000 WTPZ45 KNHC 101445 TCDEP5 Tropical Storm Darby Discussion Number 4 NWS National Hurricane Center Miami FL EP052022 500 AM HST Sun Jul 10 2022 Darby has become better organized this morning. A 0916 UTC AMSR2 and more recent 1216 UTC SSMIS microwave pass have revealed increased banding over the eastern semicircle of the storm and an improved low-level inner core structure. Early-light visible satellite imagery also shows an increase in banding and the development of a small CDO feature. Subjective Dvorak intensity estimates have responded accordingly and are now up to 45 and 55 kt from TAFB and SAB, respectively. Therefore, the initial intensity has been raised to 50 kt for this advisory. There still appears to be some entrainment of drier mid-level air over the northwestern portion of the circulation, but with low environmental shear and warm sea-surface temperatures (SSTs) ahead, Darby should be able to strengthen over the next 36-48 hours. The updated NHC intensity forecast shows a faster rate of strengthening during the first day or so, primarily due to the higher initial intensity. The new forecast calls for Darby to become a hurricane in about 24 hours, and then peak in intensity in a couple of days. After that time, gradually decreasing SSTs and a more stable environment should lead to steady weakening during the remainder of the forecast period. The NHC wind speed forecast is near the high end of the guidance during the first 24-48 hours and is in best agreement with the European-based SHIPS model. Thereafter, it is close to the various consensus aids. Darby continues to move westward at about 13 kt. The cyclone should continue on a westward motion to the south of a mid-level ridge extending westward from the northern portion of Baja California. In a few days the western portion of the ridge is forecast to weaken which should cause Darby to turn west-northwestward. The track guidance is in general agreement on this scenario, though the UKMET model depicts a much weaker Darby and shows a faster westward motion. The NHC forecast is closest to the ECMWF, which is a little slower than the consensus aids due to the contribution from the much faster UKMET model. FORECAST POSITIONS AND MAX WINDS INIT 10/1500Z 14.3N 117.6W 50 KT 60 MPH 12H 11/0000Z 14.3N 119.6W 60 KT 70 MPH 24H 11/1200Z 14.3N 122.2W 70 KT 80 MPH 36H 12/0000Z 14.4N 124.6W 75 KT 85 MPH 48H 12/1200Z 14.8N 127.1W 80 KT 90 MPH 60H 13/0000Z 15.2N 129.5W 75 KT 85 MPH 72H 13/1200Z 15.8N 131.9W 65 KT 75 MPH 96H 14/1200Z 17.3N 136.7W 50 KT 60 MPH 120H 15/1200Z 18.2N 141.5W 35 KT 40 MPH $$ Forecaster Brown