Tropical Update: Harvey and Hurricane Safety

Hurricane Harvey, now 115 miles southeast of Corpus Christi Texas, has seen the maximum sustained winds increase to 110 this morning, just shy of major hurricane status. The minimum central pressure has dropped 947 Millibars. Harvey is expected to become a major hurricane today with winds increasing further to 120 mph. As of this 11 AM EDT, the following watches and warnings are in effect.

A Hurricane Warning is in effect from Port Mansfield to Sargent Texas. Hurricane conditions will be occurring in these areas within the next 12-24 hours.

A Tropical Storm Warning is in effect from south of Port Mansfield to the Mouth of the Rio Grande River and from North of Sargent to High Island Texas

A Tropical Storm Watch is in effect for South of the mouth of the Rio Grande to Boca de Catan Mexico

A Storm Surge Warning is in effect from Port Mansfield to High Island Texas. A Storm Surge Warning means there is a danger of life-threatening inundation from rising water moving inland from the coastline in the indicated locations. This is a life-threatening situation. Persons located within these areas should take all necessary actions to protect life and property from rising water and the potential for other dangerous conditions. Promptly follow evacuation and other instructions from local officials.

A Storm Surge Watch is in effect from south of Port Mansfield to the Mouth of the Rio Grande. A Storm Surge watch means there is a possibility of life-threatening inundation from rising water moving inland. Persons located within these areas should take all necessary actions to protect life and property and be on the look out for rising seas.

Forecast Information

Harvey

Hurricane Harvey continues to increase in strength this morning and is now approaching major hurricane status. Harvey is expected to be a category 3 storm when he moves ashore in Texas. Sustained winds are expected to be between 120 and 130 miles per hour with higher gusts. Harvey will be bringing life-threatening storm surge, rainfall, and wind hazards to portions of the Texas coast. Preparations to protect life and property should be completed this morning, as tropical storm force winds will first arrive in the hurricane and storm surge warning areas later today.

Life-threatening storm surge flooding could reach heights of 6 to 12 feet above ground level at the coast between the north entrance of the Padre Island National Seashore and Sargent. Devastating and life-threatening flooding is expected across the middle and upper Texas coast from heavy rainfall of 15 to 25 inches, with isolated amounts as high as 35 inches, from today through next
Wednesday.

Harvey will hug the coast after he moves inland, which could help prevent the quick weakening associated with land falling hurricanes. While Harvey will still weaken, it may be a slower process and he could maintain Tropical Storm strength longer than usual. Harvey is forecast to impact this area for several days.

Hurricane Harvey Hazards

Storm Surge and Storm Tide

Storm Surge and large waves are the greatest threats to life and property along the coast. A storm surge is an abnormal rise of water generated by a storm’s winds. Many will remember the surge from Hurrican Ike is 2008. Storm Surge with Harvey is expected to be as high as 12 feet in some locations (was 20 feet in Ike). Please check your local media sources for the exact surge totals expected for your area. Surge related flooding will be dependent on the exact timing and the tide and can vary greatly over short distances. Large waves will also be a factor at the coast. Based on the tide charts, Harvey should hit as tides are moving out and close to low tide, but onshore winds are possible during several tidal cycles.

Tornadoes

Hurricanes frequently produce tornadoes, usually in the embedded thunderstorms in the rain bands now beginning to hit the Texas coast line. They can also be associated with the eye wall. Tornadoes produced by these systems are usually weak and short lived, but they can be a threat to where they hit. A Tornado watch is expected to be posted for coastal areas of Texas and Louisiana later today.

Winds

It goes without saying that winds are a major issue with Hurricanes. Sustained winds with Harvey are expected to reach up to 120 mph with gusts reaching as high as 150 mph with some locally higher gusts. Harvey is forecast to be a major Hurricane at landfall.

Rainfall

Forecasts for Harvey have indicated significant rainfall is possible, with some models showing over 30 inches of rain. This will be a very long duration event and flooding and flash flooding will bea major issue for many areas.

Hurricane Safety

Evacuations

Many areas in Texas have had evacuation orders given, for those who are evacuating, you will need to determine a safe evacuation route inland. 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. The good news is that a quick check of traffic in this region doesn’t show any, so many heeded these orders in advance.

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. Snacks and stuff to drink will also be good for longer evacuations, especially with children. 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, gas supplies may also be strained along your route. 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 is brining a large area of rain to Texas and the location you were heading for may end 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. 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. When it comes to repairing your rain gutters, it’s as easy as checking out sites such as https://www.aluminiumwarehouse.co.uk/, finding the right materials and replacing your damaged/old gutters. This will help protect your property, which is what you need to consider, especially after weather conditions like thunderstorms and heavy rain. This can also help keep them lighter and not fall under the weight of all the rain. 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 may also want to get in touch with a home improvement service similar to Mastershield Atl that may be able to provide support for homeowners who are looking for a way to protect their roof from water damage. While it is certainly too late to hire a contractor to do this for Harvey, other storms will come along and this can be done for future storms. 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. 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.

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

Harvey Likely To Drop Excessive Rainfall Along Texas/Louisiana Coasts

Quick note: This is a forecast that I wrote specifically for a tropical meteorology class that I’m taking, which is why the format is a bit different than what you’re used to seeing from me. However, I figured all of you would find this information beneficial.

Discussion on Harvey (August 24, 8 am CT update):

As expected, Harvey re-strengthened back into a tropical storm last night and now has sustained winds of 50 knots. Harvey has picked up some forward speed and is currently moving north- northwest at 9 knots. Convection is now much better focused around Harvey’s center, and he does not have the elongated look that he did just last evening. At this time, no modifications/updates need to be made to last night’s forecast (below).

Hurricane warnings have now been issued for parts of the Texas coastline. Excessive rainfall is still expected, and at this point, it is not unreasonable to say that parts of Texas could exceed 20 inches of rainfall over the next 5 to 7 days.

Harvey Projected Path

Figure 1: Tropical Storm Harvey’s latest projected path from the National Hurricane Center

Discussion on Harvey (August 23, 7:00 pm CT update):

As of 7:00 pm CT, Tropical Depression Harvey is currently to the west of the Yucatan Peninsula and is moving very slowly to the northwest at 2 knots. After weakening and losing its closed circulation earlier in the week, Harvey finally made its transition back into a depression and will likely strength into a tropical storm by tonight or tomorrow morning. At this point, hurricane status may eventually be reached before landfall.

An upper-level low has been positioned just to the south of the Texas/Louisiana border over the Gulf of Mexico, which has resulted in an elongated region of convection firing from Harvey’s center of circulation extending northward away from this center in an area of heightened upper- level divergence. Harvey’s circulation has been quite elongated thus far, but convection should eventually become more confined to Harvey’s center as the upper-level low dissipates.

With time, vertical wind shear should decrease ahead of Harvey, as the upper-level low dissipates. There is currently moderate to strong vertical wind shear that extends south of the Louisiana coast to the northeast Gulf of Mexico. The southern extent of this stronger shear has likely played a role in Harvey’s disorganized and asymmetrical look so far this week, but over time, this should no longer be a significant hindrance to Harvey’s intensification, especially as this tropical system moves northwest.

atlantic vertical wind shear

Figure 2: Locations of vertical wind shear across the Gulf of Mexico and western/central Atlantic from CIMSS

atlantic upper-level winds

Figure 3: Upper-levels wind across the Gulf of Mexico and western/central Atlantic from CIMSS

Sea surface temperatures are anomalously warm over much of the western Gulf with temperatures running around 30 to 31°C on average. Even more noteworthy, Harvey will be moving over a region of higher ocean heat content, so while some upwelling could occur due to Harvey’s slow forward motion, it appears that this system has plenty of warm, Gulf of Mexico water to enhance strengthening. In addition to warmer sea surface temperatures and a low-shear environment, there will be very little dry air to hinder further development.

