Severe Storms

No watches are valid as of Mon Jul 4 16:47:01 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Jul 4 16:47:01 UTC 2022.

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Mon Jul 04 2022 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE UPPER MS VALLEY/SOUTHWEST GREAT LAKES AND MT TO THE WESTERN DAKOTAS... ...SUMMARY... A few tornadoes and scattered damaging are possible from late afternoon through this evening centered on a portion of the Upper Mississippi Valley and southwest Great Lakes regions. Scattered large hail and isolated severe wind gusts are possible across parts of Montana into the western Dakotas from late afternoon through tonight. ...Upper MS Valley and southwest Great Lakes... A non-severe MCS is ongoing from western WI to the IA/IL border area. While the northern portion will likely further decay, remnants of the southern portion may persist across northern IL into IN this afternoon. Weak mid-level lapse rates and just-in-time moisture return should limit more widespread intensification potential, but isolated damaging wind gusts will be possible into late afternoon as the boundary layer further destabilizes. In the wake of the MCS and its attendant convectively induced shortwave impulse, large-scale ascent should be suppressed to the northwest of the low-level warm theta-e advection regime that is expected to persist from the Mid-MO Valley to southern WI. While there is low confidence in timing of redevelopment, areal extent will likely be focused near the IA/MN/WI/IL border. The degree of boundary-layer destabilization is questionable and its plausible that redeveloping convection will remain slightly elevated atop it. In addition, convective mode should tend to evolve into a west/east-oriented cluster. But rather enlarged low-level hodograph curvature owing to the southwesterly jet and modest surface temperature-dew point spreads favor a conditional threat for a few tornadoes. Consolidation of clusters into a forward-propagating MCS is possible tonight across northern IL into northwest IN with scattered damaging winds becoming the primary threat until convection weakens overnight. ...MT to the Dakotas... Despite minor weak mid-level height rises, presence of 50s surface dew points banked up to the northern Rockies will foster scattered thunderstorm development by late afternoon off the higher terrain in MT. More isolated thunderstorms will likely initiate off the Black Hills and are possible in north-central/northeast ND near a weak surface low. A belt of enhanced mid-level southwesterlies to westerlies will be maintained downstream of the weakening closed low near northwest WA. This will foster 40-50 kt effective bulk shear supporting potential for several supercells with mid-level updraft rotation. Larger buoyancy should be confined to southern SD into southeast ND, more muted values from 750-1500 J/kg are expected to the northwest. This will likely be a limiting factor to greater intensities with significant hail and wind potential expected to be very isolated/conditional. Large hail should be the primary threat with more isolated swaths of severe wind gusts focused on eastern MT into southwest ND this evening/tonight. ..Grams/Wendt.. 07/04/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Mon Jul 04 2022 Valid 041300Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE NORTHERN ROCKIES/PLAINS AND OVER PORTIONS OF THE MIDWEST AND GREAT LAKES REGIONS... ...SUMMARY... Isolated to scattered severe thunderstorms are expected over parts of the northern Rockies/Plains and over portions of the Midwest and Great Lakes regions this Independence Day. Large hail and damaging winds should be the main threats, with a tornado or two possible in the Midwest. ...Synopsis... The large-scale pattern in mid/upper levels will continue to feature mean troughing over northwestern North America, southward across the Pacific west of CA. Within that regime, a small cyclone is evident in moisture-channel imagery over the coastal Olympic Peninsula. This feature and is forecast to drift northeastward to southwestern BC and weaken through the period, while another low digs southeastward from the Gulf of Alaska and intensifies well offshore. Downstream ridging will strengthen in place over the central/ northern High Plains, despite being traversed by several weak vorticity maxima ejecting from the southwest-flow sector of the Northwest cyclone. Meanwhile, a slowly strengthening anticyclone will persist over the Mid-South, lower Mississippi Valley and central/western Gulf Coast States. East of the ridge, MCVs were evident in radar composites over southeastern ND, the southern SD/MN border area, and northwestern IA. With the middle/northern MCVs embedded in faster flow, these should align better as the day progresses. Most synoptic guidance accordingly (and reasonably) yields a coherent, negatively tilted shortwave trough from this phasing, with the perturbation reaching Lower MI and eastern Upper MI by 00Z. At the surface, 11Z analysis showed a cold front offshore from eastern NC, across southern NC and eastern TN, becoming a wavy warm front northwestward over central KY and southern IL to southern/ central MN. A secondary/developing warm front was drawn from central MN east-southeastward over southern WI and southwestern Lower MI, and should become the main warm