Severe Storms

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0319 PM CDT Mon May 15 2023 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN MISSOURI...NORTHERN ARKANSAS...FAR SOUTHERN ILLINOIS...WESTERN KENTUCKY AND WESTERN AND MIDDLE TENNESSEE... CORRECTED GRAPHIC ...SUMMARY... Marginally severe thunderstorms producing a few strong wind gusts and hail will be possible today from parts of the Ozarks into the Tennessee Valley vicinity. ...20Z Update... Some adjustments to the categorical and probabilistic outlook lines have been made, but mostly just to account for the slow progression of the synoptic/sub-synoptic features and associated trends concerning destabilization. Please refer to the 1630Z outlook discussion (appended below) and the latest SPC mesoscale discussions for further details. ..Kerr.. 05/15/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon May 15 2023/ ...Ozarks to TN Valley vicinity... An upper ridge will persist over the Southeast much of today, while a rather nondescript/weak flow regime remains in place across the Plains. At the surface, a weak low/MCV is featured over eastern OK late this morning. This feature will slowly migrate east/northeast through southern MO through the period. Abundant boundary-layer moisture (surface dewpoints in the upper 60s to near 70 F) and heating into upper 70s/low 80s F will support weak to moderate destabilization ahead of the MCV. Deep-layer flow will remain light, though the MCV will likely enhance low/midlevel winds modestly, providing around 25 kt effective shear magnitudes. This should support some loosely organized, sporadically strong cells/bows. Strong/locally damaging gusts and hail will be the main hazards with this activity. While low-level flow will remain very weak, vertically veering winds in the lowest 1-2 km will produce very modestly curved hodographs with some minor SRH ahead of the MCV in conjunction with mean mixing ratios near 15-16 g/kg. Tornado potential is expected to remain very low, but a funnel cloud or brief spin-up could occur this afternoon, mainly across southern MO. Further east toward Middle TN into adjacent portions of northern AL/extreme northwest GA, shear profile will be even more modest, mainly relegating afternoon activity to pulse-like convection. However, stronger instability and a more deeply mixed boundary-layer could support potential for water-loaded downdrafts and isolated downbursts producing locally strong gusts with any more transient intense cells this afternoon. The strongest cells could also produce small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0319 PM CDT Mon May 15 2023 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN MISSOURI...NORTHERN ARKANSAS...FAR SOUTHERN ILLINOIS...WESTERN KENTUCKY AND WESTERN AND MIDDLE TENNESSEE... CORRECTED GRAPHIC ...SUMMARY... Marginally severe thunderstorms producing a few strong wind gusts and hail will be possible today from parts of the Ozarks into the Tennessee Valley vicinity. ...20Z Update... Some adjustments to the categorical and probabilistic outlook lines have been made, but mostly just to account for the slow progression of the synoptic/sub-synoptic features and associated trends concerning destabilization. Please refer to the 1630Z outlook discussion (appended below) and the latest SPC mesoscale discussions for further details. ..Kerr.. 05/15/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon May 15 2023/ ...Ozarks to TN Valley vicinity... An upper ridge will persist over the Southeast much of today, while a rather nondescript/weak flow regime remains in place across the Plains. At the surface, a weak low/MCV is featured over eastern OK late this morning. This feature will slowly migrate east/northeast through southern MO through the period. Abundant boundary-layer moisture (surface dewpoints in the upper 60s to near 70 F) and heating into upper 70s/low 80s F will support weak to moderate destabilization ahead of the MCV. Deep-layer flow will remain light, though the MCV will likely enhance low/midlevel winds modestly, providing around 25 kt effective shear magnitudes. This should support some loosely organized, sporadically strong cells/bows. Strong/locally damaging gusts and hail will be the main hazards with this activity. While low-level flow will remain very weak, vertically veering winds in the lowest 1-2 km will produce very modestly curved hodographs with some minor SRH ahead of the MCV in conjunction with mean mixing ratios near 15-16 g/kg. Tornado potential is expected to remain very low, but a funnel cloud or brief spin-up could occur this afternoon, mainly across southern MO. Further east