Atlantic Hurricane Season 2019

Watches in Place. A Tropical Storm Soon to be Born.

Updated July 10, 2019 @3:07 PM EST 

The National Hurricane Center has been keeping a close eye on a disturbance coming down into the Gulf of Mexico from the Deep South for a few days now. July is typically a quiet month for tropical cyclone formation compared to the active months of August through October. The most recent July tropical storm landfall was Tropical Storm Emily, which came ashore in Florida in 2017.

We keep a close eye on one location during this month though and that is the Gulf of Mexico, which usually produces the majority of tropical cyclones during the months of June and July due to the constant warm sea surface temperatures (SSTs). Likely within the next 24 hours these waters will help to intensify “potential tropical cyclone #2” into Tropical Storm Barry.

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Location and Satellite Imagery of Potential Tropical Cyclone #2 in the Gulf of Mexico on July 10, 2019 (Courtesy NOAA)

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GOES Imagery of Potential Tropical Cyclone #2 in the Gulf of Mexico on July 10, 2019 (Courtesy NOAA) 

The National Hurricane Center has given this system a 100% chance of becoming a Tropical Depression and a 90% chance of strengthening into a Tropical Storm within the next 24 hours as it finally moves away from the Florida coast and into the Gulf of Mexico. Now that the center of circulation is over open water it can concentrate on strengthening and taking advantage of the warm SSTs. This system has been delivering heavy rain and thunderstorm activity to the Florida Panhandle over the past couple of days as it slowly moved southward. Most of the cloud and thunderstorm activity from satellite and radar is now secluded to the southern part of the center of circulation, which is to be expected as a storm moves over water. Land interaction helps to break down thunderstorm activity and wrap dry air within the system, this in turn helps to weaken the system. Thunderstorms then become more prominent on one side of the storm, particularly the area that is over open water. The west coast of Florida will be experiencing the extreme outer bands of this system for today which could produce heavy rainfall and a few tornadoes, particularly waterspouts, common for the state of Florida with tropical cyclone activity. However, Florida is not the main area of concern at this time. Western states bordering the Gulf of Mexico, especially Louisiana, should be on high alert for this storm.

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Key Messages for Potential Tropical Cyclone #2 from NOAA

Mississippi and Louisiana have already been receiving heavy amounts of rain from the western side of this system as it continues to strengthen and develop. This rain will continue as this storm becomes more organized. Now that “Potential Tropical Cyclone #2” is over open waters convection will continue producing more clouds and therefore more thunderstorm activity. Clouds will continue to accumulate not only on the western side of the storm (currently affecting Mississippi and Louisiana) but also on the drier east side of the storm which will affect the coastlines of Alabama and extreme west parts of the Florida Panhandle.

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Rain forecast for the next seven days (Courtesy NOAA) 

At this time the main threat with this system will be the rainfall. While over the Gulf of Mexico gaining strength it will continue to hug very close to the coastlines delivering heavy rainfall until this weekend, when it is expect to turn northward and impact land. These forecasts will indeed change over the next few days as this system strengthens and we determine if it will move and track close to land (which could help to weaken the storm) or if it will stay far offshore which could aid in strengthening the storm even further. At this time parts of Louisiana can expect a total of between 15 to 20 inches of rain between today, July 10 and next Wednesday, July 17.

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Potential Track of Potential Tropical Cyclone #2 (Courtesy NOAA)

Tropical Storm Watches have already been issued for coastlines of Louisiana and will likely be upgraded to Tropical Storm Warnings during the nest 24 hours, even hurricane watches and warnings are not out of the question. This storm system is moving fairly slowly at about 8 mph to the WSW. The speed and direction will play a key role in whether this storm rapidly intensifies. First, the slower a storm moves, the longer it has to intensify and take advantage of those warm SSTs. Additionally, coastlines will be enduring the effects for a longer period of time which will increase the flooding and storm surge risks. Second, the direction “Potential Tropical Cyclone #2” is moving: WSW. That southerly direction is pushing the storm further away from land and out into open water. Land interaction helps to weaken a tropical system and prevents it from intensifying. If this storm continues out to sea and away from land there will be a higher chance that this system will rapidly intensify and possibly become a hurricane. At this time, the National Hurricane Center is forecasting that the system will become a Tropical Storm, and adopt the name Barry, by Thursday (likely could become a Tropical Storm by late tonight). It will continue to stay over the open waters of the Gulf until Saturday before approaching the shores of western Louisiana and eastern Texas, and it could very well be a hurricane at the time of landfall.

