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
 

WTNT43 KNHC 030257
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 PM CDT FRI SEP 02 2011
 
SATALLITE...SURFACE...AND RECONNAISSANCE AIRCRAFT DATA INDICATE THAT
LEE HAS BEEN MOVING SLOWLY NORTHWARD THIS EVENING.  THE CENTER IS
LOCATED TO THE SOUTHWEST OF A BURST OF DEEP CONVECTION THAT
DEVELOPED LATE THIS AFTERNOON AND HAS BEEN EXPANDING IN SIZE THIS
EVENING.  WIND REPORTS FROM BUOYS AND OIL RIGS OVER THE GULF AND
DATA FROM THE AIRCRAFT INDICATE THAT INTENSITY OF THE TROPICAL
STORM REMAINS AROUND 40 KT.
 
LEE IS CURRENTLY LOCATED TO THE SOUTHWEST OF A MID-LEVEL RIDGE THAT
IS CENTERED OVER THE OHIO VALLEY.  THIS RIDGE IS FORECAST TO WEAKEN
AND SLIDE EASTWARD DURING THE NEXT DAY OR SO...AS A MID-LATITUDE
TROUGH MOVES INTO THE NORTH-CENTRAL UNITED STATES.  THIS SHOULD
ALLOW LEE TO MOVE SLOWLY NORTHWARD DURING THE NEXT 24-36 HOURS. AS
THE TROUGH PASSES NORTH OF THE TROPICAL STORM IN 36-48 HOURS...THE
MODELS SUGGEST THAT LEE WILL SLOW DOWN AND MEANDER NEAR OR OVER
SOUTHERN LOUISIANA.  AFTER THAT TIME...THE TROUGH IS FORECAST TO
INTERACT WITH THE CYCLONE AND LEE SHOULD MOVE NORTHEASTWARD AT A
FASTER FORWARD SPEED AND BECOME EXTRATROPICAL LATE IN THE PERIOD. 
THE MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH THIS SCENARIO...
HOWEVER THERE ARE SOME LARGE DIFFERENCE IN THE FORWARD SPEED OF LEE
ESPECIALLY AFTER 48 HOURS.  THE NEW OFFICIAL FORECAST IS A BLEND OF
THE GFS AND ECMWF MODELS AND IS A LITTLE FASTER THAN THE PREVIOUS
ADVISORY...MAINLY DUE TO THE MORE NORTHWARD INITIAL POSITION.  IT
IS IMPORTANT NOT TO FOCUS ON THE EXACT TRACK OF LEE...SINCE
TROPICAL STORM CONDITIONS AND HEAVY RAINFALL EXTEND WELL AWAY OF
THE CENTER.
 
A SMALL UPPER-LEVEL LOW TO THE NORTHWEST OF LEE CONTINUES TO 
IMPART ABOUT 15-20 KT OF SOUTHWESTERLY SHEAR OVER THE TROPICAL
CYCLONE.  THIS UPPER-LOW IS FORECAST TO WEAKEN DURING THE NEXT
12-24 HOURS...WHICH SHOULD PROVIDE A MORE FAVORABLE UPPER AIR
ENVIRONMENT AND ALLOW FOR GRADUAL STRENGTHENING.  THE NHC INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY THROUGH LANDFALL AND
IS IN GOOD AGREEMENT WITH THE SHIPS/LGEM GUIDANCE.    
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0300Z 28.2N  91.6W   40 KT  45 MPH
 12H  03/1200Z 28.6N  91.6W   50 KT  60 MPH
 24H  04/0000Z 29.4N  91.5W   55 KT  65 MPH
 36H  04/1200Z 30.0N  91.3W   50 KT  60 MPH...INLAND
 48H  05/0000Z 30.2N  91.0W   45 KT  50 MPH...INLAND
 72H  06/0000Z 31.5N  89.0W   40 KT  45 MPH...INLAND
 96H  07/0000Z 34.0N  87.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  08/0000Z 35.5N  86.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BROWN
 

WTNT43 KNHC 030857
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
400 AM CDT SAT SEP 03 2011

SURFACE AND AIRCRAFT DATA INDICATE THAT LEE HAS STRENGTHENED A
LITTLE DURING THE PAST SEVERAL HOURS WITH THE MAXIMUM WINDS NOW
NEAR 45 KT AND A CENTRAL PRESSURE NEAR 995 MB.  THE CYCLONE
CONTINUES TO HAVE AN ELONGATED CENTER OF CIRCULATION AND A LARGE
RADIUS OF MAXIMUM WINDS...AND THIS...COMBINED WITH THE GENERAL
APPEARANCE IN SATELLITE IMAGERY...SUGGESTS THAT LEE HAS AT LEAST
SOME CHARACTERISTICS OF A SUBTROPICAL CYCLONE.  ANALYSES FROM CIMSS
AT THE UNIVERSITY OF WISCONSIN SUGGEST THE STORM IS EXPERIENCING
ABOUT 15 KT OF WESTERLY VERTICAL WIND SHEAR DUE TO INTERACTION WITH
AN UPPER-LEVEL TROUGH VERY CLOSE TO THE SYSTEM...AND WATER VAPOR
IMAGERY SHOWS MID/UPPER-LEVEL DRY AIR OVER THE SOUTHWESTERN
QUADRANT OF THE STORM.
 
