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WW 0665 Status Updates
STATUS FOR WATCH 0665 HAS NOT BEEN ISSUED YET Read more

WW 665 TORNADO IA IL MO 272100Z - 280400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 665 NWS Storm Prediction Center Norman OK 400 PM CDT Fri Sep 27 2019 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Southeast Iowa West-central and northern Illinois Far northeast Missouri * Effective this Friday afternoon and evening from 400 PM until 1100 PM CDT. * Primary threats include... A few tornadoes and a couple intense tornadoes possible Scattered large hail and isolated very large hail events to 3 inches in diameter likely Scattered damaging winds and isolated significant gusts to 75 mph possible SUMMARY...Scattered severe thunderstorms are expected to develop from southeast Iowa into west-central and northern Illinois this evening, with supercells eventually consolidating into one or more clusters. The tornado watch area is approximately along and 65 statute miles north and south of a line from 60 miles west of Burlington IA to 25 miles south southeast of Marseilles IL. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and 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. && OTHER WATCH INFORMATION...CONTINUE...WW 664... AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 3 inches. Extreme turbulence and surface wind gusts to 65 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 25040. ...Grams Read more

WW 0664 Status Updates
STATUS FOR WATCH 0664 HAS NOT BEEN ISSUED YET Read more

WW 0664 Status Updates
STATUS FOR WATCH 0664 HAS NOT BEEN ISSUED YET Read more

WW 664 SEVERE TSTM IA IL 272050Z - 280400Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 664 NWS Storm Prediction Center Norman OK 350 PM CDT Fri Sep 27 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of South-central to east-central Iowa Northwest Illinois * Effective this Friday afternoon and evening from 350 PM until 1100 PM CDT. * Primary threats include... Scattered large hail and isolated very large hail events to 2 inches in diameter possible Isolated damaging wind gusts to 60 mph possible SUMMARY...Elevated thunderstorms should develop along the cool side of slow-moving cold front. Large hail will be the primary hazard. The severe thunderstorm watch area is approximately along and 65 statute miles north and south of a line from 30 miles southwest of Knoxville IA to 55 miles east southeast of Dubuque IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU4). 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. && AVIATION...A few severe thunderstorms with hail surface and aloft to 2 inches. Extreme turbulence and surface wind gusts to 50 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 25040. ...Grams Read more

5-Day Uncertainty Track last updated Fri, 27 Sep 2019 20:36:11 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2019 21:24:27 GMT

5-Day Uncertainty Track last updated Fri, 27 Sep 2019 20:36:06 GMT


Wind Speed Probabilities last updated Fri, 27 Sep 2019 21:31:20 GMT

Issued at 500 PM AST Fri Sep 27 2019 000 WTNT43 KNHC 272035 TCDAT3 Hurricane Lorenzo Discussion Number 21 NWS National Hurricane Center Miami FL AL132019 500 PM AST Fri Sep 27 2019 The satellite appearance of Lorenzo has degraded further since the last advisory, with only a hint of an eye still apparent in visible imagery and the cold cloud tops in the eyewall becoming very asymmetric in infrared imagery. A recent SSMI/S overpass shows that the southern portion of the eyewall has eroded, possibly due to shear or dry air intrusion. The microwave imagery also suggests an outer convective band is forming, but it is not yet well enough defined to call it an outer eyewall. Satellite intensity estimates have continued to decrease, and the initial intensity is lowered to 110 kt as a blend of the various estimates. The hurricane continues to have excellent outflow in the northern semicircle. The initial motion remains 330/12 kt. There is no change in the track forecast philosophy or the forecast confidence, as Lorenzo should turn northward and then northeastward during the next few days as it moves around the western edge of a mid-level ridge centered over the eastern Atlantic. Later in the forecast period, the cyclone is expected to accelerate northeastward in the mid-latitude westerlies ahead of a deep-layer trough approaching from the west. The track guidance for this advisory, while it remains tightly clustered in direction, is a little slower than the previous guidance. Based on this, the new forecast track is just a little slower than the previous forecast. Lorenzo will be passing over sea surface temperatures of 27-28C for the next 48-72 h. However, it will be in an environment of moderate vertical shear due to an upper-level trough not far to the west. The intensity guidance responds to this by showing gradual weakening during this time, and the new intensity forecast follows the trend of the guidance. There is a possibility of fluctuations in intensity caused by eyewall replacement cycles superimposed on this weakening trend. After 72 h, the hurricane should encounter stronger mid-latitude westerlies, move over cooler sea surface temperatures, and eventually merge with the above-mentioned deep-layer trough. As this occurs, Lorenzo is forecast to undergo extratropical transition, with this being complete by 120 h. Current indications from the global models are that Lorenzo will retain hurricane strength through the transition. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 20.3N 43.6W 110 KT 125 MPH 12H 28/0600Z 21.6N 44.1W 105 KT 120 MPH 24H 28/1800Z 23.3N 44.3W 100 KT 115 MPH 36H 29/0600Z 25.0N 44.0W 100 KT 115 MPH 48H 29/1800Z 26.6N 43.3W 100 KT 115 MPH 72H 30/1800Z 30.3N 41.1W 95 KT 110 MPH 96H 01/1800Z 35.5N 36.0W 90 KT 105 MPH 120H 02/1800Z 44.0N 26.5W 80 KT 90 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven

Issued at 500 PM AST Fri Sep 27 2019 702 WTNT42 KNHC 272035 TCDAT2 Remnants Of Karen Discussion Number 23 NWS National Hurricane Center Miami FL AL122019 500 PM AST Fri Sep 27 2019 Scatterometer data from a few hours ago indicated that Karen's circulation has opened up into a surface trough of low pressure. In addition, the associated convection has continued to lose organization. Therefore, the system is no longer a tropical cyclone, and this will be the final advisory. Maximum winds, based on the ASCAT pass, remain near 30 kt. Although an area of low pressure may persist for a few more days, the circulation should remain poorly organized, and the remnants are not expected to produce any significant convection. The surface trough is expected to move little during the next 24 hours, but it should then begin moving westward by 48 hours as high pressure builds over the western Atlantic. FORECAST POSITIONS AND MAX WINDS INIT 27/2100Z 29.3N 58.5W 30 KT 35 MPH...REMNANTS 12H 28/0600Z...DISSIPATED $$ Forecaster Berg

Issued at 500 PM AST Fri Sep 27 2019 000 WTNT33 KNHC 272034 TCPAT3 BULLETIN Hurricane Lorenzo Advisory Number 21 NWS National Hurricane Center Miami FL AL132019 500 PM AST Fri Sep 27 2019 ...LORENZO WEAKENS A LITTLE MORE BUT REMAINS VERY LARGE... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...20.3N 43.6W ABOUT 1575 MI...2535 KM SW OF THE AZORES MAXIMUM SUSTAINED WINDS...125 MPH...205 KM/H PRESENT MOVEMENT...NNW OR 330 DEGREES AT 12 MPH...19 KM/H MINIMUM CENTRAL PRESSURE...948 MB...28.00 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 500 PM AST (2100 UTC), the center of Hurricane Lorenzo was located near latitude 20.3 North, longitude 43.6 West. Lorenzo is moving toward the north-northwest near 12 mph (19 km/h), and this general motion is forecast to continue tonight. A turn toward the north is expected on Saturday, followed by a turn toward the north-northeast on Sunday. Maximum sustained winds are now near 125 mph (205 km/h) with higher gusts. Lorenzo is a category 3 hurricane on the Saffir-Simpson Hurricane Wind Scale. Gradual weakening is expected during the next few days. However, Lorenzo is expected to remain a powerful hurricane through the weekend. A combination of satellite wind data and reports from a NOAA Hurricane Hunter aircraft indicate that Lorenzo remains a large hurricane. Hurricane-force winds extend outward up to 45 miles (75 km) from the center and tropical-storm-force winds extend outward up to 265 miles (425 km). The estimated minimum central pressure is 948 mb (28.00 inches). HAZARDS AFFECTING LAND ---------------------- SURF: Swells generated by Lorenzo are affecting portions of the northeastern coast of South America and will affect portions of the Lesser Antilles beginning tonight through Saturday. 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 1100 PM AST. $$ Forecaster Beven

...LORENZO WEAKENS A LITTLE MORE BUT REMAINS VERY LARGE... As of 5:00 PM AST Fri Sep 27 the center of Lorenzo was located near 20.3, -43.6 with movement NNW at 12 mph. The minimum central pressure was 948 mb with maximum sustained winds of about 125 mph.

