Hurricane BERTHA

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HURRICANE BERTHA DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
1100 AM EDT FRI JUL 11 2008
 
MICROWAVE DATA CONTINUES TO SHOW A SMALL FRAGMENT OF THE INNER
EYEWALL WITHIN A BETTER DEFINED AND LARGER RING OF CONVECTION
ASSOCIATED WITH THE OUTER EYEWALL.  CONVENTIONAL VIS/IR IMAGES SHOW
THAT BERTHA'S CLOUD PATTERN HAS CHANGED LITTLE WITH GOOD OUTFLOW IN
ALL QUADRANTS. DVORAK T-NUMBERS STILL SUGGEST AN INITIAL INTENSITY
OF 75 KNOTS. THE FIRST RECONNAISSANCE MISSION INTO BERTHA WILL BE
LATER TODAY...SO I WILL BE MORE CONFIDENT WITH THE INITIAL
INTENSITY WHEN THE PLANE GETS THERE. THE CURRENT CLOUD PATTERN
CONFIGURATION...ANNULAR TYPE...AND LOW SHEAR SUGGEST THAT THE
INTENSITY WILL NOT CHANGE IN THE NEXT DAY OR SO. THEREFORE...BERTHA
IS KEPT AT 75 KNOTS UNTIL SHEAR INCREASES AND MOVES OVER A COOLER
OCEAN. THEN...A GRADUAL WEAKENING IS INDICATED. ALTHOUGH IT APPEARS
THAT THE OUTER EYEWALL COULD SHRINK RESULTING IN INTENSIFICATION...
I AM NOT CONSIDERING IT IN THIS FORECAST BECAUSE I HAVE NO IDEA
WHEN OR IF THIS CYCLE WILL OCCUR.
 
BERTHA IS MOVING VERY SLOWLY...AS ANTICIPATED...TOWARD THE NORTHWEST
OR 320 DEGREES AT 5 KNOTS IN BETWEEN A SMALL SUBTROPICAL RIDGE AND
AN APPROACHING SHORTWAVE TROUGH. THIS PATTERN SHOULD KEEP BERTHA
WITHIN VERY WEAK STEERING CURRENTS FOR THE NEXT 2 OR 3 DAYS.
BERTHA IS EXPECTED TO TURN MORE TO THE NORTH AND EVENTUALLY MORE TO
THE NORTH-NORTHEAST. THIS WILL BE VERY SLOW AND BERTHA IS NOT
EXPECTED TO MOVE MORE THAN 300 N MI IN THREE DAYS. THIS IS
CONSISTENT WITH LATEST GUIDANCE WHICH SHOWS THE CORE OF BERTHA
MOVING WELL EAST OF BERMUDA BUT TROPICAL STORM FORCE WINDS EXTEND
FARTHER OUT AND COULD REACH THE ISLAND AND ADJACENT WATERS.
THEREFORE...GIVEN UNCERTAINTIES IN THE FORECASTS OF
BERTHA'S...TRACK... INTENSITY...AND SIZE...THE WEATHER SERVICE OF
BERMUDA HAS ISSUED A TROPICAL STORM WATCH FOR BERMUDA.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1500Z 28.5N  62.0W    75 KT
 12HR VT     12/0000Z 29.2N  62.5W    75 KT
 24HR VT     12/1200Z 30.2N  62.6W    75 KT
 36HR VT     13/0000Z 30.8N  62.2W    75 KT
 48HR VT     13/1200Z 31.5N  61.5W    70 KT
 72HR VT     14/1200Z 32.5N  60.5W    65 KT
 96HR VT     15/1200Z 34.5N  59.5W    60 KT
120HR VT     16/1200Z 37.0N  58.5W    55 KT
 
$$
FORECASTER AVILA
 
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