Severe Storms

MD 1597 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHERN APPALACHIANS INTO THE MID-ATLANTIC REGION
Mesoscale Discussion 1597 NWS Storm Prediction Center Norman OK 1253 PM CDT Wed Jul 27 2022 Areas affected...Southern Appalachians into the Mid-Atlantic Region Concerning...Severe potential...Watch unlikely Valid 271753Z - 272000Z Probability of Watch Issuance...5 percent SUMMARY...Thunderstorms are gradually intensifying across the southern Appalachians, and will likely pose at least an isolated damaging wind risk this afternoon. A watch is not anticipated. DISCUSSION...GOES and regional reflectivity imagery has shown a slow percolation of shallow convection across the southern Appalachians and along an east-ward propagating outflow boundary over the past 1-2 hours. Recent data (over the past 10-20 minutes) has shown a gradual uptick in convective intensity, including cooling cloud-top temperatures, rising echo tops, and increasing lightning counts. This is largely being driven by diurnal heating of a moist boundary layer across the southern Appalachians and into the Mid-Atlantic region. Recent ACARs soundings show this gradual destabilization, and latest MLCAPE estimates have increased to 1500-2000 J/kg. Further destabilization is possible where cloud cover is more broken and temperatures can break out of the upper 80s, which should maintain the recent intensification trend. Regional VWPs, supplemented by forecast soundings, are generally sampling 20-35 knot zonal mid-level winds with modest (around 20 knots) deep-layer shear. Wind (and shear) magnitudes generally increase with northward extent away from the better buoyancy, but there should be sufficient overlap of favorable thermodynamics/kinematics to support loosely organized clusters and perhaps semi-cohesive outflows. In general, the weak kinematic environment will limit the severe weather threat and minimize the potential for a watch, but isolated damaging winds appear probable through the afternoon hours. ..Moore/Guyer.. 07/27/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...MHX...LWX...RAH...RNK...RLX...GSP...MRX... JKL... LAT...LON 35827742 35557872 35598053 35288260 35528341 36088351 37888221 38698066 38807810 38257713 37157680 36317682 35827742 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1215 PM CDT Wed Jul 27 2022 Valid 281200Z - 291200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST STATES...AND FROM THE OZARK PLATEAU INTO THE TN/OH VALLEYS... ...SUMMARY... Isolated severe thunderstorm gusts and hail are possible over portions of the Northeast, as well as from the Ozarks eastward across the Tennessee and Ohio Valleys. ...Synopsis... A mature mid-latitude cyclone is forecast to begin the period centered over north-central Ontario before drifting slightly southeastward throughout the period. Shortwave troughs will continue to rotate around this cyclone, including one that is expected to progress from the Upper Great Lakes eastward through southern Ontario into the Northeast. At the surface, an outflow-reinforced front will likely extend from a low over northwest TX northeastward into the Mid MS Valley. This front then transitions to a more traditional, progressive cold front, stretching from the Mid MS Valley northeastward into far western NY and then back northward to a triple point near the central Ontario/Quebec border intersection. This front is expected to move eastward/southeastward through the Northeast while the portion of the front back west over the Plains remains largely stationary. ...Northeast... The air mass preceding the front across the Northeast will likely be characterized by dewpoints in the mid to upper 60s and modest buoyancy, and thunderstorm development is anticipated along and ahead of the front as it moves through the region. A belt of enhanced mid-level flow is expected to move into the region on Thursday as well, although the strongest flow will likely lag behind the cold front. Even so, enough mid-level flow should be present to support 30 to 40 kt of deep-layer vertical shear. These environmental conditions will support the potential for a few more organized updrafts capable of damaging wind gusts and/or isolated hail. Southerly low-level flow through the Champlain Valley vicinity eastward across NH and western/central MA could result in enough low-level veering for a brief tornado or two, particularly with any discrete storms ahead of the primary line. ...Ozark Plateau...Mid MS Valley...TN/OH Valley... Strong diurnal heating in the presence of abundant low-level moisture is expected to result in diurnal destabilization in the vicinity of the front stretch from the Ozarks into the OH Valley. Convergence along the front coupled with modest large-scale ascent attendant to a weak (potentially stronger if convective enhancement materializes) should result in numerous thunderstorms across the region. Vertical shear will be weak, with a mostly multicellular mode anticipated, but a few damaging water-loaded downbursts are possible. Additionally, despite relatively poor lapse rates, the overall strength of the instability could still result in isolated instances of hail. ..Mosier.. 