|
Show Selection: |
| #378187 (Received by flhurricane at: 4:41 AM 23.Sep.2010) TCDAT4 TROPICAL DEPRESSION LISA DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL142010 500 AM AST THU SEP 23 2010 THE SATELLITE APPEARANCE OF LISA HAS CHANGED LITTLE DURING THE LAST SEVERAL HOURS. BURSTS OF DEEP CONVECTION CONTINUE TO FORM PRIMARILY NORTHEAST OF THE CIRCULATION CENTER BUT GENERALLY LACK MUCH ORGANIZATION. THE CLOUD SHIELD ASSOCIATED WITH LISA HAS ALSO BECOME MORE ASYMMETRIC DURING THE LAST 12 HOURS AND SEEMS PARTIALLY INVOLVED WITH A SHARP MID- TO UPPER-LEVEL TROUGH LOCATED NORTHEAST OF THE CYCLONE. DVORAK T-NUMBERS FROM SAB AND TAFB AT 0600 UTC HAVE DECREASED TO 1.5 AND 2.5...RESPECTIVELY. BASED UPON THESE ESTIMATES AND DATA FROM AN EARLIER ASCAT PASS...THE INITIAL INTENSITY IS LOWERED TO 30 KT. AS LISA ESCAPES THE INFLUENCE OF THE NEARBY MID-LATITUDE TROUGH DURING THE NEXT DAY OR TWO...THE STATISTICAL-DYNAMICAL GUIDANCE STILL INDICATES THE POTENTIAL FOR SOME MINOR RE-INTENSIFICATION. HOWEVER...WATERS ALONG THE FORECAST TRACK ARE MARGINALLY WARM...THE OCEANIC HEAT CONTENT IS NOT ESPECIALLY HIGH...AND THE CYCLONE SHOULD ENCOUNTER A SOMEWHAT STABLE ENVIRONMENT. BEYOND 48 HOURS...WESTERLY SHEAR ASSOCIATED WITH A NEW UPPER-LEVEL TROUGH DIGGING TO THE NORTHWEST OF LISA IS EXPECTED TO INCREASE SIGNIFICANTLY AND RESULT IN WEAKENING WHICH COULD OCCUR FASTER THAN CURRENTLY FORECAST. THE OFFICIAL NHC INTENSITY FORECAST IS LOWERED TO ACCOUNT FOR CURRENT TRENDS AND IS IN GOOD AGREEMENT WITH THE LATEST SHIPS/LGEM OUTPUT. LISA HAS CONTINUED MOVING EASTWARD IN A WEAK WESTERLY STEERING FLOW...AND THE INITIAL MOTION ESTIMATE IS 090/04. AS THE MID- TO UPPER-LEVEL TROUGH IMPARTING THIS MOTION LIFTS OUT DURING THE NEXT 12-24 HOURS...GLOBAL MODELS SHOW A LOW- TO MID-LEVEL RIDGE BUILDING NORTH OF LISA WHICH SHOULD LEAD TO A GRADUAL NORTHWESTWARD TURN WITH AN INCREASE IN FORWARD SPEED. THE TRACK GUIDANCE HAS BEEN IN REASONABLY GOOD AGREEMENT ON THIS SCENARIO...ALTHOUGH THE GFDL/ HWRF CONTINUE TO BE RIGHT OUTLIERS AS A RESULT OF WEAKER RIDGING. THE NEW NHC TRACK FORECAST IS A BASICALLY AN UPDATE OF THE PREVIOUS ONE AND IS LEFT OF THE MULTI-MODEL CONSENSUS...DOWNPLAYING THE CONTRIBUTION OF THE GFDL/HWRF. FORECAST POSITIONS AND MAX WINDS INITIAL 23/0900Z 17.7N 29.0W 30 KT 12HR VT 23/1800Z 18.1N 29.0W 30 KT 24HR VT 24/0600Z 18.5N 29.6W 35 KT 36HR VT 24/1800Z 19.1N 30.3W 40 KT 48HR VT 25/0600Z 20.0N 31.0W 40 KT 72HR VT 26/0600Z 21.5N 32.5W 40 KT 96HR VT 27/0600Z 23.5N 35.0W 35 KT 120HR VT 28/0600Z 26.0N 38.0W 25 KT...POST-TROP/REMNT LOW $$ FORECASTER KIMBERLAIN |