THE CENTER HAS TENDED TO REFORM FROM TIME TO TIME...WHICH MAKES THE
INITIAL MOTION OF 345/6 RATHER UNCERTAIN.  MOST TRACK MODEL
GUIDANCE NOW AGREES THAT LEE SHOULD MOVE SLOWLY FOR THE NEXT 48 HR
AS A RIDGE TO THE NORTH SLOWLY WEAKENS...FIRST GENERALLY NORTHWARD 
INTO SOUTHERN LOUISIANA AND THEN GENERALLY NORTHEASTWARD.  AFTER 48
HR...A DEEP-LAYER TROUGH APPROACHING FROM THE NORTH SHOULD CAUSE A
FASTER MOTION TOWARD THE NORTHEAST...ALTHOUGH THERE REMAINS SOME
SIGNIFICANT DISAGREEMENT BETWEEN THE MODELS ON THE EXACT SPEED. 
THE NEW FORECAST TRACK IS SHIFTED A LITTLE TO THE WEST OF THE
PREVIOUS TRACK BASED ON THE CURRENT POSITION AND MOTION...THEN LIES
NORTH OF THE PREVIOUS TRACK FROM 36 HOURS ONWARD.
 
GIVEN THAT THE CURRENT ISSUES WITH SHEAR AND DRY AIR HAVE NOT YET
SIGNIFICANTLY AFFECTED DEVELOPMENT...LEE IS EXPECTED TO CONTINUE
STRENGTHENING UNTIL LANDFALL.  WEAKENING AFTER LANDFALL IS LIKELY
TO BE SLOWER THAN NORMAL TO THE THE MARSHY NATURE OF THE LOUISIANA
COAST AND THE AMOUNT OF THE CIRCULATION THAT SHOULD REMAIN OVER
WATER.  LATER IN THE FORECAST PERIOD...LEE IS FORECAST TO MERGE
WITH AN ONCOMING COLD FRONT AND BECOME EXTRATROPICAL...A SOMEWHAT
UNUSUAL OCCURRENCE IN THIS AREA AT THIS TIME OF YEAR.

IT SHOULD BE NOTED THAT THE WINDS AND RAINS OF LEE EXTEND FAR FROM
THE CENTER...SO IT IS IMPORTANT NOT TO FOCUS TOO MUCH ON THE EXACT
FORECAST TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0900Z 28.8N  91.9W   45 KT  50 MPH
 12H  03/1800Z 29.3N  92.0W   50 KT  60 MPH
 24H  04/0600Z 30.0N  91.9W   55 KT  65 MPH...INLAND
 36H  04/1800Z 30.5N  91.5W   45 KT  50 MPH...INLAND
 48H  05/0600Z 31.0N  90.7W   40 KT  45 MPH...INLAND
 72H  06/0600Z 32.5N  88.5W   35 KT  40 MPH...INLAND
 96H  07/0600Z 35.0N  86.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  08/0600Z 37.0N  82.5W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 031453
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 AM CDT SAT SEP 03 2011
 
DATA FROM RECONNAISSANCE AIRCRAFT AND NOAA DOPPLER WEATHER RADARS
INDICATE THAT LEE HAS STRENGTHENED A LITTLE MORE THIS MORNING. LONG
PATCHES OF DOPPLER VELOCITIES OF 58-70 KT BETWEEN 2500-9500 FEET IN
AREAS OF 35-45 DBZ RADAR ECHOES HAVE BEEN NOTED OVER WATER AND OVER
LAND IN EXTREME SOUTHEASTERN LOUISIANA. RECON DATA ALSO INDICATED
60-KT 850 MB FLIGHT-LEVEL WINDS IN THE SAME GENERAL AREA AS THE
DOPPLER VELOCITIES. THIS INFORMATION SUPPORTS AN INTENSITY OF 50 KT.

