Severe Storms

MD 1823 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR SOUTHERN WV...SOUTHWEST VA
Mesoscale Discussion 1823 NWS Storm Prediction Center Norman OK 1114 AM CDT Sun Sep 25 2022 Areas affected...Southern WV...Southwest VA Concerning...Severe potential...Watch possible Valid 251614Z - 251815Z Probability of Watch Issuance...40 percent SUMMARY...Ongoing thunderstorms are expected to continue eastward into more of southern WV and western VA over the next few hours. A few strong gusts and isolated hail may accompany these storms. Convective trends will be monitored closely for the possible watch issuance. DISCUSSION...Recent radar imagery has shown in increase in storm intensity and coverage across southern WV and the KY/VA border vicinity. This increase appears to be associated with strengthening forcing for ascent attendant to the shortwave trough moving through the upper OH Valley. Brief clearing ahead of the ascent has allowed temperatures to increase into the mid to upper 60s. Even so, dewpoints remain in the mid 50s and the overall thermodynamic profile is characterized by modest buoyancy and relatively low EL heights. This should result in predominantly low-topped storms. Recent mesoanalysis places a corridor of 60 kt 500-mb winds from eastern KY through western VA. Fast (i.e. 40+ kt) storm motion is expected as a result, as well as the potential for a few stronger wind gusts as the storms move through. As such, damaging gusts will be the main severe threat, although isolated hail is also possible within robust updrafts given the cold mid-level temperatures. ..Mosier/Thompson.. 09/25/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LWX...RNK...RLX...MRX...JKL... LAT...LON 37518209 38068128 38278036 37937919 37057941 36588046 36638297 37518209 Read more

