Severe Storms

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1024 AM CST Mon Nov 21 2022 Valid 211700Z - 221200Z ...NO CRITICAL AREAS... No changes, fire-weather concerns across the CONUS are low. ..Lyons.. 11/21/2022 .PREV DISCUSSION... /ISSUED 1128 PM CST Sun Nov 20 2022/ ...Synopsis... Surface high pressure and associated cooler air will overspread much of the MS Valley eastward as well as the Interior West while multiple shortwave mid-level troughs traverse the CONUS today. Dry surface air will meander over a long corridor from the central Plains to the OH Valley/central Appalachians this afternoon, perhaps supporting very brief, localized wildfire concerns. Otherwise, widespread, significant wildfire-spread potential appears limited across the CONUS. ...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 1010 AM CST Mon Nov 21 2022 Valid 211630Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for thunderstorms remains negligible across much of the U.S. today through tonight. ...Discussion... Mid/upper flow has trended more zonal across North America, with much of the U.S. now most prominently under the influence of westerlies emanating from the mid-latitude Pacific. However, flow remains broadly confluent inland of Pacific coastal areas through the Atlantic Seaboard, with relatively cool and stable conditions only slowly beginning to modify. This includes seasonably cold surface ridging being maintained from the lee of the southern Rockies, as far south as the northwestern Gulf coast vicinity, into the western Atlantic. Although insolation and moistening northeasterly to easterly near-surface flow may begin to modify the boundary layer across the Florida Peninsula (particularly southeastern through east central portions), weak forcing for ascent and mid-level lapse rates may only allow for scattered shower development with some potential to occasionally produce lightning. ..Kerr/Thornton.. 11/21/2022 Read more

No watches are valid as of Sun Nov 20 18:16:02 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Nov 20 18:16:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1116 AM CST Sun Nov 20 2022 Valid 211200Z - 221200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Monday. ...Synopsis and Discussion... A positively tilted, southern-stream shortwave trough will develop eastward Monday from the southern Plains to the lower MS Valley and Southeast. Surface high pressure extending from TX to the East Coast will inhibit the inland return of low-level moisture along much of the Gulf Coast. Accordingly, the lack of appreciable instability is expected to limit thunderstorm potential over a large majority of the CONUS, with one exception. Rich low-level moisture should return slowly northward across the FL Peninsula through the period. Even though mid-level lapse rates will remain poor, modest heating of this moist low-level airmass should encourage the development of weak instability by Monday afternoon, particularly over south FL where low 70s surface dewpoints are forecast. Isolated thunderstorms capable of producing occasional lighting flashes may preferentially form along the Atlantic Coast sea breeze given weak easterly low-level flow. Deep-layer shear is expected to remain modest over the surface warm sector, which coupled with the poor lapse rates should limit updraft organization and intensity. ..Gleason.. 11/20/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1039 AM CST Sun Nov 20 2022 Valid 201700Z - 211200Z ...NO CRITICAL AREAS... Weak offshore flow across southern CA should continue to fade this afternoon with a low-end risk for elevated fire-weather conditions. Otherwise, no changes have been made to the current outlook; fire concerns are low across the CONUS. ..Lyons.. 11/20/2022 .PREV DISCUSSION... /ISSUED 1148 PM CST Sat Nov 19 2022/ ...Synopsis... Large-scale surface high pressure and associated cool temperatures should mitigate significant wildfire-spread concerns across the Interior West and eastern CONUS. Some dry, occasionally breezy conditions may support a brief, localized wildfire-spread threat across the central Plains as a weak mid-level trough overspreads the region and encourages some surface lee troughing/gradient winds. ...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 1020 AM CST Sun Nov 20 2022 Valid 201630Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis/Discussion... In mid/upper levels, mean troughing will be maintained over eastern Canada through the period. However, the strong subsidiary trough -- now apparent in moisture-channel imagery from near James Bay across parts of the Mid-Atlantic region -- will move eastward through New England around 00Z and Atlantic Canada thereafter. This process will shift low-level winds unfavorably for lake-effect bands over the lower Great Lakes, foster dry advection in the boundary layer, and lower effective tropopause levels. Those, in turn, will lessen lightning potential through the afternoon. A positively tilted, southern-stream shortwave trough was evident from northwestern OK across the TX Panhandle, central NM, southeastern AZ, and the northern Gulf of California. The trough should pivot eastward through the period -- with faster translation of its middle/southern parts, while retaining positive tilt. By 12Z, the trough should extend across central OK, northwest TX, extreme southeastern NM, far west TX, and central Sonora. To its southeast over south TX, a broad plume of elevated low-level warm advection and moisture advection/transport will persist, supporting increasing convective potential (including isolated to widely scattered thunderstorms) overnight into early morning. At the surface, 15Z analysis showed a quasistationary front across Great Abaco, Bahamas, southwestward over the Gulf Stream to very near Elliott Key and Key Largo FL, then across the Straits just south of the Lower/Middle Keys. Minor oscillations in frontal position are possible through the period, but it generally should remain quasistationary. Most associated convection has remained (and should continue to be) just below ideal icing layers for lightning, based on modified MFL/EYW RAOBs and radar cross-sections. Still, isolated lightning has been observed sporadically south of the Lower Keys, and weak storm-scale rotation has been noted in cells over the Straits, east of both Key Largo and Miami-Dade County. This may prompt occasional deepening of updrafts briefly favorable for lightning. Activity should remain too weak for a severe threat. ..Edwards/Thornton.. 11/20/2022 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CST Sat Nov 19 2022 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Sunday. ...Synopsis and Discussion... A large-scale upper trough will develop northeastward over the eastern states on Sunday. A separate, southern stream shortwave trough is forecast to advance eastward across parts of the southern Plains through the period. A broad area of surface high pressure will extend from the southern Plains to much of the eastern CONUS. A dearth of low-level moisture over the vast majority of the CONUS will generally hinder thunderstorm development, with a few exceptions. Isolated lightning flashes may occur along/near a small part of Lake Ontario in association with a lake-effect snow band. This potential should slowly diminish through the day as the band gradually weakens. Other isolated thunderstorms may develop through the day across parts of south FL and the Keys. This area will have access to greater low-level moisture, but both instability and large-scale ascent are expected to remain rather weak. Finally, a few lightning flashes appear possible with elevated convection across parts of TX, mainly Sunday night into early Monday morning, as the previously mentioned shortwave trough approaches from the west. ..Gleason.. 11/19/2022 Read more

