National Hurricane Center (NHC) Pacific Map

000
ABPZ20 KNHC 241754
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 AM PDT Tue Sep 24 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Active Systems:
The National Hurricane Center has issued its last advisory on
Tropical Storm John, dissipated inland over southern Mexico.

Offshore of Southern Mexico:
A trough of low pressure, partially associated with the remnants of
John, is producing a large area of showers and thunderstorms along
the coast of southern Mexico. Environmental conditions appear
conducive for some development of this system and a tropical
depression could form in the next couple of days or so, depending on
if it stays over water. Interests in southern Mexico should monitor
the progress of this system. Regardless of development, this system
is expected to produce heavy rainfall and the potential for flash
flooding and mudslides over portions of southern Mexico this week.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...medium...50 percent.

$$
Forecaster Bucci/Cangialosi

5-Day Uncertainty Track last updated Tue, 24 Sep 2024 17:49:30 GMT


Wind Speed Probabilities last updated Tue, 24 Sep 2024 17:49:31 GMT

Issued at 1200 PM CST Tue Sep 24 2024 000 WTPZ45 KNHC 241748 TCDEP5 Remnants Of John Special Discussion Number 10 NWS National Hurricane Center Miami FL EP102024 1200 PM CST Tue Sep 24 2024 Satellite images and surface observations indicate that the low-level center of John has dissipated. Therefore, the system is no longer a tropical cyclone, and this is the last NHC advisory. However, an elongated trough partly associated with John's remnants appears to be forming off the coast of southern and southwestern Mexico. This system is now included in the Tropical Weather Outlook with a medium chance of development. Regardless of whether or not John re-forms or a new system develops, heavy rainfall with the potential for significant flooding is likely during the next several days over portions of southern and southwestern Mexico, especially in areas of high terrain. FORECAST POSITIONS AND MAX WINDS INIT 24/1800Z 17.7N 100.6W 30 KT 35 MPH 12H 25/0000Z...DISSIPATED $$ Forecaster Cangialosi/Bucci

Issued at 1800 UTC TUE SEP 24 2024 000 FOPZ15 KNHC 241747 PWSEP5 REMNANTS OF JOHN SPECIAL WIND SPEED PROBABILITIES NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 1800 UTC TUE SEP 24 2024 AT 1800Z THE REMNANTS OF JOHN WERE LOCATED NEAR LATITUDE 17.7 NORTH ...LONGITUDE 100.6 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS... 35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 12Z TUE AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 12Z TUE 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT PERIODS TO TO TO TO TO TO TO 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT 12Z SUN FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT ZIHUATANEJO 34 7 1( 8) X( 8) X( 8) X( 8) X( 8) X( 8) $$ FORECASTER CANGIALOSI

Issued at 1200 PM CST Tue Sep 24 2024 000 WTPZ35 KNHC 241747 TCPEP5 BULLETIN Remnants Of John Special Advisory Number 10 NWS National Hurricane Center Miami FL EP102024 1200 PM CST Tue Sep 24 2024 ...JOHN DISSIPATES OVER MEXICO... ...HEAVY RAINS STILL EXPECTED TO CAUSE FLASH FLOODING OVER SOUTHERN AND SOUTHWESTERN MEXICO FOR SEVERAL MORE DAYS... SUMMARY OF 1200 PM CST...1800 UTC...INFORMATION ----------------------------------------------- LOCATION...17.7N 100.6W ABOUT 70 MI...115 KM NW OF ACAPULCO MEXICO MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...WNW OR 300 DEGREES AT 3 MPH...6 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has discontinued all Tropical Storm Warnings. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 1200 PM CST (1800 UTC), the remnants of John were located inland near latitude 17.7 North, longitude 100.6 West. The remnants are moving toward the west-northwest near 3 mph (6 km/h). Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. The estimated minimum central pressure is 1004 mb (29.65 inches). HAZARDS AFFECTING LAND ---------------------- RAINFALL: Through Thursday, the remnants of John are expected to produce 6 to 12 inches of rain with isolated totals around 15 inches across the coastal areas of Chiapas. In areas along and near the Oaxaca coast to southeast Guerrero, between 10 and 20 inches of rain with isolated totals near 30 inches can be expected through Thursday. NEXT ADVISORY ------------- This is the last public advisory issued by the National Hurricane Center on this system. Information on possible tropical cyclone development off the coast of Mexico will be contained in the Tropical Weather Outlook issued by the National Hurricane Center. $$ Forecaster Cangialosi/Bucci