toward Middle TN into adjacent portions of northern AL/extreme northwest GA, shear profile will be even more modest, mainly relegating afternoon activity to pulse-like convection. However, stronger instability and a more deeply mixed boundary-layer could support potential for water-loaded downdrafts and isolated downbursts producing locally strong gusts with any more transient intense cells this afternoon. The strongest cells could also produce small hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0319 PM CDT Mon May 15 2023 Valid 152000Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING ACROSS PARTS OF SOUTHERN MISSOURI...NORTHERN ARKANSAS...FAR SOUTHERN ILLINOIS...WESTERN KENTUCKY AND WESTERN AND MIDDLE TENNESSEE... CORRECTED GRAPHIC ...SUMMARY... Marginally severe thunderstorms producing a few strong wind gusts and hail will be possible today from parts of the Ozarks into the Tennessee Valley vicinity. ...20Z Update... Some adjustments to the categorical and probabilistic outlook lines have been made, but mostly just to account for the slow progression of the synoptic/sub-synoptic features and associated trends concerning destabilization. Please refer to the 1630Z outlook discussion (appended below) and the latest SPC mesoscale discussions for further details. ..Kerr.. 05/15/2023 .PREV DISCUSSION... /ISSUED 1112 AM CDT Mon May 15 2023/ ...Ozarks to TN Valley vicinity... An upper ridge will persist over the Southeast much of today, while a rather nondescript/weak flow regime remains in place across the Plains. At the surface, a weak low/MCV is featured over eastern OK late this morning. This feature will slowly migrate east/northeast through southern MO through the period. Abundant boundary-layer moisture (surface dewpoints in the upper 60s to near 70 F) and heating into upper 70s/low 80s F will support weak to moderate destabilization ahead of the MCV. Deep-layer flow will remain light, though the MCV will likely enhance low/midlevel winds modestly, providing around 25 kt effective shear magnitudes. This should support some loosely organized, sporadically strong cells/bows. Strong/locally damaging gusts and hail will be the main hazards with this activity. While low-level flow will remain very weak, vertically veering winds in the lowest 1-2 km will produce very modestly curved hodographs with some minor SRH ahead of the MCV in conjunction with mean mixing ratios near 15-16 g/kg. Tornado potential is expected to remain very low, but a funnel cloud or brief spin-up could occur this afternoon, mainly across southern MO. Further east toward Middle TN into adjacent portions of northern AL/extreme northwest GA, shear profile will be even more modest, mainly relegating afternoon activity to pulse-like convection. However, stronger instability and a more deeply mixed boundary-layer could support potential for water-loaded downdrafts and isolated downbursts producing locally strong gusts with any more transient intense cells this afternoon. The strongest cells could also produce small hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1245 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z Elevated highlights have been introduced for portions of Coastal New England. Here, the latest guidance consensus depicts dry and breezy conditions capable of supporting wildfire spread on a potentially widespread basis. By Tuesday afternoon, an upper trough will deepen over New England, with 50+ kts of northwesterly flow overspreading the region. The deepening upper trough will also encourage strengthening surface lee troughing, with surface west-southwesterly winds sustaining over 15 mph. Given the presence of a lingering deep, dry boundary layer extending up to 500 mb (per 12Z Day 1 observed regional soundings), surface heating will encourage RH to drop below 30 percent on a widespread basis (perhaps down to 20 percent locally). Finally, fuel guidance indicates 100-h fuel moisture values may drop into the 10-15 percent range as ERCs potentially exceed the 80th percentile in spots. This level of fuel receptiveness, along with the lack of forecast rainfall and anticipated dry and breezy conditions warrants the introduction of Elevated highlights. ..Squitieri.. 05/15/2023 .PREV DISCUSSION... /ISSUED 0201 AM CDT Mon May 15 2023/ ...Synopsis... Within the base of a midlevel low/trough over northern Quebec, strong deep-layer westerly flow will overspread the Northeast -- where a dry antecedent air mass is in place. A narrow corridor of partly cloudy skies from south-central NY into CT/MA will aid in deep boundary-layer mixing into the dry/enhanced flow aloft -- where 15-20 percent minimum RH is possible. These dry conditions, coupled with sustained westerly surface winds near 15 mph (with higher gusts) could yield elevated fire-weather conditions during the afternoon. Currently, these conditions appear too localized for highlights, though trends will be monitored. ...