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Tropical Depression One Forecast Discussion Number 1
2020-05-16 22:39:25| National Hurricane Center (Atlantic)
Issued at 500 PM EDT Sat May 16 2020 000 WTNT41 KNHC 162039 TCDAT1 Tropical Depression One Discussion Number 1 NWS National Hurricane Center Miami FL AL012020 500 PM EDT Sat May 16 2020 Satellite images, Doppler radar data, and surface observations indicate that the low pressure system located just east of the coast of central Florida has developed sufficient organization to now be classified as a tropical depression. The low-level center is well defined and deep convection has persisted near the center and in bands on the east side of the circulation for the past several hours. The cyclone is considered tropical instead of subtropical because it has central deep convection and a relatively small radius of maximum wind. The initial intensity is estimated to be 30 kt based on data collected earlier today by the Air Force Hurricane Hunters. Another aircraft is scheduled to investigate the system this evening. Based on satellite data and the earlier reconnaissance fixes, the initial motion of the system is north-northeastward at 11 kt. A continued north-northeastward motion at about the same forward speed is expected during the next 24 hours or so, keeping the cyclone offshore, but parallel to, the east coast of Florida. After that time, the model solutions begin to diverge and the details of the track forecast become more complicated. The important features for the future track of the depression appear to be a pair of mid- to upper-level troughs currently over the central U.S. The specific amplitude, timing, and location of those troughs will ultimately result in how close to the coast of North Carolina this system gets. The GFS and HWRF models are on the left side of the guidance and bring the system inland or along the coast, while the ECMWF and UKMET models show an offshore track. The NHC track forecast splits the difference of these solutions, and lies close to the various consensus models, which usually perform best. It should be noted that forecast uncertainty is typically larger for weak systems like this one. The system should gradually strengthen during the next couple of days as it remains over the Gulf Stream current and in relatively low wind shear conditions. However, the surrounding air mass is not particularly moist, so that and the marginally warm SSTs should limit significant intensification. The NHC intensity forecast calls for the system to become a tropical storm tonight or on Sunday with continued slow strengthening as it nears the North Carolina coast. Extratropical transition should occur in about 3 days, or sooner. The NHC intensity forecast generally lies roughly near the middle of the guidance envelope. Key Messages: 1. A tropical storm watch has been issued for a portion of the North Carolina coast. Tropical-storm-force winds and heavy rains are possible there on Monday. 2. Dangerous coastal surf conditions and rip currents are expected to spread northward from Florida to the mid-Atlantic states during the next few days. See products from your local National Weather Service for more details. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 28.4N 78.6W 30 KT 35 MPH 12H 17/0600Z 29.7N 78.0W 35 KT 40 MPH 24H 17/1800Z 31.4N 77.4W 35 KT 40 MPH 36H 18/0600Z 33.0N 76.6W 40 KT 45 MPH 48H 18/1800Z 35.2N 74.8W 45 KT 50 MPH 60H 19/0600Z 37.1N 72.3W 50 KT 60 MPH 72H 19/1800Z 38.0N 70.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 20/1800Z 38.0N 68.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 120H 21/1800Z...DISSIPATED $$ Forecaster Cangialosi
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