Big Cool Down On The Horizon

A decent cold front will move through central parts of the country late this week into the weekend. The sub-tropical ridge that has kept temperatures across the Southern Plains and Southeast above average recently will begin to move eastward as a trough moves in from the west. This will send a cold front south on Thursday and the front will continue its southward progression into the weekend. The front should move through Nebraska and into Kansas on Thursday into Friday, and through Oklahoma and northern Texas on Friday into Saturday. Tomorrow, along the cold front, a few severe thunderstorms look possible due to forecasted instability and shear values (see Fig. 1).

Fig. 1: Thunderstorm outlook map for Thursday

The front should stall across northern Texas and western parts of the Mississippi and Tennessee Valleys as it feels the influence of the ridge. This will keep temperatures warm for much of the Southeast outside of Arkansas, northern Louisiana, northwestern Mississippi and western Tennessee (cooler temperatures are in the forecast for other parts of the South/Southeast later in the extended period so keep reading for details on the cooler temperatures). Temperatures behind the cold front will be well below average for much of the Southern Plains and Midwest late this week and weekend (see Fig. 2 and 3).

Fig 2: Friday afternoon temperature anomalies

Fig 3: Saturday afternoon temperature anomalies

It should be noted, deep moisture will move into New Mexico, Texas and Oklahoma from Thursday into Saturday as the trough nears. This moisture will stream into this region from the Gulf of California where a Tropical Depression is located this afternoon. The increase in moisture will lead to increased rainfall, which may lead to flooding in parts of New Mexico, Texas and Oklahoma. Isolated areas in Texas and Oklahoma may see 2-6″ (see Fig. 4). The increase in precipitation and cloud-cover should keep afternoon temperatures below average even before the front moves through on Friday (see Fig. 2 and 3). High temperatures late this week into the weekend should be in the 60s and 70s for Oklahoma and 80s for most of Texas.

Fig. 4: Rainfall forecast through 7 days

Looking ahead to next week, a more amplified trough appears to usher in a reinforcing shot of cooler air. The cooler air will first be felt across the Northern Plains early next week, followed by the Southern Plains by mid-week, then eventually parts of the Southeast by late week into next weekend. Far Southeastern parts of the United States (Florida, eastern Georgia, South Carolina, and eastern North Carolina) may miss out on the coolest fall-like temperatures from this front but temperatures should still decrease. For other parts of the South, this will be the first significant cold front of the fall season. High temperatures will be well below average (see Fig. 5). It is too early to forecast high and lower temperatures with much confidence but right now it appears highs may be in the 60s and 70s with lows in the 40s and 50s behind this front. Locations further north will see temperatures much cooler than this.

Fig. 5: Temperature probabilities days 8 through 14

Hurricane Florence Forecast Update – Impacts Begin Tomorrow

Florence remains to be a powerful category 3 hurricane with maximum sustained winds of 120 mph. Some weakening has occurred today, but there will be one last window tonight and early tomorrow for Florence to have another shot at strengthening a bit before its center begins to reach the southern North Carolina/northern South Carolina coasts.

This will be a very brief article on some of the slight modifications that I made to my forecast.

The first image below shows the official track and cone of uncertainty from the National Hurricane Center. Their latest forecast has Florence making landfall along the southern coast of North Carolina before moving into South Carolina. I plotted their forecast on a county map, so that you can see it a bit better.

hurricane florence track

hurricane florence track county map

The Weather Prediction Center’s latest rainfall forecast indicates that 20+ inches of rain will fall along and just inland from the southern North Carolina/northern South Carolina coasts. Some regions could exceed 40 inches of rain. For those in any region that is forecasted to get around or above 4 to 6 inches of rain, take special note. The flooding situation that evolves will be the big story with Florence.

hurricane florence rainfall forecast

I made no changes to my landfall forecast from last night. It’s within the realm of possibilities that Florence could skirt southwest along the South Carolina coast once interacting with land, but I decided not to account for a possible second landfall that might occur. Getting into very technical details likely won’t change the overall impacts anyway.

hurricane florence landfall forecast

I made some modifications to my impacts map. I extended the pink zone, the region where I believe impacts could be severe, farther northeast along the North Carolina coast. Even though a landfall should occur farther southward, high storm surge will likely be very high well-away from the storm’s center to the right. I made no modifications to the pink zone in South Carolina. I’m not confident enough at this point that Florence won’t attempt to make a turn southwestward along the South Carolina coast. If I gain more confidence that for some reason that won’t occur, I’ll modify that part of the forecast tomorrow.

hurricane florence impacts map

Other than that, I trimmed back some of the red zone, the region where I believe at least some impacts could occur, for parts of Virginia. I made some subtle changes across Georgia, Tennessee, and West Virginia to include additional locations. Generally, the red region is where I believe tropical storm-force winds (or gusts) and/or flooding will occur. Since Florence is quite large and will slow significantly, that accounts for some of why that region is so large.

Please stayed updated on Firsthand Weather for future updates.

