Hurricane HENRIETTE
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HURRICANE HENRIETTE DISCUSSION NUMBER 18
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082013
200 PM PDT WED AUG 07 2013
THE CLOUD PATTERN OF HENRIETTE HAS CHANGED A LITTLE DURING THE PAST
6 HOURS. AN EYE IS TRYING TO APPEAR IN THE MIDDLE OF THE CENTRAL
DENSE OVERCAST...WHILE AN APPARENT DRY SLOT IS WRAPPING BETWEEN THE
CDO AND THE OUTER BANDING IN THE EASTERN SEMICIRCLE. SATELLITE
INTENSITY ESTIMATES REMAIN 77 KT FROM TAFB AND SAB...AND THERE WAS
A 70 KT AMSU INTENSITY ESTIMATE FROM CIMSS A FEW HOURS AGO. BASED
ON THESE DATA...THE INITIAL INTENSITY REMAINS 75 KT.
THE INITIAL MOTION IS 300/10. THE HURRICANE IS CURRENTLY MOVING
TOWARD A WEAKNESS IN THE SUBTROPICAL RIDGE. HOWEVER...THE
DYNAMICAL MODELS FORECAST TO RIDGE TO BUILD TO THE NORTHWEST OF THE
CYCLONE AFTER 24-36 HOURS. THIS SHOULD CAUSE THE SYSTEM TO TURN
TOWARD THE WEST AND WEST-SOUTHWEST. THE TRACK GUIDANCE IS IN GOOD
AGREEMENT WITH THIS SCENARIO...AND THE GUIDANCE HAS CHANGED LITTLE
SINCE THE LAST ADVISORY. THE NEW FORECAST TRACK IS AN UPDATE OF
THE OLD TRACK AND LIES NEAR THE CENTER OF THE TRACK GUIDANCE
ENVELOPE.
HENRIETTE IS EXPECTED TO MOVE OVER COLDER WATERS AND INTO SOMEWHAT
STRONGER WESTERLY VERTICAL WIND SHEAR DURING THE NEXT 12-48 HOURS.
THIS SHOULD CAUSE THE SYSTEM TO WEAKEN...WITH THE GFS...THE
UKMET...AND THE CANADIAN MODELS FORECASTING THE MID/UPPER-LEVEL
PART OF THE CIRCULATION TO DISSIPATE DURING THIS TIME. THE NEW
INTENSITY FORECAST CALLS FOR A SLIGHTLY FASTER WEAKENING THAN THE
PREVIOUS FORECAST. AFTER 48 HOURS...THE SYSTEM IS EXPECTED TO MOVE
OVER WARMER SEA SURFACE TEMPERATURES AND DECREASED SHEAR.
HOWEVER...THE INTENSITY GUIDANCE CALLS FOR CONTINUED WEAKENING
AFTER 48 HOURS...APPARENTLY DUE TO INCREASED DRY AIR ENTRAINMENT.
THE LATTER PART OF THE INTENSITY FORECAST FOLLOWS THE MODEL
TREND...BUT WITH A SLOWER WEAKENING RATE THAN THE PREVIOUS
ADVISORY.
FORECAST POSITIONS AND MAX WINDS
INIT 07/2100Z 16.7N 135.8W 75 KT 85 MPH
12H 08/0600Z 17.3N 137.2W 70 KT 80 MPH
24H 08/1800Z 17.7N 138.8W 60 KT 70 MPH
36H 09/0600Z 17.6N 140.6W 50 KT 60 MPH
48H 09/1800Z 17.1N 142.7W 45 KT 50 MPH
72H 10/1800Z 16.0N 148.0W 35 KT 40 MPH
96H 11/1800Z 14.5N 154.5W 30 KT 35 MPH
120H 12/1800Z 13.0N 160.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
$$
FORECASTER BEVEN
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