Tropical Storm LOWELL

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TROPICAL STORM LOWELL DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122014
800 PM PDT TUE AUG 19 2014

There has been little change in the organization of Lowell since
the last advisory, with multiple curved convective bands present
mainly in the southwestern semicircle.  Satellite intensity
estimates from TAFB and SAB remain 45 kt, and that is also the
initial intensity. The cirrus outflow is good to excellent in all
directions.

The initial motion is now 315/6.  Lowell is expected to move slowly
northwestward during the next 48 hours while a mid/upper-level
shortwave trough digs southward along the California coast and
weakens the subtropical ridge.  The trough should subsequently move
eastward allowing some ridging to rebuild to the north of the
storm. This is expected to cause Lowell to accelerate toward the
west-northwest by the end of the period.  The new forecast track is
an update of the previous forecast and lies near the center of the
guidance envelope.  It should be noted that Lowell and Karina are
likely to be close enough to interact by the end of the forecast
period.  At this time, it appears that the smaller Karina should
have only a minor impact on the track of the larger Lowell.

Lowell is expected to remain in a light/moderate vertical wind
shear environment for the next 4 days or so.  For the first 48
hours, the forecast track keeps the cyclone over sea surface
temperatures of 26C-27C.  After that, the temperatures along the
track are expected to decrease to near 22C by 120 hours.  Based
on these factors, the new intensity forecast is the same as the
previous advisory through 48 hours, then shows a slightly faster
weakening thereafter.  The latter part of the intensity forecast is
a little below the intensity consensus and is in best agreement
with the SHIPS and LGEM models.

FORECAST POSITIONS AND MAX WINDS

INIT  20/0300Z 18.7N 120.7W   45 KT  50 MPH
 12H  20/1200Z 19.1N 121.1W   50 KT  60 MPH
 24H  21/0000Z 19.6N 121.4W   50 KT  60 MPH
 36H  21/1200Z 20.5N 122.0W   50 KT  60 MPH
 48H  22/0000Z 21.5N 122.9W   50 KT  60 MPH
 72H  23/0000Z 24.0N 125.5W   40 KT  45 MPH
 96H  24/0000Z 26.0N 128.0W   30 KT  35 MPH
120H  25/0000Z 28.0N 131.0W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Beven

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