000 WTPZ41 KNHC 292034 TCDEP1 TROPICAL STORM AGATHA DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP012010 200 PM PDT SAT MAY 29 2010 ALTHOUGH VISIBLE AND INFRARED SATELLITE IMAGERY INDICATE SOME EROSION OF THE CENTRAL CONVECTION...MICROWAVE IMAGERY INDICATES THAT BANDING FEATURES HAVE CONTINUED TO IMPROVE EAST AND SOUTH OF THE CENTER. THE INITIAL INTENSITY IS INCREASED TO 40 KT BASED ON A SATELLITE INTENSITY ESTIMATE OF 35 KT FROM BOTH TAFB AND SAB AND THE TIGHTER BANDING FEATURES NOTED IN MICROWAVE IMAGERY. THE INITIAL MOTION ESTIMATE IS 055/06 KT...WHICH MAY BE A LITTLE SLOW. AGATHA IS EXPECTED TO CONTINUE MOVING IN A NORTHEASTWARD OR EAST-NORTHEASTWARD DIRECTION FOR THE NEXT 24 HOURS AS THE CYCLONE MOVES AROUND THE WEST SIDE OF A BROAD MID-LEVEL RIDGE THAT LIES ALONG 12N LATITUDE. LANDFALL IS EXPECTED TO OCCUR ALONG THE GUATEMALAN COAST BY SUNDAY MORNING. AFTER LANDFALL...THE MOUNTAINOUS TERRAIN JUST INLAND FROM THE COAST IS EXPECTED TO CAUSE THE LOW-LEVEL CIRCULATION TO DECOUPLE FROM THE MID- TO UPPER-LEVEL CIRCULATION...WITH THE LATTER CONTINUING NORTHEASTWARD TOWARD THE YUCATAN PENINSULA OR THE NORTHWESTERN CARIBBEAN SEA. SIMILAR TO THE PREVIOUS ADVISORY...THE OFFICIAL TRACK IS CLOSE TO THE MODEL CONSENSUS...TVCN. THERE IS STILL SOME ROOM FOR SLIGHT ADDITIONAL STRENGTHENING BEFORE AGATHA MAKES LANDFALL...BUT THE WINDOW OF OPPORTUNITY IS QUICKLY CLOSING NOW DUE TO THE FASTER FORWARD SPEED. AFTER LANDFALL...RAPID WEAKENING OF THE SURFACE WINDS SHOULD OCCUR. HOWEVER...VERY MOIST SOUTHWESTERLY FLOW ON THE EAST SIDE OF AGATHA WILL CONTINUE TO SPREAD ACROSS MUCH OF GUATEMALA AND EL SALVADOR...WHICH WILL CONTINUE THE HEAVY RAINFALL THREAT EVEN AFTER THE SYSTEM CEASES TO EXIST AS A TROPICAL CYCLONE. DUE TO THE SLOW FORWARD SPEED AND INTERACTION WITH HIGH TERRAIN... THE MAIN IMPACT FROM AGATHA WILL BE EXTREMELY HEAVY RAINFALL. THESE RAINS COULD PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES OVER SOUTHEASTERN MEXICO...GUATEMALA...EL SALVADOR...AND AS FAR INLAND AS HONDURAS. FORECAST POSITIONS AND MAX WINDS INITIAL 29/2100Z 13.9N 92.4W 40 KT 12HR VT 30/0600Z 14.1N 91.9W 45 KT 24HR VT 30/1800Z 14.5N 91.2W 30 KT...INLAND 36HR VT 31/0600Z 14.9N 90.8W 25 KT...DISSIPATING INLAND 48HR VT 31/1800Z 15.2N 90.8W 20 KT...DISSIPATING INLAND 72HR VT 01/1800Z...DISSIPATED INLAND $$ FORECASTER STEWART/KIMBERLAIN