857 
 WTNT41 KNHC 271440
 TCDAT1
 TROPICAL DEPRESSION ALEX DISCUSSION NUMBER   8
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL012010
 1000 AM CDT SUN JUN 27 2010
  
 RECENT SATELLITE IMAGERY INDICATES THAT THE CONVECTIVE TOPS NEAR THE
 CENTER OF ALEX HAVE WARMED AND DECREASED IN COVERAGE OVER THE PAST
 FEW HOURS.  BASED ON THESE TRENDS...AND A LACK OF ANY OBSERVATIONS
 OF STRONGER WINDS...THE INITIAL INTENSITY IS LOWERED TO 30 KT FOR
 THIS ADVISORY.
  
 THE INTENSITY FORECAST REASONING REMAINS UNCHANGED.  AFTER ALEX
 EMERGES INTO THE GULF...WARM WATERS AND LOW SHEAR WILL OFFER THE
 OPPORTUNITY FOR RESTRENGTHENING. GIVEN THAT THE LOW-LEVEL
 CIRCULATION OF ALEX REMAINS WELL DEFINED...THE FORECAST CALLS FOR
 ALEX TO REGAIN TROPICAL STORM STATUS BY TONIGHT...AND FOR STEADY
 INTENSIFICATION THROUGH 72 HOURS.  THE OFFICIAL FORECAST IS ABOVE
 ALL OF THE INTENSITY GUIDANCE THROUGH 48 HOURS...AND IS IN GOOD
 AGREEMENT WITH THE DECAY SHIPS MODEL BEYOND THAT TIME. NEEDLESS TO
 SAY...THE AMOUNT OF TIME THAT ALEX SPENDS OVER THE GULF WATERS WILL
 BE THE PIVOTAL FACTOR IN HOW MUCH INTENSIFICATION OCCURS.
  
 WHILE THE SHORT-TERM MOTION OF ALEX APPEARS ALMOST DUE WEST...A
 LONGER-TERM INITIAL MOTION ESTIMATE IS TOWARD THE WEST-NORTHWEST...
 295 DEGREES AT 10 KNOTS....A LITTLE TO THE LEFT OF THE PREVIOUS
 FORECAST TRACK. DURING THE FORECAST PERIOD...THE GLOBAL MODELS ARE
 IN GENERAL AGREEMENT WITH THE EVOLUTION OF THE LARGE-SCALE FLOW
 OVER NORTH AMERICA...WITH A LONGWAVE TROUGH DEVELOPING OVER THE
 EASTERN UNITED STATES IN TWO TO THREE DAYS...AND A MID- TO
 UPPER-LEVEL RIDGE DEVELOPING UPSTREAM OF THE TROUGH OVER CENTRAL
 NORTH AMERICA. HOWEVER...SUBTLE DIFFERENCES BETWEEN THE MODELS
 RESULT IN LARGE DIFFERENCES IN THE ULTIMATE TRACK OF ALEX. THE
 GFS...CANADIAN AND GFS ENSEMBLE MEAN ARE WEAKER WITH THE CENTRAL
 U.S. RIDGE IN 4 OR 5 DAYS. AS A RESULT...THESE MODELS HAVE BEEN
 PERSISTENTLY TAKING ALEX MORE POLEWARD. THE REMAINING MODELS
 SUGGEST THAT A STRONGER RIDGE NORTH OF ALEX WILL RESULT IN A MORE
 WESTWARD TURN LATE IN THE FORECAST PERIOD. THE ECMWF ENSEMBLE MEAN
 AND THE HWRF ARE ON THE NORTH SIDE OF THIS GROUP OF MODELS...BUT DO
 NOT SHOW A SHARP NORTHWARD TURN. ALL THAT BEING SAID...THE NEW
 OFFICIAL FORECAST IS ADJUSTED A LITTLE TO THE LEFT OF THE PREVIOUS
 ONE THROUGH 36 HOURS DUE TO THE INITIAL MOTION...AND BEYOND THAT
 TIME IS A LITTLE TO THE RIGHT OF THE PREVIOUS PACKAGE AND CLOSE TO
 THE TVCN MULTI-MODEL CONSENSUS.
  
 ALL OF THE MODEL UNCERTAINTY WITH THE TRACK OF ALEX OFFERS A
 REMINDER TO NOT TO FOCUS ON THE EXACT FORECAST TRACK...PARTICULARLY
 IN THE EXTENDED PART OF THE FORECAST PERIOD...WHERE AVERAGE
 FORECAST ERRORS CAN BE 200 TO 300 MILES.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      27/1500Z 18.7N  90.6W    30 KT
  12HR VT     28/0000Z 19.6N  91.6W    35 KT...OVER WATER
  24HR VT     28/1200Z 20.4N  92.6W    45 KT
  36HR VT     29/0000Z 21.1N  93.4W    55 KT
  48HR VT     29/1200Z 21.8N  94.2W    65 KT
  72HR VT     30/1200Z 23.0N  96.0W    75 KT
  96HR VT     01/1200Z 23.5N  98.0W    65 KT...INLAND
 120HR VT     02/1200Z 24.0N 100.5W    30 KT...INLAND
  
 $$
 FORECASTER BRENNAN