No watches are valid as of Sat Sep 24 18:00:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sat Sep 24 18:00:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Sat Sep 24 2022 Valid 251200Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY ACROSS PARTS OF THE UPPER OHIO VALLEY INTO THE NORTHERN MID ATLANTIC REGION... ...SUMMARY... Strong thunderstorms may impact parts of the upper Ohio Valley into the northern Mid Atlantic coast vicinity Sunday, posing at least some risk for severe weather. ...Synopsis... Mid/upper flow is in the process of amplifying across the mid-latitude Pacific into North America. This includes prominent ridging building across the Pacific coast through the Rockies and, by late Sunday into Sunday night, a significant short wave trough digging downstream, across the Upper Midwest into Ohio Valley. A preceding short wave trough is forecast to accelerate east of the lower Ohio Valley, before turning northeastward across the northern Mid Atlantic states and New England, within larger-scale troughing evolving across the Mississippi Valley through the Atlantic Seaboard. Models suggest that this evolving regime will be accompanied by the development of a broad surface low across parts of the lower Great Lakes into St. Lawrence Valley vicinity, and a reinforcing intrusion of cooler and/or drier air across much of the nation east of the Rockies Sunday through Sunday night. However, this is occurring in the wake of a substantive prior intrusion of cool/dry air, and in the wake of the Fiona, which is forecast to migrate north of the Canadian Maritimes into the Labrador Sea. As a result, it appears that low-level forcing for ascent and moisture return within the warm sector of the developing low will remain limited, which may tend to suppress the potential for vigorous thunderstorm development during this period. ...Mid/upper Ohio Valley into northern Mid Atlantic... The mid-level cold pool, and forcing for ascent in the exit region of the strong mid-level jet streak accompanying the lead short wave perturbation, seem likely to become the primary focus for any strong thunderstorm development Sunday. As the wave shifts east of the mid/upper Ohio Valley by midday, toward the northern Mid Atlantic coast through early evening, it appears that boundary-layer destabilization will remain rather modest. CAPE is generally forecast to peak around or below 500 J/kg along a developing warm frontal zone across parts of central and eastern Pennsylvania into Long Island/southern New England, and below 1000 J/kg ahead of the developing cold front across the Allegheny Plateau vicinity. However, this could be sufficient to support scattered thunderstorm development and, in the presence of strong shear (beneath 30-70+ kt flow in the 850-500 mb layer), at least some potential for organized severe thunderstorm development. This may include isolated to widely scattered supercells, particularly along the warm frontal zone, where various model output suggests that low-level hodographs might become supportive of the risk for a tornado or two, before convection wanes by Sunday evening. ..Kerr.. 09/24/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1148 AM CDT Sat Sep 24 2022 Valid 241700Z - 251200Z ...NO CRITICAL AREAS... No changes. See previous discussion below. ..Bentley.. 09/24/2022 .PREV DISCUSSION... /ISSUED 1136 PM CDT Fri Sep 23 2022/ ...Synopsis... Broad cyclonic flow aloft will develop from the Mid-Atlantic into the Great Lakes while the western upper-level trough will amplify today. A belt of stronger mid-level winds will reside across the northern and central Plains. At the surface, a cold front will slow its southward progression within the southern Plains while continuing to the east into the Ohio Valley. Fire weather concerns continue to appear low. Post-frontal downslope winds could approach 20 mph in southeastern Wyoming as well as parts of western/central Nebraska. RH will be lowest near the lee of the higher terrain, but 20% is possible farther east as well. With fuel dryness being mitigated by recent rainfall, elevated conditions that do develop will be localized. Lack of rain fall in Oklahoma has kept fuels dry. Southwesterly winds ahead of the front could reach 15-20 mph briefly. However, RH reductions will likely be marginal. Again, fire weather concerns will be localized. ...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 1118 AM CDT Sat Sep 24 2022 Valid 241630Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATER THIS AFTERNOON/EVENING FOR EXTREME SOUTHEASTERN MO...NORTHEASTERN AR...WESTERN TN AND NORTHWESTERN MS... ...SUMMARY... Isolated damaging wind gusts and large hail may occur this evening across extreme southeastern Missouri, northeastern Arkansas, and adjacent areas of western Tennessee and northwestern Mississippi. ...Northeast AR and vicinity later this afternoon/evening... Around the southwestern periphery of a midlevel trough over the Great Lakes, an embedded speed max will dig southeastward from the northern High Plains to the mid MS Valley by tonight. In advance of this speed max, low-level moisture will continue to spread northeastward from east TX to AR and southern MO, south of a weak front/wind shift that now extends from southern KS eastward into southern MO. With daytime heating/mixing in cloud breaks, MLCAPE will increase to near 1500 J/kg, in an environment with effective bulk shear of 35-45 kt with straight hodographs. This will conditionally favor splitting supercells by this evening from extreme southeast MO into northeast AR. The main concern in this area is the specific focus for storm development this afternoon/evening. A band of mid clouds will likely persist from OK into northern AR as part of a remnant monsoonal moisture plume from the southern Rockies, and these clouds will mute surface heating in a zone immediately south of the subtle front/wind shift. Thus, with relatively subtle forcing for ascent, at least isolated thunderstorm development is possible both north and south of this cloud band on the wind shift and south in the differential heating zone, depending on how persistent the thicker clouds will be through the afternoon. The degree of surface heating/mixing will drive low-level lapse rates, downdraft potential, and any resultant threat for wind damage. Given the potential for splitting supercells with long hodographs, isolated hail may also occur. Given the subtle nature of the ascent and the mesoscale influence/location of the cloud band, will maintain a broader MRGL area, but acknowledge the potential for two separate, smaller corridors of wind/hail threat from mid-late afternoon into this evening. ..Thompson/Weinman.. 09/24/2022 Read more

No watches are valid as of Fri Sep 23 17:47:02 UTC 2022.

