#380 Postby cycloneye » Thu Jun 04, 2015 9:47 pm
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
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