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Tropical Storm RAYMOND Forecast Discussion Number 21
2013-10-25 04:33:49| National Hurricane Center (East Pacific)
Issued at 800 PM PDT THU OCT 24 2013 000 WTPZ42 KNHC 250233 TCDEP2 TROPICAL STORM RAYMOND DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL EP172013 800 PM PDT THU OCT 24 2013 RAYMOND HAS MADE A COMEBACK TONIGHT. A LARGE CLUSTER OF DEEP CONVECTION HAS FORMED NEAR THE CENTER...AND THE OVERALL CLOUD PATTERN HAS BECOME BETTER ORGANIZED. THE INITIAL INTENSITY HAS BEEN ADJUSTED UPWARD TO 50 KNOTS...BASED ON A BLEND OF SUBJECTIVE T-NUMBERS FROM TAFB AND SAB...AND OBJECTIVE NUMBERS FROM THE UNIVERSITY OF WISCONSIN. THE GLOBAL MODELS...PRIMARILY THE GFS AND THE ECMWF...HAVE DONE A REMARKABLY GOOD JOB IN FORECASTING THE CHANGE FROM UNFAVORABLE TO FAVORABLE UPPER-LEVEL WINDS. NOW THAT THIS FAVORABLE PATTERN HAS MATERIALIZED...AS SEEN BY A WESTWARD EXPANSION OF THE OUTFLOW...THE NHC FORECAST CALLS FOR RAYMOND TO REACH HURRICANE STRENGTH AGAIN IN A DAY OR SO OVER OPEN WATERS. THIS IS CONSISTENT WITH THE INTENSITY CONSENSUS AND WITH THE UPWARD INTENSITY TREND SHOWN BY GUIDANCE TONIGHT. THE HWRF APPEARS TO BE ALONE IN THIS FORECAST CYCLE...KEEPING RAYMOND ON A GRADUAL STEADY DECAY OR WITH NO CHANGE IN INTENSITY. BY THE END OF THE FORECAST PERIOD...WHEN THE SHEAR INCREASES WITH THE ARRIVAL OF A NEW MID- TO UPPER-LEVEL TROUGH...AND THE INFLUENCE OF COOLER WATERS...WEAKENING SHOULD THEN BEGIN. THE SUBTROPICAL RIDGE TO THE NORTH OF RAYMOND HAS CONTINUED TO EXPAND AND IS FORCING THE CYCLONE TO MOVE TOWARD THE WEST OR 265 DEGREES AT 9 KNOTS. THIS SUBTROPICAL RIDGE IS NOT GOING ANYWHERE DURING THE NEXT 3 DAYS OR SO...AND THIS STEERING PATTERN WILL KEEP RAYMOND ON A GENERAL WESTWARD TRACK AWAY FROM MEXICO. BY DAY 4 AND BEYOND...THE SAME APPROACHING TROUGH WHICH WILL INDUCE THE SHEAR WILL ALSO ERODE THE SUBTROPICAL RIDGE. THE CYCLONE SHOULD THEN SLOW DOWN AND TURN NORTHWARD AHEAD OF THE TROUGH. MOST OF THE GUIDANCE IS CONSISTENT WITH THE WESTWARD MOTION TROUGH DAY 3 OR SO...BUT AFTER THAT TIME...THE TRACK BECOMES HIGHLY UNCERTAIN WITH SOME MODELS KEEPING THE CYCLONE MEANDERING...AND OTHERS MOVING IT NORTHWARD A LITTLE FASTER. THE FIRST SOLUTION IS THE MOST LIKELY SCENARIO TO OCCUR SINCE BY THAT TIME...RAYMOND SHOULD BE WEAKER AND STEERED BY A MUCH LIGHTER LOW-LEVEL FLOW. FORECAST POSITIONS AND MAX WINDS INIT 25/0300Z 14.6N 107.7W 50 KT 60 MPH 12H 25/1200Z 14.5N 109.2W 55 KT 65 MPH 24H 26/0000Z 14.0N 111.5W 60 KT 70 MPH 36H 26/1200Z 13.7N 113.6W 65 KT 75 MPH 48H 27/0000Z 13.5N 116.0W 65 KT 75 MPH 72H 28/0000Z 14.0N 119.0W 65 KT 75 MPH 96H 29/0000Z 15.5N 120.0W 55 KT 65 MPH 120H 30/0000Z 17.0N 120.0W 45 KT 50 MPH $$ FORECASTER AVILA
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