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Issued at 500 PM EDT Mon Sep 23 2024 000 WTNT34 KNHC 232052 TCPAT4 BULLETIN Potential Tropical Cyclone Nine Advisory Number 2 NWS National Hurricane Center Miami FL AL092024 500 PM EDT Mon Sep 23 2024 ...DISTURBANCE FORECAST TO STRENGTHEN SIGNIFICANTLY DURING THE NEXT FEW DAYS... ...TROPICAL STORM WATCHES ISSUED FOR THE LOWER FLORIDA KEYS AND DRY TORTUGAS... SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...18.1N 82.2W ABOUT 105 MI...170 KM SW OF GRAND CAYMAN ABOUT 315 MI...510 KM SE OF THE WESTERN TIP OF CUBA MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 7 MPH...11 KM/H MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: A Tropical Storm Watch has been issued for the Dry Tortugas and the Lower Florida Keys south of the Seven Mile Bridge. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Watch is in effect for... * Cabo Catoche to Tulum, Mexico * Cuban province of Pinar del Rio A Tropical Storm Warning is in effect for... * Rio Lagartos to Tulum, Mexico * Cuban provinces of Artemisa, and Pinar del Rio, and the Isle of Youth A Tropical Storm Watch is in effect for... * Dry Tortugas * Lower Keys south of the Seven Mile Bridge A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 24 to 36 hours. A Hurricane Watch means that hurricane conditions are possible within the watch area. A watch is typically issued 48 hours before the anticipated first occurrence of tropical-storm-force winds, conditions that make outside preparations difficult or dangerous. A Tropical Storm Watch means that tropical storm conditions are possible within the watch area, generally within 48 hours. Interests along the northeastern Gulf Coast, including the Florida Panhandle and portions of the Florida west coast, should monitor the progress of this system. Additional watches or warnings will likely be required tonight and Tuesday. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 500 PM EDT (2100 UTC), the disturbance was centered near latitude 18.1 North, longitude 82.2 West. The system is moving toward the north-northwest near 7 mph (11 km/h). A northwestward motion is expected on Tuesday and Tuesday night, followed by a faster northward to north-northeastward motion on Wednesday and Thursday. On the forecast track, the center of the system is forecast to move across the northwestern Caribbean Sea through Tuesday night, and then over the eastern Gulf of Mexico on Wednesday and Thursday. Maximum sustained winds have increased to near 35 mph (55 km/h) with higher gusts. Strengthening is expected during the next few days, and the system is forecast to become a hurricane on Wednesday and continue strengthening on Thursday as it moves across the eastern Gulf of Mexico. * Formation chance through 48 hours...high...90 percent. * Formation chance through 7 days...high...90 percent. The estimated minimum central pressure is 1003 mb (29.62 inches). HAZARDS AFFECTING LAND ---------------------- Key Messages for Potential Tropical Cyclone Nine can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and WMO header WTNT44 KNHC and on the web at hurricanes.gov/text/MIATCDAT4.shtml RAINFALL: Potential Tropical Cyclone Nine is expected to produce total rain accumulations of 4 to 8 inches over western Cuba and the Cayman Islands with isolated totals around 12 inches. Over the eastern Yucatan Peninsula, 2 to 4 inches of rain is expected with isolated totals over 6 inches. This rainfall brings a risk of considerable flooding. Over the Southeastern U.S., Potential Tropical Cyclone Nine is expected to produce total rain accumulations of 3 to 6 inches with isolated totals around 10 inches, bringing a risk of flooding, some of which could be considerable. For a complete depiction of forecast rainfall associated with Potential Tropical Cyclone Nine, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_at4.shtml?rainqpf and the Flash Flood Risk graphic at hurricanes.gov/graphics_at4.shtml?ero STORM SURGE: The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline. The