June 17, 2024 Tropical Update: Southern Gulf of Mexico

Watching Gulf of Mexico for a weak tropical storm development by Friday

Jun 17, 2024

Headlines for the Week

2 areas of interest in the Atlantic in the southern Gulf of Mexico and off the SE U.S. coastline — still waiting on Alberto and Beryl. No activity in the Eastern Pacific so far in 2024 — unusual.

A Central American Gyre (CAG) continues to rotate deep tropical moisture out of the Caribbean into the Gulf of Mexico and will drive the weather for the next 7-10 days.

The CAG will help fuel the development of the “heat dome” or downstream ridge.

The Texas and the Gulf Coast into Louisiana will be drenched with excessive/flooding rain.

A massive, long-lasting and potentially record setting June heat dome is building over the Northeast and Mid-Atlantic in response to a trough digging out west.

The ridge will force a tropical moisture plume from the “gyre” to go around to the north and provide the Midwest — especially Minnesota with boatloads of rain.

Invest 91L: First area being watched in the 48-hour and 7-day range in the southern Gulf of Mexico for likely tropical cyclone development: 70%

1. Southern Gulf of Mexico
Satellite imagery and surface observations indicate that a broad area of low pressure is forming over the Bay of Campeche. 

Environmental conditions appear conducive for additional gradual development, and a tropical depression or tropical storm is likely to form by midweek while it moves slowly W or WNW toward the western Gulf coast.

An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate the 
system later today.

* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

The MSLP of 1002 mb with a large, broad circulation center is all the ECMWF 00z could muster for Invest 91L.

Central American Gyre

The relative vorticity at 850 hPa (low-levels) highlights the “spin” or convective elements over and around Central America aided by “gap flow” through the Gulf of Tehuantepec. This allows the transport of deep tropical moisture from the Eastern Pacific into the Gulf of Mexico — the opposite situation when cold fronts from the north during winter typically blast cold, dry air into the Pacific from the Gulf of Mexico.

Note the little blob arriving along the SE Coast rom the Atlantic by late Thursday. That may provide enough of a spin and convection for a weak TD or TS, but the way this season is going so far, I’d not bet much.

The southern Gulf of Mexico is the best chance for storm development although any system would be slow to organize. However, within the larger gyre, convective elements could rapidly intensify upon approach to the coast on Thurs/Fri.

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The relative vorticity associated with the tropical wave or disturbance east of the Bahamas does not develop significantly but could have enough organization eventually for a TD to form.

2. Southwestern Atlantic Ocean

An area of cloudiness and thunderstorms located several hundred miles east of the Bahamas is associated with a surface trough and an upper-level area of low pressure.  
Environmental conditions could be conducive for some development of this system during the next few days while it moves westward or west-northwestward.  The system is forecast to approach the coast of the southeast United States on Thursday or Friday.

* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...30 percent.

10-Days Integrated Vapor Transport

The atmospheric river diagnostic called Integrated Vapor Transport (IVT) works nicely in the tropics to highlight the convergence of deep tropical moisture into plumes.

Next 10-days from ECMWF of IVT:

Southern Gulf of Mexico system (Mon-Tues): 70% chance
Tropical wave arriving into North Florida (Thursday): 30% chance
Heavy rain on the western side of the Heat Dome in the Upper Midwest

Synoptic Analysis [June 17, 2024 06Z]

Heavy Rainfall over Central America and Mexico, and gale warning
over the Gulf of Mexico:

A broad area of low pressure is centered over northern Central 
America and southern Mexico. This area of low pressure will shift
W to WNW toward the western Gulf coast over the next few days. 
Environmental conditions appear conducive for a tropical cyclone 
to develop from this broad circulation, and a tropical depression 
or tropical storm is likely to form by midweek while it moves 
toward the western Gulf coast. There is currently a medium chance 
for TC genesis in the next 48 hours and a high chance for TC 
genesis in the next 7 days.

This broad area of low pressure is known as a Central American 
Gyre (CAG), and often persists for several days.

2 TROPICAL WAVES...

The axis of an Atlantic Ocean tropical wave is near 27W, from 16N
southward, moving westward 10 knots to 15 knots. Scattered
moderate to isolated strong convection is where the wave is
interacting with the monsoon trough.

The axis of an Atlantic Ocean tropical wave is near 60W/61W, from
16N southward, moving westward 10 knots to 15 knots. Scattered
moderate convection is east of the wave axis from 06N to 16N
between 52W and 60W.

Basin Wide IR Satellite Imagery

Note the thick sand/dust plume with a new strong SAL / African dust layer coming off the continent — reference NASA GEOS5 dust extinction.

Scattered convection across the southern Gulf and over the Yucatan will take a while to organize — if it does — into a tropical cyclone by Friday before moving into northern Mexico. Heavy rainfall will also impact Texas coastline including Houston.

Saharan Dust Layer Next 10-days

The Saharan Air Layer with African Dust will continue to shroud the central Tropical Atlantic in the Main Development Region putting a lid on tropical development.

Next 15-Days EPS Ensemble Tropical Storm Tracks

Only show in town is the Gulf of Mexico during the next 15-days — with one ensemble showing a MDR hurricane (2% chance).

Precipitation Anomaly Next 15-days [inch]

The Gulf of Mexico is the focus of exceptional rainfall over the next 10 to 15-days associated with tropical moisture feed on periphery of the gyre. Otherwise, very dry across the Ohio Valley and Mid-Atlantic.

NOAA WPC Precipitation Next 7-days

Scant rainfall under the heat dome over the next 7-10 days.

Enormous rainfall totals for the Texas Gulf Coast but also up to 5” into San Antonio. All of this rainfall is VERY welcome across the Lone Star State.

Eastern Pacific Tropical Weather Outlook

1. Offshore Central America (EP90):

An area of low pressure associated with disorganized showers and 
thunderstorms has moved inland over Central America and further 
development is not expected.  


* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 7 days...low...near 0 percent.

Otherwise, the 15-day Ensembles from ECMWF are almost a blank slate for developing tropical cyclones. Amazingly quiet until the end of June.

June is usually a busy month in the Eastern Pacific, but not this year — yet to see a named tropical storm.

Western Pacific Tropical Weather Outlook

Ghost town — No Suspect Areas areas of interest during the next 48-hours to 7-days from JTWC.

ECMWF EPS ensembles show a few members with a hint of a TC track over the next 10-days in the South China Sea. The last week of June could see development east of the Philippines.

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