WTNT43 KNHC 160835
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST THU AUG 16 2012
 
SATELLITE IMAGES INDICATE THAT A SMALL CENTRAL DENSE OVERCAST HAS
FORMED NEAR THE CENTER OF THE CYCLONE.  MICROWAVE DATA ALSO SUGGEST
THAT THE CENTRAL FEATURES OF THE SYSTEM HAVE BECOME BETTER DEFINED. 
THEREFORE...THE INITIAL INTENSITY IS INCREASED TO 35 KT...IN BEST
AGREEMENT WITH THE TAFB SATELLITE ESTIMATE.  GORDON SHOULD BE
MOVING OVER RELATIVELY WARM WATER AND WITHIN A LIGHT-TO-MODERATE
SHEAR ENVIRONMENT FOR THE NEXT COUPLE OF DAYS.  ALMOST ALL OF THE
GUIDANCE SHOWS THE STORM CLOSE TO OR BECOMING A HURRICANE WITHIN 72
HRS.  THE NHC INTENSITY FORECAST IS SLIGHTLY INCREASED FROM THE
PREVIOUS ONE...BUT REMAINS BELOW THE INTENSITY CONSENSUS FROM 48-72
HR...AND IS NEAR A BLEND OF THE SHIPS/LGEM MODELS.
 
GORDON APPEARS TO HAVE RECURVED AND IS MOVING ABOUT 015/12 KT.  THE
STORM IS EXPECTED TO BE STEERED NORTHEASTWARD THEN EASTWARD AROUND
THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE DURING THE NEXT
COUPLE OF DAYS.  AFTER THAT TIME...GORDON SHOULD INTERACT MORE WITH
THE MID-LATITUDE WESTERLIES AND THEN TURN TOWARD THE NORTHEAST AHEAD
OF A TROUGH.  WHILE THE MODELS ARE IN GOOD AGREEMENT...THERE HAS
BEEN A SOUTHWARD ADJUSTMENT TO THE TRACK IN THE MAJORITY OF THE
GUIDANCE...AND THE NHC FORECAST IS SHIFTED IN THAT DIRECTION.
WHILE GORDON IS EXPECTED TO BE NEAR THE AZORES IN ABOUT 4 DAYS...
MOST OF THE MODELS SUGGEST THAT IT WILL BE EXTRATROPICAL AT THAT
TIME.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/0900Z 32.2N  54.8W   35 KT  40 MPH
 12H  16/1800Z 33.5N  53.4W   45 KT  50 MPH
 24H  17/0600Z 34.6N  50.2W   50 KT  60 MPH
 36H  17/1800Z 34.5N  46.3W   55 KT  65 MPH
 48H  18/0600Z 34.4N  42.5W   65 KT  75 MPH
 72H  19/0600Z 35.0N  34.5W   65 KT  75 MPH
 96H  20/0600Z 36.8N  27.0W   55 KT  65 MPH...POST-TROP/EXTRATROP
120H  21/0600Z 39.5N  20.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 161433
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 AM AST THU AUG 16 2012
 
VISIBLE SATELLITE IMAGERY INDICATES TIGHTLY CURVED CONVECTIVE BANDS
HAVE FORMED AROUND A SMALL CENTRAL DENSE OVERCAST...WHICH INDICATES
THAT GORDON IS STRENGTHENING. SATELLITE INTENSITY ESTIMATES ARE
T3.0 FROM TAFB...T2.5 FROM SAB...AND T2.7 ADT FROM UW-CIMSS. GIVEN
THE MID-LEVEL BANDED EYE FEATURE NOTED IN A 16/1143 UTC SSMIS
MICROWAVE IMAGE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 45
KT...WHICH IS SUPPORTED BY THE 45-KT TAFB INTENSITY ESTIMATE.

GORDON IS RECURVING TO THE NORTHEAST...AND THE INITIAL MOTION IS NOW
045/14 KT. THE CYCLONE HAS ROUNDED THE SUBTROPICAL RIDGE AXIS AND
WILL BE MOVING INTO THE MID-LATITUDE WESTERLIES DURING THE NEXT
12-24 HOURS. AS A RESULT...GORDON SHOULD GRADUALLY TURN TOWARD THE
EAST THROUGH 72 HOURS. AFTER THAT TIME...THE CYCLONE IS EXPECTED TO
LIFT OUT TOWARD THE NORTHEAST AHEAD OF A DIGGING SHORTWAVE TROUGH
AND BE NEAR THE AZORES ISLANDS IN ABOUT 4 DAYS. THE NHC MODEL
GUIDANCE IS TIGHTLY PACKED AROUND THE PREVIOUS FORECAST TRACK... 
SO ONLY MINOR TWEAKS WERE MADE FOR THIS ADVISORY.

SATELLITE IMAGERY INDICATES THAT UPPER-LEVEL OUTFLOW HAS BECOME WELL
ESTABLISHED IN ALL QUADRANTS...ESPECIALLY IN THE NORTHEASTERN
SEMICIRCLE. THE VERTICAL SHEAR IS FORECAST TO REMAIN FAVORABLE FOR
ABOUT THE NEXT 36 HOURS AND WARM SEA-SURFACE TEMPERATURES OF AT
LEAST 27C LIE AHEAD OF THE CYCLONE. AS A RESULT OF THESE FAVORABLE
CONDITIONS...STEADY INTENSIFICATION SEEMS REASONABLE ALTHOUGH DRY
MID-LEVEL AIR IS BEGINNING TO ENCROACH FROM THE WEST. BY 48
HOURS...WESTERLY WIND SHEAR AND DRY AIR ENTRAINMENT ARE EXPECTED TO
SHARPLY INCREASE...WHICH SHOULD ACT TO PUT A BRAKE ON THE
STRENGTHENING PROCESS. AS GORDON APPROACHES THE AZORES IN 4 DAYS...
THE SYSTEM COULD MERGE WITH A FRONTAL SYSTEM AND TRANSITION INTO A
STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS IDENTICAL
TO THE PREVIOUS ADVISORY...AND IS CLOSE TO INTENSITY CONSENSUS
MODEL...IV15.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/1500Z 33.3N  53.8W   45 KT  50 MPH
 12H  17/0000Z 34.3N  51.8W   50 KT  60 MPH
 24H  17/1200Z 34.9N  48.3W   55 KT  65 MPH
 36H  18/0000Z 34.9N  44.5W   60 KT  70 MPH
 48H  18/1200Z 34.8N  40.6W   65 KT  75 MPH
 72H  19/1200Z 35.6N  32.7W   60 KT  70 MPH
 96H  20/1200Z 37.9N  25.5W   50 KT  60 MPH...POST-TROP/EXTRATROP
120H  21/1200Z 40.4N  19.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 162040
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST THU AUG 16 2012
 
GORDON HAS BEEN STRENGTHENING OVER THE PAST 12 HOURS. VISIBLE
SATELLITE IMAGERY CONTINUES TO SHOW TIGHTLY COILED CONVECTIVE CLOUD
BANDS SPIRALING INTO A SMALL CENTRAL DENSE OVERCAST FEATURE.
SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T3.0/45 KT
FROM SAB...AND T2.7/39 KT ADT FROM UW-CIMSS. AN 1143 UTC SSMIS
IMAGE INDICATED A CLOSED MID-LEVEL EYE FEATURE AND A 1311 UTC ASCAT
OVERPASS REVEALED 39-KT SURFACE WINDS...WHICH WHEN ADJUSTED FOR THE
KNOWN LOW BIAS OF THE SCATTEROMETER DATA YIELDS ABOUT 44 KT. GIVEN
THE MUCH IMPROVED BANDING STRUCTURE SINCE THOSE MICROWAVE DATA WERE
ACQUIRED...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT.
 
