Disturbance in the Gulf of Mexico Will Bring Heavy Rain and Muggy Weather

Ridging has continued to build over the southeastern quadrant of the United States over the last few days, which has been responsible for a large region of anomalously hot temperatures and drier air. This ridge is currently centered over eastern Arkansas and western Tennessee but will begin to split as a mid-to-upper level closed low moves from the eastern Gulf of Mexico and into the Southeast early next week. Given that ridging is associated with sinking air which often limits storm development, the splitting of this ridge will result in a drastic change in sensible weather conditions in the coming days.

The National Hurricane Center has outlined a disturbance in the eastern Gulf of Mexico and is giving it a 40% of tropical or subtropical development over the next 5 days. Even though the Atlantic hurricane season doesn’t technically begin until June 1, it wouldn’t be a big surprise to see a weak subtropical/tropical disturbance develop, if convection (thunderstorm development) can consolidate over a small enough region in the Gulf. The upper-level trough/closed low (the feature that is splitting the ridge over the Southeast) will continue interacting with a region of broad surface low pressure moving into the Gulf, which should assist in its further development since the upper-level dynamics will be supportive. Whether or not we get our first named system out of this is not necessarily important from a sensible weather standpoint. The impacts will be about the same regardless, which is what the primary focus should be on.

5-day NHC tropical outlook

Let’s talk about potential impacts and how the weather should change compared to last week/this weekend. The mid-south (Louisiana, Arkansas, most of Mississippi, most of the Southern Plains, and areas just northward) will remain quite toasty for a large part of the week since the closed low and developing surface low should remain to the east/southeast of those regions. However, farther east, temperatures should be cooler due to enhanced rainfall for most of the week, but the transport of deeper moisture into the area will result in muggy conditions, making temperatures feel warmer. Instead of trying to put all of this into words, take a look at the map from the Weather Prediction Center (NOAA) that shows the projected rainfall totals over the next 5 days. Don’t focus as much on exact amounts, but take note if you’re located in a region that is expected to get more than a couple of inches of rain (purplish/reddish-shaded regions).

5-day wpc rainfall forecast

The big impact will be the heavy rainfall, although that’s not necessarily a bad thing since many areas have recently been dry. However, be wary if flash flooding begins to occur and do not attempt to drive over any flooded roadways. As the rainfall map indicates, heaviest rainfall totals over the next several days should occur from Florida through Georgia, parts of Alabama, the Carolinas, and up the East Coast. Another zone to keep an eye on will be from the Ohio Valley into the Mid-Atlantic, where a frontal boundary will remain stalled out over the region. Given that this region is located along the periphery of the current ridge, winds have been westerly/northwesterly through a deep layer of the atmosphere, and disturbances will continue to be embedded within the westerlies, so storminess may be a bit more intermittent and hit-or-miss across that area. Also, this is where the severe weather threat (mainly a damaging wind threat) will be concentrated this week, along with a severe weather threat across parts of the Great Plains. Firsthand Weather will address those risks on a day-to-day basis. Partially due to the moistening of the environment through a deep layer farther south across the Southeast, this should mostly limit the severe weather risk, since temperatures will not decrease with height as rapidly (resulting in lower instability). We’ll still keep an eye on it just in case though.

To briefly summarize, expect a change in weather conditions across a large region. Many will be transitioning from a dry and hot pattern to a warm, muggy, and wet pattern. Given the position of the large ridge, the low in the Gulf of Mexico will not be in a hurry to move out and will have to be swept out by an incoming trough later in the week. This is particularly important information to keep in mind if you intend on hitting the water for fishing or other watersports activities. These towers way north of Key West in the gulf are a prime location for fishing but will be buffeted by the weather so be sure to stay safe. In the meantime, get used to the wet (or at the least, muggy) weather!

Tropical Depression 16 expected to strengthen

Tropical Depression 16 formed earlier today down in the Central American region of the Caribbean.   Tropical Storm Warnings are in effect for portions of Nicaragua and Honduras at this time with the expectation that 16 will strengthen into the next named storm, which would be Nate.

Current environmental conditions are good for development.  16 is sitting in an area of low shear and the sea surface temperatures in the region are very warm.