front through the day in that region. This boundary should move northeastward over central portions of WI, Lake Michigan and western/southern Lower MI. An elongated/complex low-pressure area over the central Dakotas should consolidate through the day and move/redevelop eastward along the warm front to Lake Huron by the end of the period. A weak cold front should move southeastward out of the Dakotas to northern/ central NE and east-central/north-central WY before stalling. ...Upper Mississippi Valley/Great Lakes... Scattered to locally numerous thunderstorms are expected to shift across the area today and tonight, roughly from west to east. A mix of storm modes is expected, including the potential for a few supercells with the full range of severe hazards (gusts, hail, perhaps a tornado or two). Upscale evolution of afternoon convection into a wind-dominant MCS is possible this evening into tonight across portions of WI, Lake Michigan and Lower MI. If confidence increases in a more-specific track and timing for such a complex, a mesoscale concentration of greater probabilities may be needed in a future outlook update. Downstream from the mid/upper ridge, west-northwesterly to westerly flow aloft will orient slightly across the warm front, toward its cool side. However, with slow northward motion of the front, effectively the flow aloft will be front-parallel, helping to support convective growth/maintenance, as low-level theta-e advection and diurnal heating destabilize the convective inflow sector. This will occur amidst a regime of increases in large-scale ascent and vertical shear related to the approaching MCV-related shortwave trough. Forecast soundings show 35-50-kt effective-shear magnitudes and occasional areas of large hodographs with 300-400 J/kg effective SRH, in support of both supercellular and QLCS tornado potential. Meanwhile the area of clouds/precip now over southern MN/IA should move eastward and slowly break up, allowing increasing moisture south of the front, and pockets of favorable diabatic heating. Accordingly, MLCAPE values in the 1500-2000 J/kg range are possible west of Lake Michigan, decreasing with eastward extent into Lower MI where the preconvective air mass has less time to destabilize. Still, warm/moist advection may support surface-based effective- inflow parcels and a residual well-mixed boundary layer well into southern Lower MI tonight, supporting damaging to severe gust potential with any complex after crossing the lake. ...Northern Rockies/Plains... Despite weak height rises aloft, widely scattered thunderstorms are expected to develop this afternoon into early evening -- initially over portions of western/southern MT and perhaps the Black Hills region. In those area, MLCINH will be preferentially reduced by diabatic heating of higher terrain. Seasonally strong mid/upper winds will support both favorable deep-layer shear and fast storm motions onto the northern Great Plains, and near a postfrontal moisture/instability axis over southern/western SD and south- central/southeastern MT. As that occurs, activity should offer severe gusts and hail, with a blend of supercellular and multicellular/bowing modes expected. Surface heating near the moist axis will yield steep low/middle- level lapse rates and a well-mixed boundary layer, beneath about 1000-1500 J/kg peak MLCAPE. Strong veering of winds with height will yield lengthy hodographs and 45-60 kt effective-shear magnitudes, supporting supercell potential. Some upscale clustering and cold-pool growth also may occur from eastern MT into the western Dakotas, with small-scale corridors of severe-gust potential aided by strong ambient flow aloft. ..Edwards/Goss.. 07/04/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1137 AM CDT Sun Jul 03 2022 Valid 031700Z - 041200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE EASTERN GREAT BASIN... The only change with this update was a slight southward expansion of the Critical area into far northwest AZ and southern NV based on the latest surface observations and high-resolution guidance consensus. In addition to the fire-weather concerns described below, RAP forecast soundings show deep inverted-V profiles over parts of central into northeast UT -- supportive of isolated high-based dry thunderstorms and the potential for a lightning-induced ignition or two given receptive fuels. However, the anticipated limited coverage of this activity precludes the introduction of dry thunderstorm highlights. ..Weinman.. 07/03/2022 .PREV DISCUSSION... /ISSUED 0143 AM CDT Sun Jul 03 2022/ ...Synopsis... An upper ridge will shift eastward into the Plains states as a mid-level trough advances toward the Intermountain West today. Surface lee troughing will materialize across the Great Basin, with Elevated to Critical dry and windy conditions developing along the Nevada/Utah during the afternoon hours. Scattered thunderstorms will also develop across the northern Rockies into the Pacific Northwest by afternoon peak heating. While some of these storms may be high-based and potentially dry, overall wetter storms will become more abundant and traverse fuel beds that are marginally receptive to fire spread, precluding dry thunderstorm highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Jul 3 16:40:01 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Jul 3 16:40:01 UTC 2022.

