Severe Storms

No watches are valid as of Thu Feb 27 13:08:01 UTC 2020.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0621 AM CST Thu Feb 27 2020 Valid 271300Z - 281200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk of thunderstorms appears negligible across the U.S. through tonight. ...Synopsis... The upper-air pattern east of the Rockies will be dominated by a large area of cyclonic flow. This will be related to the congealing of several shortwaves into a dominant synoptic-scale cyclone centered over the southwestern QC region by late tonight. Upstream ridging will shift eastward from the Pacific Coast across the northern Rockies and Great Basin. In the low levels, a continental/ polar air mass in the central and eastern CONUS -- with offshore flow over the Gulf and Atlantic Coasts -- and dry/stable conditions near the western mid/upper ridge, will preclude thunderstorm potential this period. ..Edwards.. 02/27/2020 Read more

MD 0133 CONCERNING HEAVY SNOW FOR NORTHERN NEW HAMPSHIRE THROUGH WESTERN MAINE
Mesoscale Discussion 0133 NWS Storm Prediction Center Norman OK 0518 AM CST Thu Feb 27 2020 Areas affected...northern New Hampshire through western Maine Concerning...Heavy snow Valid 271118Z - 271615Z SUMMARY...Periods of moderate to heavy snow expected to expand northward from northern NH through western Maine this morning with rates locally exceeding 1 inch per hour at times. DISCUSSION...This morning water vapor imagery shows a negative-tilt shortwave trough across PA and NY moving northeast toward New England. The attendant surface low was situated over southeast NY with a warm front extending eastward off the coast of southern New England. A 50-60 kt southerly low-level jet coupled within the exit region of an upper jet streak is resulting in a broad corridor of strong and deep isentropic ascent north of the warm front. The resulting broad precipitation shield is rapidly expanding northeastward. Despite the very strong warm advection regime as evidenced by the strong veering and large hodographs within the lowest 3 km, both dynamic cooling associated with strong vertical motion as well as wet wet-bulb cooling should result in temperature profiles near and below freezing across western Maine. Some rain or sleet could mix with the snow at the onset, before profiles cool sufficiently to support a heavy wet snow. Strong and deep ascent will extend through layers supportive of dendritic growth for several hours before the mid-level dry slot arrives from the south toward mid day. ..Dial.. 02/27/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CAR...GYX... LAT...LON 45817036 46866966 46736889 45906850 45156941 44727024 44387090 44167137 44747143 45017124 45227088 45817036 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0238 PM CDT Tue Oct 01 2019 Valid 021200Z - 031200Z Locally critical surface wind/RH conditions still appear possible across portions of central Colorado within the elevated delineation, with temperatures still appearing to be on the cool side. The cooler temperatures, and 20+ mph sustained winds being confined to terrain favoring areas precludes a critical delineation at this time. Similarly, locally critical conditions in the mountains and foothills of southern California still appear possible both early Wednesday morning, and then again late Wednesday evening. Both the localized and brief nature of the critical conditions continue to preclude a critical area addition here as well. Relatively dry, breezy conditions are also possible across parts of the lower Ohio Valley into the Mid-Atlantic late Wednesday afternoon in advance of an approaching cold front. While wind/RH are expected to remain generally below elevated criteria in these regions, abnormally high surface temperatures (well over 90F) and drying fuels associated with a mild to locally moderate short-term drought may compensate to support localized grass-fire potential. Otherwise, the previous forecast remains largely on track. Please see the previous forecast below for more details. ..Squitieri.. 10/01/2019 .PREV DISCUSSION... /ISSUED 1222 AM CDT Tue Oct 01 2019/ ...Synopsis... The western U.S. mid-level trough will continue to evolve into an open wave while migrating eastward toward the northern High Plains. Mid-level flow across dry areas of the central Rockies will remain strong however even as the mid-level jet migrates away from the region. Mid/upper ridging will remain in place across the southeastern U.S. throughout the forecast period. Meanwhile at the surface, high pressure will build into the Great Basin and setup a modest offshore gradient across coastal ranges of southern California. A front will make southward progress across the central Plains as well, though specific timing of this phenomenon is a bit uncertain. ...Colorado... Vertical mixing processes beneath stronger flow aloft will encourage gusty westerly surface winds during peak heating hours even though surface temperatures will be somewhat cooler than in prior days. 15 mph westerly winds will become common, though this flow will be stronger in terrain-favored areas and may exceed 20 mph at times. Meanwhile, critically low RH will develop by afternoon, and a few locales may fall below 10%. Given dry fuels across the area, elevated to locally critical fire weather conditions are likely and an elevated delineation has been introduced for this outlook. ...Southern California... An offshore surface pressure gradient will develop as high pressure builds into the Great Basin. Easterly/northeasterly surface flow will develop and exceed 20 mph at times in terrain-favored areas. These conditions will occur amidst 20-25% RH values at times, although winds should weaken some during the day before strengthening again late D2/Wednesday. These conditions are consistent with elevated fire weather thresholds and an attendant delineation has been introduced. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Oct 1 19:40:02 UTC 2019.

