WTNT41 KNHC 130837
TCDAT1
 
TROPICAL STORM FRANKLIN DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062011
500 AM EDT SAT AUG 13 2011
 
DURING THE PAST SEVERAL HOURS...SATELLITE IMAGES INDICATE THAT A
LARGE BURST OF CONVECTION FORMED NEAR OR JUST TO THE EAST OF THE
CENTER.  AN AMSR-E MICROWAVE PASS AT 0553 UTC SUGGESTS THE CENTRAL
FEATURES OF THE SYSTEM WERE BECOMING BETTER-DEFINED WITH MORE
CURVATURE NOTED.  DVORAK SATELLITE ESTIMATES WERE 30 KT AND 35 KT
FROM TAFB/SAB WITH AN AMSU-BASED ESTIMATE FROM UW-CIMSS OF 37 KT. 
GIVEN THE SIGNIFICANT INCREASE IN THE CONVECTION AND STRUCTURAL
IMPROVEMENTS IN MICROWAVE IMAGERY...THE INTENSITY IS SET TO 35
KT...MAKING THIS SYSTEM THE SIXTH TROPICAL STORM OF THE YEAR.
 
FRANKLIN DOES NOT HAVE MUCH TIME LEFT TO INTENSIFY AS IT WILL SOON
BE CROSSING THE 26C ISOTHERM.  VERTICAL WIND SHEAR IS ALSO FORECAST
TO INCREASE DUE TO AN UPPER-LEVEL TROUGH CATCHING THE STORM FROM
BEHIND.  THUS...ONLY A SMALL INCREASE IN STRENGTH IS SHOWN IN THE
NHC FORECAST...SIMILAR TO A BLEND OF THE SHIPS AND LGEM MODELS.  IT
SHOULD BE NOTED THAT THESE TYPES OF NORTHEASTWARD MOVING SYSTEMS
HAVE HISTORICALLY BEEN DIFFICULT TO FORECAST...AND IT WOULD NOT BE
SURPRISING IF THE STORM BRIEFLY BECOMES A LITTLE STRONGER THAN
PREDICTED.  
 
THE INITIAL MOTION HAS TURNED A LITTLE TO THE LEFT AND IS ESTIMATED
AT 055/17.  FRANKLIN IS BEING STEERED ALONG THE NORTHWESTERN
PERIPHERY OF THE SUBTROPICAL RIDGE WITHIN MID-LATITUDE WEST-
SOUTHWESTERLY FLOW.  MODEL GUIDANCE IS TIGHTLY CLUSTERED ON A TRACK
TOWARD THE EAST-NORTHEAST TODAY...FOLLOWED BY A MOTION TOWARD THE
EAST AS THE STORM MOVES AROUND THE RIDGE.  THE LATEST FORECAST IS
BASICALLY AN UPDATE OF THE PREVIOUS NHC ADVISORY...AND LIES JUST TO
THE NORTH OF THE ATLANTIC MULTI-MODEL CONSENSUS.  A COLD FRONT CAN
BE SEEN A FEW HUNDRED MILES TO THE NORTHWEST OF FRANKLIN...AND THIS
FEATURE...ALONG WITH COOLER SSTS AND INCREASING SHEAR...SHOULD
CAUSE EXTRATROPICAL TRANSITION WITHIN ABOUT 24 HOURS.  THE SYSTEM
SMALL SYSTEM SHOULD BECOME ABSORBED BY THE FRONT IN ABOUT 3 DAYS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/0900Z 37.9N  60.4W   35 KT  40 MPH
 12H  13/1800Z 39.0N  57.4W   40 KT  45 MPH
 24H  14/0600Z 40.0N  52.9W   40 KT  45 MPH...POST-TROP/EXTRATROP
 36H  14/1800Z 40.4N  48.3W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  15/0600Z 40.0N  43.7W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  16/0600Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT41 KNHC 131434
TCDAT1
 
TROPICAL STORM FRANKLIN DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062011
1100 AM EDT SAT AUG 13 2011
 
SINCE THE LAST ADVISORY...A SIGNIFICANT BURST OF DEEP CONVECTION HAS
PERSISTED NEAR AND JUST NORTH OF THE CENTER OF FRANKLIN. PASSIVE
MICROWAVE SATELLITE IMAGES INDICATED A PRONOUNCED MID-LEVEL
EYE-LIKE FEATURE HAD DEVELOPED BETWEEN 08Z AND 10Z...AND THAT COULD
BE WHEN FRANKLIN POSSIBLY REACHED A PEAK INTENSITY OF NEAR 45 KT.
SINCE THAT TIME...HOWEVER...THE CONVECTIVE PATTERN HAS ERODED
SOMEWHAT DUE TO THE EFFECTS OF INCREASING SOUTHWESTERLY UPPER-LEVEL
SHEAR AND COOLER WATER BENEATH THE CYCLONE. THE INITIAL INTENSITY
OF 40 KT IS BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF
T3.0/45 KT FROM TAFB...T2.5/35 KT FROM SAB...38 KT FROM
CIRA-AMSU...AND 39 KT FROM UW-CIMSS ADT.

