do our utmost to keep you up to date with the latest information. Our thoughts go out to those in the areas affected by Harvey. Stay safe everyone.

Robert Millette
Incident Meteorologist
Braintree Emergency Management Agency

Everything You Need To Know About Hurricane Irma

We continue to have a very complex forecast on our hands with Hurricane Irma, and while we do have some time to nail down the forecast, it’s understandable that residents along the East Coast and even along the eastern Gulf of Mexico are wanting to know what plans they should be making in preparation for Irma. Tonight’s article will not be particularly long and detailed, but I do briefly want to point out few things.

As of 8 pm ET, Hurricane Irma is a category 4 hurricane with sustained winds of 120 mph. Irma’s movement is finally back to the west after losing some latitude due to the influence of an upper-level low to the northeast of the system. Bermuda ridging should strengthen in the coming days to the north of Irma and could even build southwest, which will keep system generally on a westward track. Regions, across the northern Lesser Antilles and the Greater Antilles, including Puerto Rico, Haiti, Dominican Republic, and Cuba need to prepare to be impacted by a major hurricane. I have included the National Hurricane Center’s latest five-day forecast, and residents in those regions need to understand that a track just slightly farther to the south will worsen the possible impact from this storm. This could be a serious situation, so again, I urge residents of those islands to not take this threat lightly.

Hurricane Irma Track
Figure 1: The National Hurricane Center’s latest 5-Day forecast for Irma (as of 8 pm ET)

Unlike with Harvey when it first made landfall, Irma’s forecast is quite complex due to the angle that it will be coming towards the coast of the contiguous United States, which could result in a level of uncertainty remaining even by the end of the week or weekend. Additional complicating factors to this forecast include numerous features that will potentially be influencing the track of Irma, which will ultimately determine whether or not this system makes landfall in the U.S. In order to keep this forecast briefer than my last discussion, I’m going to provide a bullet-point list below. I will be providing a follow-up forecast either tomorrow night or Wednesday, depending on how things evolve over the next 18 to 24 hours.

Sea surface temperatures hurricane irma
Figure 2: Irma will continue moving westward into warm waters. The black dot represents Irma’s location as of 8 pm ET.

  • First and foremost, residents across the entire coast of Florida and along the East Coast need to start making some preliminary plans, just in case. In particular, I urge residents from the southern Florida coastline to the Carolina coast to begin making plans and to continue following the forecasts closely. I still can’t rule out this system making it into the far eastern Gulf of Mexico; however, it still remains unlikely. Residents along the western Gulf of Mexico coast do NOT need to worry at this time. If a U.S. landfall occurs, it likely won’t occur until this weekend, at the earliest!
  • A western ridge/eastern trough configuration is going to set up across the United States. If this pattern were to hold, this would allow Irma to safely recurve out to sea away from the U.S. However, this pattern is likely not going to hold long enough. The western ridge is probably going to break (imagine a wave crashing in the ocean), and while the trough could become cut-off from the main flow, it appears that it will move out to the northeast before Irma gets far enough northwest to be picked up. Ridging to the west will remain in place while Bermuda ridging will either build westward or remain in place. Between these two features, a weakness will still be present over the eastern U.S, which will eventually result in Irma taking a sharp turn to the north. The timing of this turn to the north will be everything. It will be the difference between this system going into the far eastward Gulf, through Florida, or impacting regions along the eastern coast of Florida and the Carolinas.
  • Again, this forecast is tricky also because of the angle Irma will be coming in relative to the United States. With Harvey, it moved mostly perpendicular to the coast towards Texas before making its first landfall, so we knew that somewhere along the Texas coast was going to be heavily impacted by hurricane-force winds. In Irma’s case, it will be coming in parallel to the coastline or if it starts making its northward turn south of Florida, it could come in perpendicular to the south Florida coastline (but remember, the southern Florida coastline is MUCH shorter in length than the Texas coastline).
  • At this point, I’m still not ruling out Irma only skirting the coastline or completely being a miss; however, that isn’t the most likely scenario. At this point, the most likely scenario is an impact to Florida, Georgia, and the Carolinas. Keep in mind that modifications to this forecast are likely, and that forecast confidence is much lower than usual.

