SUMMARY OF 1100 AM EDT
LOCATION…16.9N 79.2W
ABOUT 115 MI…180 KM SSW OF NEGRIL JAMAICA
ABOUT 210 MI…340 KM SE OF GRAND CAYMAN
MAXIMUM SUSTAINED WINDS…35 MPH…55 KM/H
PRESENT MOVEMENT…NW OR 325 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…1005 MB…29.68 INCHES
WATCHES AND WARNINGS
CHANGES WITH THIS ADVISORY:
The government of the Cayman Islands has issued a Tropical Storm Warning for the Cayman Islands, including Grand Cayman, Little Cayman, and Cayman Brac.
The government of Cuba has issued a Tropical Storm Warning for the Cuban provinces of Matanzas, Mayabeque, Havana, Artemisa, Pinar del Rio, and the Isle of Youth.
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
A Tropical Storm Warning is in effect for…
- Cayman Islands
- Cuban provinces of Matanzas, Mayabeque, Havana, Artemisa, Pinar del Rio, and the Isle of Youth
A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area within 36 hours.
Interests elsewhere in central and western Cuba, in the northern Yucatan Peninsula, and along the northern U.S. Gulf coast should monitor the progress of this system.
For storm information specific to your area, please monitor products issued by your national meteorological service.
DISCUSSION AND OUTLOOK
At 1100 AM EDT (1500 UTC), the center of Tropical Depression Nine was located near latitude 16.9 North, longitude 79.2 West. The depression is moving toward the northwest near 13 mph (20 km/h), and this general motion should continue over the next few days. On the forecast track, the center of the depression will pass near of over the Cayman Islands tonight, the Isle of Youth and Western Cuba Friday, and move over the southeastern and central Gulf of Mexico Friday night and Saturday. The system is forecast to approach the U.S. northern Gulf coast on Sunday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Steady strengthening is forecast during the next few days. The depression is expected to become a tropical storm tonight, and become a hurricane when it is near western Cuba or over the southeastern Gulf of Mexico. Additional strengthening is likely over the Gulf of Mexico and the system could be near major hurricane strength when it approaches the northern Gulf coast.
The estimated minimum central pressure is 1005 mb (29.68 inches).
HAZARDS AFFECTING LAND
STORM SURGE: A dangerous storm surge will raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore flow along the immediate coast of the Isle of Youth and near and to the east of where the center crosses the coast of western Cuba. Near the coast, the surge will be accompanied by large and destructive waves.
WIND: Tropical storm conditions are expected in the Cayman Islands tonight, and are expected to reach the Isle of Youth and portions of western Cuba in the warning area on Friday.
RAINFALL: The depression is expected to produce total rainfall accumulations of 6 to 10 inches with maximum totals of 15 inches across Jamaica. Rainfall totals of 8 to 12 inches with isolated maximum amounts of 20 inches are expected across the Cayman Islands, western Cuba, including the Isle of Youth and the northeast portions of the Yucatan Peninsula. These rainfall amounts may produce life-threatening flash floods and mudslides.
Rainfall from this system is likely to begin impacting portions of the central U.S. Gulf Coast by early Sunday.
SURF: Swells generated by this system will begin affecting Jamaica, the Cayman Islands and Cuba tonight and Friday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.
MODEL DATA
Her eis just a brief look at some of the model data that is showing landfall across the Louisiana coast as well as some intensity guidance highlighting the potential for a Major Hurricane at landfall.
Both graphics are pulled from LEvi Cowan’s website, Tropical Tidbits.
There are two parts of this path that will, in the end, dictate the final path. They are circled on the image below. The southern circle is the response to the system (a) developing and (b) interacting with the departing upper-level low that is moving across the Gulf currently. The northern circle is a reflection of the periphery of the ridge of high pressure and how the system ‘makes the turn’ around the edge of that periphery.
The more interaction in the short term will pull the system to the Northeast. And a larger ridge will push the system a bit more West when ‘making the turn’ north.
Any extra interaction / nudge northeastward will change how TD9 develops. Comparing the chart of potential intensities below to the paths above, the paths that pull the system on the north side of the tracks, tend to keep the system weaker. The tracks that keep it a bit farther south allow it to grow into a Major Hurricane.