No watches are valid as of Sat Nov 19 17:33:01 UTC 2022.

No Mesoscale Discussions are in effect as of Sat Nov 19 17:33:01 UTC 2022.

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1043 AM CST Sat Nov 19 2022 Valid 191700Z - 201200Z No changes have been made to the current forecast. Offshore flow should linger through this evening before weakening overnight. Occasional elevated fire-weather conditions are possible. See the previous discussion for more information. ..Lyons.. 11/19/2022 .PREV DISCUSSION... /ISSUED 0114 AM CST Sat Nov 19 2022/ ...Synopsis... Surface high pressure and associated cold air should envelop much of the CONUS, limiting significant wildfire-spread potential. Some fire-spread potential may exist across higher-terrain areas of southern California with continued dry and strong offshore flow, mainly during the first half of the period, with low-end Elevated highlights maintained. The main limiting factor to more robust wildfire-spread potential continues to be poorly receptive fuels. ...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 1021 AM CST Sat Nov 19 2022 Valid 191630Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Synopsis... Upper troughing is forecast to dig east-southeastward across the Upper Great Lakes/Midwest region today, and then sweep eastward across the Lower Lakes and into the Northeast/New England overnight. Meanwhile, in the West, a weak trough will drift across the southwestern deserts, while ridging prevails across the West Coast states and into the Great Basin. At the surface, cold high pressure will largely prevail across the country, though a reinforcing/arctic cold front will cross the northeastern quarter of the country through the period. A few lightning flashes will be possible across the Great Lakes region today, as the reinforcing surge of cold air spreads across the still-warm lakes, resulting in low-topped convective snow showers/bands. A couple of flashes may also persist across parts of coastal southern Texas, and a flash or two may also occur with isolated convection over southern Florida and the Keys. Elsewhere, stable conditions will preclude thunder potential. ..Goss.. 11/19/2022 Read more

No watches are valid as of Fri Nov 18 18:01:01 UTC 2022.