GORDON IS NOW MOVING TOWARD THE EAST-NORTHEAST...OR 055/15 KT...AND
IS ON THE PREVIOUS FORECAST TRACK. THE CYCLONE IS MOVING ALONG THE
NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE AND WILL BE MOVING INTO
THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-18 HOURS. GORDON
SHOULD GRADUALLY TURN EASTWARD AND CONTINUE THAT MOTION THROUGH AT
LEAST THE 48-HOUR FORECAST PERIOD. BY 72 HOURS...THE CYCLONE IS
FORECAST TO BEGIN LIFTING OUT TOWARD THE NORTHEAST AHEAD OF A 
SHORTWAVE TROUGH...AND BE NEAR THE AZORES ISLANDS BETWEEN DAYS 3
AND 4. THE NHC TRACK GUIDANCE REMAINS TIGHTLY PACKED AROUND THE
PREVIOUS FORECAST TRACK...SO NO SIGNIFICANT CHANGES WERE MADE TO
THIS FORECAST PACKAGE.
 
UPPER-LEVEL OUTFLOW REMAINS WELL ESTABLISHED IN ALL QUADRANTS...AND
DRY MID-LEVEL AIR HAS MANAGED THUS FAR TO REMAIN AWAY FROM THE
INNER CORE REGION. WEAK VERTICAL SHEAR COUPLED WITH SSTS GREATER
THAN 27C SHOULD ALLOW FOR SOME ADDITIONAL INTENSIFICATION TO OCCUR
DURING THE NEXT 24-36 HOURS. BY 48 HOURS...HOWEVER...ENTRAINMENT OF
DRY MID-LEVEL AIR FROM THE WEST ALONG WITH INCREASING VERTICAL WIND
SHEAR IN EXCESS OF 30 KT SHOULD INDUCE STEADY WEAKENING. AS GORDON
NEARS THE AZORES ISLANDS IN 3 TO 4 DAYS...THE CYCLONE IS FORECAST
BY MOST OF THE GLOBAL MODELS TO MERGE WITH A FRONTAL SYSTEM AND
BECOME A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS
ONLY SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY...AND REMAINS CLOSE
TO IV15 INTENSITY CONSENSUS MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/2100Z 34.2N  52.1W   55 KT  65 MPH
 12H  17/0600Z 34.7N  49.9W   60 KT  70 MPH
 24H  17/1800Z 34.9N  46.2W   65 KT  75 MPH
 36H  18/0600Z 34.7N  42.5W   70 KT  80 MPH
 48H  18/1800Z 34.7N  38.6W   60 KT  70 MPH
 72H  19/1800Z 36.1N  30.8W   55 KT  65 MPH
 96H  20/1800Z 38.8N  23.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  21/1800Z 41.2N  15.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 162154
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   5...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST THU AUG 16 2012
 
...CORRECTED FOR INITIAL MOTION WHICH SHOULD BE 070/15 INSTEAD OF
055/15...

GORDON HAS BEEN STRENGTHENING OVER THE PAST 12 HOURS. VISIBLE
SATELLITE IMAGERY CONTINUES TO SHOW TIGHTLY COILED CONVECTIVE CLOUD
BANDS SPIRALING INTO A SMALL CENTRAL DENSE OVERCAST FEATURE.
SATELLITE INTENSITY ESTIMATES ARE T3.5/55 KT FROM TAFB...T3.0/45 KT
FROM SAB...AND T2.7/39 KT ADT FROM UW-CIMSS. AN 1143 UTC SSMIS
IMAGE INDICATED A CLOSED MID-LEVEL EYE FEATURE AND A 1311 UTC ASCAT
OVERPASS REVEALED 39-KT SURFACE WINDS...WHICH WHEN ADJUSTED FOR THE
KNOWN LOW BIAS OF THE SCATTEROMETER DATA YIELDS ABOUT 44 KT. GIVEN
THE MUCH IMPROVED BANDING STRUCTURE SINCE THOSE MICROWAVE DATA WERE
ACQUIRED...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT.
 
GORDON IS NOW MOVING TOWARD THE EAST-NORTHEAST...OR 070/15 KT...AND
IS ON THE PREVIOUS FORECAST TRACK. THE CYCLONE IS MOVING ALONG THE
NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE AND WILL BE MOVING INTO
THE MID-LATITUDE WESTERLIES DURING THE NEXT 12-18 HOURS. GORDON
SHOULD GRADUALLY TURN EASTWARD AND CONTINUE THAT MOTION THROUGH AT
LEAST THE 48-HOUR FORECAST PERIOD. BY 72 HOURS...THE CYCLONE IS
FORECAST TO BEGIN LIFTING OUT TOWARD THE NORTHEAST AHEAD OF A 
SHORTWAVE TROUGH...AND BE NEAR THE AZORES ISLANDS BETWEEN DAYS 3
AND 4. THE NHC TRACK GUIDANCE REMAINS TIGHTLY PACKED AROUND THE
PREVIOUS FORECAST TRACK...SO NO SIGNIFICANT CHANGES WERE MADE TO
THIS FORECAST PACKAGE.
 
UPPER-LEVEL OUTFLOW REMAINS WELL ESTABLISHED IN ALL QUADRANTS...AND
DRY MID-LEVEL AIR HAS MANAGED THUS FAR TO REMAIN AWAY FROM THE
INNER CORE REGION. WEAK VERTICAL SHEAR COUPLED WITH SSTS GREATER
THAN 27C SHOULD ALLOW FOR SOME ADDITIONAL INTENSIFICATION TO OCCUR
DURING THE NEXT 24-36 HOURS. BY 48 HOURS...HOWEVER...ENTRAINMENT OF
DRY MID-LEVEL AIR FROM THE WEST ALONG WITH INCREASING VERTICAL WIND
SHEAR IN EXCESS OF 30 KT SHOULD INDUCE STEADY WEAKENING. AS GORDON
NEARS THE AZORES ISLANDS IN 3 TO 4 DAYS...THE CYCLONE IS FORECAST
BY MOST OF THE GLOBAL MODELS TO MERGE WITH A FRONTAL SYSTEM AND
BECOME A STRONG EXTRATROPICAL CYCLONE. THE INTENSITY FORECAST IS
ONLY SLIGHTLY HIGHER THAN THE PREVIOUS ADVISORY...AND REMAINS CLOSE
TO IV15 INTENSITY CONSENSUS MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  16/2100Z 34.2N  52.1W   55 KT  65 MPH
 12H  17/0600Z 34.7N  49.9W   60 KT  70 MPH
 24H  17/1800Z 34.9N  46.2W   65 KT  75 MPH
 36H  18/0600Z 34.7N  42.5W   70 KT  80 MPH
 48H  18/1800Z 34.7N  38.6W   60 KT  70 MPH
 72H  19/1800Z 36.1N  30.8W   55 KT  65 MPH
 96H  20/1800Z 38.8N  23.2W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  21/1800Z 41.2N  15.8W   40 KT  45 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 170231
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 PM AST THU AUG 16 2012
 
ALTHOUGH THE CONVECTION IS NOT VERY DEEP...SATELLITE IMAGES SHOW
THAT THE CLOUD PATTERN HAS BECOME SYMMETRIC WITH THE CENTER OF THE
CYCLONE EMBEDDED WITHIN A CIRCULAR AREA OF THE STRONGEST CONVECTION.
A WELL-DEFINED CYCLONICALLY-CURVED BAND IS WRAPPING AROUND THE
NORTH AND EAST SIDES OF THE CIRCULATION. T-NUMBERS FROM BOTH
TAFB AND SAB ARE 4.0 AND 3.0 RESPECTIVELY. AN AVERAGE OF THESE TWO
ESTIMATES SUGGESTS AN INITIAL INTENSITY OF 60 KNOTS. GORDON ONLY
HAS A DAY OR SO TO BECOME A HURRICANE BEFORE IT MOVES OVER COOLER
WATERS AND ENCOUNTERS STRONG SHEAR. A GRADUAL WEAKENING SHOULD THEN
BEGIN...BUT GORDON IS FORECAST TO REMAIN A TROPICAL STORM BY THE
TIME IT MOVES THROUGH THE AZORES IN 3 DAYS. ONCE GORDON MOVE EAST OF
THE AZORES...IT SHOULD ACQUIRE EXTRATROPICAL CHARACTERISTICS.