The only thing that throws a wrench into that forecast data is the water temperatures of the Gulf of Mexico.
The loop current that is plopped in the middle of the Gulf and just northeast of the forecast track. So any shift to the northeast would result in a system traveling over the very warm loop current.
NHC DISCUSSION
Early morning visible satellite imagery shows that the circulation associated with the area of low pressure over west-central Caribbean Sea has become better defined. There has also been an increase in the organization of the associated convective activity, and based on consensus Dvorak T-numbers of 2.0 from TAFB and SAB, advisories are being initiated on a tropical depression.
The initial intensity is set at 30 kt, in agreement with the subjective satellite estimates. The official reporting station in Kingston, Jamaica, has reported sustained winds of 25 kt with gusts to 35 kt during the past couple of hours. An Air Force Reserve reconnaissance aircraft is scheduled to be in the system later this afternoon to provide more information on the system’s structure and intensity.
The depression is moving northwestward or 325/11 kt, however the initial motion is a bit more uncertain than normal since the low-level center has only recently formed. The cyclone is forecast to move steadily northwestward around the southwestern portion of a deep-layer ridge centered over the western Atlantic.
This track should bring the center near or over western Cuba late Friday, over the southeastern and central Gulf of Mexico Friday night and Saturday, and have the center approach the northern Gulf coast on Sunday. The track guidance is in relatively good agreement, however the average NHC track forecast error at day 4 is around 175 miles, so users should not focus on the details of the long range track forecast.
Some shifts in the track are likely until the system consolidates and becomes better defined. The NHC track is near the various consensus model aids and is in best agreement with the GFS ensemble mean.
The depression will be moving over the high ocean heat content waters of the northwestern Caribbean Sea during the next 24-36 hours. This, in combination with low vertical wind shear and a moist environment, should allow for steady strengthening. The depression is forecast to become a tropical storm later today or tonight, and could approach hurricane strength as it passes near or over western Cuba.
Once the system moves into the Gulf of Mexico, conditions are expected to be conducive for additional strengthening, and rapid intensification is explicitly shown in the NHC forecast between 48 and 72 hours. The NHC intensity forecast brings the system near major hurricane strength when it approaches the northern Gulf coast on Sunday. This forecast is supported by the HWRF and CTCI models, and the GFS, ECMWF, and UKMET global model guidance, which all significantly deepen the cyclone over the Gulf of Mexico.
As a result, there is higher-than-normal confidence that a strengthening tropical cyclone will be moving over the Gulf this weekend.
Key Messages:
- Tropical storm conditions are likely in portions of the Cayman Islands tonight and western Cuba Friday and Friday night, with dangerous storm surge possible in portions of western Cuba, including the Isle of Youth, in areas of onshore flow.
- The system is expected to produce life-threatening heavy rains, flash flooding and mudslides across Jamaica, the Cayman Islands, western Cuba, including the Isle of Youth and northeastern portions of the Yucatan Peninsula.
- This system is forecast to approach the northern Gulf Coast at or near major hurricane intensity on Sunday, although the forecast uncertainty is larger than usual since the system is just forming. There is a risk of life-threatening storm surge, damaging hurricane-force winds, and heavy rainfall Sunday and Monday along the northern Gulf Coast from the Florida Panhandle to the upper Texas coast, with the greatest risk along the coast of Louisiana. Interests in these areas should closely monitor the progress of this system and ensure they have their hurricane plan in place.
FORECAST POSITIONS AND MAX WINDS
INIT 26/1500Z 16.9N 79.2W 30 KT 35 MPH
12H 27/0000Z 18.2N 80.4W 35 KT 40 MPH
24H 27/1200Z 20.3N 82.0W 45 KT 50 MPH
36H 28/0000Z 22.5N 83.9W 55 KT 65 MPH…INLAND
48H 28/1200Z 24.4N 86.0W 65 KT 75 MPH…OVER WATER
60H 29/0000Z 26.1N 88.1W 80 KT 90 MPH
72H 29/1200Z 27.7N 90.0W 95 KT 110 MPH
96H 30/1200Z 30.5N 92.0W 70 KT 80 MPH…INLAND
120H 31/1200Z 33.7N 91.2W 30 KT 35 MPH…INLAND