Issued at 2100 UTC FRI SEP 27 2019 000 FONT12 KNHC 272034 PWSAT2 REMNANTS OF KAREN WIND SPEED PROBABILITIES NUMBER 23 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122019 2100 UTC FRI SEP 27 2019 AT 2100Z THE REMNANTS OF KAREN WERE LOCATED NEAR LATITUDE 29.3 NORTH ...LONGITUDE 58.5 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 30 KTS...35 MPH...55 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 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 FRI 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 FRI 06Z SAT 18Z SAT 06Z SUN 18Z SUN 18Z MON 18Z TUE PERIODS TO TO TO TO TO TO TO 06Z SAT 18Z SAT 06Z SUN 18Z SUN 18Z MON 18Z TUE 18Z WED FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT ...THERE IS NO OFFICIAL FORECAST FOR THIS DATE/TIME... AND THEREFORE NO WIND SPEED PROBABILITIES CAN BE CALCULATED... $$ FORECASTER BERG

Issued at 2100 UTC FRI SEP 27 2019 000 WTNT23 KNHC 272034 TCMAT3 HURRICANE LORENZO FORECAST/ADVISORY NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132019 2100 UTC FRI SEP 27 2019 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. HURRICANE CENTER LOCATED NEAR 20.3N 43.6W AT 27/2100Z POSITION ACCURATE WITHIN 15 NM PRESENT MOVEMENT TOWARD THE NORTH-NORTHWEST OR 330 DEGREES AT 10 KT ESTIMATED MINIMUM CENTRAL PRESSURE 948 MB EYE DIAMETER 20 NM MAX SUSTAINED WINDS 110 KT WITH GUSTS TO 135 KT. 64 KT....... 40NE 30SE 25SW 40NW. 50 KT.......150NE 130SE 50SW 130NW. 34 KT.......230NE 220SE 120SW 200NW. 12 FT SEAS..330NE 330SE 360SW 330NW. 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 20.3N 43.6W AT 27/2100Z AT 27/1800Z CENTER WAS LOCATED NEAR 19.8N 43.3W FORECAST VALID 28/0600Z 21.6N 44.1W MAX WIND 105 KT...GUSTS 130 KT. 64 KT... 40NE 30SE 30SW 40NW. 50 KT...150NE 130SE 50SW 130NW. 34 KT...230NE 220SE 120SW 200NW. FORECAST VALID 28/1800Z 23.3N 44.3W MAX WIND 100 KT...GUSTS 120 KT. 64 KT... 50NE 40SE 30SW 50NW. 50 KT...140NE 120SE 60SW 90NW. 34 KT...220NE 200SE 120SW 160NW. FORECAST VALID 29/0600Z 25.0N 44.0W MAX WIND 100 KT...GUSTS 120 KT. 64 KT... 50NE 50SE 40SW 35NW. 50 KT...120NE 120SE 60SW 90NW. 34 KT...220NE 200SE 120SW 140NW. FORECAST VALID 29/1800Z 26.6N 43.3W MAX WIND 100 KT...GUSTS 120 KT. 64 KT... 50NE 50SE 40SW 40NW. 50 KT...120NE 110SE 70SW 90NW. 34 KT...220NE 200SE 120SW 140NW. FORECAST VALID 30/1800Z 30.3N 41.1W MAX WIND 95 KT...GUSTS 115 KT. 50 KT...110NE 110SE 90SW 90NW. 34 KT...230NE 230SE 160SW 160NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 01/1800Z 35.5N 36.0W MAX WIND 90 KT...GUSTS 110 KT. OUTLOOK VALID 02/1800Z 44.0N 26.5W...POST-TROP/EXTRATROP MAX WIND 80 KT...GUSTS 100 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 20.3N 43.6W NEXT ADVISORY AT 28/0300Z $$ FORECASTER BEVEN

