Severe Storms

MD 0839 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR MUCH OF SOUTHERN FLORIDA
Mesoscale Discussion 0839 NWS Storm Prediction Center Norman OK 1031 AM CDT Fri May 20 2022 Areas affected...much of southern Florida Concerning...Severe potential...Watch unlikely Valid 201531Z - 201800Z Probability of Watch Issuance...20 percent SUMMARY...Scattered to numerous storms are expected by afternoon, with locally damaging wind gusts or marginally severe hail. DISCUSSION...A moist and unstable air mass is already in place across southern FL, with PWAT over 2.00" and no capping inversion. Early day storms have left a cooled air mass across the central Peninsula, with heating continuing to the south, which is resulting in MUCAPE over 3000 J/kg. Storms are already forming off the Gulf and Atlantic coasts, with expanding showers over land. Just 1-2 more hours of heating will likely result in a rapid expansion of convection, perhaps spreading northwestward with strong outflow. However, wind fields are weak and storm motion may be erratic. Water-loaded downdrafts may produce locally damaging gusts, and the strong instability and cool midlevel temperatures may support brief periods of marginal hail. ..Jewell/Hart.. 05/20/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MFL...MLB...KEY...TBW... LAT...LON 25767999 25148022 25138050 25078112 25208128 25858178 26588233 27288268 27848290 28068278 27938235 27628162 27388055 27258014 26807995 25767999 Read more

MD 0838 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR MUCH OF CENTRAL PENNSYLVANIA INTO FAR NORTHERN MARYLAND
Mesoscale Discussion 0838 NWS Storm Prediction Center Norman OK 0939 AM CDT Fri May 20 2022 Areas affected...much of central Pennsylvania into far northern Maryland Concerning...Severe potential...Watch likely Valid 201439Z - 201615Z Probability of Watch Issuance...80 percent SUMMARY...The severe threat is increasing across portions of central PA into MD. Damaging gusts and perhaps a few tornadoes may accompany the strongest, longer lived storms. A WW issuance will be needed within the next couple of hours. DISCUSSION...A remnant mid-level MCV (evident via water vapor imagery and 700-500 mb objective analysis fields) is currently located just west of the OH/PA border and continues to track eastward towards central PA, and is expected to support more robust convective initiation in the next few hours. Immediately ahead of the MCV center lies a highly sheared low-level environment, with recent PBZ VAD data showing relatively long, curved low-level hodographs and over 300 m2/s2 of associated 0-1km SRH. At the moment, buoyancy remains scant across portions of western into central PA. However, modest breaks in the clouds are contributing to modest surface heating, with mid 60s F surface temperatures already noted across central PA, with low 70s F along the PA/MD border. With surface dewpoints around 60F across several locales, RAP forecast soundings suggest temperatures need to warm into the lower 70s for appreciable buoyancy to develop given the presence of relatively poor (5.5-6.5 C/km) low and mid-level lapse rates. While buoyancy is expected to initially be marginal (i.e. at or below 1000 J/kg MLCAPE), localized deep-layer ascent and strong low-level shear associated with the approaching MCV should support at least a few strong to severe storms developing early this afternoon. Damaging gusts and perhaps a few tornadoes will be the primary concerns, though a brief instance or two of marginally severe hail cannot be completely ruled out with the longer-lived, persistent rotating updrafts. A WW issuance will be needed within the next couple of hours to address the severe threat. ..Squitieri/Hart.. 05/20/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...BGM...CTP...LWX...PBZ... LAT...LON 39507942 40487929 41477881 41867804 42007731 41887681 41487648 40907628 40257618 39787629 39547651 39437720 39317819 39507942 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Fri May 20 2022 Valid 201300Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF LOWER MICHIGAN...THE NORTHERN MID-ATLANTIC...AND A SMALL PART OF THE SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms are expected to be most concentrated over portions of Lower Michigan, the northern Mid-Atlantic, and a small part of the southern Plains. ...Synopsis... In mid/upper levels, positively tilted mean troughing will continue from a cyclone over Hudson Bay southwestward across the northern Plains and northern Great Basin region. A tightening of the height gradient aloft and commensurate increase in southwest flow is expected from the southern Rockies to the upper Great Lakes, as heights rise over the Eastern CONUS. Within those height rises, however, a shortwave trough and accompanying MCV -- arising from south-central High Plains convection a couple days ago and persisting now across OH -- will cross PA today, before reaching the southern NY/NJ region around 00Z, and eastward over southern New England, Long/Block Islands, and the adjoining Atlantic tonight. The 11Z surface analysis showed a seasonally strong cold front from a triple point over southern WI southwestward through a low over south-central KS, then over northwestern OK, the TX Panhandle, and northeastern NM. A wavy warm front -- somewhat diffuse west of the Appalachians thanks to outflow from MCV-related convection to its south -- was drawn from that triple point across central Lower MI, northeastern OH, northeastern WV, and northern VA. This warm front should move northward through Lower MI today prior to cold frontal passage, while also moving northward