Severe Storms

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Sat Aug 06 2022 Valid 071200Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTHERN ARIZONA... ...SUMMARY... Thunderstorms capable of isolated severe wind gusts are possible across parts of Arizona Sunday afternoon and evening. ...Arizona... Scattered thunderstorms are expected to develop Sunday afternoon across parts of Arizona, within a relatively moist and moderately unstable environment. Initial development is expected across the higher terrain, with east-northeasterly midlevel flow favoring the potential for outflow-driven clusters to move into the lower desert regions by evening, with an attendant risk of isolated severe wind gusts. ...CO Front Range into the central High Plains... Scattered to widespread thunderstorms are expected along the CO Front Range within a post frontal regime, with more isolated development possible across adjacent portions of the central High Plains. Veering wind profiles north of the front will support effective shear of 20-30 kt within a moderately unstable environment, and a couple of semi-organized storms will be possible, though a tendency for storm mergers is expected to limit the severe threat to some extent. ...Midwest into parts of the Great Lakes... Substantial convection is expected across parts of the Midwest during the D1/Saturday period into early Sunday, which casts considerable uncertainty regarding the severe potential later in the day. There is some potential for afternoon/evening redevelopment along any remnant outflow boundaries, and also along a cold front moving across parts of IA/MN. Stronger deep-layer shear is expected to remain north/west of the greater surface-based instability, but a few stronger cells/clusters will be possible across some portion of this area, and severe probabilities may eventually be needed, depending on shorter-term observational and guidance trends. ...Northern New England... Northern New England will be along the southern fringe of stronger midlevel flow on Sunday. While the environment is expected to remain relatively moist, very weak midlevel lapse rates will tend to limit buoyancy and thunderstorm coverage for much of the day. There is some chance for isolated storms to develop across the higher terrain (if sufficient heating can occur), and/or spread south of the international border by early evening. Should this occur, some locally damaging wind threat may result, though confidence remains too low for wind probabilities at this time. ..Dean.. 08/06/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Sat Aug 06 2022 Valid 061630Z - 071200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... A few severe thunderstorms may develop this afternoon and evening from the upper Mississippi Valley into the central High Plains. ...IA/MN/WI... Morning satellite imagery shows a canopy of cloud cover associated with a decaying MCS over MN/WI. The southern edge of clouds extends from northwest IA into far southern MN and southwest WI. Strong heating and ample low-level moisture will be present today to the south of this axis, with MLCAPE values expected to exceed 3000 J/kg with 20-30 knots of deep-layer mean flow. Most CAM solutions show scattered thunderstorms developing in this area by late afternoon, with a few supercell and organized multicell structures possible. Mid-level temperatures are quite warm and lapse rates are weak, suggesting that the hail risk will be limited. However, high PW values and steep low-level lapse rates will promote damaging wind gusts in the stronger cells. Therefore have added a small SLGT risk area to parts of the region. ...High Plains... Scattered high-based thunderstorms are expected to develop this afternoon and evening over the plains of eastern CO/WY and drift eastward. Forecast soundings show that winds aloft are rather strong over WY, but thermodynamics will be somewhat marginal. Isolated supercells will be possible with a risk of hail and damaging wind gusts, but the forecast coverage of intense storms appears to be in line with a MRGL category at this time. This will be re-evaluated at 20z. ..Hart/Weinman.. 08/06/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1047 AM CDT Sat Aug 06 2022 Valid 061700Z - 071200Z The previous forecast remains on track with only minor adjustments made based on trends in latest guidance. Morning water-vapor imagery reveals mid-level confluence zone along the CA/OR border that will provide weak ascent today. The 12 UTC MFR sounding sampled favorable buoyancy atop a somewhat dry boundary layer that should support a wet/dry mix of thunderstorms this afternoon. ...Willamette Valley... Dry conditions are expected this afternoon through the Willamette Valley with RH values falling as low as 20%. Terrain-augmented winds may reach near 15 mph and support areas of elevated conditions. While noted, this potential remains too localized for a broader risk area. ..Moore.. 