THERE ARE TWO LOW-LEVEL CIRCULATION CENTERS APPARENT IN SATELLITE
IMAGERY...AND THE INITIAL POSITION AND FORWARD MOTION OF 005/05 KT
IS BASED ON THE MEAN POSITION BETWEEN THOSE TWO VORTICES...WHICH IS
CLOSE TO THE RECON 850 MB FLIGHT-LEVEL CENTER. THE GLOBAL AND
REGIONAL MODELS ARE GENERALLY IN GOOD AGREEMENT ON THE FORECAST
TRACK FOR THE NEXT 72 HOURS OR SO. UPPER-AIR DATA THIS MORNING
INDICATES THE WESTERN EDGE OF THE BLOCKING HIGH OVER THE
SOUTHEASTERN U.S. IS BEGINNING TO ERODE AS A SHORTWAVE TROUGH OVER
THE SOUTHERN AND CENTRAL U.S. PLAINS STATES MOVES SLOWLY EASTWARD.
WEAK SOUTHERLY FLOW DEVELOPING ON THE WEST SIDE OF THE RIDGE SHOULD
SLOWLY LIFT LEE NORTHWARD ACROSS CENTRAL LOUISIANA DURING THE NEXT
24 HOURS OR SO. AS THE TROUGH APPROACHES FROM THE WEST...LEE IS
FORECAST TO TURN TOWARD THE NORTHEAST AND ACCELERATE SLIGHTLY ON
DAYS 2-3. BY DAY 4...IF NOT SOONER...LEE IS EXPECTED TO MERGE WITH A
FRONTAL SYSTEM OVER THE SOUTHEASTERN UNITED STATES...WHICH IS VERY
ACLIMATOLOGICAL FOR THIS TIME OF THE YEAR. THE MODELS DIFFER
SIGNIFICANTLY WITH THE EVOLUTION AND FUTURE TRACK OF LEE ON DAYS 4
AND 5 WITH THE ECMWF KEEPING LEE UNDER A LARGE CUTOFF LOW FORECAST
TO DEVELOP OVER THE OHIO VALLEY...WHILE THE OTHER MODELS RACE
THE REMNANTS OF LEE OFF TO THE NORTHEAST UNDER A MORE PROGRESSIVE
MID-LATITUDE FLOW PATTERN. GIVEN THE RUN-TO-RUN CONSISTENCY OF THE
ECMWF THE PAST COUPLE OF DAYS...THE NHC TRACK LEANS TOWARD THE
ECMWF MODEL IN MOVING LEE MORE SLOWLY TO THE NORTHEAST ON DAYS 4
AND 5. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS
ADVISORY...AND LIES TO RIGHT OF THE NHC MODEL CONSENSUS USING THE
ECMWF MODEL TRACK SPEEDS.

LEE IS NOT EXPECTED TO STRENGTHEN MUCH...IF ANY...DUE TO THE
ENTRAINMENT OF AN ABUNDANCE OF VERY DRY AIR INTO THE SOUTHWESTERN
SEMICIRCLE OF THE CYCLONE. HOWEVER...DUE TO THE VERY LARGE SIZE OF
THE CIRCULATION...ONLY SLOW WEAKENING IS EXPECTED EVEN AFTER LEE
MOVES INLAND OVER LOUISIANA LATER TODAY. THE 34-KT WIND RADII WERE
EXPANDED IN THE NORTHEAST SEMICIRCLE BASED ON 43-KT SUSTAINED WINDS
REPORTED AT NOAA BUOY 42040.
 
IT SHOULD BE NOTED THAT THE WINDS AND RAINS OF LEE EXTEND FAR FROM
THE CENTER...SO IT IS IMPORTANT NOT TO FOCUS TOO MUCH ON THE EXACT
FORECAST TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/1500Z 29.3N  91.8W   50 KT  60 MPH
 12H  04/0000Z 29.7N  91.7W   50 KT  60 MPH
 24H  04/1200Z 30.3N  91.6W   50 KT  60 MPH...INLAND
 36H  05/0000Z 30.9N  91.1W   45 KT  50 MPH...INLAND
 48H  05/1200Z 31.4N  90.1W   40 KT  45 MPH...INLAND
 72H  06/1200Z 33.0N  87.5W   30 KT  35 MPH...INLAND
 96H  07/1200Z 35.0N  84.5W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  08/1200Z 37.5N  81.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 032054
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
400 PM CDT SAT SEP 03 2011
 
THE OVERALL CONVECTIVE ORGANIZATION OF LEE HAS NOT CHANGED SINCE THE
PREVIOUS ADVISORY. ALTHOUGH DOPPLER RADAR VELOCITIES ONLY SUPPORT
ABOUT 45 KT SURFACE WINDS...THE ASSUMPTION IS THAT STRONGER WINDS
EXIST IN THE DEEP CONVECTION IN THE SOUTHEAST QUADRANT OF THE
CIRCULATION THAT RECON AIRCRAFT WAS UNABLE TO INVESTIGATE THIS
AFTERNOON...AND WHICH LIES BEYOND THE RANGE OF THE GROUND-BASED
RADARS. SINCE THE PRESSURE HAS CONTINUED TO DROP AND IS NOW DOWN TO
989 MB...THE INITIAL INTENSITY IS BEING MAINTAINED AT 50 KT.