water could reach the following heights above ground somewhere in the indicated areas if the peak surge occurs at the time of high tide... Dry Tortugas...1-3 ft Florida Keys...1-3 ft Storm surge could raise water levels by as much as 2 to 4 feet above normal tide levels in areas of onshore winds along the southern coast of Pinar del Rio, Cuba, including the Isle of Youth. Storm surge could raise water levels by as much as 2 to 4 feet above ground level in areas of onshore winds within the warning area along the east coast of the Yucatan Peninsula. WIND: Hurricane conditions are possible within the watch areas in Cuba and Mexico by early Wednesday. Tropical storm conditions are expected in the warning areas in Cuba and Mexico beginning on Tuesday. Tropical storm conditions are possible in the watch area beginning on Wednesday. SURF: Swells generated by the system will affect the southern coast of Cuba and the Yucatan Peninsula of Mexico during the next couple of days. Swells will spread northward toward the west coast of Florida and the northeastern Gulf Coast on Wednesday and Thursday. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next intermediate advisory at 800 PM EDT. Next complete advisory at 1100 PM EDT. $$ Forecaster Reinhart

...DISTURBANCE FORECAST TO STRENGTHEN SIGNIFICANTLY DURING THE NEXT FEW DAYS... ...TROPICAL STORM WATCHES ISSUED FOR THE LOWER FLORIDA KEYS AND DRY TORTUGAS... As of 5:00 PM EDT Mon Sep 23 the center of Nine was located near 18.1, -82.2 with movement NNW at 7 mph. The minimum central pressure was 1003 mb with maximum sustained winds of about 35 mph.

Issued at 2100 UTC MON SEP 23 2024 858 WTNT24 KNHC 232051 TCMAT4 POTENTIAL TROPICAL CYCLONE NINE FORECAST/ADVISORY NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL AL092024 2100 UTC MON SEP 23 2024 POTENTIAL TROP CYCLONE CENTER LOCATED NEAR 18.1N 82.2W AT 23/2100Z POSITION ACCURATE WITHIN 40 NM PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 345 DEGREES AT 6 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1003 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 18.1N 82.2W AT 23/2100Z AT 23/1800Z CENTER WAS LOCATED NEAR 17.9N 81.9W FORECAST VALID 24/0600Z 19.0N 83.0W...TROPICAL CYCLONE MAX WIND 35 KT...GUSTS 45 KT. 34 KT... 70NE 80SE 0SW 0NW. FORECAST VALID 24/1800Z 19.9N 84.2W MAX WIND 45 KT...GUSTS 55 KT. 34 KT...140NE 130SE 60SW 60NW. FORECAST VALID 25/0600Z 21.1N 85.4W MAX WIND 55 KT...GUSTS 65 KT. 50 KT... 40NE 30SE 20SW 30NW. 34 KT...180NE 160SE 80SW 110NW. FORECAST VALID 25/1800Z 23.0N 86.0W MAX WIND 75 KT...GUSTS 90 KT. 64 KT... 30NE 30SE 20SW 20NW. 50 KT... 60NE 60SE 40SW 40NW. 34 KT...200NE 190SE 110SW 130NW. FORECAST VALID 26/0600Z 25.4N 85.5W MAX WIND 90 KT...GUSTS 110 KT. 50 KT... 90NE 90SE 50SW 50NW. 34 KT...220NE 210SE 140SW 140NW. FORECAST VALID 26/1800Z 28.9N 84.5W MAX WIND 100 KT...GUSTS 120 KT. 50 KT... 90NE 100SE 50SW 40NW. 34 KT...200NE 220SE 140SW 130NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 125 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 27/1800Z 35.5N 84.5W...POST-TROP/INLAND MAX WIND 30 KT...GUSTS 40 KT. OUTLOOK VALID 28/1800Z 39.5N 88.5W...POST-TROP/INLAND MAX WIND 20 KT...GUSTS 30 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 18.1N 82.2W INTERMEDIATE PUBLIC ADVISORY...WTNT34 KNHC/MIATCPAT4...AT 24/0000Z NEXT ADVISORY AT 24/0300Z $$ FORECASTER REINHART

5-Day Uncertainty Track last updated Mon, 23 Sep 2024 20:50:07 GMT


Wind Speed Probabilities last updated Mon, 23 Sep 2024 21:28:56 GMT

