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TROPICAL DEPRESSION ELEVEN-E DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2 PM PDT MON AUG 30 2004
 
VISIBLE AND INFRARED SATELLITE IMAGERY INDICATES THAT THE TROPICAL
DISTURBANCE SOUTHWEST OF ACAPULCO HAS BECOME ORGANIZED ENOUGH TO BE
CLASSIFIED AS A TROPICAL DEPRESSION. CURRENT SATELLITE INTENSITY
ESTIMATES REFLECT THIS WITH A CONSENSUS 2.0 FROM TAFB AND SAB. AFWA
CLASSIFIED THE SYSTEM WITH A 1.5 BASED ON THE PATTERN T...BUT THE
DATA T NUMBER WAS ALSO A 2.0. IN ADDITION...QUIKSCAT AMBIGUITY DATA
AND MICROWAVE IMAGERY PROVIDE ENOUGH SUPPORT FOR A SURFACE
CIRCULATION BOUNDED BY CONVECTION PRIMARILY OVER THE WESTERN
SEMICIRCLE. THE DEPRESSION BEGINS WITH AN INITIAL INTENSITY OF 30
KT.

INITIAL MOTION IS AN UNCERTAIN 300/6. THE DEPRESSION IS MOVING
SLOWLY TO THE WEST-NORTHWEST ON THE SOUTHERN PERIPHERY OF A WEAK
MID-LEVEL RIDGE WHICH EXTENDS ACROSS MEXICO AND IS ANCHORED BY AN
ANTICYCLONE OVER SOUTHERN CALIFORNIA. THIS GENERAL MOTION IS
EXPECTED OVER THE FIRST 48 HOURS BUT AN ACCELERATION IS ANTICIPATED
THEREAFTER AS THE SYSTEM BECOMES MORE UNDER THE INFLUENCE OF THE
RIDGE AND IS STEERED BY STRONGER DEEP-LAYERED FLOW. IN THE 4 TO 5
DAY RANGE...A LONGWAVE TROUGH IS EXPECTED TO MOVE ACROSS THE
WESTERN UNITED STATES. THIS MAY PROVIDE JUST ENOUGH WEAKNESS IN THE
RIDGE TO ALLOW FOR A SLOWER AND POTENTIALLY MORE NORTHWARD
MOTION...BUT THIS IS VERY RELIANT ON THE STRENGTH OF THE SYSTEM AT
THAT TIME. THE NOGAPS FAVORS A STRONG TROUGH AND THE UKMET FAVORS A
SHALLOW TROUGH. THE OFFICIAL FORECAST FOLLOWS THE GFS SOLUTION
WHICH IS A COMPROMISE OF THE NOGAPS AND UKMET.

THE OFFICIAL INTENSITY FORECAST GRADUALLY STRENGTHENS THE DEPRESSION
TO 60 KT BY 72 HOURS. THE SYSTEM WILL BEGIN MOVING OVER WATER
TEMPERATURES BELOW 26C AFTER 72 HOURS SO SLIGHT WEAKENING IS
ANTICIPATED THEREAFTER. VERTICAL SHEAR IS EXPECTED TO BE MARGINAL
THROUGH THE FORECAST PERIOD AND THIS SHOULD PLAY A CRITICAL PART IN
HOW STRONG THE SYSTEM WILL ULTIMATELY BECOME.
 
FORECASTER BERG/PASCH
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/2100Z 12.5N 103.9W    30 KT
 12HR VT     31/0600Z 13.0N 104.9W    35 KT
 24HR VT     31/1800Z 13.9N 106.8W    40 KT
 36HR VT     01/0600Z 14.8N 108.7W    45 KT
 48HR VT     01/1800Z 16.0N 111.0W    50 KT
 72HR VT     02/1800Z 18.5N 115.5W    60 KT
 96HR VT     03/1800Z 20.5N 119.5W    60 KT
120HR VT     04/1800Z 22.0N 123.0W    50 KT
 
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