Issued at 500 AM AST Mon Sep 18 2023
000 WTNT45 KNHC 180844 TCDAT5 Hurricane Nigel Discussion Number 12 NWS National Hurricane Center Miami FL AL152023 500 AM AST Mon Sep 18 2023 Infrared satellite imagery indicates that Nigel is getting better organized in a hurry. Deep convective towers have been quickly rotating around a developing eyewall, and an AMSR2 microwave pass indicated that a low-level eye feature had developed. Intensity estimates at 06 UTC ranged from 60-70 kt, and given the increasing organization on satellite and microwave data, the initial wind speed is raised to 70 kt. It seems like the long-awaited rapid intensification phase of Nigel is underway. Very deep convective cloud tops are in the central dense overcast, with warm waters and light shear for at least a day or two along the path of the hurricane. These conditions should promote significant strengthening, and it makes sense to forecast a period of rapid intensification, only moderated by somewhat cooler waters after 36 hours, along with possible eyewall replacement cycles. It is interesting to note that most of the regional hurricane guidance has come down this cycle, with the hurricane models showing a very deep, but larger system with lower maximum winds. The new forecast is closer to the previous NHC interpolated forecast, the statistical aids, and the COAMPS-TC ensemble. Nigel should undergo a quick extratropical transition between days 4 and 5, consistent with all of the global model predictions. Nigel is moving northwestward with an estimated motion of 325/10 kt. This general northwestward to north-northwestward heading should continue for the next couple of days as a mid-level ridge builds to the northeast of the system. In a couple of days, Nigel will reach the western edge of the ridge and turn more northward. By the end of the forecast period, a strong trough will pick up the system, and Nigel should accelerate quite rapidly towards the northeast. There are no significant changes to report with the latest NHC track forecast, as at last the rightward shift of the guidance seems to have ended. FORECAST POSITIONS AND MAX WINDS INIT 18/0900Z 26.5N 50.7W 70 KT 80 MPH 12H 18/1800Z 27.6N 51.8W 85 KT 100 MPH 24H 19/0600Z 29.1N 53.3W 100 KT 115 MPH 36H 19/1800Z 30.8N 54.6W 105 KT 120 MPH 48H 20/0600Z 33.1N 55.0W 100 KT 115 MPH 60H 20/1800Z 35.7N 53.9W 95 KT 110 MPH 72H 21/0600Z 38.5N 50.8W 90 KT 105 MPH 96H 22/0600Z 44.5N 37.3W 70 KT 80 MPH 120H 23/0600Z 51.5N 21.5W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Blake