gulf of mexico ocean heat content

Figure 4: Gulf of Mexico and western Caribbean ocean heat content map from CIMSS

GOES-16 Harvey water vapor

Figure 5: GOES-16 water vapor image from early morning, August 24, 2017

Aside from the fact that Harvey could quickly intensify as he moves towards the Texas coast, one major concern at the moment is the significant flooding situation that could unfold across Texas and Louisiana. A region of high pressure is expected to build over the eastern Gulf of Mexico by this weekend, while ridging is expected to amplify over the western United States around the same time. The mean flow will generally be from the north on the east side of the western ridge and from the south on the west side of the eastern Gulf high pressure system, putting Harvey is a region of weak steering flow. Unless one of these high pressure regions becomes more dominant than the other, Harvey will likely meander along or just inland over Texas for quite some time. Broad troughing over the eastern U.S. could eventually pull Harvey northeastward next week, but at this point, that remains uncertain. Due to the complexity of this pattern, model guidance has had a difficult time determining where Harvey will go once he moves closer to the Texas coast. Given the moisture-rich environment that will be present along the Texas and Louisiana coasts and the frontal boundary that will remain stalled across that region, rainfall totals over the next 5 to 7 days could reach 10 to 20+ inches across those locations. Reaching such totals will be highly dependent on the overall track of Harvey, which will be dependent on the strength and exact placement of the two high pressure features.

harvey rainfall totals

Figure 6: 7-day rainfall forecast from the WPC

Discussion on the rest of the Atlantic (August 23, 7:00 pm CT update):

Aside from Harvey, the rest of the Atlantic is relatively quiet. There is a trough of low pressure that is currently located near the Florida peninsula, which is bringing unsettled conditions south of a frontal boundary that will continue to makes its way southward.
In addition to sea surface temperatures being anomalously warm across the Gulf of Mexico, temperatures are also warm across the main development region. This will be extra fuel for any African easterly wave that moves across that region. It is worth noting that there is quite a bit of dust that is now moving over the eastern Atlantic from Africa, which for the time being, will likely hinder the development of any wave in that region.

global sea surface temperature anomalies

Figure 7: Weekly global sea surface temperature anomalies from NOAA

saharan air layer map

Figure 8: Saharan air layer map from NOAA

Discussion on the eastern and central Pacific (August 23, 7:00 pm CT update):

For now, the tropics in the eastern Pacific are quiet. Kenneth recently dissipated after moving northward into a region of lower sea surface temperatures. While sea surface temperatures are anomalously cool over the central and eastern equatorial Pacific, sea surface temperatures are above average north of that region, including near Hawaii. As the hurricane season continues, that region will bear watching.

central pacific sea surface temperature anomalies

Figure 9: Sea surface temperature anomalies across the central Pacific from Tropical Tidbits

Tropical Storm Harvey Rapidly Strengthening

Harvey intensified overnight and is now a Tropical Storm with maximum sustained winds of 60 mph. Harvey is moving towards the Texas coast, to the NNW, at 10 mph. The latest analyses shows Harvey is in a favorable area for continued strengthening, and the latest microwave imagery shows Harvey has a closed eye wall. This means Hurricane status will likely be met later today as the winds ‘catch up’ with the closed eye wall and decrease in pressure, and Harvey will likely make landfall as a Hurricane near Corpus Christi late Friday night/early Saturday morning.

Microwave Satellite

IR Imagery

NHC Cone

Spaghetti Plot

Hurricane Warnings are in effect for Port Mansfield to Matagorda, Texas; Tropical Storm Warnings are now in effect north of Matagorda to High Island, Texas and south of Port Mansfield, Texas to the mouth of the Rio Grande. Once Harvey moves inland in Texas, it will likely meander in southern Texas for a day or two. This will cause extensive, deadly flooding for much of southern Texas and southern parts of central Texas. Widespread 10-25″ of rain are possible with isolated amounts in excessive of 30″. San Antonio, Austin, and Houston are included in this flood threat.

