[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 250838
TCDAT1
HURRICANE DANIELLE DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
500 AM AST WED AUG 25 2010

ALTHOUGH THE CLOUD PATTERN OF THE HURRICANE HAS NOT BECOME MUCH
BETTER ORGANIZED ON GEOSTATIONARY IMAGERY...AN AMSR-E PASS FROM
0516 UTC SUGGESTS AN EYE WITH FAIRLY WELL-DEFINED INNER CORE
CONVECTIVE BANDING ON THE 37-GHZ CHANNEL.  CIRRUS-LEVEL OUTFLOW IS
BECOMING A LITTLE BETTER DEFINED TO THE NORTHWEST.  USING A BLEND
OF DVORAK CURRENT INTENSITY ESTIMATES FROM TAFB AND SAB...THE
ADVISORY INTENSITY IS SET TO 70 KT.  AN UPPER-LEVEL CYCLONE TO THE
NORTH-NORTHWEST OF THE HURRICANE HAS BEEN IMPARTING MODERATE
WEST-SOUTHWESTERLY SHEAR ON DANIELLE.  GLOBAL MODEL GUIDANCE
INDICATES THAT THIS UPPER-LEVEL CYCLONE SHOULD MOVE SOUTHWEST OVER
THE NEXT 24 TO 48 HOURS.  THIS EVOLUTION WOULD CAUSE THE SHEAR TO
WEAKEN AND BECOME MORE SOUTHERLY OR EVEN SOUTHEASTERLY.  BOTH OF
THESE ENVIRONMENTAL FACTORS SHOULD BE MORE CONDUCIVE FOR
STRENGTHENING.  NEAR THE END OF THE FORECAST PERIOD...DYNAMICAL
GUIDANCE SHOWS A SIGNIFICANT INCREASE IN SHEAR SO THE HURRICANE
WILL PROBABLY BE ON A WEAKENING TREND BY DAY 5.  THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE NUMERICAL INTENSITY CONSENSUS.

THERE HAS BEEN A GRADUAL DECREASE IN FORWARD SPEED AND THE INITIAL
MOTION IS NOW ESTIMATED TO BE ABOUT 300/15.  A TURN TOWARD THE
NORTHWEST IS LIKELY TO OCCUR VERY SOON IN RESPONSE TO A WEAKNESS IN
THE SUBTROPICAL RIDGE TO THE NORTH OF DANIEL.  A SHORT WAVE
MID-TROPOSPHERIC RIDGE WILL BE PASSING TO THE NORTH OF THE
HURRICANE IN A COUPLE OF DAYS.  THIS WOULD TEMPORARILY HALT A
FURTHER TURN TO THE RIGHT...UNTIL THE RIDGE MOVES FARTHER EAST.
LATER ON...A MORE NORTHWARD MOTION IS LIKELY AS DANIELLE MOVES
AROUND THE WESTERN PERIPHERY OF THE RIDGE AND IS INFLUENCED BY A
TROUGH MOVING OFF THE NORTHEAST U.S. COAST.  THE OFFICIAL TRACK
FORECAST IS QUITE CLOSE TO THE DYNAMICAL MODEL CONSENSUS.  IT
SHOULD BE NOTED THAT THE LATEST ECMWF FORECAST IS AN OUTLIER...
SHOWING A SHARPER TURN TO THE RIGHT THAN MOST OF THE MODELS...AND
IS SIGNIFICANTLY FASTER THAN THE OTHER TRACK GUIDANCE.  IT WILL BE
INTERESTING TO SEE IF THAT MODEL TURNS OUT TO BE CORRECT.

FORECAST POSITIONS AND MAX WINDS

INITIAL      25/0900Z 18.8N  51.0W    75 KT
 12HR VT     25/1800Z 20.1N  52.7W    70 KT
 24HR VT     26/0600Z 21.8N  54.5W    70 KT
 36HR VT     26/1800Z 23.3N  56.3W    75 KT
 48HR VT     27/0600Z 24.5N  58.0W    80 KT
 72HR VT     28/0600Z 27.0N  61.0W    90 KT
 96HR VT     29/0600Z 30.0N  62.0W    95 KT
120HR VT     30/0600Z 33.0N  62.0W    85 KT

$$
FORECASTER PASCH


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