WTNT42 KNHC 180238
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 PM EDT SUN JUL 17 2011
 
THE AIR FORCE HURRICANE HUNTER AIRCRAFT MADE TWO ADDITIONAL PASSES
THROUGH THE CENTER OF THE TROPICAL CYCLONE AFTER THE RELEASE OF THE
2100 UTC NHC ADVISORY.  DURING THOSE PASSES...PEAK FLIGHT-LEVEL
WINDS OF 43-45 KT WERE RECORDED ALONG WITH A FEW BELIEVABLE SFMR
SURFACE WINDS JUST ABOVE TROPICAL STORM FORCE.  BASED ON THESE
OBSERVATIONS AND THE DEVELOPMENT OF NEW CONVECTION JUST NORTHEAST
OF THE CENTER AROUND 0000 UTC...THE DEPRESSION WAS UPGRADED TO A
TROPICAL STORM AT THAT TIME.  MICROWAVE AND SATELLITE IMAGERY SHOW
THAT MOST OF THE ASSOCIATED DEEP CONVECTION IS LOCATED OVER THE
EASTERN SEMICIRCLE OF THE CIRCULATION DUE TO MODERATE WESTERLY
SHEAR.  THE SHEAR IS FORECAST TO DECREASE SLIGHTLY DURING THE NEXT
12-24 HOURS...WHICH SHOULD ALLOW AN OPPORTUNITY FOR SOME
STRENGTHENING.  THE NHC INTENSITY FORECAST IS IN GOOD AGREEMENT
WITH THE SHIPS/LGEM GUIDANCE AND SHOWS PEAK INTENSITY OCCURRING
BETWEEN 24-36 HOURS.  WEAKENING IS INDICATED BEYOND 36 HOURS WHEN
THE GLOBAL MODELS PREDICT AN INCREASE IN UPPER-LEVEL NORTHEASTERLY
WINDS OVER THE CYCLONE.

BRET HAS BEEN DRIFTING EASTWARD DURING THE PAST FEW HOURS...BUT A
LONGER-TERM MOTION YIELDS 145/2.  THE TROPICAL STORM IS NOT
FORECAST TO MOVE VERY MUCH DURING THE NEXT 12-18 HOURS AS IT
REMAINS IN AN AREA OF WEAK STEERING CURRENTS.  IN 24-36 HOURS...THE
RIDGE TO THE SOUTHEAST OF BRET IS FORECAST TO STRENGTHEN WHICH
SHOULD PRODUCE A NORTHEASTWARD MOTION.  AS BRET GAINS LATITUDE IN
2-3 DAYS...IT SHOULD ACCELERATE EAST-NORTHEASTWARD WITHIN AN AREA
OF DEEP-LAYER WESTERLY FLOW.  THE LATEST HWRF AND GFDL MODEL
FORECASTS SHOW A MORE NORTH-NORTHEASTWARD MOTION WITH A TRACK MUCH
CLOSER TO THE UNITED STATES THAN THE USUALLY RELIABLE ECMWF AND GFS
MODELS.  THIS SCENARIO APPEARS UNLIKELY DUE TO THE STRENGTH OF THE
MID- TO UPPER-LEVEL RIDGE FORECAST OVER THE CENTRAL UNITED STATES. 
FOR NOW...THE OFFICIAL FORECAST PLACES MORE WEIGHT ON THE GLOBAL
MODELS AND IS VERY SIMILAR TO THE PREVIOUS NHC TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0300Z 27.5N  78.0W   35 KT  40 MPH
 12H  18/1200Z 27.7N  77.9W   40 KT  45 MPH
 24H  19/0000Z 28.5N  77.4W   50 KT  60 MPH
 36H  19/1200Z 29.7N  76.7W   50 KT  60 MPH
 48H  20/0000Z 30.7N  75.5W   45 KT  50 MPH
 72H  21/0000Z 32.5N  71.5W   40 KT  45 MPH
 96H  22/0000Z 34.5N  65.5W   35 KT  40 MPH
120H  23/0000Z 36.5N  58.5W   30 KT  35 MPH
 
$$
FORECASTER BROWN/BERG
 

WTNT42 KNHC 180853
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 AM EDT MON JUL 18 2011
 
THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING BRET
OVERNIGHT FOUND THAT THE CYCLONE HAS CONTINUED TO SLOWLY STRENGTHEN
...WITH THE CENTRAL PRESSURE FALLING TO 1001 MB.  THE INITIAL
INTENSITY IS RAISED TO 45 KT BASED ON A PEAK 850-MB FLIGHT-LEVEL
WIND OF 54 KT AND SOME BELIEVABLE 45 TO 50 KT SFMR WINDS OUTSIDE 
AREAS OF HEAVY RAIN AND SHALLOW WATERS NEAR THE ABACOS ISLANDS. 
SATELLITE AND RADAR IMAGERY SHOW THAT DEEP CONVECTION HAS INCREASED
NEAR THE CENTER AND IN A PROMINENT BAND IN THE EASTERN SEMICIRCLE
OVER THE PAST FEW HOURS...HOWEVER DRY AIR IS STILL IMPINGING ON THE
WESTERN HALF OF THE CIRCULATION.  ALSO...AN UPPER-LEVEL SHEAR AXIS
SITUATED JUST NORTHWEST OF BRET APPEARS TO BE HINDERING OUTFLOW IN
THE WESTERN SEMICIRCLE AND THE AIRCRAFT NOTED A 3 TO 5 NM
SOUTHEASTWARD TILT BETWEEN THE SURFACE AND 850-MB CENTERS.  THE
INTENSITY GUIDANCE IS CONSISTENT WITH THIS MARGINAL ENVIRONMENT AND
SUGGESTS THAT BRET HAS A PERIOD OF 24 TO 36 HOURS TO STEADILY
STRENGTHEN BEFORE THE SHEAR INCREASES MARKEDLY AND THE CYCLONE
BEGINS TO MOVE OVER COOLER WATERS.  THE OFFICIAL FORECAST HAS BEEN
NUDGED UPWARD IN AGREEMENT WITH THE SHIPS MODEL THROUGH 48 HOURS
AND A BLEND OF THE SHIPS AND LGEM BEYOND THAT TIME.
 