GFS Rainfall Totals

More details on the impacts across other Gulf States later today.

Harvey: Dangerous Storm For Entire Gulf

The National Hurricane Center (NHC) has reclassified the low in the southwestern Gulf of Mexico as Tropical Depression Harvey. Reconnaissance data indicates that Harvey has maximum sustained winds of 35 mph and is moving towards the NW at 9 mph. This motion is expected to continue through the week as Harvey develops into a hurricane near the Texas coast.

NHC Forecast Cone

By Friday, it looks likely that Harvey will reside close to the mid-Texas coast. With low shear and warm sea-surface temperatures, it is likely that Harvey will be a hurricane at this time. This would create strong winds and potentially a damaging storm surge for parts of the Texas/Louisiana coast (depending on the strength and position of Harvey). Very heavy rainfall is another major threat with Harvey, and this rain threat is not only for coastal areas.

Since Harvey will likely slow down and meander around the coast late into the week/early weekend, this will draw in copious amounts of moisture into southern Texas and Louisiana–leading to an increased flooding threat. This meandering scenario looks likely due to the steering pattern associated with the TUTT low over the northwestern Gulf. There is uncertainty as to how long Harvey will meander near the Texas coast; the synoptic evolution is important in determining the eventual eastward or northeastward motion of Harvey–this is highly dependent on where Harvey resides on Friday. If Harvey is closer towards the southern Texas coast, more of an eastward motion may resume by late in the weekend. But, if Harvey is further towards the mid-to-upper Texas coast, then phasing will likely occur which would shift Harvey east-northeastward/northeastward shifting the heavy rainfall threat further north and eastward along the Gulf states through early next week.

Regardless, it appears widespread 10-20″ of rainfall are across southern Texas with several inches possible further inland towards southern parts of central Texas; depending on how long Harvey meanders along the coast, a few areas could see well in excess of 20″. Louisiana, Mississippi, and Alabama will likely receive heavy rainfall by late in the weekend into early next wee. Southern Louisiana may pick up 10-15″ of rainfall wile the rest of Louisiana and central/southern Mississippi may see 3-7″. Isolated much higher amounts are possible across the Gulf states.

Spaghetti Plot

WPC Precipitation Forecast Through 7 Days

GFS Rainfall Forecast

A Storm Surge Watch has been issued for the coast of Texas from Port Mansfield to High Island, aHurricane Watch has been issued for the coast of Texas from north of Port Mansfield to San Luis Pass, and a Tropical Storm Watch has been issued for the coast of Texas from the Mouth of the Rio Grande to Port Mansfield and from north of San Luis Pass to High Island. We will have updates as needed.

Latest Spaghetti Plot: Entire Gulf Needs To Remain Alert

Firsthand Weather is keeping a close eye on the Gulf of Mexico this week as the remnants of Tropical Storm Harvey move into the southwestern Gulf. Impacts to the United States are looking more likely–especially for Texas then there’s the potential the remnants may impact additional Gulf States (Louisiana, southern Arkansas, Mississippi, Alabama, and Tennessee), so I wanted to provide a brief post on the latest spaghetti plot with you all.

The National Hurricane Center (NHC) is monitoring the remnants of Harvey (currently crossing the Yucatan Peninsula), and is giving the low a 70% of tropical cyclone development over the next 48 hours and an 90% chance of tropical cyclone development over the next five days. The current analyses show decent spherical vorticity, light environmental shear ahead of the system in the Bay of Campeche, and above average sea-surface temperatures. This should allow the remnants to develop into a tropical cyclone by Wednesday afternoon. It is possible the NHC may label this as a Potential Tropical Cyclone by the afternoon hours today, which would allow local National Weather Service offices to begin issuing weather products (watches) on this system.