Issued at 2100 UTC FRI SEP 27 2019 000 WTNT22 KNHC 272034 TCMAT2 REMNANTS OF KAREN FORECAST/ADVISORY NUMBER 23 NWS NATIONAL HURRICANE CENTER MIAMI FL AL122019 2100 UTC FRI SEP 27 2019 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. REMNANTS OF CENTER LOCATED NEAR 29.3N 58.5W AT 27/2100Z POSITION ACCURATE WITHIN 40 NM PRESENT MOVEMENT TOWARD THE NORTHEAST OR 45 DEGREES AT 5 KT ESTIMATED MINIMUM CENTRAL PRESSURE 1007 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 29.3N 58.5W AT 27/2100Z AT 27/1800Z CENTER WAS LOCATED NEAR 29.1N 58.7W FORECAST VALID 28/0600Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 29.3N 58.5W THIS IS THE LAST FORECAST/ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER ON THIS SYSTEM. ADDITIONAL INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. $$ FORECASTER BERG

Issued at 500 PM AST Fri Sep 27 2019 000 WTNT32 KNHC 272034 TCPAT2 BULLETIN Remnants Of Karen Advisory Number 23 NWS National Hurricane Center Miami FL AL122019 500 PM AST Fri Sep 27 2019 ...KAREN DEGENERATES INTO A SURFACE TROUGH... ...THIS IS THE LAST ADVISORY... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...29.3N 58.5W ABOUT 425 MI...685 KM ESE OF BERMUDA MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NE OR 45 DEGREES AT 6 MPH...9 KM/H MINIMUM CENTRAL PRESSURE...1007 MB...29.74 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 500 PM AST (2100 UTC), the remnants of Karen were located near latitude 29.3 North, longitude 58.5 West. The remnants are moving toward the northeast near 6 mph (9 km/h) but should stall and then begin moving westward over the weekend. Maximum sustained winds are near 35 mph (55 km/h) with higher gusts. Winds associated with the remnants are expected to gradually decrease during the next several days. The estimated minimum central pressure is 1007 mb (29.74 inches). HAZARDS AFFECTING LAND ---------------------- None. NEXT ADVISORY ------------- This is the last public advisory issued by the National Hurricane Center on this system. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php $$ Forecaster Berg

...KAREN DEGENERATES INTO A SURFACE TROUGH... ...THIS IS THE LAST ADVISORY... As of 5:00 PM AST Fri Sep 27 the center of Karen was located near 29.3, -58.5 with movement NE at 6 mph. The minimum central pressure was 1007 mb with maximum sustained winds of about 35 mph.

MD 2026 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR PARTS OF SOUTHEASTERN IOWA...NORTHEASTERN MISSOURI...NORTHWESTERN AND CENTRAL ILLINOIS
Mesoscale Discussion 2026 NWS Storm Prediction Center Norman OK 0301 PM CDT Fri Sep 27 2019 Areas affected...Parts of southeastern Iowa...northeastern Missouri...northwestern and central Illinois Concerning...Severe potential...Watch likely Valid 272001Z - 272200Z Probability of Watch Issuance...80 percent SUMMARY...Potential for isolated to widely scattered discrete supercell development could increase as early as 5-7 PM CDT. A severe weather watch will probably be needed at some point, although timing still remains a little unclear. DISCUSSION...Although latest model output, including the Rapid Refresh, suggest that at least some weakening of the pre-frontal low-level jet is underway, flow around 850 mb appears to remain on the order of 40-50 kt along an axis south of Kansas City into northwest/west central Illinois. This is maintaining a zone of enhanced low-level warm advection and associated convective development, roughly along the Interstate 74 corridor of Illinois. On the southwestern flank of this activity, differential surface heating is contributing to a sharpening baroclinic zone, which may only very slowly begin to shift northeastward in advance of a low-amplitude mid-level wave emerging from the central Plains. Along and west of the boundary, a generally capped moist boundary layer now appears characterized by moderately large CAPE in excess of 2000 J/kg. Increasing inflow of this air could support intensification of ongoing convection rooted above the stable near surface air across central Illinois during the next few hours. Perhaps of greater concern, attempts at new thunderstorm development appear underway in closer proximity to the surface boundary, northeast of Quincy, with similar additional discrete storm development possible just ahead of a southward advancing cold front, from near the eastern Iowa/Missouri border area through adjacent portions of southeast Iowa and northwest Illinois by 22-00Z. Aided by large-scale forcing for ascent (and weakening of inhibition) associated with the approaching mid-level wave, and coinciding strengthening of west-southwesterly flow to 50-60+ kt in the 700-500 mb layer, the environment is expected to become increasingly conducive to discrete supercell development. It appears that this could pose the risk for a couple of tornadoes, in addition to large hail. ..Kerr/Grams.. 09/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LOT...ILX...LSX...DVN...DMX...EAX... LAT...LON 41679187 41999045 41228840 39838910 40059112 40299328 41209322 41679187 Read more

