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Tropical Storm IGOR (Text)

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TROPICAL STORM IGOR DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL112010
500 PM AST WED SEP 08 2010
 
MODERATE TO STRONG CONVECTION CONTINUES TO BE LOCATED TO THE WEST OF
THE CENTER...A SYMPTOM OF EASTERLY SHEAR.  HIGH-RESOLUTION ASCAT
DATA EARLIER INDICATED PEAK WINDS OF 35-40 KT...AND WITH SATELLITE
CLASSIFICATIONS INCREASING...THE WIND SPEED IS RAISED TO 40 KT.  
 
AN UNCERTAIN ESTIMATE OF THE INITIAL MOTION IS 275/5.  THE
MOTION HAS SLOWED SIGNIFICANTLY...POSSIBLY DUE TO THE LOW PRESSURE
AREA APPROACHING THE NORTHERN CAPE VERDE ISLANDS.  THE GLOBAL
MODELS ARE SHOWING A DIFFERENT SCENARIO IN THE SHORT-TERM AND HAVE
TRENDED TOWARD THE 00/12Z ECMWF SOLUTIONS.  AS THE SMALL LOW TO
THE NORTHEAST OF IGOR MOVES WESTWARD...THE RIDGE IS FORECAST TO
WEAKEN SLIGHTLY...WHICH ALLOWS IGOR TO MOVE TO THE WEST-NORTHWEST
OR EVEN NORTHWEST BRIEFLY.  AFTERWARDS...THE RIDGE RESTRENGTHENS...
WHICH SHOULD TURN IGOR WESTWARD AGAIN.   THE NHC FORECAST IS
SHIFTED TO THE NORTH TO ACCOUNT FOR THE INTERACTION OF THE TWO
SYSTEMS AND THE NORTHWARD SHIFT IN THE MODELS...BUT STILL LIES
ALONG THE SOUTHERN EDGE OF THE ENVELOPE. 
 
THE INTENSITY FORECAST...AT LEAST IN THE SHORT-TERM...SEEMS TRICKY
WITH IGOR ONLY ABOUT 210 NM SOUTHWEST OF THE AFOREMENTIONED LOW. 
THERE CERTAINLY IS THE POTENTIAL FOR SOME SORT OF INTERACTION THAT
COULD SLOW THE STRENGTHENING PROCESS. THUS THE INTENSITY FORECAST
WILL ONLY SHOW SLOW INTENSIFICATION IN THE SHORT-TERM...GENERALLY A
LITTLE LOWER THAN THE MODELS.  IN THE LONGER-RANGE...THERE IS
PLENTY OF WARM WATER AND LIGHT SHEAR FORECAST IN THE PATH OF
IGOR...WHICH WOULD PROMOTE THE DEVELOPMENT OF A LARGE AND POWERFUL
HURRICANE.  THE NHC FORECAST IS INCREASED FROM THE PREVIOUS
ONE...CLOSE TO THE CONSENSUS...AND STILL MIGHT BE CONSERVATIVE AT
THE END.  HOWEVER...WITH THE TRACK FORECAST SHIFTING NORTHWARD... I
AM HESITANT TO FORECAST A MUCH STRONGER HURRICANE AT THIS TIME.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 13.9N  23.9W    40 KT
 12HR VT     09/0600Z 14.0N  24.8W    45 KT
 24HR VT     09/1800Z 14.7N  26.5W    50 KT
 36HR VT     10/0600Z 15.5N  29.1W    55 KT
 48HR VT     10/1800Z 16.3N  32.2W    60 KT
 72HR VT     11/1800Z 17.0N  37.5W    70 KT
 96HR VT     12/1800Z 17.5N  42.5W    80 KT
120HR VT     13/1800Z 18.5N  47.5W    90 KT
 
$$
FORECASTER BLAKE/PASCH
 
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