[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 130301
TCDAT1
TROPICAL STORM ALBERTO DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012006
1100 PM EDT MON JUN 12 2006

AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT MEASURED 68-KT WINDS AT
700 MB IN THE NORTHEAST QUADRANT JUST NORTHWEST OF CEDAR KEY
FLORDIA... WHICH WAS IN AN AREA OF 64+ KT DOPPELR VELOCITY DATA
FROM TAMPA BAY AND TALLAHASSEE. THESE WIND REPORTS WERE IN AREAS OF
CONVECTIVE BANDING WITH REFLECTIVITIES OF AT LEAST 40 DBZ...SO
USING A 90 PERCENT REDUCTION FACTOR SEEMS APPROPROPRIATE...WHICH
MEANS THAT ALBERTO REMAINS A 60-KT TROPICAL STORM. THE CENTRAL
PRESSURE OF 995 MB IS BASED ON EARLIER RECON DROPSONDE REPORT OF
996 MB WITH A 15-KT SURFACE WIND...AND NOAA BUOY 42036...LOCATED
NORTHEAST OF THE CENTER... REPORTING 997.2 MB PRESSURE AT 13/02Z.

THE INITIAL MOTION ESTIMATE REMAINS 040/09 KT. UPPER-AIR DATA THIS
EVENING INDICATE A NARROW 850-500 MB RIDGE EXTENDING NORTHWESTWARD
AHEAD OF ALBERTO ACROSS SOUTHEASTERN GEORGIA. THIS FEATURE IS
EXPECTED TO NUDGE THE CYCLONE A LITTLE TO THE LEFT OF ITS CURRENT
MOTION...BEFORE THE BEING TURNED BACK TO THE NORTHEAST AHEAD OF A
DIGGING MID-LEVEL SHORTWAVE CURRENTLY LOCATED ACROSS THE TENNESSEE
AND MISSOURI VALLEYS. THE OFFICIAL FORECAST TRACK REMAINS NEAR THE
RIGHT OR EAST SIDE OF THE MODEL GUIDANCE ENVELOPE...AND IS A LITTRL
FATER THAN THE PREVIOSU ADVISORY AFTER ALBERTO BECOMES
EXTRATROPICAL. IT IS POSSIBLE THAT THE INCREASING NORTHWESTERLY
MID-LEVEL FLOW MAY FORCE THE EXTRATROPICAL LOW CLOSER TO THE
CAROLINA COASTS BY 48 HOURS...RESULTING IN AN OVER WATER
EXTRATROPICAL GALE AREA.

SOME SHALLOW CONVECTION HAS BEEN DEVELOPING AROUND THE LOW-LEVEL
CENTER DURING THE PAST FEW HOURS. WHILE GULF WATER TEMPERATURES ARE
ONLY AROUND 79-80F AHEAD OF ALBERTO... THE 00Z UPPER-AIR SOUNDING
FROM TAMPA INDICATES THAT THE ATMOPSHERE AHEAD OF THE CYCLONE AHS
BECOME MORE UNSTABLE SINCE 12Z THIS MORNING. SINCE THERE IS
AVAILABLE INSTABOLILY TO SUPPORT THE REGENERATION OF SIGNIFICANT
CONVECTION LATER TONIGHT AND TUESDAY MORNING... A FORECAST OF
ALBERTO POSSIBLY REACHING HURRICANE STRENGTH BEFORE LANDFALL
APPEARS TO STILL BE IN ORDER.

IN ADDITION TO HEAVY RAINS...THE MAIN HAZARD ASSOCIATED WITH
ALBERTO WILL LIKELY BE STORM SURGE FLOODING...WHICH COULD BE 8-10
FEET ABOVE NORMAL TIDE LEVELS EVEN FOR A STRONG TROPICAL STORM IN
THIS AREA.  IT IS...HOWEVER...IMPOSSIBLE TO SPECIFY EXACTLY WHICH
LOCATIONS WILL EXPERIENCE THE GREATEST STORM SURGE FLOODING BECAUSE
THIS WILL DEPEND UPON THE PRECISE TRACK AND WIND FIELD NEAR
LANDFALL.

FORECASTER STEWART

FORECAST POSITIONS AND MAX WINDS

INITIAL      13/0300Z 28.4N  84.6W    60 KT
 12HR VT     13/1200Z 29.5N  83.7W    65 KT
 24HR VT     14/0000Z 31.1N  82.5W    40 KT...INLAND
 36HR VT     14/1200Z 33.1N  80.6W    30 KT...INLAND
 48HR VT     15/0000Z 35.0N  77.2W    30 KT...INLAND
 72HR VT     16/0000Z 39.5N  68.0W    40 KT...EXTRATROPICAL
 96HR VT     17/0000Z 44.0N  60.0W    40 KT...EXTRATROPICAL
120HR VT     18/0000Z 49.5N  50.0W    40 KT...EXTRATROPICAL


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