Numerical guidance has begun trending further northward over the past few runs. This has shifted the potential track from northern Mexico, more towards the Texas coast. This means the entire Texas coast needs to keep a close eye on future forecasts as confidence continues to increase.

On to the spaghetti:

So what exactly are spaghetti plots? Spaghetti plots are what meteorologists refer to when multiple numerical weather models are shown together. This creates a spaghetti like appearance because the individual model tracks are all plotted on the same image. These plots are important because they can give some insight into where a tropical system may track.

Here is the latest spaghetti plot for the remnants of Tropical Storm Harvey that’s heading towards the Gulf of Mexico. The 12Z guidance is clustering a landfall along the mid-Texas coast. This is a drastic shift northeastward over the past 24 hours. Guidance will continue to need to be assessed to determine if future shifts (northward or southward) are possible.

If you live along the Texas coast, you need to prepare now for potential tropical cyclone impacts. This is a precautionary measure in case impacts are felt late in the week. The other Gulf States should keep a close eye on this system, too, because it is possible it may phase and get pulled into Louisiana and Mississippi.

See yesterday’s article about the remnants of Harvey!

Texas and Southeast Tropical Cyclone Threats?

Firsthand Weather is keeping a close eye on the tropics this week. There are two systems that may impact two separate regions across the United States this week.

Northern Mexico and Texas: Remnants of Harvey (Caribbean)

The first area we are monitoring is the Caribbean, which is where the remnants of Tropical Storm Harvey reside. The National Hurricane Center (NHC) is monitoring the remnants of Harvey, and currently is giving the low a 50% of tropical cyclone development over the next 48 hours and an 80% chance of tropical cyclone development over the next five days. The current analyses show decent spherical vorticity and light environmental shear. The main hindrance from immediate development is the speed at which the low is moving and the close proximity to land. There is likely not enough time, before the system crosses land, to undergo intensification into tropical cyclone status. This intensification may occur later in the week (more details below).

Area Being Monitored (NHC)

850mb Current Vorticity (University of Wisconsin)

Current Environmental Wind Shear (University of Wisconsin)

The remnants will move across the Yucatan Peninsula on Tuesday and cross into the Bay of Campeche (southwestern Gulf of Mexico) by Wednesday morning. While the remnants will likely remain below Tropical Depression/Tropical Storm criteria before moving across the Yucatan, heavy rainfall, rough seas, and gusty winds are possible across this area.

As the remnants move into the Bay of Campeche, environmental conditions appear to become favorable for development into a tropical cyclone. Global numerical guidance is indicating a steering pattern that may be favorable for a northwestern movement. The latest GFS and European have a general landfall between Tampico and Brownsville around Friday. This position would wrap in rich moisture into southern Texas and generate rough seas along the coast. With a cold front likely draped somewhere in the vicinity (southern Texas/central Texas), a flooding scenario could set up. The future intensity of the remnants and how much of a northerly component these remnants will take remain uncertain, but close monitoring is required.

GFS 850mb Vorticity (Friday Morning)

European 850mb Vorticity (Friday Evening)

Spaghetti Plot

Southeast (Florida): Invest 92 L (Atlantic)

The second area we are monitoring is the Atlantic (near the Bahamas), which is where a broad area of low pressure resides. The NHC is monitoring the low and currently is giving the low a 10% of tropical cyclone development over the next 48 hours and an 40% chance of tropical cyclone development over the next five days. The current analyses show a non-symmetrical/elongated vorticity, but environmental wind shear is light. Low-level convergence is also weak currently.

Area Being Monitored (NHC)

850mb Current Vorticity (University of Wisconsin)

Current Environmental Wind Shear (University of Wisconsin)

There is less confidence with this broad area of low pressure, which is visually displayed in the latest spaghetti plots. The timing and movement are big questions. The GFS shows this area of low pressure developing into a weak tropical cyclone (Tropical Depression). The European is not as bullish with tropical development, but shows a low developing with an upper-level trough off of the East Coast. Both scenarios indicate deep moisture being pulled into Florida, which will aid in heavy rainfall.