THE TWO LOW-LEVEL CIRCULATION CENTERS MENTIONED IN THE PREVIOUS
ADVISORY APPEAR TO HAVE CONSOLIDATED INTO ONE MAIN VORTEX NOW NEAR
MARSH ISLAND LOUISIANA. BASED ON THIS POSITION...THE INITIAL MOTION
ESTIMATE IS AN UNCERTAIN 360/03 KT. THE LATEST GLOBAL AND REGIONAL
MODELS...EXCLUDING THE HWRF MODEL...ARE IN MUCH BETTER AGREEMENT
NOW AND ARE SIMILAR TO THE PREVIOUS ECMWF MODEL SOLUTIONS. A
SHORTWAVE TROUGH OVER THE SOUTHERN AND CENTRAL U.S. PLAINS IS
EXPECTED TO MOVE SLOWLY EASTWARD AND ERODE THE WESTERN PORTION OF A
BLOCKING HIGH...WHICH WILL ALLOW LEE TO MOVE SLOWLY NORTHWARD FOR
THE NEXT 24 HOURS OR SO. AFTER THAT...HOWEVER...THE TROUGH IS
FORECAST TO BYPASS LEE AND LEAVE THE CYCLONE EMBEDDED ONCE AGAIN IN
WEAK STEERING FLOW. BY 72 HOURS...A SECOND TROUGH AND ASSOCIATED
COLD FRONT IS FORECAST TO NUDGE LEE SLOWLY TO THE NORTHEAST...AND
BEGIN TO INDUCE EXTRATROPICAL TRANSITION AS THE UPPER-LEVEL TROUGH
EVOLVES INTO A LARGE CUTOFF LOW OVER THE TENNESSEE AND OHIO VALLEYS
BY DAYS 4 AND 5. THE OFFICIAL FORECAST TRACK IS A LITTLE TO THE
RIGHT OF THE PREVIOUS ADVISORY TRACK...AND LIES BETWEEN THE NHC
MODEL CONSENSUS TRACK AND THE ECMWF TRACK.
 
SINCE THE CENTRAL PRESSURE HAS CONTINUED TO DECREASE...IT IS
POSSIBLE THAT LEE COULD STRENGTHEN SLIGHTLY WHEN CLOUD TOPS ARE
EXPECTED TO COOL IN THE LARGE BAND IN THE EASTERN SEMICIRCLE.
HOWEVER...THE OVERALL TREND CALLS FOR LEE TO REMAIN STEADY FOR THE
NEXT 12-24 HOURS...AND THEN SLOWLY WEAKEN AFTER THAT.
 
IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK OR WHERE
THE CENTER OF LEE EVENTUALLY MAKES LANDFALL SINCE THE STRONGEST
WINDS AND HEAVIEST RAINS EXTEND FAR FROM THE CENTER.

FORECAST POSITIONS AND MAX WINDS
 
INIT  03/2100Z 29.4N  92.1W   50 KT  60 MPH
 12H  04/0600Z 29.8N  91.9W   50 KT  60 MPH...INLAND
 24H  04/1800Z 30.2N  91.5W   50 KT  60 MPH...INLAND
 36H  05/0600Z 30.5N  91.1W   45 KT  50 MPH...INLAND
 48H  05/1800Z 31.2N  89.9W   40 KT  45 MPH...INLAND
 72H  06/1800Z 33.0N  87.2W   30 KT  35 MPH...INLAND
 96H  07/1800Z 34.5N  85.2W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  08/1800Z 37.0N  83.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 040254
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 PM CDT SAT SEP 03 2011
 
NATIONAL WEATHER SERVICE RADAR DATA AND SURFACE OBSERVATIONS
INDICATE THAT THE CENTER OF LEE HAS BEEN MEANDERING NEAR THE
SOUTHERN COAST OF LOUISIANA THIS EVENING.  AN OIL PLATFORM LOCATED
ABOUT 20 MILES WEST OF MARSH ISLAND HAS BEEN REPORTING A PRESSURE
OF AROUND 988 MB MOST OF THE EVENING.  THE WINDS AT THAT SITE WERE
VARIABLE FOR SEVERAL HOURS...BUT RECENTLY HAVE SHIFTED TO THE
SOUTHEAST AROUND 15-20 KT INDICATING THAT THE CENTER OF LEE REMAINS
OFFSHORE.  THE HIGHEST SUSTAINED WIND OBSERVATIONS DURING THE PAST
FEW HOURS ARE 40-44 KT AT SEVERAL ELEVATED RIGS OFF THE COAST OF
SOUTHWEST LOUISIANA.  BASED ON THESE OBSERVATIONS...THE INITIAL
INTENSITY IS SET AT 45 KT...WHICH COULD BE A LITTLE GENEROUS.  LEE
IS EXPECTED TO WEAKEN AS IT MOVES INLAND DURING THE NEXT DAY OR SO. 
HOWEVER...SINCE A LARGE PORTION OF THE CIRCULATION WILL REMAIN OVER
WATER...LEE WILL LIKELY REMAIN A TROPICAL STORM FOR ANOTHER 24 TO
36 HOURS.
 
