Tropical Depression ALVIN

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM
TROPICAL DEPRESSION ALVIN DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
800 AM PDT WED MAY 30 2007
 
CONVECTION HAS FLARED NEAR ALVIN THIS MORNING...WITH THE CENTER ON
THE NORTHEASTERN PORTION OF A BAND. SATELLITE CLASSIFICATIONS ARE
ABOUT THE SAME AS EARLIER...AND THE INITIAL INTENSITY WILL BE HELD
AT 30 KT. NO SIGNIFICANT CHANGE IN STRENGTH IS EXPECTED FOR THE
NEAR TERM. THIS IS BASICALLY A PERSISTENCE FORECAST SINCE ALVIN HAS
BEEN PRETTY WEAK ITS ENTIRE LIFETIME IN ABOUT THE SAME ENVIRONMENT.
HOWEVER THE GFS INDICATES THAT UPPER DIVERGENCE WILL DECREASE NEAR
THE DEPRESSION BY ABOUT TWENTY-FOUR HOURS...WHICH COULD LIMIT THESE
PERIODIC BURSTS OF CONVECTION THAT ALVIN HAS BEEN PRODUCING FOR
DAYS. THUS THE INTENSITY FORECAST WILL BE REDUCED FROM THE PREVIOUS
FORECAST...BUT IS STILL A LITTLE HIGHER THAN THE GFDL/SHIPS
GUIDANCE. UPPER CONDITIONS LOOK EVEN LESS FAVORABLE FOR DEVELOPMENT
IN THE LONG TERM...AND ALVIN SHOULD BECOME A REMNANT LOW IN FOUR
DAYS OR SO...IF NOT SOONER.

A PAIR OF MICROWAVE PASSES NEAR 0900 UTC SUGGEST THAT ALVIN HAS BEEN
MOVING A LITTLE SLOWER AND TO RIGHT OF ITS PREVIOUS TRACK...GIVING
A LONG-TERM MOTION OF 300/3. RIDGING IS FORECAST TO BUILD TO THE
NORTH OF THE DEPRESSION...WHICH SHOULD FORCE A WESTWARD MOTION IN A
DAY OR SO. THEREAFTER...RIDGING IN THE LOW TO MID-LEVELS IS
ORIENTED FROM EAST-NORTHEAST TO WEST-SOUTHWEST. ALL GLOBAL MODELS
RESPOND BY SENDING THE CYCLONE ON A WEST-SOUTHWEST OR SOUTHWEST
TRACK. THE OFFICIAL FORECAST IS A LITTLE NORTH OF THE PREVIOUS
ADVISORY INITIALLY AND A LITTLE SLOWER THAN THE DYNAMICAL MODEL
CONSENSUS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      30/1500Z 13.4N 114.6W    30 KT
 12HR VT     31/0000Z 13.6N 115.1W    30 KT
 24HR VT     31/1200Z 13.7N 116.1W    25 KT
 36HR VT     01/0000Z 13.7N 117.1W    25 KT
 48HR VT     01/1200Z 13.4N 118.1W    25 KT
 72HR VT     02/1200Z 12.8N 119.4W    25 KT
 96HR VT     03/1200Z 12.0N 120.7W    20 KT...REMNANT LOW
120HR VT     04/1200Z 11.0N 122.3W    20 KT...REMNANT LOW
 
$$
FORECASTER BLAKE
 
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