545 
 WTNT42 KNHC 070234
 TCDAT2
 TROPICAL STORM BERTHA DISCUSSION NUMBER  16
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
 1100 PM EDT SUN JUL 06 2008
  
 THE SATELLITE PRESENTATION HAS GRADUALLY IMPROVED DURING THE PAST
 SEVERAL HOURS. THE CONVECTION IS SYMMETRIC ABOUT THE CENTER WHILE
 THE OUTFLOW HAS BEEN EXPANDING WESTWARD...TYPICAL OF AN
 INTENSIFYING CYCLONE. FURTHERMORE...CONSECUTIVE MICROWAVE DATA SHOW
 A WELL DEFINED RING OF DEEP CONVECTION...OR EYE-LIKE FEATURE...
 WHICH IS GRADUALLY BECOMING ALIGNED VERTICALLY.  THIS COULD
 EVENTUALLY BE THE PRECURSOR OF AN EYE FORMATION.  DVORAK T-NUMBERS
 HAVE INCREASED AND NOW SUPPORT AN INITIAL INTENSITY OF 55 KNOTS. 
 THE OCEAN IS PLENTY WARM AHEAD OF BERTHA SO THE SHEAR WILL BE THE
 MAIN PRIMARY LARGE SCALE FACTOR CONTROLLING THE FUTURE INTENSITY.
 WE ARE NOT CONSIDERING EYEWALL CYCLES AT THIS TIME...IN CASE AN EYE
 FORMS.  BECAUSE THE SHEAR IS EXPECTED TO BE WEAK FOR THE NEXT DAY
 OR TWO... STRENGTHENING IS INDICATED AND BERTHA COULD BECOME A
 HURRICANE ON MONDAY. THEREAFTER...THE SHEAR IS EXPECTED TO
 FLUCTUATE SO NO IMPORTANT CHANGES IN INTENSITY ARE FORECAST. 
 
 THE CENTER IS A LITTLE FARTHER NORTH AS IT APPEARS TO BE REALIGNING
 WITH THE MID-LEVEL VORTEX. THIS IS NOT A CHANGE IN TRACK SINCE 
 BERTHA IS STILL MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT
 17 KNOTS.  A WEAKNESS OF THE SUBTROPICAL RIDGE ALONG 50 TO 55
 DEGREES WEST WILL PROBABLY CAUSE BERTHA TO BEGIN TO SLOW DOWN SOON. 
 THE SUBTROPICAL RIDGE IS EXPECTED TO REBUILD SOME IN A DAY OR TWO
 CAUSING BERTHA TO CONTINUE ON A WEST-NORTHWEST TO NORTHWEST TRACK.
 BY THE END OF THE FORECAST PERIOD...THE STEERING CURRENTS ARE
 FORECAST TO WEAKEN AGAIN AND BERTHA SHOULD SLOW DOWN CONSIDERABLY
 AS INDICATED BY SOME GLOBAL MODELS. THE OFFICIAL FORECAST IS
 CONSISTENT WITH MOST OF THE TRACK GUIDANCE WHICH IS IN MUCH BETTER
 AGREEMENT TONIGHT. NO NEED TO DISCUSS EVERY MODEL. 
 
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      07/0300Z 18.6N  48.9W    55 KT
  12HR VT     07/1200Z 19.3N  51.5W    60 KT
  24HR VT     08/0000Z 20.0N  54.5W    70 KT
  36HR VT     08/1200Z 21.0N  57.0W    70 KT
  48HR VT     09/0000Z 22.0N  59.5W    70 KT
  72HR VT     10/0000Z 24.0N  62.0W    70 KT
  96HR VT     11/0000Z 27.0N  64.5W    70 KT
 120HR VT     12/0000Z 30.0N  65.5W    70 KT
  
 $$
 FORECASTER AVILA
  
 

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