07/27/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Jul 27 2022 Valid 271630Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL HIGH PLAINS... ...SUMMARY... Large hail, severe wind gusts, and a tornado or two will be possible late this afternoon and evening across the central High Plains. Isolated wind damage will be possible this afternoon from the Ozarks to the Mid-Atlantic. ...Central High Plains late this afternoon/evening... A spatially shrinking thunderstorm cluster across southwest Nebraska should further weaken/diminish as it parallels the elevated portion of a northwest/southeast-oriented frontal zone across the region. Otherwise, given visible/surface observational trends, latest thinking remains that this front and related low-level upslope trajectories/differential heating will influence at least widely scattered thunderstorm development by mid/late afternoon, initially across far eastern Wyoming, far northeast Colorado, the Nebraska Panhandle, and perhaps as far north as the Black Hills vicinity. Upper 50s/low 60s F surface dewpoints will support MLCAPE values of 1500-2000 J/kg by mid/late afternoon. While mid-level lapse rates will not be particularly steep, the moderate buoyancy and relatively long hodographs (effective bulk shear near 40 kt) will favor a few south/southeastward-moving supercells by late afternoon. Occasional large hail and severe outflow gusts will be the main threats, though a tornado or two may also occur with the more persistent supercells. There is the potential that one or more southeastward-moving thunderstorm clusters could evolve this evening, particularly across far southwest Nebraska/northwest Kansas with severe-caliber wind potential. ...Ozarks to the Mid-Atlantic this afternoon/evening... An effective frontal zone remains and continues to be reinforced from the Ozarks to the Mid-Atlantic. This boundary and differential heating and possible weak MCV influences will help focus additional thunderstorm development this afternoon. Strong mid-level winds/vertical shear will tend to remain to the cool side of the front, with weaker wind profiles in the unstable warm sector to the south, with one exception being the windward side of the central Appalachians where low/mid-level winds are a bit stronger and could support a few transient supercells. More broadly, a diurnal steepening of low-level lapse rates with daytime heating and cloud breaks, in combination with moderate to locally strong buoyancy, will support some threat for isolated wind damage with downbursts in multicell clusters this afternoon into evening. ...Midwest/Great Lakes... Near a secondary southeastward-moving front, mid-level winds will be relatively stronger with a relatively moist air mass remaining in place. However, the influence of clouds and some lingering morning convection continue to cast uncertainty on the potential for thunderstorms capable wind damage within a zone spanning northern portions of Illinois/Indiana into Ohio. ..Guyer/Moore.. 07/27/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1023 AM CDT Wed Jul 27 2022 Valid 271700Z - 281200Z The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 07/27/2022 .PREV DISCUSSION... /ISSUED 0159 AM CDT Wed Jul 27 2022/ ...Synopsis... An amplified large-scale ridge will persist over the northwestern CONUS, while a belt of moderate northwesterly midlevel flow overspreads the northern Rockies. This large-scale pattern will result in an overlap of hot/dry boundary-layer conditions (10-15 percent RH) and breezy northerly surface winds near 15 mph over parts of southeast OR, southwest ID, and northern NV. Given highly receptive fuels over these areas, elevated fire-weather conditions will be possible during the afternoon. In addition, diurnal heating coupled with adequate midlevel moisture over the northern Rockies will support isolated high-based thunderstorms during the afternoon -- aided by a subtle midlevel impulse crossing the area. Any storms that can develop and overspread critically dry fuels and the deeply-mixed boundary layer could lead to isolated lightning-induced ignitions. Farther west along the Cascades in northern CA into southern OR, additional high-based thunderstorm development will be possible as upslope flow strengthens amid modest buoyancy. While storm coverage is expected to be limited, even isolated strikes over this area could result in ignitions owing to very dry fuels. Over the southern Plains, breezy southerly surface winds and 15-20 percent minimum RH could favor locally elevated conditions during the afternoon. However, these conditions look too marginal/localized for highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Jul 26 17:52:01 UTC 2022.