GFS 850mb Vorticity (Friday Evening)

European 850mb Vorticity (Friday Evening)

Spaghetti Plot

Firsthand Weather will keep a close eye on these two systems over the next few days. As confidence increases in the movement and intensity forecasts, we will provide updates.

Cooldown Coming To Southeast

A change in the upper-level pattern will lead to a noticeable cooldown for the Southeast by mid-week, which will continue into the upcoming weekend. This pattern change has been consistently advertised on the global models, thus, confidence is high in this scenario.

The upper-level changes will send a cold front through the Southeast by mid-week. Behind the front, drier and cooler air will advect into the Southeast; temperatures will be 5-10 degrees Fahrenheit below average from Thursday through the weekend. Highs will drop into the low to mid 80s, with lows dipping into the 60s–a few 50s are possible across the Tennessee Valley by Friday morning. Along with cooler temperatures, humidity levels will decrease, which will make for very comfortable afternoons. The only exception is for areas closest to the coast and Florida. The cool front’s momentum will slow and will struggle to provide much relief for these areas.


GEFS 2m Temperature Anomaly August 24th-29th

GFS Friday Morning Lows

Enjoy the break from the heat!

Tropical Safety: When storms are away, in the ocean we play

Tropical systems can be a source of fun and danger at the beach.  I know from personal experience that when I got to the beach, I don’t want to see calm seas.   I like waves.   The bigger the waves are, the more fun I have playing in them.

There was always common sense involved though.   I never went out there alone.  I wouldn’t go out in high surf at night.  When lifeguards were around, I always tried to pick a spot near them.  While high surf can be fun, knowing the inherent dangers involved is key to enjoying your experience.

Unfortunately, when Hurricane Gert moved up the east coast this month, not everyone was able to survive their experience.  A rip current off Nantucket took several swimmers out to sea and despite a quick and heroic response by local lifeguards, 1 swimmer tragically lost their life to the heavy surf.  This rip current, and the 12 foot waves that accompanied it, occurred despite the Hurricane being more than 400 miles away.  High surf advisories were in effect at the time but several beaches didn’t close until later in the day.

While Tropical Storm Harvey does not pose a risk at this time to the United States, there are several storms in the Atlantic that bear watching.  These storms could produce the same style of swells that the east coast saw with Gert.   Safety in landfalling Tropical Cyclones is a very obvious need, but the less obvious safety risks associated with tropical systems that aren’t approaching your area may be less obvious.  Listed below are some things to look for in heavy surf conditions and some hazards to be wary of when at the beach during storms that aren’t right on your doorstep, but don’t think they can only occur when tropical systems are at sea, while they are more common during this time period, all of these hazards can occur at anytime.

Tropical Hazards in the Ocean

Sneaker Waves

Sneaker waves are generally found along the west coast of the United States.  Somewhat similar to the phenomenon of Rogue waves,  Sneaker waves are unpredictable large waves which can appear without warning and travel much farther up the beach than normal, even when the ocean seems calm.  Some sneaker waves have  been seen to move up to 150 feet higher up the beach than the preceding waves.  That puts an adult beach goer in water potentially up to their waste in water when they were on dry land moments before.  This would be over the heads of smaller children.

A wave of this force would also batter the person impacted by it causing them to fall, and many swimmers have reported being pulled out into the ocean as the waves recedes.  Objects in the ocean or on the beach can also be dangerous in these situations.  Imagine someones beach chair being picked up in a wave and tossed into you as you walk along the beach.

For swimmers in the water, this wave could temporarily put the water level way over your head and will create a significant undertow.  Even a swimmer who was only 50 feet from shore could now be up to 200 feet from the beach.  The advice for this type of wave is the same as a rip current.  Swim parallel to the beach.  The Sneaker wave will not take up the entire area of the beach.  Pay attention to your surroundings and find the closest edge of the wave and swim out of it.