MD 2047 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR FAR NORTHEAST KS...FAR SOUTHEAST NE...FAR NORTHWEST MO...SOUTHWEST IA
Mesoscale Discussion 2047 NWS Storm Prediction Center Norman OK 0208 PM CDT Tue Oct 01 2019 Areas affected...far northeast KS...far southeast NE...far northwest MO...southwest IA Concerning...Severe potential...Watch possible Valid 011908Z - 012015Z Probability of Watch Issuance...60 percent SUMMARY...A couple of supercells may develop this afternoon into the early evening. The risk for a tornado and isolated damaging gusts may maximize during the 4-7pm period. DISCUSSION...Radar mosaic shows a couple of storms developing in the open warm sector ahead of a stalled front draped across central KS northeast into parts of southeast NE and western IA. A supercell has recently formed in Pawnee County, NE. Surface temperatures have warmed into the lower-middle 80s with lower 70s dewpoints. Objective analysis is indicating MLCAPE is around 1500-2000 J/kg. Time-lagged RAP and 12z NAM forecast soundings are showing hodographs increasing through the afternoon. Although hodograph size is not particularly large as of 2pm (when comparing area 88D VAD to their forecast hodograph counterparts), a narrow zone from northeast KS into southwest IA is forecast to undergo marked improvement in hodograph shape/size through 5-6pm. As such, a risk for a tornado and isolated damaging gusts appears to be increasing. ..Smith/Hart.. 10/01/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...EAX...OAX...TOP... LAT...LON 40009731 41329510 41499400 41059392 39569657 39609718 40009731 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1206 PM CDT Tue Oct 01 2019 Valid 021200Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND SOUTHERN PLAINS TO THE MID-MISSISSIPPI VALLEY WEDNESDAY AFTERNOON AND EVENING... ...SUMMARY... Isolated severe storms may occur Wednesday across parts of the southern/central Plains and mid Mississippi Valley. ...Southern/Central Plains to the Mid-MS Valley... A mid/upper level shortwave trough will eject east/northeast from the central Rockies to the Upper Midwest on Wednesday. Associated strong deep-layer southwesterly flow will stretch from northeast NM toward the Lake Michigan vicinity while a surface cold front extends from a weak low in the vicinity of the OK/TX Panhandles northeast to northern IL Wednesday morning. The cold front will slowly sag south/southeast through 00z/Thu with a very moist airmass (dew points mid 60s to low 70s) residing ahead of the front. Strong heating of the warm sector will result in a narrow corridor of weak to moderate instability by afternoon. The strongest shear will likely remain north of the differential heating zone, but effective shear should be sufficient for marginal supercell structures and semi-organized storm clusters. Strong gusts aided by steepening low level lapse rates and anomalously high PW values will be the main concern with storms during the afternoon and evening. After 00z, the cold front will surge southward more quickly and the main mid/upper level wave ejects across the northern Plains and convection may tend to become undercut by the front, limiting severe wind potential. While instability and shear will support sustained updrafts, poor midlevel lapse rates should limit hail threat, though some small stones could be possible in the strongest storms through the evening hours. ...Mid-Atlantic Vicinity... A weak midlevel shortwave impulse will migrate across the region during the morning and afternoon as the eastern extension of a surface cold front extends west-to-east from near Lake Erie through southern NY and MA. The front will sag southward through the afternoon and isolated thunderstorms are expected to develop. While mid to upper 60s dewpoints are expected, surface heating will be rather modest and only weak instability is expected. Furthermore, forecast soundings suggest midlevel warming will increase as a mid/upper level ridge building eastward behind the shortwave impulse. This will act to limit updraft longevity/intensity and severe potential appears low at this time. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Leitman.. 10/01/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Tue Oct 01 2019 Valid 011700Z - 021200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN UTAH INTO WESTERN COLORADO... The forecast remains on track, with no changes made. Please see the previous discussion below for more details. ..Squitieri.. 10/01/2019 .PREV DISCUSSION... /ISSUED 1227 AM CDT Tue Oct 01 2019/ ...Synopsis... Over the course of the forecast period, the western U.S. longwave trough will begin to eject toward the northern and central Rockies. As this occurs, a belt of enhanced mid-level flow will persist across portions of the central Rockies through peak heating. Meanwhile, a downstream ridge will persist across the Deep South and Tennessee Valley, which should keep that region abnormally warm and dry. At the surface, a weak low will meander across the Great Basin. A second lee low will linger across eastern Colorado and western Kansas during the afternoon near a slowly southward-moving cold front across that area. ...Northern Arizona, eastern Utah, much of Colorado, and northwestern New Mexico... A dry low-level airmass will persist across the Great Basin and vicinity throughout the forecast period. During the afternoon and early evening, insolation/surface heating within this dry airmass will result in downward transport of mid-level flow and ultimately 20-25 mph surface winds with higher gusts especially in terrain-favored areas. Minimum RH values should also fall below 10% for a few hours during peak heating. Given the increased confidence in presence of critical conditions, a critical upgrade has been made for this outlook across eastern Utah and western Colorado. Locally critical conditions are expected to occur outside of the critical delineation - especially across central Colorado west of Pueblo. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1114 AM CDT Tue Oct 01 2019 Valid 011630Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL KANSAS NORTHEASTWARD INTO LOWER MICHIGAN... ...SUMMARY... Isolated strong to severe storms are expected from late afternoon into the mid evening from parts of the Great Plains into the Mid Missouri Valley and Great Lakes. ...WI to MI... A large upper ridge is centered over the central/southern MS Valley today, with relatively strong midlevel winds extending from west TX into IA/WI and eastward into MI/NY/VT. This axis is where the surface baroclinic zone lies, and will be the focus for organized thunderstorm development today and tonight. Once cluster of storms is currently over WI and Lower MI. Heating is occurring along the southern flank of this activity, where sufficient destabilization will result in surface-based storms by mid-afternoon. Forecast soundings show sufficient westerly flow aloft for a risk of a few damaging wind gusts in the strongest cells. Please refer to MCD #2046 for more details. ...TX to IA... A large but weakening MCS over the TX Panhandle will likely track into northwest OK and central KS this afternoon, where MLCAPE values around 1000 J/kg will develop. Midlevel lapse rates are forecast to be weak, limiting updraft intensity and hail threat. However, strong winds aloft and sufficient vertical shear will pose a risk of bowing/rotating cells capable of damaging winds and a tornado or two from central KS into parts of northwest MO and IA. ...NY/VT... Strong heating is occurring today over parts of southern Ontario, where sufficient CAPE will result in scattered afternoon thunderstorms. These storms will track eastward into parts of northern NY and VT. Forecast soundings show strong winds aloft and perhaps enough thermodynamic support for a few strong/severe storms capable of damaging wind gusts. However, broken cloud cover and dewpoints only in the 50s to lower 60s in much of the region will likely limit the extent of the threat today. ..Hart/Kerr.. 10/01/2019 Read more

No Mesoscale Discussions are in effect as of Tue Oct 1 06:03:01 UTC 2019.