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Current Sea Surface Temperatures in the Gulf of Mexico for July 10, 2019 (Courtesy NOAA)  

In order for a tropical cyclone to form and strengthen it requires a few ingredients, one being warm SSTs of 26.5 degree C (about 80F). At this time the Gulf of Mexico is well above 26.5 C all across. Off the immediate coast of Louisiana water temperatures can be considered “bath water” with temperatures at 32 C (about 90F). Intense rain and thunderstorm activity, currently over Louisiana is likely being fueled by these warm waters even though the center of circulation is still far to the east of the state. Additionally, tropical cyclones require minimal wind shear in the upper levels of the atmosphere to continue to strength:

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Current wind shear levels in the Gulf of Mexico for July 10, 2019 (Courtesy Track the Tropics)

High wind shear helps to tear apart a tropical cyclone so these systems like to be secluded in a calm environment where upper and lower level winds are not going in separate directions which tear the storms apart. Currently, the Gulf of Mexico is not producing high enough wind shear values that will hinder the strengthening of “Potential Tropical Cyclone #2.”

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Current Wind Shear Areas of Favorability Across the Gulf of Mexico and the North Atlantic (Courtesy Track the Tropics)  

Just off the south coast of the Florida Panhandle there is a pocket of favorable atmosphere for tropical cyclone development and that is where “Potential Tropical Cyclone #2” has settled. Most of the unfavorable wind shear areas are located over Cuba and far out towards Texas giving this system a perfect opportunity to strengthen over this week and into the weekend.

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Spaghetti Plot Showing Model Forecasts on the Direction “Potential Tropical Cyclone #2” will Track 

Most models are in agreement that this soon-to-be Tropical Storm will stay offshore for a few days before interacting with a high pressure system lingering just off the Texas coastline. This high pressure will block this storm from continuing westward into Texas and instead curve the storm northward into the state of Louisiana.. Louisiana is not the only state that will be affected by this storm. Mississippi, Alabama and Florida have already seen heavy amounts of rain from this system and will continue to accumulate more moisture over the next few days, especially Mississippi. Another state that we have to be concerned about will be Texas. True the high pressure system is acting as a shield and preventing the storm from traveling into most of Texas but parts of extreme east Texas will see some impacts. If this storm impact the far west side of Louisiana, Texas will receive heavy rains, flash flooding, and even storm surge – depending on the track and strength. Additionally, once this storm impacts land and moves inland it will likely undergo extratropical transition which will increase the size of the system as a whole as it transforms. When this occurs the rain area expands and will bring additional heavy rain to the Gulf States and even places like Arkansas and Tennessee. Texas and Oklahoma will also experience heavy winds since the winds generally shift to the west side of a tropical system as it undergoes extratropical transition, while the rain shifts eastward.

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Storm Surge Watches and Warnings Currently Issued (Courtesy NOAA) 

The final component that we need to be concerned about at this time is the storm surge that will be accompanying Potential Tropical Cyclone #2. At this time a Storm Surge Watch has been issued for coastlines of Louisiana and these will likely turn into warnings, especially as this storm strengthens over the next few days. Louisiana is no stranger to storm surge, and many residents know that even a Tropical Storm or Category 1 hurricane can easily submerge towns and cities along their coastlines.

Louisiana Gov. John Bel Edwards has already declared a state of emergency Wednesday for all of Louisiana because of the possibility of flooding, winds, and storm surge throughout the state.

“There could be a considerable amount of overtopping of Mississippi River levees in Plaquemines Parish on both the east bank and the west bank,” Edwards said at a Wednesday news conference.

He ordered the Louisiana National Guard to begin deploying soldiers and high-water vehicles to the state’s most vulnerable areas.