over southern/eastern PA and NJ. By 00Z the cold front should extend from Lower MI to near a line from ORD-STL-TUL-SPS-LVS. A dryline should intersect the front over northwest TX and extend south-southwestward to the Rio Grande shortly upstream from DRT. By 12Z, the front should reach northwestern OH, southern IL, north-central TX, and southeastern to central NM, overtaking the retreating dryline over west-central TX. Relative maxima in severe potential will occur in two nodes near the front, over Lower MI and the Red River region, with isolated, likely nocturnal severe potential from mostly elevated convection near the front in between. ...Lower MI... Scattered thunderstorms are expected to develop this afternoon -- perhaps in multiple episodes - ahead of the surface cold front, from west of central/northern Lake Michigan across central/northern Lower MI. The most favorable buoyancy/shear parameter space for severe thunderstorms -- including a few supercells with a tornado threat, damaging winds and large to significant hail -- will be across central/northern Lower MI. A combination of convergence near the cold front and boundary-layer heating in the warm sector will contribute to thunderstorm development, along with outflow/differential-heating boundaries on the mesobeta scale. Low-level warm/moist advection will aid in airmass recovery behind a pool of outflow produced by earlier MCV/MCS passage to the south of the area. Surface dew points commonly in the 60s F, diurnal heating, favorable low/middle-level lapse rates, and a deep troposphere will contribute to MLCAPE building into the 2000-3000 J/kg range, amidst supercell-favorable shear. Hail models applied to, and analog data closely associated with, these thermodynamic and wind profiles suggest any supercells will pose a threat of 2+ inch hail; therefore, a significant-hail area was added. Density of the tornado threat is more uncertain, with time series of forecast soundings suggesting some veering of near-surface winds and shrinking of hodographs right as the cap breaks. Still, a mesobeta-scale area of greater potential may develop, and observational trends and 12Z guidance will be monitored for considering ENH-level probabilities in succeeding outlooks. ...Northern Mid-Atlantic... Scattered thunderstorms -- some severe -- should develop just ahead of the MCV and along/south of the warm front, as the MCV moves across PA today. Damaging to severe gusts, isolated large hail, and a few tornadoes are possible. Large-scale lift on a mesoscale spatial scale will immediately precede the MCV, as will a corridor of relatively maximized low-level shear and enhanced 700-500-mb flow. These and relatively backed winds near the warm-frontal zone will contribute to favorable vertical shear for supercell and especially bow-echo organization. Meanwhile, moisture/theta-e advection and diurnal heating -- behind a swath of precursory morning clouds/convection now crossing the region -- should destabilize the boundary layer and weaken MLCINH sufficiently to support the severe threat. Peak preconvective MLCAPE in the 1500-2500 J/kg range is possible in central PA, decreasing eastward toward the Jersey Shore. However, even with lesser buoyancy, a cold-pool-driven, compact MCS may develop and persist eastward to near the coastline, sustained by forced ascent of at least marginally unstable parcels on the leading edge. ...Southern OK/north TX... Scattered strong-severe thunderstorms should develop this afternoon and persist into evening near the front and east of the dryline, over parts of southern OK and adjoining north TX. Severe hail/gusts will be possible. A favorably unstable moist warm-sector boundary layer will develop, with surface dewpoints in the upper 60s to near 70 F, and strong heating yielding a well-mixed subcloud layer despite the moisture content. MLCAPE of 3500-4500 J/kg appears probable, much of it in layers suitable for both hail growth and lightning generation. Low-level and deep shear will be weak, limiting modes to clustered, multicellular, and perhaps temporarily cold-pool-forced in character. With weak mid/upper winds expected, rapidly collapsing cores with considerable precip loading and severe gusts are possible. Overall, the threat should diminish after dark, though a few strong-severe storms may persist well into the evening given available moisture and steep low/middle-level lapse rates away from convectively modified air masses. ..Edwards/Kerr.. 05/20/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Fri May 20 2022 Valid 201300Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF LOWER MICHIGAN...THE NORTHERN MID-ATLANTIC...AND A SMALL PART OF THE SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms are expected to be most concentrated over portions of Lower Michigan, the northern Mid-Atlantic, and a small part of the southern Plains. ...Synopsis... In mid/upper levels, positively tilted mean troughing will continue from a cyclone over Hudson Bay southwestward across the northern Plains and northern Great Basin region. A tightening of the height gradient aloft and commensurate increase in southwest flow is expected from the southern Rockies to the upper Great Lakes, as heights rise over the Eastern CONUS. Within those height rises, however, a shortwave trough and accompanying MCV -- arising from south-central High Plains convection a couple days ago and persisting now across OH -- will cross PA today, before reaching the southern NY/NJ region around 00Z, and eastward over southern New England, Long/Block Islands, and the adjoining Atlantic tonight. The 11Z surface analysis showed a