...JOHN DISSIPATES OVER MEXICO... ...HEAVY RAINS STILL EXPECTED TO CAUSE FLASH FLOODING OVER SOUTHERN AND SOUTHWESTERN MEXICO FOR SEVERAL MORE DAYS... As of 12:00 PM CST Tue Sep 24 the center of John was located near 17.7, -100.6 with movement WNW at 3 mph. The minimum central pressure was 1004 mb with maximum sustained winds of about 35 mph.

Issued at 1800 UTC TUE SEP 24 2024 000 WTPZ25 KNHC 241747 TCMEP5 REMNANTS OF JOHN SPECIAL FORECAST/ADVISORY NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 1800 UTC TUE SEP 24 2024 REMNANTS OF CENTER LOCATED NEAR 17.7N 100.6W AT 24/1800Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 3 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1004 MB MAX SUSTAINED WINDS 30 KT WITH GUSTS TO 40 KT. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 17.7N 100.6W AT 24/1800Z AT 24/1200Z CENTER WAS LOCATED NEAR 17.7N 100.3W FORECAST VALID 25/0000Z..DISSIPATED THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS SYSTEM $$ FORECASTER CANGIALOSI/BUCCI

Issued at 900 AM CST Tue Sep 24 2024 628 WTPZ45 KNHC 241435 TCDEP5 Tropical Storm John Discussion Number 9 NWS National Hurricane Center Miami FL EP102024 900 AM CST Tue Sep 24 2024 John has been rapidly weakening since it moved inland last night, and the maximum sustained winds are now estimated to be around 35 kt. The storm still has a well-defined mid-level center, but surface observations suggest that the low-level circulation is less defined and could be opening into a trough. A strong band of thunderstorms to the east of the estimated center continues to produce heavy rains across portions of southern Mexico. There is quite a bit of uncertainty in the future of John. One possibility is that the storm dissipates over Mexico, with a trough or low reforming back offshore and lingering in that location for much of the rest of the week. The other possibility is that John itself hangs on as a tropical depression or storm. For now, the official forecast generally follows the previous scenario and shows John weakening to a tropical depression later today and lingering near the coast of southern and southwestern Mexico until the end of the week. It is hoped that additional data and model runs later today will help provide some clarity on the system's future. Even though the future of John is uncertain, there is high confidence that heavy rains will continue in portions of southern and southwestern Mexico during the next couple of days. See the Key Messages below for additional information on that hazard. KEY MESSAGES: 1. Slow-moving John will continue to bring very heavy rainfall to coastal portions of southern and southwestern Mexico through the upcoming week. This heavy rainfall will likely cause significant and possibly catastrophic, life-threatening flash flooding and mudslides to the Mexican States of Chiapas, Oaxaca, and southeast Guerrero, particularly in areas near the coast and along the up-slope portion of areas of higher terrain. 2. John could still produce tropical storm conditions for the next couple of hours in the tropical storm warning area. FORECAST POSITIONS AND MAX WINDS INIT 24/1500Z 17.7N 100.5W 35 KT 40 MPH...INLAND 12H 25/0000Z 17.7N 101.1W 30 KT 35 MPH...INLAND 24H 25/1200Z 17.3N 101.1W 30 KT 35 MPH...OVER WATER 36H 26/0000Z 17.1N 100.8W 30 KT 35 MPH 48H 26/1200Z 17.4N 100.7W 25 KT 30 MPH...INLAND 60H 27/0000Z 17.7N 100.8W 25 KT 30 MPH...INLAND 72H 27/1200Z...DISSIPATED $$ Forecaster Cangialosi

5-Day Uncertainty Track last updated Tue, 24 Sep 2024 15:05:13 GMT


Wind Speed Probabilities last updated Tue, 24 Sep 2024 15:28:54 GMT

...LIFE-THREATENING FLASH FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO DURING THE NEXT FEW DAYS... As of 9:00 AM CST Tue Sep 24 the center of John was located near 17.7, -100.5 with movement NW at 12 mph. The minimum central pressure was 1001 mb with maximum sustained winds of about 40 mph.

