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Tropical Storm Humberto Forecast Discussion Number 11
2019-09-15 10:56:09| National Hurricane Center (Atlantic)
Issued at 500 AM EDT Sun Sep 15 2019 000 WTNT44 KNHC 150856 TCDAT4 Tropical Storm Humberto Discussion Number 11 NWS National Hurricane Center Miami FL AL092019 500 AM EDT Sun Sep 15 2019 Since reconnaissance aircraft departed the storm after midnight, the overall cloud pattern of Humberto has not changed appreciably. Both the earlier aircraft data and a blend of the most recent subjective satellite intensity estimates from SAB and TAFB still support an initial intensity of 50 kt. While there is significant banding evident over the northern and eastern portions of the circulation, the cyclone has not be able to maintain convection over the center, likely due to some mid-level dry air that has wrapped around the southwestern and southern part of the system. As Humberto moves slowly northward today, it will be over warm water and generally within low vertical wind shear. This should allow for strengthening, and the NHC foreast continues to calls for Humberto to become a hurricane later today or tonight. Additional strengthening is likely after that time when the storm recurves and remains within favorable environmental conditions. Late in the period, Humberto is forecast to interact with an approaching mid-latitude trough, and increasing shear ahead of that system is likely to cause weakening. This interaction should also begin Humberto's transition to an extratropical cyclone. The updated NHC intensity forecast is essentially unchanged from the previous advisory and is in best agreement with the HFIP corrected consensus model. Humberto continues to be steered north-northwestward at about 6 kt by a mid-level ridge over the western Atlantic. The tropical storm should turn northward and slow down later today as a weakness develops in the ridge. On Monday, a broad trough over the the northeastern United States is expected to turn Humberto northeastward, and then east-northeastward away from the United States. The dynamical models remain in good agreement on the overall track forecast scenario but there are some differences in the forward speed of Humberto after the east-northeastward turn. The latest NHC track is similar to, but a little slower than, the previous advisory. The new track forecast is closest to the multi-model consensus to account for the forward speed differences among the guidance. Large swells from Humberto will affect portions of the northwestern Bahamas and southeastern United States coast during the next few days. These swells are expected to produce dangerous surf conditions and life-threatening rip currents. See products issued by your local weather office for additional information. FORECAST POSITIONS AND MAX WINDS INIT 15/0900Z 28.3N 77.7W 50 KT 60 MPH 12H 15/1800Z 29.0N 77.9W 60 KT 70 MPH 24H 16/0600Z 29.6N 77.6W 65 KT 75 MPH 36H 16/1800Z 30.1N 76.7W 70 KT 80 MPH 48H 17/0600Z 30.5N 75.3W 75 KT 85 MPH 72H 18/0600Z 31.3N 71.2W 90 KT 105 MPH 96H 19/0600Z 33.5N 64.5W 95 KT 110 MPH 120H 20/0600Z 38.0N 58.0W 70 KT 80 MPH $$ Forecaster Brown
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