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Hurricane DARBY


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HURRICANE DARBY DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 PM PDT SAT JUN 26 2010

EARLIER THIS AFTERNOON...THE CIRCULATION CENTER OF DARBY BECAME
PARTIALLY EXPOSED TO THE EAST OF THE CENTRAL DENSE OVERCAST....
APPARENTLY DUE TO INCREASING EASTERLY SHEAR. SINCE THAT TIME...A
NEW BURST OF DEEP CONVECTION HAS DEVELOPED NEAR THE CENTER...BUT
THIS NEW CONVECTIVE ACTIVITY COULD BE TEMPORARY. DVORAK SATELLITE
CURRENT INTENSITY ESTIMATES ARE 85 KT FROM TAFB AND 95 KT FROM
SAB...BUT THEY ARE CONSTRAINED DUE TO RULES. THE CIMSS ADT AT 1745
UTC WAS 75 KT...WHICH SEEMS MUCH MORE REASONABLE SINCE SMALL...
COMPACT TROPICAL CYCLONES WEAKEN MORE RAPIDLY THAN A NORMAL
CLIMATOLOGICAL RATE. THEREFORE...THE INITIAL INTENSITY IS LOWERED
TO 75 KT. THE EASTERLY SHEAR SHOULD STRENGTHEN THROUGH THE
REMAINDER OF THE FORECAST...RESULTING IN FURTHER WEAKENING. THE
OFFICIAL INTENSITY FORECAST IS BASED ON THE SHIPS MODEL WHICH
INDICATES A QUICKER WEAKENING TREND. 

THE INITIAL MOTION ESTIMATE IS A DRIFT OR 260/2...WITHIN THE
EASTERLY MID- TO UPPER-TROPOSPHERIC STEERING FLOW OF A WEAKENING
MID-LEVEL RIDGE EXTENDING WESTWARD OVER THE EASTERN TROPICAL
PACIFIC FROM MEXICO. LARGE-SCALE MODELS CONTINUE TO SUGGEST THAT
THE AFOREMENTIONED RIDGE WILL WEAKEN FURTHER DURING THE NEXT DAY OR
SO...ALLOWING DARBY TO MAINTAIN A SLOW...AND POSSIBLY ERRATIC...
WESTWARD MOTION. AFTERWARD...THE CYCLONE OR ITS REMNANTS SHOULD
GRADUALLY TURN NORTHEASTWARD AND CONTINUE ON THIS HEADING THROUGH
DAY 5. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY
WHICH CLOSELY FOLLOWS THE TVCN MULTI-MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/2100Z 13.4N 102.8W    75 KT
 12HR VT     27/0600Z 13.4N 103.2W    65 KT
 24HR VT     27/1800Z 13.5N 103.6W    60 KT
 36HR VT     28/0600Z 13.8N 103.5W    55 KT
 48HR VT     28/1800Z 14.2N 103.1W    50 KT
 72HR VT     29/1800Z 14.5N 102.4W    40 KT
 96HR VT     30/1800Z 14.9N 101.9W    35 KT
120HR VT     01/1800Z 15.2N 101.7W    30 KT
 
$$
FORECASTER ROBERTS/AVILA
 
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