08/06/2022 .PREV DISCUSSION... /ISSUED 1230 AM CDT Sat Aug 06 2022/ ...Synopsis... A mid-level short-wave trough will move across portions of the northern CONUS, from the Pacific Northwest to the northern Plains. Meanwhile, an upper-level ridge will remain quasi-stationary over the central CONUS with weak mid- to upper-level flow prevailing in most areas. At the surface, a cold front will enter portions of the northern/central High Plains. Ahead of this front, breezy southwesterly surface winds near 20 mph should develop during the afternoon across most of western Kansas and vicinity. However, RH values should generally remain above critical/elevated thresholds amid fuels that appear generally non-receptive to large-fire spread. ...Southern Oregon... An area delineating the potential for isolated dry thunderstorms has been introduced for the region. A narrow zone of convection should develop during the late afternoon hours amid dry/receptive fuels and PWAT values remaining below 0.75 inches. The highlighted area has been confined to portions of the region that received little appreciable rainfall yesterday. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Aug 5 18:04:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1210 PM CDT Fri Aug 05 2022 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL PLAINS AND UPPER MIDWEST... ...SUMMARY... A few strong to severe storms may affects parts of the central Plains and upper Mississippi Valley Saturday afternoon and evening. ...Synopsis... Upper ridging is forecast to be centered over the central Plains early Saturday morning, covering much of the Southwest, central/southern Plains, and MS Valley. This ridging is expected to remain largely in place throughout the day, with some modest dampening throughout its far northern periphery as a shortwave trough moves from Pacific Northwest into the northern High Plains. This shortwave trough will follow in the wake of another shortwave moving across the Hudson Bay/Ontario. This train of shortwave troughs will help maintain broad upper troughing over the Canadian Prairie Provinces and far northern High Plains/northern Plains, with modestly enhanced flow aloft extending through the base of this troughing from WY through the Upper Midwest/Upper Great Lakes. Surface pattern is expected to feature a cold front stretching from the MN arrowhead vicinity southwestward through central NE early Saturday morning. This front is forecast to progress gradually southward/southeastward during the day, ending the period extending from central WI southwestward into western KS. Interaction between this front and the warm and moist air mass across the central Plains and Upper MS Valley will support thunderstorm development throughout the day. ...Central Plains...Upper Midwest... Showers and thunderstorms will likely be ongoing Saturday morning to the north of the cold front mentioned in the synopsis, supported by warm-air advection across the frontal zone. Steep mid-level lapse rates will likely still be in place amid modest vertical shear, resulting in the potential for few updrafts capable of hail and/or a damaging downburst. This early morning activity should diminish as it moves northeastward, with additional thunderstorm development anticipated during the afternoon, both along the front and in its wake. Thunderstorm initiation along the front appears most probable from the north-central WI southwestward into north-central NE, where daytime heating will push temperatures in the upper 90s/low 100s amid mid to upper 60s dewpoints. Strong buoyancy will support intense updrafts, but the highest storm coverage may be displaced south of the stronger deep-layer vertical shear and high LCLs. These conditions suggests a mostly outflow-dominant storm mode, with a few damaging wind gusts are possible. Only exception is across WI and southeast MN, where vertical shear is expected to be strong enough for a few supercells. Here, isolated hail is possible in addition to damaging wind gusts. ..Mosier.. 08/05/2022 Read more

MD 1654 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHWEST AND WESTERN VA...SOUTHEAST WV...NORTHEAST TN...NORTHWEST NC
Mesoscale Discussion 1654 NWS Storm Prediction Center Norman OK 1211 PM CDT Fri Aug 05 2022 Areas affected...southwest and western VA...southeast WV...northeast TN...northwest NC Concerning...Severe potential...Watch unlikely Valid 051711Z - 051915Z Probability of Watch Issuance...20 percent SUMMARY...Isolated gusts 45-60 mph are possible and these gusts will likely be capable of localized pockets of wind damage. DISCUSSION...Visible-satellite imagery shows thunderstorms developing over the past hour near the ridge tops of the Appalachians. Surface conditions show temperatures warming through the upper 80s in the low elevations with dewpoints in the lower 70s. Continued heating will further steepen low-level lapse rates as temperatures warm into the 90s. NAM forecast soundings indicate 2000-3000 J/kg MLCAPE is present over southwest and western VA and surrounding states. This buoyancy magnitude appears to be adequately depicted based on midday surface observations compared to the RAP-based SPC Objective Analysis (1000-1500 J/kg MLCAPE). With PW 1.75 to 2 inches, ample water-loading potential is evident. The steepening of 0-3 km lapse rates in excess of 8 deg C/km will favor strong gust potential. A weak tropospheric wind profile will favor slow-moving, pulse-like storms. Isolated to widely scattered strong gusts 45-55 mph are probable with the stronger cores (locally up to around 60 mph) with pockets of wind damage the likely result. ..Smith/Hart.. 08/05/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LWX...RNK...PBZ...RLX...GSP...MRX... LAT...LON 36938205 37788098 39397883 39407824 39127786 38637788 37007916 35788167 35838209 36188227 36938205 Read more