Issued at 300 PM CST Mon Sep 23 2024 000 WTPZ45 KNHC 232049 TCDEP5 Hurricane John Discussion Number 6 NWS National Hurricane Center Miami FL EP102024 300 PM CST Mon Sep 23 2024 John continues to rapidly strengthen. The latest subjective Dvorak intensity estimates range from 65 to 77 kt, while the latest objective intensity estimates are a little higher, in the 79 to 90 kt range. On infrared satellite imagery, the area of cold cloud tops continues to grow, and the inner core is becoming more symmetric. The latest visible images have shown hints of a small eye, that has become a little more apparent in the last few hours. Based on the above data and recent satellite trends, the initial intensity is increased to 85 kt, making John a category 2 hurricane. Environmental parameters continue to be ripe for additional rapid intensification, with very warm ocean temperatures, weak vertical wind shear and a moist atmosphere. The only potential limiting factor could be how John might interact with the mountainous topography of Mexico as the hurricane approaches the coastline. The DSHIPS and LGEM statistical intensity models remain at the higher end of the guidance envelope and show John becoming a major hurricane as it approaches the coast. The EC SHIPS Rapid Intensity Index is depicting a high likelihood of continued rapid intensification over next 12 hours. The latest NHC forecast is near the high end of the intensity guidance and continues to show John strengthening to a 105-kt hurricane. It is possible that John could peak even higher than shown below between the 12 h forecast point and when it reaches the coast. John continues to move due northward, now at 5 kt. The current motion and the latest model guidance has again necessitated a westward track shift to the NHC forecast. Given the updated track forecast, the government of Mexico has extended the hurricane warning westward. KEY MESSAGES: 1. John is expected to continue rapidly intensifying, and is forecast to become a major hurricane before the center reaches the coast of southern Mexico within the Hurricane Warning area tonight or early Tuesday. Damaging hurricane-force winds and a life-threatening storm surge are expected within portions of the hurricane warning area. 2. John will bring very heavy rainfall to coastal portions of southern Mexico through this 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. FORECAST POSITIONS AND MAX WINDS INIT 23/2100Z 15.5N 98.5W 85 KT 100 MPH 12H 24/0600Z 16.0N 98.3W 105 KT 120 MPH 24H 24/1800Z 16.5N 98.3W 65 KT 75 MPH...INLAND 36H 25/0600Z 16.7N 98.4W 30 KT 35 MPH...POST-TROP/INLAND 48H 25/1800Z...DISSIPATED $$ Forecaster Hagen

Issued at 2100 UTC MON SEP 23 2024 000 FOPZ15 KNHC 232048 PWSEP5 HURRICANE JOHN WIND SPEED PROBABILITIES NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 2100 UTC MON SEP 23 2024 AT 2100Z THE CENTER OF HURRICANE JOHN WAS LOCATED NEAR LATITUDE 15.5 NORTH...LONGITUDE 98.5 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 85 KTS ...100 MPH...155 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 18Z MON 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 18Z MON 06Z TUE 18Z TUE 06Z WED 18Z WED 18Z THU 18Z FRI PERIODS TO TO TO TO TO TO TO 06Z TUE 18Z TUE 06Z WED 18Z WED 18Z THU 18Z FRI 18Z SAT FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT ZIHUATANEJO 34 X 2( 2) 1( 3) X( 3) X( 3) X( 3) X( 3) 15N 100W 34 1 3( 4) 5( 9) X( 9) X( 9) X( 9) X( 9) ACAPULCO 34 2 11(13) 4(17) X(17) X(17) X(17) X(17) ACAPULCO 50 X 2( 2) 1( 3) X( 3) X( 3) X( 3) X( 3) ACAPULCO 64 X X( X) 1( 1) X( 1) X( 1) X( 1) X( 1) P MALDONADO 34 88 5(93) X(93) X(93) X(93) X(93) X(93) P MALDONADO 50 49 18(67) 1(68) X(68) X(68) X(68) X(68) P MALDONADO 64 16 19(35) 3(38) X(38) X(38) X(38) X(38) P ANGEL 34 1 6( 7) 4(11) X(11) X(11) X(11) X(11) HUATULCO 34 X 1( 1) 2( 3) X( 3) X( 3) X( 3) X( 3) 15N 95W 34 X 2( 2) 1( 3) X( 3) X( 3) X( 3) X( 3) $$ FORECASTER HAGEN

Issued at 300 PM CST Mon Sep 23 2024 000 WTPZ35 KNHC 232048 TCPEP5 BULLETIN Hurricane John Advisory Number 6 NWS National Hurricane Center Miami FL EP102024 300 PM CST Mon Sep 23 2024 ...JOHN RAPIDLY STRENGTHENS TO A CATEGORY 2 HURRICANE... ...DAMAGING HURRICANE-FORCE WINDS, LIFE-THREATENING STORM SURGE AND FLASH FLOODING ARE EXPECTED IN PORTIONS OF SOUTHERN MEXICO... SUMMARY OF 300 PM CST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...15.5N 98.5W ABOUT 55 MI...90 KM S OF PUNTA MALDONADO MEXICO ABOUT 95 MI...155 KM WSW OF PUERTO ESCONDIDO MEXICO MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H PRESENT MOVEMENT...N OR 0 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...973 MB...28.74 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has issued a Hurricane Warning from west of Punta Maldonado to east of Acapulco. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Hurricane Warning is in effect for... * East of Acapulco to Bahias de Huatulco A Tropical Storm Warning is in effect for... * East of Bahias de Huatulco to Salina Cruz A Hurricane Warning means that hurricane conditions are expected somewhere within the warning area, in this case within the next 12 to 24 hours. Preparations to protect life and property should be rushed to completion. A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning area, in this case within the next 12 to 24 hours. For storm information specific to your area, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 300 PM CST (2100 UTC), the center of Hurricane John was located near latitude 15.5 North, longitude 98.5 West. John is moving toward the north near 6 mph (9 km/h). A slow motion to the north or north-northeast is expected during the next 24 hours. On the forecast track, the center of John is forecast to move inland along the coast of southern Mexico tonight or early Tuesday. Maximum sustained winds have increased to near 100 mph (155 km/h) with higher gusts. John is a category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale. Rapid strengthening is forecast to continue, and John is expected to become a major hurricane as it approaches the coast of southern Mexico. Hurricane-force winds extend outward up to 10 miles (20 km) from the center and tropical-storm-force winds extend outward up to 45 miles (75 km). The estimated minimum central pressure is 973 mb (28.74 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, 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. 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. For a complete depiction of forecast rainfall associated with Hurricane John, please see the National Weather Service Storm Total Rainfall Graphic, available at hurricanes.gov/graphics_ep5.shtml?rainqpf STORM SURGE: A life-threatening storm surge is expected to produce significant coastal flooding near and to the east of where the center makes landfall. Near the coast, the surge will be accompanied by large and destructive waves. WIND: Hurricane conditions are expected to reach the coast within the hurricane warning area tonight. Winds are expected to first reach tropical storm strength later this afternoon, making outside preparations difficult or dangerous. Preparations to protect life and property should be rushed to completion. Tropical storm conditions are expected to first reach the coast within the tropical storm warning area this evening. SURF: Swells associated with John are forecast to continue affecting the coast of southern Mexico during the next couple of days, with the potential for dangerous surf and rip currents much of the week. Please see local statements for more information. NEXT ADVISORY ------------- Next intermediate advisory at 600 PM CST. Next complete advisory at 900 PM CST. $$ Forecaster Hagen

Issued at 2100 UTC MON SEP 23 2024 000 WTPZ25 KNHC 232047 TCMEP5 HURRICANE JOHN FORECAST/ADVISORY NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102024 2100 UTC MON SEP 23 2024 HURRICANE CENTER LOCATED NEAR 15.5N 98.5W AT 23/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTH OR 0 DEGREES AT 5 KT ESTIMATED MINIMUM CENTRAL PRESSURE 973 MB MAX SUSTAINED WINDS 85 KT WITH GUSTS TO 105 KT. 64 KT....... 10NE 10SE 0SW 10NW. 50 KT....... 20NE 20SE 15SW 20NW. 34 KT....... 40NE 40SE 30SW 40NW. 12 FT SEAS.. 45NE 75SE 75SW 45NW. 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 15.5N 98.5W AT 23/2100Z AT 23/1800Z CENTER WAS LOCATED NEAR 15.2N 98.4W FORECAST VALID 24/0600Z 16.0N 98.3W MAX WIND 105 KT...GUSTS 130 KT. 64 KT... 10NE 10SE 10SW 10NW. 50 KT... 20NE 20SE 20SW 20NW. 34 KT... 50NE 60SE 60SW 40NW. FORECAST VALID 24/1800Z 16.5N 98.3W...INLAND MAX WIND 65 KT...GUSTS 80 KT. 64 KT... 0NE 10SE 10SW 0NW. 50 KT... 15NE 20SE 20SW 15NW. 34 KT... 30NE 60SE 80SW 30NW. FORECAST VALID 25/0600Z 16.7N 98.4W...POST-TROP/INLAND MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 25/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 15.5N 98.5W INTERMEDIATE PUBLIC ADVISORY...WTNT35 KNHC/MIATCPEP5...AT 24/0000Z NEXT ADVISORY AT 24/0300Z $$ FORECASTER HAGEN