GORDON IS MOVING TOWARD THE EAST OR 085 DEGREES AT 15 KNOTS...WELL
EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES. SINCE THE STEERING
CURRENTS ARE FORECAST BY THE GLOBAL MODELS TO REMAIN WELL
ESTABLISHED...GORDON SHOULD CONTINUE TO MOVE EASTWARD FOR THE NEXT
THREE DAYS WITH NO SIGNIFICANT CHANGE IN FORWARD SPEED. TRACK
MODELS ARE IN REMARKABLY GOOD AGREEMENT IN BRINGING THE CYCLONE
EASTWARD THROUGH THE AZORES. MODELS ALSO SHOW A GRADUAL TURN TOWARD
THE NORTHEAST BY 72 HOURS AS A SHORTWAVE TROUGH AMPLIFIES TO THE
WEST OF THE CYCLONE. THE OFFICIAL FORECAST IS IN THE MIDDLE OF THE
GUIDANCE ENVELOPE AND BRINGS GORDON THROUGH THE AZORES IN ABOUT 3
DAYS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/0300Z 34.6N  50.3W   60 KT  70 MPH
 12H  17/1200Z 34.9N  47.7W   65 KT  75 MPH
 24H  18/0000Z 34.8N  43.5W   70 KT  80 MPH
 36H  18/1200Z 34.5N  39.5W   65 KT  75 MPH
 48H  19/0000Z 34.5N  35.9W   60 KT  70 MPH
 72H  20/0000Z 36.5N  28.5W   50 KT  60 MPH
 96H  21/0000Z 39.0N  21.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
120H  22/0000Z 41.0N  15.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER AVILA
 

WTNT43 KNHC 170841
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST FRI AUG 17 2012
 
THE CLOUD PATTERN OF GORDON HAS DETERIORATED OVER THE PAST SEVERAL
HOURS WITH CENTRAL CONVECTION BECOMING LESS SYMMETRIC.  MICROWAVE
IMAGES SUGGEST THAT THE LOW-LEVEL CENTER IS LOCATED SOMEWHAT TO THE
SOUTHWEST OF THE MID-LEVEL CIRCULATION...PROBABLY A REFLECTION OF
WESTERLY SHEAR.  SATELLITE ESTIMATES HAVE COME DOWN A BIT...SO THE
INITIAL WIND SPEED IS REDUCED TO 55 KT.  A SMALL TROUGH SEEN TO THE
NORTHWEST OF GORDON IN WATER VAPOR IMAGES COULD HAVE HELPED CAUSED
THE RECENT INCREASE IN SHEAR.  MOST OF THE GLOBAL MODELS SHOW THIS
TROUGH WEAKENING...WHICH MIGHT ALLOW THE SHEAR TO DECREASE AGAIN. 
THE BULK OF THE GUIDANCE STILL PREDICT GORDON WILL BECOME A
HURRICANE BEFORE MOVING OVER COOLER WATERS IN A COUPLE OF
DAYS...THOUGH THE SHIPS AND LGEM MODELS HAVE BACKED OFF ON THIS
SOLUTION.  THE NHC FORECAST IS LOWERED FROM THE PREVIOUS ONE...BUT
STILL SHOWS GORDON BRIEFLY AS A HURRICANE.  THE NEW FORECAST IS
GENERALLY BELOW THE MODEL CONSENSUS...SHADED TOWARD THE SHIPS/LGEM
GUIDANCE.  

GORDON IS MOVING EASTWARD AT ABOUT 16 KT.  THE STORM IS BEING
STEERED TO THE SOUTH OF A LARGE TROUGH OVER THE NORTHEASTERN
ATLANTIC OCEAN...WHICH SHOULD CAUSE THE TROPICAL CYCLONE TO MOVE A
LITTLE SOUTH OF EAST FOR THE NEXT DAY OR SO.  AFTER THAT
TIME...GORDON WILL LIKELY BEGIN TO GAIN SOME LATITUDE AS A
SHORTWAVE MOVES DOWN THE WESTERN SIDE OF THE TROUGH.  MODELS
CONTINUE TO BE IN VERY GOOD AGREEMENT...AND ONLY A SMALL SOUTHWARD
CHANGE WAS MADE TO THE OFFICIAL FORECAST.   WHILE GORDON IS
EXPECTED TO MOVE NEAR THE AZORES IN ABOUT 3 DAYS...A COMBINATION OF
COLD WATER...INCREASING SHEAR...AND A NEARBY BAROCLINIC ZONE SHOULD
PROMOTE EXTRATROPICAL TRANSITION OF THE SYSTEM NEAR OR BEFORE IT
REACHES THOSE ISLANDS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/0900Z 34.6N  48.1W   55 KT  65 MPH
 12H  17/1800Z 34.5N  45.3W   55 KT  65 MPH
 24H  18/0600Z 34.2N  41.4W   60 KT  70 MPH
 36H  18/1800Z 34.2N  37.5W   65 KT  75 MPH
 48H  19/0600Z 34.7N  33.7W   55 KT  65 MPH
 72H  20/0600Z 37.0N  26.0W   50 KT  60 MPH...POST-TROP/EXTRATROP
 96H  21/0600Z 39.0N  19.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  22/0600Z 40.0N  17.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 171440
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 AM AST FRI AUG 17 2012
 
THE SATELLITE APPEARANCE OF GORDON REMAINS RATHER UNIMPRESSIVE...
WITH CLOUD TOP TEMPERATURES WARMING OVER THE PAST FEW HOURS AND THE
COLDEST CLOUD TOPS DISPLACED NORTH AND WEST OF THE CENTER. UW-CIMSS
SATELLITE ANALYSIS AND SHIPS DIAGNOSTICS SHOW AROUND 15 KT OF
WEST-NORTHWESTERLY SHEAR OVER THE CYCLONE...WHILE MET-9 AIRMASS
IMAGERY AND MICROWAVE IMAGERY SHOW SOME DRY AIR WRAPPING INTO THE
CIRCULATION FROM THE SOUTHWEST. THE INITIAL INTENSITY IS HELD AT 55
KT BASED ON A BLEND OF THE LATEST DVORAK FINAL-T AND CI-NUMBERS
FROM TAFB AND SAB. THE CENTRAL PRESSURE OF 997 MB IS BASED ON AN
OBSERVATION OF 999 MB FROM A DRIFTING BUOY THAT THE CENTER PASSED
JUST NORTH OF AROUND 1000 UTC.
 
THE SHEAR IS FORECAST TO DECREASE A LITTLE IN THE SHORT TERM...WHICH
SHOULD ALLOW GORDON TO STRENGTHEN A BIT BEFORE THE CYCLONE REACHES
SUB-26C WATERS AND THE SHEAR INCREASES IN 36 TO 48 HOURS. THE NHC
FORECAST SHOWS THE CYCLONE PEAKING AT 60 KT IN 24 TO 36 HOURS AND
IS CLOSE TO A BLEND OF THE SHIPS AND LGEM MODELS UNTIL
EXTRATROPICAL TRANSITION OCCURS. 
 