MD 1654 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHWEST AND WESTERN VA...SOUTHEAST WV...NORTHEAST TN...NORTHWEST NC
Mesoscale Discussion 1654 NWS Storm Prediction Center Norman OK 1211 PM CDT Fri Aug 05 2022 Areas affected...southwest and western VA...southeast WV...northeast TN...northwest NC Concerning...Severe potential...Watch unlikely Valid 051711Z - 051915Z Probability of Watch Issuance...20 percent SUMMARY...Isolated gusts 45-60 mph are possible and these gusts will likely be capable of localized pockets of wind damage. DISCUSSION...Visible-satellite imagery shows thunderstorms developing over the past hour near the ridge tops of the Appalachians. Surface conditions show temperatures warming through the upper 80s in the low elevations with dewpoints in the lower 70s. Continued heating will further steepen low-level lapse rates as temperatures warm into the 90s. NAM forecast soundings indicate 2000-3000 J/kg MLCAPE is present over southwest and western VA and surrounding states. This buoyancy magnitude appears to be adequately depicted based on midday surface observations compared to the RAP-based SPC Objective Analysis (1000-1500 J/kg MLCAPE). With PW 1.75 to 2 inches, ample water-loading potential is evident. The steepening of 0-3 km lapse rates in excess of 8 deg C/km will favor strong gust potential. A weak tropospheric wind profile will favor slow-moving, pulse-like storms. Isolated to widely scattered strong gusts 45-55 mph are probable with the stronger cores (locally up to around 60 mph) with pockets of wind damage the likely result. ..Smith/Hart.. 08/05/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LWX...RNK...PBZ...RLX...GSP...MRX... LAT...LON 36938205 37788098 39397883 39407824 39127786 38637788 37007916 35788167 35838209 36188227 36938205 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1115 AM CDT Fri Aug 05 2022 Valid 051630Z - 061200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING OVER PARTS OF THE EASTERN DAKOTAS AND NORTHWEST MINNESOTA.... ...SUMMARY... Severe thunderstorms capable of damaging wind gusts and hail are expected today across parts of the Dakotas into Minnesota. Other more isolated thunderstorm wind gusts will occur from the central Appalachians into the Mid Atlantic region. ...Northern Plains... Morning surface analysis shows a weak cold front extending across the western Dakotas. This boundary will move eastward today and provide the focus for afternoon thunderstorm development. Strong heating, dewpoints near 70F, and steep mid-level lapse rates will yield MLCAPE values 2000-3000 J/kg. CAM solutions suggest storms will form by late afternoon and early evening from central SD into northwest MN. Deep-layer shear is sufficient for organized/supercell storms capable of severe wind gusts and hail through the evening. ...Mid Atlantic to Central Appalachians... Visible satellite imagery shows mostly clear skies from east TN into much of VA, where dewpoints in the 70s will result in afternoon MLCAPE values around 2000 J/kg. Mid level lapse rates are weak, and forecast soundings show weak winds aloft through column. Nevertheless, pulse and occasional multicell storm clusters will pose a risk of gusty and locally damaging wind gusts for a few hours this afternoon. ..Hart/Smith.. 08/05/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1056 AM CDT Fri Aug 05 2022 Valid 051700Z - 061200Z An isolated dry thunderstorm risk area is introduced to portions of northern CA into southern OR. Latest MRMS rainfall estimates suggest ongoing convection is a mix of wet/dry thunderstorms with pockets of wetting rainfall. Thunderstorm chances will persist into the afternoon as a weak mid-level disturbance moves into the northern Great Basin. Forecast soundings show inverted-V soundings with cloud bases near 2.5-3 km and PWAT values near 0.8 to 1.0 inch. These thermodynamic conditions are supportive of a mix of wet/dry thunderstorms over a region with receptive fuels and a history of recent fire starts. See the previous discussion below for additional forecast concerns. ..Moore.. 08/05/2022 .PREV DISCUSSION... /ISSUED 0157 AM CDT Fri Aug 05 2022/ ...Synopsis... An upper-level shortwave trough evident on water vapor imagery this morning over the Pacific Northwest is forecast to move eastward across southern Canada today. An associated surface low over Manitoba will deepen with a trailing surface trough/cold front draped southward into the northern Plains. While the enhanced surface pressure gradient across the region will lead to windy pre-frontal and post-frontal conditions across portions of the northern Plains, the overlap of strong winds with critical RH values appears unlikely, limiting fire weather concerns. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Thu Aug 4 17:41:01 UTC 2022.

