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Hurricane Elsa Forecast Discussion Number 12
2021-07-03 10:38:44| National Hurricane Center (Atlantic)
Issued at 500 AM AST Sat Jul 03 2021 000 WTNT45 KNHC 030838 TCDAT5 Hurricane Elsa Discussion Number 12 NWS National Hurricane Center Miami FL AL052021 500 AM AST Sat Jul 03 2021 Elsa appears less organized this morning. Satellite images show an asymmetric cloud pattern with the low-level center located near the northwestern edge of the main area of thunderstorms. This satellite presentation is indicative of moderate-to-strong northwesterly shear that is likely caused by the tropical cyclone's fast forward motion. The initial intensity is lowered to 65 kt following a blend of the latest Dvorak estimates. The hurricane passed by NOAA buoy 42059 a few hours ago, and the storm's minimum pressure was adjusted a few millibars higher based on the buoy's data. Another Air Force Hurricane Hunter aircraft will be flying through Elsa in a couple of hours, and the data the plane collects will provide a better estimate of Elsa's intensity and structure. Elsa continues to move very quickly to the west-northwest at about 27 kt. A subtropical ridge to the north of the hurricane should keep it on a west-northwest path, albeit at a slightly slower pace through the weekend. This should take the core of the storm just south of or over southern Hispaniola later today and near or across Jamaica and eastern Cuba on Sunday. Shortly after that time, Elsa is expected to near the western edge of the ridge and move toward a weakness over the southeastern U.S. In response to this pattern change, Elsa should slow down some more and turn to the north. The models appear to be slowly converging on a solution in showing the cyclone making the northward turn somewhere over Cuba on Monday and then heading in the vicinity of Florida or the eastern Gulf of Mexico late Monday through Wednesday. Although the models are in better agreement compared to previous days, there is still a considerable amount of spread in the GFS and ECMWF ensemble members, and the details of the long-term track are still uncertain. Some mid-level wind shear associated with Elsa's fast forward speed appears to be affecting the hurricane now. However, since the cyclone is expected to slow down and move beneath an upper-level anticyclone later this weekend, it seems likely that the vortex will become better aligned in the vertical. The big question is will Elsa be interacting with the mountainous islands of Hispaniola and Cuba when the environmental winds become conducive for strengthening. If the cyclone manages to stay south of those islands, Elsa could have an opportunity to restrengthen. Conversely, if the storm tracks directly over the islands, weakening would very likely occur. As a compromise, the NHC intensity forecast shows little change in strength through tonight, followed by slow weakening on Sunday and early Monday. Slight restrengthening is forecast when Elsa moves north of Cuba and across the eastern Gulf of Mexico. This forecast is a little lower than the previous one in the short term, but is largely unchanged at the longer forecast times. Given that there is still uncertainty in the track forecast and the degree of land interaction with Hispaniola and Cuba, users are urged to factor in some of this uncertainty. For reference, average NHC track errors at days 3 and 4 are 125 miles and 150 miles, respectively. The average NHC intensity errors are around 15 mph for both days 3 and 4. Key Messages: 1. Hurricane conditions and dangerous storm surge are expected within the Hurricane Warning areas in Haiti and the Dominican Republic later today and in Jamaica beginning Sunday. 2. Widespread heavy rain will move across southern Hispaniola and Jamaica today into Sunday where isolated to scattered flash flooding and mudslides will be possible. Heavy rain will then impact the Cayman Islands and Cuba Sunday into Monday resulting in significant flooding with mudslides in Cuba. As Elsa approaches the Florida Keys and southern Florida early next week, isolated flash flooding and minor river flooding will be possible. 3. Hurricane conditions and dangerous storm surge are possible in portions of eastern Cuba beginning early Sunday where a Hurricane Watch is in effect. There is an increasing risk of wind, storm surge, and rainfall impacts elsewhere in Cuba Sunday and Monday. 4. There is an increasing risk of storm surge, wind, and rainfall impacts beginning Monday in the Florida Keys and spreading northward along the Florida Peninsula through Tuesday. However, the forecast uncertainty remains larger than usual due to Elsa's potential interaction with the islands of Hispaniola and Cuba this weekend. Interests throughout Florida should monitor Elsa's progress and updates to the forecast. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 16.2N 69.0W 65 KT 75 MPH 12H 03/1800Z 17.5N 72.3W 65 KT 75 MPH 24H 04/0600Z 19.0N 75.4W 65 KT 75 MPH 36H 04/1800Z 20.5N 77.8W 60 KT 70 MPH 48H 05/0600Z 22.1N 79.7W 55 KT 65 MPH...INLAND 60H 05/1800Z 23.4N 81.2W 50 KT 60 MPH...OVER WATER 72H 06/0600Z 24.7N 82.2W 55 KT 65 MPH 96H 07/0600Z 28.2N 83.0W 55 KT 65 MPH 120H 08/0600Z 33.7N 80.2W 35 KT 40 MPH...INLAND $$ Forecaster Cangialosi/Berg
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