Tropical Depression 25 satellite image
GeoColor satellite image of TD 25 over the western Caribbean at 11:10 a.m. EDT Friday, October 2, 2020. (Image credit: RAMMB/CIRA/Colorado State University)

A Tropical Storm Warning is up for Mexico’s Yucatan Peninsula for the expected arrival on Saturday of Tropical Depression 25, which formed at 11 a.m. EDT Friday in the western Caribbean. Poised to strengthen into Tropical Storm Gamma by Saturday morning, TD 25 is a heavy rain threat to Mexico’s Yucatan Peninsula, Belize, and western Cuba. It poses no threat to the U.S. over the next five days.

Conditions for development of TD 25 are favorable through Saturday, with sea surface temperatures (SSTs) of 30 – 30.5 degrees Celsius (86 – 87°F), light wind shear less than 10 knots, and a moist atmosphere with a mid-level relative humidity of 80%. Satellite images showed that TD 25’s heavy thunderstorm activity was steadily increasing in intensity, areal coverage, and organization as the system moved northwest at about 9 mph. An Air Force hurricane hunter aircraft is to investigate TD 25 on Friday afternoon.

Figure 1
Figure 1. Track forecasts out to 10 days for the Gulf of Mexico from the 0Z Friday, October 2, run of the ensemble forecast of the European model. Most of the forecasts (color-coded by pressure) from the 51 individual members predicted that TD 25 would make landfall over the Yucatan Peninsula and remain trapped in the southwestern Gulf of Mexico. One of the 51 forecasts predicted that TD 25 would become a strong hurricane with a pressure of 960 mb or lower (red colors). (Image credit: weathermodels.com)

Forecast for TD 25

The ridge of high pressure steering TD 25 should keep it moving to the northwest or north-northwest through Sunday, a track on which all of the major computer models agree. This motion should bring TD 25 to the coast of Mexico’s Yucatan Peninsula on Saturday, though it is possible the system could slide just north of Cancun and pass through the Yucatan Channel between Cuba and Mexico. TD 25’s forward motion is expected to slow to less than 5 mph Saturday through Monday, resulting in very heavy rains.

The track of TD 25 next week is unclear, as it will be embedded in a region of weak steering currents. The current model consensus is that TD 25 will be a relatively weak storm steered slowly westwards by the low-level winds. If TD 25 manages to over-achieve and intensify into a hurricane over the weekend, a more northerly path and a potential threat to the U.S. could materialize.

Further complications on predicting TD 25’s track may arise next week as another tropical wave, now moving through the eastern Caribbean, arrives in the western Caribbean. In an 8 a.m. EDT Friday Tropical Weather Outlook, the National Hurricane Center gave this second tropical wave two-day and five-day odds of development of 0% and 30%, respectively.

Conditions for development of TD 25 will become more hostile on Sunday, when the system will encounter a large trough of low pressure extending from Mexico into the southeastern U.S., associated with a cold front that moved through the Gulf of Mexico early this week. This trough will bring high wind shear of 20 – 30 knots to TD 25 Saturday night through Monday. In addition, plenty of dry air over the Gulf of Mexico will interfere with development, as will land interaction with the Yucatan Peninsula.

Because of these obstacles, the models do not indicate that TD 25 will achieve hurricane strength over the next five days. Beyond five days, wind shear is likely to decrease and dry air will lessen, as the cold front and associated trough over the Gulf of Mexico weaken. These factors may allow TD 25 to intensify beyond the next five days.

Figure 2
Figure 2. Predicted rainfall amounts from the 6Z (2 a.m. EDT) Friday, October 2, run of the experimental HAFS model, for the period ending at 3Z Wednesday, October 7. The model predicted that TD 25 would dump more than 10 inches of rain (yellow-brown colors) along portions of Mexican and western Cuban coasts, and more than five inches (orange colors) in central Florida. (Image credit: NOAA/AOML)

Heavy rains possible in Florida

The trough of low pressure that TD 25 will encounter this weekend will also act to shunt tropical moisture from the system to the northeast over Florida. This is a favorable setup for what is referred to as a potential Predecessor Rain Event (PRE), which could bring heavy rain and flooding to parts of central Florida. The experimental HAFS model (Figure 2) is predicting more than five inches of rain over a five-day period for central Florida.

Figure 3
Figure 3. GeoColor satellite image of Hurricane Marie in the northeast Pacific at 11:20 a.m. EDT Friday, October 2. (Image credit: RAMMB/CIRA/Colorado State University)

Impressive category 4 Hurricane Marie churns in the northeast Pacific

In the northeast Pacific, over 1,000 miles west-southwest of Mexico’s Baja Peninsula, Hurricane Marie vaulted to category 4 status with 130 mph winds and a 948 mb central pressure at 11 a.m. EDT Friday morning.

Also see: Extreme events ‘presage worse to come’ in a warming climate

This intensity ties Marie with Hurricane Douglas of July and Hurricane Genevieve of August as the basin’s most intense hurricane of 2020. Marie still has a window of opportunity to intensify into a stronger storm on Friday before crossing into a region of cooler ocean temperatures and higher wind shear that will likely induce significant weakening beginning on Saturday. Marie is not a threat to any land areas.

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Posted on October 2, 2020 (1:27pm EDT).

Jeff Masters, Ph.D., worked as a hurricane scientist with the NOAA Hurricane Hunters from 1986-1990. After a near-fatal flight into category 5 Hurricane Hugo, he left the Hurricane Hunters to pursue a...