MD 1650 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF THE CENTRAL APPALACHIANS INTO THE MID ATLANTIC
Mesoscale Discussion 1650 NWS Storm Prediction Center Norman OK 1214 PM CDT Thu Aug 04 2022 Areas affected...Parts of the central Appalachians into the Mid Atlantic Concerning...Severe potential...Watch unlikely Valid 041714Z - 041915Z Probability of Watch Issuance...20 percent SUMMARY...Storms capable of isolated damaging winds will increase in coverage this afternoon. DISCUSSION...Convection is increasing early this afternoon across eastern WV and northwest VA, with some increasing cumulus also noted across southern VA. Strong diurnal heating and rich low-level moisture will support MLCAPE increasing to near or above 2000 J/kg across the region this afternoon, as MLCINH erodes and storm coverage continues to increase with time. Deep-layer shear is generally expected to remain weak, but the thermodynamic environment will support a threat of isolated and potentially damaging downburst winds in association with the strongest storms. Midlevel cloudiness associated with an approaching MCV may result in a relative minimum in storm coverage across parts of western VA, but some potential exists for a loosely organized storm cluster to develop and spread across northern VA into adjacent portions of MD, as outflows consolidate with time. Due to the generally disorganized nature of the threat, watch issuance is considered unlikely at this time. ..Dean/Grams.. 08/04/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...LWX...RNK...PBZ...RLX... LAT...LON 38468071 39207948 39657882 39687754 39667714 38847666 38137656 37767666 37707725 37777777 37937799 38157825 38397869 38507916 38277993 38188027 38098056 38068093 38248100 38468071 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1209 PM CDT Thu Aug 04 2022 Valid 051200Z - 061200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN PLAINS AS WELL AS THE MID-ATLANTIC... ...SUMMARY... Isolated severe wind gusts or marginal hail will be possible Friday afternoon across parts of the northern Plains, and over parts of Virginia and Maryland. ...Synopsis... Upper ridging is forecast to prevail across the southern half of the CONUS on Friday, with the center of the ridge drifting northeastward into the central Plains. A shortwave trough is expected to progress eastward across the Canadian Prairie Provinces into Ontario. The gradient between the southern CONUS upper ridging and this shortwave trough will act to enhanced the westerly flow aloft from the Pacific Northwest into the Upper MS Valley. A surface low will precede the Canadian shortwave, beginning the period over central Manitoba before moving northeastward into northern Ontario and the Hudson Bay. An attendant cold front is expected to sweep southeastward across the northern Plains and Upper Midwest, leading to thunderstorms development during the afternoon and evening. ...Northern Plains... Strong diurnal heating is anticipated ahead of the front across the northern Plains on Friday, with temperatures reaching the upper 90s and low 100s. Despite deep boundary-layer mixing associated with this heating, dewpoints are expected to remain in the 60s, which will support moderate to strong instability within the pre-frontal air mass. Late afternoon thunderstorm initiation is anticipated along the front, with robust updrafts developing quickly. Some of the enhanced mid-level flow discussed in the synopsis will extend over the region, supporting around 30 to 40 kt of deep-layer vertical shear, which is enough for occasional supercell storm structures. However, the linear character of the forcing for ascent along the front coupled with high storm coverage suggests a discrete, supercellular mode would be difficult to maintain. These factors, coupled with the high-based character of the storms, suggest a mainly multicellular/outflow-dominant mode, with damaging wind gusts as the main severe threat. There is enough overlap between the buoyancy and shear to support a hail threat as well, particularly early in the storm life cycle. ...Mid-Atlantic... Afternoon thunderstorm development is expected over much of the Mid-Atlantic, fostered by diurnal heating, ample low-level moisture, and modest ascent. The ascent over the region will be a combination of low-level confluence and weak large-scale lift attendant to any convectively inducted vorticity maxima from overnight activity farther west. All of these factors maximize over northern VA and vicinity, where the greatest probability for a few damaging wind gusts exists. ..Mosier.. 08/04/2022 Read more