Torrential rain up to 18 inches of rain is possible and some areas could even receive isolated values exceeding 20 – 30 inches. At this time the heavy rains are the main threat with this system. Once strengthening takes place with the potential for a hurricane forming, storm surge will then become the next main threat to coastlines.

Blogs will continue to be updated and published regarding this system. For the latest up-to-date information make sure to head on over to @WeatherGoddess on Facebook.


2019 Atlantic Hurricane Season Incoming

Updated May 30, 2019 @ 6:59 pm EST

It is that time of year once again. Sea surface temperatures (SSTs) are rising and wind shear is beginning to lessen. We have one factor so far, the SSTs are prime for hurricane development and survival, but we are experiencing a Spring season with high wind shear values in the atmosphere. This is good news if you do not want to see the formation of hurricanes; bad news if you are not a fan of tornadoes. Two of nature’s most formidable disasters rely on opposite wind ingredients. Hurricanes cannot survive in an environment of high wind shear where winds of different directions and speeds help to tear the structure and convection of the storm apart. Hurricanes prefer a calm wind environment so that thunderstorms can grow without disruption. The warm, moist air over the ocean rises upward leaving less air at the surface. So as this warm-moist air rises and fuels the building thunderstorms, an area of low pressure forms below. The more warm air that travels upward, the stronger the storm, and this powers up the low pressure beneath and allows it to “suck in” surrounding warm-moist air to continue to strengthen.

Tornadoes, on the other hand, thrive on wind shear. In order for a tornado to form it needs warm, moist air (from the Gulf of Mexico, for example) and cool, dry air from the opposite direction (for example, Canada). When these two air masses meet and interact they create instability in the atmosphere. These different winds, from two different directions (this is wind shear) also helps to create a spin in the clouds which produces tornadoes. So while hurricanes are primarily reliant on warm-moist air and very little wind shear; a tornado needs both warm and cold air to create an unstable environment, and powerful wind shear to create that spin in the atmosphere.

What we have been experiencing this past Spring is an active tornado season. There is so much energy and wind shear in the atmosphere that supercell thunderstorms are producing so many tornadoes across the United States. As of this writing, the United States has reported over 750 tornadoes this year of which over 500 of them have been confirmed by the National Weather Service. To put that in perspective, we only had about 470 tornadoes reported during this time last year. With so much tornado activity this year many are wondering if this is a sign as to how active the 2019 Atlantic Hurricane Season will be. There are so many factors to determine that there can never be a precise answer for how active this season will truly be, however, statistically speaking, years that saw an active tornado season yielded a less active hurricane season. This is because of the intense amount of wind shear in the atmosphere which is helping to produce all of these tornadoes. There is another ingredient at play here though, and that is the potential development of an El Niño over the next few months.

An El Niño is a long period change in the climate that can last 2-3 years on average. An El Niño event begins off the west coast of South America where SST’s begin to rise above normal. This large scale change affects weather patterns worldwide, especially hurricane formation. The Pacific becomes warmer and we typically see a surge in tropical storm development because of these hotter SSTs. However, in the Atlantic we have the opposite; SSTs become cooler than normal and wind shear values begin to increase for large portions of the Atlantic preventing the formation of hurricanes.

The National Oceanic and Atmospheric Administration (NOAA) says that “a weak El Niño is underway in the tropical Pacific, and it’s likely to continue through summer (70% chance) and fall (55-60% chance). Weak events can still produce moderate or strong impacts in some places, but such impacts are less likely overall.”

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Images above: Global SST’s currently. First image is the current SSTs for May 30 (Courtesy Weather Underground). Second image is the change in the average temperature of sea water compared to the 1981-2010 time frame (Courtesy NOAA). 

As a whole, Earth’s SSTs are higher compared to the 20 year period from 1981-2010. So yes, we are experiencing warmer than average SSTs across the world. However when identifying an El Niño event, we are not seeing a strong indication of warmer SST’s off the west coast of South America compared to the Pacific Ocean as a whole at this current time (see first image above). Extending from the northwest coast of South America we see a swirl of orange and yellow colors pushing their way westward towards Asia. This is the area we look at to confirm an El Niño taking place, and because these waters are cooler than the surrounding waters we can say that we are in a very weak El Niño stage for the moment. It is possible that these waters will continue to warm over the Summer and Fall and this will indicate a stronger El Niño. However, climatologists and meteorologists are in a general agreement that this year will see more of a weak El Niño taking place. So what does this mean for the upcoming Atlantic Hurricane Season?