LEE IS FORECAST TO DRIFT NORTHWARD DURING THE NEXT DAY OR SO AS A
SHORTWAVE TROUGH MOVES INTO THE NORTH-CENTRAL UNITED STATES.  AFTER
THAT TIME...THE CYCLONE IS EXPECTED TO INTERACT WITH A COLD FRONT
THAT SHOULD TURN LEE EASTWARD...THEN NORTHEASTWARD WITHIN 24 TO 36
HOURS.  BOTH THE GFS AND ECMWF MODELS SUGGEST LEE WILL BECOME AN
EXTRATROPICAL CYCLONE IN 2-3 DAYS...A SOMEWHAT UNUSUAL OCCURRENCE
IN THIS AREA AT THIS TIME OF YEAR.  THE GLOBAL MODELS AND THE
OFFICIAL FORECAST ALSO NOW INDICATE DISSIPATION OVER THE SOUTHERN
APPALACHIANS IN 4-5 DAYS.  THE OFFICIAL FORECAST HAS BEEN SHIFTED
WESTWARD THROUGH 24 HOURS DUE TO THE MORE WESTWARD INITIAL
POSITION...BUT THE REMAINDER OF THE TRACK IS ESSENTIALLY AN UPDATE
OF THE PREVIOUS FORECAST.
 
SINCE HEAVY RAINS AND STRONG WINDS EXTEND VERY FAR FROM THE
CENTER IT IS IMPORTANT NOT TO FOCUS ON THE EXACT FORECAST TRACK.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/0300Z 29.4N  92.6W   45 KT  50 MPH
 12H  04/1200Z 30.0N  92.5W   40 KT  45 MPH...INLAND
 24H  05/0000Z 30.4N  91.9W   40 KT  45 MPH...INLAND
 36H  05/1200Z 30.7N  90.9W   35 KT  40 MPH...INLAND
 48H  06/0000Z 32.0N  89.1W   30 KT  35 MPH...INLAND
 72H  07/0000Z 34.0N  86.5W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  08/0000Z 36.5N  84.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
120H  09/0000Z...DISSIPATED
 
$$
FORECASTER BROWN
 

WTNT43 KNHC 040842
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
400 AM CDT SUN SEP 04 2011

SURFACE OBSERVATIONS AND WSR-88D RADAR DATA INDICATE THAT LEE IS
VERY NEAR THE SOUTHERN COAST OF LOUISIANA.  THE INTENSITY HAS BEEN
REDUCED TO 40 KT WHICH IS A LITTLE ABOVE ALL AVAILABLE SUSTAINED
SURFACE WIND OBSERVATIONS...ALTHOUGH SOMEWHAT HIGHER WINDS ARE
STILL OCCURRING AT ELEVATED PLATFORMS IN THE GULF OF MEXICO.  LEE
WILL BE MOVING OVER THE FLAT TERRAIN OF EXTREME SOUTHERN LOUISIANA
TODAY...WITH A LARGE PORTION OF THE CIRCULATION REMAINING OVER
WATER.  THEREFORE...THE CYCLONE IS FORECAST TO WEAKEN MORE SLOWLY
THAN INDICATED BY THE TYPICAL INLAND DECAY RATE...AND THE INTENSITY
FORECAST IS A LITTLE ABOVE THE LATEST LGEM GUIDANCE.  BY 48 HOURS OR
SOONER...THE GFS AND ECMWF MODELS SHOW THE SYSTEM EMBEDDED WITHIN A
FRONTAL ZONE...AND THE OFFICIAL FORECAST SHOWS EXTRATROPICAL
TRANSITION TO HAVE OCCURRED BY THAT TIME.  BASED ON GUIDANCE FROM
THOSE SAME GLOBAL MODELS...DISSIPATION IS LIKELY AFTER 96 HOURS.

THE CURRENT MOTION IS A NORTHWARD DRIFT OR ABOUT 360/2.  LEE IS IN A
COL REGION OF THE MID-TROPOSPHERIC FLOW...I.E. WITHIN VERY WEAK
STEERING CURRENTS...AT THIS TIME.  A TROUGH OVER THE NORTH-CENTRAL
U.S. IS FORECAST TO DIG SOUTHEASTWARD OVER THE NEXT DAY OR SO.  THE
FLOW ON THE SOUTHERN SIDE OF THE TROUGH IS EXPECTED TO TURN THE
TROPICAL CYCLONE TOWARD THE NORTHEAST AND EAST-NORTHEAST DURING THE
NEXT 24 TO 36 HOURS.  LATER IN THE PERIOD...THE POST-TROPICAL
CYCLONE SHOULD TURN TO THE LEFT AS IT MOVES ON THE SOUTHEAST SIDE
OF THE TROUGH.  THE OFFICIAL TRACK FORECAST IS JUST A LITTLE TO THE
SOUTH OF THE PREVIOUS ONE DURING THE FIRST COUPLE OF DAYS AND VERY
SIMILAR THEREAFTER.  THIS IS ALSO FAIRLY CLOSE TO THE GFS FORECAST.
 