No Mesoscale Discussions are in effect as of Fri Sep 23 17:47:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1209 PM CDT Fri Sep 23 2022 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE AREA CENTERED ON CENTRAL AND EASTERN ARKANSAS... ...SUMMARY... A few strong thunderstorms may develop Saturday afternoon and evening from parts of Arkansas into adjacent portions of the Missouri Bootheel, western Tennessee, and northwest Mississippi. Isolated damaging wind gusts appear to be the primary threat. ...Synopsis... A mid-level speed max over MT early Saturday morning will quickly move east-southeast to the mid MS Valley by early Sunday morning. In the low levels, surface high pressure initially over the Appalachians will move east of the Carolina coast, while weak return flow in response to weak low pressure develops over the MS Valley before moving into the Great Lakes late. The southern portion of stronger westerlies will overspread a weak to moderately unstable (750-1500 J/kg MLCAPE) warm sector centered over AR. The latest model guidance indicates isolated to perhaps widely scattered storms developing late Saturday afternoon into the early evening from central AR northeastward to the MO Bootheel region. A couple of the storms could yield strong locally damaging gusts before this activity weakens after sunset. Elsewhere, general thunderstorms are expected over parts of the Great Lakes/OH Valley, southern half of the FL Peninsula, and portions of the Desert Southwest. ..Smith.. 09/23/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1124 AM CDT Fri Sep 23 2022 Valid 231700Z - 241200Z ...NO CRITICAL AREAS... The current forecast is on track. See discussion below for more details. ..Thornton/Weinman.. 09/23/2022 .PREV DISCUSSION... /ISSUED 1231 AM CDT Fri Sep 23 2022/ ...Synopsis... An upper-level trough will continue eastward through the northern Plains into parts of the upper Midwest today. Farther west, ridging aloft will begin to amplify along the western coast. At the surface, a cold front will move out onto the northern and central Plains. High pressure will increase within the intermountain West. Localized elevated conditions are possible from central Montana into northeastern Colorado as downslope winds increase to around 20 mph. Some areas may experience RH as low as 15-20%. Given recent precipitation, significant fire potential will be low. ...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 1113 AM CDT Fri Sep 23 2022 Valid 231630Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis... Within the primary branch of the westerlies, a midlevel shortwave trough will move east-southeastward from the northern Plains to the Upper Midwest by tonight. Low-level moisture return remains quite limited across the Plains in advance of an associated lee trough, as a result of a prior frontal intrusion to the Gulf coast. Very weak buoyancy within a midlevel moisture plume across KS/NE, in combination with relatively steep midlevel lapse rates from NE into the eastern Dakotas, could be sufficient for isolated/elevated thunderstorms in the zone of ascent preceding the midlevel trough. Otherwise, scattered thunderstorms are expected along the primary baroclinic zone across central FL, and within the lingering monsoonal moisture plume with daytime heating over the higher terrain in AZ/NM this afternoon. ..Thompson/Kerr.. 09/23/2022 Read more

No watches are valid as of Thu Sep 22 17:52:01 UTC 2022.

