Issued at 1100 AM AST Mon Sep 18 2023
000 WTNT45 KNHC 181443 TCDAT5 Hurricane Nigel Discussion Number 13 NWS National Hurricane Center Miami FL AL152023 1100 AM AST Mon Sep 18 2023 Nigel is exhibiting a somewhat ragged-looking eye on satellite imagery, surrounded by bands of very deep convection with cloud tops to -80 deg C. High-level outflow has become a bit restricted over the northeastern quadrant of the circulation, but overall the system continues to become better organized. The current intensity estimate of 70 kt is a blend of subjective and objective satellite-derived estimates. During the next day or so, the hurricane should remain in an environment that is quite conducive for strengthening. Vertical shear is forecast to remain very low and SSTs are near 28 deg C. The SHIPS Rapid Intensification (RI) Index continues to show above normal probabilities of RI. Accordingly, the official forecast calls for a 30-kt increase in intensity during the ensuing 24 hours. In a couple of days, increasing shear and cooler waters are likely to result in the beginning of a gradual weakening trend. In 4-5 days, global forecast models depict Nigel becoming involved with a frontal zone over the North Atlantic. Therefore, the official forecast shows the system as extratropical in 5 days, although this transition could occur a little sooner than that. Nigel's motion continues toward the northwest, or at about 325/10 kt. The hurricane is currently situated on the southwestern edge of a mid-level high pressure area. Over the next day or two, the system should move around the western periphery of the high. On this track, Nigel will turn northward in about 36 hours. Thereafter, the cyclone should accelerate in the flow to the southeast and south of a strong mid-latitude trough, and head into the higher latitudes of the Atlantic. The track guidance is fairly tightly clustered, and the new official forecast is very similar to the previous one. This is also in close agreement with the dynamical model consensus aids, HCCA and TVCA. FORECAST POSITIONS AND MAX WINDS INIT 18/1500Z 27.2N 51.4W 70 KT 80 MPH 12H 19/0000Z 28.4N 52.5W 85 KT 100 MPH 24H 19/1200Z 30.0N 53.9W 100 KT 115 MPH 36H 20/0000Z 32.0N 54.8W 100 KT 115 MPH 48H 20/1200Z 34.6N 54.5W 95 KT 110 MPH 60H 21/0000Z 37.4N 52.4W 90 KT 105 MPH 72H 21/1200Z 40.3N 47.7W 85 KT 100 MPH 96H 22/1200Z 46.5N 33.0W 70 KT 80 MPH 120H 23/1200Z 53.5N 20.0W 50 KT 60 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch