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 1245 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z Elevated highlights have been introduced for portions of Coastal New England. Here, the latest guidance consensus depicts dry and breezy conditions capable of supporting wildfire spread on a potentially widespread basis. By Tuesday afternoon, an upper trough will deepen over New England, with 50+ kts of northwesterly flow overspreading the region. The deepening upper trough will also encourage strengthening surface lee troughing, with surface west-southwesterly winds sustaining over 15 mph. Given the presence of a lingering deep, dry boundary layer extending up to 500 mb (per 12Z Day 1 observed regional soundings), surface heating will encourage RH to drop below 30 percent on a widespread basis (perhaps down to 20 percent locally). Finally, fuel guidance indicates 100-h fuel moisture values may drop into the 10-15 percent range as ERCs potentially exceed the 80th percentile in spots. This level of fuel receptiveness, along with the lack of forecast rainfall and anticipated dry and breezy conditions warrants the introduction of Elevated highlights. ..Squitieri.. 05/15/2023 .PREV DISCUSSION... /ISSUED 0201 AM CDT Mon May 15 2023/ ...Synopsis... Within the base of a midlevel low/trough over northern Quebec, strong deep-layer westerly flow will overspread the Northeast -- where a dry antecedent air mass is in place. A narrow corridor of partly cloudy skies from south-central NY into CT/MA will aid in deep boundary-layer mixing into the dry/enhanced flow aloft -- where 15-20 percent minimum RH is possible. These dry conditions, coupled with sustained westerly surface winds near 15 mph (with higher gusts) could yield elevated fire-weather conditions during the afternoon. Currently, these conditions appear too localized for highlights, though trends will be monitored. ...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 1245 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z Elevated highlights have been introduced for portions of Coastal New England. Here, the latest guidance consensus depicts dry and breezy conditions capable of supporting wildfire spread on a potentially widespread basis. By Tuesday afternoon, an upper trough will deepen over New England, with 50+ kts of northwesterly flow overspreading the region. The deepening upper trough will also encourage strengthening surface lee troughing, with surface west-southwesterly winds sustaining over 15 mph. Given the presence of a lingering deep, dry boundary layer extending up to 500 mb (per 12Z Day 1 observed regional soundings), surface heating will encourage RH to drop below 30 percent on a widespread basis (perhaps down to 20 percent locally). Finally, fuel guidance indicates 100-h fuel moisture values may drop into the 10-15 percent range as ERCs potentially exceed the 80th percentile in spots. This level of fuel receptiveness, along with the lack of forecast rainfall and anticipated dry and breezy conditions warrants the introduction of Elevated highlights. ..Squitieri.. 05/15/2023 .PREV DISCUSSION... /ISSUED 0201 AM CDT Mon May 15 2023/ ...Synopsis... Within the base of a midlevel low/trough over northern Quebec, strong deep-layer westerly flow will overspread the Northeast -- where a dry antecedent air mass is in place. A narrow corridor of partly cloudy skies from south-central NY into CT/MA will aid in deep boundary-layer mixing into the dry/enhanced flow aloft -- where 15-20 percent minimum RH is possible. These dry conditions, coupled with sustained westerly surface winds near 15 mph (with higher gusts) could yield elevated fire-weather conditions during the afternoon. Currently, these conditions appear too localized for highlights, though trends will be monitored. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON AND EVENING ACROSS PARTS OF CENTRAL AND EASTERN KENTUCKY...EASTERN TENNESSEE...SOUTHWESTERN INTO SOUTH CENTRAL VIRGINIA...WESTERN AND CENTRAL NORTH CAROLINA....UPSTATE SOUTH CAROLINA AND ADJACENT NORTHEASTERN GEORGIA... ...SUMMARY... Clusters of thunderstorms may form and gradually consolidate across parts of the Tennessee Valley and Cumberland Plateau through the Appalachian Piedmont Tuesday afternoon and evening. Some of these storms may initially be accompanied by a risk for severe hail, before strong wind gusts become the more prominent potential severe hazard. ...Synopsis... A vigorous short wave impulse digging around the western through southwestern periphery of a mid-level low, now digging into northern Quebec, may contribute to elongation of the low and/or amplification of larger-scale, positively tilted mid-level troughing across much of the Northeast during this period. As this occurs, it appears likely to be accompanied by a significant surface cold front, which is forecast to surge south of the St. Lawrence Valley and upper Great Lakes region, into the northern Mid Atlantic coast, upper Ohio and Mississippi Valleys by 12Z Wednesday. A stalled, or slower moving, and weaker preceding front, initially extending across the Mid Atlantic coast into the lower Ohio Valley and southern Great Plains, may advance southward into the Tennessee Valley and through the southern Mid Atlantic coast, in response to the progression of a weak frontal wave. Upstream of the broadly confluent mid-level regime evolving east of the Mississippi Valley, models indicate that mid-level ridging will build across British Columbia, with an embedded high evolving, in the wake of a significant short wave perturbation digging into the Canadian Prairies. It appears that the latter feature will be accompanied by lower/mid-tropospheric cyclogenesis, and another cold front which may advance across the international border to the east of the northern Rockies by 12Z Wednesday. ...Lower Ohio/Tennessee Valleys into Mid Atlantic... Along and ahead of the initially stalled or slow moving surface front, a seasonably moist boundary-layer across the lower Ohio and Tennessee Valleys is forecast to destabilize with daytime heating, while also advecting across the Appalachians, toward the Mid Atlantic, during the day. Despite the presence of only modestly cool mid-level temperatures, with generally weak lapse rates, this moisture may become supportive of mixed-layer CAPE on the order of 1000-2000 J/kg (with larger CAPE remaining west of the Appalachians) along the frontal zone. Beneath a corridor of strengthening westerly flow in the 850-500 mb layer (on the order of 30-50 kt), it appears that the environment will become potentially supportive of organized convective development. Initiation of storms may be aided by a couple of perturbations progressing through the evolving and amplifying larger-scale cyclonic mid-level flow, with convection tending to grow upscale and perhaps gradually consolidate into one east-southeastward propagating cluster and associated surface cold pool, accompanied by potentially damaging wind gusts. ..Kerr.. 05/15/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON AND EVENING ACROSS PARTS OF CENTRAL AND EASTERN KENTUCKY...EASTERN TENNESSEE...SOUTHWESTERN INTO SOUTH CENTRAL VIRGINIA...WESTERN AND CENTRAL NORTH CAROLINA....UPSTATE SOUTH CAROLINA AND ADJACENT NORTHEASTERN GEORGIA... ...SUMMARY... Clusters of thunderstorms may form and gradually consolidate across parts of the Tennessee Valley and Cumberland Plateau through the Appalachian Piedmont Tuesday afternoon and evening. Some of these storms may initially be accompanied by a risk for severe hail, before strong wind gusts become the more prominent potential severe hazard. ...Synopsis... A vigorous short wave impulse digging around the western through southwestern periphery of a mid-level low, now digging into northern Quebec, may contribute to elongation of the low and/or amplification of larger-scale, positively tilted mid-level troughing across much of the Northeast during this period. As this occurs, it appears likely to be accompanied by a significant surface cold front, which is forecast to surge south of the St. Lawrence Valley and upper Great Lakes region, into the northern Mid Atlantic coast, upper Ohio and Mississippi Valleys by 12Z Wednesday. A stalled, or slower moving, and weaker preceding front, initially extending across the Mid Atlantic coast into the lower Ohio Valley and southern Great Plains, may advance southward into the Tennessee Valley and through the southern Mid Atlantic coast, in response to the progression of a weak frontal wave. Upstream of the broadly confluent mid-level regime evolving east of the Mississippi Valley, models indicate that mid-level ridging will build across British Columbia, with an embedded high evolving, in the wake of a significant short wave perturbation digging into the Canadian Prairies. It appears that the latter feature will be accompanied by lower/mid-tropospheric cyclogenesis, and another cold front which may advance across the international border to the east of the northern Rockies by 12Z Wednesday. ...Lower Ohio/Tennessee Valleys into Mid Atlantic... Along and ahead of the initially stalled or slow moving surface front, a seasonably moist boundary-layer across the lower Ohio and Tennessee Valleys is forecast to destabilize with daytime heating, while also advecting across the Appalachians, toward the Mid Atlantic, during the day. Despite the presence of only modestly cool mid-level temperatures, with generally weak lapse rates, this moisture may become supportive of mixed-layer CAPE on the order of 1000-2000 J/kg (with larger CAPE remaining west of the Appalachians) along the frontal zone. Beneath a corridor of strengthening westerly flow in the 850-500 mb layer (on the order of 30-50 kt), it appears that the environment will become potentially supportive of organized convective development. Initiation of storms may be aided by a couple of perturbations progressing through the evolving and amplifying larger-scale cyclonic mid-level flow, with convection tending to grow upscale and perhaps gradually consolidate into one east-southeastward propagating cluster and associated surface cold pool, accompanied by potentially damaging wind gusts. ..Kerr.. 05/15/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON AND EVENING ACROSS PARTS OF CENTRAL AND EASTERN KENTUCKY...EASTERN TENNESSEE...SOUTHWESTERN INTO SOUTH CENTRAL VIRGINIA...WESTERN AND CENTRAL NORTH CAROLINA....UPSTATE SOUTH CAROLINA AND ADJACENT NORTHEASTERN GEORGIA... ...SUMMARY... Clusters of thunderstorms may form and gradually consolidate across parts of the Tennessee Valley and Cumberland Plateau through the Appalachian Piedmont Tuesday afternoon and evening. Some of these storms may initially be accompanied by a risk for severe hail, before strong wind gusts become the more prominent potential severe hazard. ...Synopsis... A vigorous short wave impulse digging around the western through southwestern periphery of a mid-level low, now digging into northern Quebec, may contribute to elongation of the low and/or amplification of larger-scale, positively tilted mid-level troughing across much of the Northeast during this period. As this occurs, it appears likely to be accompanied by a significant surface cold front, which is forecast to surge south of the St. Lawrence Valley and upper Great Lakes region, into the northern Mid Atlantic coast, upper Ohio and Mississippi Valleys by 12Z Wednesday. A stalled, or slower moving, and weaker preceding front, initially extending across the Mid Atlantic coast into the lower Ohio Valley and southern Great Plains, may advance southward into the Tennessee Valley and through the southern Mid Atlantic coast, in response to the progression of a weak frontal wave. Upstream of the broadly confluent mid-level regime evolving east of the Mississippi Valley, models indicate that mid-level ridging will build across British Columbia, with an embedded high evolving, in the wake of a significant short wave perturbation digging into the Canadian Prairies. It appears that the latter feature will be accompanied by lower/mid-tropospheric cyclogenesis, and another cold front which may advance across the international border to the east of the northern Rockies by 12Z Wednesday. ...Lower Ohio/Tennessee Valleys into Mid Atlantic... Along and ahead of the initially stalled or slow moving surface front, a seasonably moist boundary-layer across the lower Ohio and Tennessee Valleys is forecast to destabilize with daytime heating, while also advecting across the Appalachians, toward the Mid Atlantic, during the day. Despite the presence of only modestly cool mid-level temperatures, with generally weak lapse rates, this moisture may become supportive of mixed-layer CAPE on the order of 1000-2000 J/kg (with larger CAPE remaining west of the Appalachians) along the frontal zone. Beneath a corridor of strengthening westerly flow in the 850-500 mb layer (on the order of 30-50 kt), it appears that the environment will become potentially supportive of organized convective development. Initiation of storms may be aided by a couple of perturbations progressing through the evolving and amplifying larger-scale cyclonic mid-level flow, with convection tending to grow upscale and perhaps gradually consolidate into one east-southeastward propagating cluster and associated surface cold pool, accompanied by potentially damaging wind gusts. ..Kerr.. 05/15/2023 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1221 PM CDT Mon May 15 2023 Valid 161200Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON AND EVENING ACROSS PARTS OF CENTRAL AND EASTERN KENTUCKY...EASTERN TENNESSEE...SOUTHWESTERN INTO SOUTH CENTRAL VIRGINIA...WESTERN AND CENTRAL