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1121 AM CDT Sun Jul 03 2022 Valid 031630Z - 041200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF MT TO SOUTHWEST ND... ...SUMMARY... The most concentrated corridor of severe storms, including potential for significant severe wind/hail and a few tornadoes, is forecast across parts of Montana into southwest North Dakota through this evening. ...MT to western ND... Primary mid-level low just off the OR coast is embedded within a broader Pacific Coast trough. Multiple waves of ascent are evident downstream of this trough, with the ones most impactful for severe potential across southwest MT this morning and the next across southwest ID. Guidance differs on the degree of intensification of convection with the initial wave, while greater consistency exists on convective evolution emanating out of the latter one. With easterly low-level winds to the north of the effective surface front beneath 35-45 kt mid-level southwesterlies, enlarged and elongated hodographs will be favorable for several supercells, a few of which could become long-tracked. Primary uncertainty is how quickly storm-scale consolidation/upscale growth will occur. Supercell bow-echo evolution does appear probable as convection rides along the surface front given a deeply mixed thermodynamic environment to its south. A forward-propagating MCS is increasingly likely this evening as low-level winds and convergence strengthen across eastern MT. The full spectrum of severe threats is expected with significant large hail most likely from mid-afternoon to early evening, and significant severe wind potential centered on this evening. The tornado threat is more nebulous and convective mode dependent, but will be conditionally favored in a west/east-oriented corridor north of the front. ...Northern/central Great Plains... While most of the region will remain under the influence of low-amplitude mid-level ridging, a broad plume of moderate to large buoyancy is expected at peak heating with relative maxima centered near northwest SD and the KS/NE border. Remnant outflow boundaries, the lee trough over the High Plains, and the warm front across ND and the Red River Valley should all focus scattered to widespread thunderstorms from late afternoon into tonight. Stronger deep-layer shear will generally be confined to the ND/Red River Valley regime within the belt of enhanced mid-level westerlies, suggesting that supercell potential farther south will be tied to mesoscale boundaries with broader multicell clustering tending to dominate. While all severe hazards are possible, wind should become the overall primary threat, especially this evening into tonight as multiple MCSs spread east. ...Carolinas... Scattered thunderstorms are expected across much of the Southeast, but potential for loosely organized multicell clustering is most apparent across NC into parts of SC. The latter will be supported by the presence of differential heating across a southward-sagging cold front and the fringe influence of a trough over QC maintaining 15-20 kt mid-level westerlies. With 2000-2500 J/kg of MLCAPE along the coastal plain, strong to locally severe gusts will be possible in wet microbursts through early evening. ..Grams/Hart.. 07/03/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 AM CDT Sun Jul 03 2022 Valid 031300Z - 041200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN/CENTRAL MONTANA TO PARTS OF WESTERN NORTH DAKOTA... ...SUMMARY... Scattered severe thunderstorm gusts are expected this afternoon through the evening from southern/central Montana to parts of western North Dakota. Isolated large hail also may occur. ...Synopsis... In mid/upper levels, a persistent/high-latitude blocking pattern over western Canada will transition from an omega shape toward a Rex configuration through the period, with slow progress of a basal cyclone now located just offshore from the Pacific Northwest. The associated 500-mb low is forecast to pivot inland over the southwestern WA/northwestern OR area by around 12Z tomorrow, with a trough southward along the OR coastline and offshore from central/southern CA. Several vorticity maxima and shortwaves -- embedded in the cyclone's southern semicircle -- should eject northeastward toward the northern Rockies and through the central/northern High Plains mean ridge. The 11Z surface analysis showed a cold front from near Cape Cod across NJ, northern VA, south-central WV, and northeastern KY, becoming quasistationary over southern parts of IN/IL, then a warm front across western IA, eastern SD and southwestern ND, to a low over southeastern MT. The low should remain over southeastern MT for much of the day before migrating eastward overnight, while the warm front decelerates and perhaps becomes quasistationary to its east over ND, then southeast across southwestern MN. A lee trough will extend from the low across eastern parts of WY and the NE Panhandle. ...MT to western ND... Scattered to numerous thunderstorms are possible, developing in multiple episodes and clusters across southwestern, central, south-central and eastern MT this afternoon into evening. This activity should develop over higher terrain of southern MT, as well as near the boundary, as shots of DCVA/ascent aloft eject over the area and out of the northwestern mid/upper trough. Activity should track along and north of the baroclinic zone, close to an axis of low-level moisture, and with the easterly ambient low-level wind component maximizing storm-relative flow in the inflow layer. This potential will be supported by a corridor of strong veering of flow with height -- supporting 50-60 kt effective-shear magnitudes and enlarged boundary-layer hodographs. Forecast soundings reasonably show steep low/middle-level