MD 1593 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTHERN APPALACHIANS INTO CENTRAL VIRGINIA/NORTH CAROLINA
Mesoscale Discussion 1593 NWS Storm Prediction Center Norman OK 1232 PM CDT Tue Jul 26 2022 Areas affected...Southern Appalachians into central Virginia/North Carolina Concerning...Severe potential...Watch unlikely Valid 261732Z - 261930Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms will continue to gradually intensify through the afternoon hours and may pose a damaging wind threat. A watch is not expected given the weak kinematic environment. DISCUSSION...Over the past hour, new thunderstorm development and/or intensification of ongoing convection has been noted over the KY/TN border along an outflow boundary from a swath of early-morning elevated thunderstorms/stratiform rain. To the east across NC, low-level parcels are quickly reaching their convective temperatures as surface temps warm into the upper 80s and low 90s, fostering scattered, poorly-organized thunderstorm development. Convection in both regions have exhibited signs of steady intensification as destabilization continues. Recent mesoanalysis estimates suggest MLCAPE has increased to nearly 2000-2500 J/kg across the region, and the rapid onset of convective initiation in the absence of strong low-level forcing hints at minimal inhibition. The general expectation is that the recent intensification trend will continue through the afternoon hours across the southern Appalachians and VA/NC. ACARs soundings and VWP observations over the past couple of hours have sampled modest zonal winds throughout the column, which is supporting meager deep-layer shear (on the order of 20 knots by most estimates). This limiting factor will modulate the degree of storm organization and the overall severe risk. However, the broken line of storms developing over the southern Appalachians may propagate eastward with a semi-cohesive outflow capable of sporadic damaging winds given the mean wind vector orthogonal to the developing line. More isolated to scattered cells/multicells ahead of this line may also see periodic intensification given the favorable thermodynamic environment, and may briefly pose a damaging wind threat. Regardless, the severe threat is expected to remain sufficiently low to negate the need for a watch. ..Moore/Guyer.. 07/26/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...MHX...LWX...RAH...RNK...CAE...GSP...MRX... LAT...LON 36538352 37458067 37797894 37697708 37147678 36327687 35327772 35017971 35038149 35368340 36068406 36538352 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1211 PM CDT Tue Jul 26 2022 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE OZARK PLATEAU EASTWARD INTO THE MID-ATLANTIC STATES...AND ALSO ACROSS THE CENTRAL HIGH PLAINS... ...SUMMARY... Isolated severe thunderstorms will be possible Wednesday from parts of Missouri and Arkansas eastward into the Ohio and Tennessee Valleys and Mid Atlantic, with damaging wind gusts and isolated hail possible. Isolated severe storms over the central High Plains may produce severe hail and damaging gusts during the afternoon and evening. ...Synopsis... A mature mid-latitude cyclone is forecast to gradually shift eastward into more of western Ontario on Wednesday. As it does, several shortwave troughs will rotate through its base, moving over the northern Plains and Upper Midwest. The surface pattern early Wednesday morning will feature a stationary front extended from the central Plains eastward across the Mid MS Valley and OH Valley into the Mid-Atlantic. Additionally, a surface low associated with the mid-latitude cyclone will likely be centered over northern Ontario, with a cold front extending southwestward into the central Plains. ...Ozark Plateau to the Mid Atlantic... Showers and thunderstorms will likely be ongoing Wednesday morning within the warm-air advection regime over the Lower/Middle OH Valley, to the north of the stationary boundary mentioned in the synopsis. This morning activity will likely diminish during the morning hours, coincident with weakening low-level flow. Outflow associated with these storms could augment the stationary boundary, with this boundary then acting as an effective cold front as it moves eastward into the Mid-Atlantic during the afternoon. Additional thunderstorms are anticipated during the afternoon, both along the outflow mentioned above as well as in the vicinity of the stationary boundary farther west into the Ozark Plateau