607
WTPZ45 KNHC 151443
TCDEP5
TROPICAL STORM SIMON DISCUSSION NUMBER 33
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202026
800 AM MST THU OCT 15 2026
FIRST LIGHT VISIBLE IMAGERY, ALONG WITH GPM AND AMSR-3 MICROWAVE
DATA, SHOW THAT THE CONVECTIVE ORGANIZATION OF SIMON HAS CHANGED A
BIT, WITH THE MAIN CONVECTION NOW IN A BAND TO THE WEST OF THE
CENTER. THE VARIOUS SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY
ESTIMATES ARE IN THE 40-55 KT RANGE AND HAVE NOT CHANGED MUCH
DURING THE PAST 6 H. BASED ON THIS, THE INITIAL INTENSITY REMAINS A
POSSIBLY GENEROUS 50 KT.
THE MICROWAVE OVERPASSES SUGGEST THE CENTER OF SIMON IS A LITTLE TO
THE EAST OF THE PREVIOUS ADVISORY POSITION, AND IT APPEARS THAT THE
CYCLONE MAY BE MAKING A SMALL LOOP IN ITS TRACK. LITTLE MOTION IS
EXPECTED FOR THE NEXT 12 H OR SO AS SIMON REMAINS EMBEDDED IN AN
AREA OF WEAK STEERING CURRENTS. AFTER THAT TIME, A MID- TO
UPPER-LEVEL LOW IS FORECAST TO FORM NEAR OR WEST OF THE NORTHERN
BAJA CALIFORNIA PENINSULA WHILE A WEAK MID-LEVEL RIDGE DEVELOPS OVER
NORTHERN AND CENTRAL MEXICO. THIS SHOULD CAUSE SIMON TO MOVE
NORTHWESTWARD NEAR, BUT WEST OF, THE COAST OF BAJA CALIFORNIA SUR,
AND THIS MOTION IS EXPECTED TO CONTINUE UNTIL THE SYSTEM
DISSIPATES. THE CURRENT TRACK GUIDANCE IS IN BETTER AGREEMENT IN
BOTH DIRECTION AND SPEED THAT IT WAS 24 H AGO, AND THE NEW FORECAST
TRACK LIES NEAR THE CENTER OF THE GUIDANCE ENVELOPE. THE NEW
FORECAST IS A LITTLE TO THE EAST OF THE PREVIOUS FORECAST THROUGH
60 H BASED MAINLY ON THE INITIAL POSITION, AND AFTER THAT IT IS
CLOSE TO THE PREVIOUS FORECAST. GIVEN THE NEW TRACK FORECAST AND
THE SMALL SIZE OF SIMON, WIND WATCHES ARE NOT NEEDED FOR BAJA
CALIFORNIA SUR AT THIS TIME.
THE SHEAR OVER SIMON HAS DECREASED SINCE YESTERDAY, AND IT SHOULD
REMAIN LIGHT FOR THE NEXT 12-18 H. HOWEVER, THE STORM IS EMBEDDED
IS A DRY AIR MASS, SO IT LIKELY WILL NOT BE ABLE TO TAKE ADVANTAGE
OF THE DECREASED SHEAR. AFTER 18 H, SOUTHERLY AND SOUTHWESTERLY
UPPER-LEVEL WINDS ARE FORECAST TO INCREASE BETWEEN THE TROUGH TO THE
NORTHWEST OF SIMON AND HURRICANE TRUDY TO THE SOUTHEAST. THIS WILL
RESULT IN STRONG SHEAR OVER SIMON THAT SHOULD CAUSE THE CYCLONE TO
WEAKEN. THE INTENSITY FORECAST SHOWS THE SYSTEM BECOMING A REMNANT
LOW PRESSURE AREA BY 72 H AND DISSIPATING COMPLETELY BY 120 H, AND
GLOBAL MODEL GUIDANCE SUGGESTS THESE EVENTS COULD HAPPEN EARLIER
THAN CURRENTLY FORECAST.
KEY MESSAGES:
1. INTERESTS IN BAJA CALIFORNIA SUR SHOULD CONTINUE TO CLOSELY
MONITOR THE LATEST UPDATES AS SIMON IS EXPECTED TO PASS NEAR OR WEST
OF THAT AREA THIS WEEKEND.
2. LARGE SWELLS WILL LIKELY AFFECT PORTIONS OF THE COAST OF
WEST-CENTRAL MEXICO AND BAJA CALIFORNIA SUR OVER THE NEXT COUPLE OF
DAYS. THESE SWELLS COULD CAUSE LIFE-THREATENING SURF AND RIP CURRENT
CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 15/1500Z 19.2N 108.1W 50 KT 60 MPH
12H 16/0000Z 19.5N 108.1W 45 KT 50 MPH
24H 16/1200Z 20.2N 108.8W 45 KT 50 MPH
36H 17/0000Z 21.1N 110.0W 40 KT 45 MPH
48H 17/1200Z 21.9N 111.3W 35 KT 40 MPH
60H 18/0000Z 22.9N 112.6W 30 KT 35 MPH
72H 18/1200Z 24.0N 113.6W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 19/1200Z 26.8N 114.4W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 20/1200Z...DISSIPATED
FORECASTER BEVEN
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