679
WTPZ45 KNHC 261439
TCDEP5
HURRICANE JOHN DISCUSSION NUMBER 15
NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024
900 AM CST THU SEP 26 2024
JOHN CONTINUES TO DEPICT A SMALL INNER CORE, WITH EARLIER MICROWAVE
IMAGES DEPICTING A SMALL EYE FEATURE. SINCE THAT MICROWAVE PASS, THE
EYE FEATURE HAS BECOME MORE PREVALENT ON INFRARED IMAGERY. THE
UW-CIMSS OBJECTIVE INTENSITY GUIDANCE RANGES FROM 65 TO 75 KT. THE
SUBJECTIVE SATELLITE ESTIMATES FROM TAFB AND SAB ARE BOTH 65 KT,
RESPECTIVELY. USING A BLEND OF THE INTENSITY ESTIMATES AND THE
CONTINUED IMPROVED SATELLITE DEPICTION, THE INTENSITY IS SET AT 65
KT FOR THIS ADVISORY.
THE HURRICANE IS ESTIMATED TO BE MOVING NORTHWESTWARD AT 310/5 KT.
THE OFFICIAL FORECAST IS SHIFTED SLIGHTLY TO THE RIGHT IN THE NEAR
TERM, WHICH FOLLOWS RECENT SATELLITE TRENDS AND LIES NEAR THE LATEST
HCCA CONSENSUS AID. ON THE FORECAST TRACK, THE CENTER OF JOHN IS
FORECAST TO APPROACH AND MOVE ALONG THE COAST OF SOUTHWESTERN MEXICO
OR JUST INLAND LATER TODAY. HOWEVER, SOME OF THE GLOBAL MODEL FIELDS
DO LINGER THE SYSTEM OFFSHORE NEAR THE COAST A LITTLE LONGER,
PARTICULARLY THE ECMWF GLOBAL MODEL. IN THE LONG TERM, A TURN BACK
TO THE WEST-NORTHWEST IS ANTICIPATED AS THE SYSTEM WEAKENS AND IS
STEERED BY THE RIDGE OVER NORTHERN MEXICO.
THE OVERALL ENVIRONMENT REMAINS FAVORABLE FOR JOHN TO CONTINUE TO
STRENGTHEN UNTIL LANDFALL WITH VERY WARM SEA SURFACE TEMPERATURES,
LOW WIND SHEAR, ABUNDANT MOISTURE THROUGHOUT ALL LEVELS OF THE
ATMOSPHERE. THE LATEST NHC INTENSITY FORECAST CONTINUES TO CALL FOR
STRENGTHENING UP UNTIL LANDFALL AND SHOWS A PEAK INTENSITY OF 75 KT,
WHICH IS SLIGHTLY LOWER THAN PREVIOUS INTENSITY PEAK DUE TO THE
LATEST FORECAST SHOWING THE SYSTEM MOVING INLAND A LITTLE FASTER
THAN THE PREVIOUS FORECAST.
JOHN HAS VERY LARGE RAIN SHIELD AND FLOODING IMPACTS WILL EXTEND
WELL OUTSIDE WHERE THE SYSTEM MAKES LANDFALL. IT CANNOT BE
EMPHASIZED ENOUGH THAT CATASTROPHIC LIFE-THREATENING FLASH FLOODING
AND MUDSLIDES ARE EXPECTED TO CONTINUE THROUGH THE END OF THE WEEK
FOR PORTIONS OF THE MEXICAN STATES OF GUERRERO, OAXACA AND
MICHOACAN.
KEY MESSAGES:
1. HURRICANE JOHN WILL BRING ADDITIONAL VERY HEAVY RAINFALL TO
COASTAL PORTIONS OF SOUTHWEST MEXICO THROUGH FRIDAY. THE ADDITIONAL
RAINFALL TOTALS WILL BE FALLING ACROSS AREAS THAT HAVE RECEIVED VERY
HEAVY RAINFALL AMOUNTS OVER THE PAST FEW DAYS. THIS HEAVY RAINFALL
WILL LIKELY CAUSE SIGNIFICANT AND CATASTROPHIC LIFE-THREATENING
FLASH FLOODING AND MUDSLIDES TO THE MEXICAN STATES OF GUERRERO AND
MICHOACáN.
2. JOHN IS FORECAST TO CONTINUE STRENGTHENING UP UNTIL LANDFALL, AND
A HURRICANE WARNING IS IN EFFECT ALONG THE COASTLINE OF SOUTHWESTERN
MEXICO, WHERE TROPICAL STORM CONDITIONS ARE IMMINENT. TROPICAL
STORM WARNINGS ARE ALSO IN EFFECT FOR PORTIONS OF THE AREA AND
TROPICAL STORM ARE ONGOING.
FORECAST POSITIONS AND MAX WINDS
INIT 26/1500Z 17.5N 102.7W 65 KT 75 MPH
12H 27/0000Z 18.0N 102.9W 75 KT 85 MPH...NEAR COAST
24H 27/1200Z 18.6N 103.4W 45 KT 50 MPH...INLAND
36H 28/0000Z 19.2N 104.2W 30 KT 35 MPH...INLAND
48H 28/1200Z 19.8N 105.4W 30 KT 35 MPH...POST-TROP/REMNT LOW
60H 29/0000Z 20.5N 107.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 29/1200Z...DISSIPATED
FORECASTER KELLY
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