Severe Storms

WW 0507 Status Updates
STATUS FOR WATCH 0507 HAS NOT BEEN ISSUED YET Read more

WW 507 SEVERE TSTM MD VA CW 291730Z - 300000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 507 NWS Storm Prediction Center Norman OK 130 PM EDT Fri Jul 29 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Southern Maryland Southern and eastern Virginia Coastal Waters * Effective this Friday afternoon and evening from 130 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph likely SUMMARY...Initial cluster in central Virginia should pose the primary threat for damaging winds as it spreads east towards the southern Delmarva Peninsula. An additional cluster may form across southwest Virginia and spread towards southeast Virginia as well. The severe thunderstorm watch area is approximately along and 75 statute miles east and west of a line from 15 miles northeast of Patuxent River MD to 25 miles west of South Hill VA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU7). 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 60 knots. A few cumulonimbi with maximum tops to 600. Mean storm motion vector 26030. ...Grams Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1212 PM CDT Fri Jul 29 2022 Valid 301200Z - 311200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms associated with strong winds will be possible on Saturday afternoon from parts of Oklahoma and far northeast Texas into Arkansas. ...Synopsis and Discussion... Expansive subtropical ridging is forecast to extend across the Southeast and southern Plains early Saturday morning, with another upper ridge centered near the northern CA/NV and covering much of the western CONUS. This dominance of upper ridging will lead to predominantly weak flow aloft across the majority of the CONUS. The only exceptions are early in the period across the Northeast, before the shortwave trough extended over the region moves eastward, and over the northern High Plains/northern Plains during from late Saturday afternoon into Sunday morning. This second area will be coincident with a modest shortwave trough moving through the Canadian Prairie Provinces and adjacent northern High Plains/northern Plains. Surface pattern is expected to feature a large ridge centered over the OH Valley, and modest lee troughing across the High Plains. A frontal zone will exist between the more continental air associated with the ridging and moist air mass across much of the southern Plains and Southeast. This frontal zone will be fairly broad, with some more defined portions possible due to potential augmentation via thunderstorm outflow, and is expected to act as the corridor for additional thunderstorms development during the afternoon and evening. Weakly sheared nature of the environment suggests a predominantly multicellular mode with limited updraft strength and duration. Given the very moist character of the air mass (i.e. PW values of 2-2.25"), a few isolated water-loaded downbursts capable of damaging wind gusts could occur. However, widely spaced character of events and overall marginal nature of the threat merits keeping severe wind probabilities below 5% for this outlook. ..Mosier.. 07/29/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1155 AM CDT Fri Jul 29 2022 Valid 291700Z - 301200Z No changes. See previous discussion below. ..Bentley.. 07/29/2022 .PREV DISCUSSION... /ISSUED 0200 AM CDT Fri Jul 29 2022/ ...Synopsis... A large-scale ridge will remain centered over the western CONUS, while a low-amplitude shortwave trough tracks southeastward across the northern Rockies. Beneath the upper ridge, hot/dry conditions will result in widespread 10-15 percent minimum RH east of the Cascades into the northern Rockies. The low RH, coupled with breezy northerly surface winds over southeast OR, southwest ID, and northern NV will promote elevated fire-weather conditions during the afternoon -- especially owing to highly receptive fuels over the area. In addition, large-scale ascent ahead of the shortwave trough and favorable midlevel moisture/instability will support isolated to widely scattered high-based thunderstorms over the northern Rockies. As these storms overspread a hot/dry boundary layer and critically dry fuels, lightning-induced ignitions will be possible. Farther west, upslope flow and adequate instability will also support very isolated high-based thunderstorms along the Cascades in northern CA into southern OR -- where isolated ignitions remain a concern. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1610 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL/EASTERN VIRGINIA TO EASTERN MARYLAND/SOUTHERN DELAWARE
Mesoscale Discussion 1610 NWS Storm Prediction Center Norman OK 1124 AM CDT Fri Jul 29 2022 Areas affected...Central/eastern Virginia to eastern Maryland/southern Delaware Concerning...Severe potential...Watch possible Valid 291624Z - 291830Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms are expected to develop/increase this afternoon initially across Virginia near the Blue Ridge and spread eastward toward/across the Chesapeake bay vicinity. Isolated wind damage may occur with the strongest storms. Trends are being monitored for a possible Severe Thunderstorm Watch. DISCUSSION...Strong heating and ample insolation/boundary layer destabilization are occurring across the southern half of Virginia to the south of a southwest/northeast-oriented effective front from the central Appalachians toward the Delmarva, although buoyancy will be somewhat tempered by warm mid-level temperatures (-4 to -5C at 500mb) and poor mid-level lapse rates. Regardless, thunderstorms will develop and increase through mid-afternoon over the mountains and Blue Ridge vicinity and subsequently spread eastward. Influenced by the upper trough over the Great Lakes, a belt of moderately strong westerlies is noted, particularly with northward extent near/north of the frontal zone. This will support sustained multicells/linear segments as thunderstorms develop, and possibly even some transient supercells across east-central Virginia/eastern Maryland and Chesapeake Bay vicinity. A very moist boundary layer and steepening low-level lapse rates could yield some downbursts capable of isolated wind damage as the most probable severe hazard. ..Guyer/Grams.. 07/29/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...LWX...RNK... LAT...LON 36897666 36587907 37507911 38817740 38597490 37177583 36897666 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1108 AM CDT Fri Jul 29 2022 Valid 291630Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS VA AND CHESAPEAKE BAY VICINITY... ...SUMMARY... Potential for scattered damaging winds from strong to locally severe gusts is greatest across parts of Virginia and the Chesapeake Bay vicinity through early evening. ...VA and Chesapeake Bay vicinity... South of a slow-moving surface cold front, a southwest to northeast-oriented zone of differential boundary-layer heating is apparent from southwest VA to the Chesapeake. Scattered thunderstorms are expected to develop along this corridor through the afternoon. On the fringe of 35-40 kt mid-level westerlies in conjunction with a pronounced buoyancy gradient, a mix of multicell clusters and transient supercell structures are anticipated. Amid weak mid-level lapse rates, strong to locally severe gusts producing mainly tree damage should be the primary threat into early evening. ...Southern Appalachians to the Mid-South... Scattered thunderstorms are again expected along the composite outflow/differential heating corridors south of the quasi-stationary surface front. Isolated strong/damaging downbursts will be possible with water-loaded downdrafts on the fringe of modest mid-level westerlies. ...Red River Valley and TX Panhandle... Isolated to scattered thunderstorms are expected from late afternoon into mid-evening both along the surface cold front near the Red River and in a post-frontal regime over the TX Panhandle. Deep-layer shear will be weak across the region, especially for convection along the front. The latter will be compensated by a deeply mixed thermodynamic profile with hot temperatures south of the front. Isolated strong/damaging downbursts will be possible with water-loaded downdrafts. Farther west, slow-moving cells/clusters may contain a threat of both isolated, marginally severe wind/hail. ...Southern Great Basin... Around the southeast periphery of a mid-level anticyclone centered over northern CA, modest northeasterly flow of 15-20 kt will be maintained over southern NV. Boundary-layer dewpoints are generally in the low to mid 60s this morning and gradual clearing of clouds will allow strong surface heating this afternoon with MLCAPE increasing to 500-1500 J/kg. Isolated to scattered thunderstorms are expected to form by late afternoon close to the NV/UT border, and storms will subsequently spread south-southwestward on outflow into southern NV and adjacent areas of southeast CA. Given the modest buoyancy and steep low-level lapse rates, isolated severe outflow gusts up to around 70 mph will be possible with multicell clusters. ...Northern MT... A low-amplitude shortwave impulse over southeast BC will drift east across southern AB. Though moisture will be limited, deep boundary-layer mixing will occur as surface temperatures warm through the 90s. Weak ascent preceding the upper trough and weak low-level convergence along a surface trough will support isolated to scattered thunderstorms later this afternoon. Though low to mid-level flow will remain weak, deep inverted-v profiles will favor isolated strong outflow gusts of 50-60 mph. ...NE Panhandle vicinity... Isolated thunderstorms may develop along the northern periphery of the High Plains moisture plume during the late afternoon/early evening. Adequate veering of the wind profile with height (weak low-level southerlies to modest mid-level northwesterlies) will support a short-duration and very isolated threat for marginally severe hail/wind. ..Grams/Lyons.. 07/29/2022 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1226 PM CDT Thu Jul 28 2022 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF CENTRAL AND NORTHERN VIRGINIA AND THE DELMARVA PENINSULA.... ...SUMMARY... Damaging thunderstorm gusts may occur from the Ozarks/Mid-South to parts of the Mid-Atlantic region, as well as over parts of the southern High Plains. ...Synopsis... A mature mid-latitude cyclone is forecast to be centered over western Quebec early Friday morning. This cyclone is expected to weaken throughout the period, devolving into an open wave while also becoming more progressive. By early Saturday morning, this upper trough will have moved into the Canadian Maritime Provinces. At the same time, a shortwave trough is expected to rotate quickly through the base of this large cyclone/trough, moving from the Upper Midwest across the Upper and Lower Great Lakes regions and through the Northeast. Farther west, an upper ridge covering much of the West Coast will remain centered over northern CA, while subtropical ridging persists from the southern Plains through the Southeast. A frontal zone is expected to extend from east-central NM east-northeastward into the Upper OH Valley early Friday morning. Some modest southward/southeastward progression of this front is anticipated as it is reinforced by a secondary surge of dry, continental across the air from the northern/central Plains and Upper MS Valley throughout the day. ...Ozark Plateau/Mid-South/TN Valley/Mid-Atlantic... Ample low-level moisture and strong heating will destabilize the air mass in the vicinity of the frontal zone draped across the region. Convergence along this boundary, augmented by modest large-scale forcing for ascent as well as localized areas of lift near any convectively enhanced vorticity maximums, should result in afternoon thunderstorm development. Much of this development should be south of the stronger mid-level flow, leading to an outflow-dominant multicellular mode. Some loosely organized bowing line segments are possible. The only exception is across central/northern VA and adjacent MD and DE. In this region, thunderstorms should be coincident with at least modest mid-level flow. This increased mid-level flow will correspond with increasing dewpoints/buoyancy, increasing the chance for organized storms capable of strong wind gusts. As a result, wind probabilities were increased to 15%. ...Southern High Plains... Overnight showers and thunderstorms from Thursday night into Friday morning will likely reinforce the frontal zone expected to extend from east-central NM through central OK. This showers and thunderstorms should also reduce mid-level lapse rates, increase cloudiness, and reduce overall buoyancy across areas north of the front. Strong diurnal heating is still anticipated south of the front, resulting in deep boundary layer mixing as well as air mass destabilization. Isolated to scattered afternoon thunderstorm development is anticipated over this region. High-based character of these storms coupled with steep low-level lapse rates will result in the potential for a few damaging wind gusts. Adjustments to this risk area may be required in later outlook based on the position of the front. ..Mosier.. 07/28/2022 Read more

MD 1606 CONCERNING SEVERE THUNDERSTORM WATCH 505... FOR CENTRAL/EASTERN/NORTHERN NY
Mesoscale Discussion 1606 NWS Storm Prediction Center Norman OK 1217 PM CDT Thu Jul 28 2022 Areas affected...Central/eastern/northern NY Concerning...Severe Thunderstorm Watch 505... Valid 281717Z - 281915Z The severe weather threat for Severe Thunderstorm Watch 505 continues. SUMMARY...An evolving cluster across central NY should continue to pose a threat for two-three west/east-oriented swaths of damaging winds. DISCUSSION...Deepest updrafts are located on both the northern and southern flanks of an emerging cluster from the Finger Lakes to the Upper Saint Lawrence Valley. 17Z mesoanalysis indicates MLCAPE has increased to 1000-1500 J/kg ahead of this activity as surface temperatures have broadly warmed through the upper 70s to mid 80s. The BUF VWP has consistently sampled 40-kt westerlies as low as 2-km AGL in the wake of the cluster, while strong mid/upper-level speed shear evident in TYX will foster organization potential, including a threat for small hail. With a 52 mph gust measured at 1635Z at the Penn Yan NY Mesonet site, expect a threat for 45-60 mph gusts within the deepest cells and small bowing segments as they spread towards eastern NY. ..Grams.. 07/28/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BTV...ALY...BGM...BUF... LAT...LON 45017483 44997404 44977353 44877321 44147320 42777385 42507436 42517531 42577611 42907648 44167602 44707552 45017483 Read more

MD 1605 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR MID-MISSISSIPPI AND LOWER OHIO RIVER VALLEYS
Mesoscale Discussion 1605 NWS Storm Prediction Center Norman OK 1200 PM CDT Thu Jul 28 2022 Areas affected...Mid-Mississippi and lower Ohio River Valleys Concerning...Severe potential...Watch unlikely Valid 281700Z - 281900Z Probability of Watch Issuance...20 percent SUMMARY...Thunderstorms will continue to gradually increase in coverage and intensity through the afternoon hours, and may pose a damaging wind risk. Watch issuance is currently not anticipated. DISCUSSION...Regional reflectivity trends over the past hour reveal a broad MCV moving eastward across central Missouri. Lift ahead of this feature is promoting increasing cloud cover over the region. However, breaks in the clouds across southeast MO to the lower-OH River Valley have allowed for some diurnal destabilization. Temperatures rising into the mid 80s, coupled with low 70s dewpoints, are fostering MLCAPE around 1000 J/kg. Further evidence of this trend is noted in visible imagery as shallow convective cumulus, as well as a few deeper towers with occasional lightning, continue to increase in coverage. Regional VWPs from western MO are sampling 30-40 knot winds in the 5-7 km layer in the vicinity of the MCV, which is supporting stronger deep-layer shear than reflected in recent mesoanalyses. Consequently, the combination of improving thermodynamics and adequate kinematics may support a few strong to severe thunderstorms this afternoon. Thunderstorms intensifying ahead of the MCV or developing along a diffuse outflow boundary and/or the southward-moving cold front will likely consolidate into loosely organized clusters, though one or two semi-consolidated lines appear possible, as hinted by a few hi-res solutions. While damaging winds appear probable, confidence in the coverage of strong/severe convection remains limited given the marginal thermodynamic profiles and increasing cloud cover (which should act to slow further destabilization). ..Moore/Guyer.. 07/28/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PAH...ILX...LSX...SGF... LAT...LON 37639263 38489260 38679191 38928986 38858847 38438782 37588774 36868805 36788938 36909072 37109203 37639263 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1140 AM CDT Thu Jul 28 2022 Valid 281700Z - 291200Z The previous forecast remains on track, with no changes or additions made. Please see the previous forecast below for more details. ..Squitieri.. 07/28/2022 .PREV DISCUSSION... /ISSUED 0200 AM CDT Thu Jul 28 2022/ ...Synopsis... An amplified mid/upper-level ridge will remain in place over the northwestern CONUS, while a belt of modest midlevel northwesterly flow overspreads the northern Rockies. This large-scale pattern will result in elevated fire-weather conditions over parts of southeast OR, northern NV, and southwest ID -- where breezy northerly surface winds near 15 mph will overlap 10-15 percent minimum RH. In addition, isolated to widely scattered high-based thunderstorms are expected over parts of the northern Rockies, and critically dry fuels over this area will support isolated lightning-induced ignitions away from any precipitation cores. An isolated storm or two will also be possible along the Cascades in northern CA into southern OR, though confidence in storm development is currently too low for highlights here. Farther north along/east of the Cascades in WA, breezy terrain-enhanced surface winds and 10-15 percent RH could lead to locally elevated conditions during the afternoon. However, these conditions should generally be confined to terrain-favored areas and appear too localized for Elevated highlights. ...