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0250 PM CDT Mon Sep 23 2024 Valid 232000Z - 241200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHERN ARKANSAS INTO THE LOWER OHIO AND TENNESSEE RIVER VALLEYS... ...SUMMARY... Isolated strong to severe thunderstorms are possible this afternoon into evening from the Ozarks into parts of the Tennessee and lower Ohio Valleys. ...20z Update... The previous forecast remains on track with only minor adjustments needed based on recent observations and trends in guidance. Latest surface observations and upper-air analyses show the gradual organization of a surface low over northern AR/southern MO. The frontal boundary draped from southeast MO into the upper OH River Valley has begun to stall and is expected to gradually advance north through the evening hours. VWP observations along the frontal zone currently show relatively straight low-level hodographs, but helicity should slowly improve through the 20-03 UTC period as isentropic ascent along the front increases. As a result, the convective environment should become more favorable for organized convection - particularly during the 22-03 UTC period across far southeast MO into far southern IL and western KY. Latest high-res guidance suggests that storms developing along an approaching cold front across north-central AR will intensify as they migrate east towards this zone and should pose the primary severe threat this evening. However, loosely-organized thunderstorms recently developing within the mid-MS River Valley cast some uncertainty onto this scenario due to the potential for overturning portions of the downstream warm sector. This early convection may see improving organization in the coming hours as mid-level flow slowly improves late this afternoon, but limit storm longevity over the past hour cast some uncertainty onto the propensity for severe storms. Regardless, this stalled/warm frontal boundary will still present the best corridor for a more focused severe event through the evening hours, including the potential for a tornado or two. As such, the 2% risk probabilities have been expanded east into western KY. Consideration was given for 15% wind probabilities through this corridor, but confidence in storm mode and coverage remains too limited given the aforementioned concerns. Farther east across southern KY and TN, the forecast remains on track. See MCD #2097 for details regarding recent convective trends. ..Moore.. 09/23/2024 .PREV DISCUSSION... /ISSUED 1143 AM CDT Mon Sep 23 2024/ ...Ozarks to TN/OH Valleys and southern Appalachians... A positive-tilt upper trough will influence the region, with a general increase in relatively strong deep-layer southwesterly winds. Severe storms are possible this afternoon, particularly and initially across the Ozarks including far south-central to southeast Missouri, as well as far northern Arkansas and far southern Illinois. This will be in vicinity of a weak surface wave and a northward-shifting warm front as lingering morning convection along/north of the Ohio River abates and shifts eastward. Increasingly strong deep-layer winds could support some supercells. Some hail is possible given the buoyancy/deep-layer wind profiles, although mid-level lapse rates are not steep. Locally damaging winds may also occur, with some potential for a tornado or two mainly near the warm front. Although uncertainties linger regarding destabilization and the magnitude of the severe risk later this afternoon, portions of southeast Missouri and far southern Illinois will continue to be reevaluated into mid-afternoon (20Z update) for a potential risk upgrade. Farther east, isolated to scattered thunderstorms will probably develop near the ridge tops of the southern Appalachians and adjacent parts of the Carolinas Piedmont this afternoon. Moist low levels coupled with heating will result in around 1000 J/kg MLCAPE. Some modest multicell organization may occur due to adequately strong upper-level westerly flow, with a few locally damaging wind gusts a possibility. Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 PM CDT Mon Sep 23 2024 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is uncertain, but limited, on Wednesday. ...Synopsis... The upper-level trough across the Midwest into the Mid-South is expected to evolve into a strong trough in the lower Great Lakes/Northeast and a cut-off low in the Ozarks. A surface cold front is expected to be positioned from near the upper Ohio Valley southward into Mid-South and westward into the southern Plains. In the Gulf of Mexico, current NHC forecasts show a hurricane moving north-northeastward in parts of the eastern Gulf. ...Western/central New York... A narrow warm sector may exist ahead of the cold front. Subtle forcing from the trough to the north may promote storm development during the afternoon. Given the potential for cloud cover/precipitation early in the day, along with the strongest mid-level ascent arriving during the evening, uncertainty is too high for severe probabilities. ...Mid-South/Southeast... Strong mid-level flow around the eventual cut-off low could allow for some storm organization near the cold front. There is a fairly strong signal for precipitation to be ongoing during morning and into the afternoon. Surface-based destabilization is at best uncertain and perhaps not very likely. No severe probabilities will be added. ...Portions of the Florida Peninsula... Given the forecast track of the tropical cyclone by NHC and available model guidance, there is some potential for low-level wind fields to increase in parts of the southern/central Florida Peninsula towards Thursday morning. Given the trough to the north of the expected hurricane and the uncertainty of the exact position of the system and any related outer convective bands, will continue to withhold low tornado probabilities. ..Wendt.. 09/23/2024 Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 PM CDT Mon Sep 23 2024 Valid 251200Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorm potential is uncertain, but limited, on Wednesday. ...Synopsis... The upper-level trough across the Midwest into the Mid-South is expected to evolve into a strong trough in the lower Great Lakes/Northeast and a cut-off low in the Ozarks. A surface cold front is expected to be positioned from near the upper Ohio Valley southward into Mid-South and westward into the southern Plains. In the Gulf of Mexico, current NHC forecasts show a hurricane moving north-northeastward in parts of the eastern Gulf. ...Western/central New York... A narrow warm sector may exist ahead of the cold front. Subtle forcing from the trough to the north may promote storm development during the afternoon. Given the potential for cloud cover/precipitation early in the day, along with the strongest mid-level ascent arriving during the evening, uncertainty is too high for severe probabilities. ...Mid-South/Southeast... Strong mid-level flow around the eventual cut-off low could allow for some storm organization near the cold front. There is a fairly strong signal for precipitation to be ongoing during morning and into the afternoon. Surface-based destabilization is at best uncertain and perhaps not very likely. No severe probabilities will be added. ...Portions of the Florida Peninsula... Given the forecast track of the tropical cyclone by NHC and available model guidance, there is some potential for low-level wind fields to increase in parts of the southern/central Florida Peninsula towards Thursday morning. Given the trough to the north of the expected hurricane and the uncertainty of the exact position of the system and any related outer convective bands, will continue to withhold low tornado probabilities. ..Wendt.. 09/23/2024 Read more