000
WTNT45 KNHC 012335
TCDAT5
 
TROPICAL STORM EMILY SPECIAL DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL052011
730 PM AST MON AUG 01 2011
 
DATA FROM THE AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
INVESTIGATING THE SYSTEM OVER THE LESSER ANTILLES SHOW THAT A
WELL-DEFINED CIRCULATION CENTER HAS FINALLY FORMED NEAR THE ISLAND
OF DOMINICA...MARKING THE FORMATION OF TROPICAL STORM EMILY.  THE
INITIAL INTENSITY OF 35 KT IS BASED ON FLIGHT LEVEL WINDS OF AROUND
45 KT IN DEEP CONVECTION NORTH OF THE CENTER.  AS EVIDENCED BY THE
AMOUNT OF TIME IT TOOK THIS SYSTEM TO CONSOLIDATE AROUND A SINGLE
CENTER...THE ENVIRONMENT IS ONLY MARGINALLY FAVORABLE FOR
STRENGTHENING IN THE SHORT TERM.  THE MAIN INHIBITING FACTOR
APPEARS TO BE MID-LEVEL RELATIVE HUMIDITY VALUES OF 50 PERCENT OR
LESS AS SEEN IN THE SHIPS MODEL OUTPUT.  THE OFFICIAL FORECAST
FOLLOWS THE SHIPS MODEL THROUGH 36 HOURS...AND THEN ASSUMES THAT
EMILY WILL WEAKEN AS IT ENCOUNTERS HISPANIOLA IN 48 HOURS OR SO. 
BEYOND THAT TIME...IF EMILY SURVIVES THE INTERACTION WITH THE
RUGGED TERRAIN ON THE ISLAND...GRADUAL STRENGTHENING IS SHOWN NEAR
THE END OF THE PERIOD...AND THE OFFICIAL FORECAST IS CLOSE TO THE
IVCN CONSENSUS BY DAY 5.  NEEDLESS TO SAY...THE INTENSITY FORECAST
IS OF VERY LOW CONFIDENCE GIVEN THE PRESENT ORGANIZATION OF THE
SYSTEM AND THE POTENTIAL LAND INTERACTION IN 2 OR 3 DAYS. 

THE LOW-LEVEL CIRCULATION HAS BEEN MOVING QUICKLY WESTWARD...AND THE
INITIAL MOTION ESTIMATE IS A HIGHLY UNCERTAIN 275/15. EMILY IS
CURRENTLY SITUATED TO THE SOUTH OF A WEAKENING MID-LEVEL RIDGE OVER
THE SUBTROPICAL WESTERN ATLANTIC. THE GLOBAL MODELS ARE IN
GENERALLY GOOD AGREEMENT SHOWING THIS RIDGE WEAKENING OVER THE NEXT
COUPLE OF DAYS AS A MID-LEVEL TROUGH DIGS SOUTHWARD OVER THE
WESTERN ATLANTIC. THIS SHOULD ALLOW EMILY TO TURN
WEST-NORTHWESTWARD AND SLOW DOWN A LITTLE IN THE FIRST 48 HOURS.
BEYOND THAT TIME...THE TRACK FORECAST IS HIGHLY UNCERTAIN AND
DEPENDS ON WHAT SHAPE EMILY IS IN AFTER IT MOVES PAST HISPANIOLA
AND HOW MUCH THE RIDGE RE-BUILDS TO THE NORTH OF THE CYCLONE OVER
THE WESTERN ATLANTIC TOWARD THE END OF THE PERIOD. THERE IS QUITE A
BIT OF SPREAD IN THE TRACK MODEL GUIDANCE...WITH THE ECMWF TAKING A
WEAKER CYCLONE FARTHEST TO THE WEST SHOWING A TRACK NEAR SOUTHERN
FLORIDA...WHILE THE GFDL AND THE NEW 18Z GFS ARE FARTHEST TO THE
RIGHT WITH A TRACK NEAR OR EAST OF THE BAHAMAS. THE OFFICIAL
FORECAST IS A LITTLE SOUTH OF THE GUIDANCE IN THE FIRST 12 TO 24
HOURS TO ACCOUNT FOR THE MORE WESTERLY INITIAL MOTION AND LIES
CLOSE TO THE TVCA MULTI-MODEL CONSENSUS BEYOND THAT TIME. GIVEN THE
SPREAD IN THE GUIDANCE LATE IN THE PERIOD...THIS IS A GOOD TIME TO
REMIND EVERYONE THAT THE AVERAGE ERROR OF THE OFFICIAL NHC TRACK
FORECAST IS ABOUT 250 MILES AT 5 DAYS. 

GIVEN THE FORECAST PARTICULARS...A VARIETY OF TROPICAL STORM WATCHES
AND WARNINGS HAVE BEEN ISSUED FOR PORTIONS OF THE LEEWARD
ISLANDS...THE U.S. VIRGIN ISLANDS...PUERTO RICO...AND HISPANIOLA.  

NOTE...THIS SPECIAL ADVISORY WILL TAKE THE PLACE OF THE STANDARD
0000 UTC INTERMEDIATE PUBLIC ADVISORY.  THE NEXT ADVISORY WILL THE
THE FULL ADVISORY ISSUED AT 0300 UTC/1100 PM AST/EDT.  
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  01/2330Z 15.2N  62.0W   35 KT  40 MPH
 12H  02/0600Z 15.6N  63.5W   40 KT  45 MPH
 24H  02/1800Z 16.5N  66.0W   45 KT  50 MPH
 36H  03/0600Z 17.4N  68.5W   50 KT  60 MPH
 48H  03/1800Z 18.4N  70.5W   50 KT  60 MPH...INLAND
 72H  04/1800Z 21.0N  74.0W   40 KT  45 MPH...OVER WATER
 96H  05/1800Z 24.0N  77.5W   50 KT  60 MPH
120H  06/1800Z 26.0N  79.5W   65 KT  75 MPH
 
$$
FORECASTER BRENNAN