lapse rates with MLCAPE in the 1500-3000 J/kg range as well. The full spectrum of severe threats is possible, given that sufficient shear and buoyancy will exist for supercells. However, clustering and upscale growth of convection, including bow-echo evolution, are expected. With potential for downward momentum transfer in downdrafts from the faster flow aloft, cold-pool aggregation and rear-inflow-jet development, severe gusts should be the most common effect with this activity overall. ...Northern/central Plains... See SPC mesoscale discussion 1336 for more on the short-term, marginal-hail threat across parts of SD and southwestern MN. Otherwise, isolated to scattered thunderstorms are possible over a broad swath of Nebraska and the Dakotas, east and southeast of the more strongly synoptically influenced MT regime. Specific potential foci for initiation are varied and saddled with mesoscale uncertainties, including: 1. The main synoptic front across ND, where the greatest flow aloft, surface wind backing, hodograph size, and deep shear will be in place for conditional supercell/large-hail and perhaps even tornado potential, but with least confidence in storm location/ coverage due to ridging aloft and recovery concerns around outflow to the south. 2. Outflow/differential-heating boundaries over SD from prior overnight and ongoing convection, and their shaping of theta-e fields. This regime still is being affected by ongoing/elevated activity over the region that itself has at least marginal hail potential. The related MCV -- now apparent in radar animations over northeastern SD -- should be well east of the area by prime destabilization time this afternoon. A choppy field of favorable low-level moisture should develop by mid/late afternoon in a corridor about 100-200 nm wide from southeastern/south-central NE across central SD, beneath midlevel lapse rates steep enough to support 2000-3000 J/kg MLCAPE. 3. The surface low and trailing lee trough, and orographically aided lift over the Black Hills. This regime probably is the most certain for initiation today, ahead of a weak perturbation apparent in moisture-channel imagery over portions of WY/CO. Activity should move into a well-heated/mixed boundary layer and offering a severe- gust threat. However, this area will be under nebulous large-scale forcing (also near the ridge aloft) and weaker bulk shear than farther north. Some activity moving out of the northern part of this regime may persist well into the evening over parts of SD, supported by increasing low-level moisture and the LLJ. ...Carolinas, Hampton Roads... Isolated to scattered thunderstorms are possible along and south of the front today, offering occasional damaging winds that may reach marginal severe levels on an isolated basis. Difluent westerly to northwesterly flow aloft will exist over the region, well southwest of a mid/upper cyclone moving eastward across northeastern QC and Labrador. Following the remnants of T.C. Colin, the airmass over the region will remain richly moist, with surface dew points commonly in the upper 60s to mid 70s F. This, in tandem with diurnal heating, will offset modest midlevel lapse rates enough to support 1000-2000 J/kg MLCAPE. Low/middle-level winds and deep shear will be weak, with multicells the dominant mode and localized, water-loaded downdrafts offering the greatest gust potential, until activity diminishes this evening. ..Edwards/Goss.. 07/03/2022 Read more

No watches are valid as of Sat Jul 2 17:18:02 UTC 2022.

MD 1323 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR PARTS OF NORTHERN VA...EASTERN WV PANHANDLE...MD...DC...DE...NJ...SOUTHEAST PA
Mesoscale Discussion 1323 NWS Storm Prediction Center Norman OK 1216 PM CDT Sat Jul 02 2022 Areas affected...Parts of Northern VA...Eastern WV Panhandle...MD...DC...DE...NJ...Southeast PA Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 021716Z - 021915Z Probability of Watch Issuance...80 percent SUMMARY...An increase in storm coverage and intensity is expected this afternoon, with an attendant risk of locally damaging wind gusts and isolated hail. Severe Thunderstorm Watch issuance is likely. DISCUSSION...Strong heating is underway across much of the Mid Atlantic early this afternoon, though cirrus emanating from convection over WV is limiting insolation across parts of northern VA. Convection is gradually increasing south of the cirrus shield across western VA, while cumulus is gradually increasing across southeast PA, to the north of the VA cirrus shield and south of another cirrus shield across central/eastern PA. Continued destabilization (MLCAPE increasing to near or above 2000 J/kg) will support scattered thunderstorm development later this afternoon, though local minima in storm coverage will be possible where persistent cirrus limits diurnal heating. This region is on the southern fringe of stronger midlevel flow associated with the deep mid/upper-level trough across eastern Canada. Effective shear of 30-40 kt across southeast PA into southern NJ will support the potential for a couple of organized clusters and/or marginal supercells, capable of locally damaging wind gusts and hail. Shear will be somewhat weaker into parts of MD/VA/DE, but still sufficient for a few multicell clusters capable of locally damaging wind gusts (especially where stronger heating occurs), and perhaps some isolated hail. Once a definitive uptick in storm coverage/intensity appears imminent, Severe Thunderstorm Watch issuance is likely across portions of the MCD area. ..Dean/Grams.. 07/02/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OKX...PHI...AKQ...CTP...LWX... LAT...LON 38227926 39747747 40297633 40787487 40867426 39907456 38807527 38237624 37817799 37847894 38227926 Read more