Rip Currents

This rip current, created by the breach in the sand bar, is rather obvious.  You can see the current pouring through the break and the effects it has on the ocean side of the sandbar.    Not all currents make things this simple though.   If this sandbar had been underwater, the rip current would still exist,you just wouldn’t be able to see it as well.  For example,

tropical

As you can see with this current, there is no obvious above the water break to be seen.  But the green dye put in the water shows a very obvious current.  Based on this photo, the things you want to look for become clearer.  On the beach itself, you see much less of a break in the waves at the location of the current than you do surrounding it, despite the wave going higher up the beach.  You can see the same process with the next breaking wave further out.  This is because the rip current undercuts and pushes back against the wave.  Note  that the water appears much calmer and less frothy in the region of the current.  This is the biggest hazard of  rip currents, as it appears that the water there is calmest, and most people associate calm waters with safety.   This falls under the caveat of being too good to be true.  If the rest of the beach is getting hit with waves, there is usually a reason that one specific part isn’t.

As mentioned before, the way to safety from a rip current is to swim parallel to the beach.   The current will be very difficult for even strong swimmers to win against, but the current is likely not that wide, as shown in this photo.  Simply swimming 15 feet to either side of that current should be sufficient to put you outside and allow you to swim back to safety.   Some currents will certainly be wider than this, but it will be far easier to get out of the current than it will to fight it.

Plunging and Surging waves

Plunging waves are the most dangerous type of breaking waves. With a lot of force, they can easily slam your body into the ocean floor. Many spinal and head injuries are caused this way.  You are likely most familiar with these types of waves from surfing where they form a tube.   The wave is created by sudden changes in depth at the beach which causes the crest to become more vertical.  The force of the wave “plunging” down on to you is the primary danger for this type of wave.

Surging waves can also be dangerous as they can easily knock both children and adults over as they rush up and back down the beach.   The danger behind these waves is the lack of a noticeable breaker.  The base of the wave moves much faster than the top of the wave, which makes the wave appear more shallow and less dangerous.  However, the speed with which the wave moves is similar to a river that floods over a road in heavy rain.   It only takes a little rushing water to create a strong force.

Shallow water

The best way to avoid  this hazard is to know your beach.   During the years I spent living on Nantasket Beach in Hull, Massachusetts, I got to know the beach by my house very well.   I knew the location of the sandbars and knew not to dive headfirst into them when they were underwater.   Not everyone was so lucky, and while I never saw anyone get seriously hurt, many a child came back crying cause water than had been over their head suddenly became water up to their ankles rife with rocks.

Tropical swells can change all that.   When the high tide at your regular beach is much higher than usual, the locations of all the hazards hasn’t changed, but the height of the water and the distance of those hazards from the edge of the water has.

If you know the beach well, you can avoid these situations, but if you’re ever at a new beach, or just aren’t sure of where the hazards are at your regular beach, always go in feet first to avoid diving headlong into the bottom.

 

Robert Millette

Cold And Wet Winter Ahead According To Farmers’ Almanac

Enjoy cold and wet weather during the winter? Well, you’re in luck according to the 2018 Farmers’ Almanac, which is predicting a cold and wet winter for much of the continental United States (outside of the West Coast). This is based on a 200-year-old formula used by the Almanac.

According to the Almanac, the Northeast should prepare for cold and snow. Cold and wet conditions will extend further south than the Northeast, too, which may place much of the South in a favorable region for above average wintry precipitation. The Northern Plains can expect cold and snow during the winter, but this region will experience more moderate (near average) temperatures compared to average. The Pacific Northwest will be drier than normal, while the Southwest will see precipitation near average with mild temperatures.

