ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Tropical Storm Carlotta Discussion Number 2 NWS National Hurricane Center Miami FL EP032024 200 PM MST Wed Jul 31 2024 The convective structure of the depression has continued to improve this afternoon, with plenty of curved bands on satellite imagery wrapping cyclonically around a well-defined center. After the prior advisory, a late arriving SSMIS pass also showed these cyclonic bands well on the 37-GHz channel. Subjective Dvorak intensity estimates were T3.0/45-kt from TAFB and T2.5/35-kt from SAB. Given the improvement in structure, the initial intensity is set at 40 kt this advisory, upgrading Tropical Depression Three-E to Tropical Storm Carlotta, the third named storm of the slow-starting 2024 East Pacific Hurricane Season. Carlotta has been moving a bit more poleward that previously expected, with the most recent 12-h motion averaging around 305/12-kt. This northwestward motion is soon expected to turn back more westward as it comes under the influence of a large deep-layer ridge centered over the southwestern United States. The global model guidance continues to advertise a broad weakness in this ridging forming on its western side by days 4-5, and a slowdown with some poleward turn is possible in Carlotta's track by the end of the forecast period. Overall, the guidance this cycle has shifted more northward than before, partially due to the initial position, but the NHC track forecast remains in good agreement with the consensus aids, in between the GFS and ECMWF solutions. The improvement in Carlotta's structure also could mean it is more poised to intensify faster than previously expected in the short-term. This possibility is reflected by the latest intensity guidance which is notably higher than before, showing Carlotta taking advantage of the favorable low vertical wind shear and warm sea-surface temperatures. In fact, the latest SHIPS rapid intensification (RI) index now indicates a 30-40 percent chance of RI over the next 24 hours. While the NHC intensity forecast will not quite show this rate of intensification yet, it is higher than before, and now peaks Carlotta as a 85-kt Category 2 hurricane in 60-72 hours. This intensity forecast is is pretty good agreement with the latest HFIP Corrected Consensus Approach (HCCA) forecast, but is now a shade under the latest HAFS-A/B forecast. Carlotta is still expect to begin moving over cooler waters by days 4-5 which should begin to induce a gradual weakening by the end of the forecast period. FORECAST POSITIONS AND MAX WINDS INIT 31/2100Z 16.2N 108.0W 40 KT 45 MPH 12H 01/0600Z 16.8N 109.8W 50 KT 60 MPH 24H 01/1800Z 17.3N 111.8W 60 KT 70 MPH 36H 02/0600Z 17.7N 113.9W 70 KT 80 MPH 48H 02/1800Z 17.8N 116.0W 80 KT 90 MPH 60H 03/0600Z 17.8N 118.2W 85 KT 100 MPH 72H 03/1800Z 17.8N 120.2W 85 KT 100 MPH 96H 04/1800Z 18.3N 122.2W 75 KT 85 MPH 120H 05/1800Z 19.3N 124.0W 65 KT 75 MPH $$ Forecaster Papin NNNN