seasonally strong cold front from a triple point over southern WI southwestward through a low over south-central KS, then over northwestern OK, the TX Panhandle, and northeastern NM. A wavy warm front -- somewhat diffuse west of the Appalachians thanks to outflow from MCV-related convection to its south -- was drawn from that triple point across central Lower MI, northeastern OH, northeastern WV, and northern VA. This warm front should move northward through Lower MI today prior to cold frontal passage, while also moving northward over southern/eastern PA and NJ. By 00Z the cold front should extend from Lower MI to near a line from ORD-STL-TUL-SPS-LVS. A dryline should intersect the front over northwest TX and extend south-southwestward to the Rio Grande shortly upstream from DRT. By 12Z, the front should reach northwestern OH, southern IL, north-central TX, and southeastern to central NM, overtaking the retreating dryline over west-central TX. Relative maxima in severe potential will occur in two nodes near the front, over Lower MI and the Red River region, with isolated, likely nocturnal severe potential from mostly elevated convection near the front in between. ...Lower MI... Scattered thunderstorms are expected to develop this afternoon -- perhaps in multiple episodes - ahead of the surface cold front, from west of central/northern Lake Michigan across central/northern Lower MI. The most favorable buoyancy/shear parameter space for severe thunderstorms -- including a few supercells with a tornado threat, damaging winds and large to significant hail -- will be across central/northern Lower MI. A combination of convergence near the cold front and boundary-layer heating in the warm sector will contribute to thunderstorm development, along with outflow/differential-heating boundaries on the mesobeta scale. Low-level warm/moist advection will aid in airmass recovery behind a pool of outflow produced by earlier MCV/MCS passage to the south of the area. Surface dew points commonly in the 60s F, diurnal heating, favorable low/middle-level lapse rates, and a deep troposphere will contribute to MLCAPE building into the 2000-3000 J/kg range, amidst supercell-favorable shear. Hail models applied to, and analog data closely associated with, these thermodynamic and wind profiles suggest any supercells will pose a threat of 2+ inch hail; therefore, a significant-hail area was added. Density of the tornado threat is more uncertain, with time series of forecast soundings suggesting some veering of near-surface winds and shrinking of hodographs right as the cap breaks. Still, a mesobeta-scale area of greater potential may develop, and observational trends and 12Z guidance will be monitored for considering ENH-level probabilities in succeeding outlooks. ...Northern Mid-Atlantic... Scattered thunderstorms -- some severe -- should develop just ahead of the MCV and along/south of the warm front, as the MCV moves across PA today. Damaging to severe gusts, isolated large hail, and a few tornadoes are possible. Large-scale lift on a mesoscale spatial scale will immediately precede the MCV, as will a corridor of relatively maximized low-level shear and enhanced 700-500-mb flow. These and relatively backed winds near the warm-frontal zone will contribute to favorable vertical shear for supercell and especially bow-echo organization. Meanwhile, moisture/theta-e advection and diurnal heating -- behind a swath of precursory morning clouds/convection now crossing the region -- should destabilize the boundary layer and weaken MLCINH sufficiently to support the severe threat. Peak preconvective MLCAPE in the 1500-2500 J/kg range is possible in central PA, decreasing eastward toward the Jersey Shore. However, even with lesser buoyancy, a cold-pool-driven, compact MCS may develop and persist eastward to near the coastline, sustained by forced ascent of at least marginally unstable parcels on the leading edge. ...Southern OK/north TX... Scattered strong-severe thunderstorms should develop this afternoon and persist into evening near the front and east of the dryline, over parts of southern OK and adjoining north TX. Severe hail/gusts will be possible. A favorably unstable moist warm-sector boundary layer will develop, with surface dewpoints in the upper 60s to near 70 F, and strong heating yielding a well-mixed subcloud layer despite the moisture content. MLCAPE of 3500-4500 J/kg appears probable, much of it in layers suitable for both hail growth and lightning generation. Low-level and deep shear will be weak, limiting modes to clustered, multicellular, and perhaps temporarily cold-pool-forced in character. With weak mid/upper winds expected, rapidly collapsing cores with considerable precip loading and severe gusts are possible. Overall, the threat should diminish after dark, though a few strong-severe storms may persist well into the evening given available moisture and steep low/middle-level lapse rates away from convectively modified air masses. ..Edwards/Kerr.. 05/20/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0756 AM CDT Fri May 20 2022 Valid 201300Z - 211200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF LOWER MICHIGAN...THE NORTHERN MID-ATLANTIC...AND A SMALL PART OF THE SOUTHERN PLAINS... ...SUMMARY... Severe thunderstorms are expected to be most concentrated over portions of Lower Michigan, the northern Mid-Atlantic, and a small part of the southern Plains. ...Synopsis... In mid/upper levels, positively tilted mean troughing will continue from a cyclone over Hudson Bay southwestward across the northern Plains and northern Great Basin region. A tightening of the