BRET JOGGED SOUTH-SOUTHEASTWARD OVERNIGHT...ALTHOUGH THE LATEST
AIRCRAFT FIXES AND DOPPLER RADAR IMAGERY FROM MIAMI SUGGEST THAT THE
CYCLONE HAS TURNED TOWARD THE EAST IN THE PAST COUPLE OF HOURS...
POSSIBLY COMPLETING A CYCLONIC LOOP.  THE LATEST AIRCRAFT FIXES
YIELD AN INITIAL MOTION ESTIMATE OF 090/03 KT.  ALL OF THE GUIDANCE
INSISTS THAT BRET WILL BEGIN TO MOVE SLOWLY NORTH-NORTHEASTWARD BY
TONIGHT AS THE CYCLONE COMES UNDER THE INFLUENCE OF A BUILDING
MID-LEVEL RIDGE TO ITS SOUTHEAST.  BY 48 HOURS AND BEYOND THE
GLOBAL MODELS SUGGEST THAT A BROAD MID-LEVEL TROUGH OFFSHORE OF THE
NORTHEASTERN U.S. WILL DEEPEN ENOUGH TO CAPTURE BRET AND ACCELERATE
THE CYCLONE INTO THE WESTERLIES BY THE END OF THE PERIOD.  GIVEN
THE EASTWARD MOVEMENT OF THE CYCLONE OVERNIGHT AND A GENERAL
WESTWARD TREND IN THE GUIDANCE ENVELOPE...THE NEW OFFICIAL FORECAST
IS SIMILAR TO THE PREVIOUS ONE THROUGH 48 HOURS AND LIES CLOSE TO A
BLEND OF THE ECMWF...UKMET...GFS...GFDL...AND HWRF MODELS.  AFTER
THAT TIME...THE NHC FORECAST IS ADJUSTED TOWARD THIS MODEL BLEND
AND IS LEFT OF AND A LITTLE SLOWER THAN THE PREVIOUS PACKAGE. 
FURTHER ADJUSTMENTS IN THIS DIRECTION MAY BE NECESSARY NEAR THE END
OF THE PERIOD IF THIS TREND IN THE GUIDANCE CONTINUES.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/0900Z 27.2N  77.7W   45 KT  50 MPH
 12H  18/1800Z 27.6N  77.7W   50 KT  60 MPH
 24H  19/0600Z 28.6N  77.2W   55 KT  65 MPH
 36H  19/1800Z 29.7N  76.5W   55 KT  65 MPH
 48H  20/0600Z 30.7N  75.4W   50 KT  60 MPH
 72H  21/0600Z 32.5N  71.5W   45 KT  50 MPH
 96H  22/0600Z 35.0N  67.0W   35 KT  40 MPH
120H  23/0600Z 38.0N  59.0W   30 KT  35 MPH
 
$$
FORECASTER BRENNAN
 

WTNT42 KNHC 181436
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 AM EDT MON JUL 18 2011
 
THE CLOUD PATTERN OF THE STORM HAS NOT CHANGED APPRECIABLY IN
ORGANIZATION THIS MORNING.  THE MAIN BANDING FEATURES ARE WELL
REMOVED FROM THE CENTER OVER THE NORTHEAST QUADRANT...AND A
SOMEWHAT RAGGED-LOOKING CDO TYPE FEATURE IS EVIDENT.  UPPER-LEVEL
OUTFLOW CONTINUES TO BE SUPPRESSED OVER THE NORTHWESTERN PART OF
THE CIRCULATION.  DVORAK INTENSITY ESTIMATES ARE 35 KT AND 45 KT
FROM TAFB AND SAB RESPECTIVELY...AND THE CURRENT INTENSITY ESTIMATE
IS HELD AT 45 KT.  ANOTHER AIR FORCE HURRICANE HUNTER MISSION IS
SCHEDULED TO INVESTIGATE BRET THIS AFTERNOON.  THE ATMOSPHERIC
ENVIRONMENT SHOULD BE MARGINALLY CONDUCIVE FOR STRENGTHENING TODAY
AND TONIGHT...WITH DRY AIR AND MODERATE VERTICAL SHEAR AS
MITIGATING FACTORS.  SOME INTENSIFICATION IS FORECAST WITHIN THE
NEXT DAY OR SO...BUT AFTERWARDS INCREASING SHEAR IS LIKELY TO CAUSE
A WEAKENING TREND.  THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO
THE CONSENSUS OF THE INTENSITY GUIDANCE...AND TO THE PREVIOUS NHC
FORECAST.

BASED ON THE LATEST FIXES...THE CENTER APPEARS TO BE MOVING SLOWLY
NORTH-NORTHEASTWARD OR 030/4.  THE TRACK FORECAST REASONING IS
ESSENTIALLY UNCHANGED FROM THE PREVIOUS ADVISORY PACKAGE.  A
BUILDING MID-LEVEL RIDGE TO THE SOUTHEAST OF BRET ALONG WITH A
BROAD TROUGH OFF THE NORTHEAST U.S. COAST SHOULD CAUSE A
NORTH-NORTHEASTWARD TO NORTHEASTWARD MOTION WITH A GRADUAL INCREASE
IN FORWARD SPEED OVER THE NEXT SEVERAL DAYS.  LATER IN THE FORECAST
PERIOD...A TURN TO THE EAST-NORTHEAST WITH SOME ADDITIONAL
ACCELERATION IS FORECAST AS THE CYCLONE BECOMES MORE EMBEDDED IN
THE HIGHER LATITUDE WESTERLIES.  THE OFFICIAL TRACK FORECAST IS AN
UPDATE OF THE PREVIOUS ONE.  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/1500Z 27.7N  77.3W   45 KT  50 MPH
 12H  19/0000Z 28.2N  77.0W   50 KT  60 MPH
 24H  19/1200Z 29.2N  76.4W   55 KT  65 MPH
 36H  20/0000Z 30.2N  75.7W   55 KT  65 MPH
 48H  20/1200Z 31.4N  74.0W   50 KT  60 MPH
 72H  21/1200Z 33.5N  70.0W   45 KT  50 MPH
 96H  22/1200Z 36.0N  64.5W   35 KT  40 MPH
120H  23/1200Z 38.5N  58.5W   30 KT  35 MPH
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 182056
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 PM EDT MON JUL 18 2011
 
VISIBLE SATELLITE IMAGERY THIS AFTERNOON SHOWED A RAGGED EYE-LIKE
FEATURE...SUGGESTING THAT SOME INTENSIFICATION HAD TAKEN PLACE. 
THIS WAS CONFIRMED BY OBSERVATIONS FROM THE AIR FORCE HURRICANE
HUNTER AIRCRAFT.  USING A BLEND OF PEAK FLIGHT-LEVEL...SFMR...AND
DROPSONDE WIND SPEED MEASUREMENTS THE CURRENT INTENSITY IS SET AT
55 KT.  THE SHIPS MODEL OUTPUT SHOWS A SUBSTANTIAL INCREASE IN
VERTICAL SHEAR WITHIN 12 TO 24 HOURS...SO BRET HAS A NARROW WINDOW
OF OPPORTUNITY TO STRENGTHEN SOME MORE BEFORE REACHING A LESS
CONDUCIVE ENVIRONMENT...AND IT COULD BE NEAR HURRICANE STRENGTH BY
EARLY TOMORROW OR SOONER.  THE OFFICIAL FORECAST FOLLOWS THE
INTENSITY MODEL CONSENSUS...IVCN.

