225
WTPZ45 KNHC 082032
TCDEP5
TROPICAL STORM SIMON DISCUSSION NUMBER 6
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202026
300 PM CST THU OCT 08 2026
SIMON IS ALMOST A HURRICANE. THE STORM CONTINUES TO HAVE A VERY
COMPACT INNER CORE WITH SOME SIGNS OF AN EYE BECOMING APPARENT IN
SATELLITE IMAGES. THERE ARE ALSO NUMEROUS SPIRAL BANDS BEYOND THE
INNER CORE REGION, WITH THE OUTERMOST BAND IN THE FAR NORTHEAST
QUADRANT STILL AFFECTING PORTIONS OF SOUTHWESTERN MEXICO. THE LATEST
SATELLITE INTENSITY ESTIMATES HAVE INCREASED A LITTLE FROM EARLIER
AND NOW RANGE FROM ABOUT 50 TO 65 KT. BASED ON THAT DATA, THE
INITIAL INTENSITY IS NUDGED UP TO 60 KT. A 17Z ASCAT-C PASS WAS USED
TO ADJUST THE INITIAL WIND RADII.
THE TROPICAL STORM IS MOVING SLOWLY WESTWARD AT ABOUT 5 KT, STEERED
BY A WEAK MID-LEVEL RIDGE TO ITS NORTH. A TURN TO THE NORTHWEST IS
EXPECTED TONIGHT OR EARLY FRIDAY, FOLLOWED BY A NORTHWARD MOTION
LATER THAT DAY WHEN THE RIDGE WEAKENS AND SHIFTS EASTWARD, IN
RESPONSE TO AN APPROACHING MID- TO UPPER-LEVEL TROUGH. ALTHOUGH THE
MODELS GENERALLY AGREE ON THE LARGE-SCALE STEERING PATTERN
EVOLUTION, THERE ARE VERY IMPORTANT DIFFERENCES IN WHERE AND WHEN
THE SYSTEM MAKES THAT TURN. THERE HAS BEEN A NOTABLE SHIFT TO THE
EAST THIS CYCLE, AND GIVEN THE WESTWARD BIAS OFTEN SEEN IN THE
MODELS FOR THIS REGION, THE NHC TRACK FORECAST HAS BEEN AGAIN NUDGED
EASTWARD. IT SHOULD BE NOTED THAT THE BEST-PERFORMING MODELS OF THE
YEAR SO FAR ARE EAST OF THE OFFICIAL FORECAST, AND ADDITIONAL
ADJUSTMENTS MIGHT BE NEEDED IF THIS TREND CONTINUES. THIS FORECAST
BRINGS THE CORE OF THE SYSTEM INLAND OVER SOUTHWESTERN AND
WEST-CENTRAL MEXICO SATURDAY AFTERNOON OR SATURDAY NIGHT.
SIMON IS IN NEAR IDEAL ENVIRONMENTAL CONDITIONS OF LOW WIND SHEAR,
HIGH MOISTURE, AND OVER VERY WARM WATERS. THE SHIPS MODEL SHOWS MORE
THAN A 70 PERCENT CHANCE THAT THE SYSTEM WILL RAPIDLY INTENSIFY OVER
THE NEXT 24 HOURS. IN FACT, THE STORM'S COMPACT INNER CORE STRUCTURE
MAKES IT EVEN MORE LIKELY THAT IT WILL CAPITALIZE ON THE FAVORABLE
CONDITIONS. THEREFORE, THE NHC INTENSITY FORECAST CONTINUES TO CALL
FOR RAPID STRENGTHENING INTO A VERY DANGEROUS CATEGORY 4 HURRICANE
BEFORE SIMON REACHES THE COAST OF WEST-CENTRAL MEXICO. THIS FORECAST
LIES NEAR THE HIGH END OF THE GUIDANCE, IN BEST AGREEMENT WITH THE
HCCA MODEL.
BASED ON THE NEW FORECAST, THE GOVERNMENT OF MEXICO HAS ISSUED A
HURRICANE WARNING FOR A PORTION OF THE COAST OF SOUTHWESTERN AND
WEST-CENTRAL MEXICO.
KEY MESSAGES:
1. SIMON IS EXPECTED TO STRENGTHEN TO A HURRICANE BY TONIGHT AND
APPROACH THE WEST-CENTRAL COAST OF MEXICO AS A MAJOR HURRICANE ON
SATURDAY.
2. LIFE-THREATENING WIND AND STORM SURGE IMPACTS ARE EXPECTED ALONG
A PORTION OF THE WEST-CENTRAL COAST OF MEXICO, AND A HURRICANE
WARNING IS NOW IN EFFECT FROM PUNTA SAN TELMO TO PLAYA PERULA.
PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE COMPLETED BY
LATE FRIDAY.
3. HEAVY RAINFALL ASSOCIATED WITH SIMON WILL IMPACT PORTIONS OF
SOUTHWESTERN MEXICO THROUGH THIS WEEKEND. THIS RAINFALL MAY PRODUCE
LIFE-THREATENING FLOODING AND MUDSLIDES, ESPECIALLY IN AREAS OF
STEEP TERRAIN.
4. SWELLS WILL AFFECT PORTIONS OF THE SOUTHWESTERN AND WEST-CENTRAL
COAST OF MEXICO THROUGH THE WEEKEND. THESE SWELLS ARE LIKELY TO
CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. PLEASE
CONSULT PRODUCTS FROM YOUR LOCAL WEATHER OFFICE.
FORECAST POSITIONS AND MAX WINDS
INIT 08/2100Z 15.7N 103.9W 60 KT 70 MPH
12H 09/0600Z 16.1N 104.4W 75 KT 85 MPH
24H 09/1800Z 16.8N 104.9W 95 KT 110 MPH
36H 10/0600Z 17.7N 105.0W 115 KT 130 MPH
48H 10/1800Z 18.8N 104.9W 115 KT 130 MPH
60H 11/0600Z 19.9N 104.9W 65 KT 75 MPH...INLAND
72H 11/1800Z 21.1N 104.8W 35 KT 40 MPH...INLAND
96H 12/1800Z 23.2N 105.0W 25 KT 30 MPH...POST-TROP/INLAND
120H 13/1800Z...DISSIPATED
FORECASTER CANGIALOSI
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