THE INITIAL MOTION ESTIMATE IS A LITTLE SOUTH OF DUE EAST...095/16.
GORDON WILL BE STEERED GENERALLY EASTWARD FOR THE NEXT DAY OR SO TO
THE SOUTH OF A LARGE MID/UPPER-LEVEL TROUGH OVER THE NORTHEASTERN
ATLANTIC. BY 48 HOURS...A SHORTWAVE TROUGH IS EXPECTED TO APPROACH
THE CYCLONE FROM THE WEST AND INDUCE AN EAST-NORTHEASTWARD TURN AS
THE CYCLONE BECOMES EXTRATROPICAL IN ABOUT 3 DAYS. A SLOW EAST-
NORTHEASTWARD MOTION IS EXPECTED AT DAYS 4 AND 5 AS THE CYCLONE
WEAKENS. OVERALL THE TRACK MODEL GUIDANCE REMAINS IN GOOD AGREEMENT
ON THIS SCENARIO. THE NEW NHC FORECAST IS LARGELY AN UPDATE OF THE
PREVIOUS ONE AND IS CLOSE TO A CONSENSUS OF THE GFS AND ECMWF.
 
THE 34-KT WIND RADII WERE ADJUSTED OUTWARD BASED ON A PARTIAL ASCAT
PASS FROM AROUND 1250 UTC.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/1500Z 34.5N  46.3W   55 KT  65 MPH
 12H  18/0000Z 34.2N  43.4W   55 KT  65 MPH
 24H  18/1200Z 34.1N  39.6W   60 KT  70 MPH
 36H  19/0000Z 34.4N  35.6W   60 KT  70 MPH
 48H  19/1200Z 35.2N  31.8W   55 KT  65 MPH
 72H  20/1200Z 38.0N  24.0W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  21/1200Z 39.0N  19.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
120H  22/1200Z 39.5N  16.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BRENNAN
 

WTNT43 KNHC 172051
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST FRI AUG 17 2012
 
THE SATELLITE PRESENTATION OF GORDON HAS IMPROVED SINCE THE LAST
ADVISORY.  THE CENTER OF CIRCULATION IS NOW EMBEDDED BENEATH A
CENTRAL DENSE OVERCAST WITH A BAND OF CONVECTION CURLING AROUND TO
THE EAST.  DVORAK ESTIMATES HAVE INCREASED FROM THIS MORNING...AND
THEY ARE NOW MORE SUPPORTIVE OF THE 55-KT INITIAL INTENSITY.  THE
WIND RADII HAVE BEEN INCREASED A BIT BASED ON AMSU DATA FROM
EARLIER IN THE DAY.
 
GORDON IS FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES...MOVING
EASTWARD WITH A MOTION OF 095/17 KT.  THE CYCLONE IS EXPECTED TO
CONTINUE MOVING QUICKLY EASTWARD THROUGH 72 HOURS AS IT MOVES INTO
THE BASE OF AN AMPLIFIED TROUGH OVER THE NORTHEASTERN ATLANTIC. 
AFTER THAT...GORDON SHOULD BE A WEAKER CYCLONE...AND IT WILL LIKELY
TURN EAST-SOUTHEASTWARD BY DAY 5 AS IT BECOMES STEERED BY
LOWER-LEVEL NORTHERLY FLOW.  THE TRACK GUIDANCE IS TIGHTLY
CLUSTERED THROUGH MUCH OF THE FORECAST PERIOD...ESPECIALLY WITHIN
THE FIRST 72 HOURS AS THE CYCLONE APPROACHES THE AZORES.  THE
OFFICIAL NHC TRACK FORECAST LIES BETWEEN THE GFS AND ECMWF
SOLUTIONS AND IS A LITTLE FASTER THAN THE HFIP MULTI-MODEL
CONSENSUS TV15.
 
THE VERTICAL SHEAR IS NOT EXPECTED TO BE TOO DETRIMENTAL FOR SOME
STRENGTHENING WHILE GORDON REMAINS OVER WATERS WARMER THAN 26C FOR
THE NEXT 36 HOURS OR SO.  THE DEEP-LAYER SHEAR IS EXPECTED TO
INCREASE ABOVE 30 KT BY 48 HOURS...AND WEAKENING SHOULD HAVE
COMMENCED BY THAT TIME.  GORDON SHOULD THEN COMPLETE EXTRATROPICAL
TRANSITION IN ABOUT 72 HOURS...AFTER IT HAS ALREADY PASSED THE
AZORES.  THERE IS SOME UNCERTAINTY IN THE INTENSITY FORECAST DURING
THE FIRST 48 HOURS...WITH MANY OF THE DYNAMICAL MODELS MAKING
GORDON A HURRICANE WHILE THE STATISTICAL SHIPS AND LGEM MODELS SHOW
VERY LITTLE STRENGTHENING.  THE OFFICIAL INTENSITY FORECAST BRINGS
GORDON JUST BELOW HURRICANE STRENGTH...BUT IT WOULD NOT BE
SURPRISING IF IT DID BECOME A HURRICANE DURING THE NEXT DAY OR SO.
IN FACT...BASED ON PAST NHC INTENSITY ERRORS...THERE IS A 1 IN 3
CHANCE THAT GORDON COULD BE A HURRICANE AT THE 24- AND 36-HOUR
FORECAST PERIODS.
 
BASED ON THE NEW FORECAST...GORDON WILL BE APPROACHING THE AZORES AS
A TROPICAL CYCLONE IN 48 HOURS.  THE GOVERNMENT OF PORTUGAL HAS
THEREFORE ISSUED A TROPICAL STORM WATCH FOR THE CENTRAL AND EASTERN
AZORES.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/2100Z 34.3N  44.0W   55 KT  65 MPH
 12H  18/0600Z 34.1N  41.2W   55 KT  65 MPH
 24H  18/1800Z 34.2N  37.3W   60 KT  70 MPH
 36H  19/0600Z 34.7N  33.0W   60 KT  70 MPH
 48H  19/1800Z 35.8N  28.9W   55 KT  65 MPH
 72H  20/1800Z 38.5N  21.5W   45 KT  50 MPH...POST-TROP/EXTRATROP
 96H  21/1800Z 39.5N  17.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  22/1800Z 38.5N  14.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER BERG/AVILA
 

WTNT43 KNHC 180233
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 PM AST FRI AUG 17 2012
 
A SERIES OF SSMIS MICROWAVE OVERPASSES FROM THE NAVY/NRL TC PAGE
INDICATE THAT DEEP CONVECTIVE BANDING HAS DEVELOPED OVER THE
SOUTHERN HALF OF GORDON.  BASED ON THE IMPROVED CLOUD PATTERN...THE
TAFB SATELLITE INTENSITY ESTIMATE...AND TWO EARLIER CIRA AMSU-A
ESTIMATES OF 62 AND 70 KT...THE INITIAL INTENSITY IS INCREASED TO
60 KT.

THE OCEAN IS WARM AND THE SHEAR IS RELATIVELY LOW...FOR AT LEAST THE
NEXT 24 HOURS.  SUBSEQUENTLY...GORDON COULD STILL BECOME A
HURRICANE IN THE SHORT TERM ALTHOUGH THE INTENSITY FORECAST DOES
NOT EXPLICITLY INDICATE STRENGTHENING.  VERTICAL SHEAR IS FORECAST
TO INCREASE SIGNIFICANTLY BY DAY 2 WHICH SHOULD INDUCE A WEAKENING
TREND.  GORDON SHOULD COMPLETE EXTRATROPICAL TRANSITION AROUND THE
72 HOUR PERIOD...AS INDICATED BY A MAJORITY OF THE GLOBAL MODELS
AND THE FLORIDA STATE CYCLONE PHASE EVOLUTION DIAGRAM.  THE NHC
INTENSITY FORECAST IS BASED ON THE IVCN STATISTICAL-DYNAMICAL
INTENSITY MODEL CONSENSUS AND REFLECTS DISSIPATION AT DAY 5.
 
