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Tropical Storm Elsa Forecast Discussion Number 20
2021-07-05 10:33:00| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Mon Jul 05 2021 000 WTNT45 KNHC 050832 TCDAT5 Tropical Storm Elsa Discussion Number 20 NWS National Hurricane Center Miami FL AL052021 500 AM EDT Mon Jul 05 2021 Elsa appears to be holding steady in strength while moving just south of central Cuba. Radar data from Cuba and satellite images show a persistent area of deep convection over the center and some banding features, especially on the south side of the circulation. An ASCAT pass from around 0130Z indicated that Elsa was a compact system with tropical-storm-force winds mostly confined to a region within about 60 n mi east of the center. Peak winds in the pass were around 50 kt in the northeastern quadrant, and given the small size of the cyclone and somewhat course resolution of the ASCAT data, it seems very reasonable that Elsa has an initial intensity of around 55 kt. This intensity estimate is also in line with the latest Dvorak classifications. The NOAA Hurricane Hunters will be investigating Elsa again shortly, and the data the plane collects will be valuable in assessing the storm's intensity and wind field. The tropical storm is moving northwestward at about 12 kt on the southwestern periphery of a subtropical ridge located over the central Atlantic. A gradual turn to the north is expected over the next day or two as Elsa moves in the flow between the ridge and a mid- to upper-level low over the northern Gulf of Mexico. This steering pattern should take the core of Elsa across central or western Cuba later this morning, near the Lower Florida Keys tonight or early Tuesday, and then along or very near the west coast of Florida later on Tuesday through early Wednesday. Most of the models show Elsa moving inland over west-central or northern Florida, but given the expected parallel motion to the coast, much of the west coast of the state will likely see impacts from Elsa on Tuesday and into Wednesday. After Elsa clears Florida, it is expected to move faster north-northeastward across coastal Georgia and the Carolinas Wednesday and Thursday before moving over the western Atlantic. The new track forecast is just a little to the left of the previous one to be in better agreement with the latest consensus models. Given the overall favorable environmental conditions, Elsa could strengthen a little before it reaches the coast of Cuba later this morning. Some weakening is expected due to the land interaction with Cuba, but most of the model guidance suggests that Elsa could restrengthen slightly before it moves inland over Florida. Significant strengthening is not anticipated though due to moderate wind shear. However, it should be noted that given the expected track, much of the west coast of Florida will be on the east side of Elsa, which is where the strongest winds, highest surge, and heaviest rains are expected to be. Gradual weakening is forecast while Elsa moves across portions of the southeast U.S., but some restrengthening is possible again when the storm moves over the western Atlantic. The NHC intensity forecast is a little higher than the previous one while Elsa is expected to be over the Gulf of Mexico, and it lies near the high end of the model guidance. Key Messages: 1. Heavy rain will impact the Cayman Islands and Cuba today resulting in significant flooding and mudslides over Cuba. As Elsa approaches the Florida Keys, Florida Peninsula, and coastal Georgia Monday through Wednesday, heavy rainfall may result in isolated flash, urban, and minor river flooding. Mid to late week, heavy rains across coastal South Carolina and North Carolina may result in isolated flash and urban flooding. 2. Tropical storm conditions and a dangerous storm surge are expected to continue across portions of central and western Cuba today. Hurricane conditions are also possible along the south coast this morning. 3. Tropical storm conditions are expected in portions of the Florida Keys and southwestern Florida tonight and Tuesday, where a Tropical Storm Warning is in effect. A Tropical Storm Watch and a Storm Surge Watch are in effect for much of the west coast of Florida. 4. There is a risk of tropical storm conditions and storm surge impacts along the coasts of Georgia and the Carolinas Wednesday and Thursday. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 21.0N 79.9W 55 KT 65 MPH 12H 05/1800Z 22.2N 81.3W 55 KT 65 MPH...INLAND 24H 06/0600Z 23.9N 82.5W 50 KT 60 MPH...OVER WATER 36H 06/1800Z 25.9N 83.2W 55 KT 65 MPH 48H 07/0600Z 28.0N 83.4W 55 KT 65 MPH 60H 07/1800Z 30.1N 83.0W 45 KT 50 MPH...INLAND 72H 08/0600Z 32.5N 80.9W 35 KT 40 MPH...INLAND 96H 09/0600Z 36.8N 74.3W 40 KT 45 MPH...OVER WATER 120H 10/0600Z 42.0N 64.3W 40 KT 45 MPH...POST-TROP/EXTRATROP $$ Forecaster Cangialosi/Reinhart
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