and Mid MS Valley. The airmass across the entire region will be moist, buoyant, and moderately sheared. The stronger flow aloft will likely be displaced north of the boundary and associated thunderstorm development. Even so, there should be enough overlap between the buoyancy and shear for a few stronger storms. A multicellular mode is favored, but some bowing line segments capable of isolated damaging wind gusts are possible, particularly in the Mid MS Valley. ...Central High Plains... Thunderstorms will likely be ongoing in the vicinity of the NE Panhandle early Wednesday morning, supported by warm-air advection and steep mid-level lapse rates. Potential exists for some organization of these storms, which could result in an early to mid morning severe threat from the NE Panhandle into central NE. Probability of this scenario is low, but the outlook area was expanded slightly eastward to account for this possibility. Additional thunderstorm development is anticipated during the afternoon as low-level moisture advection, diurnal heating, and an approaching cold front combine to create a favorable environment for late-afternoon storm initiation. Northwesterly flow aloft atop low-level southeasterly flow will result in moderate vertical shear, and the potential for a supercell or two. Large hail and strong wind gusts are the main severe threat, but a brief tornado is also possible. ..Mosier.. 07/26/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Tue Jul 26 2022 Valid 261630Z - 271200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL PLAINS/UPPER MIDWEST AND OZARKS TO NORTH CAROLINA/VIRGINIA... ...SUMMARY... Isolated large hail and damaging winds will be possible from northeast Colorado to southern Minnesota later this afternoon/evening, and isolated damaging winds will be possible this afternoon from southern Missouri eastward to parts of Virginia and North Carolina. ...Central Plains/Upper Midwest this afternoon/evening... A cold front will move south-southeastward across these regions through evening while being influenced by a moderately strong cyclonic belt of westerlies. Further thunderstorm development is expected especially into late afternoon/evening near the front across the Upper Midwest including southern Minnesota, and along/north of the front across the central High Plains including parts of Nebraska/Kansas and northeast Colorado. Moderate buoyancy and largely straight hodographs with effective bulk shear of 30-40 kt will support the development of a few supercells capable of producing isolated large hail and/or severe-caliber wind gusts. The severe risk is expected to remain relatively isolated/marginal overall, but a somewhat higher concentration/probability for severe storms may exist across parts of Nebraska. Observational/short-term guidance trends will be reevaluated into mid-afternoon for a potential Slight Risk upgrade. ...Southern Missouri to Virginia/North Carolina this afternoon... Little if any changes appear to be warranted for this severe-weather scenario. A surface front will remain quasi-stationary from southern Kansas eastward across southern Missouri into Kentucky/West Virginia/Virginia, with clouds/precipitation remaining persistent in areas near/north of the front. South of the front and ongoing precipitation, moderate to locally strong buoyancy and a diurnal steepening of low-level lapse rates will support some potential for downburst-related isolated wind damage. ..Guyer/Moore.. 07/26/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1041 AM CDT Tue Jul 26 2022 Valid 261700Z - 271200Z Isolated dry thunderstorm highlights have been added for portions of northern California into southwest Oregon. Latest objective analysis showed a small mid-level impulse traversing the California coastline while moving northward. Mainly showers have accompanied this impulse in central California, though a couple of lightning flashes were also noted. This impulse is expected to continue moving northward through the day and approach a plume of marginal buoyancy currently off of the southwest Oregon coastline. The approach of this impulse, in tandem with diurnal heating and terrain-induced lift may support the development of a dry thunderstorm or two across far northern parts of the Sacramento Valley into the southern Cascades (especially the windward side). While confidence in 10+ percent coverage remains quite low, the very high receptiveness of fuels to wildfire spread suggests that low-probability but high-impact wildfire-start potential exists this afternoon and evening. Otherwise, the previous forecast (see below) remains on track, with only slight changes made to the Elevated highlights in the southern Plains to reflect the latest guidance consensus. ..Squitieri.. 