Tropical Storm BARBARA

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TROPICAL STORM BARBARA DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP022013
800 AM PDT WED MAY 29 2013
 
AFTER A SIGNIFICANT INTENSIFICATION EPISODE EARLIER THIS
MORNING...RADAR AND SATELLITE DATA SHOW LITTLE CHANGE IN
ORGANIZATION OVER THE PAST FEW HOURS.  RADAR IMAGERY SUGGESTS A
BANDING-TYPE EYE AS OPPOSED TO A CLOSED EYEWALL.  BASED ON A
COMPARISON OF VISIBLE SATELLITE IMAGERY TO THE PUERTO ANGEL MEXICAN
RADAR IMAGES...THE CENTER IS TILTED SLIGHTLY SOUTHWARD WITH HEIGHT. 
THIS IS CONSISTENT WITH THE MODERATE NORTHERLY VERTICAL SHEAR
DIAGNOSED BY THE NUMERICAL GUIDANCE.  THE CURRENT INTENSITY IS SET
AT 55 KT IN AGREEMENT WITH THE LATEST OBJECTIVE DVORAK ESTIMATES.
THE WINDOW FOR INTENSIFICATION PRIOR TO LANDFALL IS CLOSING...BUT
ENVIRONMENTAL CONDITIONS CONTINUE TO FAVOR STRENGTHENING UNTIL THE
CENTER CROSSES THE COASTLINE. ALTHOUGH NOT EXPLICITLY SHOWN IN THE
WIND SPEED FORECAST...WE STILL ANTICIPATE THAT BARBARA WILL BECOME
A HURRICANE IN A FEW HOURS. WEAKENING SHOULD BE RAPID LATER TODAY
AND TONIGHT AS THE CYCLONE INTERACTS WITH THE MOUNTAINOUS TERRAIN
OF SOUTHEASTERN MEXICO. ALTHOUGH THE CENTER IS FORECAST TO REACH
THE EXTREME SOUTHWEST GULF OF MEXICO WITHIN 36 HOURS...THE CURRENT
THINKING IS THAT THE CIRCULATION WILL HAVE BEEN SO SEVERELY
DISRUPTED BY THAT TIME THAT REGENERATION IS UNLIKELY. THIS IS
SUPPORTED BY THE GLOBAL MODELS...WHICH ALSO SHOW STRONG VERTICAL
SHEAR OVER THE SOUTHWEST GULF.
 
THE FORWARD SPEED HAS INCREASED SUBSTANTIALLY THIS MORNING AND THE
INITIAL MOTION ESTIMATE IS 040/11. THE ACCELERATION APPEARS TO BE
DUE TO A BELT OF MID-LEVEL SOUTHWESTERLIES THAT EXTENDS FROM THE
LOW LATITUDES OF THE EASTERN PACIFIC INTO EXTREME EASTERN MEXICO
AND CENTRAL AMERICA. WHEN THE CYCLONE MOVES OVER THE ISTHMUS OF
TEHUANTEPEC...IT SHOULD ENCOUNTER A WEAKER STEERING CURRENT AS IT
MOVES AWAY FROM THE BELT OF SOUTHWESTERLIES AND APPROACHES A BROAD
RIDGE OVER CENTRAL MEXICO. THE OFFICIAL FORECAST SHOWS A DECREASING
FORWARD SPEED OVER THE NEXT DAY OR SO...WHICH IS IN GOOD AGREEMENT
WITH THE TRACK MODEL CONSENSUS.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 15.7N  94.6W   55 KT  65 MPH
 12H  30/0000Z 16.9N  94.0W   40 KT  45 MPH...INLAND
 24H  30/1200Z 17.9N  93.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  31/0000Z 18.5N  94.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 48H  31/1200Z...DISSIPATED
 
$$
FORECASTER PASCH/LANDSEA
 
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