MD 1649 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF CENTRAL/EASTERN OH...WESTERN PA...NORTHERN WV PANHANDLE
Mesoscale Discussion 1649 NWS Storm Prediction Center Norman OK 1158 AM CDT Thu Aug 04 2022 Areas affected...Parts of central/eastern OH...western PA...northern WV Panhandle Concerning...Severe potential...Watch unlikely Valid 041658Z - 041900Z Probability of Watch Issuance...5 percent SUMMARY...Thunderstorms capable of isolated damaging wind gusts are possible this afternoon. DISCUSSION...Convection is gradually increasing in coverage and intensity early this afternoon, along and ahead of a weak surface boundary draped from northern OH into northwest PA. With deep-layer shear expected to remain weak, convection is expected to remain relatively disorganized. However, as MLCAPE increases into the 1500-2000 J/kg range and low-level lapse rates steepen with time, the strongest cells/clusters may be capable of producing isolated damaging wind as they spread northeastward this afternoon. Watch issuance is not expected at this time. ..Dean/Grams.. 08/04/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...PBZ...RLX...CLE...ILN... LAT...LON 40348335 40848174 41368018 41767927 41147927 40028049 39708171 39658264 39688299 39848355 40138366 40348335 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Thu Aug 04 2022 Valid 041700Z - 051200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN MONTANA... The previous forecast remains valid with only minor adjustments for the latest hi-res guidance. Critical fire weather conditions are expected with a strong frontal passage across portions of northern MT. Isolated dry thunderstorms are also expected within dry fuels across southern MT. Otherwise, please see the prior discussion for more details. ..Lyons.. 08/04/2022 .PREV DISCUSSION... /ISSUED 0141 AM CDT Thu Aug 04 2022/ ...Synopsis... A midlevel shortwave trough is forecast to move eastward across the northern Rockies today. Strong west-southwesterly flow aloft associated with this feature will overspread the Pacific Northwest and northern Idaho/Montana. In response at the surface, low pressure will deepen over Alberta and Saskatchewan. ...Northern Rockies and adjacent High Plains... Along the southern periphery of the surface low, a swath of 20-25 mph sustained westerly surface winds are expected across parts of north-central MT. These strong winds, coupled with a hot/deeply-mixed boundary layer (10-15 percent minimum RH) will lead to critical fire-weather conditions. In addition, mixed wet-dry thunderstorms should spread eastward across the northern Rockies, accompanied by locally strong outflow winds. Given the expected high cloud bases and relatively fast storm motions (over 30 mph), limited rainfall accumulation is expected, supporting isolated dry thunderstorm potential. ...Pacific Northwest... Deep boundary-layer mixing in the presence of strong westerly flow aloft combined with downslope warming/drying in the lee of the Cascades will result in 15-20 mph sustained westerly surface winds and 15-20 percent RH. Given receptive fuels from WA into OR, elevated to locally critical conditions can be expected. ...