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Oct 01 2019 Valid 021200Z - 031200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN/CENTRAL PLAINS AND MID MISSISSIPPI VALLEY... ...SUMMARY... Isolated severe storms may occur Wednesday across parts of the southern/central Plains and mid Mississippi Valley. ...Southern/Central Plains to the Mid Mississippi Valley... An upper trough/low initially over the Rockies Wednesday morning will eject eastward across the northern/central Plains through the period. At the surface, a weak low is forecast to develop northeastward along a nearly stationary front from the central High Plains to the mid MS Valley by Wednesday evening. The front should begin accelerating southward across the southern Plains Wednesday night into early Thursday morning. A moist low-level airmass is expected to persist along/south of the surface boundary across much of the southern/central Plains and mid MS Valley. As diurnal heating occurs across this region, weak to locally moderate instability should develop. Although stronger mid-level southwesterly flow may remain mostly displaced to the north of the areas with strongest instability, there will probably be around 30-40 kt of effective bulk shear present across the warm sector. A relatively narrow corridor of severe potential is evident Wednesday afternoon and evening from parts of northern OK into eastern KS, MO, and far western IL. A mixed mode of marginal supercells and small clusters may occur, with generally southwesterly flow through the troposphere limiting hodograph curvature. Strong to locally damaging winds should be the main threat, although marginally severe hail cannot be ruled out. ...Mid-Atlantic... A subtle shortwave trough embedded within enhanced westerly flow at mid/upper levels is forecast to move eastward from the Great Lakes and across the Mid-Atlantic on Wednesday. A surface front is also expected to be oriented generally east-west across this region. Instability will likely remain meager along/south of the front owing to quite poor mid-level lapse rates. This should tend to limit the updraft strength of any storms that can form Wednesday afternoon along the boundary, even through shear will be strong. Severe probabilities have not been included across this region owing to the lack of sufficient instability in most model guidance. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Gleason.. 10/01/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1232 AM CDT Tue Oct 01 2019 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL PLAINS TO THE SOUTHERN GREAT LAKES... ...SUMMARY... Isolated strong to severe storms are expected later today from parts of the central Plains into the lower Great Lakes region. ...Discussion... Dominant upper high will hold across the Mid-South early this week ensuring a very moist trajectory extending around the periphery of this feature from the southern Rockies - central Plains - southern Great Lakes. One significant short-wave trough should top the ridge over southern Canada then dig southeast toward northern New England late in the period. In response to this feature, a surface low will track southeast across QC allowing a surface front to surge south of the international border later this evening. Prior to frontal passage, a few strong/severe thunderstorms should develop over southern ON then spread toward upstate NY with gusty winds being the primary risk with this convection. Farther west across the Plains into the southern Great Lakes, an embedded short-wave trough will lift northeast across the southern High Plains into central KS by early afternoon. This feature should encourage a weak wave to form along a pronounced front over central KS then track northeast into northwest IL by sunrise Wednesday. Models are in general agreement that a narrow band of extensive frontal convection will evolve ahead of the short wave, likely developing fairly early in the afternoon. Wind profiles are forecast to increase along this corridor such that shear will be more than adequate for sustaining organized rotating updrafts. However, considerable amount of convection may disrupt discrete cells, and thunderstorm clusters and possible line segments may be more common. CAMs support this scenario as well. Given the expected buoyancy along the front, have opted to increase severe probs to account for a higher threat for damaging winds with these high-PW thunderstorms. ..Darrow/Cook.. 10/01/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1227 AM CDT Tue Oct 01 2019 Valid 011200Z - 021200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN UTAH AND WESTERN COLORADO... ...Synopsis... Over the course of the forecast period, the western U.S. longwave trough will begin to eject toward the northern and central Rockies. As this occurs, a belt of enhanced mid-level flow will persist across portions of the central Rockies through peak heating. Meanwhile, a downstream ridge will persist across the Deep South and Tennessee Valley, which should keep that region abnormally warm and dry. At the