THE INITIAL MOTION IS ESTIMATED TO BE 090/16 KT...WITHIN THE MID- TO
UPPER-LEVEL MID-LATITUDE WESTERLIES.  GORDON SHOULD CONTINUE MOVING
GENERALLY EASTWARD AT A RAPID CLIP THROUGH DAY 3 AS IT MOVES SOUTH
OF A LARGER EXTRATROPICAL LOW SITUATED A FEW HUNDRED MILES WEST OF
THE UNITED KINGDOM.  THROUGH THE REMAINDER OF THE FORECAST
PERIOD...GORDON SHOULD BE A WEAK POST-TROPICAL CYCLONE...AND IS
EXPECTED TO DECREASE IN FORWARD SPEED BY DAY 5 IN RESPONSE TO THE
LOW-LEVEL NORTHERLY FLOW PRODUCED BY HIGH PRESSURE TO THE WEST. 
THE OFFICIAL TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ADVISORY
AND THE TVCA MULTI-MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0300Z 34.2N  42.1W   60 KT  70 MPH
 12H  18/1200Z 34.1N  39.3W   60 KT  70 MPH
 24H  19/0000Z 34.4N  35.3W   60 KT  70 MPH
 36H  19/1200Z 35.2N  31.3W   55 KT  65 MPH
 48H  20/0000Z 36.4N  27.4W   50 KT  60 MPH
 72H  21/0000Z 39.0N  20.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
 96H  22/0000Z 39.0N  16.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
120H  23/0000Z...DISSIPATED
 
$$
FORECASTER ROBERTS
 

WTNT43 KNHC 180905
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST SAT AUG 18 2012
 
GORDON HAS BECOME BETTER ORGANIZED DURING THE PAST FEW HOURS.
CONVECTION HAS WRAPPED ALL THE WAY AROUND THE CENTER...AND
RECENT TRMM AND SSM/I OVERPASSES SHOWED AN EYE HAS DEVELOPED.
SATELLITE INTENSITY ESTIMATES FROM TAFB AND SAB WERE 55 KT AT 0600
UTC...AND AN AMSU ESTIMATE FROM CIMSS AT 0454 UTC WAS 64 KT.  BASED
ON THESE DATA AND THE SUBSEQUENT INCREASE IN ORGANIZATION...GORDON
IS UPGRADED TO A HURRICANE.
 
THE INITIAL MOTION IS 090/16.  A LARGE DEEP-LAYER LOW CENTERED WEST
OF THE BRITISH ISLES SHOULD STEER GORDON EASTWARD TO EAST-
NORTHEASTWARD FOR THE NEXT 48-72 HR.  AFTER THAT...A SLOWER MOTION
TOWARD THE EAST IS EXPECTED AS THE LOW LIFTS OUT TO THE NORTHEAST
AND A LOW-LEVEL RIDGE BUILDS TO THE NORTH AND NORTHWEST OF GORDON.
THE NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK AND LIES
NEAR THE CENTER OF THE TRACK GUIDANCE ENVELOPE.
 
THE VERTICAL WIND SHEAR IS CURRENTLY LIGHT AND THE SEA SURFACE
TEMPERATURES ARE RELATIVELY WARM...FAVORABLE CONDITIONS FOR
STRENGTHENING OR AT LEAST MAINTAINING THE CURRENT INTENSITY FOR THE
NEXT 12-18 HR.  THE NEW INTENSITY FORECAST THUS CALLS FOR GORDON TO
REMAIN A HURRICANE TODAY.  AFTER THAT...INCREASING SHEAR...
DECREASING SSTS...AND THE ONSET OF EXTRATROPICAL TRANSITION SHOULD
CAUSE A STEADY WEAKENING.  GORDON IS FORECAST TO BECOME
EXTRATROPICAL BY 72 HR AND DISSIPATE COMPLETELY BY 120 HR IN
AGREEMENT WITH THE GLOBAL MODEL GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0900Z 34.0N  40.7W   65 KT  75 MPH
 12H  18/1800Z 34.0N  37.7W   65 KT  75 MPH
 24H  19/0600Z 34.5N  33.7W   60 KT  70 MPH
 36H  19/1800Z 35.3N  29.9W   55 KT  65 MPH
 48H  20/0600Z 36.5N  26.5W   50 KT  60 MPH
 72H  21/0600Z 38.5N  20.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  22/0600Z 38.5N  16.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  23/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 181436
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 AM AST SAT AUG 18 2012
 
GORDON HAS CONTINUED TO STRENGTHEN THIS MORNING. THE EYE HAS BECOME
A LITTLE MORE APPARENT IN GEOSTATIONARY IMAGERY OVER THE PAST FEW
HOURS...AND IS QUITE DISTINCT IN RECENT MICROWAVE IMAGES. THE
INITIAL INTENSITY IS SET TO 70 KT BASED ON A BLEND OF THE LATEST
DVORAK ESTIMATES FROM TAFB AND SAB. THERE IS STILL TIME FOR GORDON
TO STRENGTHEN A BIT MORE BEFORE THE CYCLONE REACHES COOLER
WATERS IN ABOUT 24 HOURS...SO THE OFFICIAL FORECAT HAS BEEN
ADJUSTED UPWARD TO ACCOUNT FOR THAT POSSIBILITY AND THE OBSERVED
INTENSIFICATION. SOUTHWESTERLY SHEAR IS EXPECTED TO INCREASE
MARKEDLY BY 24 TO 36 HOURS AS A SHORTWAVE TROUGH APPROACHES THE
CYCLONE FROM THE NORTHWEST. THE INCREASED SHEAR COMBINED WITH
COOLER SSTS SHOULD RESULT IN STEADY WEAKENING. GLOBAL MODEL FIELDS
SHOW GORDON BECOMING EXTRATROPICAL BY 72 HOURS AND DISSIPATING BY
THE END OF THE PERIOD.
 
THE INITIAL MOTION ESTIMATE IS 090/16...AS GORDON IS BEING STEERED
EASTWARD BY A DEEP LAYER CYCLONE WEST OF THE BRITISH ISLES. A TURN
TOWARD THE EAST-NORTHEAST IS EXPECTED ON SUNDAY AS THE SHORTWAVE
TROUGH APPROACHES GORDON AND THE LARGER DEEP-LAYER LOW LIFTS
NORTHWARD. OVERALL THE TRACK MODEL GUIDANCE IS FASTER THIS CYCLE...
AND THE NHC FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION. THE NEW
NHC TRACK IS CLOSE TO THE LATEST MULTI-MODEL CONSENSUS AND LIES
BETWEEN THE ECMWF AND GFS MODELS.

GIVEN THE NEW INTENSITY AND TRACK FORECAST...THE GOVERNMENT OF
PORTUGAL HAS ISSUED A HURRICANE WARNING FOR THE CENTRAL AND EASTERN
AZORES AT THIS TIME. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/1500Z 34.1N  38.6W   70 KT  80 MPH
 12H  19/0000Z 34.3N  35.5W   75 KT  85 MPH
 24H  19/1200Z 35.0N  31.4W   70 KT  80 MPH
 36H  20/0000Z 36.1N  27.8W   65 KT  75 MPH
 48H  20/1200Z 37.4N  24.6W   55 KT  65 MPH
 72H  21/1200Z 38.5N  20.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  22/1200Z 38.5N  16.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  23/1200Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

WTNT43 KNHC 182032
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST SAT AUG 18 2012
 