AIRCRAFT AND SATELLITE FIXES GIVE A MOTION ESTIMATE OF AROUND 030/6.
THE TRACK FORECAST PHILOSOPHY HAS NOT CHANGED MUCH.  BRET SHOULD BE
STEERED NORTH-NORTHEASTWARD TO NORTHEASTWARD AROUND THE
NORTHWESTERN PERIPHERY OF A MID-LEVEL SUBTROPICAL HIGH OVER THE
NEXT COUPLE OF DAYS.  LATER IN THE FORECAST PERIOD...THE CYCLONE
SHOULD ACCELERATE SOMEWHAT TOWARD THE EAST-NORTHEAST AS IT BECOMES
MORE EMBEDDED WITHIN HIGHER-LATITUDE WESTERLY FLOW.  THE NHC
FORECAST FOR THIS ADVISORY IS SOMEWHAT FASTER THAN...AND SLIGHTLY
TO THE LEFT OF...THE PREVIOUS ONE.  THIS IS RATHER CLOSE TO THE
LATEST ECMWF TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  18/2100Z 28.3N  77.0W   55 KT  65 MPH
 12H  19/0600Z 29.2N  76.5W   60 KT  70 MPH
 24H  19/1800Z 30.4N  75.6W   60 KT  70 MPH
 36H  20/0600Z 31.5N  74.4W   55 KT  65 MPH
 48H  20/1800Z 33.0N  72.5W   50 KT  60 MPH
 72H  21/1800Z 35.5N  67.5W   40 KT  45 MPH
 96H  22/1800Z 39.0N  60.0W   35 KT  40 MPH
120H  23/1800Z 43.0N  52.0W   30 KT  35 MPH...POST-TROP/EXTRATROP
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 190248
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 PM EDT MON JUL 18 2011
 
THE AIR FORCE RESERVE HURRICANE HUNTER MISSION FROM EARLIER THIS
AFTERNOON MADE ONE MORE PASS THROUGH THE CENTER OF BRET AFTER THE
RELEASE OF THE 2100 UTC ADVISORY AND ESSENTIALLY FOUND LITTLE
CHANGE TO THE WINDS.  HOWEVER...THE CENTRAL PRESSURE INCREASED BY 1
MB ON EACH SUCCESSIVE PASS OF THE AIRCRAFT...AND THE INTENSITY OF
THE DEEP CONVECTION HAS BEEN ON A DOWNWARD TREND OVER THE PAST FEW
HOURS.  THE INTENSITY ON THIS ADVISORY IS THEREFORE LOWERED TO 50
KT.  MOST OF THE INTENSITY GUIDANCE STILL GIVES BRET THE OPPORTUNITY
FOR SOME RE-STRENGTHENING DURING THE NEXT 12 HOURS OR SO...AND THE
OFFICIAL FORECAST INDICATES THIS POSSIBILITY SHOULD THE DEEP
CONVECTION RE-DEVELOP OVERNIGHT.  MORE CERTAIN WEAKENING SHOULD
COMMENCE BEYOND 24 HOURS AS THE VERTICAL SHEAR BECOMES INCREASINGLY
HOSTILE...AND BRET IS EXPECTED TO DISSIPATE WITHIN SOUTHWESTERLY
MID-LATITUDE FLOW SOUTH OF THE CANADIAN MARITIMES BY DAY 5.
 
BRET STILL APPEARS TO BE MOVING AT AN AVERAGE MOTION OF 030/6.  THE
CYCLONE IS EXPECTED TO ACCELERATE NORTHEASTWARD AROUND THE
NORTHWESTERN PERIPHERY OF A MID-LEVEL HIGH...BUT THE TRACK GUIDANCE
IS A LITTLE SLOWER ON THIS MOTION FOR THIS FORECAST CYCLE.  THE
ECMWF IS THE FASTEST OF THE GUIDANCE...BUT IT IS NOW 12 HOURS OLD
AND...ALONG WITH OFCI...FELL VERY NEAR THE EDGE OF THE GPCE CIRCLE
FAR FROM THE OTHER RELIABLE MODELS AT 72 HOURS.  THE NEW OFFICIAL
TRACK FORECAST IS SHIFTED IN THE DIRECTION OF THE MODEL CONSENSUS
AND IS THEREFORE ON TRACK WITH BUT A LITTLE SLOWER THAN THE
PREVIOUS NHC FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0300Z 28.7N  76.6W   50 KT  60 MPH
 12H  19/1200Z 29.5N  76.1W   55 KT  65 MPH
 24H  20/0000Z 30.6N  75.1W   55 KT  65 MPH
 36H  20/1200Z 31.7N  73.8W   50 KT  60 MPH
 48H  21/0000Z 33.1N  71.9W   50 KT  60 MPH
 72H  22/0000Z 36.0N  67.0W   40 KT  45 MPH
 96H  23/0000Z 39.0N  59.0W   30 KT  35 MPH
120H  24/0000Z...DISSIPATED
 
$$
FORECASTER BERG
 

WTNT42 KNHC 190839
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 AM EDT TUE JUL 19 2011
 
DEEP CONVECTION HAS ALL BUT DISAPPEARED NEAR THE CENTER OF BRET IN
THE PAST FEW HOURS...LIKELY DUE TO THE ENTRAINMENT OF DRY AIR INTO
THE CYCLONE CORE AS SEEN IN SATELLITE IMAGERY AND DEWPOINT DATA
FROM THE AIR FORCE RESERVE UNIT HURRICANE HUNTER AIRCRAFT.  THE
INITIAL INTENSITY IS LOWERED TO 45 KT BASED ON A 850-MB FLIGHT-
LEVEL WIND MAXIMUM OF 55 KT AND A PEAK SFMR WIND OF 43 KT.  THE
DRIER ENVIRONMENT AND A FORECAST OF INCREASING VERTICAL WIND SHEAR
ARE NOT FAVORABLE FOR RESTRENGTHENING...AND THE INTENSITY GUIDANCE
SHOWS BRET SLOWLY WEAKENING FROM THIS POINT FORWARD.  THE NEW NHC
FORECAST FOLLOWS THIS REASONING AND SHOWS LITTLE CHANGE THROUGH 12
HOURS FOLLOWED BY GRADUAL WEAKENING UNTIL DISSIPATION IN ABOUT 96
HOURS...IN BEST AGREEMENT WITH THE LGEM.  HOWEVER...IF DEEP
CONVECTION DOES NOT RETURN...BRET COULD WEAKEN AND DISSIPATE MORE
QUICKLY THAN INDICATED HERE.
 