Issued at 1500 UTC TUE SEP 24 2024 223 FOPZ15 KNHC 241434 PWSEP5 TROPICAL STORM JOHN WIND SPEED PROBABILITIES NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 1500 UTC TUE SEP 24 2024 AT 1500Z THE CENTER OF TROPICAL STORM JOHN WAS LOCATED NEAR LATITUDE 17.7 NORTH...LONGITUDE 100.5 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 35 KTS...40 MPH...65 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 12Z TUE AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 12Z TUE 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT PERIODS TO TO TO TO TO TO TO 00Z WED 12Z WED 00Z THU 12Z THU 12Z FRI 12Z SAT 12Z SUN FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT L CARDENAS 34 1 1( 2) 1( 3) X( 3) 1( 4) X( 4) X( 4) ZIHUATANEJO 34 11 2(13) 2(15) X(15) 1(16) X(16) X(16) ACAPULCO 34 1 X( 1) 2( 3) 3( 6) 1( 7) X( 7) X( 7) $$ FORECASTER CANGIALOSI

Issued at 900 AM CST Tue Sep 24 2024 222 WTPZ35 KNHC 241434 TCPEP5 BULLETIN Tropical Storm John Advisory Number 9 NWS National Hurricane Center Miami FL EP102024 900 AM CST Tue Sep 24 2024 ...LIFE-THREATENING FLASH FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO DURING THE NEXT FEW DAYS... SUMMARY OF 900 AM CST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...17.7N 100.5W ABOUT 70 MI...110 KM NW OF ACAPULCO MEXICO MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Punta Maldonado to Zihuatanejo A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case over the next few hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 900 AM CST (1500 UTC), the center of Tropical Storm John was located near latitude 17.7 North, longitude 100.5 West. John is moving toward the northwest near 12 mph (19 km/h). Little motion is expected during the next few days. Maximum sustained winds are near 40 mph (65 km/h) with higher gusts. Slow weakening is expected during the next couple of days. Tropical-storm-force winds extend outward up to 80 miles (130 km) from the center. The estimated minimum central pressure is 1001 mb (29.56 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for John can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDEP5 and WMO header WTPZ45 KNHC and on the web at hurricanes.gov/text/MIATCDEP5.shtml RAINFALL: Through Thursday, Tropical Storm John is expected to produce 6 to 12 inches of rain with isolated totals around 15 inches across the coastal areas of Chiapas. In areas along and near the Oaxaca coast to southeast Guerrero, between 10 and 20 inches of rain with isolated totals near 30 inches can be expected through Thursday. For a complete depiction of forecast rainfall associated with Tropical Storm John, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep5.shtml?rainqpf WIND: Tropical storm conditions are ongoing within portions of the tropical storm warning area and should continue for the next couple of hours. Wind speeds atop and on the windward sides of hills and mountains are often up to 30 percent stronger than the near-surface winds indicated in this advisory, and in some elevated locations could be even greater. SURF: Swells associated with John are forecast to continue affecting the coast of southern Mexico during the next day or so, with the potential for dangerous surf and rip currents. Please see local statements for more information. NEXT ADVISORY ------------- Next intermediate advisory at 1200 PM CST. Next complete advisory at 300 PM CST. $$ Forecaster Cangialosi

Issued at 1500 UTC TUE SEP 24 2024 085 WTPZ25 KNHC 241434 TCMEP5 TROPICAL STORM JOHN FORECAST/ADVISORY NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 1500 UTC TUE SEP 24 2024 TROPICAL STORM CENTER LOCATED NEAR 17.7N 100.5W AT 24/1500Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE NORTHWEST OR 310 DEGREES AT 10 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1001 MB MAX SUSTAINED WINDS 35 KT WITH GUSTS TO 45 KT. 34 KT....... 0NE 70SE 70SW 0NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 17.7N 100.5W AT 24/1500Z AT 24/1200Z CENTER WAS LOCATED NEAR 17.7N 100.3W FORECAST VALID 25/0000Z 17.7N 101.1W...INLAND MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 25/1200Z 17.3N 101.1W...OVER WATER MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 26/0000Z 17.1N 100.8W MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 26/1200Z 17.4N 100.7W...INLAND MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 27/0000Z 17.7N 100.8W...INLAND MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 27/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 17.7N 100.5W INTERMEDIATE PUBLIC ADVISORY...WTNT35 KNHC/MIATCPEP5...AT 24/1800Z NEXT ADVISORY AT 24/2100Z $$ FORECASTER CANGIALOSI