height gradient aloft and commensurate increase in southwest flow is expected from the southern Rockies to the upper Great Lakes, as heights rise over the Eastern CONUS. Within those height rises, however, a shortwave trough and accompanying MCV -- arising from south-central High Plains convection a couple days ago and persisting now across OH -- will cross PA today, before reaching the southern NY/NJ region around 00Z, and eastward over southern New England, Long/Block Islands, and the adjoining Atlantic tonight. The 11Z surface analysis showed a seasonally strong cold front from a triple point over southern WI southwestward through a low over south-central KS, then over northwestern OK, the TX Panhandle, and northeastern NM. A wavy warm front -- somewhat diffuse west of the Appalachians thanks to outflow from MCV-related convection to its south -- was drawn from that triple point across central Lower MI, northeastern OH, northeastern WV, and northern VA. This warm front should move northward through Lower MI today prior to cold frontal passage, while also moving northward over southern/eastern PA and NJ. By 00Z the cold front should extend from Lower MI to near a line from ORD-STL-TUL-SPS-LVS. A dryline should intersect the front over northwest TX and extend south-southwestward to the Rio Grande shortly upstream from DRT. By 12Z, the front should reach northwestern OH, southern IL, north-central TX, and southeastern to central NM, overtaking the retreating dryline over west-central TX. Relative maxima in severe potential will occur in two nodes near the front, over Lower MI and the Red River region, with isolated, likely nocturnal severe potential from mostly elevated convection near the front in between. ...Lower MI... Scattered thunderstorms are expected to develop this afternoon -- perhaps in multiple episodes - ahead of the surface cold front, from west of central/northern Lake Michigan across central/northern Lower MI. The most favorable buoyancy/shear parameter space for severe thunderstorms -- including a few supercells with a tornado threat, damaging winds and large to significant hail -- will be across central/northern Lower MI. A combination of convergence near the cold front and boundary-layer heating in the warm sector will contribute to thunderstorm development, along with outflow/differential-heating boundaries on the mesobeta scale. Low-level warm/moist advection will aid in airmass recovery behind a pool of outflow produced by earlier MCV/MCS passage to the south of the area. Surface dew points commonly in the 60s F, diurnal heating, favorable low/middle-level lapse rates, and a deep troposphere will contribute to MLCAPE building into the 2000-3000 J/kg range, amidst supercell-favorable shear. Hail models applied to, and analog data closely associated with, these thermodynamic and wind profiles suggest any supercells will pose a threat of 2+ inch hail; therefore, a significant-hail area was added. Density of the tornado threat is more uncertain, with time series of forecast soundings suggesting some veering of near-surface winds and shrinking of hodographs right as the cap breaks. Still, a mesobeta-scale area of greater potential may develop, and observational trends and 12Z guidance will be monitored for considering ENH-level probabilities in succeeding outlooks. ...Northern Mid-Atlantic... Scattered thunderstorms -- some severe -- should develop just ahead of the MCV and along/south of the warm front, as the MCV moves across PA today. Damaging to severe gusts, isolated large hail, and a few tornadoes are possible. Large-scale lift on a mesoscale spatial scale will immediately precede the MCV, as will a corridor of relatively maximized low-level shear and enhanced 700-500-mb flow. These and relatively backed winds near the warm-frontal zone will contribute to favorable vertical shear for supercell and especially bow-echo organization. Meanwhile, moisture/theta-e advection and diurnal heating -- behind a swath of precursory morning clouds/convection now crossing the region -- should destabilize the boundary layer and weaken MLCINH sufficiently to support the severe threat. Peak preconvective MLCAPE in the 1500-2500 J/kg range is possible in central PA, decreasing eastward toward the Jersey Shore. However, even with lesser buoyancy, a cold-pool-driven, compact MCS may develop and persist eastward to near the coastline, sustained by forced ascent of at least marginally unstable parcels on the leading edge. ...Southern OK/north TX... Scattered strong-severe thunderstorms should develop this afternoon and persist into evening near the front and east of the dryline, over parts of southern OK and adjoining north TX. Severe hail/gusts will be possible. A favorably unstable moist warm-sector boundary layer will develop, with surface dewpoints in the upper 60s to near 70 F, and strong heating yielding a well-mixed subcloud layer despite the moisture content. MLCAPE of 3500-4500 J/kg appears probable, much of it in layers suitable for both hail growth and lightning generation. Low-level and deep shear will be weak, limiting modes to clustered, multicellular, and perhaps temporarily cold-pool-forced in character. With weak mid/upper winds expected, rapidly collapsing cores with considerable precip loading and severe gusts are possible. Overall, the threat should diminish after dark, though a few strong-severe storms may persist well into the evening given available moisture and steep low/middle-level lapse rates away from convectively modified air masses. ..Edwards/Kerr.. 05/20/2022 Read more

No watches are valid as of Thu May 19 15:06:06 UTC 2022.

