Tropical Depression FIFTEEN-E

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TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION FIFTEEN-E DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152007
200 AM PDT TUE OCT 16 2007
 
DEEP CONVECTION IS STILL NOT VERY WELL ORGANIZED...ALTHOUGH THERE IS
SOME SUGGESTION OF A BROKEN BAND OVER THE WESTERN SEMICIRCLE OF THE
CIRCULATION.  THE STRONGEST CONVECTIVE CLUSTER REMAINS SOMEWHAT
REMOVED FROM THE CENTER HOWEVER.  A QUIKSCAT PASS INDICATED THAT
THE MAXIMUM WINDS WERE JUST BELOW TROPICAL STORM STRENGTH...SO THE
ADVISORY INTENSITY IS HELD AT 30 KT.

AN SSM/I OVERPASS FROM A FEW HOURS AGO WAS HELPFUL IN ESTIMATING THE
CENTER POSITION.  ALTHOUGH THERE HAS BEEN A SLIGHT SOUTHWARD
DRIFT...THE INITIAL MOTION IS PRACTICALLY STATIONARY.  THE
DEPRESSION IS EMBEDDED WITHIN A BROAD LOW-LEVEL CYCLONIC GYRE WITH
VERY WEAK...OR NO...MID-TROPOSPHERIC STEERING.  THE GFS DOES BUILD
A WEAK MID-LEVEL RIDGE TO THE NORTH OF THE SYSTEM OVER THE NEXT
SEVERAL DAYS...BUT IT IS POSSIBLE THAT THE TROPICAL CYCLONE MAY NOT
BE ABLE TO ESCAPE FROM THE BROAD LOW-LEVEL CIRCULATION WITHIN WHICH
IT IS NOW EMBEDDED.  DYNAMICAL TRACK GUIDANCE REMAINS QUITE
DIVERSIFIED.  THE ECMWF AND U.K. MET. OFFICE MODELS TAKE THE SYSTEM
NEAR THE MEXICAN COAST IN 5 DAYS WHILE OTHER MODELS MOVE THE
TROPICAL CYCLONE NORTHWARD...NORTHWESTWARD...OR WESTWARD.  THE
OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE AND SHOWS A
SMALL LOOP DURING THE NEXT DAY OR TWO FOLLOWED BY A VERY SLOW
NORTHWESTWARD MOTION LATER IN THE PERIOD.  THIS IS ROUGHLY BETWEEN
THE GFDL AND GFS SOLUTIONS...ALBEIT NOT AS FAST.

AN EASTERLY SHEARING ENVIRONMENT CONTINUES TO PREVAIL OVER THE
TROPICAL CYCLONE...AND A MORE STABLE AIR MASS EXISTS NOT FAR TO THE
NORTHWEST.  THE SHIPS MODEL...USING THE GFS FORECAST FIELDS...
INDICATES THAT SIGNIFICANT EASTERLY SHEAR WILL PERSIST OVER THE
SYSTEM FOR THE NEXT SEVERAL DAYS.  ONLY SLIGHT STRENGTHENING IS
ANTICIPATED...SIMILAR TO WHAT WAS SHOWN IN THE PAST COUPLE OF
ADVISORY PACKAGES.  THIS IS IN FAIRLY CLOSE AGREEMENT WITH A
CONSENSUS OF THE SHIPS...GFDL...AND HWRF PREDICTIONS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 14.4N 108.9W    30 KT
 12HR VT     16/1800Z 14.3N 108.7W    35 KT
 24HR VT     17/0600Z 14.4N 108.4W    35 KT
 36HR VT     17/1800Z 14.6N 108.3W    35 KT
 48HR VT     18/0600Z 14.7N 108.5W    35 KT
 72HR VT     19/0600Z 15.0N 109.0W    35 KT
 96HR VT     20/0600Z 15.5N 109.5W    35 KT
120HR VT     21/0600Z 16.0N 110.0W    35 KT
 
$$
FORECASTER PASCH
 
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