ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Tropical Storm Rick Discussion Number 4 NWS National Hurricane Center Miami FL EP172021 400 AM CDT Sat Oct 23 2021 The satellite presentation of Rick has continued to improve overnight. The center is embedded within a fairly symmetric and expanding central dense overcast, and there is evidence of outer banding features. There has been no recent microwave imagery to examine the inner core structure, but given the recent satellite appearance and the earlier microwave data, it is likely that the inner core has become better defined. Subjective Dvorak T-numbers supported an intensity of 55 kt at 0600 UTC, and given the continued improvement in organization, the advisory intensity has been set at 60 kt. An Air Force Reserve reconnaissance aircraft is scheduled to investigate Rick this afternoon and should provide a better assessment of the storm's strength and structure. Rick has been intensifying quickly since it developed yesterday morning, and environmental conditions consisting of very low vertical wind shear, warm sea surface temperatures, and a moist low- to mid-level atmosphere are expected to continue to support rapid strengthening during the next day or so. The SHIPS rapid intensification index is showing a greater than 90 percent chance of rapid strengthening over the next 24 hours, and also indicates a better than 80 percent chance of a 45 kt increase in intensity over the next 36 hours. Based on this guidance the NHC intensity forecast calls for rapid strengthening during the next 24 to 36 hours, and the official forecast shows Rick reaching major hurricane status within 36 hours. This is near the higher end of the intensity guidance envelope, but is not as high as the HFIP corrected consensus aid. Increasing shear after that time and the possibility of an eyewall replacement cycle could cause some fluctuations in intensity before Rick reaches the coast of Mexico. After landfall, rapid weakening is expected, and Rick is likely to dissipate over the mountainous terrain of Mexico in 72 to 96 hours. Rick has turned north-northwestward or 330/5 kt. A slow north-northwestward to northward track is expected around the western side of a mid-level ridge centered of the Caribbean. Although the guidance agrees on that general steering flow, there are still significant difference regarding the location and timing of landfall in southern or southwestern Mexico. The GFS, Canadian, and HWRF are along the eastern edge of the track model envelope while the ECMWF, UKMET, and CTCI models are along the western side. The NHC track forecast has been adjusted slightly east of the previous advisory but remains close to the various consensus aids. It should be noted that the global model ensembles suggest a stronger cyclone is likely to track more eastward. Therefore the official forecast has been nudged in that direction and it is possible future eastward adjustments could be required. Based on the latest forecast, the government of Mexico has extended both the Hurricane and Tropical Storm Watches farther eastward. Hurricane and Tropical Storm Warnings will likely be required for portions of the watch areas later this morning. Key Messages: 1. Rick is expected to be at or near major hurricane strength when it reaches the coast of southern Mexico by Sunday night or Monday, and life-threatening storm surge and dangerous hurricane-force winds are possible within the Hurricane Watch area from Tecpan de Galeana to Punta San Telmo. There is larger-than-normal uncertainty in the track forecast of Rick, and the arrival time of hazardous conditions within the watch area could change significantly with future forecasts. Residents in this area should follow any advice given by local officials and check updates to the forecast. 2. Rick could bring tropical storm conditions to portions of the southern and southwestern coasts of Mexico as early as Sunday from east of Tecpan de Galeana to Acapulco, and by Monday morning from west of Punta San Telmo to Manzanillo, where a Tropical Storm Watch is in effect. 3. Heavy rains associated with Rick are expected to move into the Mexican states of Guerrero and Michoacan starting tonight, and could persist through Monday night. This rainfall will likely produce flash flooding and mudslides. FORECAST POSITIONS AND MAX WINDS INIT 23/0900Z 13.9N 101.4W 60 KT 70 MPH 12H 23/1800Z 14.6N 101.8W 75 KT 85 MPH 24H 24/0600Z 15.3N 102.1W 90 KT 105 MPH 36H 24/1800Z 16.0N 102.3W 100 KT 115 MPH 48H 25/0600Z 17.0N 102.7W 100 KT 115 MPH 60H 25/1800Z 18.5N 103.1W 80 KT 90 MPH...INLAND 72H 26/0600Z 20.5N 103.5W 30 KT 35 MPH...INLAND 96H 27/0600Z 25.0N 104.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 28/0600Z...DISSIPATED $$ Forecaster Brown NNNN