MD 0826 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL INTO EASTERN MISSOURI AND SOUTHWEST ILLINOIS
Mesoscale Discussion 0826 NWS Storm Prediction Center Norman OK 1005 AM CDT Thu May 19 2022 Areas affected...central into eastern Missouri and southwest Illinois Concerning...Severe potential...Watch possible Valid 191505Z - 191730Z Probability of Watch Issuance...40 percent SUMMARY...Storms may produce sporadic hail over the next several hours, eventually affecting the St. Louis area and crossing into Illinois. DISCUSSION...Strong storms persist in the warm advection regime ahead of a prominent MCV, with sporadic hail cores noted. This leading cluster of storms is currently moving east/northeastward, embedded within a larger-scale area of deep theta-e advection, which in itself is also shifting northeast. Therefore, the trend of pulsing hail cores should persist today, and may strengthen later this afternoon as instability is maximized from heating. Steep lapse rates aloft and sufficient deep-layer shear will continue to favor hail cores, but a wind risk could develop out of this activity at which time a watch would become more likely. ..Jewell/Hart.. 05/19/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...ILX...LSX...SGF... LAT...LON 38459227 38859208 39249159 39589037 39548967 39528913 39328846 38738799 37968796 37618805 37308838 37198953 37348999 37519067 37649122 37669162 37769202 38459227 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0724 AM CDT Thu May 19 2022 Valid 191300Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON INTO EARLY TONIGHT FOR NORTHERN IA...SOUTHEASTERN MN AND WESTERN WI... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY FROM SOUTHERN MO TO THE LOWER OH VALLEY AND THE CAROLINAS... ...SUMMARY... Isolated very large hail, damaging winds, and a couple of tornadoes will be possible later this afternoon into early tonight across northern Iowa, southeastern Minnesota and western Wisconsin. Occasional large hail, damaging winds, and a couple of tornadoes may also occur this afternoon from southern Missouri into southern Illinois, with at least isolated large hail/damaging winds farther east into the Carolinas. ...IA/MN/WI late this afternoon into tonight... A deep midlevel trough will move generally eastward along the international border from MT to MN by the end of the period. Downstream from the strengthening midlevel jet, initial lee cyclogenesis this morning across southwest SD will develop eastward to southern MN this evening and northwest WI tonight. East of the cyclone, a warm front will develop northward across IA/southern MN/WI through the afternoon/evening. The more probable area for initial storm development late this afternoon/evening will be east of the surface cyclone, along and north of the warm front in the zone of stronger ascent/warm advection with gradually increasing low-level moisture. Other storms will likely form this evening farther southwest along the trailing cold front. Uncertainty in this outlook area is related to the remnant MCS and well-developed MCV moving across northeast OK/southeast KS/southwest MO, which has intercepted the richer (near 70 F) dewpoints along the diffuse baroclinic zone straddling the KS/OK and MO/AR borders. This leaves residual low-mid 60s dewpoints across eastern KS and southeastern NE to the north of the MCS, which is below the more aggressive model forecasts of moisture return. Thus, the low-level moisture spreading into IA/MN/WI through the day is likely to be somewhat marginal for a more substantial tornado threat, when also considering the effects of afternoon mixing. Steep lapse rates and MLCAPE in excess of 2500 J/kg, as well as relatively long hodographs with low-level clockwise turning, will support supercells capable of producing very large hail initially. Storms should tend to evolve into clusters and line segments with more of a damaging wind threat by late evening. As previously discussed, the tornado threat will depend on the degree of low-level moisture return, which at the moment appears more supportive of a typical (5%) outlook area. ...Central/southern MO/IL through late evening... A well-developed MCV from overnight convection is approaching southwest MO, and will likely persist while continuing east-northeastward through the day, in response to gradual backing of midlevel flow related to upstream amplification of the trough over the northern Rockies. The MCV will track along a residual baroclinic zone and corridor of 68-72 F boundary-layer dewpoints with MLCAPE of 3000-4000 J/kg, which will support the potential for continued latent heating and maintenance of the MCV through the day. Associated convection will likely undergo diurnal intensification since the richer low-level moisture is already present in advance of this system. A couple of tornadoes, large hail, and damaging winds will all be possible with embedded clusters/supercells coinciding with MCV-related enhancements to the wind profiles. ...KY/TN into the Carolinas through late afternoon/evening... A midlevel shortwave trough is moving over the southern Appalachians this morning. As the low levels warm/moisten across the Carolinas today, at least isolated thunderstorm development is expected in advance of this trough. Midlevel lapse rates of 7.5-8 C/km, MLCAPE at or above 2000 J/kg and straight hodographs with 30-35 kt effective bulk shear will support a mix of multicell clusters and supercells capable of producing large hail and damaging winds, mainly this afternoon/evening. Farther west, storm development is a bit less certain to the west of the Appalachians shortwave trough, and well east of the MO MCV. Daytime heating/mixing could support isolated storm development across TN/KY this afternoon, and perhaps a few storms this evening/early tonight in the warm advection zone across northern KY/southern IN, east of the weakening MCV. ..Thompson/Leitman.. 05/19/2022 Read more

No watches are valid as of Wed May 18 13:36:01 UTC 2022.

