[Tropical] Tropical Cyclone Discussion

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WTNT41 KNHC 221452
TCDAT1
TROPICAL DEPRESSION SIX DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL062010
1100 AM AST SUN AUG 22 2010

THE UPWARD TREND IN ORGANIZATION OF THE DEPRESSION APPEARS TO HAVE
STOPPED FOR THE TIME BEING.  THE SYSTEM HAS A WELL-DEFINED
CENTER...BUT THE CIRCULATION IS A LITTLE STRETCHED FROM NORTHEAST
TO SOUTHWEST DUE TO ANOTHER DISTURBANCE LOCATED ABOUT 350 N MI TO
THE NORTHEAST.  THIS HAS ALSO CAUSED THE CENTER TO MOVE ALMOST DUE
NORTH OVER THE PAST FEW HOURS...PULLING IT FARTHER AWAY FROM THE
DEEP CONVECTION.  SATELLITE INTENSITY ESTIMATES ARE 30 KT AND 45 KT
FROM SAB AND TAFB...RESPECTIVELY...AND AN 1134 UTC ASCAT PASS
SHOWED A MAXIMUM OF 30 KT.  THE INITIAL INTENSITY WILL BE KEPT AT 30
KT SINCE THERE HAS BEEN LITTLE CHANGE IN ORGANIZATION.

WITH THE RECENT NORTHWARD MOTION...THE SMOOTHED INITIAL MOTION IS
ROUGHLY 310/10.  ONCE THE DEPRESSION ESCAPES THE INFLUENCE OF THE
DISTURBANCE TO ITS NORTHEAST...THE SUBTROPICAL RIDGE CENTERED ALONG
26N SHOULD STEER THE CYCLONE GENERALLY WEST-NORTHWESTWARD WITH
INCREASING FORWARD SPEED THROUGH THE NEXT 72 HOURS.  BY DAYS 4 AND
5 THERE IS GREATER UNCERTAINTY WITH THE TRACK FORECAST DEPENDING ON
HOW THE MID-LATITUDE LONGWAVE PATTERN EVOLVES IN RELATION TO WHEN
THE DEPRESSION ACTUALLY BEGINS MOVING WESTWARD.  THE GLOBAL MODEL
GUIDANCE IS IN GOOD AGREEMENT SHOWING AN AMPLIFYING TROUGH NEAR 45W
BY DAY 4...WHICH SHOULD BE TOO FAR EAST TO INDUCE SIGNIFICANT
RECURVATURE.  THIS PATTERN...HOWEVER...SHOULD CAUSE THE SYSTEM TO
SLOW DOWN A LITTLE BY DAYS 4 AND 5 AS IT BECOMES TRAPPED TO THE
SOUTH OF A MID-LEVEL RIDGE.  THE OFFICIAL FORECAST HAS BEEN SHIFTED
A LITTLE SOUTH AND WEST BY DAY 5...VERY CLOSE TO THE GFS...GFDL
...AND HWRF MODELS...AND LIES A LITTLE TO THE RIGHT OF THE MODEL
CONSENSUS TVCN.

THE DEPRESSION IS EXPECTED TO REMAIN UNDER THE INFLUENCE OF MODERATE
EAST-NORTHEASTERLY SHEAR FOR THE NEXT 24 HOURS OR SO...BUT
THEREAFTER THE UPPER-LEVEL ENVIRONMENT BECOMES MORE CONDUCIVE FOR
STRENGTHENING.  HOWEVER...THE SYSTEM MAY STILL HAVE TO CONTEND WITH
DRY AND RELATIVELY STABLE AIR TO ITS NORTH AS IT MOVES ACROSS THE
ATLANTIC...AND MOST OF THE INTENSITY GUIDANCE NOW SHOWS A SLOWER
RATE OF INTENSIFICATION.  THE OFFICIAL FORECAST HAS BEEN NUDGED
DOWN A LITTLE FROM THE PREVIOUS FORECAST BUT IS STILL HIGHER THAN
EVERY INTENSITY MODEL AT DAY 5 EXCEPT FOR THE GFDL.  BASED ON AN
EXPERIMENTAL INTENSITY PROBABILITY PRODUCT AT NHC...THE DEPRESSION
CURRENTLY HAS A 1 IN 5 CHANCE OF REACHING MAJOR HURRICANE STATUS AT
SOME POINT OVER THE NEXT FIVE DAYS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      22/1500Z 12.7N  34.1W    30 KT
 12HR VT     23/0000Z 13.0N  35.6W    35 KT
 24HR VT     23/1200Z 13.8N  38.1W    40 KT
 36HR VT     24/0000Z 14.7N  40.8W    50 KT
 48HR VT     24/1200Z 15.9N  43.7W    60 KT
 72HR VT     25/1200Z 19.0N  49.0W    70 KT
 96HR VT     26/1200Z 22.0N  53.0W    80 KT
120HR VT     27/1200Z 24.5N  56.0W    85 KT

$$
FORECASTER BERG


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