SINCE HEAVY RAINS AND STRONG WINDS EXTEND VERY FAR FROM THE
CENTER...IT IS IMPORTANT NOT TO FOCUS ON THE EXACT LOCATION OF THE
CENTER OF LEE.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/0900Z 29.6N  92.5W   40 KT  45 MPH
 12H  04/1800Z 30.0N  92.3W   35 KT  40 MPH...INLAND
 24H  05/0600Z 30.3N  91.5W   30 KT  35 MPH...INLAND
 36H  05/1800Z 30.8N  90.1W   30 KT  35 MPH...INLAND
 48H  06/0600Z 32.0N  88.4W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  07/0600Z 34.5N  86.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  08/0600Z 37.0N  84.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
120H  09/0600Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT43 KNHC 041451
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 AM CDT SUN SEP 04 2011
 
SURFACE OBSERVATIONS AND WSR-88D RADAR DATA INDICATE THAT LEE
FINALLY MOVED INLAND OVER SOUTH-CENTRAL LOUISIANA THIS MORNING
AROUND 11Z ABOUT 10 NMI SOUTH OF INTRACOASTAL CITY. RECENT DOPPLER
RADAR DATA INDICATE BANDS OF CONVECTION HAVE FORMED OVER
SOUTHEASTERN LOUISIANA AND NEAR THE FLORIDA PANHANDLE AND EXTEND
SOUTHWESTWARD OVER THE GULF OF MEXICO. SOME OF THESE BANDS HAVE
CONTAINED DOPPLER VELOCITIES OF 65-72 KT FROM 8000-12000 FT IN
35-45 DBZ ECHOES...WITH MEAN VALUES OF AT LEAST 60 KT. ALTHOUGH
THESE DOPPLER VELOCITY VALUES WOULD TYPICALLY EQUATE TO SURFACE
WINDS OF 50-55 KT...THE SHORT-LIVED NATURE OF THESE NEW CONVECTIVE
BANDS SUGGESTS THAT ANY HIGHER WIND SPEEDS WILL LIKELY BE VERY
TRANSIENT. THE INITIAL INTENSITY IS BEING MAINTAINED AT 40 KT BASED
ON WIND REPORTS FROM NOAA BUOY 42040...BUT THE GUST DIFFERENTIAL IN
THE FORECAST/ADVISORY PRODUCT HAS BEEN INCREASED TO 55 KT FROM THE
STANDARD 50-KT GUST VALUE IN ORDER TO ACCOUNT FOR THE STRONGER
DOPPLER VELOCITIES THAT HAVE BEEN OBSERVED.

LEE IS DRIFTING SLOWLY TO THE NORTHEAST...OR 040/03 KT. THERE IS NO
SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK REASONING. LEE IS
EXPECTED TO REMAIN EMBEDDED IN A WEAK STEERING FLOW REGIME FOR THE
NEXT 24 HOURS OR SO AND ONLY DRIFT SLOWLY EAST-NORTHEASTWARD TO
NORTHEASTWARD. AFTER THAT...A VIGOROUS SHORTWAVE TROUGH IS
FORECAST TO DIG SOUTHEASTWARD FROM THE NORTHERN AND CENTRAL PLAINS
AND GRADUALLY LIFT LEE NORTHEASTWARD AT A FASTER FORWARD SPEED...
BUT STILL AT LESS THAN 10 KT. BY 48 HOURS...LEE IS EXPECTED TO MERGE
WITH A FAIRLY BRISK FRONTAL SYSTEM FOR THIS TIME OF THE YEAR...AND
BECOME A LARGE SLOW-MOVING EXTRATROPICAL LOW PRESSURE SYSTEM OVER
THE TENNESSEE VALLEY. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY...EXCEPT THAT THE FORWARD SPEED WAS DECREASED
AFTER 48 HOURS...AND CLOSELY FOLLOWS THE CONSENSUS TRACK MODELS...
TVCN AND TVCA.
 
LEE WILL BE MOVING OVER THE RAIN-SATURATED FLAT TERRAIN OF SOUTHERN
AND SOUTHEASTERN LOUISIANA TODAY...WITH A LARGE PORTION OF THE
CIRCULATION REMAINING OVER WATER. AFTERNOON HEATING SHOULD ALSO
GENERATE DEEP CONVECTION OVER LAND AND NEAR THE CENTER OF
CIRCULATION...WHICH COULD ADD SOME ENERGY TO THE CYCLONE. AS A
RESULT...THE TROPICAL STORM IS EXPECTED TO WEAKEN MORE SLOWLY
THAN INDICATED BY THE TYPICAL INLAND DECAY RATE FOR INLAND TROPICAL
CYCLONES. 
 
SINCE HEAVY RAINS...STRONG WINDS...AND THE HIGHEST STORM SURGE
VALUES ARE OCCURRING VERY FAR FROM THE CENTER...IT IS IMPORTANT NOT
TO FOCUS ON THE EXACT LOCATION OF THE CENTER OF LEE. THE PRIMARY 
THREAT FROM LEE WILL BE EXTREMELY HEAVY RAINFALL OVER MUCH OF THE
SOUTHEASTERN U.S. DURING NEXT SEVERAL DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/1500Z 29.9N  91.9W   40 KT  45 MPH...INLAND
 12H  05/0000Z 30.1N  91.5W   35 KT  40 MPH...INLAND
 24H  05/1200Z 30.6N  90.4W   30 KT  35 MPH...INLAND
 36H  06/0000Z 31.4N  88.9W   30 KT  35 MPH...INLAND
 48H  06/1200Z 32.6N  87.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  07/1200Z 34.5N  86.5W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  08/1200Z 36.5N  86.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
120H  09/1200Z...DISSIPATED
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 042105
TCDAT3
 
