Tropical Storm KARINA

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TROPICAL STORM KARINA DISCUSSION NUMBER  33
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112014
800 PM PDT WED AUG 20 2014

After looking fairly robust on the previous advisory, 25-30 kt of
vertical wind shear has left the convective cloud pattern looking
rather disheveled over the past several hours. A 20/2318 UTC AMSU
overpass indicated that the strong shear had displaced the
mid-level circulation at least 45 nmi southwest of the now fully
exposed low-level center. Satellite intensity estimates from both
TAFB and SAB have decreased, yielding an average intensity estimate
of 50 kt, which is the initial intensity used for this advisory.

As expected, the steering currents have collapsed and Karina has
been meandering in the same general area for the past 12 hours or
so. Little motion is expected tonight, with a drift to the east or
east-southeast forecast to begin on Thursday. After that, Karina is
expected to begin moving slowly northeastward as it comes under the
influence of the large circulation of Tropical Storm Lowell located
well to the east of the cyclone. As the distance between the two
systems decreases, smaller Karina is expected to accelerate
northeastward and then northward within the eastern portion of
Lowell's circulation, gradually getting drawn closer to the center
of Lowell.  NHC guidance remains in excellent agreement on this
developing track scenario, and the official forecast is similar to
but a little east of the consensus model TVCE in order to maintain a
reasonable physical distance between the centers of the two tropical
cyclones.

Fluctuations in the amount of Lowell-induced shear that will affect
Karina will also result in fluctuations in the cyclone's intensity
for the 72 hours while it remains over 26C and warmer SSTs. But
overall, no significant intensity changes are expected for the next
2 to 3 days. After that, however, increasing shear as Karina moves
closer to Lowell's center, plus sharply decreasing sea-surface
temperatures, will induce weakening on Days 4 and 5. Karina is
expected to become a post-tropical remnant low pressure system by 96
hours, but given the rather small size of the cyclone, it is
possible that the system could degenerate into an open trough as it
interacts with the larger circulation of Tropical Storm Lowell.

FORECAST POSITIONS AND MAX WINDS

INIT  21/0300Z 15.9N 136.4W   50 KT  60 MPH
 12H  21/1200Z 15.7N 136.3W   50 KT  60 MPH
 24H  22/0000Z 15.5N 135.8W   50 KT  60 MPH
 36H  22/1200Z 15.6N 135.1W   50 KT  60 MPH
 48H  23/0000Z 16.3N 134.1W   50 KT  60 MPH
 72H  24/0000Z 18.3N 131.0W   40 KT  45 MPH
 96H  25/0000Z 21.4N 128.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  26/0000Z 27.0N 129.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart

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