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 1121 AM CDT Thu Aug 04 2022 Valid 041630Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CONUS... ...SUMMARY... Isolated severe thunderstorms, mainly in the form of damaging winds, are possible into early evening from the Ohio Valley into parts of the Mid-Atlantic and New England, western portions of South Dakota and Nebraska, Montana, and the western Colorado Plateau. ...NE/SD... Strong surface heating and deep mixing will occur along a surface lee trough across from the NE Panhandle into southwest SD. Though boundary-layer moisture will be somewhat marginal, a narrow corridor of MLCAPE approaching 1500 J/kg should develop with minimal MLCIN. Most CAM guidance suggest a few storms should form near the surface trough during the late afternoon. Inverted-v thermodynamic profiles and moderately elongated hodographs could support a couple high-based supercells capable of isolated severe wind and hail for a few hours into the early evening. ...MT... An amplified upper trough centered on BC will shift east across the Canadian Rockies towards SK through 12Z tomorrow. As this occurs, a surface cyclone will deepen over southeast AB into southern SK, with a trailing cold front sharpening over MT. With PW values largely between 0.5 to 0.75 inches this morning, boundary-layer moisture will be quite limited. Very deep boundary-layer mixing with meager buoyancy atop that along the surface front should be just enough to promote very high-based convection from southwest to central MT. While the bulk of stronger mid-level westerlies will be confined to the cool side of the surface front, adequate strengthening will support semi-organized skeletal clusters capable of isolated severe outflow gusts spreading east-northeast. ...OH Valley into the Mid-Atlantic and New England... A remnant MCV over far southern IL should drift east into western KY. To the northeast of this MCV, broad but weak mid-level southwesterlies will exist within a seasonably rich PW moisture plume. The persistence of weak convective outflows, differential surface heating, and terrain will support a broad swath of scattered thunderstorms. Relatively greater potential for damaging microbursts in predominately pulse and slow-moving multicell clusters should exist from the Upper OH Valley into the Northeast/Mid-Atlantic where MLCAPE can exceed 2000 J/kg. But the lack of greater vertical shear will be detrimental to an organized severe threat. See MCD 1648 and later MCDs this afternoon for additional short-term forecast information. ...Western CO Plateau vicinity... A belt of enhanced mid-level easterlies becoming more southeasterly later today will persist to the north of an MCV drifting west across the Lower CO Valley. Scattered thunderstorms are expected to develop northwestward off the Mogollon Rim across the western CO Plateau and spread towards the southern Great Basin. Marginally severe hail will possible in initial updrafts transitioning to mainly a marginally severe wind threat later. ..Grams/Smith.. 08/04/2022 Read more

MD 1648 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTH-CENTRAL PA INTO SOUTHERN/CENTRAL NY
Mesoscale Discussion 1648 NWS Storm Prediction Center Norman OK 1119 AM CDT Thu Aug 04 2022 Areas affected...North-central PA into southern/central NY Concerning...Severe potential...Watch unlikely Valid 041619Z - 041815Z Probability of Watch Issuance...20 percent SUMMARY...Locally damaging winds are possible as thunderstorms spread northeastward this afternoon. DISCUSSION...An arc of convection has moved from western into north-central PA through the morning, with occasional 30-35 kt gusts noted. While deep-layer shear is generally weak across the region, unidirectional southwesterly flow may be sufficient to maintain loosely organized convection in association with this arc and related cold pool as it moves northeastward into a destabilizing environment, with an attendant threat of locally damaging wind gusts. Additional storm development is expected downstream into parts of southern/central NY this afternoon, which may also pose a localized damaging wind threat as low-level lapse rates steepen with time. With the threat expected to remain relatively isolated and disorganized, watch issuance is considered unlikely. ..Dean/Grams.. 08/04/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ALY...BGM...BUF...CTP... LAT...LON 42647697 43107539 43147492 42867454 42197508 41507610 41137662 40967706 40777809 41447879 41787899 42647697 Read more

No watches are valid as of Wed Aug 3 17:53:02 UTC 2022.