07/26/2022 .PREV DISCUSSION... /ISSUED 0156 AM CDT Tue Jul 26 2022/ ...Synopsis... Elevated fire-weather conditions are expected over parts of northwest OK this afternoon, as 15 mph sustained southerly surface winds (with higher gusts) develop in response to a weak surface low over the area. The breezy surface winds, coupled with 20 percent minimum RH and highly receptive fuels warrant the Elevated highlights -- especially given ongoing fires over the area. Over the Intermountain West/Northern Great Basin, a belt of moderate northwesterly midlevel flow and hot/dry boundary-layer conditions could support spotty elevated fire-weather conditions during the afternoon. This will especially be the case from southeast OR eastward across southern ID into southwest WY. However, these conditions look too localized/marginal for highlights. In addition, an isolated high-based thunderstorm or two cannot be ruled out along the Cascades from far north-central CA into south-central OR. If this activity can develop, an isolated lightning-induced ignition would be possible owing to very dry fuels across the area. With that said, confidence in the development of any more than a storm or two is too low for dry thunderstorm highlights at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

WW 0503 Status Updates
STATUS FOR WATCH 0503 HAS NOT BEEN ISSUED YET Read more

WW 503 SEVERE TSTM DC DE MD NJ PA VA WV CW 251745Z - 260200Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 503 NWS Storm Prediction Center Norman OK 145 PM EDT Mon Jul 25 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Delaware Maryland New Jersey Southeast Pennsylvania Virginia Far Eastern West Virginia Coastal Waters * Effective this Monday afternoon and evening from 145 PM until 1000 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph likely SUMMARY...Thunderstorms will further develop and intensify initially near/just of the mountains, and subsequently spread eastward toward the I-95 corridor through late afternoon and early evening. Damaging winds are the primary hazard. The severe thunderstorm watch area is approximately along and 110 statute miles east and west of a line from 5 miles east northeast of Trenton NJ to 40 miles west of Richmond VA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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 502... AVIATION...A few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 27025. ...Guyer Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1214 PM CDT Mon Jul 25 2022 Valid 261200Z - 271200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHEASTERN MISSOURI EASTWARD TO PORTIONS OF THE VIRGINIA AND NORTH CAROLINA COASTS... ...SUMMARY... Isolated severe thunderstorms will be possible Tuesday from the mid-Atlantic region west to portions of the Ohio and Tennessee Valley region. A few damaging wind gusts locally will be the primary severe hazard. ...Synopsis... South of a pair of central and eastern Canada upper lows, moderate cyclonic flow will prevail Tuesday from the north-central U.S. eastward across the Northeast. Farther south, weak flow aloft will prevail. At the surface, a baroclinic zone will remain largely in place from the Mid-Atlantic region westward to the central High Plains through the period. ...Mid Mississippi Valley region eastward to the Virginia and North Carolina Coastal area... A nearly stationary surface front is forecast to remain in place from Virginia to Missouri on Tuesday. Showers and thunderstorms will likely be ongoing in the vicinity of this boundary at the start of the period, from the Mid-Mississippi to Mid-Ohio Valleys, where a stronger gust or two cannot be ruled out. During the day, heating/destabilization along the boundary in areas less affected by ongoing precipitation/cloud cover will yield an expansion in convective coverage, with storms eventually developing/spreading eastward with time to cover much of the MRGL risk area. With moderate/roughly unidirectional westerly flow aloft progged atop the front, a few stronger wind gusts appear likely -- particularly if storms can evolve locally into an eastward-moving cluster or two. At this time, confidence is too low to narrow down an area of possibly greater severe potential/coverage, so will maintain broad MRGL risk from southeastern Missouri eastward to coastal Virginia and North Carolina. ..Goss.. 07/25/2022 Read more