MD 1322 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR NORTHEAST PA INTO PARTS OF SOUTHERN NEW ENGLAND
Mesoscale Discussion 1322 NWS Storm Prediction Center Norman OK 1145 AM CDT Sat Jul 02 2022 Areas affected...Northeast PA into parts of southern New England Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 021645Z - 021845Z Probability of Watch Issuance...80 percent SUMMARY...Storms are expected to increase this afternoon, accompanied by a risk of locally damaging wind gusts and isolated hail. Severe Thunderstorm Watch issuance is likely this afternoon. DISCUSSION...Convection is gradually increasing from northeast PA into southern NY early this afternoon, with some weak midlevel rotation noted with a small cell near Binghamton. Buoyancy is currently modest across the region, but continued diurnal heating/destabilization will support MLCAPE of greater than 1000 J/kg later this afternoon from northeast PA into parts of southern New England. Moderate westerly flow aloft will support effective shear of 40+ kt, sufficient for organized convection. As storm coverage increases with time this afternoon, a couple of organized clusters and/or marginal supercells may develop, with an attendant risk of locally damaging wind gusts and isolated hail. Severe Thunderstorm Watch issuance is probable later this afternoon once a greater coverage of organized storms appears imminent. ..Dean/Grams.. 07/02/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM... LAT...LON 42057573 42797350 42937239 42907190 42547184 41727256 41247392 41167488 41197544 41317597 41467612 41767612 42057573 Read more

MD 1322 CONCERNING SEVERE POTENTIAL...SEVERE THUNDERSTORM WATCH LIKELY FOR NORTHEAST PA INTO PARTS OF SOUTHERN NEW ENGLAND
Mesoscale Discussion 1322 NWS Storm Prediction Center Norman OK 1145 AM CDT Sat Jul 02 2022 Areas affected...Northeast PA into parts of southern New England Concerning...Severe potential...Severe Thunderstorm Watch likely Valid 021645Z - 021845Z Probability of Watch Issuance...80 percent SUMMARY...Storms are expected to increase this afternoon, accompanied by a risk of locally damaging wind gusts and isolated hail. Severe Thunderstorm Watch issuance is likely this afternoon. DISCUSSION...Convection is gradually increasing from northeast PA into southern NY early this afternoon, with some weak midlevel rotation noted with a small cell near Binghamton. Buoyancy is currently modest across the region, but continued diurnal heating/destabilization will support MLCAPE of greater than 1000 J/kg later this afternoon from northeast PA into parts of southern New England. Moderate westerly flow aloft will support effective shear of 40+ kt, sufficient for organized convection. As storm coverage increases with time this afternoon, a couple of organized clusters and/or marginal supercells may develop, with an attendant risk of locally damaging wind gusts and isolated hail. Severe Thunderstorm Watch issuance is probable later this afternoon once a greater coverage of organized storms appears imminent. ..Dean/Grams.. 07/02/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...OKX...ALY...PHI...BGM... LAT...LON 42057573 42797350 42937239 42907190 42547184 41727256 41247392 41167488 41197544 41317597 41467612 41767612 42057573 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1138 AM CDT Sat Jul 02 2022 Valid 021700Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE EASTERN GREAT BASIN... The forecast remains on track, and only minor adjustments were made to the ongoing Critical area based on the latest high-resolution guidance consensus and surface observations. For details, see the previous discussion below. ..Weinman.. 07/02/2022 .PREV DISCUSSION... /ISSUED 0206 AM CDT Sat Jul 02 2022/ ...Synopsis... Upper ridging will persist across the Intermountain West into the Plains as a mid-level trough amplifies along the West Coast today. Surface low development across the Great Basin will encourage Elevated dry and windy conditions across much of Nevada into western Utah, with Critical conditions most likely across eastern Nevada to the Utah border. Across the central Rockies into the Pacific Northwest, scattered thunderstorm development is expected given the presence of monsoonal moisture. A couple dry strikes are possible as far west as Oregon, where storms will also be capable of erratic, potentially severe wind gusts (please see the Day 1 Convective Outlook for more details). However, dry thunderstorm highlights have not been added since fuel receptiveness is expected to be mediocre on a widespread basis. ...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 1117 AM CDT Sat Jul 02 2022 Valid 021630Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PARTS OF THE NORTHEAST AND NORTHERN GREAT PLAINS... ...SUMMARY... Scattered damaging winds are expected across southern New England into the Mid-Atlantic States through early evening. Scattered large hail and severe wind gusts will be possible in the northern Great Plains from late afternoon into tonight. ...Southern New England to Mid-Atlantic States... Isolated to scattered thunderstorms are expected to develop later this afternoon along a northeast/southwest-oriented surface cold front from southwest New England into PA and a lee trough extending south-southwest into western VA. Stronger deep-layer shear will be confined to the southern New England to NY portion amid predominant southwesterly flow. Progressively weaker shear will be noted with southern extent into VA, but this will be compensated by larger buoyancy given greater boundary-layer heating with MLCAPE near 2000 J/kg. The overall setup will likely foster a mix of transient supercells and multicell clusters spreading towards the coast, before weakening during the early evening. Scattered damaging