154 
 WTNT42 KNHC 170837
 TCDAT2
 TROPICAL STORM BERTHA DISCUSSION NUMBER  57
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
 500 AM EDT THU JUL 17 2008
  
 NORTHWESTERLY SHEAR APPEARS TO BE TAKING ITS TOLL ON BERTHA AS THE
 REMAINING THUNDERSTORM ACTIVITY IS LIMITED TO THE EAST AND
 SOUTHEAST OF THE CENTER.  THE LATEST DVORAK INTENSITY ESTIMATES ARE
 45 KT AND A RECENT ASCAT PASS SUGGESTS THAT BERTHA'S WINDS HAVE
 INDEED DECREASED. THE INITIAL INTENSITY IS LOWERED TO PERHAPS A
 GENEROUS 50 KT.  ALTHOUGH BERTHA IS FORECAST TO MOVE OVER SLIGHTLY
 WARMER WATERS TODAY...CONTINUED SHEAR SHOULD MEAN LITTLE CHANGE IN
 INTENSITY.  IN FACT...NO CHANGE IN INTENSITY IS PREDICTED
 THROUGHOUT THE FORECAST PERIOD AND THIS IS IN LINE WITH 
 THE LATEST SHIPS AND LGEM GUIDANCE.
 
 BERTHA IS STILL MOVING SOUTHEASTWARD WITH AN INITIAL MOTION ESTIMATE
 OF 140/9.  WATER VAPOR IMAGERY INDICATES THAT THE UPPER-LEVEL LOW
 IS BEGINNING TO MOVE NORTHWARD AND BERTHA SHOULD TURN EASTWARD 
 AROUND THE SOUTHWESTERN PERIPHERY OF THE LOW DURING THE NEXT 6-12
 HOURS.  THEREAFTER....BERTHA SHOULD GRADUALLY ACCELERATE
 NORTHEASTWARD.  THE NEW FORECAST IS ADJUSTED A LITTLE SOUTH OF THE
 PREVIOUS TRACK DURING THE FIRST 24 HOURS...OTHERWISE IT IS VERY
 SIMILAR TO THE PREVIOUS ADVISORY.  BERTHA SHOULD BECOME
 EXTRATROPICAL IN 3-4 DAYS AND COULD GET ABSORBED BY A LARGER
 EXTRATROPICAL LOW IN ABOUT 5 DAYS.  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      17/0900Z 34.5N  59.2W    50 KT
  12HR VT     17/1800Z 34.0N  58.0W    45 KT
  24HR VT     18/0600Z 34.5N  55.7W    45 KT
  36HR VT     18/1800Z 36.3N  53.2W    45 KT
  48HR VT     19/0600Z 38.4N  50.2W    45 KT
  72HR VT     20/0600Z 43.1N  44.3W    45 KT...BECOMING EXTRATROPICAL
  96HR VT     21/0600Z 49.0N  37.0W    45 KT...EXTRATROPICAL
 120HR VT     22/0600Z 56.0N  27.5W    45 KT...EXTRATROPICAL
  
 $$
 FORECASTER BROWN
  
 
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