718 WTNT44 KNHC 162051 TCDAT4 Hurricane Humberto Discussion Number 17 NWS National Hurricane Center Miami FL AL092019 500 PM EDT Mon Sep 16 2019 A NOAA Hurricane Hunter aircraft investigating Humberto this afternoon found peak 850-mb flight-level winds of 78 kt in the western quadrant, along with SFMR surface winds of 71-72 kt, which is an increase in the winds in this part of storm since the earlier Air Force Reserve reconnaissance flight. The NOAA aircraft also measured a central pressure of 972 mb, down 4 mb from the previous flight. A combination of subjective and objective satellite intensity estimates of 90 kt and the aircraft data support an initial intensity of 80 kt. The initial motion estimate remains east-northeastward or 070/06 kt. Humberto made a wobble to the north during the past few hours, but has now wobbled toward the east, which is an indication that the hurricane's inner core is continuing to consolidate and contract. That being said, the latest model guidance is in even better agreement with and more convergent about the previous forecast track. Thus no significant changed were required through 72 hours. Thereafter, the models are also now in better agreement that Humberto will not slow down as much as previously expected, and the hurricane is forecast to gradually lift out and accelerate to the northeast on days 4 and 5 when Humberto is well to the northeast of Bermuda. No significant track changes were made to the previous advisory track through 48 hours, with the track having been nudged southward slightly on days 3-5 in agreement with the consensus models TVCN, NOAA-HCCA, and FSSE. Humberto has continued to strengthen at a rate of 20 kt per 24 hours, and I see no physical reasons why this trend should not continue for another 24-36 hours. By 48 hours and beyond, the hurricane will be entering the right-rear quadrant of a strong upper-level jet maximum that could briefly impart some additional baroclinic forcing on the cyclone, helping it to maintain its intensity or at least slow down the weakening process. By day 3 and beyond, however, the wind shear becomes prohibitively hostile at more than 50 kt, which should cause the central deep convection to erode, resulting in significant weakening. On day 5, extratropical transition over the colder north Atlantic waters is forecast to begin as Humberto interacts and possibly merges with a strong cold front. Large swells from Humberto will affect Bermuda by late Tuesday, and affect portions of the northwestern Bahamas and southeastern United States coast during the next couple of days. These swells are expected to produce dangerous surf conditions and life-threatening rip currents. See products issued by your local weather office and the Bermuda Weather Service for additional information. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 30.2N 75.9W 80 KT 90 MPH 12H 17/0600Z 30.4N 74.9W 90 KT 105 MPH 24H 17/1800Z 30.8N 73.3W 95 KT 110 MPH 36H 18/0600Z 31.2N 71.3W 100 KT 115 MPH 48H 18/1800Z 32.0N 68.7W 95 KT 110 MPH 72H 19/1800Z 36.0N 61.3W 85 KT 100 MPH 96H 20/1800Z 40.1N 59.0W 70 KT 80 MPH 120H 21/1800Z 41.7N 54.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart