Aggregator

Issued at 1500 UTC SAT AUG 09 2025 000 WTPZ24 KNHC 091440 TCMEP4 TROPICAL STORM IVO FORECAST/ADVISORY NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092025 1500 UTC SAT AUG 09 2025 TROPICAL STORM CENTER LOCATED NEAR 21.0N 112.7W AT 09/1500Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST-NORTHWEST OR 290 DEGREES AT 5 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1001 MB MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT. 50 KT....... 15NE 0SE 0SW 15NW. 34 KT....... 30NE 30SE 20SW 30NW. 4 M SEAS.... 60NE 30SE 0SW 60NW. 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 21.0N 112.7W AT 09/1500Z AT 09/1200Z CENTER WAS LOCATED NEAR 20.9N 112.4W FORECAST VALID 10/0000Z 21.4N 113.8W MAX WIND 45 KT...GUSTS 55 KT. 34 KT... 30NE 30SE 20SW 30NW. FORECAST VALID 10/1200Z 21.9N 115.7W MAX WIND 40 KT...GUSTS 50 KT. 34 KT... 30NE 20SE 0SW 30NW. FORECAST VALID 11/0000Z 22.4N 117.6W...POST-TROPICAL MAX WIND 35 KT...GUSTS 45 KT. 34 KT... 20NE 0SE 0SW 20NW. FORECAST VALID 11/1200Z 22.6N 119.7W...POST-TROP/REMNT LOW MAX WIND 30 KT...GUSTS 40 KT. FORECAST VALID 12/0000Z 22.7N 121.9W...POST-TROP/REMNT LOW MAX WIND 25 KT...GUSTS 35 KT. FORECAST VALID 12/1200Z 22.6N 124.3W...POST-TROP/REMNT LOW MAX WIND 20 KT...GUSTS 30 KT. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 100 NM ON DAY 4 AND 125 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 13/1200Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 21.0N 112.7W NEXT ADVISORY AT 09/2100Z $$ FORECASTER BERG

Issued at 1500 UTC SAT AUG 09 2025 000 FOPZ14 KNHC 091439 PWSEP4 TROPICAL STORM IVO WIND SPEED PROBABILITIES NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092025 1500 UTC SAT AUG 09 2025 AT 1500Z THE CENTER OF TROPICAL STORM IVO WAS LOCATED NEAR LATITUDE 21.0 NORTH...LONGITUDE 112.7 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 50 KTS...60 MPH...95 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 SAT 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 SAT 00Z SUN 12Z SUN 00Z MON 12Z MON 12Z TUE 12Z WED PERIODS TO TO TO TO TO TO TO 00Z SUN 12Z SUN 00Z MON 12Z MON 12Z TUE 12Z WED 12Z THU FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT $$ FORECASTER BERG

Issued at 800 AM MST Sat Aug 09 2025 000 WTPZ34 KNHC 091439 TCPEP4 BULLETIN Tropical Storm Ivo Advisory Number 12 NWS National Hurricane Center Miami FL EP092025 800 AM MST Sat Aug 09 2025 ...IVO FORECAST TO WEAKEN OVER COLDER WATERS... SUMMARY OF 800 AM MST...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...21.0N 112.7W ABOUT 220 MI...360 KM SW OF THE SOUTHERN TIP OF BAJA CALIFORNIA MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H PRESENT MOVEMENT...WNW OR 290 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 800 AM MST (1500 UTC), the center of Tropical Storm Ivo was located near latitude 21.0 North, longitude 112.7 West. Ivo is moving toward the west-northwest near 6 mph (9 km/h). A faster motion toward the west-northwest and then west is expected during the next few days. Maximum sustained winds are near 60 mph (95 km/h) with higher gusts. Weakening is forecast during the next few days, and Ivo is likely to become post-tropical by late Sunday. Tropical-storm-force winds extend outward up to 35 miles (55 km) from the center. The estimated minimum central pressure is 1001 mb (29.56 inches). HAZARDS AFFECTING LAND ---------------------- SURF: Swells generated by Ivo will continue to affect the southern portion of the Baja California peninsula during the next day or so. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. NEXT ADVISORY ------------- Next complete advisory at 200 PM MST. $$ Forecaster Berg

...IVO FORECAST TO WEAKEN OVER COLDER WATERS... As of 8:00 AM MST Sat Aug 09 the center of Ivo was located near 21.0, -112.7 with movement WNW at 6 mph. The minimum central pressure was 1001 mb with maximum sustained winds of about 60 mph.

WW 0580 Status Updates
STATUS REPORT ON WW 580 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 NW ALO TO 25 WSW MCW TO 25 E FRM. WW 580 WILL BE ALLOWED TO EXPIRE AT 091700Z. ..SQUITIERI..08/09/25 ATTN...WFO...DMX... STATUS REPORT FOR WS 580 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC033-081-189-195-091700- IA . IOWA COUNTIES INCLUDED ARE CERRO GORDO HANCOCK WINNEBAGO WORTH THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0580 Status Updates
STATUS REPORT ON WW 580 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 30 NW ALO TO 25 WSW MCW TO 25 E FRM. WW 580 WILL BE ALLOWED TO EXPIRE AT 091700Z. ..SQUITIERI..08/09/25 ATTN...WFO...DMX... STATUS REPORT FOR WS 580 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC033-081-189-195-091700- IA . IOWA COUNTIES INCLUDED ARE CERRO GORDO HANCOCK WINNEBAGO WORTH THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 580 SEVERE TSTM IA 091105Z - 091700Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 580 NWS Storm Prediction Center Norman OK 605 AM CDT Sat Aug 9 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western and Central Iowa * Effective this Saturday morning from 605 AM until NOON CDT. * Primary threats include... Scattered damaging winds likely with isolated significant gusts to 80 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...A small but intense bowing cluster should continue moving east-northeastward this morning while producing scattered to numerous severe/damaging winds. Isolated gusts up to 70-80 mph appear possible. Additional thunderstorms will also develop along a cold front across parts of western into central Iowa. This activity should also pose mainly a severe/damaging wind threat, but isolated hail may also occur. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 35 miles northwest of Mason City IA to 35 miles southwest of Des Moines IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU0). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 579... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 70 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 25035. ...Gleason Read more

MD 1911 CONCERNING SEVERE THUNDERSTORM WATCH 580... FOR PORTIONS OF IA INTO SOUTHEAST MN AND FAR WEST-CENTRAL WI
Mesoscale Discussion 1911 NWS Storm Prediction Center Norman OK 0729 AM CDT Sat Aug 09 2025 Areas affected...portions of IA into southeast MN and far west-central WI Concerning...Severe Thunderstorm Watch 580... Valid 091229Z - 091430Z The severe weather threat for Severe Thunderstorm Watch 580 continues. SUMMARY...Severe thunderstorms producing damaging wind gusts will persist across portions of western into north-central Iowa this morning. DISCUSSION...Severe gusts continue with the cluster of storms ongoing across west-central IA this morning. Radar trends have shown some downward trend in velocity strength as well as a somewhat more disorganized presentation in reflectivity. Nevertheless, measured severe gusts and wind damage reports continue as convection develops northeast along/just ahead of a surface cold front. The downstream airmass remains strongly unstable, and convection will persist along the length of the surface front from west-central WI into southeast MN and northern/western IA. The core of the low-level jet remains centered just east of ongoing storms, and stronger vertical shear tends to lag behind the surface boundary. Convection along the front in MN/WI has largely been unproductive overnight. While strong to severe gusts remain possible in the short term across IA, it is unclear if severe potential and a downstream watch will be needed into MN/WI. ..Leitman.. 08/09/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ARX...MPX...DMX...FSD...OAX... LAT...LON 42209589 43369401 44109232 44219166 44139112 43929084 43649094 42089297 41699356 41289449 41359542 41519595 41799610 42209589 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0748 AM CDT Sat Aug 09 2025 Valid 091300Z - 101200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR WESTERN KANSAS... ...SUMMARY... Multiple severe/damaging wind swaths should occur today centered on parts of Iowa, northwest Illinois, Wisconsin, and the Upper Peninsula of Michigan. Large to very large hail will be possible across parts of eastern Colorado and vicinity this afternoon and evening. ...Upper Great Lakes/Upper Midwest into the Missouri Valley... A small but intense bowing cluster has produced numerous severe gusts/damage reports (some 75+ mph) in a narrow corridor early this morning across south-central NE to western IA. This convection should continue east-northeastward across parts of central/northern IA through the rest of the morning, with an enhanced southwesterly low-level jet providing ample moist inflow. A very unstable airmass remains in place ahead of a cold front across this area, with MUCAPE around 3000-3500 J/kg. This large reservoir of buoyancy should continue to support a severe/damaging wind threat with this cluster into parts of central/northern IA for at least the next few hours. See Mesoscale Discussion 1911 for more details on the short-term severe threat associated with this bowing complex. Additional thunderstorms have developed along/near the cold front across a broader portion of the Upper Great Lakes and Upper Midwest. It still appears probable that multiple swaths of severe/damaging winds may occur through the afternoon and evening across parts of these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong to extreme instability should once again develop by this afternoon. While stronger mid-level flow and related deep-layer shear will tend to lag the cold front, they should still be sufficient to support organized convection, mainly linear clusters. Some adjustments have been made to the Slight Risk to account for the ongoing severe thunderstorms in IA, as well as additional activity forecast to occur through the afternoon and evening. The potential for additional robust convective development tonight across parts of the MO Valley remains unclear as a southerly low-level jet strengthens once again. Regardless, have maintained severe probabilities across southeast NE and vicinity for this possibility. ...Central/Southern High Plains... A cold front should become nearly stationary by this afternoon across the south-central High Plains. A favorable low-level, post-frontal regime for severe convection is expected to develop across eastern CO by late afternoon. The presence of steep mid-level lapse rates, moderate instability, and favorable deep-layer shear will likely support scattered supercells capable of large to very large hail, localized severe gusts, and possibly a tornado or two mainly this afternoon into the evening. Across the southern High Plains, high-based convection may again develop across parts of eastern NM into the OK/TX Panhandles. This activity could pose a isolated threat for severe gusts given a very well-mixed boundary layer. ..Gleason/Leitman.. 08/09/2025 Read more

