163
WTPZ42 KNHC 192053
TCDEP2
HURRICANE NORMA DISCUSSION NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172023
300 PM MDT THU OCT 19 2023
THE SATELLITE PRESENTATION OF NORMA HAS DETERIORATED SINCE THE LAST
ADVISORY. THE EYE HAS BECOME LESS DEFINED, AND THE INNER CORE
CONVECTION HAS BECOME MORE ASYMMETRIC. THE AIR FORCE RESERVE
HURRICANE HUNTERS THAT INVESTIGATED NORMA REPORTED THAT THE EYEWALL
WAS OPEN TO THE SOUTHEAST DURING THEIR FINAL PASS THROUGH THE
CENTER. STILL, THE AIRCRAFT DATA CONFIRM THAT NORMA IS A MAJOR
HURRICANE. THE HURRICANE HUNTERS REPORTED PEAK 700-MB FLIGHT-LEVEL
WINDS OF 111 KT, WITH SFMR RETRIEVALS AS HIGH AS 102 KT. THE MINIMUM
PRESSURE FROM A RECENT CENTER DROPSONDE WAS 945 MB WITH 12-KT WINDS.
THE INITIAL INTENSITY IS LOWERED TO 110 KT FOR THIS ADVISORY, WHICH
COULD BE A BIT GENEROUS BASED ON THE RECENT AIRCRAFT DATA.
BASED ON RECENT SATELLITE TRENDS, IT IS LIKELY THAT NORMA HAS
REACHED ITS PEAK INTENSITY. AN INCREASE IN SOUTHERLY SHEAR WILL
LIKELY CAUSE NORMA TO BECOME MORE VERTICALLY TILTED DURING THE NEXT
COUPLE OF DAYS, WHILE THE HURRICANE MOVES INTO A DRIER AND MORE
STABLE ENVIRONMENT AS DIAGNOSED FROM THE SHIPS GUIDANCE. THEREFORE,
WEAKENING IS FORECAST BEGINNING TONIGHT AND CONTINUING THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. STILL, NORMA IS FORECAST TO BE A
HURRICANE WHEN IT MOVES NEAR OR OVER THE SOUTHERN TIP OF THE BAJA
CALIFORNIA PENINSULA, AND THE GOVERNMENT OF MEXICO HAS ISSUED A
HURRICANE WARNING FOR THIS AREA BASED ON THE INCREASED RISK OF
HURRICANE CONDITIONS.
THE EYE OF NORMA HAS WOBBLED SOME TODAY, BUT THE LONG-TERM MOTION
REMAINS NORTHWARD (350/5 KT). A TURN TOWARD THE NORTH-NORTHWEST IS
EXPECTED DURING THE NEXT COUPLE OF DAYS WHILE NORMA APPROACHES THE
SOUTHERN TIP OF THE BAJA CALIFORNIA PENINSULA. THERE ARE STILL SPEED
DIFFERENCES IN THE VARIOUS GLOBAL AND REGIONAL MODELS, LIKELY
RELATED TO DIFFERENCES IN THE STEERING FLOW BASED ON THE VERTICAL
DEPTH OF THE CYCLONE. THE GFS AND REGIONAL MODELS SUGGEST NORMA WILL
REMAIN A DEEPER CYCLONE AND MOVE TOWARD THE WEST COAST OF MAINLAND
MEXICO IN 48-72 H. THE 12Z ECMWF, CANADIAN, AND UKMET RUNS SHOW
NORMA MAKING IT FARTHER NORTH THAN PREVIOUS RUNS, BUT STILL STALLING
NEAR THE SOUTHERN TIP OF BAJA BEFORE MOVING INLAND OVER WESTERN
MEXICO EARLY NEXT WEEK. THE UPDATED NHC TRACK FORECAST HAS BEEN
NUDGED WESTWARD AND IS FASTER THIS CYCLE, WHICH GENERALLY KEEPS IT
BETWEEN THE HCCA AND TVCE AIDS. THIS UPDATE SHOWS NORMA INLAND BY 96
H AND DISSIPATED OVER WESTERN MEXICO BY DAY 5, BUT THIS COULD OCCUR
SOONER THAN FORECAST IF THE GFS AND REGIONAL HURRICANE MODELS ARE
CORRECT. INTERESTS IN WESTERN MEXICO SHOULD MONITOR THE LATEST
FORECAST UPDATES, AS FUTURE TRACK AND/OR SPEED ADJUSTMENTS COULD BE
REQUIRED.
KEY MESSAGES:
1. A HURRICANE WARNING IS IN EFFECT FOR THE FAR SOUTHERN PORTION OF
THE BAJA CALIFORNIA PENINSULA, WHERE NORMA IS EXPECTED TO BRING
HURRICANE CONDITIONS ON SATURDAY WHEN IT PASSES NEAR OR OVER THE
AREA.
2. HEAVY RAINS FROM NORMA WILL BEGIN TO IMPACT THE FAR SOUTHERN
PORTIONS OF CALIFORNIA BAJA SUR ON LATE FRIDAY, CONTINUING THROUGH
SUNDAY. THIS RAINFALL MAY PRODUCE FLASH AND URBAN FLOODING, ALONG
WITH POSSIBLE MUDSLIDES IN AREAS OF HIGHER TERRAIN.
FORECAST POSITIONS AND MAX WINDS
INIT 19/2100Z 17.5N 108.0W 110 KT 125 MPH
12H 20/0600Z 18.5N 108.5W 105 KT 120 MPH
24H 20/1800Z 19.8N 109.1W 95 KT 110 MPH
36H 21/0600Z 21.2N 109.6W 80 KT 90 MPH
48H 21/1800Z 22.5N 109.7W 70 KT 80 MPH
60H 22/0600Z 23.6N 109.4W 60 KT 70 MPH
72H 22/1800Z 24.2N 108.9W 50 KT 60 MPH
96H 23/1800Z 25.0N 107.5W 30 KT 35 MPH...INLAND
120H 24/1800Z...DISSIPATED
FORECASTER REINHART
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