Wednesday, May 31, 2017 8:42 PM

Keeping An Eye On The Gulf Of Mexico

Matthew Holliday

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.