MD 1910 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL IOWA
Mesoscale Discussion 1910 NWS Storm Prediction Center Norman OK 0531 AM CDT Sat Aug 09 2025 Areas affected...central Iowa Concerning...Severe potential...Watch possible Valid 091031Z - 091200Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms may increase in coverage ahead of a surface front through the morning hours. Damaging winds and isolated large hail will be possible. DISCUSSION...An intense hybrid supercell/small bow over southeast NE will continue to track east/northeast this morning ahead of a southeastward sagging surface cold front. If this convection is maintained, it will move into portions of western/central IA in the next couple of hours. Additional strong storms are also ongoing across parts of northwest IA and should gradually shift northeast toward north-central IA. A very moist airmass beneath steep midlevel lapse rates is supporting a corridor of strong instability ahead of the surface front. Effective shear magnitudes will increase through the morning, aiding in continued storm organization. While this convection will be moving into the region during a climatologically unfavorable time of day, widespread severe gusts have been noted with the ongoing storm across southeast NE over the past couple of hours, likely in part due to the large reservoir of instability in place. A new watch downstream from WW 579 may be needed in the next hour if current trends upstream continue. ..Leitman.. 08/09/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX... LAT...LON 41119483 41109528 41389561 41869576 42719509 43449422 43429348 42969311 42219311 41579326 41259398 41119483 MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...1.50-2.50 IN Read more

WW 0579 Status Updates
STATUS REPORT ON WW 579 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ESE BIE TO 30 ENE OLU TO 25 NW DNS. ..LEITMAN..08/09/25 ATTN...WFO...OAX...GID... STATUS REPORT FOR WS 579 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-091240- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-025-055-097-131-153-155-177-091240- NE . NEBRASKA COUNTIES INCLUDED ARE BURT CASS DOUGLAS JOHNSON OTOE SARPY SAUNDERS WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0579 Status Updates
STATUS REPORT ON WW 579 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ESE BIE TO 30 ENE OLU TO 25 NW DNS. ..LEITMAN..08/09/25 ATTN...WFO...OAX...GID... STATUS REPORT FOR WS 579 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-091240- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-025-055-097-131-153-155-177-091240- NE . NEBRASKA COUNTIES INCLUDED ARE BURT CASS DOUGLAS JOHNSON OTOE SARPY SAUNDERS WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more

WW 0579 Status Updates
STATUS REPORT ON WW 579 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 ESE BIE TO 30 ENE OLU TO 25 NW DNS. ..LEITMAN..08/09/25 ATTN...WFO...OAX...GID... STATUS REPORT FOR WS 579 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC085-129-133-155-165-091240- IA . IOWA COUNTIES INCLUDED ARE HARRISON MILLS MONONA POTTAWATTAMIE SHELBY NEC021-025-055-097-131-153-155-177-091240- NE . NEBRASKA COUNTIES INCLUDED ARE BURT CASS DOUGLAS JOHNSON OTOE SARPY SAUNDERS WASHINGTON THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES. Read more