Tropical Storm EMILY

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TROPICAL STORM EMILY DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052011
1100 PM AST TUE AUG 02 2011
 
THE AREA OF COLD CLOUD TOPS HAS EXPANDED OVER THE PAST FEW HOURS IN
A CDO-LIKE PATTERN...HOWEVER A 2157 UTC SSMIS PASS SUGGESTED THAT
THE LOW-LEVEL CENTER REMAINS DISPLACED TO THE WEST OF THE DEEPEST
CONVECTION.  DVORAK CURRENT INTENSITY ESTIMATES WERE 3.0...45
KT...FROM TAFB AND SAB AT 00Z...THAT THAT WILL REMAIN THE INTENSITY
FOR THIS ADVISORY PACKAGE.  ANOTHER AIR FORCE RESERVE HURRICANE
HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE EMILY OVERNIGHT.
UW-CIMSS SATELLITE ANALYSIS SHOWS ABOUT 12 KT OF WESTERLY SHEAR
OVER EMILY...WHICH IS CONSISTENT WITH THE TILTED STRUCTURE OF THE
CYCLONE AND THE LOCATION OF A MID-LEVEL CIRCULATION SEEN IN VELOCITY
DATA FROM THE SAN JUAN DOPPLER RADAR.  OVERALL THE ENVIRONMENT
APPEARS FAVORABLE FOR SOME CONTINUED STRENGTHENING UNTIL THE
CYCLONE REACHES HISPANIOLA IN ABOUT 24 HOURS...AND THE OFFICIAL
FORECAST HAS BEEN ADJUSTED UPWARD A BIT IN AGREEMENT WITH THE IVCN
INTENSITY CONSENSUS THROUGH THAT TIME.  IF EMILY SURVIVES ITS TRIP
ACROSS THE HIGH TERRAIN OF HISPANIOLA...THE ENVIRONMENT APPEARS
SUPPORTIVE OF RE-INTENSIFICATION LATE IN THE PERIOD.  THE OFFICIAL
FORECAST HAS BEEN ADJUSTED UPWARD A LITTLE FROM THE PREVIOUS
ADVISORY...BUT REMAINS BELOW THE GUIDANCE GIVEN THE UNCERTAINTY IN
HOW EMILY WILL FARE AFTER LAND INTERACTION.
 
THE CENTER HAS BEEN DIFFICULT TO LOCATE THIS EVENING GIVEN THE LACK
OF AIRCRAFT AND MICROWAVE DATA.  BASED ON THE ABOVE-MENTIONED SSMIS
PASS...THE CENTER IS ASSUMED TO BE WEST OF THE COLDEST CLOUD TOPS...
YIELDING AN UNCERTAIN INITIAL MOTION ESTIMATE OF 285/12...TOWARD THE
WEST-NORTHWEST.  THE SYNOPTIC REASONING REMAINS UNCHANGED...AS A
MID-LEVEL TROUGH WILL REACH MAXIMUM AMPLITUDE OVER THE WESTERN
ATLANTIC IN THE NEXT 24 HOURS...ALLOWING EMILY TO TURN
NORTHWESTWARD AND MOVE ACROSS HISPANIOLA AND INTO THE SOUTHEASTERN
BAHAMAS IN THE NEXT 24 TO 36 HOURS.  AFTER THE TROUGH LIFTS OUT A
MID-LEVEL WEAKNESS IS EXPECTED TO PERSIST OVER THE SOUTHWESTERN
ATLANTIC THROUGH THE END OF THE FORECAST PERIOD...AND EMILY SHOULD
TURN NORTHWARD INTO THE WEAKNESS AND EVENTUALLY ACCELERATE
NORTH-NORTHEASTWARD BY DAY 5 AS A RIDGE REBUILDS TO THE SOUTHEAST
OF THE CYCLONE AND A BROAD TROUGH MOVES INTO THE EASTERN UNITED
STATES.  THE BIGGEST CHANGE IN THE GUIDANCE FOR THIS CYCLE IS THAT
THE GFDL AND HWRF NOW SHOW A LITTLE MORE RIDGING EAST OF EMILY LATE
IN THE PERIOD AND HAVE SHIFTED THEIR TRACKS WESTWARD...ESPECIALLY
AT DAYS 3 AND 4.  THROUGH THE FIRST 36 HOURS...THE NEW NHC FORECAST
IS ALONG THE OLD TRACK...BUT A LITTLE FASTER AS IT TRENDS TOWARD
THE FASTER MULTI-MODEL CONSENSUS.  FROM 48 TO 96 HOURS...THE NEW
NHC FORECAST HAS BEEN ADJUSTED A LITTLE TO THE LEFT OF THE PREVIOUS
PACKAGE...AND NOW LIES TO THE RIGHT OF THE MULTI-MODEL CONSENSUS. 
GIVEN THE LARGE CYCLE-TO-CYCLE VARIABILITY SEEN IN THE TRACK
GUIDANCE...UNCERTAINTY IN THE TRACK FORECAST REMAINS LARGER THAN
USUAL BEYOND 48 HOURS.
 
BASED ON THE INCREASE IN FORWARD SPEED WITH THE NEW TRACK FORECAST
...A TROPICAL STORM WARNING HAS BEEN ISSUED FOR THE SOUTHEAST
BAHAMAS AND TURKS AND CAICOS.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  03/0300Z 16.2N  66.7W   45 KT  50 MPH
 12H  03/1200Z 17.0N  68.4W   50 KT  60 MPH
 24H  04/0000Z 18.4N  70.5W   55 KT  65 MPH...INLAND
 36H  04/1200Z 20.2N  72.6W   35 KT  40 MPH...OVER WATER
 48H  05/0000Z 22.0N  74.4W   35 KT  40 MPH
 72H  06/0000Z 26.0N  77.5W   45 KT  50 MPH
 96H  07/0000Z 29.5N  78.5W   55 KT  65 MPH
120H  08/0000Z 33.0N  76.0W   65 KT  75 MPH
 
$$
FORECASTER BRENNAN
 
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