No Mesoscale Discussions are in effect as of Thu Sep 22 17:52:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Thu Sep 22 2022 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... No severe threat is expected over the continental United States on Friday. ...Synopsis... A mid-level anticyclone will remain over the southern Great Plains while a mid-level trough will progress east across the northern Great Plains into the Upper Midwest. A narrow moist sector resulting in weak instability may result in a few thunderstorms across the eastern Dakotas and parts of the Upper Midwest. Elsewhere, general thunderstorms are also forecast across the FL Peninsula and the Desert Southwest. Weak buoyancy/shear will preclude organized severe thunderstorms. ..Smith.. 09/22/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1126 AM CDT Thu Sep 22 2022 Valid 221700Z - 231200Z Morning observations show winds across the Columbia Basin sustained at 10-15 mph, gusting to around 20 mph, with temperatures warming into the mid 50s to 60s. Through the afternoon, increasing westerly winds and downslope warming and drying could lead to elevated fire-weather conditions. See discussion below for more details. ..Thornton/Bentley.. 09/22/2022 .PREV DISCUSSION... /ISSUED 0102 AM CDT Thu Sep 22 2022/ ...Synopsis... A closed mid/upper-level low will cross the northern Rockies, while an expansive large-scale ridge remains centered over TX. At the surface, low pressure will deepen over the northern High Plains, with a lee trough extending southward along the central High Plains. ...Columbia Basin... On the backside of the mid/upper-level low, enhanced northwesterly flow aloft will overspread the Cascades, favoring dry/breezy conditions across the Columbia Basin. Here, 15-20 mph sustained westerly surface winds coupled with 20-25 percent RH (aided by downslope warming/drying) will yield elevated to locally critical fire-weather conditions during the afternoon. ...Northern/Central Rockies and Adjacent Plains... Breezy southerly surface winds will develop across the northern and central Plains in response to the lee troughing, while strong westerly surface winds are expected over WY. For the Plains, a minimal overlap of strong surface winds and low RH should generally mitigate the fire-weather threat, though locally elevated conditions could still occur where fuels are dry. Over WY, a corridor of strong westerly surface winds could overlap dry boundary-layer conditions, though recent/ongoing precipitation casts uncertainty on fuel receptiveness. ...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 1056 AM CDT Thu Sep 22 2022 Valid 221630Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS COASTAL SOUTHERN NEW ENGLAND TO EASTERN NORTH CAROLINA...AND SOUTHEAST MONTANA TO NORTHEAST WYOMING... ...SUMMARY... Isolated damaging winds remain possible this afternoon from coastal southern New England into eastern North Carolina. Isolated marginally severe hail/wind may also occur across a portion of southeast Montana and northeast Wyoming later this afternoon. ...Southern New England to NC... Potential still exists for convection to briefly strengthen from NJ to southern New England. A confined corridor of robust insolation from NJ southward yielded surface temperatures warming into the upper 70s to mid 80s just ahead of mixed convective/stratiform frontal rain bands. The time-window for convection to intensify before the front shifts off the coast is limited to the next hour or two, but strong deep-layer flow will support a conditional damaging wind threat along the immediate coastal areas. From the Delmarva into eastern NC, a longer duration period of robust boundary-layer heating will yield very warm surface temperatures and a relatively deeper mixed boundary-layer. Observed 12Z soundings sampled very poor 600-400 mb lapse rates south of the intense mid-level jet centered across the Mid-Atlantic to New England, where 500-mb temps were -4 to -6 C. This suggests convection developing along the trailing extent of the cold front impinging from the northwest will struggle to deepen and produce lightning. By late afternoon, there may just enough slight cooling aloft coupled with peak boundary-layer heating to support a few stronger gusts in convection that spreads towards the coast through early evening. ...Southeast MT and northeast WY... A shortwave trough centered on northwest MT will gradually shift east across the state through the period. While a leading lobe of ascent is moving through eastern MT late this morning, the next lobe will shift east-northeast from the Yellowstone/Upper Snake Valley area. A pocket of 500-1000 J/kg of MLCAPE should develop between these two waves in the lee of the Big Horns where steepening mid-level lapse rates overspread modest boundary-layer heating. Although forecast soundings indicate pronounced weaknesses in the hodograph through 600 mb where surface-based storms are expected, strong speed shear above that will yield potential for a few cells with transient mid-level rotation. Marginally severe hail and isolated strong to localized severe wind gusts will be possible for a few hours centered on late afternoon. ..Grams/Lyons.. 09/22/2022 Read more

No watches are valid as of Wed Sep 21 18:05:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Wed Sep 21 2022 Valid 221200Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE MID-ATLANTIC STATES INTO NORTH CAROLINA... ...SUMMARY... An isolated threat for damaging thunderstorm gusts will be possible on Thursday across parts of the Mid Atlantic southwestward into North Carolina. ...Mid-Atlantic states into NC... A large-scale mid-level trough initially over the Great Lakes will move east-southeast during the period and reach the coast of the Mid-Atlantic states/Northeast by early Friday morning. In the low levels, a cold front over the Appalachians Thursday morning will push southeast during the day and reach the southern portion of the Delmarva southwestward into the Carolina Piedmont by peak heating. Weak to moderate buoyancy (750-1500 J/kg MLCAPE) is forecast ahead of the front from the Delmarva southwest to the Research Triangle. Although 0-2 km lapse rates will steepen (8 deg C/km) through the early to mid afternoon, mid-level lapse rates will remain limited. Around 30-kt effective shear will probably support a few organized multicells/line segments where the primary hazard will be locally damaging gusts. This activity will likely weaken by early evening as instability wanes. ...Southeast New England... Scattered to numerous showers and a few thunderstorms are expected Thursday morning from the lower Hudson Valley northeastward into southern ME. Considerable cloud cover will likely encompass much of this region ahead of the front. However, relatively moist low levels could lead to weak destabilization during the morning. Forecast soundings show a strong wind profile but uncertainty remains whether a few surface-based storms will develop in the RI and southeast MA vicinity before the front moves offshore. Will defer the inclusion of low-severe probabilities for the time being. Elsewhere, general thunderstorms are forecast across a large part of the Four Corners northward into the north-central Rockies and adjacent plains. ..Smith.. 09/21/2022 Read more

