000 WTPZ42 KNHC 050834 TCDEP2 HURRICANE BLANCA DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL EP022015 300 AM MDT FRI JUN 05 2015 The convective structure of Blanca has improved during the past few hours, with an increase in the coverage of cold cloud tops around a ragged eye in geostationary imagery. The initial intensity is set to 90 kt based on a blend of the latest Dvorak estimates from TAFB and SAB (77 kt) and the latest UW-CIMSS ADT estimates of around 100 kt. An Air Force Reserve Hurricane Hunter aircraft is scheduled to investigate Blanca later today to provide more information on the intensity and structure of the cyclone. The initial 34-kt and 50-kt wind radii are based on data from ASCAT-A and ASCAT-B passes. The environment of low shear and warm SSTs should support some additional intensification during the next 24 hours or so. However, given the somewhat ragged appearance of the inner core on microwave imagery, only slight strengthening is shown in the official forecast, and even this is a bit above all of the guidance. By 36 hours the shear increases while the cyclone begins to move over cooler SSTs and into a drier airmass. This combination of factors should result in weakening, which should accelerate by 48 hours after Blanca crosses the 26C SST isotherm. The initial motion estimate is 320/09. Blanca is forecast to move generally northwestward to north-northwestward during the next several days, as it is steered by a ridge centered over northern Mexico and a trough west of the Baja California peninsula. There continues to be some spread in the guidance beyond 48 hours, likely due to differences in the extent of mid-level ridging north of Blanca. The ECMWF has trended a bit to the right this cycle but is still slower and west of the consensus, while the UKMET is even farther to the west. The GFS, GEFS mean, HWRF and GFDL continue to cluster farther right and faster. The new NHC track forecast is largely an update of the previous one through 48 hours and has been shifted a little to the right after that time. The official forecast is close to TVCE multi-model consensus through the period. Moisture associated with Blanca is moving northward and could help produce heavy rainfall over portions of southwestern Mexico during the next day or so, especially in areas of mountainous terrain. FORECAST POSITIONS AND MAX WINDS INIT 05/0900Z 14.3N 106.2W 90 KT 105 MPH 12H 05/1800Z 15.4N 107.2W 95 KT 110 MPH 24H 06/0600Z 16.9N 108.6W 95 KT 110 MPH 36H 06/1800Z 18.4N 109.5W 90 KT 105 MPH 48H 07/0600Z 20.0N 110.1W 75 KT 85 MPH 72H 08/0600Z 23.7N 111.1W 50 KT 60 MPH 96H 09/0600Z 26.5N 112.3W 35 KT 40 MPH...INLAND 120H 10/0600Z 28.0N 113.5W 20 KT 25 MPH...POST-TROP/INLAND $$ Forecaster Brennan