No watches are valid as of Fri Sep 27 20:03:09 UTC 2019.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Fri Sep 27 2019 Valid 272000Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST SOUTHEAST IOWA...NORTHEAST MISSOURI INTO NORTHERN ILLINOIS... ...SUMMARY... Scattered to numerous severe thunderstorms are expected late this afternoon into the evening from northern Illinois, southern Iowa, northern Missouri and eastern Kansas. The primary threats are large hail and damaging wind, but a few tornadoes remain possible. ...Midwest through central Kansas... Destabilization is occurring from KS, northern MO into southern IA in wake of a large MCS ongoing from northern IL into lower MI. As of mid-afternoon, objective analysis indicates a corridor of 2000-2500 J/kg MLCAPE from KS into northern MO and southern IA, but a warm elevated mixed layer has contributed to a cap in most of the warm sector. Water Vapor and objective analysis data show a weak, low-amplitude shortwave trough moving through the central Plains. Deeper forcing for ascent attending this feature will interact with the frontal zone, and thunderstorms should develop along and north of the front later this afternoon and evening from KS into northern MO and southern IA and spread east into northern IL. Effective-bulk shear from 35-45 kt within the frontal zone should support a few supercells with large hail as the initial storm mode. Many of these storms will be elevated above the stable surface layer, but any storms developing along the leading edge of the front will be near surface based. Tendency has been for low-level winds to veer to southwesterly in pre-frontal warm sector, reducing the size of low-level hodographs, but 0-1 km storm relative helicity from 150-200 m2/s2 remains sufficient for low-level mesocyclones with any surface-based supercells. Largest low-level hodographs exist on the cool side of an outflow boundary over northern IL where winds remain backed to southeasterly. Some surface-layer recovery is expected, mainly along the western periphery of this boundary, supporting the best isolated tornado threat near and just east of the southeast IA / IL border. Otherwise, tendency should be for storms to eventually congeal into clusters/lines in post-frontal zone during the evening. Reference swomcd 2026 for more information. ..Dial.. 09/27/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Sep 27 2019/ ...KS to Lower MI... Elevated convection is ongoing within a low-level warm advection regime across the Mid-MO Valley and northern IL. Robust boundary-layer heating is underway in the wake of this morning activity beneath an elevated mixed layer that is attempting to advect northeast from the central Great Plains/Lower MO Valley. In conjunction with surface dew points increasing into the upper 60s to lower 70s surface dew points, a strongly unstable air mass with MLCAPE of 2500-3500 J/kg should develop ahead of a southwest-northeast cold front from eastern KS to the IA/IL/MO border area. Despite near-neutral mid-level height tendency, guidance is fairly consistent with the presence of a mid-level speed max developing across northeast KS this afternoon and reaching the IA/IL border area this evening. While the bulk of initial convective development may be atop a more stable boundary-layer from central IA to southern WI, sufficient convergence should exist for storm development along the front and into the warm sector from its intersection with the differential heating boundary in northern IL to the dryline intersection in south-central KS. The greatest convective coverage should reside near the IA/IL/MO border region with more scattered coverage back into eastern KS. Low to deep-layer wind profiles will favor potential for several supercells during the early evening which will probably consolidate into multiple organized clusters through late evening. Large hail will be the most probable hazard with scattered severe wind gusts expected as well. Given rich boundary-layer moisture and an enlarged low-level hodograph, certainly a tornado risk will exist with any supercells just ahead of the front. 12Z HREF guidance and related CAMs are indicative of higher-end tornado coverage. However, with cyclolysis expected, the overall synoptic pattern should be a limiting factor. Still, given the potential for at least a few tornadoes, will double-upgrade from less than 2 percent to a 5 percent area with this outlook. ...Southeast NM and west TX... A low-amplitude shortwave trough near the AZ/Sonora border should approach the TX Panhandle. Scattered storms should develop this evening into the overnight. Modest buoyancy, the bulk of which should remain below the strong speed shear from the mid to upper levels, will probably marginalize the overall severe hail and wind risk. