000
WTPZ41 KNHC 310836
TCDEP1
TROPICAL DEPRESSION ALVIN DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP012007
200 AM PDT THU MAY 31 2007
 
TENACIOUS ALVIN CONTINUES TO GENERATE INTERMITTENT BURSTS OF DEEP
CONVECTION...ALTHOUGH THE OVERALL COVERAGE AND INTENSITY APPEARS TO
DECREASE WITH EACH NEW ROUND.  INDEED...ALVIN IS BARELY HANGING ON
TO TROPICAL CYCLONE STATUS AND ANY FURTHER REDUCTION IN CONVECTION
WOULD RESULT IN IT DEGENERATING INTO A REMNANT LOW.  THE INITIAL
INTENSITY IS GENEROUSLY SET AT 30 KT BASED ON AN EARLIER QUIKSCAT
PASS.  SINCE ALVIN IS EXPECTED TO REMAIN IN AN UNFAVORABLE
ENVIRONMENT...SLOW WEAKENING IS EXPECTED AND ALVIN SHOULD BECOME A
REMNANT LOW IN A DAY OR TWO...IF NOT SOONER.
 
ALVIN APPEARS TO HAVE TURNED A LITTLE MORE TOWARDS THE WEST-
SOUTHWEST AND THE INITIAL MOTION ESTIMATE IS NOW 250/4.  MODEL
GUIDANCE IS TRENDING MORE TOWARDS THE SOUTH WITH A COUPLE OF THE
DYNAMICAL MODELS INDICATING THAT ALVIN WILL TURN DUE SOUTH OR EVEN
SOUTHEAST AS IT GETS CAUGHT IN THE LOW-LEVEL WESTERLY FLOW
ASSOCIATED WITH THE ITCZ.  WHILE THIS SOLUTION IS CERTAINLY
PLAUSIBLE...IT WOULD REQUIRE THAT ALVIN BECOME A SHALLOW CYCLONE
IMMEDIATELY.  GIVEN ALVIN'S PAST ABILITY TO CONTINUOUSLY GENERATE
NEW BURSTS OF CONVECTION DESPITE A SEEMINGLY HOSTILE ENVIRONMENT...
I'M NOT READY TO BITE OFF ON SUCH A DRASTIC CHANGE IN THE TRACK
REASONING.  STILL...CURRENT TRENDS IN SATELLITE IMAGERY SEEM TO
INDICATE THAT ALVIN WILL BECOME A SHALLOW SYSTEM SOONER RATHER THAN
LATER THUS NECESSITATING A SOUTHWARD SHIFT IN THE OFFICIAL FORECAST
TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/0900Z 12.9N 115.5W    30 KT
 12HR VT     31/1800Z 12.9N 116.0W    30 KT
 24HR VT     01/0600Z 12.7N 116.8W    25 KT
 36HR VT     01/1800Z 12.6N 117.4W    25 KT
 48HR VT     02/0600Z 12.4N 118.0W    25 KT...REMNANT LOW
 72HR VT     03/0600Z 12.0N 119.0W    20 KT...REMNANT LOW
 96HR VT     04/0600Z 11.0N 120.5W    20 KT...REMNANT LOW
120HR VT     05/0600Z 10.0N 122.0W    20 KT...REMNANT LOW
 
$$
FORECASTER RHOME