5-Day Uncertainty Track last updated Tue, 24 Sep 2024 14:36:52 GMT


Wind Speed Probabilities last updated Tue, 24 Sep 2024 14:36:52 GMT

...LIFE-THREATENING FLASH FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHERN AND SOUTHWESTERN MEXICO DURING THE NEXT FEW DAYS... As of 9:00 AM CST Tue Sep 24 the center of John was located near 17.7, -100.5 with movement NW at 12 mph. The minimum central pressure was 1001 mb with maximum sustained winds of about 40 mph.

000
ABPZ20 KNHC 241153
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Tue Sep 24 2024

For the eastern North Pacific...east of 140 degrees west longitude:

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm John, located just inland near the coast of southern Mexico.

Tropical cyclone formation is not expected over the next 7 days.

$$
Forecaster Bucci

5-Day Uncertainty Track last updated Tue, 24 Sep 2024 11:51:31 GMT


Wind Speed Probabilities last updated Tue, 24 Sep 2024 09:29:09 GMT

Issued at 600 AM CST Tue Sep 24 2024 000 WTPZ35 KNHC 241146 TCPEP5 BULLETIN Tropical Storm John Intermediate Advisory Number 8A NWS National Hurricane Center Miami FL EP102024 600 AM CST Tue Sep 24 2024 ...LIFE-THREATENING FLASH FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHERN MEXICO DURING THE NEXT FEW DAYS... SUMMARY OF 600 AM CST...1200 UTC...INFORMATION ---------------------------------------------- LOCATION...17.7N 100.3W ABOUT 60 MI...100 KM NNW OF ACAPULCO MEXICO MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H PRESENT MOVEMENT...NW OR 305 DEGREES AT 8 MPH...13 KM/H MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has adjusted the Tropical Storm Warning westward from Punta Maldonado to Zihuatanejo. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Punta Maldonado to Zihuatanejo A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case over the next few hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 600 AM CST (1200 UTC), the center of Tropical Storm John was located near latitude 17.7 North, longitude 100.3 West. John is moving toward the northwest near 8 mph (13 km/h). A slow westward motion is expected during the next few days. Maximum sustained winds are near 50 mph (85 km/h) with higher gusts. Continued rapid weakening is anticipated, and John is expected to become a tropical depression later today. Tropical-storm-force winds extend outward up to 45 miles (75 km) from the center. The estimated minimum central pressure is 999 mb (29.50 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for John can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDEP5 and WMO header WTPZ45 KNHC and on the web at hurricanes.gov/text/MIATCDEP5.shtml RAINFALL: Through Thursday, Tropical Storm John is expected to produce 6 to 12 inches of rain with isolated totals around 15 inches across the coastal areas of Chiapas. In areas along and near the Oaxaca coast to southeast Guerrero, between 10 and 20 inches of rain with isolated totals near 30 inches can be expected through Thursday. For a complete depiction of forecast rainfall associated with Tropical Storm John, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep5.shtml?rainqpf WIND: Tropical storm conditions are ongoing within portions of the tropical storm warning area and should continue for the next few hours. Wind speeds atop and on the windward sides of hills and mountains are often up to 30 percent stronger than the near-surface winds indicated in this advisory, and in some elevated locations could be even greater. SURF: Swells associated with John are forecast to continue affecting the coast of southern Mexico during the next day or so, with the potential for dangerous surf and rip currents. Please see local statements for more information. NEXT ADVISORY ------------- Next complete advisory at 900 AM CST. $$ Forecaster Cangialosi

...LIFE-THREATENING FLASH FLOODING POSSIBLE ACROSS PORTIONS OF SOUTHERN MEXICO DURING THE NEXT FEW DAYS... As of 6:00 AM CST Tue Sep 24 the center of John was located near 17.7, -100.3 with movement NW at 8 mph. The minimum central pressure was 999 mb with maximum sustained winds of about 50 mph.

