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Tropical Storm FERNANDA (Text)

ZCZC MIATCDEP1 ALL
TTAA00 KNHC DDHHMM CCA
 
TROPICAL STORM FERNANDA DISCUSSION NUMBER   9...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP062011
200 PM PDT WED AUG 17 2011

CORRECTED TYPO IN SECOND PARAGRAPH AND STATUS IN TABLE AT 72H
 
ALTHOUGH THE CONVECTION IN FERNANDA HAS STAGED A COMEBACK DURING
THE LAST SEVERAL HOURS...THE OVERALL DEPTH OF THE CONVECTION IS
RELATIVELY SHALLOW.  MICROWAVE IMAGERY STILL INDICATES THAT THE
CYCLONE IS MAINTAINING A WELL ORGANIZED LOW-LEVEL STRUCTURE...WITH
AN EYE-LIKE FEATURE AND PLENTY OF CURVED BANDS. SATELLITE
INTENSITY ESTIMATES ARE ESSENTIALLY UNCHANGED SINCE THIS MORNING...
AND THE INITIAL INTENSITY ESTIMATE IS THEREFORE HELD AT 45 KT.
 
FERNANDA HAS BEGUN MOVING ON A WEST-NORTHWESTWARD HEADING...AND THE
INITIAL MOTION ESTIMATE IS NOW 290/07. THE CYCLONE APPEARS TO BE
RESPONDING TO A WEAKNESS IN THE MID-LEVEL SUBTROPICAL RIDGE THAT HAS
FORMED IN RESPONSE TO A LONGWAVE TROUGH NOW SLOWLY LIFTING OUT
ALONG 140W.  THE CURRENT SYNOPTIC PATTERN WILL CAUSE FERNANDA TO
CONTINUE A WEST-NORTHWESTWARD MOTION FOR THE NEXT 48-72 HOURS. A
TURN TOWARD THE WEST SHOULD OCCUR LATER IN THE FORECAST PERIOD ONCE
FERNANDA WEAKENS AND BECOMES A MORE SHALLOW SYSTEM. THE FORECAST
GUIDANCE HAS COME INTO BETTER AGREEMENT ON THIS SCENARIO SINCE THE
PREVIOUS CYCLE...AND THE OFFICIAL NHC FORECAST IS LARGELY UNCHANGED
FROM THE PREVIOUS ONE.
 
ALTHOUGH FERNANDA REMAINS IN A LOW SHEAR ENVIRONMENT...IT HAS
ALREADY BEGUN TO MOVE OVER MARGINALLY WARM WATERS.  THE PROXIMITY
OF THE NEARBY STRATOCUMULUS FIELD SUGGESTS THAT THE CYCLONE MAY ALSO
BE TAPPING A DRIER AND MORE STABLE AIR MASS.  THIS MARGINAL
THERMODYNAMIC ENVIRONMENT SHOULD LIMIT ANY SIGNIFICANT
STRENGTHENING DURING THE NEXT 24 HOURS.  THE GREATER POLEWARD
COMPONENT OF MOTION THE STORM IS NOW EXPERIENCING SHOULD BRING THE
STORM OVER EVEN COOLER WATERS AFTER 24 HOURS...AND STEADY WEAKENING
IS FORECAST TO BEGIN BY THEN.  THE EFFECTS OF INCREASING SHEAR AND
NEAR 25C WATERS AFTER 48 HOURS COULD RESULT IN A RATHER RAPID
DEMISE.  THE OFFICIAL NHC FORECAST IS NUDGED DOWNWARD...AT THE
LOW END OF THE INTENSITY GUIDANCE...WITH POST-TROPICAL STATUS NOW
FORECAST SOONER. 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  17/2100Z 12.1N 138.2W   45 KT  50 MPH
 12H  18/0600Z 12.8N 139.5W   50 KT  60 MPH
 24H  18/1800Z 13.6N 141.1W   45 KT  50 MPH
 36H  19/0600Z 14.4N 142.8W   35 KT  40 MPH
 48H  19/1800Z 15.1N 144.7W   30 KT  35 MPH
 72H  20/1800Z 16.0N 148.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
 96H  21/1800Z 16.6N 153.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  22/1800Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN
 
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