000 WTPZ42 KNHC 050246 TCDEP2 HURRICANE BLANCA DISCUSSION NUMBER 18 NWS NATIONAL HURRICANE CENTER MIAMI FL EP022015 1000 PM CDT THU JUN 04 2015 The last available microwave data revealed that Blanca does not have much inner core convection, and a band of deep convection was closed off about 60 n mi from the center of circulation. A large eye is also noted in infrared satellite imagery, and it seems to have a sharper edge than six hours ago. A blend of Dvorak CI numbers from TAFB, SAB, and the UW-CIMSS ADT supports keeping the maximum winds at 85 kt for this advisory. Vertical shear remains low, as seen by expanding outflow in water vapor imagery, and sea surface temperatures ahead of the hurricane will be sufficiently warm for another 48 hours or so. The difficulty in the intensity forecast is that Blanca's structure could limit significant strengthening even with the favorable environment. The updated NHC intensity forecast allows for some modest strengthening during the next 24-36 hours. Fast weakening is expected after 48 hours due to increasing shear, cooler water, and a drier, more stable atmosphere, and Blanca is likely to weaken to a tropical storm while it approaches the southern Baja California peninsula. The official forecast is essentially a blend of the previous forecast and the intensity consensus (ICON). Blanca is accelerating toward the north-northwest, or 330/7 kt. The cyclone is expected to move northwestward or north-northwestward during the entire forecast period while moving between a mid-level trough west of the Baja California peninsula and high pressure over northern Mexico. There is some model disagreement after 72 hours, which appears to be related to the westward extension of the ridge in each model. For example, the GFS has a weaker ridge, allowing Blanca to move farther north and east than in the ECMWF. The updated NHC track forecast is very close to the previous forecast during the first 48 hours and then shifted slightly eastward from 72-120 hours. It has not been shifted as far to the east as the TVCE multi-model consensus, however. 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 05/0300Z 13.7N 105.7W 85 KT 100 MPH 12H 05/1200Z 14.7N 106.7W 85 KT 100 MPH 24H 06/0000Z 16.2N 108.1W 90 KT 105 MPH 36H 06/1200Z 17.7N 109.2W 90 KT 105 MPH 48H 07/0000Z 19.2N 109.9W 80 KT 90 MPH 72H 08/0000Z 22.5N 110.9W 55 KT 65 MPH 96H 09/0000Z 25.7N 112.1W 35 KT 40 MPH 120H 10/0000Z 27.9N 113.4W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg