000
WTPZ42 KNHC 230241
TCDEP2
TROPICAL STORM ANDRES DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP022009
800 PM PDT MON JUN 22 2009
 
VISIBLE AND INFRARED SATELLITE IMAGERY INDICATES THAT ANDRES
CONTINUES TO SLOWLY BUT STEADILY DEVELOP...WITH THE CENTER EMBEDDED 
WITHIN A CENTRAL DENSE OVERCAST.  EARLIER TRMM AND AMSU-B PASSES
ALSO INDICATE WELL-DEFINED BANDING FEATURES AND THE POSSIBLE
FORMATION OF A PARTIAL EYEWALL.  0000 UTC T-NUMBERS FROM TAFB AND
SAB ARE BOTH 3.5 AND ARE USED TO SET THE INITIAL INTENSITY AT 55
KT.

THE BEST ESTIMATE OF THE INITIAL MOTION IS 315/7. WATER VAPOR IMAGES
AND CLOUD-TRACKED WINDS SHOW A LARGE AND STRONG SUBTROPICAL RIDGE
EXTENDING FROM THE CENTRAL U.S. SOUTHWESTWARD THROUGH NORTHERN
MEXICO...WITH A DEEP-LAYER TROUGH OFFSHORE THE CALIFORNIA COAST. 
ANDRES' CURRENT NORTHWESTWARD HEADING...FORECAST REASONABLY WELL BY
SEVERAL TRACK MODELS...APPEARS TO BE IN RESPONSE TO A WEAKNESS IN
THE SUBTROPICAL RIDGE OVER WESTERN MEXICO. HOWEVER...GLOBAL MODELS
SHOW THE RIDGE BUILDING WESTWARD OVER THE NEXT COUPLE OF
DAYS ...WHICH SHOULD STEER ANDRES MORE TOWARD THE WEST...BUT NOT
BEFORE IT NEARS THE SOUTHWESTERN COAST OF MEXICO ON TUESDAY. THE
OFFICIAL FORECAST IS SLOWER THAN THE MODEL CONSENSUS BUT SLIGHTLY
FASTER THAN THE PREVIOUS OFFICIAL FORECAST.

THE SHIPS MODEL CONTINUES TO SHOW NEARLY 20 KT OF NORTHEAST TO EAST
SHEAR OVER ANDRES AND MOST OF THE RELIABLE GLOBAL MODELS WEAKEN THE
CYCLONE IN ABOUT A DAY OR TWO. HOWEVER...GIVEN THE CURRENT UPWARD
INTENSITY TREND AND THE WARM SSTS ALONG ITS TRACK...A CONTINUED BUT
GRADUAL INTENSIFICATION THROUGH ABOUT 36 HOURS IS ANTICIPATED. 
ANDRES IS FORECAST TO REACH HURRICANE STRENGTH WITHIN 12 HOURS BUT
SHOULD REACH COOLER WATERS AND BEGIN INGESTING STABLE AIR IN ABOUT
36 HOURS...RESULTING IN A MORE RAPID DECREASE IN STRENGTH.  IT
SHOULD BE MENTIONED THAT...IF ANDRES MOVES TO THE RIGHT OF THE
FORECAST TRACK...IT COULD INTERACT MORE SIGNIFICANTLY WITH LAND AND
WEAKEN FASTER.  

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0300Z 16.8N 103.1W    55 KT
 12HR VT     23/1200Z 17.8N 104.0W    65 KT
 24HR VT     24/0000Z 19.2N 105.6W    65 KT
 36HR VT     24/1200Z 20.5N 107.0W    65 KT
 48HR VT     25/0000Z 21.0N 108.5W    55 KT
 72HR VT     26/0000Z 21.5N 111.0W    45 KT
 96HR VT     27/0000Z 22.0N 114.0W    35 KT
120HR VT     28/0000Z 22.0N 118.0W    25 KT...REMNANT LOW
 
$$
FORECASTER KIMBERLAIN/AVILA