000 WTNT44 KNHC 160847 TCDAT4 Hurricane Humberto Discussion Number 15 NWS National Hurricane Center Miami FL AL092019 500 AM EDT Mon Sep 16 2019 The satellite presentation of the hurricane has continued to improve overnight, with the center embedded within a fairly symmetric area of cold cloud tops. Although no eye is evident in conventional satellite imagery, a ragged eye could be seen in long-range NWS Doppler radar data from Melbourne, Florida early in the night. Satellite intensity estimates from TAFB, SAB, and UW/CIMSS all support an intensity of 75 kt, and that is used as the initial wind speed for this advisory. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Humberto this morning, and should provide a better assessment of the storm's strength. Humberto is likely to continue intensifying during the next day or so while it moves over the warm waters of the Gulf stream and the shear is not expected to be prohibitive. The updated NHC forecast depicts a faster rate of strengthening over the first 36 hours than before, and is at the upper end of the guidance through that time. By 48 hours, increasing westerly shear should slow the intensification process, but baroclinic forcing caused by a mid-latitude trough is likely to help the cyclone remain strong until it begins its extratropical transition later in the period. Humberto is moving northeastward or 050/3 kt. The hurricane is forecast to move slowly east-northeastward during the next 24 hours, around the northwestern portion of a subtropical ridge. After that time, Humberto should continue on an east-northeastward heading, but at a slightly faster forward speed as a broad trough becomes established over the western Atlantic. Later in the period, a strong shortwave trough is forecast to dig southward which should cause Humberto to lift northeastward. The track guidance is in good agreement through 72 hours, and the confidence in that portion of the forecast is quite high. After that time, the forecast confidence decreases quite a bit as the model spread becomes unusually large. This is the due to differs in how Humberto interacts with the aforementioned trough. The GFS and HWRF shows Humberto getting caught by the trough as it cuts-off over the western Atlantic, while the ECMWF and UKMET show a more progressive solution, and take Humberto northeastward over the north Atlantic ahead of the trough. Given the model spread of more than 1000 n mi at day 5, the NHC track foreast remains close to the multi-model consensus, but confidence in the 4- and 5-day forecast is rather low. 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 16/0900Z 29.7N 77.3W 75 KT 85 MPH 12H 16/1800Z 30.0N 76.6W 85 KT 100 MPH 24H 17/0600Z 30.3N 75.4W 90 KT 105 MPH 36H 17/1800Z 30.6N 73.9W 95 KT 110 MPH 48H 18/0600Z 31.0N 72.0W 95 KT 110 MPH 72H 19/0600Z 33.0N 66.5W 95 KT 110 MPH 96H 20/0600Z 37.0N 62.0W 75 KT 85 MPH 120H 21/0600Z 40.0N 58.5W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown