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TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122015
800 AM PDT TUE AUG 25 2015

The depression is exhibiting a sheared cloud pattern, with an
asymmetric distribution of convection over the western semicircle
of the cyclone's circulation.  The cyclone's current appearance
makes sense, given that SHIPS model output and UW-CIMSS shear
analyses are indicating moderate southeasterly shear. Satellite
intensity estimates from TAFB and SAB are 2.0 and 2.5, respectively.
Although the depression's cloud pattern has become somewhat better
organized since late yesterday, the initial intensity is kept at 30
kt until there is more definitive proof that the system has reached
tropical storm strength.

The initial motion estimate is 270/05.  A deep longwave trough over
the eastern Pacific has temporarily weakened the subtropical ridge
west of 130W, which has left the cyclone in a weak easterly steering
flow. This synoptic pattern is expected to persist for the next
couple of days, which should maintain the slow westward motion. In
about 48 hours, the subtropical ridge is forecast to rebuild, which
should result in a west-northwestward track with an increase in
forward speed. The cyclone is forecast to maintain a 290- to
300-degree heading throughout the remainder of the forecast period.
The official forecast is very near the previous one, even though the
multi-model consensus has shifted toward the left. It has remained
about the same mostly because the GFS solution, which keeps the
cyclone very weak with a track far to the south, has largely been
discounted.

The shear currently affecting the depression is forecast to relax
in about 24 hours and remain low through about 3 days. The decrease
in shear, combined with anomalously warm waters of 28 to 29 deg C
and a moistening environment along the cyclone's path, suggest that
intensification is likely.  The one limiting factor could be how
long it takes for the inner core of the cyclone to become better
organized.  By early next week, the cyclone should encounter
westerly shear associated with the mid-oceanic trough anchored near
the longitude of Hawaii, and the shear should be strong enough to
result in a leveling off of the intensity and then weakening.
There is a significant difference between the statistical and
dynamical intensity guidance this cycle. The official intensity
forecast is above the previous one and close to, but a little lower
than, the stronger dynamical model guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 13.2N 132.4W   30 KT  35 MPH
 12H  26/0000Z 13.1N 133.3W   40 KT  45 MPH
 24H  26/1200Z 13.1N 134.6W   45 KT  50 MPH
 36H  27/0000Z 13.4N 136.1W   55 KT  65 MPH
 48H  27/1200Z 14.1N 138.1W   65 KT  75 MPH
 72H  28/1200Z 15.8N 141.8W   75 KT  85 MPH
 96H  29/1200Z 17.2N 145.1W   65 KT  75 MPH
120H  30/1200Z 18.7N 148.3W   60 KT  70 MPH

$$
Forecaster Kimberlain

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