NORTH CAROLINA....UPSTATE SOUTH CAROLINA AND ADJACENT NORTHEASTERN GEORGIA... ...SUMMARY... Clusters of thunderstorms may form and gradually consolidate across parts of the Tennessee Valley and Cumberland Plateau through the Appalachian Piedmont Tuesday afternoon and evening. Some of these storms may initially be accompanied by a risk for severe hail, before strong wind gusts become the more prominent potential severe hazard. ...Synopsis... A vigorous short wave impulse digging around the western through southwestern periphery of a mid-level low, now digging into northern Quebec, may contribute to elongation of the low and/or amplification of larger-scale, positively tilted mid-level troughing across much of the Northeast during this period. As this occurs, it appears likely to be accompanied by a significant surface cold front, which is forecast to surge south of the St. Lawrence Valley and upper Great Lakes region, into the northern Mid Atlantic coast, upper Ohio and Mississippi Valleys by 12Z Wednesday. A stalled, or slower moving, and weaker preceding front, initially extending across the Mid Atlantic coast into the lower Ohio Valley and southern Great Plains, may advance southward into the Tennessee Valley and through the southern Mid Atlantic coast, in response to the progression of a weak frontal wave. Upstream of the broadly confluent mid-level regime evolving east of the Mississippi Valley, models indicate that mid-level ridging will build across British Columbia, with an embedded high evolving, in the wake of a significant short wave perturbation digging into the Canadian Prairies. It appears that the latter feature will be accompanied by lower/mid-tropospheric cyclogenesis, and another cold front which may advance across the international border to the east of the northern Rockies by 12Z Wednesday. ...Lower Ohio/Tennessee Valleys into Mid Atlantic... Along and ahead of the initially stalled or slow moving surface front, a seasonably moist boundary-layer across the lower Ohio and Tennessee Valleys is forecast to destabilize with daytime heating, while also advecting across the Appalachians, toward the Mid Atlantic, during the day. Despite the presence of only modestly cool mid-level temperatures, with generally weak lapse rates, this moisture may become supportive of mixed-layer CAPE on the order of 1000-2000 J/kg (with larger CAPE remaining west of the Appalachians) along the frontal zone. Beneath a corridor of strengthening westerly flow in the 850-500 mb layer (on the order of 30-50 kt), it appears that the environment will become potentially supportive of organized convective development. Initiation of storms may be aided by a couple of perturbations progressing through the evolving and amplifying larger-scale cyclonic mid-level flow, with convection tending to grow upscale and perhaps gradually consolidate into one east-southeastward propagating cluster and associated surface cold pool, accompanied by potentially damaging wind gusts. ..Kerr.. 05/15/2023 Read more

No Mesoscale Discussions are in effect as of Sun May 14 21:39:06 UTC 2023.

WW 0224 Status Updates
STATUS REPORT ON WW 224 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..WEINMAN..05/14/23 ATTN...WFO...LSX...ILX...PAH... STATUS REPORT FOR WS 224 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC001-005-009-013-017-021-025-027-047-049-051-055-059-061-065- 077-081-083-117-119-121-125-129-133-135-137-145-149-157-163-165- 167-169-171-173-189-191-193-199-142240- IL . ILLINOIS COUNTIES INCLUDED ARE ADAMS BOND BROWN CALHOUN CASS CHRISTIAN CLAY CLINTON EDWARDS EFFINGHAM FAYETTE FRANKLIN GALLATIN GREENE HAMILTON JACKSON JEFFERSON JERSEY MACOUPIN MADISON MARION MASON MENARD MONROE MONTGOMERY MORGAN PERRY PIKE RANDOLPH ST. CLAIR SALINE SANGAMON SCHUYLER SCOTT SHELBY WASHINGTON WAYNE WHITE WILLIAMSON MOC007-019-027-051-071-073-099-103-111-113-127-135-137-139-151- 157-163-173-183-186-189-205-219-510-142240- MO Read more

WW 224 SEVERE TSTM IL MO 142000Z - 150300Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 224 NWS Storm Prediction Center Norman OK 300 PM CDT Sun May 14 2023 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern and Central Illinois Central and Eastern Missouri * Effective this Sunday afternoon and evening from 300 PM until 1000 PM CDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible Scattered large hail events to 1.5 inches in diameter possible SUMMARY...Clusters of storms will continue to develop and intensify initially across east-central Missouri, as well as west-central/southwest Illinois this afternoon. The strongest storms will be capable of large hail and locally damaging winds. Over time, one or more semi-clusters of southeastward-moving storms could evolve by late afternoon/early evening with a continued damaging wind risk. The severe thunderstorm watch area is approximately along and 80 statute miles east and west of a line from 25 miles north northwest of Quincy IL to 10 miles west of Carbondale IL. 