Tropical Cyclone Discussion
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000
WTPZ41 KNHC 290841
TCDEP1

TROPICAL STORM ANDRES DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP012015
300 AM MDT FRI MAY 29 2015

Andres`s intensification trend appears to have ceased for the
moment.  Infrared satellite imagery suggests that the cyclone is
trying to develop a banded-eye structure, but the overall pattern
really hasn`t improved much since the last advisory.  In fact, the
Dvorak final-T number from TAFB decreased to 3.5, and remained at
3.5 from SAB, so the initial intensity is being held at 60 kt.

The storm is moving a little slower to the west-northwest, or 295/8
kt, to the south of the subtropical ridge.  A slight weakness in the
ridge should allow Andres to move northwestward later today through
Saturday night.  The ridge is forecast to rebuild, however, and the
cyclone will likely move west-northwestward and then westward on
days 3-5.  There has been no apparent shift in the latest track
guidance as there had been in previous cycles, and therefore the
updated NHC track forecast is essentially unchanged from the
previous one.

The SHIPS model diagnostics indicate that a modest amount of north-
northeasterly shear is affecting Andres, which could be the reason
for the temporary hiatus in strengthening.  SHIPS indicates that
the current level of shear should continue for the next 24 hours,
and after that the thermodynamic environment becomes gradually less
favorable for significant strengthening.  Due to these less-than-
ideal conditions, the latest intensity guidance shows Andres peaking
at a lower intensity compared to previous cycles, and the updated
NHC intensity forecast has therefore been lowered a bit.  Even with
this adjustment, however, the official forecast is still higher
than most of the models, especially at 48 hours.

FORECAST POSITIONS AND MAX WINDS

INIT  29/0900Z 12.0N 113.9W   60 KT  70 MPH
 12H  29/1800Z 12.8N 114.8W   70 KT  80 MPH
 24H  30/0600Z 13.8N 115.7W   75 KT  85 MPH
 36H  30/1800Z 14.8N 116.6W   80 KT  90 MPH
 48H  31/0600Z 15.7N 117.5W   85 KT 100 MPH
 72H  01/0600Z 17.0N 120.0W   70 KT  80 MPH
 96H  02/0600Z 18.0N 123.0W   55 KT  65 MPH
120H  03/0600Z 18.5N 126.0W   40 KT  45 MPH

$$
Forecaster Berg




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