019 
 WTNT42 KNHC 050234
 TCDAT2
 TROPICAL STORM BERTHA DISCUSSION NUMBER   8
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
 1100 PM EDT FRI JUL 04 2008
 
 MICROWAVE IMAGERY OVER THE LAST 12-24 HOURS INDICATES THAT BERTHA
 HAS BEEN STAIR-STEPPING ITS WAY ACROSS THE ATLANTIC OSCILLATING
 BETWEEN A WESTWARD AND NORTHWESTWARD HEADING WITH EACH NEW
 CONVECTIVE BURST.  IRONING ALL THIS OUT YIELDS AN INITIAL MOTION
 ESTIMATE OF 280/18...A LITTLE FASTER THAN BEFORE.  THERE HAS BEEN
 LITTLE OVERALL CHANGE IN THE FORECAST PHILOSOPHY.  A STRONG RIDGE
 TO THE NORTH SHOULD KEEP THE CYCLONE ON A GENERAL WESTWARD TO WEST-
 NORTHWESTWARD MOTION DURING THE NEXT 2-3 DAYS.  WHILE MOST OF THE
 DYNAMICAL MODELS STILL SHOW A WEAKNESS DEVELOPING IN THE RIDGE
 NORTH OF BERTHA IN ABOUT THREE DAYS...THEY HAVE BEEN TRENDING
 TOWARDS A MORE WESTWARD MOTION OF BERTHA DUE TO A WEAKER AND
 SHALLOWER DEPICTION OF THE CYCLONE.  THE EXCEPTION IS THE HWRF
 WHICH FORECASTS A STRONGER AND DEEPER BERTHA TURNING NORTHWESTWARD
 BEYOND 72 HOURS DUE TO THE WEAKNESS.  THE OFFICIAL FORECAST IS
 NUDGED A LITTLE WESTWARD BUT IS STILL NORTH OF MOST OF THE GUIDANCE
 SINCE ONLY A MODEST INCREASE IN STRENGTH WOULD ALLOW BERTHA TO
 RESPOND TO THE DEEPER AND MORE NORTHWARD STEERING.    
  
 BERTHA CONTINUES TO EXHIBIT A CONVECTIVE BURSTING PATTERN WITH THE
 LATEST BURST BEGINNING AROUND 2300 UTC.  AVAILABLE SATELLITE
 INTENSITY ESTIMATES SUGGEST THAT THE SYSTEM HAS CHANGED LITTLE IN
 STRENGTH WITH THE INITIAL INTENSITY HELD AT 45 KT. BERTHA IS
 FORECAST TO MOVE OVER MARGINALLY WARM SSTS DURING THE NEXT 24 HOURS
 WHICH IS EXPECTED TO LIMIT INTENSIFICATION.  THEREAFTER...SSTS
 GRADUALLY INCREASE ALONG THE PROJECTED TRACK AND BERTHA IS EXPECTED
 TO SLOWLY STRENGTHEN.  VERTICAL SHEAR IS FORECAST TO INCREASE
 TOWARDS THE END OF THE FORECAST SO ARRESTED DEVELOPMENT IS SHOWN
 BEYOND 72 HOURS.  THIS FORECAST IS SIMILAR TO THE PREVIOUS ONE AND
 IS IN CLOSEST AGREEMENT WITH THE HWRF MODEL. 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      05/0300Z 16.0N  33.5W    45 KT
  12HR VT     05/1200Z 16.4N  36.2W    45 KT
  24HR VT     06/0000Z 17.0N  39.8W    45 KT
  36HR VT     06/1200Z 17.6N  43.6W    50 KT
  48HR VT     07/0000Z 18.1N  47.3W    55 KT
  72HR VT     08/0000Z 20.0N  53.5W    60 KT
  96HR VT     09/0000Z 22.0N  58.5W    60 KT
 120HR VT     10/0000Z 24.0N  63.0W    60 KT
  
 $$
 FORECASTER RHOME
  
 
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