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 1130 AM CDT Thu Jul 28 2022 Valid 281630Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTHEAST STATES... ...SUMMARY... Occasional damaging wind gusts and marginally severe hail are expected across parts of the Northeast this afternoon. Isolated wind damage will also be possible from parts of the Mid-Atlantic to the Ozarks, and marginally severe wind/hail may occur near the Front Range in Colorado and across the High Plains. ...Northeast States... Initially isolated severe storms have already developed this morning across western New York, and this risk should further increase/develop eastward toward eastern New York and much of western New England this afternoon. For additional short-term details, see Mesoscale Discussion 1604. A deep mid-level low over northern Ontario will continue generally eastward toward northwest Quebec through tonight, with a base-embedded mid/high-level speed max (50-60 kt at 500 mb) over the Great Lakes transitioning east-northeastward. A related cold front will also move eastward with further thunderstorm development expected along/ahead of the front in addition to near a prefrontal trough across parts of the Mid-Atlantic and southeast New York vicinity. Mid-level lapse rates were observed to be weak in 12z observed upper-air data, but cloud breaks and a general prevalence of upper 60s F surface dewpoints will support upwards of 1000-1500 J/kg MLCAPE as additional heating occurs. The aforementioned speed max and tendency for strengthening winds aloft will maintain long and relatively straight hodographs with 40-50 kt effective shear. This will yield the possibility of a few supercells aside from more prevalent clusters/linear segments, with damage as the most common hazard. The overall severe risk should tend to diminish this evening as storms encounter a narrower warm sector and more marginally unstable air mass across Maine. ...Portions of the Mid-Atlantic to the Ozarks this afternoon... Have adjusted severe wind probabilities a bit northward near the Midwest synoptic front where severe-adequate destabilization may occur. Farther south, widely scattered thunderstorms should also form in the zone of differential heating, and the strongest storms could produce isolated wind damage with downbursts. Wind profiles will be relatively weak in the low-mid levels along the southern periphery of the early clouds/convection from northern Arkansas/southern Missouri to western Tennessee. However, strong surface heating and steep low-level lapse rates south of the clouds could support a few multicell storms/clusters capable of producing isolated strong/damaging outflow gusts near and just after peak heating. ...Eastern Colorado and central/southern High Plains... Outflow with overnight convection has moved southwestward to the Front Range in Colorado. Some clouds will linger across the eastern Plains of Colorado, and vertical shear will be weaker with less steep mid-level lapse rates compared to Wednesday afternoon. Still, boundary-layer dewpoints near 60 F, pockets of surface heating, and low-level upslope flow should support the development of scattered thunderstorm clusters this afternoon near the Front Range. The strongest storms will pose a threat for marginally severe hail and isolated strong-severe outflow gusts. ..Guyer/Moore.. 07/28/2022 Read more

WW 0505 Status Updates
STATUS FOR WATCH 0505 HAS NOT BEEN ISSUED YET Read more

WW 505 SEVERE TSTM MA NY PA VT LE LO 281605Z - 290000Z
URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 505 NWS Storm Prediction Center Norman OK 1205 PM EDT Thu Jul 28 2022 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of Western Massachusetts Central and Eastern New York Northeast Pennsylvania Vermont Lake Erie Lake Ontario * Effective this Thursday afternoon and evening from 1205 PM until 800 PM EDT. * Primary threats include... Scattered damaging wind gusts to 65 mph likely Isolated large hail events to 1 inch in diameter possible A tornado or two possible SUMMARY...Severe thunderstorms are expected to develop and increase through the afternoon, initially across central into eastern New York and possibly northeast Pennsylvania, before reaching western New England by late afternoon/early evening. Damaging winds are expected to be the primary hazard regionally. The severe thunderstorm watch area is approximately along and 90 statute miles north and south of a line from 30 miles northwest of Ithaca NY to 5 miles north of Lebanon NH. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU5). PRECAUTIONARY/PREPAREDNESS ACTIONS... REMEMBER...A Severe Thunderstorm Watch means conditions are favorable for severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings. Severe thunderstorms can and occasionally do produce tornadoes. && AVIATION...A few severe thunderstorms with hail surface and aloft to 1 inch. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 500. Mean storm motion vector 27030. ...Guyer Read more

No watches are valid as of Wed Jul 27 17:55:01 UTC 2022.

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