TROPICAL STORM LEE DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
400 PM CDT SUN SEP 04 2011
 
WSR-88D RADAR DATA AND SATELLITE IMAGERY INDICATE THAT LEE HAS
BECOME A LITTLE BETTER ORGANIZED EVEN THOUGH THE CENTER IS WELL
INLAND NOW OVER SOUTH-CENTRAL LOUISIANA. OTHER THAN THE STRONG
BURST OF DEEP CONVECTION THAT HAS DEVELOPED NEAR THE SURFACE
CENTER...NARROW BANDS OF MODEST CONVECTION CONTINUE TO FORM OVER
SOUTHEASTERN LOUISIANA AND NEAR THE FLORIDA PANHANDLE...WHICH EXTEND
SOUTHWARD OVER THE GULF OF MEXICO FOR A COUPLE HUNDRED MILES. SOME
OF THESE BANDS HAVE CONTAINED DOPPLER VELOCITIES OF 60-68 KT FROM
4500-10000 FT IN 25-35 DBZ ECHOES...WITH MEAN VALUES OF ABOUT 55
KT. ALTHOUGH THESE DOPPLER VELOCITY VALUES WOULD TYPICALLY
TRANSLATE TO SURFACE WINDS OF 45-50 KT...THE WEAK ECHO RETURNS
SUGGEST THAT HIGHER WIND SPEEDS WILL MAINLY OCCUR IN GUSTS. THE
INITIAL INTENSITY IS BEING MAINTAINED AT 40 KT BASED ON SUSTAINED
WIND REPORT OF 40 KT FROM THE BURAS C-MAN STATION...AND THE GUST
DIFFERENTIAL IN THE FORECAST/ADVISORY PRODUCT REMAINS AT 55 KT...
WHICH IS A LITTLE HIGHER THAN THE STANDARD 50-KT GUST VALUE IN
ORDER TO ACCOUNT FOR THE TRANSIENT STRONGER WINDS ALOFT NOTED IN
DOPPLER VELOCITY DATA.
 
LEE HAS BEEN MOVING TO THE NORTH OVER THE PAST 6 HOURS. HOWEVER...
THE CYCLONE IS EXPECTED TO SLOW DOWN AND TURN TO THE NORTHEAST OR
EAST-NORTHEAST WITHIN THE NEXT 6 TO 12 HOURS. OTHERWISE...THERE IS
NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK FORECAST REASONING. A
VIGOROUS SHORTWAVE TROUGH OVER THE NORTHERN AND CENTRAL PLAINS IS
EXPECTED TO CONTINUE DIGGING SOUTHEASTWARD AND GRADUALLY LIFT OUT
TO THE NORTHEAST AT A SLIGHTLY FASTER FORWARD SPEED. BY 36 HOURS...
A PIECE OF ENERGY FROM THE SHORTWAVE IS FORECAST BY ALL OF THE
MODELS TO BREAK OFF AND BECOME ABSORBED INTO THE CIRCULATION. THIS
MID-LEVEL BAROCLINIC INTERACTION...COUPLED WITH ABSORPTION BY A
FRONTAL SYSTEM...IS EXPECTED TO TRANSITION LEE INTO A LARGE
LOW-LATITUDE EXTRATROPICAL LOW PRESSURE SYSTEM OVER THE TENNESSEE
VALLEY BY DAYS 2-4. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY AND CLOSELY FOLLOWS THE CONSENSUS TRACK MODELS...
TVCN AND TVCA.
 
ALL OF THE GLOBAL AND REGIONAL MODELS ARE NOW FORECASTING LEE TO
REMAIN A TROPICAL STORM OR EXTRATROPICAL GALE AREA FOR THE NEXT 36
HOURS OR SO AS THE CYCLONE GETS A SHOT OF BAROCLINIC ENERGY FROM AN
UPSTREAM SHORTWAVE TROUGH. THIS TREND WAS FOLLOWED IN THE OFFICIAL
INTENSITY FORECAST...AND IS A BLEND OF THE INTENSITY CONSENSUS
MODEL ICON...AND INPUT FROM THE NHC TAFB UNIT.
 