AIRCRAFT FIXES SUGGEST THAT THE LONG-TERM INITIAL MOTION IS TOWARD
THE NORTH-NORTHEAST OR 025 DEGREES AT AROUND 6 KT...A LITTLE TO THE
LEFT OF THE PREVIOUS FORECAST TRACK.  OVERALL...THE TRACK FORECAST
REASONING REMAINS UNCHANGED AS BRET WILL GRADUALLY ACCELERATE TOWARD
THE NORTHEAST OVER THE NEXT COUPLE OF DAYS AS A MID-LEVEL RIDGE
BUILDS TO THE SOUTHEAST OF THE CYCLONE.  THROUGH 48 HOURS...THE
GUIDANCE IS TIGHTLY CLUSTERED AND THE NEW OFFICIAL FORECAST HAS
BEEN ADJUSTED A LITTLE TO THE LEFT OF THE PREVIOUS ONE TO ACCOUNT
FOR THE INITIAL POSITION AND MOTION.  AT 72 HOURS A MORE SUBSTANTIAL
ADJUSTMENT WAS MADE...TO THE LEFT OF AND SLOWER THAN THE PREVIOUS
NHC FORECAST...TRENDING TOWARD THE NEW MULTI-MODEL CONSENSUS.

 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/0900Z 29.3N  76.4W   45 KT  50 MPH
 12H  19/1800Z 30.0N  75.8W   45 KT  50 MPH
 24H  20/0600Z 30.9N  74.8W   40 KT  45 MPH
 36H  20/1800Z 32.1N  73.4W   35 KT  40 MPH
 48H  21/0600Z 33.6N  71.9W   35 KT  40 MPH
 72H  22/0600Z 36.5N  68.0W   30 KT  35 MPH
 96H  23/0600Z...DISSIPATED
 
$$
FORECASTER BRENNAN
 

WTNT42 KNHC 191437
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 AM EDT TUE JUL 19 2011
 
DEEP CONVECTION HAS BEEN RATHER MEAGER IN ASSOCIATION WITH BRET THIS
MORNING.  A FEW THUNDERSTORMS REDEVELOPED OVER THE SOUTHWESTERN
PORTION OF THE CIRCULATION...BUT RECENTLY THIS CONVECTION HAS BEEN
ON THE WANE.  VISIBLE SATELLITE IMAGES SHOW THAT THE LOW-LEVEL
CENTER OF THE STORM IS EXPOSED NEAR THE NORTHERN EDGE OF THE SMALL
DENSE OVERCAST.  THE INTENSITY IS HELD AT 45 KT BASED ON A BLEND OF
DVORAK ESTIMATES FROM TAFB AND SAB...ALTHOUGH THIS IS PROBABLY A
GENEROUS ESTIMATE.  BRET IS BEING IMPACTED BY STRONG NORTHEASTERLY
SHEAR AND IS ENTRAINING RATHER DRY MID-TROPOSPHERIC AIR.  THE
ENVIRONMENT IS LIKELY TO REMAIN HOSTILE...WHICH SHOULD RESULT IN
WEAKENING OVER THE NEXT FEW DAYS AND DISSIPATION AFTER 72 HOURS...IF
NOT SOONER.  THE OFFICIAL WIND SPEED FORECAST IS SIMILAR TO THE
PREVIOUS ONE.

INITIAL MOTION IS AROUND 030/7.  VERY LITTLE CHANGE HAS BEEN MADE TO
THE TRACK FORECAST FROM THE PREVIOUS ADVISORY.  BRET SHOULD
CONTINUE TO MOVE AROUND THE NORTHWESTERN PERIPHERY OF A MID-LEVEL
SUBTROPICAL ANTICYCLONE FOR THE NEXT DAY OR SO...AND BEGIN TO
INTERACT WITH THE MID-LATITUDE WESTERLIES LATER ON.  THE FORECAST
SHOWS A GRADUAL TURN TO THE NORTHEAST WITH SOME INCREASE IN FORWARD
SPEED OVER THE NEXT 72 HOURS...ASSUMING BRET SURVIVES THAT LONG. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  19/1500Z 29.9N  75.9W   45 KT  50 MPH
 12H  20/0000Z 30.6N  75.1W   45 KT  50 MPH
 24H  20/1200Z 31.6N  73.9W   40 KT  45 MPH
 36H  21/0000Z 32.9N  72.3W   35 KT  40 MPH
 48H  21/1200Z 34.3N  70.6W   30 KT  35 MPH
 72H  22/1200Z 37.5N  66.5W   25 KT  30 MPH
 96H  23/1200Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 192033
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 PM EDT TUE JUL 19 2011
 
BRET HAS A DISHEVELED APPEARANCE ON SATELLITE PICTURES...WITH AN
EXPOSED LOW-CLOUD CENTER TO THE NORTH-NORTHEAST OF A SMALL PATCH OF
THUNDERSTORMS.  IN SPITE OF THIS...DATA FROM THE AIR FORCE
HURRICANE HUNTERS INDICATE THAT THE EARLIER ESTIMATE OF INTENSITY
WAS NOT A GENEROUS ONE AND THE STORM IS MAINTAINING STRENGTH...FOR
NOW.  PEAK FLIGHT-LEVEL WINDS WERE 52 KT AND EVEN HIGHER SURFACE
WINDS WERE SHOWN BY THE SFMR INSTRUMENT ON BOARD THE AIRCRAFT.
HOWEVER THE SFMR WINDS APPEAR TO BE SOMEWHAT INFLATED BY AN
ACCOMPANYING SPIKE OF HEAVY RAIN.  THE INTENSITY ESTIMATE IS
MAINTAINED AT 45 KT.  STRONG NORTHERLY AND NORTHEASTERLY SHEAR
ALONG WITH DRY MID-TROPOSPHERIC AIR ARE EXPECTED TO TAKE A TOLL ON
BRET AND THE SYSTEM IS FORECAST TO WEAKEN TO DISSIPATION AFTER 3
DAYS.  THIS IS IN AGREEMENT WITH THE STATISTICAL-DYNAMICAL
INTENSITY GUIDANCE.
 