With the lone exception of colder waters along the coastlines, water temperatures are a warm 29 degrees Celsius over much of the Gulf of Mexico.  The one inhibiting factor in all of this, will be the land interactions that 16 will make.   Landfall is expected along Nicaragua and Honduras, and even if 16 does not make another landfall, he will still pass close to the Yucatan Peninsula and Western Cuba before entering the gulf.  These interactions could prevent major intensification before the gulf.

Hurricane Hunter aircraft did perform a recon mission earlier today, showing a closed and well defined center of circulation.  While there isn’t much deep convection near the center, tropical banding is strong with this system.

Once in the gulf, 16 is forecast to become a hurricane.  The current forecast brings what would be Hurricane Nate towards the Florida Panhandle, as shown below, but anywhere from Louisiana to Northern Florida should be watching this system.  Current model tracks have a wide area due to the impact of a tropical low that moves past Florida.  This low is given a small chance to develop into a tropical system itself, but the strength of this feature will play a role in the future track of 16.

Tropical

Early preparations should  begin soon for those along the gulf coast.  Having a few extra batteries or a bottle of water around is never a bad thing and it’s much better for everyone if they are purchased in advance.  Stores will place larger orders for products if people are buying them.

 

Robert Millette

Keeping An Eye On The Gulf Of Mexico

It’s that time of year again! Tomorrow is the official start of the Atlantic hurricane season, and we’re already going to have to keep a close watch on the Gulf of Mexico next week. While not as common, it’s not unheard of to have a June tropical system develop in the Gulf of Mexico or western Caribbean.

First, let’s talk about the tropical depression off the southwestern coast of Mexico. Tropical Depression Two-E currently has sustained winds of 35 mph and is moving slowly northeastward towards Mexico. This system is quite disorganized, although some strengthening could occur. Given how mountainous the terrain is just off the coast of Mexico near the potential impact zone, this will keep this depression weak, but flooding could be a big issue across the region.

tropical depression two-e

While this depression will not make it across Mexico as is, the overall pattern is going to be favorable for the advection of deep, tropical moisture into the Gulf of Mexico from the eastern Pacific. Precipitable water values will be increasing through the remainder of the week, particularly across the western and central Gulf of Mexico. Precipitable water content values simply indicate how much rain would fall if all moisture were to precipitate out of a vertical column of air extending from the surface to the top of the atmosphere. The higher the values; the wetter the air mass.

As mentioned on Firsthand Weather earlier this week, a mid to upper level trough is going to develop and dig across the eastern U.S. early next week. This feature will be responsible for bringing an unseasonably cooler air mass across the region, which will ultimately result in below average temperatures all the way to the Gulf coast (and yes, even a less humid air mass for many!). Associated with this trough and its embedded shortwaves will be a surface low pressure system that will develop and move to the East Coast sometime early to mid next week. In the image below, you can see the cold front that will extend to the Gulf coast from the surface low along the East Coast. Early in the hurricane season, it’s not uncommon to have tropical activity develop along a frontal boundary that has made it to the Gulf of Mexico. It acts to enhance convection, and if other factors are favorable, some organized development can happen.

Cold front moving through U.S

Mean sea level pressure will generally be on the decline across the Gulf of Mexico from this weekend onward into next week. The first image that I have included below indicates above average sea level pressure across much of the Gulf of Mexico currently, but surface pressure values will drop towards the weekend, which is shown in the image below that. This is a more favorable environment for tropical development.

Gulf of Mexico mean sea level pressure this week

Gulf of Mexico mean sea level pressure next week

While it’s difficult to say whether or not we’ll have a tropical depression or storm in the Gulf of Mexico by later this weekend into next week, the main focus should be on the flooding situation that could evolve as a result of this setup. With the cold front moving southward along the Gulf of Mexico and with a mid to upper level trough positioned over the eastern U.S., this would generally favor any system, whether fully organized or not, moving along the Gulf coast and into Florida. Again, the main focus needs to be on the moisture-rich environment and overall setup that could result in heavy rains from Louisiana to much of Florida. Basically, those located along the Gulf coast and just north (this’ll depend on the placement of the frontal boundary) need to keep an eye on the flooding situation that could evolve this weekend into next week.