Tropical Storm ANDRES

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TROPICAL STORM ANDRES DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022009
800 PM PDT SUN JUN 21 2009
 
VISIBLE AND INFRARED SATELLITE IMAGERY INDICATES THAT THE CYCLONE
HAS CONTINUED TO ORGANIZE DURING THE LAST 6 HOURS...WITH BANDING
FEATURES INCREASING AND A RECENT BURST OF CONVECTION OVER THE
CENTER IN WHAT APPEARS TO BE A DEVELOPING CENTRAL DENSE OVERCAST.
DVORAK T-NUMBERS AT 0000 UTC WERE 2.0 AND 2.5 FROM TAFB AND SAB.
THE INITIAL INTENSITY IS SET AT THE HIGHER ESTIMATE GIVEN THE
IMPROVEMENT IN THE SATELLITE PRESENTATION OF THE SYSTEM. THIS MARKS
THE LATEST FORMATION OF THE FIRST NAMED STORM IN THE EASTERN NORTH
PACIFIC BASIN SINCE 1971.
 
RECENT FIXES INDICATE AN INITIAL MOTION OF 275/05...WHICH IS TO THE
LEFT OF MOST OF THE GUIDANCE. THE MOST RECENT GFDL AND HWRF RUNS
IMMEDIATELY TAKE ANDRES ON A MORE NORTHERLY COURSE VERY CLOSE TO
THE SOUTHWESTERN COAST OF MEXICO DURING THE NEXT 24 TO 48 HOURS.
THESE TWO SOLUTIONS ARE WELL TO THE RIGHT OF THE REST OF THE MODEL
GUIDANCE...AND IT IS NOT CLEAR FROM MODEL FIELDS WHAT IS CAUSING
THIS MOTION. THE FORECAST WAS ADJUSTED ONLY SLIGHTLY TO THE RIGHT
OF THE PREVIOUS TRACK THROUGH 72 HOURS...BUT REMAINS LEFT OF THE
MODEL CONSENSUS. BY 72 HOURS...THE MODELS ARE IN BETTER AGREEMENT
THAT THE SUBTROPICAL RIDGE SHOULD GUIDE ANDRES ON A MORE
WEST-NORTHWESTERLY TRACK AWAY FROM THE COAST. ULTIMATELY...AS
ANDRES WEAKENS LATE IN THE PERIOD...THE CYCLONE WILL BE STEERED
WESTWARD WITH THE LOW-LEVEL FLOW.
 
SEA SURFACE TEMPERATURES REMAIN WARM ALONG THE FORECAST TRACK
THROUGH ABOUT 48-72 HOURS...WITH A FAIRLY RAPID DROP OFF IN OCEANIC
HEAT CONTENT THEREAFTER. HOWEVER...THE SHIPS MODEL INDICATES THAT
NORTHEASTERLY TO EASTERLY SHEAR WILL DEVELOP OVER THE CYCLONE DURING
THE NEXT COUPLE OF DAYS...AND NONE OF THE GUIDANCE SHOWS ANDRES
REACHING HURRICANE INTENSITY. THE OFFICIAL FORECAST HAS ANDRES
PEAKING IN INTENSITY IN A COUPLE OF DAYS...WITH A STEADY DECREASE
IN STRENGTH BEYOND 72 HOURS AS THE CYCLONE ENCOUNTERS INCREASINGLY
COOLER WATERS AND A MORE STABLE AIRMASS.
 
GIVEN THE FORECAST TRACK AND WIND RADII OF ANDRES...THE GOVERNMENT
OF MEXICO HAS ISSUED A TROPICAL STORM WATCH FOR A PORTION OF THE
SOUTHWESTERN COAST OF MEXICO.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 14.8N 101.9W    35 KT
 12HR VT     22/1200Z 15.1N 102.4W    40 KT
 24HR VT     23/0000Z 15.8N 103.2W    50 KT
 36HR VT     23/1200Z 16.6N 103.8W    55 KT
 48HR VT     24/0000Z 17.8N 104.8W    60 KT
 72HR VT     25/0000Z 20.5N 108.5W    50 KT
 96HR VT     26/0000Z 21.5N 113.0W    40 KT
120HR VT     27/0000Z 21.5N 117.5W    30 KT
 
$$
FORECASTER KIMBERLAIN
 
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