Hopefully by Wednesday, we’ll get a much clearer picture of what could unfold. Just hang with us, and we’ll make sure we nail down this forecast for you as quickly as possible.

Keeping A Close Eye on Hurricane Irma

As of 5 pm ET, Hurricane Irma is a category 3 storm (115 mph sustained winds) located at 17.3° N and 34.8° W and is moving west northwest at 12 mph. Irma was only a tropical storm this morning but underwent rapid intensification. Irma has remained in a relatively low-shear environment; however, this kind of quick intensification was actually a bit surprising. While sea surface temperatures were above the threshold for tropical development (above 26°C/79°F) when Irma quickly intensified, these temperatures were not overly warm. While the National Hurricane Center has Irma strengthening further over the next day, I actually wouldn’t be surprised if there is some slight weakening or at the least, no additional strengthening for about a day. There is a bit of dry air out ahead of the system, and as I mentioned, sea surface temperatures are just above the threshold for development. Regardless, Irma will eventually move over much warmer sea surface temperatures (with higher ocean heat content), and given that vertical wind shear should remain light, there’s no reason that this system won’t rapidly intensify into a stronger hurricane, possibly reaching category 4 status over the next few days. To sum it up, after a brief break in strengthening, Irma should strengthen further. If it ends up wrecking homes near you, it might be a smart idea to talk to Ballwin Commercial Roofing Pros to better understand how to repair homes during the aftermath.

dry air hurricane irma

Figure 1: There is some dry air that Hurricane Irma could temporarily encounter.

We are going to be tracking Irma for a long time, which gives us a decent amount of time to figure out where Irma is going. Also, if Irma were to directly impact the contiguous U.S., it won’t be for at least 10 days, give or take a day. It could even be a bit longer. What I’m basically saying is NOT to cancel any plans just yet, but instead, follow the latest tropical updates very closely if you live near the coast or have vacation plans.

Hurricane Irma projected path

Figure 2: The National Hurricane Center’s 5-day projected path of Hurricane Irma

Hurricane Irma Discussion:

The big question over the next several days will be to determine if Irma could be a threat to the U.S. Along with a mid to upper-level low (northwest of Irma) to the south of the Bermuda ridge creating a weakness, numerous shortwave features will ride along the northern periphery of the Bermuda ridge, keeping this ridge on the weaker side over the coming days. In addition to this, the latest guidance indicates that a longwave trough could develop over the eastern U.S. next week. If at this point Irma were to be far enough west, then it would likely recurve and miss the East Coast. However, it appears that the eastern trough will move out in time, and Bermuda high pressure will build westward, possibly extending along the East Coast. This would increase the threat of Irma eventually impacting the East Coast, but also, some guidance builds the Bermuda ridge far enough west and southward that Irma slides between Florida and Cuba into the Gulf of Mexico. At this point, there are a plethora of scenarios, but two of several things to watch closely will be the strength of the Bermuda ridge and how long the longwave trough remains established over the eastern U.S.

If you’re going to follow the forecast models, don’t actually be too focused on where the models show Irma going at this point. The model guidance will continue to vary quite a bit on exact track, so as stated above, the focus should be on the following two features: the strength of the Bermuda ridge and the longwave trough that will be building over the eastern U.S. Also, keep a close eye on how far north Irma gets over the next several days, because a more northward track increases the odds of either impact to the East Coast OR a recurvature out to sea. If the trough fully moves out and Bermuda ridging builds westward quickly enough, then we potentially have a problem in the Gulf of Mexico.

From the looks of it, Typhoon Sanvu in the western Pacific may play a major role in influencing the downstream pattern over the U.S. in about a week. Sanvu is going to gain latitude with time and make an extra-tropical transition as it gets absorbed into the westerlies. Recurving typhoons in the western Pacific can sometimes cause the jet stream to buckle as excess amounts of latent heat gets transferred to the atmosphere, resulting in a wavy jet stream downstream over the U.S. I suspect this is the cause of the western ridge/eastern trough pattern that will evolve over time, and while this would be a great pattern for steering hurricanes away from the U.S. (assuming the hurricane remains high enough in latitude), the forecast model guidance just doesn’t have this pattern sticking around long enough. Some models lift the trough out quickly but leave a piece of energy behind over the southern U.S., and some fully lift out the trough. The problem is that as soon as this trough moves out, the Bermuda ridge will most likely build westward and become well-established. That’s what we don’t need to happen.