SINCE HEAVY RAINS...STRONG WINDS...AND THE HIGHEST STORM SURGE
VALUES ARE OCCURRING VERY FAR FROM THE CENTER...IT IS IMPORTANT NOT
TO FOCUS ON THE EXACT LOCATION OF THE CENTER OF LEE. THE PRIMARY
THREAT FROM LEE WILL BE EXTREMELY HEAVY RAINFALL OVER MUCH OF THE
SOUTHEASTERN U.S. DURING NEXT SEVERAL DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  04/2100Z 30.6N  91.8W   40 KT  45 MPH
 12H  05/0600Z 30.7N  91.0W   35 KT  40 MPH...INLAND
 24H  05/1800Z 31.2N  89.6W   35 KT  40 MPH...INLAND
 36H  06/0600Z 32.3N  88.3W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  06/1800Z 33.3N  87.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  07/1800Z 34.8N  86.8W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  08/1800Z 36.0N  86.8W   20 KT  25 MPH...POST-TROP/EXTRATROP
120H  09/1800Z...DISSIPATED
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 050238
TCDAT3
 
TROPICAL DEPRESSION LEE DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL132011
1000 PM CDT SUN SEP 04 2011
 
LAND INTERACTION AND CONTINENTAL AIR SEEN IN THE GOES SOUNDER
AIRMASS PRODUCT WRAPPING INTO THE WESTERN SIDE OF THE CIRCULATION
HAVE TAKEN A TOLL ON LEE THIS EVENING. DEEP CONVECTION HAS
DECREASED BOTH NEAR THE CENTER AND OFFSHORE AND WINDS HAVE STEADILY
DECREASED BELOW TROPICAL STORM FORCE...EVEN AT THE ELEVATED OIL
PLATFORMS OVER THE NORTHERN GULF OF MEXICO. THEREFORE THE INITIAL
INTENSITY HAS BEEN REDUCED TO 30 KT...WITH THESE WINDS FOUND ONLY
WELL SOUTH AND EAST OF THE CENTER OVER WATER.  

LEE IS ALREADY BEGINNING TO LOSE TROPICAL CHARACTERISTICS WITH
WARM/COASTAL FRONTOGENESIS UNDERWAY EAST OF THE CENTER AND THE
SURFACE CENTER BECOMING ELONGATED FROM SOUTHWEST TO NORTHEAST IN
THE PRESSURE AND WIND FIELDS. AS THE CYCLONE BEGINS TO INTERACT
WITH AN UNUSUALLY STRONG MID/UPPER-LEVEL TROUGH DIGGING INTO THE
MISSISSIPPI VALLEY...LEE SHOULD BE EXTRATROPICAL BY 24 HOURS WHEN
GLOBAL MODELS SHOW THE LOW EMBEDDED IN A LOW-LEVEL BAROCLINIC ZONE
AND THE CIRCULATION MERGING WITH A MID-LATITUDE SHORTWAVE TROUGH.
AS THIS TRANSITION OCCURS...THE GFS AND ECMWF MODELS SHOW A 6-12
HOUR PERIOD OF GALE-FORCE WINDS OVER THE GULF WATERS SOUTHEAST OF
THE CENTER...AND THIS IS INDICATED IN THE OFFICIAL FORECAST. THIS
HAZARD WILL BE HANDLED BY MARINE PRODUCTS FROM LOCAL NATIONAL
WEATHER SERVICE OFFICES AND THE NATIONAL HURRICANE CENTER. AFTER
EXTRATROPICAL TRANSITION...THE CYCLONE SHOULD SLOWLY WEAKEN AND
DISSIPATE BY 72 HOURS. 

LEE HAS MADE ITS TURN TOWARD THE EAST-NORTHEAST...WITH AN INITIAL
MOTION ESTIMATE OF 060/06. AS THE THE SHORTWAVE TROUGH CUTS OFF
INTO A CLOSED LOW OVER THE TENNESSEE VALLEY...LEE WILL TURN TOWARD
THE NORTHEAST AND THEN THE NORTH-NORTHEAST OVER THE NEXT 48 HOURS
AS IT IS ABSORBED INTO THE CIRCULATION OF THE CUTOFF. THE NEW TRACK
FORECAST IS A LITTLE TO THE LEFT OF AND FASTER THAN THE PREVIOUS
ONE...SHOWING A SHARPER TURN BACK TOWARD THE NORTH...AND IS CLOSE
TO A BLEND OF THE GFS AND ECMWF.   

THE MAIN HAZARD FROM LEE AND ITS REMNANTS WILL BE VERY HEAVY
RAINFALL SPREADING FROM THE CENTRAL GULF COAST STATES INTO THE
TENNESSEE VALLEY AND SOUTHERN APPALACHIANS IN THE NEXT FEW DAYS.
PLEASE SEE PRODUCTS FROM YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE
ON THE HEAVY RAINFALL AND FLOODING THREAT. 
 
THIS IS THE LAST NHC ADVISORY ON LEE. FUTURE INFORMATION ON THIS
SYSTEM CAN BE FOUND IN PUBLIC ADVISORIES ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER...UNDER AWIPS HEADER TCPAT3
AND WMO HEADER WTNT33 KWNH...BEGINNING AT 4 AM CDT. FOR MARINE
INTERESTS ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN
HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER
AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. 

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/0300Z 31.0N  91.4W   30 KT  35 MPH
 12H  05/1200Z 31.3N  90.5W   35 KT  40 MPH...POST-TROPICAL
 24H  06/0000Z 32.3N  88.8W   30 KT  35 MPH...POST-TROP/EXTRATROP
 36H  06/1200Z 33.6N  87.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  07/0000Z 34.8N  86.9W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  08/0000Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