THE INTENSIFICATION OF GORDON HAS CONTINUED OVER THE PAST FEW
HOURS...AS THE EYE HAS CLEARED AND WARMED AND CLOUD TOPS HAVE
COOLED AROUND THE CENTER. DVORAK ESTIMATES WERE T5.0 FROM TAFB AND
SAB AT 1800 UTC...AND THE INITIAL INTENSITY IS 90 KT FOR THIS
ADVISORY. GORDON SHOULD BE NEAR ITS PEAK INTENSITY AS THE CYCLONE
WILL BE CROSSING THE 26C ISOTHERM IN THE NEXT 12 HOURS...AND STEADY
WEAKENING IS EXPECTED TO BEGIN AFTER THAT TIME. THE NEW NHC
INTENSITY FORECAST HAS BEEN ADJUSTED UPWARD DUE TO THE STRONGER
INITIAL INTENSITY AND IS CLOSE TO THE DECAY SHIPS MODEL THROUGH 48
HOURS. A SHORTWAVE TROUGH WILL BEGIN TO INTERACT WITH GORDON IN 36
TO 48 HOURS AND THE CYCLONE SHOULD BE EXTRATROPICAL BY 72 HOURS IF
NOT A LITTLE SOONER. RAPID WEAKENING IS EXPECTED AFTER 48 HOURS AS
THE SHEAR INCREASES MARKEDLY AND THE GLOBAL MODELS SHOW THE LOW AND
MID-LEVEL CIRCULATIONS DECOUPLING. THE CYCLONE IS EXPECTED TO
DISSIPATE BY THE END OF THE FORECAST PERIOD. 

THE INITIAL MOTION ESTIMATE IS 085/18...A LITTLE FASTER THAN THE
PREVIOUS ESTIMATE...AS THE DEEP-LAYER CLOSED LOW CENTERED NEAR
50N/20W STEERS GORDON QUICKLY EASTWARD. DURING THE NEXT COUPLE OF
DAYS THE CLOSED LOW LIFTS NORTH AND THE AFOREMENTIONED SHORTWAVE
TROUGH WILL TUG GORDON EAST-NORTHEASTWARD AND NORTHEASTWARD. AFTER
THE LOW-LEVEL CIRCULATION DECOUPLES...A SLOWER EASTWARD MOTION IS
EXPECTED THROUGH DISSIPATION. THE GUIDANCE CONTINUES TO TREND
FASTER...AND THE NEW NHC FORECAST FOLLOWS SUIT AND IS CLOSE TO THE 
ECMWF MODEL THROUGH DISSIPATION. 

FORECAST POSITIONS AND MAX WINDS
 
INIT  18/2100Z 34.1N  36.4W   90 KT 105 MPH
 12H  19/0600Z 34.4N  33.2W   90 KT 105 MPH
 24H  19/1800Z 35.4N  29.2W   80 KT  90 MPH
 36H  20/0600Z 36.8N  25.5W   70 KT  80 MPH
 48H  20/1800Z 38.0N  22.8W   60 KT  70 MPH
 72H  21/1800Z 39.0N  19.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  22/1800Z 39.0N  16.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
120H  23/1800Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

WTNT43 KNHC 190233
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 PM AST SAT AUG 18 2012
 
GORDON HAS AN IMPRESSIVE SATELLITE PRESENTATION WITH A DISTINCT WARM
EYE. A BLEND OF THE SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES
YIELDS AN INITIAL WIND SPEED OF 95 KT. THE HURRICANE IS CROSSING
THE 26C ISOTHERM AND SHOULD BEGIN TO LOSE STRENGTH SOON. WEAKENING
SHOULD BE MORE RAPID BY LATE TOMORROW AS THE CYCLONE MOVES OVER
COOL WATERS AND IN A HIGH SHEAR ENVIRONMENT...ALTHOUGH EVERY MODEL
KEEPS GORDON AS A HURRICANE AS IT PASSES THE AZORES. THE NHC
INTENSITY FORECAST IS CLOSE TO THE PREVIOUS ONE AND THE LGEM MODEL.
A STRONG TROUGH WILL BEGIN TO INTERACT WITH GORDON IN A COUPLE OF
DAYS...WHICH SHOULD FACILITATE EXTRATROPICAL TRANSITION BY 72
HOURS.
 
THE INITIAL MOTION ESTIMATE IS 080/19...A LITTLE FASTER THAN THE
PREVIOUS ESTIMATE. THE CYCLONE SHOULD TURN MORE TO THE EAST-
NORTHEAST OR NORTHEAST WITHIN A DAY OR SO DUE TO AN APPROACHING
SHORTWAVE TROUGH. THE LATEST GUIDANCE IS WELL-CLUSTERED WITH ALMOST
EVERY MODEL MOVING GORDON THROUGH THE EASTERN AZORES BETWEEN 24 AND
36 HOURS. THE NEW NHC FORECAST IS BASICALLY AN UPDATE OF THE
PREVIOUS ONE...STAYING ON THE SPEEDY SIDE OF THE GUIDANCE SINCE
GORDON HAS BEEN A FAST MOVER.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0300Z 34.5N  33.9W   95 KT 110 MPH
 12H  19/1200Z 35.1N  30.7W   90 KT 105 MPH
 24H  20/0000Z 36.3N  26.9W   75 KT  85 MPH
 36H  20/1200Z 37.7N  23.6W   65 KT  75 MPH
 48H  21/0000Z 38.9N  20.8W   55 KT  65 MPH
 72H  22/0000Z 39.5N  17.5W   35 KT  40 MPH...POST-TROP/EXTRATROP
 96H  23/0000Z 39.0N  15.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
120H  24/0000Z...DISSIPATED
 
$$
FORECASTER BLAKE
 

WTNT43 KNHC 190846
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST SUN AUG 19 2012
 
GORDON REMAINS A WELL ORGANIZED HURRICANE BUT IT APPEARS TO HAVE
WEAKENED A LITTLE. THE LATEST DVORAK CLASSIFICATIONS FROM
TAFB...SAB...AND UW-CIMSS HAVE FALLEN SLIGHTLY FROM THE PREVIOUS
VALUES LIKELY DUE TO A SLIGHT COOLING OF THE EYE AND A THINNING OF
THE CONVECTIVE CLOUDS ON THE SOUTH SIDE OF THE CIRCULATION. THE
INITIAL WIND SPEED IS ESTIMATED TO BE 90 KT...IN AGREEMENT WITH THE
SATELLITE INTENSITY ESTIMATES. THE HURRICANE HAS NOW MOVED OVER
SUB-26C WATERS AND CURRENTLY LIES IN AN ENVIRONMENT OF MODERATE
WESTERLY SHEAR. SINCE THE SEA SURFACE TEMPERATURES DECREASE
FURTHER ON THE EXPECTED TRACK AND BECAUSE GORDON IS ANTICIPATED TO
MOVE INTO EVEN STRONGER SHEAR...STEADY WEAKENING IS FORECAST.
POST-TROPICAL TRANSITION IS ANTICIPATED TO OCCUR IN 2 TO 3
DAYS...WHEN THE VERTICAL CIRCULATION IS EXPECTED TO BECOME
SIGNIFICANTLY DECOUPLED. THE OFFICIAL FORECAST SHOWS THE
POST-TROPICAL CYCLONE DISSIPATING BY DAY 4...FOLLOWING THE GLOBAL
MODEL GUIDANCE.
 
