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Issued at 300 AM CST Thu Sep 26 2024 000 WTPZ45 KNHC 260835 TCDEP5 Tropical Storm John Discussion Number 14 NWS National Hurricane Center Miami FL EP102024 300 AM CST Thu Sep 26 2024 Recent TROPICS/TMS and SSMIS microwave passes indicated an improved inner core with a 70 percent closed small eye feature. The UW-CIMSS objective intensity guidance ranges from 56 to 65 kt, and the latest SATCON analysis indicated an intensity of 61 kt. The subjective satellite estimates from TAFB and SAB are 65 and 55 kt, respectively. The initial intensity is set at 60 kt using a blend of these data. The ocean sea surface temperatures are very warm, and the shear is low, and there is ample moisture in the low to mid-portions of the atmosphere for John to quickly strengthen before the cyclone moves over the coast on Friday. The UW-CIMSS AI RI index and the SHIPS statistical-dynamical RI model both continue to show increasing chances of John quickly strengthening during the next 24 hrs and the NHC intensity forecast follows suit and shows a peak of 85 kt before landfall. The initial motion is estimated to be west-northwestward, or 285/3 kt and is being steered by a mid-tropospheric ridge centered over Northern Mexico. John should continue in this general motion is expected to continue today, followed by a gradual turn to the northwest by this evening. On the forecast track, the center of John is forecast to approach and move along over Northern Mexico. John should continue in this general motion is expected to continue today, followed by a gradual turn to the northwest by this evening. On the forecast track, the center of John is forecast to approach and move along the coast of southwestern Mexico or just inland on Friday. The official track forecast is adjusted to a little to the left of the previous one and follows a compromise of the skilled HCCA consensus model and the ECMWF global model, which has been performing the best with this system.the coast of southwestern Mexico or just inland on Friday. The official track forecast is adjusted to a little to the left of the previous one and follows a compromise of the skilled HCCA consensus model and the ECMWF global model, which has been performing the best with this system. The wind radii have been adjusted for this advisory, and was based on a 0426 UTC METOP-C scatterometer overpass. 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. Tropical Storm 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, Oaxaca and Michoacan. 2. John is forecast to strengthen to a hurricane before landfall, and a Hurricane Warning is in effect along the coastline of southwestern Mexico, where tropical storm conditions could begin during the next few hours. Tropical Storm Warnings are also in effect for portions of the area and has been extended westward to Manzanillo. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 17.1N 102.5W 60 KT 70 MPH 12H 26/1800Z 17.2N 102.6W 75 KT 85 MPH 24H 27/0600Z 17.8N 103.0W 85 KT 100 MPH 36H 27/1800Z 18.8N 103.6W 45 KT 50 MPH 48H 28/0600Z 19.7N 104.7W 30 KT 35 MPH 60H 28/1800Z 20.2N 106.2W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 29/0600Z...DISSIPATED $$ Forecaster Roberts

...TROPICAL STORM WARNING EXTENDED WESTWARD... ...CATASTROPHIC LIFE-THREATENING FLASH FLOODING AND MUDSLIDES CONTINUE OVER PORTIONS OF SOUTHERN MEXICO... As of 3:00 AM CST Thu Sep 26 the center of John was located near 17.1, -102.5 with movement WNW at 3 mph. The minimum central pressure was 982 mb with maximum sustained winds of about 70 mph.

Issued at 0900 UTC THU SEP 26 2024 000 WTPZ25 KNHC 260833 TCMEP5 TROPICAL STORM JOHN FORECAST/ADVISORY NUMBER 14 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 0900 UTC THU SEP 26 2024 TROPICAL STORM CENTER LOCATED NEAR 17.1N 102.5W AT 26/0900Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 3 KT ESTIMATED MINIMUM CENTRAL PRESSURE 982 MB MAX SUSTAINED WINDS 60 KT WITH GUSTS TO 75 KT. 50 KT....... 0NE 15SE 15SW 10NW. 34 KT....... 40NE 120SE 60SW 50NW. 12 FT SEAS.. 0NE 330SE 240SW 30NW. 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 17.1N 102.5W AT 26/0900Z AT 26/0600Z CENTER WAS LOCATED NEAR 17.0N 102.3W FORECAST VALID 26/1800Z 17.2N 102.6W MAX WIND 75 KT...GUSTS 90 KT. 64 KT... 10NE 0SE 0SW 0NW. 50 KT... 20NE 15SE 15SW 10NW. 34 KT... 40NE 120SE 60SW 50NW. FORECAST VALID 27/0600Z 17.8N 103.0W MAX WIND 85 KT...GUSTS 105 KT. 64 KT... 10NE 15SE 10SW 10NW. 50 KT... 20NE 30SE 30SW 20NW. 34 KT... 60NE 150SE 120SW 60NW. FORECAST VALID 27/1800Z 18.8N 103.6W MAX WIND 45 KT...GUSTS 55 KT. 34 KT... 30NE 90SE 60SW 30NW. FORECAST VALID 28/0600Z 19.7N 104.7W MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 28/1800Z 20.2N 106.2W...POST-TROP/REMNT LOW MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 29/0600Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 17.1N 102.5W INTERMEDIATE PUBLIC ADVISORY...WTNT35 KNHC/MIATCPEP5...AT 26/1200Z NEXT ADVISORY AT 26/1500Z $$ FORECASTER ROBERTS

