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Tropical Depression Claudette Forecast Discussion Number 11
2021-06-20 10:48:28| National Hurricane Center (Atlantic)
Issued at 400 AM CDT Sun Jun 20 2021 000 WTNT43 KNHC 200848 TCDAT3 Tropical Depression Claudette Discussion Number 11 NWS National Hurricane Center Miami FL AL032021 400 AM CDT Sun Jun 20 2021 The area of deep convection near the center of Claudette has weakened over the past several hours, though rain bands have become more distinct in the southeastern quadrant. Surface observations continue to indicate that the maximum winds are about 25 kt, and these winds are almost all over the Gulf of Mexico well to the south of the center. Claudette is moving east-northeastward at about 11 kt. The system should gradually accelelerate in that direction through tonight as it moves ahead of a digging trough over the central United States, and all of the models show the system near the North Carolina coast by midday Monday. Claudette should then move even faster to the northeast through Tuesday ahead of the aforementioned trough due to stronger steering flow. Guidance remains in very good agreement through that time, and little change was made to the previous forecast. The end of the forecast remains uncertain as some of the guidance is showing more of a turn to the left closer to Nova Scotia. However, a stronger system would argue for something that remains more separate from the large mid-latitude trough steering the system, so the new forecast is close to the previous one, on the south side of the guidance. Conditions appear to be conducive for the re-development of Claudette once it encounters a more unstable marine environment late today. The system should move close to the Gulf Stream by Monday afternoon, likely fueling intensification while the shear is low. The previously divergent model suite is in better agreement now, with the GFS, UKMET and ECMWF models all showing the system becoming a tropical storm again near the North Carolina Outer Banks with some strengthening over the western Atlantic Ocean. Extratropical transiton should be quick after it moves north of the Gulf Stream, assisted by strong shear in 48 to 60 hours. The new intensity forecast is a little higher than the previous one, close to the NOAA Corrected Consensus Guidance. Key Messages: 1. Claudette is expected to produce heavy rainfall and flash flooding across portions of the Florida Panhandle, northern Alabama, and Georgia through this morning, and into the Carolinas through Monday morning. Considerable flash, urban, and small stream flooding impacts are possible across these areas. 2. Tropical storm conditions are expected along portions of the North Carolina coast late tonight and Monday, where a Tropical Storm Warning is in effect. Tropical storm conditions are possible in northeastern South Carolina tonight and Monday, where a Tropical Storm Watch is in effect. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 33.3N 85.8W 25 KT 30 MPH...INLAND 12H 20/1800Z 33.8N 83.2W 25 KT 30 MPH...INLAND 24H 21/0600Z 34.7N 79.1W 35 KT 40 MPH...INLAND 36H 21/1800Z 36.5N 74.5W 40 KT 45 MPH...OVER WATER 48H 22/0600Z 39.3N 69.5W 45 KT 50 MPH 60H 22/1800Z 42.7N 63.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 23/0600Z 46.5N 58.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 96H 24/0600Z...DISSIPATED $$ Forecaster Blake
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