695
WTPZ45 KNHC 142055
TCDEP5
HURRICANE SIMON DISCUSSION NUMBER 30
NWS NATIONAL HURRICANE CENTER MIAMI FL EP202026
200 PM MST WED OCT 14 2026
SIMON IS SHOWING HOW SMALL TROPICAL CYCLONES CAN UNDERGO RAPID
WEAKENING AS WELL AS RAPID INTENSIFICATION. A SYNTHETIC APERTURE
RADAR (SAR) OVERPASS NEAR 13Z SHOWED WINDS IN THE EYEWALL OF 65-75
KT, SUGGESTING THAT THE INTENSITY IN THE PREVIOUS ADVISORY WAS TOO
HIGH. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT HAS JUST
REPORTED THAT THE STORM IS NOW WEAKER, WITH NO HURRICANE-FORCE
WINDS PRESENT SO FAR AT 700 MB. THE CENTRAL PRESSURE IS NEAR 989 MB
BASED ON A DROPSONDE WITH A SURFACE PRESSURE OF 993 MB AND SURFACE
WINDS OF 41 KT. THE INITIAL INTENSITY IS REDUCED TO 65 KT BASED
MAINLY ON THE CENTRAL PRESSURE, AND IT IS LIKELY THAT THIS IS
GENEROUS. THE AIRCRAFT REPORTED A 16-NM WIDE EYE OPEN TO THE
SOUTHWEST AND A LARGER RADIUS OF MAXIMUM WIND THAN SHOWN BY THE
EARLIER SAR DATA.
THE HURRICANE CONTINUES DRIFTING SOUTHWEST OR 235/3 KT. FOR THE
NEXT DAY OR SO, SIMON SHOULD CONTINUE DRIFTING SOUTHWESTWARD OR
SOUTHWARD IN AN AREA OF LIGHT STEERING CURRENTS, WITH THE CENTER
REMAINING WELL OFFSHORE. AFTER THAT TIME, THERE REMAINS SOME
SPREAD IN THE TRACK GUIDANCE MODELS. WHILE ALL OF THE GLOBAL MODELS
AGREE THAT A MID- TO UPPER-LEVEL TROUGH SHOULD FORM WEST OF BAJA
CALIFORNIA NEAR AND AFTER 48 H, THERE REMAINS DISAGREEMENT ON HOW
THIS WILL AFFECT SIMON'S TRACK. THE HAFS MODELS KEEP THE CYCLONE
MOVING SOUTHWARD THROUGH 72 H, WHILE THE GFS MODEL DOES NOT SHOW
ANY NORTHWARD TURN UNTIL 48 H. THE REMAINDER OF THE GUIDANCE
FORECASTS A TURN TOWARD THE NORTHWEST OR NORTH-NORTHWEST AROUND 36
H, WITH THAT MOTION CONTINUING THROUGH THE END OF THE FORECAST
PERIOD. THE NEW TRACK FORECAST FOLLOWS THE LATTER SCENARIO IN
ANTICIPATION THAT THE CENTER WILL TRY TO FOLLOW CONVECTIVE BURSTS
DISPLACED TO THE NORTH BY SOUTHERLY SHEAR. OVERALL, THE TRACK
GUIDANCE ENVELOPE HAS SHIFTED WESTWARD SINCE THE PREVIOUS ADVISORY,
AND SO HAS THE TRACK FORECAST.
SIMON IS CURRENTLY EXPERIENCING LIGHT TO MODERATE NORTHERLY SHEAR
AND DRY AIR ENTRAINMENT, AND THIS COMBINATION HAS AT LEAST
TEMPORARILY DISRUPTED THE EYEWALL CONVECTION. THE SHEAR IS LIKELY
TO SUBSIDE DURING THE NEXT 6-18 H, AND BASED ON THIS THE INTENSITY
FORECAST KEEPS THE CYCLONE AS A MINIMAL HURRICANE. AFTER 36 H,
INCREASING SOUTHERLY AND SOUTHWESTERLY UPPER-LEVEL WINDS BETWEEN
THE TROUGH TO THE NORTHWEST AND TROPICAL STORM TRUDY TO THE
SOUTHEAST SHOULD CAUSE SIGNIFICANT SHEAR OVER SIMON. THE INTENSITY
FORECAST SHOWS STEADY WEAKENING DURING THIS TIME, AND THERE IS A
POSSIBILITY THAT SIMON COULD WEAKEN FASTER AND DISSIPATE SOONER THAN
CURRENTLY FORECAST.
KEY MESSAGES:
1. INTERESTS IN BAJA CALIFORNIA SUR SHOULD CONTINUE TO CLOSELY
MONITOR THE LATEST UPDATES. WATCHES OR WARNINGS COULD BE REQUIRED
FOR PORTIONS OF BAJA CALIFORNIA SUR OVER THE NEXT DAY OR TWO.
2. LARGE SWELLS WILL LIKELY AFFECT PORTIONS OF THE COAST OF
WEST-CENTRAL MEXICO AND BAJA CALIFORNIA SUR OVER THE NEXT SEVERAL
DAYS. THESE SWELLS COULD CAUSE LIFE-THREATENING SURF AND RIP CURRENT
CONDITIONS.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 19.3N 108.3W 65 KT 75 MPH
12H 15/0600Z 19.2N 108.5W 65 KT 75 MPH
24H 15/1800Z 19.1N 108.4W 65 KT 75 MPH
36H 16/0600Z 19.5N 108.6W 65 KT 75 MPH
48H 16/1800Z 20.3N 109.5W 60 KT 70 MPH
60H 17/0600Z 21.5N 110.5W 55 KT 65 MPH
72H 17/1800Z 22.8N 111.5W 45 KT 50 MPH
96H 18/1800Z 24.9N 113.2W 30 KT 35 MPH
120H 19/1800Z 26.7N 114.2W 25 KT 30 MPH...POST-TROP/REMNT LOW
FORECASTER BEVEN
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