000
WTNT45 KNHC 051445
TCDAT5
 
TROPICAL STORM ERNESTO DISCUSSION NUMBER  16
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052012
1100 AM EDT SUN AUG 05 2012
 
AN AIR FORCE HURRICANE HUNTER AIRCRAFT HAS BEEN INVESTIGATING
ERNESTO THIS MORNING AND FOUND THAT THE LOW-LEVEL CENTER IS LESS
WELL-DEFINED THAN IT WAS YESTERDAY.  ALSO...VISIBLE SATELLITE
IMAGERY SHOWS THAT THE CENTER IS DISPLACED TO THE WEST OF MOST OF
THE DEEP CONVECTION.  PRECIPITABLE WATER IMAGERY AND GLOBAL MODEL
ANALYSES INDICATE DRY LOW- TO MID-LEVEL AIR WEST AND SOUTH OF THE
TROPICAL CYCLONE...AND THIS HAS PROBABLY BEEN DISRUPTING THE
SYSTEM.  ASSUMING THAT ERNESTO IS ABLE TO OVERCOME THIS UNFAVORABLE
THERMODYNAMIC FACTOR...SOME STRENGTHENING IS POSSIBLE WHEN THE
FORWARD SPEED SLOWS IN A DAY OR SO.  THE OFFICIAL FORECAST IS CLOSE
TO THE INTENSITY MODEL CONSENSUS BUT CONTINUES TO BE BELOW THE
STATISTICAL-DYNAMICAL LGEM/SHIPS GUIDANCE.  THE LATTER HAS BEEN
SHOWING SOMEWHAT OF A HIGH BIAS FOR THIS SYSTEM.  THE GFS MODEL
CONTINUES TO SHOW NO STRENGTHENING.
 
THE STORM CONTINUES TO MOVE SWIFTLY TOWARD THE WEST...AT A FORWARD
SPEED OF AT LEAST 20 KT.  GLOBAL MODELS INDICATE THAT THE MID-LEVEL
RIDGE TO THE NORTH OF THE TROPICAL CYCLONE WILL WEAKEN IN A DAY OR
TWO...WHICH SHOULD CAUSE THE FORWARD MOTION TO DECELERATE.  MOST OF
THE TRACK GUIDANCE...AND THE OFFICIAL FORECAST...SHOWS A TURN
TOWARD THE WEST-NORTHWEST IN A DAY OR SO.  A MID-TROPOSPHERIC
TROUGH OVER THE EASTERN U.S. IS EXPECTED TO WEAKEN THE RIDGE A
LITTLE MORE OVER THE GULF OF MEXICO IN A FEW DAYS.  ALTHOUGH THE
GFDL AND U.K. MET MODEL FORECASTS SHOW A MOTION TOWARD THE
NORTHWEST GULF COAST IN THE LATTER PART OF THE FORECAST
PERIOD...THE TROUGH IS NOT EXPECTED TO WEAKEN THE RIDGE ENOUGH TO
CAUSE A SIGNIFICANT NORTHWARD TURN.  THIS IS CONFIRMED BY THE GFS
AND ECMWF RUNS...AND IN FACT THE LATEST GFS FORECAST BARELY BRINGS
THE TROPICAL CYCLONE INTO THE GULF.  THE OFFICIAL FORECAST IS A
LITTLE SOUTH OF THE PREVIOUS ONE...AND CLOSE TO THE ECMWF TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  05/1500Z 15.0N  77.1W   45 KT  50 MPH
 12H  06/0000Z 15.0N  79.4W   45 KT  50 MPH
 24H  06/1200Z 15.4N  81.8W   45 KT  50 MPH
 36H  07/0000Z 15.9N  83.6W   50 KT  60 MPH
 48H  07/1200Z 16.5N  85.3W   55 KT  65 MPH
 72H  08/1200Z 18.0N  89.0W   55 KT  65 MPH...INLAND
 96H  09/1200Z 20.0N  92.5W   50 KT  60 MPH
120H  10/1200Z 21.5N  96.0W   65 KT  75 MPH
 
$$
FORECASTER PASCH/ROBERTS