45 replies on “Tropical Depression 25 forms in the western Caribbean”

  3. .The experimental HAFS model (Figure 2) is predicting more than five inches of rain over a five-day period for central Florida.

    .
    NWS is apparently in agreement with that for parts of central Florida. NWS Melbourne office has issued flood watches in effect until the morning of Oct. 5, although the focus is mainly over the next 2 days rather than 5.:

    A Flood Watch has been issued for all of east-central Florida,
    except Okeechobee County, through Monday morning. Widespread
    rainfall amounts of 2-4″ with isolated amounts of 6-8″ are possible.
    This heavy rain will produce new flooding or worsen ongoing flooding
    in parts of our area, especially in Martin and St. Lucie Counties.

  5. ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sat Oct 3 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on 
Tropical Storm Gamma, located over the northwestern Caribbean Sea.

1. A tropical wave is producing widespread cloudiness, showers, and 
thunderstorms over the eastern and central Caribbean Sea, with 
locally heavy rainfall and gusty winds affecting portions of the 
ABC Islands, the Lesser Antilles, the Virgin Islands, and Puerto 
Rico.  Environmental conditions are expected to become a little 
more conducive for development, and a tropical depression could 
form next week while the system moves westward or west- 
northwestward at about 15 mph across the central and western 
Caribbean Sea.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...medium...40 percent.

2. Shower activity has increased since yesterday in association with a 
tropical wave located about midway between the coast of Africa and 
the Lesser Antilles.  Some slow development of this system may 
occur during the next several days as it moves generally westward 
to west-northwestward.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

Public Advisories on Tropical Storm Gamma are issued under WMO 
header WTNT35 KNHC and under AWIPS header MIATCPAT5.
Forecast/Advisories on Tropical Storm Gamma are issued under WMO 
header WTNT25 KNHC and under AWIPS header MIATCMAT5.

Forecaster Beven

  8. I noticed in the companion article by Richels et al, the phrase “…hurricanes of unexperienced ferocity…and unpredictability…” ‘Unexperienced’ seems unjustified, as we have had plenty of ferocious storms — Galveston, Labor Day, Camille — and hurricane predictability has never been better.

    Meanwhile we’re getting wet in S. FLA. 🙂

    1. My guess is that the unpredictability they mention is a reference to rapid intensification. Forecasting of storm track and intensity are definitely better than ever, but I think the models still seem to have a lot of trouble with RI.

  11. Thunderstorms have wrapped 75% around the center of TD 25, if this continues I could see rapid intensification happening tonight- low shear, insane oceanic heat content, immense convergence at the lower levels, and upper level anticyclone overhead, which would steer the storm further north and east, creating a situation where it may avoid landfall on the Yucatan and strengthen further. Regardless, life threating flooding rain for Central America and Cuba and the Yucatan and lots of rain for the Florida Peninsula as well.

  13. I wonder if the east Caribbean wave might hit west FL and create a weakness for the bay of Campeche storm (TD) giving FL a 1, 2 punch? Seems strange w/ a front over FL and for being this late in season that the TD would end up so far SW.

    1. Well, SW is where its headed. Ridge building is forcing it to go that way kicking and screaming.

  18. and after the heavy rainfall our east coast and southern FL area’s took yesterday…this storm may turn out to be a Severe flooding event..gee i sure hope not…be safe out there

  19. ok now we all along the gulf coast area’s need to stay a lil More alert till we know for sure where the TD is heading huh..myself im ready with my supplies..ive always had the Plywood cut to form a barrier on my windows etc..and we just bought our food supplies just in case…now lets see where,,this storm wants to go in huh…good luck everyone..might be a long weekend

    1. Are you inviting us…if we pass a weather IQ test…to share your “supplies” this weekend? I will bring some chips and a bottle opener. Perhaps Dr. Jeff and Bob could stop by to provide some expert analyses.

  20. ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Fri Oct 2 2020

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center has initiated advisories on Tropical 
Depression Twenty-Five, located over the northwestern Caribbean Sea.

1. A tropical wave is producing widespread cloudiness, showers, and 
thunderstorms over the eastern Caribbean Sea, with locally 
heavy rainfall and gusty winds affecting portions of the ABC 
Islands, the Lesser Antilles, the Virgin Islands, and Puerto Rico.  
Environmental conditions are expected to become a little more 
conducive for development, and a tropical depression could form next 
week while the system moves westward or west-northwestward at about 
15 mph across the central and western Caribbean Sea.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...medium...40 percent.

Public Advisories on Tropical Depression Twenty-Five are issued 
under WMO header WTNT35 KNHC and under AWIPS header MIATCPAT5.
Forecast/Advisories on Tropical Depression Twenty-Five are issued 
under WMO header WTNT25 KNHC and under AWIPS header MIATCMAT5.

Forecaster Berg

  21. Thank You Dr. Seems to me that a big issue, for the future of the storm, is how intense or weak it will be assuming the core does not make landfall, and it is able to slip into the S Gomex through the Yucatan Channel………..Conditions are currently hostile in the Gulf as you note but a stronger storm would have a better time fighting off typical October climatology. Weak steering and slow movement gives the larger synoptic factors around the storm a chance to change to more favorable, or unfavorable, conditions. Have to see where we are on Sunday and Monday to get a better potential grip.

  22. Thank you SO MUCH for these articles, you are the a vital source for in-depth, knowledgeable meteorological analysis. Keep ’em comin!

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