No Mesoscale Discussions are in effect as of Wed Aug 3 17:53:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1213 PM CDT Wed Aug 03 2022 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE OH VALLEY...AND CENTRAL MT... ...SUMMARY... Thunderstorms capable of isolated damaging wind gusts are expected over portions of the Ohio Valley as well as over central Montana on Thursday. ...Synopsis... Expansive upper ridging is forecast to be centered over the southern High Plains early Thursday morning, covering much of the southern half of the CONUS. This upper ridging is expected to persist throughout the period, relegating any stronger westerly flow to the northern CONUS, in particular the corridor from the Pacific Northwest into the Upper MS Valley/Upper Great Lakes. A shortwave trough will progress through this westerly flow aloft, remaining mainly on the Canadian side of the international border. Afternoon/evening thunderstorms are possible across MT as the ascent and increasing mid-level moisture attendant to this shortwave foster thunderstorm development. The central and eastern CONUS will be devoid of any large-scale synoptic features, but a convectively induced shortwave trough may be in place over the Mid MS Valley early in the period, induced by overnight thunderstorms. This shortwave is then forecast to progress northeastward through the OH Valley during the day. ...OH Valley... Overnight thunderstorms upstream of the region will greatly influence the overall severe potential Thursday, contributing significantly to both the strength of the shortwave trough expected to move through the region as well as the position of any outflow boundaries. Current expectation is for the convectively induced shortwave trough to track northeastward through the region during the afternoon, interacting with the moist and buoyant air mass to foster the development of numerous to widespread thunderstorms. Modestly enhanced low to mid-level flow may accompany this shortwave, supporting the potential for a few stronger, more organized storms capable of damaging wind gusts. ...Central MT... Strong boundary-layer mixing is anticipated ahead of the approaching shortwave trough. Destabilization resultant from this mixing as well as increasing mid-level moisture will result in meager buoyancy. Afternoon thunderstorm development is anticipated as the southern periphery of the shortwave glances the region. Moderate vertical shear will aid in updraft persistence, with the high-based character of these storms contributing to a risk for damaging wind gusts. ...Great Basin/Four Corners... Scattered to numerous thunderstorms are expected within the moist Monsoonal regime beneath the expansive upper ridge. Modest vertical shear should result in a predominantly pulse/multicellular storm mode, limiting updraft duration and overall strength. The only exception is over northern AZ, where the combination of shear and buoyancy may be enough to support a severe storm or two. However, uncertainty regarding coverage precludes introducing any severe probabilities with this outlook. ...Northern ME... Southern periphery of a shortwave trough moving through Quebec will contribute to increased forcing for ascent as well as stronger mid-level flow across the region. Scattered thunderstorm development is anticipated during afternoon, with the deep westerly flow aloft contributing to the potential for a few stronger storms capable of damaging wind gusts. Current expectation is for overall severe coverage too remain less than 5%. ..Mosier.. 08/03/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1122 AM CDT Wed Aug 03 2022 Valid 031630Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LOWER MO VALLEY TO THE GREAT LAKES... ...SUMMARY... Scattered damaging winds will be possible from the Great Lakes to the Lower Missouri Valley through this evening. ...Northern IL/southeast WI to Lower MI... An MCV evident in east-central IA will move into Lower MI by early evening. A broken swath of stratiform and deep convection is ongoing immediately ahead of this MCV in eastern IA, northeast across northern/central Lower MI. Robust boundary-layer heating is underway ahead of large-scale convective outflow still spreading east of this midday activity in IL, with a plume of large buoyancy anticipated as MLCAPE increases to 3000-4000 J/kg. Much of the convection may remain to the cool side of the large-scale convective outflow (at least in the short-term), but there is potential for clusters to eventually consolidate along the leading edge of the differential heating corridor. While stronger mid-level westerlies will generally reside over Lower MI (with a gradient from north to south), the DMX VWP sampled 40-45 kt 700-500 mb westerlies in the wake of the MCV. This should support increasingly organized convection this afternoon, even behind the broader large-scale convective outflow. Sporadic strong to severe wind gusts producing swaths of scattered damage appears possible this afternoon. This threat should linger into early evening with line segments that spread eastward. ...Mid-MS/Lower MO Valleys... Most morning guidance suggest ongoing showers and isolated thunderstorms in the wake of the leading east-central IA MCV should hold off on intensifying until the early evening time frame. A low-amplitude shortwave impulse over the Mid-MO Valley should drift east-southeast, while low-level convergence should tend to strengthen towards early evening along southern portion of a bifurcated frontal zone. Weaker but a more northwesterly component to mid-level flow should yield slower storm motions in multicell clusters that tend to propagate south-southeast in MO/IL. With a plume of large buoyancy in the warm/moist sector, scattered damaging wind gusts will be possible well into the evening, before gradually waning overnight. ...Southern AZ... Late morning convection is ongoing across parts of southeast AZ and this lowers confidence in the degree of boundary-layer heating and convective redevelopment off the higher terrain later today. Morning CAM guidance generally provides mixed signals on the degree of convective coverage during the late afternoon and evening. Conditionally, adequate speed shear from the mid to upper levels within a belt of east-southeasterlies around the Four Corners anticyclone could support a threat for marginally severe wind and some hail this evening. ...Southeast States... Very localized damaging winds are possible within pulse microbursts over a large swath of the Southeast. Minimal deep-layer shear will mitigate potential for organized clustering. ..Grams/Lyons.. 08/03/2022 Read more