No Mesoscale Discussions are in effect as of Wed May 18 13:36:01 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0730 AM CDT Wed May 18 2022 Valid 181300Z - 191200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR KY...NORTHEAST MN/NORTHWEST WI...AND SOUTHEAST CO INTO THE OK PANHANDLE... ...SUMMARY... A few severe thunderstorms with damaging winds and large hail are expected this afternoon/evening across Kentucky, northeast Minnesota, and from southeast Colorado into the Oklahoma Panhandle. ...KY to southern MO this afternoon/evening... An MCV from overnight convection will move eastward from MO to the OH Valley through this evening. The ongoing convection with the MCV is elevated, and the MCV should slightly outpace surface-based destabilization through early afternoon. By mid afternoon, low-level warming/moistening along the southwest flank of the MCV should support severe storm development across KY. Here, boundary-layer dewpoints in the mid 60s and afternoon temperatures in the low-mid 80s (south of any linger cold pool/outflow) will support MLCAPE near 2000 J/kg, in a zone of low-level warm advection beneath 50 kt midlevel westerly flow. Resultant hodograph structures will favor a broken west-east band of storms, some of which could be supercells across western/central KY. Damaging winds, large hail to golf ball size, and a tornado or two will all be possible. The spatial and temporal window of opportunity for severe storms is somewhat limited, and any delays in low-level destabilization would reduce the severe threat. Father west, isolated thunderstorm development will be possible this evening along the effective baroclinic zone across far southern MO. Forcing for ascent will be weak/shallow and confined to the front, so storm development/coverage is uncertain. However, midlevel lapse rates of 8-9 C/km, MLCAPE greater than 3000 J/kg, and midlevel flow near 40 kt will support a conditional threat for large hail and damaging winds. ...Southeast CO to the OK Panhandle late this afternoon/evening... A cluster of high-based storms appears probable across southeast CO by mid-late afternoon, immediately east of the mountains in a zone of weak upslope flow and strong surface heating/deep mixing. Some modest enhancement to midlevel flow with a subtle shortwave trough moving across CO, and inverted-V profiles with DCAPE greater than 1200 J/kg, will favor strong downdrafts and the potential for a storm cluster with occasional severe outflow gusts of 60-70 mph from southeast CO into the OK Panhandle through late evening. ...Northeast MN/northwest WI this afternoon/evening... An embedded speed max over ND this morning will progress east-southeastward to MN by this evening, as an accompanying/weak surface cyclone likewise develops east-southeastward from southern MB across northern MN. Despite limited low-level moisture on the larger scale, a corridor of low 50s dewpoints combined with surface heating beneath steep midlevel lapse rates and cool midlevel temperatures (colder than -20 C at 500 mb) will support MLCAPE approaching 1000 J/kg with minimal convective inhibition. Effective bulk shear of 30-40 kt with mainly straight hodographs and the moderate buoyancy appear sufficient for a few storms (a couple of which could be low-end supercells) to produce hail near 1 inch diameter and wind damage with outflow gusts up to 60 mph for a few hours this afternoon/evening. ..Thompson/Leitman.. 05/18/2022 Read more

No watches are valid as of Tue May 17 13:59:02 UTC 2022.