Issued at 300 AM CST Tue Sep 24 2024 523 WTPZ45 KNHC 240852 TCDEP5 Tropical Storm John Discussion Number 8 NWS National Hurricane Center Miami FL EP102024 300 AM CST Tue Sep 24 2024 John moved inland at around 0315 UTC as a 105 kt Category 3 Hurricane. Since that time, the the storm has apparently turned more leftward and remains just inland, skirting the southern coast of Mexico. While surface observations have been sparse, my best guess is that the storm recently passed just to the north of Acapulco, where the airport earlier reported tropical-storm-force wind gusts and west winds as the pressure dropped to 998 mb. Assuming the small core has continued to quickly weaken, John is being downgraded to a tropical storm, and the initial intensity is 60 kt this advisory. Following fixes from earlier microwave and more recent geostationary satellite imagery, John now appears to be moving northwestward at 310/7 kt. The track forecast, which has been problematic with John from the start, is just as difficult now. John has continued to deviate westward of the previous forecast track and is now moving roughly parallel to the coast of Mexico. To make matters worse, a decent chunk of the of the global models guidance (ECMWF, UKMET) and hurricane regional models (HWRF, HMON) suggest the circulation could continue turning westward and attempt to re-emerge over the Eastern Pacific. Even the GFS and CMC solutions, which appear to dissipate the surface circulation inland over Mexico, show the mid-level circulation persisting and drifting back offshore, leading to the development of a new low-level circulation. Because it is becoming distinctly possible that John does not move far enough inland to dissipate entirely, and the aforementioned continued leftward trends, the latest NHC track forecast is altered quite a bit form the prior forecast, and now shows the possibility that John, albeit as a tropical depression, moving back offshore as it becomes tangled in the larger monsoonal flow. By 72 h, most of the track guidance shows the system moving back inland. The updated track forecast is roughly in between the HCCA and ECMWF trackers, and is of very low confidence given John's track history. It also remains possible the system could dissipate later today if it moves further inland. Intensity-wise, John should continue to rapidly weaken as long as it remains onshore, and the NHC intensity forecast shows the tropical cyclone weakening to a tropical depression later today. However, the new NHC forecast now maintains the system as a depression and does not show dissipation beyond 24 h given the latest track forecast taking the system along the coast of Mexico and not far enough inland to completely dissipate. Some of the models (notably the ECMWF) attempt to also re-intensify John as it gets far enough back offshore, but given the large changes made on this forecast cycle, the NHC intensity will not show that solution quite yet. Even if John remains inland, larger-scale moist monsoonal southeasterly flow will persist along the southern coast of Mexico, likely contributing to catastrophic rainfall both along the coast and inland over the up-slope portion of the mountainous terrain. This is a very dangerous life-threatening flooding scenario. KEY MESSAGES: 1. Tropical Storm John could still producing tropical storm conditions for the next few hours in the tropical storm warning area. 2. Slow-moving John will bring very heavy rainfall to coastal portions of southwest Mexico through the upcoming week. This heavy rainfall will likely cause significant and possibly catastrophic, life-threatening flash flooding and mudslides to the Mexican States of Chiapas, Oaxaca, and southeast Guerrero, particularly in areas near the coast and along the up-slope portion of areas of higher terrain. FORECAST POSITIONS AND MAX WINDS INIT 24/0900Z 17.3N 100.0W 60 KT 70 MPH...INLAND 12H 24/1800Z 17.4N 100.8W 30 KT 35 MPH...INLAND 24H 25/0600Z 17.0N 101.0W 30 KT 35 MPH...OVER WATER 36H 25/1800Z 16.7N 100.9W 30 KT 35 MPH 48H 26/0600Z 16.9N 100.6W 30 KT 35 MPH 60H 26/1800Z 17.4N 100.7W 25 KT 30 MPH...INLAND 72H 27/0600Z 18.1N 101.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 28/0600Z...DISSIPATED $$ Forecaster Papin