599 
 WTNT42 KNHC 060234
 TCDAT2
 TROPICAL STORM BERTHA DISCUSSION NUMBER  12
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
 1100 PM EDT SAT JUL 05 2008
  
 LATEST SATELLITE IMAGERY INDICATES THAT BERTHA CONTINUES TO EXHIBIT
 A CONVECTIVE BURSTING PATTERN WITH THE CENTER CURRENTLY LOCATED
 NEAR THE SOUTH SIDE OF THE COLDEST CLOUD TOPS. DVORAK INTENSITY
 ESTIMATES ARE UNCHANGED AND SO IS THE INITIAL INTENSITY...45 KT.
 BERTHA IS BEGINNING TO ENCOUNTER WARMER WATERS AND THE CYCLONE IS
 EXPECTED TO REACH THE 27 DEGREE CELSIUS ISOTHERM IN 36-48 HOURS.
 SINCE THE SHEAR IS EXPECTED TO BE LIGHT DURING THIS PERIOD...SLOW
 STRENGTHENING IS EXPECTED. THE FORECAST BECOMES MORE UNCERTAIN
 BEYOND 48 HOURS DUE TO SPREAD IN THE TRACK MODELS AND THE RESULTING
 DIFFERENCES IN THE ATMOSPHERIC CONDITIONS BERTHA MIGHT EXPERIENCE.
 A TRACK MORE TOWARDS THE NORTH WOULD ALLOW MORE STRENGTHENING WHILE
 A TRACK MORE TOWARDS THE WEST WOULD RESULT IN INCREASING VERTICAL
 SHEAR. SINCE THE OFFICIAL TRACK FORECAST TAKES BERTHA INTO AN AREA
 WITH MODERATE VERTICAL SHEAR...ARRESTED DEVELOPMENT IS FORECAST
 BEYOND 72 HOURS. THIS NEW OFFICIAL FORECAST IS CONSISTENT WITH THE
 PREVIOUS FORECAST BUT SLIGHTLY LOWER THAN THE CONSENSUS OF THE
 AVAILABLE INTENSITY MODELS. 
  
 BERTHA CONTINUES TO MOVE RAPIDLY WESTWARD WITH AN INITIAL MOTION OF
 280/18. THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT
 36-48 HOURS COURTESY OF A STRONG RIDGE TO THE NORTH.  THEREAFTER...
 THE CYCLONE BEGINS TO ENCOUNTER A WEAKNESS IN THE SUBTROPICAL RIDGE
 AND TRACK MODELS DIVERGE SIGNIFICANTLY.  IN FACT...THE SPREAD IN
 THE TRACK MODELS SPAN NEARLY 1300 MILES AT DAY 5 WITH THE UKMET
 MODEL KEEPING BERTHA HEADED WESTWARD AND THE HWRF TURNING THE
 CYCLONE NORTHWARD.  GIVEN THE UNCERTAINTY...THE OFFICIAL FORECAST
 IS SIMILAR TO THE PREVIOUS FORECAST AND LIES IN THE MIDDLE OF THE
 TRACK MODEL ENVELOPE.   
  
 IT SHOULD BE NOTED THAT THERE IS LARGER THAN NORMAL UNCERTAINTY IN
 BOTH THE TRACK AND INTENSITY FORECASTS OF BERTHA.  ACCORDINGLY...IT
 IS MUCH TOO EARLY TO DETERMINE IF BERTHA WILL OR WILL NOT POSE A
 THREAT TO ANY LAND AREAS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      06/0300Z 17.0N  41.2W    45 KT
  12HR VT     06/1200Z 17.4N  44.0W    45 KT
  24HR VT     07/0000Z 18.1N  47.6W    50 KT
  36HR VT     07/1200Z 18.9N  51.0W    55 KT
  48HR VT     08/0000Z 19.6N  53.7W    60 KT
  72HR VT     09/0000Z 21.5N  59.0W    65 KT
  96HR VT     10/0000Z 23.5N  63.5W    65 KT
 120HR VT     11/0000Z 26.0N  67.5W    65 KT
  
 $$
 FORECASTER RHOME
  
 
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