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Tropical Depression TWELVE-E


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TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP122014
200 AM PDT MON AUG 18 2014

The cloud pattern of the depression has not changed significantly
during the last several hours.  The cyclone has a large
circulation, with its associated wind field extending several
hundred miles across.  Curved banding is mainly confined to the
western half of the system due to about 15 kt of east-northeasterly
shear.  The latest Dvorak classifications continue to support an
initial wind speed estimate of 30 kt.   Some strengthening is
likely during the next few days while the cyclone remains over warm
water, within a moist air mass, and in an environment of moderate
shear.  The system is expected to move over cooler water and into a
more stable atmosphere by the end of the week, and that should
cause the cyclone to lose strength.  The weakening process over
cold water could be slower than normal as large cyclones like this
one typically take longer to spin down.

The depression is moving westward at about 8 kt on the south side
of a subtropical ridge.  This ridge is expected to shift eastward
and weaken while a trough deepens over California.  This pattern
change should cause the tropical cyclone to make a gradual turn
toward the north during the next 2 to 3 days.  Beyond that time, a
slight left turn is predicted as the trough lifts out.  The NHC
track forecast is a little to the left and slower than the previous
one to come into better agreement with the latest guidance.

It is worth noting that while the official forecast is well
offshore of the southwestern United States, model guidance does
show a surge of moisture partly associated with this system
extending into that region late Wednesday and Thursday.  Please
monitor products issued by your local National Weather Service
office for more details on a possible heavy rain threat.

FORECAST POSITIONS AND MAX WINDS

INIT  18/0900Z 16.0N 117.5W   30 KT  35 MPH
 12H  18/1800Z 16.4N 118.6W   35 KT  40 MPH
 24H  19/0600Z 17.0N 119.6W   45 KT  50 MPH
 36H  19/1800Z 17.7N 120.2W   50 KT  60 MPH
 48H  20/0600Z 18.4N 120.6W   50 KT  60 MPH
 72H  21/0600Z 19.7N 120.9W   50 KT  60 MPH
 96H  22/0600Z 22.2N 122.1W   45 KT  50 MPH
120H  23/0600Z 25.5N 124.5W   35 KT  40 MPH...POST-TROPICAL

$$
Forecaster Cangialosi

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