MD 0799 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL/EASTERN NE...FAR WEST-CENTRAL IA
Mesoscale Discussion 0799 NWS Storm Prediction Center Norman OK 0856 AM CDT Tue May 17 2022 Areas affected...Central/Eastern NE...Far West-Central IA Concerning...Severe potential...Watch unlikely Valid 171356Z - 171600Z Probability of Watch Issuance...20 percent SUMMARY...Isolated hail possible across central and eastern NE this morning. DISCUSSION...A robust elevated thunderstorm continues over northeast NE, although some modest updraft weakening has been noted recently. This thunderstorm developed on the far eastern edge of the steep lapse rate plume and at the nose of the modest low-level jet. Some limited ascent may have also been provided by a weak shortwave trough moving into the central Plains. Some additional thunderstorms have initiated farther west across central NE, although these updrafts are not as intense as the northeast NE storms yet. Deep cumulus exists all the way into far southwest NE. Low-level stability remains in place within the downstream air mass, although diurnal heating will weaken convective inhibition with time. Even so, current observational trends and mid-level moistening noted within forecast soundings suggest these area of storms could persist. Severe coverage is currently expected to remain isolated, limiting the need for a watch in short-term, but observational trends will be monitored closely. ..Mosier/Grams.. 05/17/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...FSD...OAX...GID...LBF... LAT...LON 41870071 42379796 42519691 42469613 42169554 41879538 41439544 41189590 40719660 40379728 40159836 40350003 41870071 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 AM CDT Tue May 17 2022 Valid 171300Z - 181200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT FROM EASTERN NE TO NORTHEAST KS...SOUTHWEST IA...AND NORTHWEST MO... ...SUMMARY... Scattered very large hail in excess of 2 inches in diameter, damaging thunderstorm winds to 70 mph, and a couple of tornadoes will be possible this evening into tonight from eastern Nebraska into northeast Kansas, southwest Iowa, and northwest Missouri. ...NE/KS/MO late this afternoon into tonight... A complex, largely zonal flow regime with subtle embedded speed maxima will affect the central CONUS through tonight. A weak southern stream trough will drift eastward over NM/southern CO, while a downstream MCVs from overnight convection move eastward from OK/KS to MO/AR today. The primary feature of interest this period is a subtle trough over WY/MT early this morning that will crest the flat ridge over the High Plains and progress east-southeastward to the middle MO Valley this evening into tonight. Associated lee cyclogenesis is expected today near the CO/KS border, and the remnant lee cyclone will develop south-southeastward toward the TX Panhandle tonight as a cold front moves southeastward across CO/NE/KS. Some temporary disruptions to the low-level moisture field have occurred overnight across OK in the wake of weakening convection and the MCVs with heat bursts, but this drying should wane as storms dissipate. Thereafter, a corridor of mid 60s boundary-layer dewpoints will establish across eastern KS into southeast NE by this evening. When the cold front intercepts the richer moisture and larger buoyancy by late evening from northeastern NE into northern KS, thunderstorm development is expected. Storms will subsequently spread southeastward overnight into the corridor of richer moisture and MLCAPE of 2000-3000 J/kg, aided by warm advection on the nose of a 30-40 kt low-level jet. The large buoyancy and steep midlevel lapse rates/large DCAPE will favor precipitation-loaded downdrafts capable of producing wind damage. Profiles will also potentially favor very large hail, though this threat depends largely on maintaining supercell structures within the larger area of convection. Any tornado threat will likely depend on at least mid 60s dewpoints making it into NE, and on maintaining semi-discrete supercells into late evening, or with line-embedded mesovortices. ...Southeast WY to the southeast TX Panhandle this evening... A few high-based thunderstorms will be possible this afternoon/evening in association with surface heating/deep mixing and the influences of a shortwave trough crossing WY, and a southern stream trough moving eastward from NM/CO. Any storms/clusters that form in this corridor will be capable of producing isolated severe outflow gusts for a few hours late this afternoon/evening, given inverted-V profiles. ..Thompson/Leitman.. 05/17/2022 Read more

WW 0226 Status Updates
STATUS FOR WATCH 0226 HAS NOT BEEN ISSUED YET Read more

WW 226 SEVERE TSTM NY PA LO 161525Z - 162000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 226 NWS Storm Prediction Center Norman OK 1125 AM EDT Mon May 16 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western to central New York Northeast Pennsylvania Lake Ontario * Effective this Monday morning and afternoon from 1125 AM until 400 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely Isolated large hail events to 1.5 inches in diameter possible SUMMARY...Intensifying storms are expected into this afternoon as activity spreads northeast from central Pennsylvania and western New York, with a mix of damaging winds and hail anticipated. The severe thunderstorm watch area is approximately along and 65 statute miles east and west of a line from 55 miles north northeast of Syracuse NY to 10 miles south southeast of Wilkesbarre PA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && OTHER WATCH INFORMATION...CONTINUE...WW 225... 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 450. Mean storm motion vector 24035. ...Grams Read more

MD 0781 CONCERNING SEVERE THUNDERSTORM WATCH 225...226... FOR CENTRAL/EASTERN PA...CENTRAL NY