INITIAL MOTION IS ESTIMATED TO BE 035/7.  BRET IS MOVING AROUND THE
NORTHWESTERN PERIPHERY OF A SUBTROPICAL ANTICYCLONE AND SHOULD BE
APPROACHING THE MID-LATITUDE WESTERLIES LATER IN THE FORECAST
PERIOD.  DYNAMICAL TRACK MODELS ARE IN FAIRLY GOOD AGREEMENT ON A
CONTINUED GENERALLY NORTHEASTWARD MOTION WITH SOME ACCELERATION
OVER THE NEXT FEW DAYS.  THE CURRENT NHC FORECAST IS AN UPDATE OF
THE PREVIOUS ONE.

FORECAST POSITIONS AND MAX WINDS
 
INIT  19/2100Z 30.4N  75.5W   45 KT  50 MPH
 12H  20/0600Z 31.1N  74.5W   45 KT  50 MPH
 24H  20/1800Z 32.4N  73.0W   40 KT  45 MPH
 36H  21/0600Z 33.7N  71.5W   35 KT  40 MPH
 48H  21/1800Z 35.1N  69.8W   30 KT  35 MPH
 72H  22/1800Z 38.5N  65.0W   25 KT  30 MPH
 96H  23/1800Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 200239
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  10
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 PM EDT TUE JUL 19 2011
 
BRET HAS CHANGED LITTLE IN STRUCTURE SINCE THE LAST HURRICANE HUNTER
MISSION.  THE CYCLONE STILL CONSISTS OF AN EXPOSED LOW-LEVEL CENTER
AND PERSISTENT THUNDERSTORM ACTIVITY LOCATED OVER THE SOUTHWESTERN
QUADRANT.  THE INITIAL INTENSITY IS BEING HELD AT 45 KT SINCE THERE
HAS BEEN NO APPRECIABLE CHANGE IN THE SATELLITE PRESENTATION.  IN
FACT...IT COULD BE ARGUED THAT THE THUNDERSTORMS INCREASED IN
INTENSITY AROUND 0000 UTC...AND THE INTENSITY OF 45 KT IS
CORROBORATED BY A TAFB DATA-T ESTIMATE OF T3.0 USING THE SHEAR
PATTERN.  ANOTHER HURRICANE HUNTER FLIGHT WILL BE INVESTIGATING THE
STORM IN A FEW HOURS TO ASSESS IF THERE HAVE BEEN ANY CHANGES. 
STRONG NORTHERLY TO NORTHEASTERLY SHEAR AND DRY MID-LEVEL AIR ARE
EXPECTED TO CONTINUE IMPACTING BRET...AND THE OFFICIAL INTENSITY
FORECAST IS IN CLOSE AGREEMENT WITH THE INTENSITY CONSENSUS.  MOST
OF THE GLOBAL MODELS OPEN THE LOW-LEVEL CIRCULATION INTO A TROUGH
IN A COUPLE OF DAYS...THEREFORE DISSIPATION IS EXPECTED BY 72
HOURS.

BRET APPEARS TO HAVE TEMPORARILY SLOWED DOWN BUT SHOULD RESUME A
MOTION OF 040 DEGREES AT 7 KT SHORTLY.  THE CYCLONE IS EXPECTED TO
GRADUALLY ACCELERATE TO THE NORTHEAST OVER THE NEXT COUPLE OF DAYS
AS IT BECOMES INCREASINGLY EMBEDDED IN SOUTHWESTERLY MID-LATITUDE
FLOW.  THE DYNAMICAL TRACK MODELS ARE TIGHTLY CLUSTERED THROUGH 48
HOURS...AND NO MAJOR CHANGES WERE REQUIRED TO THE OFFICIAL TRACK
FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0300Z 30.6N  75.0W   45 KT  50 MPH
 12H  20/1200Z 31.5N  74.0W   40 KT  45 MPH
 24H  21/0000Z 32.8N  72.5W   40 KT  45 MPH
 36H  21/1200Z 34.2N  70.9W   35 KT  40 MPH
 48H  22/0000Z 35.8N  68.6W   30 KT  35 MPH
 72H  23/0000Z...DISSIPATED
 
$$
FORECASTER BERG
 

WTNT42 KNHC 200849
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  11
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 AM EDT WED JUL 20 2011
 
ALTHOUGH BRET IS ONLY PRODUCING A SMALL AMOUNT OF DEEP CONVECTION
THIS MORNING...DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTERS
INDICATE THAT THE STORM HAS NOT WEAKENED YET.  FLIGHT-LEVEL WINDS
...SFMR WINDS...AND DROPSONDE DATA ALL SUGGEST AN INITIAL INTENSITY
OF 45 KT.  GRADUAL WEAKENING IS STILL FORECAST AS THE ATMOSPHERIC
ENVIRONMENT IS EXPECTED TO REMAIN HOSTILE WITH NORTH-NORTHEASTERLY
SHEAR NEAR 30 KT AND RATHER DRY MID-LEVEL AIR BEING ENTRAINED INTO
THE CYCLONE.  THE NHC INTENSITY FORECAST IS UNCHANGED FROM EARLIER
AND CALLS FOR BRET TO DISSIPATE BY DAY 3...IN AGREEMENT WITH MOST
OF THE GUIDANCE.
 
AIRCRAFT AND SATELLITE FIXES INDICATE THAT BRET HAS TURNED A BIT TO
THE RIGHT DURING THE PAST 6 TO 12 HOURS...AND THE INITIAL MOTION
ESTIMATE IS 050/06.  A NORTHEASTWARD MOTION WITH A GRADUAL INCREASE
IN FORWARD SPEED IS FORECAST UNTIL DISSIPATION.  THE TRACK MODEL
GUIDANCE IS IN GOOD AGREEMENT...AND THE NEW OFFICIAL FORECAST IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS ONE.
 
THE 34-KT WIND AND 12-FT SEAS RADII HAVE BEEN ADJUSTED BASED ON
AIRCRAFT AND ALTIMETER DATA...RESPECTIVELY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/0900Z 31.1N  74.4W   45 KT  50 MPH
 12H  20/1800Z 31.9N  73.4W   40 KT  45 MPH
 24H  21/0600Z 33.2N  71.9W   40 KT  45 MPH
 36H  21/1800Z 34.6N  70.2W   35 KT  40 MPH
 48H  22/0600Z 36.2N  68.0W   30 KT  35 MPH
 72H  23/0600Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI
 

WTNT42 KNHC 201440
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  12
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 AM EDT WED JUL 20 2011
 
WHILE THE OVERALL CLOUD PATTERN REMAINS THAT OF A SHEARED
CYCLONE...CONVECTION HAS FLARED UP NEAR AND TO THE SOUTH OF THE
CENTER OF BRET THIS MORNING.  ANALYSES FROM CIMSS AT THE UNIVERSITY
OF WISCONSIN SUGGEST ABOUT 20 KT OF NORTHERLY VERTICAL WIND SHEAR
OVER THE SYSTEM...WHICH IS A LITTLE LESS THEN EARLIER.  THE INITIAL
INTENSITY REMAINS 45 KT BASED ON THE CONVECTIVE TRENDS AND DATA
FROM THE PREVIOUS AIRCRAFT MISSION.  ANOTHER AIRCRAFT WILL
INVESTIGATE BRET THIS AFTERNOON.

