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Tropical Depression TWELVE-E (Text)

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM

TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122014
200 PM PDT MON AUG 18 2014

The sprawling depression has been moving slowly west-northwestward
or 285/05 kt over the past 12 hours. The large cyclone is expected
to move slowly northwestward and then northward around the
southwestern periphery of a strong subtropical ridge during the next
72 hours or so. An unseasonably strong mid- to upper-level
trough dropping south-southeastward along the U.S. west coast,
which is expected to induce the northward motion by weakening the
ridge, is forecast by most of the NHC models to shift eastward into
the southwestern U.S. by Thursday. This will allow the ridge to
build back in to the north of the system, turning the cyclone back
to a northwesterly and west-northwesterly track after day 4. The new
forecast track is similar to the previous advisory track through 72
hours, but was shifted westward after that time closer to the
consensus model TVCE.

Subjective satellite intensity estimates from TAFB and SAB are a
consensus T2.0/30 kt. Some of the objective satellite analyses,
however, suggest that the cyclone could be a little higher.  The
sprawling nature of the depression and moderate easterly shear of
15-18 kt are expected to result in only slow strengthening for the
next 72 hours. After that time, the cyclone is forecast to move over
sub-26C SSTs, which should induce a slow weakening trend.  The
intensity forecast is just an update of the previous advisory and
closely follows the ICON consensus model.

A northward surge of moisture into the southwestern United States,
partly caused by the eastern portion of the depression's large
circulation, is still forecast by most of the global models to occur
by late Wednesday and Thursday.  Please monitor products issued by
your local National Weather Service office for more details on a
possible heavy rainfall threat.

FORECAST POSITIONS AND MAX WINDS

INIT  18/2100Z 16.6N 117.9W   30 KT  35 MPH
 12H  19/0600Z 17.0N 118.8W   35 KT  40 MPH
 24H  19/1800Z 17.6N 119.7W   40 KT  45 MPH
 36H  20/0600Z 18.2N 120.1W   45 KT  50 MPH
 48H  20/1800Z 18.9N 120.4W   50 KT  60 MPH
 72H  21/1800Z 20.6N 121.3W   50 KT  60 MPH
 96H  22/1800Z 23.0N 123.3W   40 KT  45 MPH
120H  23/1800Z 25.3N 125.8W   30 KT  35 MPH...POST-TROP/REMNT LOW

$$
Forecaster Stewart

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