surface, a weak low will meander across the Great Basin. A second lee low will linger across eastern Colorado and western Kansas during the afternoon near a slowly southward-moving cold front across that area. ...Northern Arizona, eastern Utah, much of Colorado, and northwestern New Mexico... A dry low-level airmass will persist across the Great Basin and vicinity throughout the forecast period. During the afternoon and early evening, insolation/surface heating within this dry airmass will result in downward transport of mid-level flow and ultimately 20-25 mph surface winds with higher gusts especially in terrain-favored areas. Minimum RH values should also fall below 10% for a few hours during peak heating. Given the increased confidence in presence of critical conditions, a critical upgrade has been made for this outlook across eastern Utah and western Colorado. Locally critical conditions are expected to occur outside of the critical delineation - especially across central Colorado west of Pueblo. ..Cook.. 10/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1222 AM CDT Tue Oct 01 2019 Valid 021200Z - 031200Z ...Synopsis... The western U.S. mid-level trough will continue to evolve into an open wave while migrating eastward toward the northern High Plains. Mid-level flow across dry areas of the central Rockies will remain strong however even as the mid-level jet migrates away from the region. Mid/upper ridging will remain in place across the southeastern U.S. throughout the forecast period. Meanwhile at the surface, high pressure will build into the Great Basin and setup a modest offshore gradient across coastal ranges of southern California. A front will make southward progress across the central Plains as well, though specific timing of this phenomenon is a bit uncertain. ...Colorado... Vertical mixing processes beneath stronger flow aloft will encourage gusty westerly surface winds during peak heating hours even though surface temperatures will be somewhat cooler than in prior days. 15 mph westerly winds will become common, though this flow will be stronger in terrain-favored areas and may exceed 20 mph at times. Meanwhile, critically low RH will develop by afternoon, and a few locales may fall below 10%. Given dry fuels across the area, elevated to locally critical fire weather conditions are likely and an elevated delineation has been introduced for this outlook. ...Southern California... An offshore surface pressure gradient will develop as high pressure builds into the Great Basin. Easterly/northeasterly surface flow will develop and exceed 20 mph at times in terrain-favored areas. These conditions will occur amidst 20-25% RH values at times, although winds should weaken some during the day before strengthening again late D2/Wednesday. These conditions are consistent with elevated fire weather thresholds and an attendant delineation has been introduced. ..Cook.. 10/01/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0669 Status Updates
STATUS REPORT ON WW 669 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 SE FRM TO 20 ENE MSP TO 65 NE MSP TO 50 S DLH. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2045 ..DIAL..10/01/19 ATTN...WFO...MPX...DLH... STATUS REPORT FOR WS 669 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC037-043-047-049-131-147-161-010240- MN . MINNESOTA COUNTIES INCLUDED ARE DAKOTA FARIBAULT FREEBORN GOODHUE RICE STEELE WASECA WIC005-013-033-091-093-095-109-129-010240- WI . WISCONSIN COUNTIES INCLUDED ARE BARRON BURNETT DUNN PEPIN PIERCE POLK ST. CROIX WASHBURN 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 Read more

WW 0669 Status Updates
STATUS REPORT ON WW 669 SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 15 SE FRM TO 20 ENE MSP TO 65 NE MSP TO 50 S DLH. FOR ADDITIONAL INFORMATION SEE MESOSCALE DISCUSSION 2045 ..DIAL..10/01/19 ATTN...WFO...MPX...DLH... STATUS REPORT FOR WS 669 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS MNC037-043-047-049-131-147-161-010240- MN . MINNESOTA COUNTIES INCLUDED ARE DAKOTA FARIBAULT FREEBORN GOODHUE RICE STEELE WASECA WIC005-013-033-091-093-095-109-129-010240- WI . WISCONSIN COUNTIES INCLUDED ARE BARRON BURNETT DUNN PEPIN PIERCE POLK ST. CROIX WASHBURN 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 Read more

WW 669 SEVERE TSTM MN WI 302335Z - 010500Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 669 NWS Storm Prediction Center Norman OK 635 PM CDT Mon Sep 30 2019 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Eastern and southern Minnesota Northwest Wisconsin * Effective this Monday night from 635 PM until Midnight CDT. * Primary threats include... Isolated damaging wind gusts to 70 mph possible Isolated large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Storms should continue to intensify initially across eastern/southern Minnesota early this evening. While there is some uncertainty regarding the overall coverage/likelihood of severe storms this evening, the environment supports the possibility of isolated large hail, locally damaging winds and perhaps a tornado. The severe thunderstorm watch area is approximately along and 50 statute miles east and west of a line from 95 miles north northeast of Minneapolis MN to 25 miles east southeast of Fairmont MN. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU9). 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 1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 24035. ...Guyer Read more