THE INITIAL MOTION ESTIMATE IS 060/19 BASED PRIMARILY ON MICROWAVE
SATELLITE FIXES. FRANKLIN IS EMBEDDED WITHIN DEEP WESTERLY
MID-LATITUDE FLOW AHEAD OF A LARGE MID-TROPOSPHERIC TROUGH THAT IS
MOVING EASTWARD OFF OF THE U.S. NEW ENGLAND COAST. THIS PROGRESSIVE
PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT FEW DAYS...WHICH
SHOULD KEEP FRANKLIN MOVING IN A GENERAL EASTERLY DIRECTION. THE
OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY TRACK
AND IS NEAR THE CENTER OF THE TIGHTLY PACKED NHC MODEL GUIDANCE.

FRANKLIN LIKELY PEAKED EARLIER THIS MORNING AND IS NOW ENTERING A
WEAKENING PHASE AS IT MOVES OVER WATER COOLER THAN 26C AND WESTERLY
VERTICAL WIND SHEAR GRADUALLY INCREASES. FRANKLIN IS FORECAST TO
MERGE WITH A COLD FRONT IN 24-36 HOURS INDUCING EXTRATROPICAL
TRANSITION...BUT IT APPEARS THAT THERE WILL NOT BE ENOUGH
BAROCLINIC ENERGY TO CAUSE FRANKLIN TO RE-STRENGTHEN AS A
SIGNIFICANT EXTRATROPICAL LOW PRESSURE SYSTEM. THE INTENSITY
FORECAST IS IDENTICAL TO THE PREVIOUS ADVISORY AND REMAINS LOWER
THAN ALL OF THE AVAILABLE INTENSITY GUIDANCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/1500Z 39.0N  57.9W   40 KT  45 MPH
 12H  14/0000Z 39.9N  54.7W   40 KT  45 MPH
 24H  14/1200Z 40.6N  50.2W   40 KT  45 MPH...POST-TROP/EXTRATROP
 36H  15/0000Z 40.6N  45.6W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  15/1200Z 40.0N  41.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 72H  16/1200Z...DISSIPATED
 
$$
FORECASTER STEWART
 

WTNT41 KNHC 132033
TCDAT1
 
TROPICAL STORM FRANKLIN DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL062011
500 PM EDT SAT AUG 13 2011
 
AFTER THE MORNING FLARE UP OF DEEP CONVECTION NEAR THE CENTER OF
FRANKLIN...INCREASING VERTICAL SHEAR AND COLDER WATER HAVE STARTED
TAKING THEIR TOLL ON THE CYCLONE THIS AFTERNOON. CONVECTION IS NOW
SHEARED MORE THAN 90 NMI FROM THE CENTER AND THE LOW-LEVEL CENTER
HAS BECOME FULLY EXPOSED. FRANKLIN IS QUICKLY TAKING ON THE
APPEARANCE OF A POST TROPICAL/EXTRATROPICAL LOW PRESSURE SYSTEM.
THE INITIAL INTENSITY IS DECREASED TO 35 KT BASED ON A TAFB
SATELLITE DATA-T NUMBER OF T2.5/35 KT.

THE INITIAL MOTION ESTIMATE IS NOW 070/19. FRANKLIN SHOULD CONTINUE
TO GRADUALLY TURN TOWARD THE EAST AS IT REMAINS EMBEDDED WITHIN
WESTERLY LOW- TO MID-LEVEL FLOW AHEAD OF A MID-TROPOSPHERIC TROUGH.
AS THE CYCLONE WEAKENS AND BECOMES MORE VERTICALLY SHALLOW...
FRANKLIN SHOULD DECELERATE AND BE STEERED TOWARD THE EAST-SOUTHEAST
BY WEAKER LOW-LEVEL FLOW IN THE LATTER FORECAST PERIODS. THE NHC
FORECAST TRACK IS SIMILAR TO BUT SLIGHTLY SOUTH AND SLOWER THAN THE
PREVIOUS ADVISORY...AND CLOSELY FOLLOWS THE NHC DYNAMICAL MODEL
CONSENSUS.
 
FRANKLIN IS CURRENTLY OVER 25C SST WATER AND COOLER WATER LIES AHEAD
OF THE CYCLONE FOR AT LEAST THE NEXT 36 HOURS. THE COMBINATION OF
INCREASING WESTERLY VERTICAL WIND SHEAR AND COLDER WATER SHOULD
INHIBIT THE DEVELOPMENT OF ANY SIGNIFICANT DEEP CONVECTION NEAR THE
EXPOSED LOW-LEVEL CENTER. AS A RESULT...FRANKLIN COULD BECOME FULLY
EXTRATROPICAL WITHIN THE NEXT 12 HOURS OR SO. THE POST-TROPICAL
REMNANT LOW IS THEN EXPECTED TO MERGE WITH A COLD FRONT IN 24
HOURS...AND IT STILL APPEARS THAT THERE WILL NOT BE ENOUGH
BAROCLINIC ENERGY TO CAUSE FRANKLIN TO RE-STRENGTHEN AS A
SIGNIFICANT EXTRATROPICAL LOW PRESSURE SYSTEM. THE INTENSITY
FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND REMAINS LOWER THAN
ALL OF THE NHC INTENSITY GUIDANCE.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  13/2100Z 39.7N  55.5W   35 KT  40 MPH
 12H  14/0600Z 40.2N  51.9W   35 KT  40 MPH...POST-TROP/EXTRATROP
 24H  14/1800Z 40.3N  47.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 36H  15/0600Z 39.9N  43.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
 48H  15/1800Z 38.8N  40.7W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  16/1800Z...DISSIPATED
 
$$
FORECASTER STEWART
 