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First Image: The National Hurricane Center’s forecast for the 2019 Atlantic Hurricane Season (Courtesy NOAA). Second Image: Colorado State University’s 2019 Atlantic Hurricane Season forecast (Courtesy CSU). 

Both the National Hurricane Center and Colorado State University are calling for a near-average hurricane season this 2019 in the Atlantic. Likely the factors taken into consideration were the developing El Niño and the warmer SSTs as a whole around the world. Even if this weak El Niño persists into the Summer and Fall it will likely not have enough strength to affect the development of hurricanes as a whole. With the Atlantic already being above average in temperature the past few years the cooling affect that an El Niño would generally delivers to the Atlantic Basin will probably not be enough to bring down the temperatures very much. Therefore, even though we are classified to be in a weak El Niño phase we are currently not seeing any strong effects from this climatological pattern, hence why forecasters are likely going with a near-average hurricane season. However, I have stated this for many years: It only takes one hurricane. We can forecast hurricane numbers each year but we cannot forecast the track of these systems. Agencies may “only” be calling for 2-4 major hurricanes this year but that does not mean they will stay out at sea and not bring any impact to us. The past three years have been deadly for the United States and reminded many of us that we are very vulnerable to these powerful systems. Hurricane’s Matthew, Irma, Florence, Maria, Harvey, and Michael, have all shown us these past few years how deadly a hurricane can be and that we must always be prepared no matter what forecasts say.

However, another topic to quickly discuss was the formation of Subtropical Storm Andrea (ignore the subtropical part, it is still a “tropical storm”).

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Images above are the track and satellite imagery of Subtropical Storm Andrea

For the fifth straight year in a row we have had our first named system take place outside of the official Atlantic Hurricane Season (June 1 – November 30). Andrea was a weak system just to the southwest of Bermuda when it gained enough strength to be dubbed a “subtropical storm” on May 20. Unfortunately it only lasted about 0.75 days before it dissipated from intense wind shear on May 21, 2019. Andrea is an example that even though a weak El Niño is in place, there is still enough energy in the atmosphere to have a storm form, even if it was “alive” for less than a day.

The official start of the Atlantic Hurricane Season is less than two days away and meteorologists across the United States, Mexico, and Caribbean will have their eyes on the Atlantic and Gulf of Mexico as the season begins. Currently the Atlantic is quiet partly due to the intense wind shear in the atmosphere across the warm tropical regions hurricanes generally like to grow and develop in:

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Image above: Current wind shear areas in the North Atlantic Basin (Courtesy CIMSS)

Referring to the image above, red areas indicate high wind shear and thus “unfavorable” for tropical cyclone development. It is clear that most of the tropical regions and the Gulf of Mexico are experiencing high wind shear at this time. This is generally typical for the month of June as we are phasing from Spring into Summer. However, this also gives a clear indication on why the United States, and especially The Plains have been experience one tornado after the next. With so much of the United States under high wind shear these thunderstorms are getting plenty of wind energy to help form these tornadoes.

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Image above: Typical tropical tracks and origins for Tropical Storms that form in the month of June.

Over the next month we could see wind shear die down slightly giving a chance for a couple of storms to develop. However, June is a quiet month usually for tropical storm development, as well as the month of July. Since 1951, only 13 percent of tropical storms formed in June and July combined. August, September, and October (the active months) have accounted for 24, 36 and 21 percent of all tropical storms on record, respectively (Dolce, 2019). If a storm does form, however, they are usually found in the Gulf of Mexico where the SSTs remain warm for most of the year and do not need as much time to continue to warm as we transition from a cool Spring into a hot Summer. We will have to wait and see how the month of June plays out and what this hurricane season will have in store for us this 2019. Weather Goddess, Dr. Athena Masson will be keeping a close eye on the Atlantic for the next storm.

 

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