Hurricane Florence Likely To Be Catastrophic For Parts of the Carolina Coast

After Florence’s recent eyewall replacement cycle, it has re-strengthened into a 140 mph hurricane. Strengthening is expected to continue, given that vertical wind shear will be weak, sea surface temperatures will be more than sufficiently warm, and little dry air will be present to mix into Florence’s core. In an effort to answer many unanswered questions, I’ve made a couple of maps. Let me briefly explain what they mean.

The first map includes where I believe Florence will be making its (first) landfall. Some southern shifts in track could occur; thus, I’ve included the northern South Carolina coast as a potential landfall location. Given the fairly good consistency amongst the models on landfall location, I decided not to shift the landfall threat farther south. I’ll decide tomorrow if I need to make any additional shifts southward. Locations in and around the circled region is where I am currently anticipating damage to reach catastrophic levels.

Hurricane Florence landfall

The second map includes the regions that could be impacted by Florence, whether that’s from wind, flooding, or coastal storm-surge. Most of the forecast model guidance today made a noteworthy shift westward (and even southwestward) in Florence’s track once it reaches the southern North Carolina and northern South Carolina coasts. Some of the guidance even brings the center back over water and has a second landfall occurring farther southward into South Carolina. Weak steering flow is making this a particular challenging forecast. A high pressure ridge to Florence’s east/northeast and also to its west will result in Florence slowing significantly near the coast. The pink zone is where I’m currently most concerned about; while some parts of the red zone could experience significant impacts as well. At the least, I expect those in the red zone to experience some impacts from wind and rain. If the southward trend continues, I may end up chopping parts of northern Virginia out of the red zone, but in this update, I mainly included them due to potential flooding. I’m sure modifications will have to be made to the forecast, since we’re now getting down to the county-level.

Hurricane Florence impact zones

Please continue to follow Firsthand Weather on Facebook and this site for future updates.

“Joyce” to impact Texas?

Firsthand Weather is keeping a very close eye on the convection located over the southeastern Gulf of Mexico and northwestern Caribbean (see Fig. 1). This area of convection will persist over the next 48 hours and should begin to organize by 48-72 hours into Tropical Depression/Storm Joyce. Right now, the upper-level winds are not conducive for organization but these winds will become more favorable by late week. The majority of the European ensemble members are showing development with a northwest movement into southern Texas by Friday (see Fig. 2) and the GFS and Canadian show a decent area of pressure falls (hinting at a Tropical Depression/Storm) in the same vicinity. This is why the National Hurricane Center (NHC) has given this area a 50% chance of development over the next two days and a 70% chance of development by day five (see Fig. 2).

Fig. 1: Convection that may develop into Joyce later this week

Fig. 2: European ensembles

Fig. 3: Area being monitored by the NHC
By late week, what could be Tropical Storm Joyce should be in the western Gulf. This will lead to copious amounts of moisture moving into south and coastal parts of Texas. Widespread 4-8″ of rainfall are possible with the possibility of amounts exceeding 10″ in areas (see Fig. 4). This part of Texas has received above average precipitation as of late, thus, the grounds are saturated; leading to an enhanced flash flood threat for the region from Thursday through the upcoming weekend.

Fig. 4: 7-day rainfall forecast
While a general WNW to NW motion is what is depicted by numerical guidance, much uncertainty does exist with the track of this system. Generally, the consensus of guidance has a landfall between Corpus Christi and South Padre Island. This could deviate further south or further north depending on the strength of the system. A stronger Tropical Storm/Hurricane would likely force a more WNW motion due to the 500mb ridge possibly intensifying to the north whereas a weaker Tropical Depression/Tropical Storm would likely track more to the NW.

Regardless of development into Tropical Storm Joyce, this system will lead to an influx of moisture into parts of southern Texas, which will increase the flood threat. Other hazards associated with this area of disturbed weather for Texas are: rough seas, rip currents and gusty winds. Keep checking back for updates because the waters are warm in this area so if organization occurs faster than expected, it is possible this system could ramp up quickly.

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.

Hurricane Florence Could Directly Hit The East Coast But Uncertainty Still Remains

Good Saturday evening, everyone! So, let’s jump right into talking about Florence. The storm remains quite a distance to the southeast of Bermuda, and unlike what I was expecting a few days ago, Florence should track well to Bermuda’s south before making its approach towards the East Coast. Given Florence’s current location and previous track, it’s remarkable that this system isn’t going to curve out to sea a safe distance away from the East Coast, and although I included the East Coast impact scenario in my previous article, I previous leaned towards an out-to-sea scenario. While it physically made sense that Florence could approach the coast, it’s become apparent that I relied too strongly on how other tropical systems behaved in the same vicinity as Florence. Although it’s never a bad idea to take this approach, it must be understood that every storm and situation is different. Last winter when parts of Georgia received over a foot of snow, Firsthand Weather produced a highly-accurate forecast by going against climatology. Sometimes, that’s what has to be done, and it should have been done in this case, too!

