Tropical Storm KARINA

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TROPICAL STORM KARINA DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112014
800 AM PDT WED AUG 13 2014

Deep convection has continued to increase with cloud tops of -80C
to -84C noted just west of low-level center. Satellite intensity
estimates are a consensus T2.5/35 kt from TAFB, SAB, and UW-CIMSS
ADT. An earlier ASCAT overpass also indicated surface winds near
34 kt. Based on these data, the depression has been upgraded to
Tropical Storm Karina.

Karina is moving westward at 13 kt along the southwestern periphery
of a strong deep-layer subtropical ridge anchored over the
south-central and southwestern United States. The ridge is forecast
by the global models to build westward to the north and northwest
of the cyclone, which should keep Karina on a basic westward motion
throughout the 5-day period. The model guidance envelope has
shifted a little to the south with increasing spread, especially
beyond 72 hours. This is mainly due to the significant southward
shift by the ECMWF model, which shows a much weaker system being
steered more southwestward by moderate northeasterly trade wind
flow. The ECMWF model is considered to be an outlier at this time,
and the official track forecast is just a little faster than the
previous advisory and lies near the consensus model TCVE.

Karina is experiencing northeasterly vertical wind shear of 12-14
kt. Despite these modest shear conditions, the convective cloud
pattern of Karina has continued to develop into a classic hooked
band appearance, plus a small central dense overcast feature.
Microwave satellite data also suggests that the inner core wind
field has tightened somewhat up since the previous advisory. With
the wind shear currently affecting the system forecast to slowly
subside over the next 4 to 5 days while the cyclone is over 28-29C
SSTs, steady intensification appears likely. This development
scenario is consistent with the trend of all of the NHC model
guidance, and the NHC official intensity forecast indicates this by
making Karina a hurricane by 48 hours, which is higher than the ICON
intensity consensus model and closer to the SHIPS model.

FORECAST POSITIONS AND MAX WINDS

INIT  13/1500Z 17.2N 111.0W   35 KT  40 MPH
 12H  14/0000Z 17.4N 112.8W   45 KT  50 MPH
 24H  14/1200Z 17.5N 115.3W   55 KT  65 MPH
 36H  15/0000Z 17.6N 117.6W   60 KT  70 MPH
 48H  15/1200Z 17.8N 120.0W   65 KT  75 MPH
 72H  16/1200Z 18.3N 124.1W   75 KT  85 MPH
 96H  17/1200Z 18.5N 128.0W   75 KT  85 MPH
120H  18/1200Z 18.5N 131.1W   70 KT  80 MPH

$$
Forecaster Stewart

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