603
WTPZ42 KNHC 211450
TCDEP2
HURRICANE NORMA DISCUSSION NUMBER 16
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172023
900 AM MDT SAT OCT 21 2023
RADAR DATA FROM LOS CABOS, MEXICO, SHOW THE CENTER OF NORMA IS
SITUATED JUST WEST-SOUTHWEST OF CABO SAN LUCAS THIS MORNING. SURFACE
OBSERVATIONS INDICATE THAT HURRICANE AND TROPICAL STORM CONDITIONS
ARE SPREADING OVER SOUTHERN PORTIONS OF BAJA CALIFORNIA SUR WITHIN
THE WARNING AREAS. EARLIER PASSIVE MICROWAVE IMAGES AND RECENT RADAR
DATA INDICATE CONVECTION IN THE SOUTHERN PORTION OF NORMA'S INNER
CORE HAS ERODED. THE HURRICANE IS ALSO VERTICALLY TILTED DUE TO
SOUTHERLY SHEAR, WITH THE LOW-LEVEL CENTER DISPLACED SLIGHTLY SOUTH
OF THE MID-LEVEL CENTER. THESE STRUCTURAL CHANGES SUGGEST WEAKENING
HAS OCCURRED, WHICH IS CONSISTENT WITH THE LATEST SUBJECTIVE AND
OBJECTIVE INTENSITY ESTIMATES FROM TAFB, SAB, AND UW-CIMSS. BASED ON
THE BLEND OF THOSE ESTIMATES, THE INITIAL INTENSITY IS LOWERED TO 85
KT FOR THIS ADVISORY.
NORMA IS MOVING JUST WEST OF DUE NORTH (355/7 KT) THIS MORNING. THE
HURRICANE IS EXPECTED TO MAKE LANDFALL IN THE HURRICANE WARNING AREA
THIS AFTERNOON, CROSS THE SOUTHERN PORTION OF BAJA CALIFORNIA SUR
TONIGHT, AND EMERGE OVER THE SOUTHERN GULF OF CALIFORNIA ON SUNDAY.
THEN, THE WEAKENING CYCLONE SHOULD TURN TOWARD THE NORTHEAST AND
EAST-NORTHEAST AND SLOWLY APPROACH THE COAST OF SINALOA IN WESTERN
MEXICO ON SUNDAY NIGHT INTO EARLY MONDAY. THE UPDATED NHC TRACK
FORECAST SHOWS A SLIGHTLY MORE GRADUAL TURN IN THE NEAR TERM AND
LIES SLIGHTLY WEST OF THE PREVIOUS ONE. NORMA IS FORECAST TO MOVE
INLAND BY EARLY MONDAY AND DISSIPATE OVER THE RUGGED TERRAIN OF
WESTERN MEXICO BY TUESDAY.
LESS FAVORABLE ENVIRONMENTAL CONDITIONS (INCREASING SOUTHWESTERLY
SHEAR AND REDUCED MID-LEVEL MOISTURE) AND LAND INTERACTION WITH THE
BAJA CALIFORNIA PENINSULA SHOULD CAUSE NORMA TO CONTINUE WEAKENING
DURING THE NEXT COUPLE OF DAYS. THIS IS CONSISTENT WITH THE
DETERIORATING SATELLITE STRUCTURE OF NORMA AND SUPPORTED BY ALL OF
THE LATEST DYNAMICAL AND STATISTICAL GUIDANCE. THE UPDATED NHC
FORECAST IS LOWER THAN THE PREVIOUS ADVISORY, FOLLOWING THE
MULTI-MODEL CONSENSUS TRENDS, BUT LIES ON THE HIGHER END OF THE
GUIDANCE ENVELOPE. NORMA IS STILL FORECAST TO REACH THE WEST COAST
OF MEXICO BY EARLY MONDAY AS A TROPICAL STORM.
KEY MESSAGES:
1. NORMA IS EXPECTED TO BRING LIFE-THREATENING HURRICANE CONDITIONS
AND A DANGEROUS STORM SURGE TO PORTIONS OF THE FAR SOUTHERN BAJA
CALIFORNIA PENINSULA WITHIN THE HURRICANE WARNING AREA TODAY AND
TONIGHT.
2. HEAVY RAINS FROM NORMA WILL CONTINUE TO IMPACT SOUTHERN PORTIONS
OF BAJA CALIFORNIA SUR THROUGH SUNDAY, WITH HEAVY RAINS REACHING
SINALOA LATER TODAY, CONTINUING THROUGH MONDAY. THIS RAINFALL WILL
PRODUCE FLASH AND URBAN FLOODING, ALONG WITH MUDSLIDES IN AREAS OF
HIGHER TERRAIN.
3. NORMA IS FORECAST TO APPROACH THE WEST COAST OF MEXICO AS A
TROPICAL STORM ON SUNDAY NIGHT AND MONDAY, AND A TROPICAL STORM
WARNING IS IN EFFECT FOR A PORTION OF THAT AREA.
FORECAST POSITIONS AND MAX WINDS
INIT 21/1500Z 22.7N 110.3W 85 KT 100 MPH
12H 22/0000Z 23.4N 110.1W 75 KT 85 MPH...INLAND
24H 22/1200Z 24.1N 109.4W 60 KT 70 MPH...OVER WATER
36H 23/0000Z 24.5N 108.6W 50 KT 60 MPH
48H 23/1200Z 24.7N 107.7W 40 KT 45 MPH...INLAND
60H 24/0000Z 25.1N 106.8W 25 KT 30 MPH...POST-TROP/INLAND
72H 24/1200Z...DISSIPATED
FORECASTER REINHART
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