ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM RRA Tropical Storm Adrian Discussion Number 1 NWS National Hurricane Center Miami FL EP012023 300 PM MDT Tue Jun 27 2023 The low pressure system located a few hundred miles off the southwestern coast of Mexico has quickly become better organized since last night, in terms of both its center definition and convective structure. ASCAT passes received a few hours ago indicated that the low has a well-defined center, and the system is already producing winds of around 40 kt. Based on this, advisories are being initiated on Adrian, the first tropical cyclone (and named storm) of the 2023 eastern Pacific season. With Adrian's center only recently forming, the initial motion is an uncertain 280/13 kt. A weakening subtropical ridge stretching across northern Mexico over the eastern Pacific is expected to steer Adrian generally westward during the next 3 days, but with its forward speed gradually decreasing during that time. The model guidance is in fairly good agreement during this period. There is significantly more uncertainty after day 3, and Adrian is expected to slow down further and turn toward the northwest and north due to (1) a developing mid- to upper-level low west of the Baja California peninsula and (2) possible interaction with another weather system to its east closer to the coast of Mexico. The NHC track forecast is close to the HCCA and TVCE consensus aids on days 4 and 5. Relatively low wind shear and warm sea surface temperatures of 28 to 29 degrees Celsius are likely to foster strengthening. In fact, some of the rapid intensification (RI) indices suggest that RI could occur, and the NHC forecast shows fast strengthening during the next couple of days. In general, the official intensity forecast is above the intensities of the hurricane regional models since they don't seem to be initializing the storm's structure very well. Model guidance suggests that moderate to strong easterly shear could develop over Adrian in about 3 days, with the storm also reaching cooler waters by around days 4 and 5. Therefore, weakening is indicated in the forecast toward the end of the forecast period. Adrian's genesis marks the second-latest formation of the first named storm during the eastern Pacific hurricane season, after Tropical Storm Agatha of 2016 which formed on July 2. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 15.3N 106.0W 40 KT 45 MPH 12H 28/0600Z 15.4N 107.4W 55 KT 65 MPH 24H 28/1800Z 15.4N 108.8W 65 KT 75 MPH 36H 29/0600Z 15.5N 110.3W 75 KT 85 MPH 48H 29/1800Z 15.6N 111.6W 75 KT 85 MPH 60H 30/0600Z 15.8N 112.7W 75 KT 85 MPH 72H 30/1800Z 16.0N 113.7W 70 KT 80 MPH 96H 01/1800Z 16.4N 115.1W 50 KT 60 MPH 120H 02/1800Z 17.3N 115.0W 35 KT 40 MPH $$ Forecaster Berg NNNN