Mesoscale Discussion 0781 NWS Storm Prediction Center Norman OK 1022 AM CDT Mon May 16 2022 Areas affected...Central/Eastern PA...Central NY Concerning...Severe Thunderstorm Watch 225...226... Valid 161522Z - 161645Z The severe weather threat for Severe Thunderstorm Watch 225, 226 continues. SUMMARY...Threat for damaging wind gusts continues across central PA. Isolated hail is also possible across south-central NY before the threat trends more towards damaging wind gusts. DISCUSSION...Updrafts embedded within the line of showers and thunderstorms moving across central PA has shown sporadic intensification over the past hour or so, with only limited updraft maintenance/duration thus far. Heating downstream will help boost instability, with strong updrafts becoming more prevalent. Threat for damaging wind gusts across this region continues. A few stronger updrafts have also developed within a warm-air advection wing over north-central PA into south-central NY, to the north and east of the deeper cores over central PA. The environment supports a marginal hail risk with this initial development, with wind damage becoming the primary risk as storms become more surface-based with time. ..Mosier/Grams.. 05/16/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BGM...BUF...CTP... LAT...LON 40937765 42007772 42467739 43187672 43127591 42687533 42187506 41657506 41317558 40917605 40007719 40937765 Read more

WW 0225 Status Updates
STATUS FOR WATCH 0225 HAS NOT BEEN ISSUED YET Read more

WW 225 SEVERE TSTM PA 161345Z - 161800Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 225 NWS Storm Prediction Center Norman OK 945 AM EDT Mon May 16 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Central Pennsylvania * Effective this Monday morning and afternoon from 945 AM until 200 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph possible SUMMARY...An emerging low-topped convective line across southwest Pennsylvania should intensify as it spreads east-northeast into early afternoon with strong gusts producing scattered tree damage the main threat. The severe thunderstorm watch area is approximately along and 60 statute miles east and west of a line from 50 miles north of Williamsport PA to 45 miles southwest of Harrisburg PA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). 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 inch. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 400. Mean storm motion vector 24030. ...Grams Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0731 AM CDT Mon May 16 2022 Valid 161300Z - 171200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM LATE MORNING THROUGH THE AFTERNOON FROM CENTRAL/EASTERN NY TO THE MID-ATLANTIC... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON INTO EARLY TONIGHT FROM EASTERN NM INTO THE TX PANHANDLE... ...SUMMARY... Scattered to numerous severe storms with damaging winds, a couple of tornadoes and isolated large hail are expected from late morning through the afternoon from central/eastern New York to the Mid_Atlantic. Damaging winds and isolated large hail will also be possible this afternoon and early tonight from eastern New Mexico into the Texas Panhandle. ...NY to the Mid-Atlantic from late morning to late afternoon... A midlevel shortwave trough over the OH Valley this morning will progress east-northeastward over the Mid-Atlantic and New England by tonight, as an associated surface cyclone deepens across the Saint Lawrence Valley and a trailing cold front likewise moves eastward and offshore overnight. Low-mid 60s boundary-layer dewpoints will spread northward ahead of the front, and pockets of surface heating will boost buoyancy by afternoon (MLCAPE of 1000-1500 J/kg). Deep-layer flow/vertical shear will increase with the approach of the midlevel trough from the west, contributing to an environment supportive of organized line segments and some supercell structures from late morning through the afternoon. Thunderstorms are expected to increase in coverage/intensity by late morning from the Finger Lakes region southward along the leading edge of the pre-frontal convective band moving into western PA this morning. These storms will subsequently spread eastward across NY and the Mid-Atlantic through late afternoon, and other storms could form farther west and southwest along the synoptic cold front, assuming sufficient cloud breaks occur by midday. The presence of organized convective bands and strengthening wind profiles suggest that wind damage with peak gusts of 55-70 mph will be a common threat this afternoon, west of any cooling marine influence. The threat for significant (75+ mph) gusts is more questionable given rather modest downdraft potential (DCAPE generally less than 500 J/kg) and low-midlevel flow no stronger than 30-40 kt. Otherwise, low-level shear may be strong enough to support a couple of tornadoes with pre-frontal supercells or circulations embedded in line segments, and the stronger storms may also produce isolated large hail of 1 to 1.5 inches in diameter. ...Southern High Plains this afternoon into early tonight... Low-level moisture has spread westward into eastern NM this morning on post-frontal easterly flow. Weak lee cyclogenesis and heating/mixing within the initially moist air mass will reduce convective inhibition this afternoon and allow scattered high-based thunderstorm development across eastern NM, and storms will gradually grow upscale and spread eastward on consolidating outflows. Inverted-V profiles with large DCAPE (near 1500 J/kg) will favor scattered severe outflow gusts, some of which may approach 75 mph prior to the convection slowly weakening early tonight across the TX Panhandle. ...Northern Rockies areas afternoon/evening... Subtle embedded speed maxima will continue to move from the northern Great Basin/Pacific Northwest to the northern Rockies, atop a weak baroclinic zone from central ID to southwest MT. A lingering low-midlevel moisture plume and surface heating in cloud breaks will support MLCAPE up to about 500 J/kg, within a corridor of effective bulk shear of 30-40 kt and largely straight hodographs. This environment will support widely scattered storms this afternoon/evening in the vicinity of the Beartooth Mountains, some of which could have low-end/splitting supercell characteristics with gusty outflow winds and marginally severe hail. Farther south, a few high-based storms may form this afternoon across extreme northeast NV and northwest UT, in advance of a subtle shortwave trough now near the northeast CA/NV border. Inverted-V profiles will favor strong outflow gusts with any deep convection in this corridor this afternoon/evening. ..Thompson/Leitman.. 05/16/2022 Read more