THE INITIAL MOTION IS 045/8.  BRET IS EMBEDDED IN LOW/MID-LEVEL
SOUTHWESTERLY FLOW ON THE NORTH SIDE OF THE SUBTROPICAL RIDGE...AND
THIS PATTERN SHOULD PRODUCE A NORTHEASTWARD MOTION UNTIL THE SYSTEM
DISSIPATES.  THE NEW FORECAST TRACK IS AGAIN AN UPDATE OF THE
PREVIOUS FORECAST.

WHILE THE SHEAR HAS DECREASED SLIGHTLY...THE LARGE-SCALE MODELS
FORECAST IT TO INCREASE AGAIN AFTER ABOUT 12 HR.  IN ADDITION...
WATER VAPOR IMAGERY SHOWS A LARGE AREA OF UPPER-LEVEL DRY AND
SUBSIDENCE OVER THE MID-ATLANTIC STATES MOVING SOUTHEASTWARD TOWARD
BRET.  THIS COMBINATION SHOULD WEAKEN THE STORM AND LEAD TO ITS
DISSIPATION IN 48-72 HR.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/1500Z 31.8N  73.7W   45 KT  50 MPH
 12H  21/0000Z 32.5N  72.7W   45 KT  50 MPH
 24H  21/1200Z 33.8N  71.1W   40 KT  45 MPH
 36H  22/0000Z 35.4N  69.2W   35 KT  40 MPH
 48H  22/1200Z 37.0N  66.5W   30 KT  35 MPH
 72H  23/1200Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 202035
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  13
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 PM EDT WED JUL 20 2011

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT FOUND THAT BRET HAS
WEAKENED A LITTLE.  THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS WERE 45
KT IN THE SOUTHEASTERN QUADRANT...AND THE CENTRAL PRESSURE WAS 1005
MB ON BOTH PASSES THROUGH THE CENTER.  BASED ON THIS AND DATA FROM
A 1521 UTC ASCAT OVERPASS...THE INITIAL INTENSITY IS REDUCED TO 40
KT.  WHILE THE SYSTEM IS STILL GENERATING CONVECTION SOUTH OF THE
CENTER...THE INTENSITY FORECAST CALLS FOR ADDITIONAL WEAKENING AS
DRY MID/UPPER-LEVEL AIR ADVECTS INTO THE CYCLONE FROM THE
NORTHWEST.  BRET IS NOW FORECAST TO WEAKEN TO A REMNANT LOW IN 48
HR AND DISSIPATE COMPLETELY BY 72 HR.
 
AIRCRAFT AND SATELLITE DATA INDICATE THAT THE CENTER JOGGED TO THE
EAST THIS AFTERNOON.  HOWEVER...THE OVERALL MOTION REMAINS
GENERALLY NORTHEASTWARD...050/7.  BRET REMAINS EMBEDDED IN
LOW/MID-LEVEL SOUTHWESTERLY FLOW ON THE NORTH SIDE OF THE
SUBTROPICAL RIDGE...AND THIS PATTERN SHOULD PRODUCE A NORTHEASTWARD
MOTION UNTIL THE SYSTEM DISSIPATES.  THE NEW FORECAST TRACK IS
SIMILAR TO THE PREVIOUS TRACK...BUT NUDGED A LITTLE TO THE EAST
BASED ON THE INITIAL POSITION.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  20/2100Z 31.9N  73.0W   40 KT  45 MPH
 12H  21/0600Z 32.7N  72.0W   40 KT  45 MPH
 24H  21/1800Z 34.3N  70.3W   35 KT  40 MPH
 36H  22/0600Z 35.9N  68.0W   30 KT  35 MPH
 48H  22/1800Z 37.8N  64.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  23/1800Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 210257
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  14
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 PM AST WED JUL 20 2011
 
FOR THE PAST SEVERAL HOURS...BRET HAS LOST MUCH OF THE DEEP
CONVECTION THAT WAS LOCATED SOUTH OF ITS EXPOSED LOW-LEVEL
CENTER...AND NOW ONLY A FEW THUNDERSTORMS REMAIN.  OBJECTIVE 3-HOUR
ADT NUMBERS ARE CURRENTLY T2.6...AND THE RAW NUMBERS ARE MUCH
LOWER.  THE INITIAL INTENSITY IS THEREFORE LOWERED TO 35 KT.
 
NORTHERLY SHEAR OVER BRET IS BRUTAL.  THE SHIPS/LGEM DIAGNOSTICS
SHOW ABOUT 30-35 KT OF SHEAR AFFECTING THE SYSTEM...AND THESE
VALUES COULD INCREASE FURTHER OVER THE NEXT 12-24 HOURS.  WITH
WATER VAPOR IMAGERY SHOWING AN AREA OF STRONG SUBSIDENCE MOVING
SOUTHWARD TOWARDS THE CYCLONE...BRET WILL LIKELY STRUGGLE TO
MAINTAIN SIGNIFICANT DEEP CONVECTION OVER THE NEXT DAY.  THE
OFFICIAL FORECAST ESSENTIALLY MIRRORS THE STATISTICAL-DYNAMICAL
MODELS...AND BRET COULD DEGENERATE INTO A REMNANT LOW BY 36
HOURS...IF NOT SOONER.  DISSIPATION IS NOW EXPECTED BY 48 HOURS.
 
AFTER JOGGING TO THE EAST EARLIER THIS AFTERNOON...BRET IS NOW
WOBBLING A BIT TO THE NORTH.  THE AVERAGE MOTION REMAINS
NORTHEASTWARD WITH A BIT OF AN ACCELERATION AT 045/8.  THE TRACK
GUIDANCE IS IN GENERALLY GOOD AGREEMENT IN SHOWING ACCELERATION
WITHIN FASTER MID-LATITUDE SOUTHWESTERLIES...AND THE NEW OFFICIAL
FORECAST WAS ADJUSTED JUST A LITTLE TO THE EAST OF THE PREVIOUS ONE
TO BE CLOSE TO THE FASTER-MOVING GFS AND ECMWF.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0300Z 32.8N  72.6W   35 KT  40 MPH
 12H  21/1200Z 33.9N  70.9W   35 KT  40 MPH
 24H  22/0000Z 35.5N  68.5W   30 KT  35 MPH
 36H  22/1200Z 37.2N  65.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  23/0000Z...DISSIPATED
 
$$
FORECASTER BERG
 

WTNT42 KNHC 210859
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  15
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 AM AST THU JUL 21 2011
 
DURING THE PAST 6 HOURS...CONVECTION WITH CLOUD TOPS TO -70C HAS
REDEVELOPED IN THE SOUTHERN QUADRANT AS NORTHERLY VERTICAL SHEAR
HAS ABATED SLIGHTLY. SATELLITE DATA-T NUMBERS FROM BOTH TAFB AND
SAB ARE T2.5/35 KT. SHIP WPGK PASSED THROUGH THE SOUTHERN QUADRANT
AROUND 0300Z...BEFORE CONVECTION HAD REDEVELOPED...AND REPORTED A
WIND SPEED OF 32 KT. BASED ON THESE DATA...THE INITIAL INTENSITY OF
BRET IS BEING MAINTAINED AT 35 KT.
 