Jet stream hurricane irma

Figure 3: Model guidance shows a western ridge/eastern trough configuration over the U.S. next week.

Bullet Point Summary Of “Stuff” To Watch Over The Next 5 to 7 Days:

  • Watch the strength of the Bermuda ridge and see how the upper level low to the south and extra-tropical systems to the north influence its strength.
  • Watch to see if Irma gains some latitude, given that any amount of latitude gain could increase the chance of an East Coast impact OR a recurvature out to sea.
  • Watch the building trough over the eastern U.S. and see how quickly or slowly it will be moving out of the region.
  • Watch how Typhoon Sanvu influences the downstream pattern in about a week, given that this will probably be the culprit behind the western ridge/eastern trough configuration
  • Understand that models have a difficult time handling such meridional flows (wavy jet stream patterns). Throw a hurricane into the mix, and it gets very complicated.
  • Don’t really bother looking at where the models have Irma going beyond 4 to 5 days at this point in time. Focus on the above bullet points for now.

If you read this article and have come to the conclusion that we have no clue what’s going to occur, then, to an extent, you’d be correct. I could wait several days to write these articles until there is a bit more certainty, but I like to go ahead and introduce the Firsthand Weather audience to what I’m actually watching. I will be referring to features such as the Bermuda ridge, the eastern trough, etc. over the next week to two weeks, so I wanted to go ahead and give everyone a very early introduction to what’s going on. It will only make the forecast better over time and will help all of you with your planning for this potential hurricane.

Hurricane Matthew and Everything You Need To Know

Hurricane Matthew projected path

Hurricane Matthew continues to be just a phenomenal storm from a meteorological perspective; however, as many well know, tropical systems such as Matthew can have a huge impact on the lives’ of many people. In this article, I mainly want to address two main topics: where will Matthew track and what will the impacts be to the United States.

In order to do that, I want to set this up by taking a look at the overall pattern that is going to ultimately steer Matthew, and this will lead into the forecast, where I’ll discuss potential impacts. This is something that I discussed over a week ago on Facebook, and given the synoptic pattern, it was discussed why it was not wise to rely on forecast models. That has shown to be true since models have now trended westward with Matthew’s track with time.

The Bermuda Ridge Telling Matthew Where’s He’s Going To Go:

Many located across the Southeast and those located even along and extending westward from the East Coast in general have become very familiar with the Bermuda ridge this summer, which has been very much responsible for the awful heat and humid conditions that many have had to deal with. Instead of looking at every single model run of every single model, your best bet in nailing down the the track of Matthew is accurately predicting the placement, westward extent and strength of the Bermuda ridge. A stronger Bermuda ridge will lead to a more westward track. There is clockwise flow around a ridge feature such as this in the Northern Hemisphere, and since Matthew is on the westward side of that, the flow around that ridge will continue to pull him northward and even northwestward as he increases in latitude.

I want to give you a bit of a visual of this to go along with what was just explained. The image below shows the 48 hour trends in heights at the 500 mb on the GFS model. Now notice all of that red shading right along the East Coast, above and around where Matthew is located off the South Carolina coast. Simply put, this indicates that the GFS model has trended stronger with the Bermuda ridge, and the green circle around it indicates that this is statistically significant. Again, the strength and placement of this ridge will be one of main drivers that determines how this system will track, especially as Matthew moves along the Southeast coast. Nailing down how this ridge evolves with time is pivotal to this forecast! It’s important to note that models, including the European model, have made this westward trend also. If you’re like me and always skeptical of the forecast models, the expanding Bermuda ridge is not that surprising, given that this feature was strongly present this summer and Matthew slowed down enough to give the ridge enough time to build westward after the cut-off low moved out of the eastern U.S.