winds will be the primary threat, with isolated severe hail also possible. ...Northern Great Plains... Isolated to scattered thunderstorms are expected to develop during the late afternoon along a modest baroclinic zone and weak surface trough near the MT/ND/SK border area. This initial activity should be higher-based amid MLCAPE of 500-1000 J/kg as surface dew points mix down into the upper 40s to low 50s. While low-level winds will be weak and the region will remain in close proximity to a low-amplitude mid-level ridge, adequate elongation of the mid to upper hodograph should foster a few supercells. Clustering into a small MCS is likely this evening as storms spread towards greater PW emanating northwest from NE into SD and a southerly low-level jet strengthens in advance of the Pacific Northwest shortwave trough. This may yield a persistent, although probably isolated, severe threat into the overnight towards central SD. A mix of large hail and severe wind gusts is anticipated. ...Lower OH Valley to KS/OK... An MCV over northwest MO will drift east to the north of a predominately west/east-oriented baroclinic zone across the Lower OH Valley towards the KS/OK border. While mid-level lapse rates will be modest, robust boundary-layer heating to the south of the composite front/outflow boundaries should foster a corridor of 1500-2500 J/kg MLCAPE. While background vertical shear will be weak, some enhancement of mid-level westerlies attendant to the MCV should be sufficient for a few multicell clusters. Confidence is low in whether a more organized cluster may develop given the myriad of potential boundary-interaction processes and upscale cold-pool aggregation. A broad cat 1/MRGL mainly for the threat of isolated damaging winds remains warranted. ...Interior Northwest... Increasing large-scale ascent owing to approach of a shortwave trough from the northeast Pacific will be favorably timed with the diurnal heating cycle to yield isolated to scattered thunderstorms across central/eastern OR towards the southern ID Panhandle. Forecast soundings suggest that stronger speed shear will generally be confined to the upper portion of the modest buoyancy profile amid 40s to perhaps low 50s surface dew points. A few discrete cells may acquire transient, mid-level updraft rotation, supporting a threat for marginally severe hail. Otherwise, isolated severe wind gusts should be the main hazard given a well-mixed environment. ...Coastal NC... The expected asymmetrical nature of deep convection associated with TC Colin and weak low-level kinematic fields for tornado potential over land suggest that a weak/brief tornado threat appears negligible. ..Grams/Wendt.. 07/02/2022 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Sat Jul 02 2022 Valid 021300Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHEAST AND MID-ATLANTIC...AND OVER PARTS OF THE NORTHERN PLAINS... ...SUMMARY... Isolated to scattered thunderstorms with damaging winds and hail are expected across parts of the Northeast and Mid-Atlantic, and over parts of the northern Plains. ...Synopsis... In mid/upper levels, the synoptic pattern from east-west will remain dominated by: 1. A broad cyclone, initially centered over James Bay, and forecast to pivot across QC to near extreme western Labrador by around 12Z tomorrow. A small shortwave trough -- evident in moisture-channel imagery over southern MB -- is forecast to pivot southeastward over Lake Superior by 00Z, then across southern ON and southern QC to northern New England by the end of the period. 2. Ridging over the Rockies and from the southern Appalachians across north TX to eastern AZ. The Rockies branch of the ridge will move eastward slightly over WY/MT late in the period in response to... 3. A Pacific cyclone initially located well west of Cape Flattery, with troughing southward to near 30N. The 500-mb low should move generally south-southeastward through the period, remaining offshore. However, a series of shortwave troughs/vorticity maxima over its southern semicircle should progress inland and lead to net height falls across the Northwest. At the surface, 11Z analysis showed a cold front from southern QC across northern/western NY, to central OH, becoming quasistationary across south-central IN, southern IL, central MO, and central KS. This front is forecast to move eastward across NY, New England, and parts of eastern PA/NJ through the period, while becoming or remaining quasistationary (under nearly parallel flow aloft) from WV to KS. Another cold front was drawn from far northern ON across western Lake Superior, becoming wavy/quasistationary over southwestern MN, and southeastern ND to northeastern MT. Only mesoscale oscillations are expected to the position of the northern Plains boundary. ...Southern New England to portions of Mid-Atlantic... Scattered thunderstorms are expected to develop in a richly moist environment along/ahead of the front, mainly south of a large area of convective outflow covering New England and NY (that should retreat northward into southern New England/NY today), and near prefrontal troughs and outflow/differential-heating boundaries from ongoing areas of clouds and precip. Scattered damaging wind (in terms of trees/tree limbs/wires, etc.), and isolated severe/50+ kt gusts, are possible from this activity during the afternoon and early evening. Boundary-layer theta-e will be quite favorable, with surface dewpoints commonly in the upper 60s to low 70s F. Areas of either sustained/strong surface heating, or warm advection from such areas beneath somewhat greater antecedent cloud cover, will provide diurnal destabilization. The result thermodynamically should be shallow but well-mixed boundary layer with weakly inhibited (at best) MLCAPE in the 1000-1500 J/kg