GORDON CONTINUES TO MOVE SWIFTLY EASTWARD AT ABOUT 20 KT. A SHORT
WAVE TROUGH SEEN IN WATER VAPOR IMAGES NEAR 40N/40W IS SWINGING
SOUTHEASTWARD TOWARD THE HURRICANE. THIS FEATURE SHOULD CAUSE THE
CYCLONE TO TURN EAST-NORTHEASTWARD...TAKING GORDON VERY NEAR SANTA
MARIA AND SAO MIGUEL ISLANDS IN THE EASTERN AZORES IN 18 TO 24
HOURS.  AFTER PASSING THE AZORES...THE WEAKENING CYCLONE IS
FORECAST TO SLOW DOWN SUBSTANTIALLY AND TURN BACK TO THE EAST
BEFORE IT DISSIPATES. THE TRACK MODEL GUIDANCE REMAINS TIGHTLY
CLUSTERED...AND THE OFFICIAL FORECAST LIES VERY NEAR THE
MULTI-MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0900Z 34.9N  31.6W   90 KT 105 MPH
 12H  19/1800Z 35.7N  28.6W   80 KT  90 MPH
 24H  20/0600Z 37.2N  25.0W   70 KT  80 MPH
 36H  20/1800Z 38.6N  22.0W   60 KT  70 MPH
 48H  21/0600Z 39.4N  19.4W   50 KT  60 MPH
 72H  22/0600Z 39.7N  16.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  23/0600Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI/BROWN
 

WTNT43 KNHC 191438
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 AM AST SUN AUG 19 2012
 
THE EYE OF GORDON IS INTERMITTENTLY VISIBLE IN GEOSTATIONARY
IMAGERY...BUT HAS BEGUN TO SHRINK AND BECOME LESS DISTINCT OVER THE
PAST FEW HOURS. AN 1103 UTC SSMIS PASS FROM THE FNMOC TC WEBPAGE
SHOWS THAT THE EYEWALL HAS OPENED UP ON THE SOUTH SIDE. THE
CIRCULATION ALSO APPEARS TO BE TILTING EASTWARD WITH HEIGHT...
LIKELY DUE TO THE ALMOST 30 KT OF SHEAR ANALYZED OVER GORDON BY
UW-CIMSS. THE INITIAL INTENSITY HAS BEEN LOWERED TO 85 KT FOR THIS
ADVISORY BASED ON A BLEND OF THE LATEST DVORAK ESTIMATES FROM TAFB
AND SAB...AND THIS COULD BE A LITTLE GENEROUS. STEADY WEAKENING IS
FORECAST SINCE GORDON WILL BE MOVING OVER COOLER SSTS WHILE THE
SHEAR REMAINS ABOVE 30 KT AS A SHORTWAVE TROUGH CURRENTLY NEAR
40N/40W OVERTAKES THE TROPICAL CYCLONE IN THE NEXT 36 HOURS. THE
NHC INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD AND IS BETWEEN
THE LATEST DECAY SHIPS AND LGEM MODELS...BUT KEEPS GORDON AS A
HURRICANE AS IT PASSES NEAR THE EASTERN AZORES TOMORROW. THE GFS
AND ECMWF GLOBAL MODELS SHOW THE LOW- AND MID-LEVEL CIRCULATIONS OF
GORDON DECOPULING BY 48 HOURS...AND THE CYCLONE SHOULD BECOME
POST-TROPICAL AROUND THAT TIME. GORDON SHOULD BECOME A REMNANT LOW
BY 72 HOURS WITH DISSIPATION EXPECTED BY DAY 4.

THE INITIAL MOTION ESTIMATE IS 075/18. GORDON SHOULD CONTINUE
EAST-NORTHEASTWARD WITH A GRADUAL DECREASE IN FORWARD SPEED OVER
THE NEXT 48 HOURS AS THE CYCLONE INTERACTS WITH THE AFOREMENTIONED
SHORTWAVE. BEYOND THAT TIME A SLOWER EASTWARD MOTION IS EXPECTED
AFTER THE CIRCULATION DECOUPLES. THE TRACK MODEL GUIDANCE REMAINS
IN GOOD AGREEMENT ON THIS SCENARIO...AND THE NEW NHC FORECAST IS AN
UPDATE OF THE PREVIOUS ONE THROUGH 36 HOURS. AT 48 AND 72 HOURS THE
NHC TRACK IS A BIT SLOWER...TRENDING TOWARD THE MULTI-MODEL
CONSENSUS AIDS AND THE ECMWF. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/1500Z 35.5N  29.7W   85 KT 100 MPH
 12H  20/0000Z 36.5N  26.8W   75 KT  85 MPH
 24H  20/1200Z 38.0N  23.6W   60 KT  70 MPH
 36H  21/0000Z 39.2N  20.8W   50 KT  60 MPH
 48H  21/1200Z 39.5N  19.0W   40 KT  45 MPH...POST-TROPICAL
 72H  22/1200Z 39.5N  17.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 96H  23/1200Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

WTNT43 KNHC 192034
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 PM AST SUN AUG 19 2012
 
GORDON CONTINUES TO SLOWLY WEAKEN...AS DEEP CONVECTION IS ERODING
SOUTH OF THE CENTER AND THE OVERALL CLOUD PATTERN HAS BECOME
ELONGATED.  HOWEVER...THE EYE HAS STILL BEEN APPARENT ON RECENT
INFRARED IMAGERY.  THE INITIAL INTENSITY IS 75 KT BASED ON THE
LATEST DVORAK CI-NUMBERS FROM TAFB AND SAB.  STEADY WEAKENING IS
EXPECTED TO CONTINUE DUE TO COOL WATERS AND STRONG SHEAR...AND  THE
NEW NHC INTENSITY FORECAST HAS BEEN ADJUSTED DOWNWARD IN AGREEMENT
WITH THE LATEST SHIPS AND LGEM GUIDANCE.  MODEL FIELDS AND FSU
PHASE SPACE DIGRAMS SUGGEST THAT GORDON WILL BE POST-TROPICAL BY 36
HOURS...AND THE CYCLONE SHOULD THEN SHEAR APART AND BECOME A
REMNANT LOW BY 72 HOURS.  DISSIPATION IS EXPECTED BY 96 HOURS...IF
NOT SOONER.
 
THE INITIAL MOTION ESTIMATE IS 070/18.  THE TRACK GUIDANCE CONTINUES
TO BE IN GOOD AGREEMENT ON THE SCENARIO OF GORDON INTERACTING WITH
A SHORTWAVE TROUGH APPROACHING FROM THE WEST-NORTHWEST...WHICH
SHOULD INDUCE A BIT MORE OF A POLEWARD COMPONENT OF MOTION AND A
DECREASE IN FORWARD SPEED IN THE NEXT DAY OR SO.  AFTER 36
HOURS...AS THE LOW-LEVEL CENTER DECOUPLES...A SLOW EASTWARD DRIFT
IS EXPECTED THROUGH DISSIPATION.  THE NEW NHC TRACK FORECAST IS
CLOSE TO THE PREVIOUS ONE AND THE NEW MULTI-MODEL CONSENSUS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/2100Z 36.1N  27.5W   75 KT  85 MPH
 12H  20/0600Z 37.3N  24.9W   60 KT  70 MPH
 24H  20/1800Z 38.8N  21.8W   50 KT  60 MPH
 36H  21/0600Z 39.2N  19.2W   40 KT  45 MPH...POST-TROPICAL
 48H  21/1800Z 39.2N  18.2W   35 KT  40 MPH...POST-TROPICAL
 72H  22/1800Z 39.0N  17.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  23/1800Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

WTNT43 KNHC 200243
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  18
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 PM AST SUN AUG 19 2012
 
THE EYE DISAPPEARED ON SATELLITE IMAGERY SEVERAL HOURS AGO AND THE
CLOUD PATTERN IS BECOMING INCREASINGLY RAGGED.  A RECENT ASCAT PASS
OVER THE HURRICANE SHOWED THAT THE CENTER IS LOCATED IN THE
SOUTHWEST PART OF THE CLOUD MASS...BUT THAT THE CIRCULATION IS
STILL QUITE STRONG.  THE CURRENT INTENSITY ESTIMATE OF 70 KT IS
BASED ON AN ASSUMED SLOW WEAKENING RATE AND IS CONSISTENT WITH A
BLEND OF T- AND CI-NUMBERS FROM TAFB AND SAB.   THE COMBINATION OF
INCREASED SOUTHWESTERLY SHEAR AND COOLER WATERS SHOULD LEAD TO
STEADY WEAKENING.  GORDON IS LIKELY TO BECOME A POST-TROPICAL
CYCLONE IN 24-36 HOURS AND THE CYCLONE SHOULD DISSIPATE IN 72
HOURS OR LESS.   THE OFFICIAL INTENSITY FORECAST IS CLOSE TO THE
LATEST SHIPS OUTPUT...BUT IS IS WORTH NOTING THAT THE DIAGNOSTICS
FROM THAT MODEL SHOW GORDON LOSING TROPICAL CHARACTERISTICS ON
MONDAY.

NOW THAT THE CENTER HAS MORE BECOME DIFFICULT TO FIND...THE INITIAL
MOTION IS A RATHER UNCERTAIN 070/17...OR PERHAPS A LITTLE SLOWER.
THE HURRICANE CONTINUES TO BE EMBEDDED IN A WESTERLY CURRENT TO
THE SOUTH OF A LARGE LOW OVER THE NORTHEASTERN ATLANTIC.  AS THE
UPPER-LEVEL CIRCULATION OF GORDON IS LIKELY TO BE SHEARED AWAY BY
STRONG UPPER-LEVEL WINDS IN ABOUT 36 HOURS...GORDON OR ITS
POST-TROPICAL COUNTERPART SHOULD BECOME A SHALLOW CYCLONE STEERED
MAINLY BY THE WEAKER LOW-LEVEL FLOW.  THEREFORE A CONSIDERABLE
SLOWING OF THE FORWARD SPEED IS ANTICIPATED.  THE OFFICIAL TRACK
FORECAST IS CLOSE TO THE DYNAMICAL MODEL CONSENSUS BUT A BIT FASTER
THAN THE LATEST GFS TRACK.
 
THE INITIAL AND FORECAST WIND RADII HAVE BEEN ADJUSTED BASED ON THE
TIMELY ASCAT PASS. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0300Z 36.7N  25.8W   70 KT  80 MPH
 12H  20/1200Z 37.8N  23.3W   55 KT  65 MPH
 24H  21/0000Z 38.8N  20.8W   45 KT  50 MPH
 36H  21/1200Z 39.2N  19.3W   35 KT  40 MPH...POST-TROPICAL
 48H  22/0000Z 39.3N  18.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
 72H  23/0000Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT43 KNHC 200833
TCDAT3
 
HURRICANE GORDON DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
500 AM AST MON AUG 20 2012
 
SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE THE CENTER OF
THE EYE OF HURRICANE GORDON PASSED OVER SANTA MARIA ISLAND IN THE
EASTERN AZORES AROUND 0530 UTC. SINCE THAT TIME...HOWEVER...THE
CLOUD PATTERN OF THE CYCLONE HAS BECOME RAGGED AND SHEARED TO THE 
NORTHEAST OF THE EXPOSED LOW-LEVEL EYE FEATURE. THE INITIAL
INTENSITY OF 65 KT IS BASED ON A CONSENSUS SATELLITE CI-NUMBER OF
T4.0/65 KT FROM TAFB...SAB...AND UW-CIMSS ADT...WHICH COULD BE
GENEROUS.

THE INITIAL MOTION ESTIMATE IS NOW 060/13. GORDON IS ON TRACK SO
THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR
REASONING. GORDON WILL GRADUALLY MOVE AWAY FROM THE AZORES ISLANDS
TODAY...AND CONTINUE TO SLOW DOWN AND TURN TOWARD THE EAST OVER THE
NEXT 48 HOURS AS THE CYCLONE WEAKENS AND BECOMES MORE VERTICALLY
SHALLOW DUE TO STRONG SOUTHWESTERLY VERTICAL WIND SHEAR AND COLDER
WATERS. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS
TRACK AND IS CLOSE TO THE CONSENSUS MODELS TV15 AND TVCA.

SURFACE OBSERVATIONS FROM THE AZORES INDICATE AMBIENT AND DEWPOINT
TEMPERATURES ARE RUNNING 19-21C...WHICH IS NOT VERY TROPICAL-LIKE.
ALSO...VERTICAL SHEAR HAS INCREASED TO MORE THAN 30 KT AND IT IS
EXPECTED TO REMAIN ABOVE THAT VALUE FOR THE NEXT SEVERAL DAYS. AS A
RESULT OF THESE VERY UNFAVORABLE DYNAMIC AND THERMODYNAMIC
CONDITIONS...GORDON IS EXPECTED TO TRANSITION INTO A POST-TROPICAL
EXTRATROPICAL CYCLONE WITHIN THE NEXT 12-24 HOURS...AND DISSIPATE
OVER THE COLD ATLANTIC WATERS BETWEEN THE AZORES AND PORTUGAL BY 72
HOURS. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS
ADVISORY AND CLOSELY FOLLOWS THE DECAY-SHIPS INTENSITY MODEL.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0900Z 37.4N  24.3W   65 KT  75 MPH
 12H  20/1800Z 38.3N  22.1W   55 KT  65 MPH...POST-TROP/EXTRATROP
 24H  21/0600Z 38.9N  20.1W   45 KT  50 MPH...POST-TROP/EXTRATROP
 36H  21/1800Z 39.2N  18.7W   35 KT  40 MPH...POST-TROP/EXTRATROP
 48H  22/0600Z 39.2N  17.3W   30 KT  35 MPH...POST-TROP/EXTRATROP
 72H  23/0600Z...DISSIPATED
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 201441
TCDAT3
 
TROPICAL STORM GORDON DISCUSSION NUMBER  20
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL082012
1100 AM AST MON AUG 20 2012
 
THE INSTITUTE OF METEOROLOGY IN THE AZORES PROVIDED A REPORT OF A
MINIMUM PRESSURE OF 980 MB ON SANTA MARIA ISLAND IN THE EASTERN
AZORES AS GORDON PASSED OVER THAT ISLAND THIS MORNING. A MAXIMUM
10-MINUTE WIND OF 53 KT WITH A GUST TO 70 KT WAS OBSERVED AT SANTA
MARIA AIRPORT. SINCE PASSING THE EASTERN AZORES...GORDON HAS
CONTINUED TO LOSE ORGANIZATION...AND THE CENTER IS INCREASINGLY
EXPOSED TO THE SOUTH OF THE DEEP CONVECTION DUE TO STRONG
SOUTHWESTERLY SHEAR. THE INITIAL WIND SPEED IS REDUCED TO 55 KT...
AND IS BASED ON RECENT DVORAK CLASSIFICATIONS AND A PARTIAL ASCAT
PASS FROM SHORTLY BEFORE 1200 UTC. GORDON SHOULD CONTINUE TO
STEADILY WEAKEN DUE TO THE STRONG SHEAR...COOL WATERS...AND
UNFAVORABLE THERMODYNAMIC CONDITIONS. GORDON IS FORECAST TO BECOME
POST-TROPICAL WITHIN 12 HOURS AND DISSIPATE IN A COUPLE OF DAYS.
 
THE INITIAL MOTION IS EAST-NORTHEASTWARD OR 060 DEGREES AT 14 KT.
GORDON IS EXPECTED TO SLOW DOWN AND TURN EASTWARD AS THE CYCLONE
WEAKENS AND BECOMES A SHALLOW SYSTEM. THE OFFICIAL FORECAST IS
SIMILAR TO THE PREVIOUS ADVISORY AND IS BETWEEN THE GFS AND ECMWF
SOLUTIONS.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/1500Z 38.3N  22.3W   55 KT  65 MPH
 12H  21/0000Z 39.0N  20.3W   40 KT  45 MPH...POST-TROPICAL
 24H  21/1200Z 39.2N  18.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 36H  22/0000Z 39.2N  17.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  22/1200Z 39.0N  16.7W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  23/1200Z...DISSIPATED
 
$$
FORECASTER BROWN
 