MD 1590 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTH CAROLINA INTO SOUTHERN VIRGINIA
Mesoscale Discussion 1590 NWS Storm Prediction Center Norman OK 1216 PM CDT Mon Jul 25 2022 Areas affected...North Carolina into southern Virginia Concerning...Severe potential...Watch unlikely Valid 251716Z - 251915Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms may intensify and support isolated damaging winds through the afternoon hours across western to central North Carolina and southern Virginia. Watch issuance is currently not anticipated. DISCUSSION...A broad cluster of thunderstorms has developed within the southern Appalachians and along a lee trough axis across western VA/NV over the past couple of hours. This activity has largely remained disorganized, likely due to weak flow observed in the KFCX, KMRX, and KRAX VWPs. However, increasing cloud-top heights and cooling cloud-top temperatures in a few cells hint at gradual intensification over the past 30-60 minutes. This trend will continue through the afternoon as warming temperatures, coupled with dewpoints in the low to mid 70s, boosts MLCAPE values to near 2000-2500 J/kg with minimal inhibition. A few strong to severe storms are possible and may exhibit periods of semi-organized outflow. However, deep-layer flow is expected to remain meager across the region as the synoptic mid-level wave passes well to the north. This will limit the potential for widespread organized severe weather and likely mitigates the need for a watch, though isolated damaging wind gusts will be possible through the afternoon. ..Moore/Guyer.. 07/25/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AKQ...RAH...RNK...GSP...MRX... LAT...LON 35868317 36658153 37188073 37368009 37247925 36947824 36377821 35567854 35117955 35118119 35158233 35388312 35868317 Read more

WW 0502 Status Updates
STATUS FOR WATCH 0502 HAS NOT BEEN ISSUED YET Read more

WW 502 SEVERE TSTM CT MA ME NH NJ NY PA RI CW 251705Z - 260000Z
0- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 502 NWS Storm Prediction Center Norman OK 105 PM EDT Mon Jul 25 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Connecticut Massachusetts Maine New Hampshire Northern New Jersey Southern New York Far Northeast Pennsylvania Rhode Island Coastal Waters * Effective this Monday afternoon and evening from 105 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph likely A tornado or two possible SUMMARY...Multiple corridors of strong to severe thunderstorms are expected across the region this afternoon through early evening along/ahead of a cold front. This scenario is supported by moderately strong winds through a deep layer a moist/moderately unstable air mass, although some lingering cloud cover may temper destabilization somewhat. The severe thunderstorm watch area is approximately along and 70 statute miles east and west of a line from 30 miles west southwest of Bridgeport CT to 85 miles north northeast of Bangor ME. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2). 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 500. Mean storm motion vector 27030. ...Guyer Read more

MD 1589 CONCERNING SEVERE POTENTIAL...WATCH LIKELY FOR VIRGINIA INTO SOUTHEAST PENNSYLVANIA AND SOUTHERN NEW JERSEY
Mesoscale Discussion 1589 NWS Storm Prediction Center Norman OK 1202 PM CDT Mon Jul 25 2022 Areas affected...Virginia into southeast Pennsylvania and southern New Jersey Concerning...Severe potential...Watch likely Valid 251702Z - 251900Z Probability of Watch Issuance...80 percent SUMMARY...Thunderstorms will continue to increase in coverage from central Virginia into southeast Pennsylvania and southern New Jersey through the afternoon as a cold front approaches the Mid-Atlantic region. Thunderstorms will primarily pose a damaging wind threat, and will likely require a watch. DISCUSSION...Latest GOES visible imagery reveals several convective cells developing along the WV/VA/MD border ahead of an approaching cold front and along a weak lee trough axis. Increasing lightning counts and cloud top heights have been noted with some of the deeper convection over the past 20 minutes, indicative of gradual intensification. These storms are forecast to migrate east into central/northern VA during the 17-19 UTC period, and will likely undergo further organization/intensification as they