000 WTNT43 KNHC 022052 TCDAT3 TROPICAL STORM LEE DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132011 400 PM CDT FRI SEP 02 2011 DATA FROM SATELLITES...SURFACE OBSERVATIONS...DOPPLER RADARS AND AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INDICATE TROPICAL STORM LEE HAS BECOME A LITTLE BETTER ORGANIZED DESPITE THE SIGNIFICANT WARMING OF CLOUD TOPS IN THE NORTHEAST QUADRANT OF THE CYCLONE. BUOY AND OIL RIG REPORTS OF 39-42 KT...ALONG WITH RELIABLE RECON SFMR WINDS OF 38-40 KT...JUSTIFY INCREASING THE INTENSITY TO 40 KT. THE INITIAL MOTION IS A SLOW DRIFT TO THE NORTH-NORTHWEST AT 2 KT. LEE REMAINS TRAPPED IN A HIGH AMPLITUDE BLOCKING PATTERN THAT IS FORECAST TO REMAIN INTACT FOR THE NEXT 24-36 HOURS AS A DEEP MID/UPPER-LEVEL TROUGH OFF THE SOUTHEAST U.S. COAST AMPLIFIES AND DIGS SOUTHWARD. BY 48 HOURS...THE NARROW RIDGE TO THE WEST OF LEE THAT EXTENDS FROM DEEP SOUTH TEXAS NORTHEASTWARD TO MISSOURI IS FORECAST BY ALL OF THE MODELS TO SLOWLY ERODE...WHICH SHOULD ALLOW THE CYCLONE TO GRADUALLY GAIN LATITUDE AND MOVE TOWARD LOUISIANA. A WEAK SHORTWAVE TROUGH FORECAST TO MOVE EASTWARD ACROSS THE SOUTHERN AND CENTRAL PLAINS BY 72 HOURS SHOULD INDUCE A FASTER...ALBEIT LESS THAN 10 KT...FORWARD MOTION TO THE NORTHEAST. BY DAY 4 OR 5...A WEAKENED LEE IS EXPECTED TO MERGE WITH A FRONTAL SYSTEM AND BECOME EXTRATROPICAL OVER THE LOWER TENNESSEE VALLEY. UNFORTUNATELY...THE SLOW FORWARD SPEED OF THE CYCLONE IS EXPECTED TO PRODUCE A HEAVY RAINFALL SCENARIO OVER LOUISIANA AND POINTS NORTHEASTWARD. THE FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK AND IS A BLEND OF THE GFS... UKMET...AND ECMWF MODEL TRACKS. WATER VAPOR IMAGERY INDICATES THAT LEE HAS BECOME ENTANGLED WITH A SMALL UPPER-LEVEL LOW. ALTHOUGH THIS CONFIGURATION SOMETIMES LEADS TO A RAPID SPIN UP OF THE LOW- AND MID-LEVEL VORTEX...VERY DRY MID-LEVEL AIR ASSOCIATED WITH THE LOW SHOULD CONTINUE TO BE ENTRAINED INTO THE SYSTEM. THIS UNFAVORABLE CONDITION IS EXPECTED TO INHIBIT THE DEVELOPMENT OF DEEP CONVECTION IN THE WESTERN SEMICIRCLE FOR THE NEXT 12-36 HOURS...DESPITE THE VERTICAL WIND SHEAR DECREASING TO LESS THAN 10 KT AND THE CYCLONE BEING OVER VERY WARM SSTS DURING THIS TIME. BY 48 HOURS...THE VERTICAL WIND SHEAR IS EXPECTED TO INCREASE FROM THE SOUTHWEST AHEAD OF A MID- TO UPPER-LEVEL TROUGH...WHICH SHOULD ACT TO CAP OFF THE STRENGTHENING PROCESS AS LEE ALSO MOVES OVER LAND. THE OFFICIAL FORECAST CALLS FOR ONLY MODEST STRENGTHENING UNTIL LANDFALL OCCURS...AND IS SIMILAR TO THE NHC INTENSITY CONSENSUS MODEL...ICON...WITH THE STATISTICAL MODELS ABOVE AND THE DYNAMICAL MODELS BELOW THE OFFICIAL FORECAST. FORECAST POSITIONS AND MAX WINDS INIT 02/2100Z 27.5N 91.5W 40 KT 45 MPH 12H 03/0600Z 27.9N 91.7W 45 KT 50 MPH 24H 03/1800Z 28.5N 91.7W 50 KT 60 MPH 36H 04/0600Z 29.2N 91.5W 55 KT 65 MPH 48H 04/1800Z 29.7N 91.1W 55 KT 65 MPH...INLAND 72H 05/1800Z 30.1N 89.9W 50 KT 60 MPH...INLAND 96H 06/1800Z 31.5N 88.2W 40 KT 45 MPH...INLAND 120H 07/1800Z 33.6N 86.7W 20 KT 25 MPH...POST-TROP/EXTRATROP $$ FORECASTER STEWART