MD 2045 CONCERNING SEVERE THUNDERSTORM WATCH 669... FOR SOUTHEAST MINNESOTA THROUGH NORTHWEST WISCONSIN
Mesoscale Discussion 2045 NWS Storm Prediction Center Norman OK 0833 PM CDT Mon Sep 30 2019 Areas affected...southeast Minnesota through northwest Wisconsin Concerning...Severe Thunderstorm Watch 669... Valid 010133Z - 010230Z The severe weather threat for Severe Thunderstorm Watch 669 continues. SUMMARY...Storms will continue to pose a modest threat for locally strong wind gusts and hail through 03Z from southeast Minnesota through northwest Wisconsin. Storms will approach the eastern bound of WW 669 between 02-03Z, but given convective trends and the somewhat marginal nature of the remaining threat, a downstream WW is not anticipated. DISCUSSION...A broken band of storms persists from northwest WI into southeast MN moving east at near 30 kt. Some marginal supercell structures continue to be observed, but overall intensity of the storms have remained below severe levels so far. Despite presence of moderate instability with 2000-2500 J/kg MLCAPE, the 00Z RAOB from Minneapolis confirms presence of a warm layer between 700 and 500 mb resulting in a top-heavy CAPE that is limiting low-level updraft accelerations. This RAOB also sampled the dry air in the 700-500 mb layer which is also likely mitigating mid-level updraft strength through the effect of dry air entrainment. Storms remain embedded within a favorable kinematic environment with sizeable low-level hodographs and 50 kt effective bulk shear, which will continue to support occasional supercell structures. But given a stabilizing boundary layer along with the previously mentioned limitations in the thermodynamic environment, the remaining threat will probably begin to wane by 03-04Z. ..Dial.. 10/01/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DLH...ARX...MPX... LAT...LON 43719402 44659323 45729262 46039232 46109179 45859119 44979127 44019233 43529354 43719402 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 PM CDT Mon Sep 30 2019 Valid 010100Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER MS VALLEY AND CENTRAL PLAINS... ...SUMMARY... Isolated large hail and damaging gusts remain possible this evening across parts of the upper Mississippi Valley. A greater risk for hail is expected across portions of Nebraska. ...01z Update... Scattered thunderstorms have developed along pronounced front from the Arrowhead of MN - MSP - Martin County MN, near the IA border. This activity is struggling to attain severe levels, much in line with earlier CAMs regarding updraft strength/intensity. Even so, 00z sounding from MPX exhibits substantial SBCAPE with 50kt+ sfc-6km shear. Environmental parameters remain favorable for severe with this frontal activity; however, convective trends lend uncertainty regarding the severity of this activity over the next few hours. Farther southwest across NE, much higher confidence exists regarding the potential for severe. Numerous thunderstorms, some supercellular, have developed within 50mi north of the front. Hail algorithm suggests much of this activity is producing hail and with LLJ expected to strengthen into north-central KS later this evening, a continuation of elevated strong/severe is expected. Will add 15% severe for hail with these storms. ..Darrow.. 10/01/2019 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0755 PM CDT Mon Sep 30 2019 Valid 010100Z - 011200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER MS VALLEY AND CENTRAL PLAINS... ...SUMMARY... Isolated large hail and damaging gusts remain possible this evening across parts of the upper Mississippi Valley. A greater risk for hail is expected across portions of Nebraska. ...01z Update... Scattered thunderstorms have developed along pronounced front from the Arrowhead of MN - MSP - Martin County MN, near the IA border. This activity is struggling to attain severe levels, much in line with earlier CAMs regarding updraft strength/intensity. Even so, 00z sounding from MPX exhibits substantial SBCAPE with 50kt+ sfc-6km shear. Environmental parameters remain favorable for severe with this frontal activity; however, convective trends lend uncertainty regarding the severity of this activity over the next few hours. Farther southwest across NE, much higher confidence exists regarding the potential for severe. Numerous thunderstorms, some supercellular, have developed within 50mi north of the front. Hail algorithm suggests much of this activity is producing hail and with LLJ expected to strengthen into north-central KS later this evening, a continuation of elevated strong/severe is expected. Will add 15% severe for hail with these storms. ..Darrow.. 10/01/2019 Read more