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Tropical Depression Emily Forecast Discussion Number 5
2017-08-01 04:43:49| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT Mon Jul 31 2017 000 WTNT41 KNHC 010243 TCDAT1 Tropical Depression Emily Discussion Number 5 NWS National Hurricane Center Miami FL AL062017 1100 PM EDT Mon Jul 31 2017 Mesonet observations from the area north and northwest of Lake Okeechobee indicate that Emily has an elongated surface circulation. Although some deep convection has redeveloped near and to the east of the center, Doppler velocity data from the Tampa and Melbourne WSR-88D radars only show winds of 30-35 kt at an elevation of about 5000 ft. Therefore, Emily's maximum sustained surface winds are estimated to be 25 kt, primarily within the thunderstorm activity east and southeast of the center. Emily's center, as seen on radar, has been moving east-southeastward for much of the evening. However, it seems to have recently turned eastward, and the initial motion estimate is 095/8 kt. Emily is embedded within the base of a mid-level trough that lies off the southeastern coast of the United States, and the subtropical ridge to the east should cause the cyclone to turn northeastward soon, move off the east-central Florida coast early Tuesday, and then accelerate over the western Atlantic during the next several days. Although all of the track models agree on this scenario, the GFS is a notable outlier compared to the other models, showing a slower solution that leans more to the left. Because the other models are so tightly clustered, the updated NHC track forecast leans closer to them and is a little bit faster than the previous forecast. There is low confidence in how strong Emily will get, or what exactly it will be, during the next few days. The global models keep Emily embedded within or near a weak frontal zone while it moves across the western Atlantic, suggesting that the cyclone's center may not move continuously but rather jump and reform from time to time along the boundary. These models also do not show Emily restrengthening much, even over the warm ocean, and phase-space diagrams suggest that the cyclone may become more cold core during the next few days. On the other hand, the more tropical models, like SHIPS and HWRF, show a little bit more re-intensification. Given that vertical shear is forecast to increase, and that Emily likely isn't purely tropical to begin with, the new NHC intensity forecast sides with the global models just a little bit more than SHIPS and HWRF. Based on this, Emily is forecast to intensify just a bit and become extratropical in about 48 hours. The extratropical low is expected to dissipate by day 5. The primary threat with Emily continues to be locally heavy rainfall across portions of the southern Florida peninsula and the Florida Keys overnight. FORECAST POSITIONS AND MAX WINDS INIT 01/0300Z 27.5N 81.0W 25 KT 30 MPH...INLAND OVER FLORIDA 12H 01/1200Z 28.7N 79.2W 30 KT 35 MPH...OVER WATER 24H 02/0000Z 30.4N 77.0W 30 KT 35 MPH 36H 02/1200Z 32.1N 74.6W 30 KT 35 MPH 48H 03/0000Z 33.7N 71.8W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 04/0000Z 36.6N 65.7W 35 KT 40 MPH...POST-TROP/EXTRATROP 96H 05/0000Z 38.5N 58.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 120H 06/0000Z...DISSIPATED $$ Forecaster Berg
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