range, locally/briefly near 2000 J/kg. Though directional shear will be weak, the region will reside beneath the southern rim of stronger mid/upper-level cyclonic flow, contributing to both favorable cloud-layer shear and around 35-45-kt effective-shear magnitudes, in support of some downward momentum transfer and organization of the severe potential beyond typical warm-season pulse downbursts. ... WV/VA Appalachians to KS/northern OK... Farther southwest and west near the front, and outflow boundaries to its south, widely scattered to scattered thunderstorms are possible this afternoon into early evening. Isolated severe gusts/hail will be the main concern, with activity becoming weaker and more isolated from late evening onward. Convection should take the form of variably sized/organized multicellular clusters. Low/middle-level flow and vertical shear will be weak and mainly unidirectional away from boundaries, limiting convective organization to what can be accomplished through low-predictability, localized boundary- interaction processes and temporary upscale cold-pool aggregation. Strong heating and low-level moisture should offset modest midlevel lapse rates to support 1000-2000 J/kg peak/preconvective MLCAPE during mid/late afternoon. ...Northern Plains to western NE... Isolated to scattered thunderstorms are expected to develop this afternoon near and south of the front, with a few supercells possible in the first few hours of the convective cycle, then some upscale expansion into one or two small MCSs over the central/ eastern Dakotas possible before activity diminishes tonight. Severe hail and gusts will be possible. The boundary layer over most of this region is expected to be well-heated/mixed. Greater inflow-layer moisture content (but also somewhat stronger MLCINH) is forecast over northern and eastern parts of the outlook area in closer proximity to evaportanspirative source regions. By contrast, a deeply mixed subcloud layer will characterize much of the High Plains. Steep midlevel lapse rates atop those layers will support MLCAPE peaking around 2000-2500 J/kg over central SD where the greatest juxtaposition of moisture and heating is expected, lessening with northwestward extent into cooler air and southward extent to weaker moisture. Favorably strong upper-level winds and veering with height from low/middle levels will yield enough deep shear for a blend of supercells and organized multicells. The hail threat should peak earlier and farther west, while the wind threat continues eastward and deeper into the evening. ...Inland Pacific Northwest... Isolated to scattered thunderstorms are possible from midafternoon into early evening, offering the potential for gusts/hail near severe limits. Height falls and shots of DCVA/destabilization aloft are expected in strengthening midlevel cyclonic flow, placing large-scale ascent and related steepening of midlevel lapse rates over an area of at least marginal low/middle-level moisture inland. Lower-elevation surface dew points in the 40s to low 50s may lessen somewhat due to mixing through the afternoon. However, surface diurnal heating will help to drive pockets of 500-1200 J/kg MLCAPE where dewpoints remain in the 40s to near 50 F, with a well-mixed subcloud layer. Where not too altered by local orographic effects, generally northeasterly to northerly near-surface winds (northwest of the surface low) will elongate hodographs and strengthen deep shear through strong veering with height, despite modest speeds. This may aid in storm organization as well, with 30-45-kt effective-shear magnitudes possible. ...Coastal southern NC... With tropical-storm-force winds detected offshore, T.S. Colin has been named by NHC while centered near the SC coast, between CHS-MYR. This is a well-sheared system (with respect to the deep-troposphere shear vectors). Accordingly, deepest convection is asymmetrically distributed seaward, and may continue to be, given NHC's forecast of even stronger deep shear than at present. Under those circumstances, and being a small, marginal T.S. not forecast to strengthen much (if at all), at most only a mesobeta-scale area of favorable low-level kinematic fields for tornado potential reasonably will be possible in a downshear (east-northeast) sector. At this time, uncertainty is too great to introduce an unconditional/categorical tornado outlook. If confidence increases in both: 1. Favorably large overland hodographs near Cape Fear and/or Cape Lookout, and 2. Convective trends indicate potential for landfalling supercells in the associated wind field, a small area of tornado probabilities may be necessary in a succeeding outlook update. ..Edwards/Goss.. 07/02/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1134 AM CDT Fri Jul 01 2022 Valid 011700Z - 021200Z The forecast remains on track, and no changes were needed with this update. For details, see the previous discussion below. ..Weinman.. 07/01/2022 .PREV DISCUSSION... /ISSUED 0125 AM CDT Fri Jul 01 2022/ ...Synopsis... A mid-level trough will gradually approach the West Coast as an upper ridge remains in place across the Interior West into the Plains. Under the upper ridge, most locales should experience relatively quiescent fire weather conditions on a widespread basis. The one exception would be portions of central into southern Nevada, where guidance consensus suggests Elevated surface winds/RH will overspread very dry fuels during the afternoon. Otherwise, a couple of dry lightning strikes may accompany scattered thunderstorms developing from a monsoonal environment across the Intermountain West. However, mediocre fuel receptiveness or spareness of dry strikes precludes dry thunderstorm highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Jul 1 16:37:01 UTC 2022.