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0316 AM CDT Thu Sep 26 2024 Valid 291200Z - 041200Z ...DISCUSSION... The upper low over the OH Valley will weaken and become an open wave early next week. Meanwhile, upper troughing across the east will be reinforced through midweek by a shortwave trough developing east/southeast across the Great Lakes. A surface cold front will develop east/southeast across much of the Plains and Midwest through Day 6/Tue. However stronger deep-layer flow will remain displaced well to the north and behind the front. Meanwhile, low-amplitude upper ridging will prevail across the Southwest/Four Corner, while a series of shortwave troughs migrate through more progressive northern stream flow near the international border in the vicinity of the Pacific Northwest and northern Rockies. Overall severe thunderstorm potential appears low during the Day 4-8 period. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Thu Sep 26 2024 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Synopsis... The closed mid/upper low will progress east across the OH/TN Valleys on Saturday, weakening with time. Enhanced southwesterly flow will prevail on the eastern periphery of this system, from parts of northern FL to the Mid-Atlantic. A moist boundary layer will also prevail across parts of the Southeast and Mid-Atlantic vicinity. However, dry midlevels and poor lapse rates will limit instability across much of the region, with the exception being parts of the FL Peninsula. Isolated thunderstorms will be possible across the FL Peninsula, but poor lapse rates, weak instability and only modest effective shear will limit severe thunderstorm potential. ..Leitman.. 09/26/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Thu Sep 26 2024 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Synopsis... The closed mid/upper low will progress east across the OH/TN Valleys on Saturday, weakening with time. Enhanced southwesterly flow will prevail on the eastern periphery of this system, from parts of northern FL to the Mid-Atlantic. A moist boundary layer will also prevail across parts of the Southeast and Mid-Atlantic vicinity. However, dry midlevels and poor lapse rates will limit instability across much of the region, with the exception being parts of the FL Peninsula. Isolated thunderstorms will be possible across the FL Peninsula, but poor lapse rates, weak instability and only modest effective shear will limit severe thunderstorm potential. ..Leitman.. 09/26/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Thu Sep 26 2024 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Synopsis... The closed mid/upper low will progress east across the OH/TN Valleys on Saturday, weakening with time. Enhanced southwesterly flow will prevail on the eastern periphery of this system, from parts of northern FL to the Mid-Atlantic. A moist boundary layer will also prevail across parts of the Southeast and Mid-Atlantic vicinity. However, dry midlevels and poor lapse rates will limit instability across much of the region, with the exception being parts of the FL Peninsula. Isolated thunderstorms will be possible across the FL Peninsula, but poor lapse rates, weak instability and only modest effective shear will limit severe thunderstorm potential. ..Leitman.. 09/26/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Thu Sep 26 2024 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Synopsis... The closed mid/upper low will progress east across the OH/TN Valleys on Saturday, weakening with time. Enhanced southwesterly flow will prevail on the eastern periphery of this system, from parts of northern FL to the Mid-Atlantic. A moist boundary layer will also prevail across parts of the Southeast and Mid-Atlantic vicinity. However, dry midlevels and poor lapse rates will limit instability across much of the region, with the exception being parts of the FL Peninsula. Isolated thunderstorms will be possible across the FL Peninsula, but poor lapse rates, weak instability and only modest effective shear will limit severe thunderstorm potential. ..Leitman.. 09/26/2024 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0152 AM CDT Thu Sep 26 2024 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Saturday. ...Synopsis... The closed mid/upper low will progress east across the OH/TN Valleys on Saturday, weakening with time. Enhanced southwesterly flow will prevail on the eastern periphery of this system, from parts of northern FL to the Mid-Atlantic. A moist boundary layer will also prevail across parts of the Southeast and Mid-Atlantic vicinity. However, dry midlevels and poor lapse rates will limit instability across much of the region, with the exception being parts of the FL Peninsula. Isolated thunderstorms will be possible across the FL Peninsula, but poor lapse rates, weak instability and only modest effective shear will limit severe thunderstorm potential. ..Leitman.. 09/26/2024 Read more