2018 Winter Outlook (Farmers’ Almanac)

Here’s a regional breakdown based on the Almanac:

Southeast:
Temperatures: Below average
Precipitation: Above average

Northeast:
Temperatures: Average
Precipitation: Above average

South-central:
Temperatures: Average
Precipitation: Above average

North-central:
Temperatures: Average
Precipitation: Average

Southwest:
Temperatures: Average to above average
Precipitation: Average

Northwest:
Temperatures: Average
Precipitation: Below average

This is not Firsthand Weather’s 2018 winter outlook, and this does not necessarily represent our views on the upcoming winter season. Firsthand Weather will have a winter outlook out in a few weeks, so keep checking back for details!

Modelcasting versus Forecasting: Why you can’t just use models

Modelcasting has become a big issue in the meteorological world.   Cell phone apps, websites, and even some forecasters simply look at what each individual run of the model shows them and makes that their forecast.  This has led to large changes in some forecasts and led many of you to ask us why the forecast in your local area has gone from rain, to snow, back to rain and then back to snow 22 times in the past 5 days only for the sun to be shining the day of.

The truth is, just as our knowledge of what the weather will do is imperfect, a computer’s knowledge of what the weather will do is just as imperfect.  A human forecaster can use logic to look at a map and realize that something doesn’t make sense.   A computer has rigid equations and programs and follows them to the letter.  It doesn’t matter to the computer if its showing the worst storm ever known to man, if that’s what the programs and equations say goes there, then the computer puts it there.

As trained forecasters, meteorologists are supposed to know better.  We know the model has biases, that the model has errors.  We are well aware that the model is just downright bad at forecasting certain storm evolutions.  This brings me to newly formed Tropical Depression 8, probably better known to many of you as Investigation area 99L.  A little while back in the comment section on an article about then Tropical Storm Franklin, I was asked about TD8 and how the Euro model was showing a stronger system than other models.   I explained then that the GFS was very weak in forecasting the type of system that 99L was and continues to be, with even the 06Z run this morning continuing to show barely any development of TD8 as we’ll see down below.

Reality against the Machine

The image above is the model forecast for early this morning.   The current NHC data shows that TD 8 has a minimum central pressure of 1011 mb while this model data shows a minimum pressure of 1014 mb.  As you can see from the image, it also doesn’t show much convection.

This is where a meteorologist needs to know their models and how those models do and don’t work.  We here at Firsthand have been looking at this system for Tropical development for days and first mentioned that the system might develop in this area in an article back on August 8th.  We did this despite models like the GFS not showing any development because we know of the models weakness and added value to the model based on our own meteorological knowledge.  This added value by the meteorologist is essential in any forecast.  We head to the image below for another example.

modelcasting

This image, which is the model forecast for Monday afternoon, shows no major closed circulation.  Based on the previous image, this image would even indicate that TD 8 is weakening.  However, the forecast from the National Hurricane Center doesn’t call for weakening.  The forecast expects that TD 8 will have been a Tropical Storm with winds between 50 and 60 mph.  Do you see that Tropical Storm on this image?   I certainly don’t.  Modelcasting this storm would be a disaster if you happened to be on a cruise ship in that area.

Finally,  this image shows what’s supposed to be a tropical system on Tuesday the 14th.  The forecast during this time period calls for a strengthening Tropical Storm with the NHC forecast heading up to 65 mph and nearing hurricane strength.   That type of forecast simply isn’t here on this model and it wouldn’t be on any app that uses this model for it’s forecast.

This same logic seen here with this forecast for TD 8 can be applied to many other scenarios.  Whether its the development of a winter storm, a major outbreak of severe weather, or even something as simple as the morning temperature, The data that goes into and comes out of computer models allows us a much better idea of what the weather is going to do, but that data and the programming that goes into creating those models is only as good as our understanding of that data and programming.

Modelcasting with a computer can solve a lot more equations, but if the equation itself isn’t perfect then the answer to it isn’t going to be perfect either.   The difference is that meteorologists who use the data as a tool, instead of just modelcasting and outright using the data, can understand what when the tool isn’t giving you the right answer.

 

Robert Millette