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 1.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 30020. ...Guyer Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0258 PM CDT Sun May 14 2023 Valid 142000Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE MID MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms capable of producing damaging wind gusts and hail are possible later this afternoon into this evening across parts of the mid Mississippi Valley. ...20Z Update... The Marginal Risk area has been trimmed from the south and expanded slightly eastward, based on the progression of an arc of convection associated with a compact cyclone moving across east TX. Otherwise, no changes have been made to the severe probabilities. Scattered strong to potentially severe thunderstorms remain possible across parts of the mid MS Valley into this evening, with a threat of locally damaging wind gusts and isolated hail. A more isolated severe threat remains evident across northeast TX, and from eastern KS into western MO. See MCD 792, MCD 793, MCD 794, and the previous outlook discussion below for more information. ..Dean.. 05/14/2023 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun May 14 2023/ ...Mid-Mississippi Valley including Missouri/Illinois... Thunderstorms are expected to develop/increase this afternoon initially across northern/eastern Missouri near a weak surface low and a southeastward-extending front, with additional/more isolated warm sector development across eastern Kansas and central/southern Missouri. Over time, storms should build southeastward along the low-level theta-e/CAPE axis into southern Illinois. Winds aloft are only modestly strong. Nevertheless, the combination of a moist and moderately unstable airmass and linear forcing mechanisms along the front may be sufficient for a few bowing structures posing a risk of locally damaging winds and hail. ...East Texas... Within a moist environment, a belt of moderately strong low/mid-level southerly winds will tend to persist and shift north-northeastward today on the eastern periphery of a weak low. Weak mid-level lapse rates along with cloud cover and existing precipitation will tend to limit overall destabilization, but a few stronger storms capable of water-loaded downbursts could materialize this afternoon across eastern Texas. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Sun May 14 2023 Valid 151200Z - 161200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 05/14/2023 .PREV DISCUSSION... /ISSUED 0155 AM CDT Sun May 14 2023/ ...Synopsis... In the wake of a departing midlevel trough, a belt of strong deep-layer west-northwesterly flow will extend from northern Canada east-southeastward into the northeastern United States. Along the southern periphery of this enhanced flow, a dry air mass will be in place from the Upper MS Valley eastward into the Great Lakes and Northeast. Boundary-layer heating/mixing through this corridor could yield 20-30 percent RH, which combined with breezy/gusty westerly surface winds, could support locally elevated fire-weather conditions over parts of the Upper MS Valley and Northeast (where fuels are modestly dry). However, the wildfire threat appears too localized for Elevated highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Sun May 14 2023 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE OZARKS AND VICINITY... ...SUMMARY... Isolated severe storms appear possible on Monday afternoon and evening across the Ozark region and vicinity. Locally damaging winds and isolated hail are expected to be the primary hazards. ...Ozarks and vicinity... A convectively enhanced midlevel shortwave trough is forecast to move from eastern OK into parts of the Ozarks on Monday, around the periphery of a weakening upper ridge over the Southeast. Meanwhile, an outflow-reinforced surface boundary is expected to become draped somewhere across southern MO/northern AR during the afternoon, with a weak surface low potentially developing along the front in response to the approaching shortwave. Rich low-level moisture and diurnal heating will support MLCAPE increasing into the 1000-2000 J/kg range (locally higher) by late afternoon with minimal capping. Scattered thunderstorm development is expected Monday afternoon in the vicinity of the front as the