000 WTPZ42 KNHC 221445 TCDEP2 TROPICAL STORM ANDRES DISCUSSION NUMBER 4 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP022009 800 AM PDT MON JUN 22 2009 A TRMM MICROWAVE PASS AT 1035 UTC SHOWED THAT THE CENTER OF ANDRES WAS LOCATED NORTHEAST OF THE EXPECTED POSITION. OVERALL...ANDRES APPEARS TO BE A LITTLE BETTER ORGANIZED...WITH VERY DEEP CONVECTION NEAR THE CENTER AND A MORE SYMMETRIC OUTFLOW AND CONVECTIVE PATTERN. THE INITIAL INTENSITY WILL BE HELD AT 45 KT IN ACCORDANCE WITH THE LATEST DVORAK ESTIMATES FROM TAFB/SAB. THE BEST ESTIMATE OF INITIAL MOTION IS 330/04...USING THE TRMM AND QUIKSCAT MICROWAVE FIXES FROM OVERNIGHT. WATER VAPOR IMAGES INDICATE THAT UPPER TROUGH OVER MEXICO IS JUST NORTH OF ANDRES AND THIS FEATURE MAY HAVE HELPED STEER THE SYSTEM MORE NORTHWARD THAN EXPECTED. HOWEVER...THE GLOBAL MODELS SHOW THIS TROUGH WEAKENING AND MOVING NORTHWARD WITH TIME AS RIDGING BUILDS OVER MEXICO. THE EXACT TIMING OF THESE EVENTS IS CRITICAL TO WHETHER ANDRES WILL MOVE NORTHWESTWARD NEAR THE COAST OF THE MEXICO FOR THE NEXT DAY OR TWO OR MOVE ONSHORE. THE OFFICIAL FORECAST HAS BEEN SHIFTED TO THE NORTHEAST AND NOW SHOWS THE CENTER OF ANDRES MOVING VERY CLOSE TO THE MEXICAN COAST. THE INTENSITY FORECAST THIS MORNING IS TRICKY WITH THE TRACK FORECAST EDGING CLOSER TO LAND. WHILE ANDRES REMAINS UNDER THE INFLUENCE OF WARM SSTS AND LIGHT TO MODERATE EASTERLY SHEAR... STRENGTHENING IS LIKELY. IN A DAY OR SO...THE PROXIMITY OF THE TROPICAL CYCLONE TO LAND MAY INHIBIT FURTHER INTENSIFICATION. IN A COUPLE OF DAYS...ANDRES WILL BEGIN TO FEEL THE EFFECTS OF COOLER SSTS SOUTH OF BAJA CALIFORNIA AND MORE STABLE AIR...CAUSING MORE SIGNIFICANT WEAKENING. MOST OF THE INTENSITY GUIDANCE DOES NOT SHOW AS MUCH STRENGTHENING AS BEFORE...PROBABLY BECAUSE OF THE INCREASING LIKELIHOOD OF SIGNIFICANT LAND INTERACTION. LITTLE CHANGE TO THE PREVIOUS NHC FORECAST IS SHOWN AT THIS TIME. HOWEVER...IF THE CENTER MOVES ANY FARTHER TO THE NORTHEAST...ANDRES COULD WEAKEN SIGNIFICANTLY MORE THAN FORECAST IN A COUPLE OF DAYS. ALTHOUGH THE OFFICIAL FORECAST TRACK DOES NOT EXPLICITLY INDICATE LANDFALL...IT IS CLOSE ENOUGH TO THE COAST THAT A TROPICAL STORM WARNING AND A HURRICANE WATCH ARE NOW REQUIRED FOR PORTIONS OF SOUTHWESTERN MEXICO. FORECAST POSITIONS AND MAX WINDS INITIAL 22/1500Z 16.0N 102.0W 45 KT 12HR VT 23/0000Z 16.7N 102.5W 55 KT 24HR VT 23/1200Z 17.8N 103.4W 60 KT 36HR VT 24/0000Z 19.0N 104.7W 65 KT 48HR VT 24/1200Z 20.0N 106.0W 60 KT 72HR VT 25/1200Z 21.5N 108.5W 50 KT 96HR VT 26/1200Z 22.0N 111.5W 40 KT 120HR VT 27/1200Z 22.0N 116.0W 25 KT...REMNANT LOW $$ FORECASTER BLAKE/BRENNAN