MD 1959 CONCERNING HEAVY SNOW FOR AREAS NORTHEAST OF LAKE ERIE ACROSS THE SOUTHERN PORTION OF THE BUFFALO METRO
Mesoscale Discussion 1959 NWS Storm Prediction Center Norman OK 1159 AM CST Fri Nov 18 2022 Areas affected...Areas northeast of Lake Erie across the southern portion of the Buffalo Metro Concerning...Heavy snow Valid 181759Z - 182200Z SUMMARY...A lake-effect snow band is likely to persist through the afternoon with snow rates 2+ inches per hour. DISCUSSION...A persistent band of lake-effect snow, around 230 km long, across Lake Erie has made a slight shift southward through the morning. Upstream, a shortwave trough is rotating within the main open wave trough with increasing DCVA and large scale ascent across the Ohio River Valley progged to shift northward into New York by 20-21z. Ahead of this feature, southwesterly winds and long moisture fetch continues across Lake Erie. Lake induced 0-3 km lapse rates of 9+ C/km will continue through afternoon as colder air aloft interacts with warm lake water below. The primary snow band is currently located across the area of greatest surface convergence, which has been shifting southward through the morning. This band should see an uptick in intensity over the next couple of hours with rates 2+ inches per hour primarily across the southern Buffalo Metro extending northward into northwestern Wyoming County. Near zero visibility will be possible at times with dangerous travel conditions likely. ..Thornton/Guyer.. 11/18/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 42927853 42897889 42837910 42727914 42627916 42577900 42587870 42607855 42657839 42727816 42807811 42907821 42927853 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1116 AM CST Fri Nov 18 2022 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms appears negligible across the U.S. Saturday through Saturday night. ...Synopsis... Cyclonic flow aloft will persist across the CONUS on Saturday. A pair of shortwave troughs will progress through this cyclonic flow, with the northernmost wave moving from the Upper Midwest eastward across the Great Lakes, OH Valley, and Northeast. The southernmost shortwave will be less progressive, gradually moving from southern CA/Lower CO River Valley eastward/southeastward into more of the Southwest and northern Mexico. Progression of the northern shortwave and an associated cold front will reinforce the stable continental air mass in place over the majority of central and eastern CONUS. This should preclude thunderstorm development east of the Rockies, with the exception of a few localized areas. One area is along the TX Coast, where showers and a few embedded thunderstorms are possible early Saturday morning. Isolated thunderstorms are also possible Saturday night into Sunday morning across south FL and the FL Keys amid modest low-level moisture return and easterly low-level flow. Lastly, a few flashes are possible over and in the immediate lee of Lakes Erie and Ontario, where warm lake waters and convective heavy snow bands could result in isolated lightning flashes. ..Mosier.. 11/18/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1039 AM CST Fri Nov 18 2022 Valid 181700Z - 191200Z ...Southern California... Light offshore winds and dry surface conditions are expected much of today ahead of an advancing mid-level trough. While gusts may occasionally reach 15-20 mph in the higher terrain, widespread elevated fire-weather conditions are not expected through the daytime hours. Stronger pressure gradients will increase overnight and into early Saturday as the trough and enhanced mid-level northeasterly flow move over southern CA. Terrain enhanced gusts to 30 mph and humidity below 20% are possible, supporting some risk for elevated to locally critical fire-weather conditions. However, fuels remain only marginally supportive. See the previous discussion for additional information. ..Lyons.. 11/18/2022 .PREV DISCUSSION... /ISSUED 1147 PM CST Thu Nov 17 2022/ ...Synopsis... A broad, positively tilted mid-level trough will encourage deep-layer northwesterly flow and at/below freezing surface temperatures across much of the central and northern CONUS, mitigating widespread significant wildfire-spread potential. However, northerly, offshore deep-layer flow is expected to develop along the southern California coastline. As such, dry and breezy conditions may develop in higher-terrain areas of the transverse ranges toward the end of the period (i.e. 06-12Z Saturday). Elevated highlights have been introduced. However, these highlights delineate what is expected to be a lower-end event since fuels currently appear poorly to (at best) marginally receptive to wildfire spread. ...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 1030 AM CST Fri Nov 18 2022 Valid 181630Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected through tonight. ...Discussion... Most of the CONUS will be influenced by longwave troughing and associated cool/cold continental trajectories. Related to a belt of southern-stream westerlies, weak cyclogenesis is expected over the northwest Gulf of Mexico late tonight, with increasing warm advection and the gradual development of weak elevated buoyancy near the Texas coast. This may support isolated thunderstorm development late tonight/early Saturday. Occasional lightning flashes will also continue through this evening, particularly in vicinity of Lake Erie and Lake Ontario in association with lake-effect snow bands. This convective potential should somewhat diminish late tonight. ..Guyer/Thornton.. 11/18/2022 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1117 AM CST Thu Nov 17 2022 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Friday. ...Synopsis... Broad upper troughing will be maintained across the CONUS on Friday as a series of shortwave troughs move through the northern stream from the northern Plains across the mid/upper MS Valley, Great Lakes, and Northeast. Another shortwave trough is expected to become displaced from the main branch as it moves southward across CA. Persistent upper troughing will help maintain a stable, continental air mass across the CONUS throughout the period. The aforementioned series of shortwaves result in cooling mid-level temperatures above the still-warm Lower Great Lakes. This will contribute to additional steepening of low-level lapse rates, enhancing evolving bands of sustained low-topped lake-effect convection. Thermodynamic profiles may become conducive to charge separation and occasional lightning flashes in the more vigorous activity. Some moisture return is anticipated across deep South TX, with surface cyclogenesis beginning just off the coast early Saturday morning. The warm sector will likely remain offshore, but warm air advection Friday night/Saturday morning will result in showers along the coast, with a few embedded thunderstorms possible. ..Mosier.. 11/17/2022 Read more

No watches are valid as of Thu Nov 17 17:22:02 UTC 2022.

No Mesoscale Discussions are in effect as of Thu Nov 17 17:22:02 UTC 2022.