000
WTPZ44 KNHC 060242
TCDEP4
TROPICAL STORM MARIE DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP142008
800 PM PDT SUN OCT 05 2008
 
SUBJECTIVE DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB HAVE FALLEN
TO 2.0...OR 30 KT. HOWEVER...MARIE HAS BEEN MAINTAINING A SMALL
BURST OF DEEP CONVECTION PRIMARILY OVER THE WESTERN PART OF THE
CIRCULATION SINCE THE LAST ADVISORY...AND OBJECTIVE ADT ESTIMATES
FROM UW-CIMSS HAVE NOT FALLEN BELOW 35 KT. MARIE WILL BE KEPT AS A
35-KT TROPICAL STORM FOR NOW UNTIL THERE IS MORE CERTAINTY THAT IT
HAS INDEED WEAKENED TO A TROPICAL DEPRESSION. THE CYCLONE WILL
CONTINUE TO INGEST INCREASINGLY DRIER AND MORE STABLE AIR INTO ITS
CIRCULATION OVER THE NEXT FEW DAYS...AS INDICATED BY THE VARIOUS
SHIPS MODEL PARAMETERS...MAKING IT DIFFICULT FOR DEEP CONVECTION TO
PERSIST. THE OFFICIAL FORECAST CONTINUES TO WEAKEN MARIE TO A
DEPRESSION IN THE NEXT 12 HOURS THEN TO A REMNANT LOW BY 36
HOURS...IN LINE WITH THE SHIPS AND LGEM MODELS.
 
FIXES FROM AN 1812 UTC ASCAT PASS AND 2335 UTC TRMM PASS INDICATE
THAT MARIE HAS BEEN MOVING SLOWLY WEST-SOUTHWESTWARD OVER THE PAST
12 HOURS OR SO AT 250/3. AS MARIE SPINS DOWN...IT WILL CONTINUE TO
BE STEERED BY THE LOW-LEVEL TRADES IN A WEST-SOUTHWESTWARD
DIRECTION THROUGH 36 HOURS. THEREAFTER...ALMOST EVERY DYNAMICAL
MODEL INDICATES THAT THE REMNANT VORTICITY OF MARIE WILL BE DRAWN
IN SOME WAY BACK TO THE EAST TOWARDS THE EXPANDING CIRCULATION
ASSOCIATED WITH TROPICAL STORM NORBERT OFF THE COAST OF MEXICO.
HOWEVER...IT IS DOUBTFUL THAT A SURFACE LOW WILL REMAIN AT THAT
POINT...AND THE OFFICIAL FORECAST ASSUMES DISSIPATION WITHIN THE
ITCZ BY DAY 4. ALTHOUGH THE NEW FORECAST IS A LITTLE FARTHER SOUTH
THAN THE PREVIOUS FORECAST...IT STILL LIES ON THE NORTHWESTERN EDGE
OF THE GUIDANCE ENVELOPE.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0300Z 18.5N 123.0W    35 KT
 12HR VT     06/1200Z 18.4N 123.6W    30 KT
 24HR VT     07/0000Z 18.1N 124.5W    30 KT
 36HR VT     07/1200Z 17.7N 125.4W    25 KT...REMNANT LOW
 48HR VT     08/0000Z 17.2N 126.2W    25 KT...REMNANT LOW
 72HR VT     09/0000Z 16.0N 127.5W    20 KT...REMNANT LOW
 96HR VT     10/0000Z...DISSIPATED
 
$$
FORECASTER BERG/STEWART