encounter an air mass featuring seasonally rich low-level moisture (which is supporting upwards of 1500-2000 J/kg MLCAPE) and around 20-30 knots of effective bulk shear (as estimated from recent ACARs soundings from the Washington D.C. area and recent KLWX and KDIX VWP obs). Furthermore, temperatures rising into the low 90s will support steepening boundary-layer lapse rates, and winds near the top of the boundary layer are forecast to increase to 25-35 mph by mid/late afternoon, both of which should foster the potential for damaging thunderstorm winds. A watch will likely be needed in the next 30-90 minutes as thunderstorm coverage and intensity slowly increase. ..Moore/Guyer.. 07/25/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...CTP...LWX...RNK... LAT...LON 37837661 37237799 37377920 37757965 38367938 39077873 39667761 40127593 40067499 39577446 38397556 37837661 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Mon Jul 25 2022 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NEW ENGLAND TO THE MID-ATLANTIC STATES... ...SUMMARY... Scattered strong/severe thunderstorm wind gusts are expected across parts of the Mid-Atlantic States and New England this afternoon through early evening. ...New England/Mid-Atlantic States... The region will be influenced by a low-amplitude shortwave trough and speed max today, with moderately strong mid/high-level winds noted in regional 12z observed soundings as far south as roughly the Pennsylvania/Maryland border vicinity. Scattered thunderstorms are expected to increase in coverage and intensity this afternoon along and ahead of a surface cold front including near a pre-frontal trough. Pre-frontal showers and residual cloud cover persist particularly from New Jersey/eastern Pennsylvania into southern New England, but gradual destabilization and an erosion of boundary layer inhibition is occurring especially across southern New England late this morning and midday. Even with lingering residual cloud cover, the corridor of strongest destabilization this afternoon should largely parallel the I-95 general vicinity from Virginia into southern New England, where MLCAPE may reach/exceed 2000-2500 J/kg. Effective shear magnitudes will generally range from a supercell-supportive 40-50 kt over New England to around 25-30 kt southwestward into Virginia/eastern West Virginia, where a deeply mixed boundary layer will nonetheless support pulse/multicell-related wind gust potential. Severe/locally damaging wind gusts will be the most common severe risk (almost exclusively) overall, but a tornado cannot be ruled particularly across southern New England where deep-layer shear and low-level shear/SRH will be stronger. ...Middle Mississippi Valley/Ozarks... A few strong/locally severe thunderstorms could occur this afternoon within a moist/unstable environment near the front across southern Missouri, but will not adjust/reintroduce severe probabilities at this time given lingering forecast uncertainties and relatively low/isolated perceived severe potential overall. A somewhat higher probability/coverage of storms is expected tonight and farther north from northeast Kansas across northern Missouri into western/south-central Illinois. This will be as a southwesterly low-level jet intensifies and warm advection/isentropic ascent increases coincident with the elevated frontal surface. A few organized and potentially severe storms may occur, particularly early in the convective cycle before a more front-parallel linear configuration evolves. That said, potential upscale growth into an MCS could eventually occur. ...Central/northern High Plains... A conditional and/or fairly localized severe potential (hail/wind) is evident in this region this afternoon into this evening, with a deeply mixed diurnal boundary layer, steep low/middle-level lapse rates, and pockets of favorable/residual moisture all expected to support a plume of 1500-2000 J/kg MLCAPE from parts of western South Dakota into western Nebraska. Have introduced low severe probabilities for parts of this region where a few severe storms appear a bit more probable. Any convection that does develop will be in an environment of modest-magnitude but strongly veering low-level winds with height, leading to long hodographs and around 40-50 kt effective-shear magnitudes. ..Guyer/Moore.. 