129 
 WTNT42 KNHC 111437
 TCDAT2
 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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