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Tropical Depression FOUR-E


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TROPICAL DEPRESSION FOUR-E DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP042014
200 PM PDT SUN JUN 29 2014

Satellite images suggest that the depression's cloud pattern has not
become better organized since this morning.  Deep convection near
the center has decreased, while convection remains concentrated in a
long band over the western semicircle of the circulation. A partial
ASCAT overpass at 1722 UTC continues to indicate a large and
sprawling cyclonic envelope associated with the depression, with the
strongest winds well removed from the center of circulation. Dvorak
intensity estimates are a 2.5 and 2.0 from TAFB and SAB,
respectively, at 1800 UTC.  Given the lack of change in the system's
organization, the initial intensity estimate is maintained at 30 kt
for this advisory.

The center is still not obvious, even in visible satellite imagery,
and thus the initial motion estimate, or 295/14, is as uncertain as
it was previously. The cyclone should continue to move at a fast
clip on the south side of a strong subtropical ridge.  This ridge is
forecast to weaken and shift westward during the next couple of days
when a mid- to upper-level shortwave trough moves into the
California coast.  This should cause a notable reduction in the
forward speed of the cyclone during this time, with the track
becoming more westerly after that once the storm becomes more
shallow in nature.  The NHC track forecast remains on the left side
of the guidance envelope, slightly to the left of and slower than
the previous one through 36 hours.  The forecast track is adjusted
to the right and is slower beyond 36 hours but is not as far right
as the ECMWF, GFS, and multi-model consensus TVCE.

Low shear and warm waters along the depression's track should favor
intensification for another day or possibly two, but the large size
and slow evolution of inner core suggests that any strengthening
will only be gradual. Cooler waters and a drier and more stable
atmosphere should bring any intensification to a halt in about two
days, with slow but steady weakening after that time in the absence
of any significant shear.  The thermodynamics should become
increasingly unfavorable late in the forecast period, and remnant
low status is now forecast on day 5.  The NHC intensity forecast is
a bit lower than the previous one and close to the multi-model
consensus IVCN through 72 hours but a bit lower after that time.


FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z 16.5N 111.9W   30 KT  35 MPH
 12H  30/0600Z 17.0N 113.6W   35 KT  40 MPH
 24H  30/1800Z 17.6N 115.0W   45 KT  50 MPH
 36H  01/0600Z 18.3N 116.1W   50 KT  60 MPH
 48H  01/1800Z 18.7N 116.9W   50 KT  60 MPH
 72H  02/1800Z 18.8N 117.7W   40 KT  45 MPH
 96H  03/1800Z 18.9N 118.7W   30 KT  35 MPH
120H  04/1800Z 18.8N 120.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Kimberlain

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