07/25/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1016 AM CDT Mon Jul 25 2022 Valid 251700Z - 261200Z ...NO CRITICAL AREAS... The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 07/25/2022 .PREV DISCUSSION... /ISSUED 0152 AM CDT Mon Jul 25 2022/ ...Synopsis... A belt of enhanced west-northwesterly midlevel flow will remain in place across the northern CONUS, while a compact shortwave trough crosses the northern Rockies and adjacent High Plains. As moderate midlevel flow accompanying the shortwave trough overspreads a diurnally deepening boundary layer over southern WY, a corridor of 15 mph sustained westerly surface winds will be possible amid 10-15 percent RH. However, recent light to moderate rainfall over the area and only marginally elevated conditions cast uncertainty on the overall fire-weather threat -- precluding Elevated highlights at this time. Farther south over parts of the southern Plains, breezy southerly surface winds will develop in response to a weak surface low near the OK Panhandle. The breezy surface winds, coupled with 20-25 percent minimum RH, could result in locally elevated conditions where fuels are receptive to wildfire spread. With that said, these conditions look too marginal/spotty for highlights. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Jul 24 18:00:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sun Jul 24 2022 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF NEW ENGLAND INTO THE MID-ATLANTIC REGION... ...SUMMARY... Scattered severe thunderstorms will be possible Monday from portions of New England to the Mid-Atlantic region. Damaging gusts will be the primary severe hazard. Isolated severe storms will also be possible over portions of the northern and central High Plains vicinity. ...Synopsis... Weak flow aloft will prevail over the southern half of the U.S. Monday, while a belt of enhanced/cyclonic flow resides over the northern third of the country south of a pair of Canadian upper cyclones. At the surface, an arcing front will shift eastward across the Northeast, southward across the Ohio Valley and central U.S., and then nearly stationary/backed into the High Plains through the period. ...New England to the Mid-Atlantic region, and westward into the Mid South... As a cold front advances eastward into/across New England and southeastward across the Ohio Valley during the day Monday, thunderstorms -- likely ongoing locally at the start of the period -- are expected to increase in coverage and intensity through late morning/early afternoon. The increase -- fueled by a moist/destabilizing pre-frontal environment -- will be aided by a belt of strong deep-layer southwesterly flow spreading across the area in tandem with short-wave troughing sweeping across the St. Lawrence Valley through the day. With a somewhat-more-southerly component to the low-level flow, veering and increasing with height to southwesterly, shear will favor organized storms. While bands of convection should become the primary storm mode, updraft rotation in stronger cells may support risk for a tornado. Otherwise, damaging wind gusts will likely be the primary severe risk, along with some hail potential. Storms will spread eastward with time in tandem with the cold-frontal advance, gradually moving offshore but lingering longest over southeastern New England and the mid-Atlantic region. Farther west along the front, into parts of Kentucky and Tennessee, severe risk should remain more limited, due to weaker flow aloft. Still, storms developing along the front will likely be accompanied by local risk for damaging wind gusts and/or hail. ...Eastern Wyoming into western South Dakota and the Nebraska Panhandle... A belt of cyclonic flow aloft will remain across the north-central U.S. Monday, on the southern fringe of a pair of central Canada lows. As weak disturbances move southeastward across the northern and central Plains vicinity, a frontal wave is forecast to be maintained over the Nebraska Panhandle vicinity, along front progged to remain draped from northwest to southeast from the northern High Plains. Diurnal heating/destabilization near and ahead of this front/low, along with focused ascent aided by the passage of the aforementioned disturbances aloft will likely prove sufficient for isolated afternoon storm development. With 25 to 35 kt west-northwesterly flow aloft atop low-level southeasterlies near and just east of the front, a few stronger storms may organize, and possibly grow upscale into a small cluster. Local risk for a couple of damaging wind gusts and/or hail warrants maintenance of MRGL risk across this area. ..Goss.. 07/24/2022 Read more