TROPICAL STORM ARLENE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
1000 PM CDT TUE JUN 28 2011

WHILE THE DEEP CONVECTION NEAR AND TO THE NORTHEAST OF THE CENTER OF
ARLENE HAS CONTINUED TO INCREASE DURING THE LAST FEW HOURS...THERE
HAS BEEN NO FURTHER INCREASE IN ITS ORGANIZATION.  DVORAK SATELLITE
INTENSITY ESTIMATES REMAIN UNCHANGED SINCE 0000 UTC...AND THE
INITIAL INTENSITY IS HELD AT 35 KT.  

SATELLITE IMAGERY SUGGESTS THAT UPPER-LEVEL WESTERLY WINDS CONTINUE
TO IMPINGE ON THE CYCLONE...AND UW CIMSS SHEAR ANALYSES INDICATE
ABOUT 20 KT OF WESTERLY SHEAR AFFECTING ARLENE. THE DYNAMICAL MODEL
AND SHIPS GUIDANCE SUGGEST THAT THE SHEAR WILL DECREASE DURING THE
NEXT 24 HOURS WHICH SHOULD ALLOW AN OPPORTUNITY FOR GRADUAL
STRENGTHENING. HOWEVER...THE LARGE CIRCULATION OF THE TROPICAL
CYCLONE AND THE POSSIBILITY OF A SLOWER REDUCTION OF THE WESTERLY
SHEAR COULD LIMIT ITS POTENTIAL FOR SIGNIFICANT INTENSIFICATION
PRIOR TO LANDFALL.   THE OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND CLOSE TO CONSENSUS OF THE INTENSITY GUIDANCE. 

ARLENE CONTINUES MOVING SLOWLY WEST-NORTHWESTWARD OR 295/6. THE
STORM IS FORECAST TO TURN TOWARD THE WEST ON WEDNESDAY AS A MID- TO
UPPER-LEVEL RIDGE OVER THE CENTRAL UNITED STATES BUILDS EASTWARD. 
SEVERAL OF THE DYNAMICAL MODELS INDICATE THAT ARLENE COULD TURN
WEST-SOUTHWESTWARD AS IT APPROACHES THE COAST OF MEXICO DUE TO THE
STRENGTHENING RIDGE.  THE OFFICIAL TRACK FORECAST SUGGESTS THIS
POSSIBILITY AND LIES BETWEEN THE GFS AND ECMWF MODEL SOLUTIONS. 

GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT
FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS COULD BE FELT OVER A
LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE CENTER.

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