Florence is currently only a tropical storm with maximum sustained winds of 70 mph as of Saturday evening. Remarkably, Florence was previously able to intensify into a major hurricane despite being in an environment of moderate to strong vertical wind shear, which gives me yet another reason to point out why we have a lot to learn about tropical cyclone rapid intensity changes. Eventually though, wind shear and drier air began to take its toll on the storm, but don’t let that fool you! Florence will once again strengthen into a major hurricane. The first graphic below shows the National Hurricane Center’s current projected track for Florence, which I overlaid with current sea surface temperatures. Florence is currently located in a region where sea surface temperatures (SSTs) are around 27.5°C/81.5°F but is moving into a region where those waters are much warmer (around 29.5°C/85.1°F). With the combination of warming SSTs and lighter wind shear, the environmental conditions are going to become increasingly conducive from rapid intensification. This is why NHC now forecasts Florence becoming a 145 mph hurricane in 96 hours!

Hurricane Florence track and warm waters

So, there continues to remain a bit of uncertainty about exact track, which I know is the last thing most of you want to hear since many of you are trying to make preparations. Let me walk you through the forecast, and then I’ll share my thoughts on how everyone should be making preparations. The NHC has Florence approaching the Carolina coast, shown on the first image below. Now remember, the cone is simply a projection of where the center of the storm could go. That has nothing to do with impacts, which always occur outside of the cone. Anyway, the NHC forecast generally agrees with what most of the operational guidance has been indicating, along with the ensemble means. But take a look at the spread in the European ensembles (courtesy of Ben Noll’s website). Each red line represents a member of the group of ensembles, and those members have Florence making landfall anywhere from northern Florida to the Mid-Atlantic. Some even have Florence skirting along the coast/curving out to sea, something that cannot be entirely ruled out.

NHC Hurricane Florence Track

Two main factors are at play here. First, we must continue to monitor how far to the south Florence remains this weekend. That alone could determine how far to the south Florence will be as it approaches the coast. But here’s another key factor. . .the strength of the developing ridge that will build to Florence’s northeast and then attempt to strengthen to Florence’s north. This is the feature that is currently expected to steer Florence towards the coast. IF the ridge were to be weaker than currently projected and if Florence could gain a decent amount of latitude this weekend, that would put Florence very close to the East Coast, but it’d possibly curve along the coast instead of making landfall. Given these two uncertain factors, residents from the northern Florida coast to North Carolina need to go ahead and begin making preparations, keeping in mind that all of those locations won’t be getting the brunt of the storm. On the map below, I only circled regions near the coast that could be heavily impacted by Florence, but impacts will extend beyond that boundary farther inland, if a landfall does occur.

Hurricane Florence impact zone

Although I understand that my outlined boundary covers a lot of real estate, I encourage anyone in those areas to begin making some preliminary preparations over the rest of this weekend. On Monday or Tuesday evening, I will produce a follow-up post with an updated map that will be a lot more narrowed down at that point. Please continue to Firsthand Weather on Facebook for future announcements on when the latest updates and articles will be published.

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.

Gordon Intensifies, Voluntary Evacuations Issued

2:00PM Eastern Update (Monday):

Tropical Storm Gordon is a spinning off of the southwest coast of Florida. Gordon has intensified with maximum sustained winds of 50 mph and continues to have an improved structure on satellite and radar (see Fig. 1). The improved structure as favorable environmental conditions suggest further strengthening is likely and Gordon should become a hurricane over the next 24-36 hours before landfall across the central Gulf Coast.

Fig. 1: Latest IR imagery

A Hurricane Watch is in effect from the mouth of the Pearl River to the Alabama/Florida border (see Fig. 2). A Tropical Storm Warning is in place in Florida from Golden Beach to Bonita Beach, and for the Florida Keys from Craig Key to Ocean Reef, including Florida Bay as well as from the Okaloosa/Walton County line in Florida westward to east of Morgan City, Louisiana, including Lake Pontchartrain and Lake Maurepas (see Fig.2). Areas along the central and eastern Gulf Coast (including areas inland) need to prepare for heavy rainfall, gusty winds, isolated tornadoes, and rip currents and coastal flooding for immediate coastal areas within the next 24-48 hours. Excessive rainfall totals will be experienced well inland (see Fig. 3). It is possible these totals need to be increased further north into parts of Alabama, Mississippi, and Arkansas–this is heavily dependent upon the track of Gordon.

Fig. 2: Latest watches/warnings

Fig. 3: Precipitation forecast through 7 days

Gordon should make landfall Tuesday night along or near the Mississippi coast (see Fig. 4). Please note, anyone within the cone, and even locations near the cone, need to keep a close eye on the forecast over the next 24 hours. It is possible the forecasted track may change. This is a fluid situation and tropical storm conditions will begin to be experienced along northern parts of the Gulf coast by Tuesday. A voluntary evacuation order has been issued for Grand Isle, Louisiana and schools have also closed for September 4th in Grand Isle. People are urged to stay up to date along the coast in case local officials issue evacuation orders.

Fig. 4: NHC forecast cone