MD 1812 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTH-CENTRAL/NORTHEAST OH...NORTHWEST PA...FAR SOUTHWEST NY
Mesoscale Discussion 1812 NWS Storm Prediction Center Norman OK 1231 PM CDT Wed Sep 21 2022 Areas affected...North-Central/Northeast OH...Northwest PA...Far Southwest NY Concerning...Severe potential...Watch possible Valid 211731Z - 211930Z Probability of Watch Issuance...40 percent SUMMARY...Strong to severe thunderstorms capable of isolated hail and/or damaging gusts may occur from north-central/northeast OH into southwest NY this afternoon. Uncertainty regarding severe thunderstorm coverage currently merits low watch probabilities. DISCUSSION...A large area of showers and embedded thunderstorms continues to move eastward/southeastward across southwestern Ontario and Lake Erie. Current motion of the leading edge of this area is estimated at 35-40 kt, which brings it to the eastern shore of Lake Erie around 18Z. Cloud cover associated with this precipitation has already spread into areas in the lee of Lake Erie, which is tempering diurnal heating. Current observations show temperatures in the mid 70s across southwest NY, increasing into the low 80s in north-central OH. Dewpoints increase from the mid 60s across southwest NY to the upper 60s across north-central OH. These surface conditions are precluding the erosion of the convective inhibition in place, particularly across western PA and southwest NY. Thunderstorm development is still expected as this area of ascent reaches the lee of Lake Erie, but, given the low-level stability still in place, most of these storm will likely be elevated. The best chance of surface-based storms is back across north-central/northeast OH. Elevated character to most of the storms should limit the overall coverage, with isolated hail as the most likely risk. A few strong gusts could also occur, particularly if any bowing line segments are able to develop/mature. ..Mosier/Grams.. 09/21/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF...CTP...PBZ...CLE... LAT...LON 41398287 41478180 42197992 42647897 42027832 41197951 40888078 40728290 41398287 Read more

MD 1811 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PORTIONS OF WESTERN AND CENTRAL UTAH AND EASTERN NEVADA
Mesoscale Discussion 1811 NWS Storm Prediction Center Norman OK 1226 PM CDT Wed Sep 21 2022 Areas affected...portions of western and central Utah and eastern Nevada Concerning...Severe potential...Watch possible Valid 211726Z - 211930Z Probability of Watch Issuance...60 percent SUMMARY...Ahead of a deep upper low, scattered thunderstorm development/ organization is expected early this afternoon. Damaging wind gusts, and hail will be possible with strong to severe storms later this afternoon. Conditions are being monitored for a possible watch. DISCUSSION...Evident on regional water vapor imagery, a deep upper low and 70-80 kt cyclonically curved jet streak over the western Great Basin were supporting broad diffluence and lift across much of the intermountain West. With the commencement of diurnal heating, increasingly agitated cumulus was noted on area visible imagery across the higher terrain of eastern NV and western UT. Further destabilization is expected as temperatures warm and as surface dewpoints in the 40s and 50s F are transported northward from the Southwest. While not overly steep, 7 C/km mid-level lapse rates were observed east of the cold core center, aiding in the development of weak buoyancy (MUCAPE of 500-1000 J/kg). As ascent increases through the late morning and early afternoon, scattered thunderstorms should develop and detach from the higher terrain before spreading north/northeastward. Favorable deep-layer shear (0-6 km 50-60 kt) will likely support a mix of cluster and more discrete storms with some mid-level storm rotation possible. Low-level inverted-v structures and strong mid-level flow will favor a risk for damaging wind gusts, some of which could be significant with stronger downdrafts able to develop. Some severe hail may also be possible given elongated upper-level hodographs and cool mid-level temperatures, though the weaker buoyancy casts some uncertainty on updraft strength. Latest hi-res guidance and observations suggest storm development may occur as early as 18z across portions of southwestern UT, closest to the strongest ascent and orographic lift. Storms should quickly spread north/northeast into western and central UT with a severe risk through this afternoon and into the evening. With scattered storm coverage and greater potential for organization expected, conditions are being monitored for a possible weather watch. ..Lyons/Grams.. 09/21/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SLC...VEF...LKN... LAT...LON 37241374 37231399 37501415 38381429 39441450 39911459 40421484 40981517 41341539 41701526 41921489 41981418 41981283 41861234 41571193 41181179 40741168 39281221 37811286 37461319 37241374 Read more