PTC5 Has Become Tropical Depression Five; Likely to Become Elsa on Thursday Morning

| June 30, 2021 @ 10:11 pm

SUMMARY OF 1100 PM AST…0300 UTC…INFORMATION
LOCATION…9.6N 46.3W
ABOUT 1020 MI…1645 KM ESE OF THE WINDWARD ISLANDS
MAXIMUM SUSTAINED WINDS…35 MPH…55 KM/H
PRESENT MOVEMENT…W OR 280 DEGREES AT 23 MPH…37 KM/H
MINIMUM CENTRAL PRESSURE…1008 MB…29.77 INCHES

SUMMARY OF WATCHES AND WARNINGS IN EFFECT
A Tropical Storm Warning is in effect for…
* Barbados
* Martinique
* St. Lucia

A Tropical Storm Watch is in effect for…
* St. Vincent and the Grenadines
* Guadeloupe

FORECAST DISCUSSION
The satellite presentation of the system over the last 6-12 hours has continued to gradually improve, with a prominent banding feature to the west of the estimated center. An ASCAT-A pass received at 2323 UTC revealed that the low-level circulation has become a bit better defined compared to earlier today, though still somewhat elongated to the south and west. The peak wind retrievals from this instrument were 30-32 kt. While subjective satellite estimates from TAFB and SAB were a bit higher, the latest estimated intensity was held at 30 kt for this advisory in agreement with the slightly lower scatterometer data.

The initial motion has accelerated a bit tonight at 280/20 kt. A strong subtropical ridge is situated poleward of the tropical depression, and this feature should steer the system quickly to the west-northwest over the next several days. After 72 hours, the tropical cyclone will reach the westward extent of the ridge and begin to move more poleward and slow down as the ridge also becomes eroded by a mid-latitude trough to over the eastern US. The track guidance in the latter portion of the forecast continues to exhibit large spread, with the GFS and HWRF/HMON models along the left side of the guidance envelop, while the ECMWF and its ensemble mean on the right side. The latest NHC track forecast is a shade right of the previous one, and also slightly faster, but given the spread in the models, the latter portion of the track is more uncertain than usual.

While the depression is currently in a favorable environment of low vertical wind shear, warm sea-surface temperatures, and high mid-level relative humidity, the expected acceleration in forward motion could cause the system to outrun the favorable upper-level easterlies currently overhead, after 36 hours. In addition, the system could be near or over some of the Greater Antilles in the latter portions of the forecast. For these reasons, the intensity remained capped at 50 kt after 36 hours, and is still on the lower end of the intensity guidance suite, though this forecast could be somewhat conservative.

KEY MESSAGES
1. The tropical depression is expected to become a tropical storm before reaching the Lesser Antilles, and tropical storm conditions are expected beginning late Thursday night in portions of the Windward and southern Leeward Islands.

2. Heavy rainfall will move quickly across the Windward and southern Leeward Islands, including Barbados, on Friday. Isolated flash flooding and mudslides are possible.

3. There is a risk of wind and rainfall impacts in portions of the Virgin Islands, Puerto Rico, Hispaniola, Cuba, the Turks and Caicos and the southeastern Bahamas through early next week. Interests in these areas should monitor the system’s progress and updates to the forecast.

4. Interests in Florida should monitor updates to the forecast for this system, but it is too soon to determine what if any impacts could occur there next week given the uncertainty in the long-range forecast.

Category: ALL POSTS, Tropical

About the Author ()

Scott Martin is an operational meteorologist, professional graphic artist, musician, husband, and father. Not only is Scott a member of the National Weather Association, but he is also the Central Alabama Chapter of the NWA president. Scott is also the co-founder of Racecast Weather, which provides forecasts for many racing series across the USA. He also supplies forecasts for the BassMaster Elite Series events including the BassMaster Classic.

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