784
WTPZ42 KNHC 221437
TCDEP2
TROPICAL STORM NORMA DISCUSSION NUMBER 20
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172023
900 AM MDT SUN OCT 22 2023
BURSTS OF DEEP CONVECTION HAVE BEEN WRAPPING AROUND THE NORTHERN
PORTION OF NORMA'S CENTER OVERNIGHT AND INTO THE MORNING. MICROWAVE
SATELLITE IMAGERY FROM AN AMSR2 0931 UTC PASS ALSO SHOWED A DECENT
CURVED BAND AROUND THE NORTHERN SIDE OF THE CIRCULATION. THE
INITIAL INTENSITY IS HELD AT 50 KT BASED ON THE PREVIOUS CYCLE'S
SATELLITE WIND DATA AND IS SIMILAR TO THE SUBJECTIVE DVORAK CURRENT
INTENSITY ESTIMATES OF T3.0/45 KT FROM TAFB AND SAB. NORMA IS
EXPECTED TO MAINTAIN ITS INTENSITY FOR THE NEXT 12 H OR SO. AFTER
THE STORM MOVES INLAND OVER MAINLAND MEXICO, RAPID WEAKENING AND
DISSIPATION OVER THE HIGH TERRAIN IS PREDICTED TO OCCUR WITHIN A DAY
OR SO.
NORMA IS STILL MOVING NORTH-NORTHEASTWARD AT ABOUT 4 KT. THE MOST
RECENT MODEL GUIDANCE SUGGESTS NORMA WILL MAKE A TURN TO THE
NORTHEAST SHORTLY AS THE STORM CROSSES THE GULF OF CALIFORNIA. THERE
REMAINS A FAIRLY LARGE SPREAD IN THE TRACK GUIDANCE, WITH THE GFS ON
THE SOUTHERN SIDE AND ECMWF ON THE NORTHERN SIDE OF THE ENVELOPE.
THE LATEST NHC TRACK FORECAST HAS SHIFTED NORTHWARD BY ABOUT 15 N MI
FROM THE PREVIOUS ADVISORY, LIKELY DUE TO THE RECENT
NORTH-NORTHEASTWARD MOTION. REGARDLESS OF THE EXACT LANDFALL
LOCATION OF THE CENTER, HEAVY RAINFALL AND GUSTY WINDS ARE EXPECTED
TO SPREAD ALONG THE COAST OF THE MEXICAN STATE OF SINAOLA AND INLAND
THROUGH TONIGHT AND INTO TOMORROW MORNING.
KEY MESSAGES:
1. HEAVY RAINS FROM NORMA WILL CONTINUE TO IMPACT SINALOA INTO
MONDAY. RAINFALL WILL CONTINUE TO DIMINISH ACROSS THE SOUTHERN
PORTIONS OF BAJA CALIFORNIA SUR EARLY THIS MORNING. THIS RAINFALL
WILL PRODUCE FLASH AND URBAN FLOODING, ALONG WITH MUDSLIDES IN AREAS
OF HIGHER TERRAIN.
2. TROPICAL STORM CONDITIONS WILL CONTINUE THROUGH THIS AFTERNOON
WITHIN PORTIONS OF THE TROPICAL STORM WARNING AREA OVER THE SOUTHERN
BAJA CALIFORNIA PENINSULA.
3. TROPICAL STORM CONDITIONS ARE EXPECTED TO SPREAD ONSHORE ALONG
PORTIONS OF THE WEST COAST OF MAINLAND MEXICO WITHIN THE TROPICAL
STORM WARNING AREA THROUGH TONIGHT.
FORECAST POSITIONS AND MAX WINDS
INIT 22/1500Z 24.7N 109.6W 50 KT 60 MPH
12H 23/0000Z 25.2N 109.1W 50 KT 60 MPH
24H 23/1200Z 25.7N 108.2W 30 KT 35 MPH...INLAND
36H 24/0000Z...DISSIPATED
FORECASTER BUCCI
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