000 WTPZ45 KNHC 122037 TCDEP5 Hurricane Darby Discussion Number 14 NWS National Hurricane Center Miami FL EP052022 1100 AM HST Tue Jul 12 2022 Darby remains a small and formidable hurricane, although there are some subtle changes in its convective pattern. The hurricane looks a little more asymmetric in infrared imagery, favoring the western side, and a black ring on the Dvorak enhancement curve (colder than -63 degrees Celsius) has struggled to stay wrapped around the eye. Subjective Dvorak Current Intensity numbers have gradually fallen closer to objective numbers, and the range of estimated intensities is now from 90-102 kt. Darby's current intensity is therefore lowered to 100 kt. Darby lost a little bit of latitude since overnight, but the 12-hour average motion remains westward, or 270/15 kt. The hurricane should maintain a westward motion for another 24 hours but then take on a slightly slower west-northwestward track from 36-48 hours as it moves toward a break in the subtropical ridge. After 48 hours, a filling of the break and a weaker Darby should cause the motion to turn back toward the west, continuing through dissipation in 4-5 days. There is very little spread among the track guidance, and the only noteworthy point is that the ECMWF and HCCA aid are faster than much of the other models. The updated NHC forecast is generally on top of the previous forecast but just a little faster during the first 36 hours, hedging toward the ECMWF and HCCA solutions. Vertical shear over Darby is expected to be 10 kt or less during the next 36 hours, but marginal sea surface temperatures of 26 degrees Celsius are likely to foster additional gradual weakening during that time. Southwesterly to westerly shear then increases in earnest to 20-30 kt on days 2 and 3, which should induce more significant weakening. The intensity guidance is in very good agreement, and Darby could weaken below hurricane strength soon after 48 hours, become post-tropical by day 4, and degenerate into a trough by day 5. Some of the global model guidance suggest that the post-tropical phase and dissipation could occur even sooner than indicated in the official forecast. FORECAST POSITIONS AND MAX WINDS INIT 12/2100Z 14.6N 131.2W 100 KT 115 MPH 12H 13/0600Z 14.8N 133.3W 95 KT 110 MPH 24H 13/1800Z 15.3N 136.0W 85 KT 100 MPH 36H 14/0600Z 16.0N 138.6W 75 KT 85 MPH 48H 14/1800Z 16.6N 141.0W 65 KT 75 MPH 60H 15/0600Z 17.0N 143.5W 55 KT 65 MPH 72H 15/1800Z 17.1N 146.3W 40 KT 45 MPH 96H 16/1800Z 17.0N 152.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 17/1800Z...DISSIPATED $$ Forecaster Berg