THE MOTION ESTIMATE IS 050/07. THERE IS NO SIGNIFICANT CHANGE TO THE
PREVIOUS FORECAST TRACK OR REASONING. BRET IS GRADUALLY BEING
CAUGHT UP BY THE MID-LATITUDE WESTERLIES...BUT ITS FORWARD PROGRESS
IS BEING IMPEDED BY NORTHERLY WIND SHEAR THAT IS FORECAST TO BECOME
NORTHEASTERLY DURING THE NEXT 24 HOURS. AS A RESULT...ONLY SLOW
FORWARD PROGRESS IS EXPECTED FOR THE NEXT DAY OR SO UNTIL THE
CYCLONE WEAKENS AND IS STEERED MORE QUICKLY TO THE NORTHEAST BY
LOW- TO MID-LEVEL SOUTHWESTERLY FLOW ON THE NORTH SIDE OF A STRONG
SUBTROPICAL RIDGE LOCATED ALONG 30N LATITUDE. THE OFFICIAL FORECAST
TRACK IS SIMILAR TO BUT FASTER THAN THE PREVIOUS ADVISORY AND IS
BASICALLY DOWN THE MIDDLE OF THE TIGHTLY PACKED NHC MODEL GUIDANCE.
 
ALTHOUGH THE NORTHERLY SHEAR ACROSS BRET IS FORECAST TO INCREASE
DURING THE NEXT 12-18 HOURS...THE 200 MB WIND FIELDS ACTUALLY SHOW
THE SHEAR DECREASING BY 24 HOURS. FOR THIS REASON...BRET IS BEING
HELD ONTO AS A TROPICAL DEPRESSION A LITTLE LONGER THAN SOME OF THE
MODEL GUIDANCE IS FORECASTING. HOWEVER...AFTER 36 HOURS THE SEA
SURFACE TEMPERATURES BENEATH THE CYCLONE ARE FORECAST TO DROP BELOW
26C...AND THAT SHOULD RESULT IN DEGENERATION INTO A REMNANT LOW
PRESSURE SYSTEM. BY 48 HOURS...BRET IS FORECAST TO DISSIPATE
COMPLETELY OVER MUCH COLDER 20-22C SST WATER.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/0900Z 33.1N  71.7W   35 KT  40 MPH
 12H  21/1800Z 34.4N  70.0W   30 KT  35 MPH
 24H  22/0600Z 36.2N  67.6W   30 KT  35 MPH
 36H  22/1800Z 37.8N  64.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  23/0600Z...DISSIPATED
 
$$
FORECASTER STEWART
 

WTNT42 KNHC 211439
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 AM AST THU JUL 21 2011

WHILE BRET CONTINUES TO GENERATE A STRONG CONVECTIVE CLUSTER SOUTH
OF THE EXPOSED LOW-LEVEL CENTER...THE SYSTEM IS GRADUALLY LOSING
ORGANIZATION AS IT REMAINS AFFECTED BY NORTHERLY VERTICAL WIND
SHEAR.  THERE IS NO RECENT DATA FROM NEAR THE CENTER.  HOWEVER...
TROPICAL-STORM WINDS COULD STILL BE OCCURRING IN AND NEAR THE
CONVECTION BASED ON A 1-MINUTE WIND OF 33 KT RECENTLY OBSERVED AT
BUOY 41048.  THUS...THE INITIAL INTENSITY REMAINS A POSSIBLY
GENEROUS 35 KT.
 
THE INITIAL MOTION IS 055/8.  THERE IS NO SIGNIFICANT CHANGE TO THE
PREVIOUS FORECAST TRACK OR REASONING.  BRET SHOULD MOVE
NORTHEASTWARD IN THE FLOW ON THE NORTH SIDE OF THE SUBTROPICAL
RIDGE UNTIL IT DISSIPATES...WITH A GRADUAL INCREASE IN FORWARD
SPEED DURING THAT TIME.  THE NEW FORECAST TRACK IS SIMILAR TO THE
PREVIOUS ADVISORY.

BRET IS MOVING THROUGH AN AREA OF MID/UPPER-LEVEL DRY AIR...AND IT
IS EXPECTED TO ENCOUNTER GRADUALLY DECREASING SEA SURFACE
TEMPERATURES ALONG THE FORECAST TRACK.  THIS COMBINATION IS LIKELY
TO CAUSE THE CYCLONE TO WEAKEN EVEN THOUGH THE SHEAR IS EXPECTED TO
DECREASE DURING THE NEXT FEW DAYS.  ALL OF THE INTENSITY GUIDANCE
FORECAST THE SYSTEM TO DISSIPATE DURING THE NEXT TWO TO THREE
DAYS...AND THE INTENSITY FORECAST FOLLOWS THIS SCENARIO.  THE NEW
INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/1500Z 33.8N  70.6W   35 KT  40 MPH
 12H  22/0000Z 35.0N  69.0W   30 KT  35 MPH
 24H  22/1200Z 36.8N  66.1W   30 KT  35 MPH
 36H  23/0000Z 38.6N  62.1W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  23/1200Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 212037
TCDAT2
 
TROPICAL STORM BRET DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 PM AST THU JUL 21 2011

THE CENTER OF BRET REMAINS EXPOSED TO THE NORTHEAST OF A PERSISTENT
CLUSTER OF CONVECTION.  AN ASCAT OVERPASS AT 1500 UTC SHOWED AN
AREA OF 30-35 KT WINDS SOUTHEAST OF THE CENTER.  BASED ON THIS AND
THE RELATIVELY UNCHANGED APPEARANCE OF THE CYCLONE OVER THE PAST
FEW HOURS...THE INITIAL INTENSITY REMAINS 35 KT.  ANALYSES FROM THE
SHIPS MODEL AND FROM CIMSS AT THE UNIVERSITY OF WISCONSIN INDICATE
THAT THE NORTHEASTERLY VERTICAL WIND SHEAR HAS INCREASED TO
35-40 KT...AND THIS IS ADVECTING MID/UPPER-LEVEL DRY AIR INTO THE
CYCLONE.  ALL OF THE GLOBAL MODELS SHOW BRET WEAKENING TO A TROUGH
IN 48 HR OR LESS...AND THEREFORE THE INTENSITY FORECAST FOLLOWS
SUIT.  THE NEW INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS
ADVISORY.
 
THE INITIAL MOTION IS A LITTLE MORE TO THE RIGHT AT 060/9.  OTHER
THAN THAT...THERE IS NO SIGNIFICANT CHANGE TO THE PREVIOUS TRACK
FORECAST REASONING.  BRET SHOULD MOVE GENERALLY NORTHEASTWARD TO
EAST-NORTHEASTWARD IN THE FLOW ON THE NORTH SIDE OF THE SUBTROPICAL
RIDGE UNTIL IT DISSIPATES...WITH A GRADUAL INCREASE IN FORWARD
SPEED DURING THAT TIME.  THE NEW FORECAST TRACK IS SIMILAR TO...BUT
A LITTLE TO THE RIGHT OF...THE PREVIOUS ADVISORY FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  21/2100Z 34.2N  69.7W   35 KT  40 MPH
 12H  22/0600Z 35.5N  67.3W   30 KT  35 MPH
 24H  22/1800Z 37.3N  63.8W   25 KT  30 MPH
 36H  23/0600Z 39.0N  59.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  23/1800Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 220256
TCDAT2
 
TROPICAL DEPRESSION BRET DISCUSSION NUMBER  18
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
1100 PM AST THU JUL 21 2011
 
THE SYSTEM LOST ESSENTIALLY ALL OF ITS DEEP CONVECTION SEVERAL HOURS
AGO...AND IT IS ESTIMATED THAT BRET HAS NOW WEAKENED TO A TROPICAL
DEPRESSION.  THE ENVIRONMENT IS EXPECTED TO REMAIN HOSTILE FOR THE
MAINTENANCE OF A TROPICAL CYCLONE WITH STRONG SHEAR AND COOLING
WATERS...AND THE CYCLONE IS FORECAST TO DEGENERATE INTO A REMNANT
LOW IN ABOUT 36 HOURS.  HOWEVER...GIVEN THE CURRENT STATUS OF
BRET...THE SYSTEM COULD LOSE ITS TROPICAL CYCLONE STATUS MUCH
SOONER THAN THAT.

BRET HAS ACCELERATED AND THE INITIAL MOTION IS NOW 050/12...PERHAPS
A LITTLE FASTER.  THE SYSTEM SHOULD CONTINUE TO MOVE IN THE FLOW TO
THE NORTH OF THE MID- TO LOW-LEVEL SUBTROPICAL RIDGE UNTIL
DISSIPATION.  THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE
AND CLOSE TO THE TRACK MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0300Z 35.6N  68.1W   30 KT  35 MPH
 12H  22/1200Z 36.9N  65.8W   30 KT  35 MPH
 24H  23/0000Z 38.4N  61.8W   25 KT  30 MPH
 36H  23/1200Z 40.0N  57.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  24/0000Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 220853
TCDAT2
 
TROPICAL DEPRESSION BRET DISCUSSION NUMBER  19
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL022011
500 AM AST FRI JUL 22 2011
 
BRET REMAINS A MAVERICK TROPICAL CYCLONE BY REFUSING TO DISSIPATE
DESPITE EXPERIENCING VERY HOSTILE VERTICAL WIND SHEAR CONDITIONS
OVER THE PAST 12 HOURS. PREVIOUSLY DEVOID OF ANY CONVECTION...SOME
MODEST CONVECTION WITH CLOUD TOPS TO -45C HAS RECENTLY DEVELOPED IN
THE SOUTHEAST QUADRANT. IN ADDITION...SHIP WDC6925 LOCATED ABOUT 
80 NMI SOUTH OF THE CENTER REPORTED A SOUTHWEST WIND OF 24 KT AT
06Z. THIS INFORMATION...COMBINED WITH A SATELLITE INTENSITY
ESTIMATE OF T2.0/30 KT FROM TAFB...IS JUSTIFICATION FOR MAINTAINING
BRET AS A 30-KT DEPRESSION FOR THIS ADVISORY.

BRET HAS CONTINUED TO ACCELERATE AND THE INITIAL MOTION IS NOW
055/18. THE CYCLONE IS FORECAST TO MOVE TOWARD THE NORTHEAST TODAY
AND TURN TOWARD THE EAST-NORTHEAST BY 24 HOURS AS THE CYCLONE MOVES
ALONG THE NORTHERN PERIPHERY OF A DEEP LAYER SUBTROPICAL RIDGE
SITUATED ALONG 30N LATITUDE. THIS WILL RESULT IN BRET MOVING OVER
MUCH COLDER WATERS...WHICH WILL HASTEN ITS DEMISE. THE OFFICIAL
FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY AND IS CLOSE TO
THE TRACK MODEL CONSENSUS.

DURING THE NEXT 12-18 HOURS...A NARROW UPPER-LEVEL RIDGE LOCATED
JUST TO THE NORTHWEST OF BRET IS FORECAST BY ALL OF THE GLOBAL
MODELS TO SLIDE SOUTHEASTWARD AND PASS OVER THE CYCLONE. THIS WILL
BRIEFLY REDUCE THE WIND SHEAR...WHICH MAY ALLOW FOR ONE FINAL SHORT
BURST OF CONVECTION TO OCCUR NEAR THE CENTER. FOR THAT REASON...
BRET IS BEING MAINTAINED AS A TROPICAL CYCLONE FOR THE NEXT 12-24
HOURS IN THE OFFICIAL FORECAST. AFTERWARD...HOWEVER...MUCH COOLER
SSTS OF NEAR 22C BENEATH THE CYCLONE SHOULD RESULT IN DISSIPATION
BY 36-48 HOURS. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND IS A LITTLE ABOVE THE SHIPS AND LGEM
INTENSITY FORECASTS.

FORECAST POSITIONS AND MAX WINDS
 
INIT  22/0900Z 36.7N  66.5W   30 KT  35 MPH
 12H  22/1800Z 38.0N  63.6W   30 KT  35 MPH
 24H  23/0600Z 39.4N  59.5W   25 KT  30 MPH
 36H  23/1800Z 40.9N  54.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
 48H  24/0600Z...DISSIPATED
 
$$
FORECASTER STEWART
 

