711
WTPZ42 KNHC 202052
TCDEP2
HURRICANE NORMA DISCUSSION NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172023
300 PM MDT FRI OCT 20 2023
AFTER A BRIEF PERIOD OF WEAKENING EARLIER TODAY, DATA FROM THE AIR
FORCE HURRICANE HUNTERS THIS AFTERNOON INDICATE THAT NORMA HAS
STRENGTHENED BACK TO A MAJOR HURRICANE. THE AIRCRAFT DATA SHOWED
MAXIMUM 700-MB FLIGHT-LEVEL WINDS OF 124 KT, WITH PEAK SFMR WINDS OF
104 KT IN THE NORTHEAST QUADRANT. BASED ON THESE DATA, THE INITIAL
INTENSITY IS RAISED TO 105 KT. THE EYEWALL IS OPEN TO THE SOUTHEAST
BASED ON AIRCRAFT REPORTS. THE EYE SIGNATURE HAS BECOME BETTER
DEFINED OVER THE PAST FEW HOURS IN RADAR DATA FROM LOS CABOS,
MEXICO, AS NEW BURSTS OF INTENSE INNER CORE CONVECTION HAVE
DEVELOPED. THE RADAR DATA SHOW THAT THE OUTER RAINBANDS OF NORMA ARE
BEGINNING TO SPREAD OVER SOUTHERN PORTIONS OF BAJA CALIFORNIA SUR.
IN THE SHORT TERM, THE RENEWED INNER CORE OF NORMA COULD ALLOW THE
HURRICANE TO RESIST SOME OF THE NEGATIVE INFLUENCES OF SOUTHERLY
SHEAR AND DRIER AIR IN THE SURROUNDING ENVIRONMENT. THE UPDATED NHC
FORECAST STILL SHOWS SOME WEAKENING BUT IS HIGHER THAN THE PREVIOUS
ONE DURING THE FIRST 24-36 H OF THE FORECAST, BASED LARGELY ON THE
HIGHER INITIAL INTENSITY. LAND INTERACTION WITH THE BAJA CALIFORNIA
PENINSULA, ALONG WITH THE PREVIOUSLY DESCRIBED NEGATIVE FACTORS,
SHOULD INDUCE A MORE STEADY WEAKENING TREND THROUGH EARLY NEXT WEEK
WHILE NORMA APPROACHES MAINLAND MEXICO.
SCATTEROMETER DATA AND AIRCRAFT FIXES SHOW THAT NORMA HAS MOVED
SLIGHTLY LEFT-OF-TRACK TODAY, AND ITS INITIAL MOTION IS 330/7 KT.
THE HURRICANE IS EXPECTED TO TURN TOWARD THE NORTH-NORTHWEST AND
NORTH DURING THE NEXT DAY OR SO WHILE IT MOVES BETWEEN A MID- TO
UPPER-LEVEL TROUGH TO ITS NORTHWEST AND A MID-LEVEL RIDGE TO ITS
EAST. THIS WILL BRING THE CENTER OF NORMA OVER THE SOUTHERN TIP OF
BAJA CALIFORNIA SUR WITHIN THE HURRICANE WARNING ON SATURDAY. THE
TRACK MODELS HAVE AGAIN TRENDED WESTWARD THIS CYCLE, AND THE UPDATED
NHC FORECAST IS NUDGED IN THAT DIRECTION DURING THE NEXT 24-36 H.
THEN, THE MODELS GENERALLY AGREE THAT NORMA WILL TURN NORTHEASTWARD
AND APPROACH THE COAST OF SINALOA IN WESTERN MEXICO, ALTHOUGH THERE
ARE STILL NOTABLE SPEED DIFFERENCES BETWEEN THE VARIOUS TRACK
MODELS. THIS PORTION OF THE NHC FORECAST IS SIMILAR TO THE PREVIOUS
ONE, ALTHOUGH A BIT SLOWER BASED ON THE LATEST CONSENSUS AIDS. NORMA
IS FORECAST TO MOVE INLAND ALONG THE COAST OF SINALOA ON MONDAY AND
QUICKLY DISSIPATE THEREAFTER OVER THE TERRAIN OF WESTERN MEXICO.
KEY MESSAGES:
1. NORMA IS EXPECTED TO BRING HURRICANE CONDITIONS AND A DANGEROUS
STORM SURGE TO PORTIONS OF THE FAR SOUTHERN BAJA CALIFORNIA
PENINSULA WITHIN THE HURRICANE WARNING AREA ON SATURDAY.
PREPARATIONS TO PROTECT LIFE AND PROPERTY SHOULD BE RUSHED TO
COMPLETION.
2. HEAVY RAINS FROM NORMA WILL BEGIN TO IMPACT THE FAR SOUTHERN
PORTIONS OF BAJA CALIFORNIA SUR TODAY AND CONTINUE THROUGH SUNDAY,
WITH HEAVY RAINS REACHING SINALOA ON SATURDAY. THIS RAINFALL WILL
PRODUCE FLASH AND URBAN FLOODING, ALONG WITH POSSIBLE MUDSLIDES IN
AREAS OF HIGHER TERRAIN.
3. NORMA IS FORECAST TO APPROACH THE WEST COAST OF MEXICO AS A
TROPICAL STORM ON SUNDAY AND SUNDAY NIGHT, AND A TROPICAL STORM
WATCH IS IN EFFECT FOR A PORTION OF THAT AREA.
FORECAST POSITIONS AND MAX WINDS
INIT 20/2100Z 20.1N 109.8W 105 KT 120 MPH
12H 21/0600Z 21.2N 110.0W 100 KT 115 MPH
24H 21/1800Z 22.6N 110.1W 85 KT 100 MPH
36H 22/0600Z 23.4N 109.7W 70 KT 80 MPH
48H 22/1800Z 23.9N 109.0W 60 KT 70 MPH
60H 23/0600Z 24.2N 108.1W 50 KT 60 MPH
72H 23/1800Z 24.6N 107.1W 35 KT 40 MPH...INLAND
96H 24/1800Z...DISSIPATED
FORECASTER REINHART
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