shortwave approaches the region. With modest deep-layer flow/shear in place, multicell clusters appear to be the most likely mode, though a marginal supercell cannot be ruled out where shear may be locally enhanced near the boundary. Locally damaging outflow/downburst gusts may be the most likely hazard, though isolated hail cannot be ruled out, despite generally weak midlevel lapse rates. ...Northwest... Scattered thunderstorms are expected Monday afternoon and evening across much of the Northwest, in association with a weakening mid/upper-level low that is forecast to become nearly stationary near the Pacific Northwest coast. With generally modest instability and deep-layer shear across the region, the organized severe-thunderstorm threat appears limited at this time, though small hail and gusty winds will be possible with the strongest storms. ..Dean.. 05/14/2023 Read more

WW 0223 Status Updates
STATUS REPORT ON WW 223 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..THORNTON..05/13/23 ATTN...WFO...DVN...DMX...FSD... STATUS REPORT FOR WT 223 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC011-015-021-025-027-035-041-049-057-073-075-077-079-083-087- 091-093-095-099-101-103-107-111-115-123-125-127-135-141-149-151- 153-157-161-169-171-177-179-181-183-187-197-132240- IA . IOWA COUNTIES INCLUDED ARE BENTON BOONE BUENA VISTA CALHOUN CARROLL CHEROKEE CLAY DALLAS DES MOINES GREENE GRUNDY GUTHRIE HAMILTON HARDIN HENRY HUMBOLDT IDA IOWA JASPER JEFFERSON JOHNSON KEOKUK LEE LOUISA MAHASKA MARION MARSHALL MONROE O'BRIEN PLYMOUTH POCAHONTAS POLK POWESHIEK SAC STORY TAMA VAN BUREN WAPELLO WARREN WASHINGTON WEBSTER WRIGHT 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 0223 Status Updates
STATUS REPORT ON WW 223 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..THORNTON..05/13/23 ATTN...WFO...DVN...DMX...FSD... STATUS REPORT FOR WT 223 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS IAC011-015-021-025-027-035-041-049-057-073-075-077-079-083-087- 091-093-095-099-101-103-107-111-115-123-125-127-135-141-149-151- 153-157-161-169-171-177-179-181-183-187-197-132240- IA . IOWA COUNTIES INCLUDED ARE BENTON BOONE BUENA VISTA CALHOUN CARROLL CHEROKEE CLAY DALLAS DES MOINES GREENE GRUNDY GUTHRIE HAMILTON HARDIN HENRY HUMBOLDT IDA IOWA JASPER JEFFERSON JOHNSON KEOKUK LEE LOUISA MAHASKA MARION MARSHALL MONROE O'BRIEN PLYMOUTH POCAHONTAS POLK POWESHIEK SAC STORY TAMA VAN BUREN WAPELLO WARREN WASHINGTON WEBSTER WRIGHT 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 223 TORNADO IA 131755Z - 140000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 223 NWS Storm Prediction Center Norman OK 1255 PM CDT Sat May 13 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Iowa * Effective this Saturday afternoon and evening from 1255 PM until 700 PM CDT. * Primary threats include... A couple tornadoes possible Scattered large hail events to 1.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms are expected to increase in intensity and coverage in the vicinity of a warm front that extends from northwest through southeast IA. Environmental conditions support supercells capable of hail and tornadoes. The tornado watch area is approximately along and 35 statute miles north and south of a line from 25 miles northwest of Storm Lake IA to 55 miles east of Ottumwa IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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 222... AVIATION...Tornadoes and 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 500. Mean storm motion vector 22020. ...Mosier Read more

WW 223 TORNADO IA 131755Z - 140000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 223 NWS Storm Prediction Center Norman OK 1255 PM CDT Sat May 13 2023 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Iowa * Effective this Saturday afternoon and evening from 1255 PM until 700 PM CDT. * Primary threats include... A couple tornadoes possible Scattered large hail events to 1.5 inches in diameter possible Isolated damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms are expected to increase in intensity and coverage in the vicinity of a warm front that extends from northwest through southeast IA. Environmental conditions support supercells capable of hail and tornadoes. The tornado watch area is approximately along and 35 statute miles north and south of a line from 25 miles northwest of Storm Lake IA to 55 miles east of Ottumwa IA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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 222... AVIATION...Tornadoes and 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 500. Mean storm motion vector 22020. ...Mosier Read more