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Tropical Storm BERTHA (Text)

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TROPICAL STORM BERTHA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT SUN JUL 06 2008
 
A COUPLE OF MICROWAVE IMAGES JUST RECEIVED SUGGEST THAT BERTHA'S
VORTEX IS TILTED A LITTLE.  THE IMAGES INDICATE THAT THE
LOW-LEVEL CENTER IS LOCATED JUST SOUTHWEST OF THE MID-LEVEL CENTER.
HOWEVER...THESE IMAGES ALSO SUGGEST THAT THE OVERALL STRUCTURE HAS
IMPROVED WITH THE APPEARANCE OF AN EYE FEATURE...SUGGESTING THAT
BERTHA IS STRENGTHENING.  DVORAK INTENSITY ESTIMATES WERE 45 KT AT
18Z...BUT WITH THE IMPROVING STRUCTURE THE INITIAL INTENSITY IS
INCREASED TO 50 KT. CONDITIONS APPEAR CONDUCIVE FOR STRENGTHENING
DURING THE NEXT COUPLE OF DAYS AND BERTHA COULD BECOME A HURRICANE. 
HOWEVER...INDICATIONS ARE THAT BEYOND 48 HOURS...WESTERLY SHEAR
COULD HALT ANY ADDITIONAL STRENGTHENING AS SUGGESTED BY THE SHIPS
MODELS.
 
BERTHA IS MOVING WEST-NORTHWESTWARD OR 285/17 KT.  ALL OF THE
AVAILABLE GUIDANCE SHOWS A NORTHWEST TURN AS THE RIDGE OVER THE
WESTERN ATLANTIC WEAKENS IN A FEW DAYS. HOWEVER...THERE REMAINS
SOME SPREAD IN THE GUIDANCE AS TO WHEN THE TURN OCCURS.  THE HWRF
AND GFDL...WHICH DEPICT A STRONG TROPICAL CYCLONE REMAINS ALONG
THE EASTERN EDGE OF THE MODEL ENVELOPE.  THE UKMET WHICH KEEPS
BERTHA WEAKER IS ALONG THE WESTERN EDGE. THE NEW TRACK
FORECAST IS ADJUSTED SLIGHTLY EASTWARD...BUT STILL REMAINS
WEST OF THE MODEL CONSENSUS.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/2100Z 18.1N  47.0W    50 KT
 12HR VT     07/0600Z 18.7N  49.6W    55 KT
 24HR VT     07/1800Z 19.5N  52.3W    60 KT
 36HR VT     08/0600Z 20.2N  54.6W    65 KT
 48HR VT     08/1800Z 20.9N  56.7W    70 KT
 72HR VT     09/1800Z 23.0N  60.5W    70 KT
 96HR VT     10/1800Z 26.0N  64.0W    70 KT
120HR VT     11/1800Z 29.0N  65.5W    70 KT
 
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FORECASTER BROWN
 
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