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1102 AM CDT Fri Jul 01 2022 Valid 011630Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS NORTHEAST WY...SOUTHWEST SD...AND NORTHWEST NE... ...SUMMARY... Scattered severe wind and hail will be possible from about 4 to 10 PM MDT in northeast Wyoming across the Black Hills to the Nebraska Sandhills. ...High Plains... Scattered thunderstorms are expected to develop off the Big Horns to the Sangre de Cristos and spread east across the adjacent High Plains later this afternoon within a plume of upper 40s to mid 50s surface dew points. The greatest potential for organized severe storms will exist across the northern portion of this region from eastern WY into western SD and northwest NE. Here, moderate to strong deep-layer speed shear with height will yield effective bulk values of 40-50 kt and an elongated straight-line hodograph. A few high-based outflow-dominated supercells with mid-level rotation should develop and congeal into a cluster this evening. Initial mix of severe hail and wind transitioning to predominately wind will be the primary threats. A lack of appreciable low-level forcing for ascent this evening in conjunction with a nocturnally stabilizing boundary layer should result in these threats diminishing towards late evening. Farther south to the Raton Mesa, slow-moving thunderstorms may pose a threat for very isolated severe wind gusts and marginally severe wind hail during the late afternoon and evening. ...Lower Great Lakes to the Lower MO Valley... A low-amplitude shortwave impulse near the NE/IA border will shift east along the southern periphery of seasonably moderate to strong mid-level westerlies across the Great Lakes to northern IL/IN/OH. Isolated to scattered thunderstorms will be possible along and just ahead of a cold front sagging southeast across southeast Lower MI through eastern KS later this afternoon. Abundant cloud coverage and weak mid-level lapse rates should temper updraft intensity in the more strongly sheared regime near the Lower Great Lakes. Nevertheless, a few multicell clusters and transient supercell structures may develop with a threat for isolated damaging winds and severe hail through about dusk. ...Mid-Atlantic States... Localized damaging winds and marginally severe hail will be possible through this afternoon as low-level warm theta-e advection-driven convection over the central Appalachians spreads east towards the Mid-Atlantic coast. Poor mid-level lapse rates evident in available 12Z observed soundings and modest deep-layer flow will be limiting factors to a more robust/organized severe threat. See MCD 1314 for further short-term discussion. Additional thunderstorms may spread towards the region tonight from the Lower Great Lakes/Upper OH Valley, but should largely be in a decaying state. ...Northern ME... Pronounced differential diabatic heating and weak low-level convergence may aid in isolated thunderstorms near the Saint Lawrence Valley into southeast QC later this afternoon. Morning guidance suggests a nadir in low-level moisture will be present across parts of western New England, but adequate moisture may still hold across northern ME. This may yield a corridor of weak buoyancy amid poor mid-level lapse rates. The most favorable factor will be effective bulk shear of 40-50 kts, which would conditionally support a supercell or two, but confidence is low. ..Grams/Wendt.. 07/01/2022 Read more

MD 1314 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR WESTERN/NORTHERN MD...EASTERN WV...SOUTHERN PA...NORTHERN VA...NORTHERN DE...DC
Mesoscale Discussion 1314 NWS Storm Prediction Center Norman OK 1059 AM CDT Fri Jul 01 2022 Areas affected...Western/northern MD...Eastern WV...Southern PA...Northern VA...Northern DE...DC Concerning...Severe potential...Watch unlikely Valid 011559Z - 011830Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms are expected to increase in coverage and intensity this afternoon, with a threat of isolated damaging wind gusts and possibly some hail. DISCUSSION...Convection has gradually been increasing late this morning across southern PA into eastern WV, within a zone of richer moisture in the 925-850 mb layer depicted in the 12Z PIT sounding and recent objective mesoanalyses. Diurnal heating and continued low-level moisture transport will support an increase in thunderstorm coverage and intensity this afternoon, as convection gradually spreads eastward toward the I-95 corridor. MLCAPE increasing above 2000 J/kg will support vigorous updrafts, though marginal effective shear (generally in the 20-30 kt range) will limit storm organization to some extent. Steepening low-level lapse rates will support a threat of locally damaging wind gusts this afternoon, and isolated hail will also be possible with the strongest cells. With storm organization expected to remain rather limited, watch issuance is considered unlikely at this time. ..Dean/Grams.. 07/01/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...CTP...LWX...PBZ...RLX... LAT...LON 40318004 40797727 40687595 40387568 39597557 39257544 38777663 38507779 38257883 38347938 38657995 39108031 39768044 40318004 Read more