GFS trend map

Due to the westward trend, the National Hurricane Center has issued hurricane watches for parts of Florida, and I expect those watches to eventually be extended to the Carolina coast. The Georgia coast is always a tricky spot to nail down, but watches will probably be issued for those locations, too. Keep in mind that I DO NOT expect Matthew to go into the Gulf of Mexico. This is a threat for the East Coast, particularly the Southeast coast in the near-term (late week to this weekend).

Hurricane Matthew projected path

It Get’s More Complicated Once Matthew Moves Northward Thanks To A Gulf Of Alaska Trough Moving East:

In addition to the Bermuda ridge, a ridge extends up over New England into eastern Canada. This will likely keep Matthew slow-moving through the early weekend, but then things get interesting and even a bit more uncertain. A trough moving from the Gulf of Alaska will come eastward with time, but how quickly it moves east and how deep this trough digs will be a pivotal factor in determining where Matthew tracks beyond the Carolina coast. The latest European model has the ridge over the Northeast breaking down some, but it has the trough much weaker and having less of an influence on the system. The GFS model keeps the trough stronger farther east and has a bit more of an influence. This will be a big factor later in the weekend into early next week as to how Matthew impacts the Northeast, and by the way, I don’t buy the latest European’s solution of having Matthew looping along the Southeast. He eventually will make an extra-tropical transition as he interacts with a frontal system. Luckily, it is Tuesday, and we still time to nail down that part of the forecast, so I’ll have a separate update coming out on that!

Impacts, Sea Surface Temperatures, and More:

Florida will begin to feel the impacts of Matthew on Thursday, which will extend through most of Friday. Impacts will be felt along the Georgia and Carolina coasts this weekend. Prior to this, coastal and even inland locations will start to notice an increase in winds and rainy conditions.

This threat is two-fold. First, residents from the east coast of Florida (probably north of Miami) up through the Carolinas should prepare for hurricane-force winds. Keep in mind that this system is not coming in perpendicular to the coast but will be riding parallel to the coast. Instead of trying to pinpoint one location on the coast that could experience the highest winds, Matthew could produce a swath of hurricane force winds along an extended stretch of the coast. Hurricane track is EVERYTHING. If it moves a bit more eastward, the impacts won’t be as bad, but if it comes in as projected on a farther westward track, this is the worst case scenario. As I explained above, there is reason to believe, aside from the model guidance issues, that the Bermuda ridge will build westward. Prepare for this scenario, and don’t take this threat lightly. We will eventually be posting impact maps for all of this.

The second big threat will be flooding, and one that must not be overlooked. East coastal regions from Florida to Virginia could easily receive 6 to 10 inches of rain with many locations possibly going over a foot of rain. Inland locations away from the coast could also receive very high rainfall amounts. Beyond Virginia, the Mid-Atlantic and Northeast will have to watch for this threat closely, too. However, how much rain those regions receive is dependent on what Matthew does after impacting the Carolinas, which as explained above is one aspect of the forecast that I’m more uncertain about currently. Luckily, there is enough time to get that nailed down!

The below image shows that sea surface temperatures are above normal across all regions that Matthew will be moving across in the coming days. High pressure aloft will continue to help ventilating Matthew, and if Matthew happens to weaken at all between now and its passing near the Bahamas, rapid re-strengthening may occur. As a jet streak moves eastward with the trough, this actually could enhance ventilation as he moves up the coast.

SST anomalies in western Atlantic

On a final note, I realize that many of these hurricane forecasts have not verified over the years, but that doesn’t mean that you shouldn’t be prepared. As I mentioned, this is not a situation where a hurricane is approaching perpendicular to the coast and we’re trying to find the exact point it’ll hit. When hurricanes come parallel to the coast such as Matthew will, slight deviations in track changes the entire forecast in a major way. Realize that early on, and keep in mind that while technology has helped improved the quality of these forecasts over the years, hurricane forecasts where such small details can be the deal-breaker need to not be taken lightly. That’s my long way of saying, be prepared and hope this forecast doesn’t verify.

