006
WTPZ45 KNHC 091447
TCDEP5
HURRICANE SIMON DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202026
900 AM CST FRI OCT 09 2026
THE INTENSITY OF SIMON HAS BEEN HARD TO DIAGNOSE THIS MORNING. THE
MOST RECENT TAFB DVORAK FIX STILL SUPPORTED AN INTENSITY OF 80 KT
AT 1200 UTC, WHILE ALL OF THE OBJECTIVE TECHNIQUES FROM UW-CIMSS
ARE LOWER. SINCE THAT TIME, A WARM SPOT NEAR THE CENTER OF SIMON'S
SMALL CDO HAS RECENTLY APPEARED, WHICH APPEARS TO BE THE EARLY
DEVELOPMENT OF AN EYE. BASED ON THE CONTINUED IMPROVEMENT IN SIMON'S
SATELLITE APPEARANCE, THE INITIAL INTENSITY HAS BEEN INCREASED TO 85
KT FOR THE ADVISORY.
OVER THE NEXT 24 HOURS, CONTINUED RAPID INTENSIFICATION IS EXPECTED.
THE RI PROBABILISTIC GUIDANCE (BOTH SHIPS AND DTOPS) ACTUALLY
DECREASED THIS CYCLE, BUT THE HURRICANE IS LOCATED IN A LOW-SHEAR,
HIGH-MOISTURE, AND HIGH-SST ENVIRONMENT THAT IS CONDUCIVE FOR
EXPLOSIVE DEEPENING. FURTHERMORE, RECENT MICROWAVE IMAGERY, SUCH AS
AN AMSR3 PASS JUST AFTER 08Z SUGGESTS THE HURRICANE HAS A SMALL
INNER-CORE, WHICH MAKES RAPID CHANGES IN INTENSITY MORE LIKELY.
THEREFORE, THE NHC FORECAST IS IN LINE WITH THE PREVIOUS ONE, ABOVE
MOST OF THE GUIDANCE AND SHOWS SIMON BECOMING A MAJOR HURRICANE
LATER TODAY.
SIMON'S FORECAST BEYOND THAT IS EXTREMELY DIFFICULT, AND THIS IS A
CASE WHERE IT IS IMPORTANT TO NOT FOCUS ON THE DETAILS OF NHC'S
DETERMINISTIC FORECAST. SIMON WILL TURN NORTHWARD THIS WEEKEND,
STEERED BETWEEN A DEEP TROUGH TO ITS NORTHWEST AND A RIDGE TO THE
EAST. THIS TRACK WILL TAKE THE CENTER OF SIMON VERY NEAR OR OVER THE
MEXICAN STATES OF COLIMA AND JALISCO. IF THE CENTER OF SIMON MOVES
OVER LAND, IT WILL QUICKLY WEAKEN AND COULD EVEN DISSIPATE,
DRASTICALLY LESSENING THE RISK OF HURRICANE-FORCE-WINDS FARTHER
NORTH IN MEXICO. HOWEVER, IF THE CORE OF SIMON REMAINS OFFSHORE, IT
WILL LIKELY CONTINUE NORTHWARD AS A HURRICANE. A MAJORITY OF THE
GUIDANCE THIS MORNING SHOWS SIMON REMAINING JUST OFFSHORE, HOWEVER
MOST OF THESE MODELS HAVE HISTORICALLY HAD A WEST BIAS IN THIS
REGION. LIKEWISE, ENSEMBLE MEANS LIKE GDM OR EVEN HCCA CAN BE
MISLEADING WHEN SOME MEMBERS MOVE INLAND AND DISSIPATE. THIS
RESULTS IN THE MEAN BEING COMPUTED SOLELY FROM THE SURVIVING, AND
IN THIS CASE FARTHER WEST, MEMBERS. THE NHC FORECAST THEREFORE
REMAINS WITHIN, BUT ON THE EAST SIDE OF THE GUIDANCE ENVELOPE, AND
IS BEST CHARACTERIZED AS A HEDGE BETWEEN THE AFOREMENTIONED
POSSIBILITIES.
KEY MESSAGES:
1. SIMON IS EXPECTED TO APPROACH THE WEST-CENTRAL COAST OF MEXICO
AS A MAJOR HURRICANE ON SATURDAY.
2. CATASTROPHIC WIND AND LIFE-THREATENING STORM SURGE IMPACTS ARE
LIKELY ALONG A PORTION OF THE WEST-CENTRAL COAST OF MEXICO, AND A
HURRICANE WARNING IS IN EFFECT FROM PUNTA SAN TELMO TO PUNTA MITA.
PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE COMPLETED BY
LATE TODAY.
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 09/1500Z 16.0N 104.7W 85 KT 100 MPH
12H 10/0000Z 16.5N 104.8W 105 KT 120 MPH
24H 10/1200Z 17.2N 104.9W 125 KT 145 MPH
36H 11/0000Z 18.2N 105.0W 125 KT 145 MPH
48H 11/1200Z 19.4N 105.2W 115 KT 130 MPH
60H 12/0000Z 20.7N 105.4W 95 KT 110 MPH...INLAND
72H 12/1200Z 21.9N 105.6W 75 KT 85 MPH...OVER WATER
96H 13/1200Z 23.6N 106.2W 55 KT 65 MPH...INLAND
120H 14/1200Z 24.9N 106.9W 30 KT 35 MPH...POST-TROP/INLAND
FORECASTER D. ZELINSKY
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