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 882 
 WTPZ41 KNHC 120852
 TCDEP1
  
 TROPICAL STORM IRWIN DISCUSSION NUMBER  25
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP112011
 200 AM PDT WED OCT 12 2011
  
 IRWIN HAS BECOME LESS ORGANIZED DURING THE PAST SEVERAL HOURS WITH
 ONLY A PUNY AREA OF CONVECTION NEAR THE CENTER. DVORAK
 CLASSIFICATIONS SUPPORT REDUCING THE WIND SPEED TO 35 KT FOR THIS
 ADVISORY. MODERATE-TO-STRONG EASTERLY SHEAR SHOULD AFFECT THE
 TROPICAL CYCLONE FOR THE NEXT COUPLE OF DAYS...AND IRWIN IS
 FORECAST TO MOVE INTO SOMEWHAT COOLER WATERS DUE TO THE WAKE OF
 HURRICANE JOVA. THESE FACTORS SHOULD CAUSE IRWIN TO WEAKEN INTO A
 TROPICAL DEPRESSION WITHIN 24 HOURS...AND THE NHC FORECAST REFLECTS
 THIS LIKELIHOOD. HOWEVER...THE INTENSITY FORECAST GETS RATHER
 DIFFICULT IN THE MEDIUM RANGE AS IRWIN SHOULD EVENTUALLY MOVE OVER
 RATHER WARM WATERS WITH SOME GLOBAL MODELS SHOWING A LESSENING OF
 THE EASTERLY SHEAR. WHILE SOME RESTRENGTHENING IS NOT OUT OF THE
 QUESTION...THERE PROBABLY WILL NOT BE MUCH LEFT OF IRWIN TO TAKE
 ADVANTAGE OF THE MORE FAVORABLE CONDITIONS AT THAT TIME. THUS THE
 NHC FORECAST WILL CONTINUE TO SHOW THE CYCLONE BECOMING A REMNANT
 LOW BY DAY 4.
  
 IRWIN APPEARS TO HAVE TURNED A LITTLE NORTH OF DUE EAST...AND THE
 INITIAL MOTION ESTIMATE IS 075/9. A MID-LEVEL LOW LOCATED A FEW
 HUNDRED MILES TO THE SOUTHWEST OF THE BAJA PENINSULA SHOULD STEER
 THE STORM ON A FASTER MOTION TOWARD THE EAST-NORTHEAST FOR A DAY OR
 SO. THEREAFTER...THE CYCLONE IS EXPECTED TO BE DRAWN TO THE EAST
 AND EAST-SOUTHEAST AS IT BECOMES MORE ENTANGLED WITH THE EASTERN
 PACIFIC MONSOON TROUGH...AND EVENTUALLY BEGINS TO MOVE WESTWARD IN
 THE LONGER RANGE DUE TO A REBUILDING RIDGE OVER MEXICO. FOR SUCH A
 COMPLICATED STEERING PATTERN...THE MODELS ARE IN FAIR AGREEMENT...
 AND THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS ONE...BETWEEN THE
 ECMWF MODEL AND THE MULTI-MODEL CONSENSUS EXCLUDING THE HWRF MODEL.  
  
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  12/0900Z 15.2N 112.3W   35 KT  40 MPH
  12H  12/1800Z 16.0N 110.7W   35 KT  40 MPH
  24H  13/0600Z 17.2N 108.4W   30 KT  35 MPH
  36H  13/1800Z 17.3N 106.1W   30 KT  35 MPH
  48H  14/0600Z 16.8N 104.5W   30 KT  35 MPH
  72H  15/0600Z 16.0N 104.0W   30 KT  35 MPH
  96H  16/0600Z 15.5N 105.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
 120H  17/0600Z 15.5N 107.5W   30 KT  35 MPH...POST-TROP/REMNT LOW
  
 $$
 FORECASTER BLAKE
  
 
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