Firsthand Weather will continue to keep you updated throughout this event. There was much more that I could have covered, but we want to be careful about throwing too much information at you at once. Hopefully this article clears up any questions that you may have, and we will continue to monitor the situation at hand!

Hurricane Joaquin Forecast Is Complex, East Coast Needs To Monitor Closely

Joaquin Makes Landfall Along East Coast

Anytime you have the slightest possibility that a tropical storm or hurricane is going to impact the United States in any way, you’re going to hear about it all over the news media, social media, and everywhere else. In this case, it is good to get people prepared along the East Coast, but I want to break down what’s going on and show you why this forecast is complex. Hopefully this article clears up many of the questions that you may have, despite the current uncertainty.

Current Details On Hurricane Joaquin:

As of 8 pm ET, Hurricane Joaquin has 105 mph sustained winds and is moving to the southwest at 8 mph. A change in direction to the north should occur in a couple of days, but how quickly that occurs will be one of the determining factors as to whether or not this hurricane eventually hits the East Coast or turns northeast out to sea. Keep in mind that I said it’s one of the determining factors; there are other factors I’ll get into in a minute.

One Of Two Scenarios Could Play Out:

The region off the Southeast U.S. coast is the area that I have been monitoring most closely this season, and I even specifically talked about how that region would have a higher probability of seeing some tropical mischief this year. The waters are very warm, and given the right environmental conditions to go along with it, rapid development can occur. In other words, Hurricane Joaquin is in a favorable area for development so further intensification is likely.

When a tropical system develops into a hurricane, the mid and upper-level wind patterns have a much bigger influence on the path the storm takes. This isn’t as much the case with a weaker tropical system. I generally look at the 500 mb pressure level (which is approximately 18,000 ft above the surface) to try to determine where a hurricane like Joaquin will be steered. It seems like a simple concept, but you have to know where your troughs/ridges are going to be located and the timeframe. Also, you have to know when and how much these wind patterns will influence the storm. If this doesn’t make sense, I’m going to start showing you a few maps to clear this up.

A trough is going to continue to dig into the southeastern United States and strengthen as it begins to take on a northwest to southeast orientation. This building trough is eventually going to try to pull Joaquin northward and if it makes the connection, Joaquin could majorly impact somewhere along the East Coast. There is currently a ridge located west of the storm over Florida, so you’re getting that clockwise-flow around that ridge that’s causing Joaquin to currently meander. Once that breaks down and the trough in the Southeast U.S. starts trying to pull this hurricane north, it’ll make that change in direction. If you’re a visual person, the maps below will clear all of this up.

One reason this gets complex is because the models vary on the exact timing on all of this. The European model is much slower (it has Joaquin meandering longer) causing it to entirely miss the trough connection. It tries, but a ridge begins building to its east over the open waters of the Atlantic. This would steer the storm away from the United States.

GFS Joaquin solution

Euro Joaquin solution

The GFS model is much quicker with all of this. It pulls the hurricane up faster, makes the connection with the trough, and a ridge to the hurricane’s northeast helps to steer Joaquin right into the East Coast somewhere along North Carolina/Virginia and has the storm riding up the coast. This would be a very bad scenario, not just because of the very strong winds but the excessive flooding potential.

WPC’s 3 Day Rainfall Forecast:

East Coast flooding

Putting All Of This Together:

The European model is taking Joaquin away from the U.S. while the GFS model has the worst-case scenario. Generally, the European model performs much better than the American models, but right now, I’m actually leaning towards this storm making the connection with the trough and impacting somewhere along the East Coast. However, I will admit that I am uncertain about this. The reason I showed you the two scenarios is because each scenario is very viable and realistic. This shows you why meteorology is so complex, and why timing and the placement of troughs and ridges can be the determining factor between a hurricane slamming the East Coast or not being an issue at all.

So, I’m going to keep a close eye on this. I laid out the meteorology, and while I hate to admit it, there will be some nowcasting involved with this forecast over the next couple of days simply because of these complexities.

If you’re along the East Coast, you need to prepare. It’s much better to be over prepared than not prepared at all. In the meantime, I’ll get all of the details ironed out over the next couple of days.