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Fri Sep 27 2019 Valid 272000Z - 281200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM NORTHEAST SOUTHEAST IOWA...NORTHEAST MISSOURI INTO NORTHERN ILLINOIS... ...SUMMARY... Scattered to numerous severe thunderstorms are expected late this afternoon into the evening from northern Illinois, southern Iowa, northern Missouri and eastern Kansas. The primary threats are large hail and damaging wind, but a few tornadoes remain possible. ...Midwest through central Kansas... Destabilization is occurring from KS, northern MO into southern IA in wake of a large MCS ongoing from northern IL into lower MI. As of mid-afternoon, objective analysis indicates a corridor of 2000-2500 J/kg MLCAPE from KS into northern MO and southern IA, but a warm elevated mixed layer has contributed to a cap in most of the warm sector. Water Vapor and objective analysis data show a weak, low-amplitude shortwave trough moving through the central Plains. Deeper forcing for ascent attending this feature will interact with the frontal zone, and thunderstorms should develop along and north of the front later this afternoon and evening from KS into northern MO and southern IA and spread east into northern IL. Effective-bulk shear from 35-45 kt within the frontal zone should support a few supercells with large hail as the initial storm mode. Many of these storms will be elevated above the stable surface layer, but any storms developing along the leading edge of the front will be near surface based. Tendency has been for low-level winds to veer to southwesterly in pre-frontal warm sector, reducing the size of low-level hodographs, but 0-1 km storm relative helicity from 150-200 m2/s2 remains sufficient for low-level mesocyclones with any surface-based supercells. Largest low-level hodographs exist on the cool side of an outflow boundary over northern IL where winds remain backed to southeasterly. Some surface-layer recovery is expected, mainly along the western periphery of this boundary, supporting the best isolated tornado threat near and just east of the southeast IA / IL border. Otherwise, tendency should be for storms to eventually congeal into clusters/lines in post-frontal zone during the evening. Reference swomcd 2026 for more information. ..Dial.. 09/27/2019 .PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Sep 27 2019/ ...KS to Lower MI... Elevated convection is ongoing within a low-level warm advection regime across the Mid-MO Valley and northern IL. Robust boundary-layer heating is underway in the wake of this morning activity beneath an elevated mixed layer that is attempting to advect northeast from the central Great Plains/Lower MO Valley. In conjunction with surface dew points increasing into the upper 60s to lower 70s surface dew points, a strongly unstable air mass with MLCAPE of 2500-3500 J/kg should develop ahead of a southwest-northeast cold front from eastern KS to the IA/IL/MO border area. Despite near-neutral mid-level height tendency, guidance is fairly consistent with the presence of a mid-level speed max developing across northeast KS this afternoon and reaching the IA/IL border area this evening. While the bulk of initial convective development may be atop a more stable boundary-layer from central IA to southern WI, sufficient convergence should exist for storm development along the front and into the warm sector from its intersection with the differential heating boundary in northern IL to the dryline intersection in south-central KS. The greatest convective coverage should reside near the IA/IL/MO border region with more scattered coverage back into eastern KS. Low to deep-layer wind profiles will favor potential for several supercells during the early evening which will probably consolidate into multiple organized clusters through late evening. Large hail will be the most probable hazard with scattered severe wind gusts expected as well. Given rich boundary-layer moisture and an enlarged low-level hodograph, certainly a tornado risk will exist with any supercells just ahead of the front. 12Z HREF guidance and related CAMs are indicative of higher-end tornado coverage. However, with cyclolysis expected, the overall synoptic pattern should be a limiting factor. Still, given the potential for at least a few tornadoes, will double-upgrade from less than 2 percent to a 5 percent area with this outlook. ...Southeast NM and west TX... A low-amplitude shortwave trough near the AZ/Sonora border should approach the TX Panhandle. Scattered storms should develop this evening into the overnight. Modest buoyancy, the bulk of which should remain below the strong speed shear from the mid to upper levels, will probably marginalize the overall severe hail and wind risk. Read more