Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1019 AM CST Wed Nov 23 2022 Valid 231630Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms appears negligible across the U.S. today through tonight. ...Synopsis... Within a belt of westerlies emanating from the mid-latitude Pacific, models indicate that there will be further amplification within the flow across western North America through this period. This likely will include building mid-level ridging across and inland of the U.S./British Columbia Pacific coast, and digging mid-level troughing within split downstream branches near and east of the Rockies. It still appears that the more amplified of these perturbations will evolve in the southern branch, and include a developing mid-level low near the Colorado into New Mexico Rockies later today through tonight. Farther downstream, as a deep mid-level low continues to form while redeveloping across and southeast of the Canadian Maritimes, it appears that the persistent confluent mid-level regime across the eastern U.S. may become more focused across and just east of the Atlantic Seaboard. Beneath this regime, models indicate that cold surface ridging will be maintained and reinforced across the Atlantic Seaboard. As some erosion of this ridging commences across the northwestern Gulf of Mexico into portions of the southern Great Plains and lower Mississippi Valley, it appears that more prominent surface ridging, developing across the Intermountain West and Rockies, will begin to build into the Great Plains. And, surface cyclogenesis will remain suppressed within weak surface troughing to the lee of the southern Rockies. ...Southern Great Plains vicinity... On the southwestern periphery of the eastern surface ridging, modest low-level moisture return is already underway across and north-northeast of the lower Rio Grande Valley. A gradual moistening likely will continue within a narrow plume on the eastern periphery of a low-level jet (roughly 30+ kt around 850 mb), north-northeastward toward the Ozark Plateau through daybreak Thursday. However, this is occurring above an initially cold/stable surface-based layer. While there probably will be some modification of this air mass today through tonight, low cloud cover and precipitation will contribute to the maintenance of a substantive low-level/near-surface inversion layer across most areas north of the middle Texas coastal plain. Weak boundary-layer destabilization appears possible overnight across the coastal plain, but this seems likely to remain capped beneath warming layers aloft. North of a College Station/Temple line into areas near/northwest of the Ark-La-Tex, strengthening large-scale forcing for ascent is expected to support increasing thunderstorm development late this evening into the overnight hours. Modest to weak elevated instability and shear (within the relevant potential convective layer) likely will minimize the risk for severe weather. ..Kerr/Thornton.. 11/23/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1004 AM CST Wed Nov 23 2022 Valid 231700Z - 241200Z ...NO CRITICAL AREAS... No changes have been made to the current outlook. Brief locally elevated conditions will remain possible today ahead of a surging cold front in eastern CO. However, temporal and spatial coverage should remain below criteria for elevated highlights. Gusty downslope winds and brief elevated fire-weather conditions may develop over portions of the LA basin and southern CA late tonight into early D2/Thur. See the previous discussion. ..Lyons.. 11/23/2022 .PREV DISCUSSION... /ISSUED 0111 AM CST Wed Nov 23 2022/ ...Synopsis... A mid-level trough will deepen across the Rockies, encouraging surface cyclone development across the central/southern High Plains. Dry downslope flow along the lee of the Rockies may encourage brief bouts of Elevated surface conditions across portions of the central High Plains, with the brevity of these conditions precluding fire weather highlights. Elsewhere across the CONUS, relatively quiescent fire weather conditions are expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Nov 22 18:18:01 UTC 2022.

No Mesoscale Discussions are in effect as of Tue Nov 22 18:18:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CST Tue Nov 22 2022 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are unlikely on Wednesday. General thunderstorms are likely from northeast Texas into eastern Oklahoma and western Arkansas overnight. ...Discussion... A surface high will remain over the eastern CONUS with winds gradually veering to easterly over the Gulf of Mexico. Modest surface moisture return will occur Wednesday night across southeast TX, as surface pressures lower ahead of an upper low dropping south across CO and NM. Meanwhile, a cold front will surge south across the central and southern High Plains in advance of the upper low, well west of the developing moist plume. Moistening just above the surface will occur from eastern TX into AR as southwesterly 850 mb winds average 30-40 kt. Lift from warm advection will lead to scattered showers, with thunderstorms expected Wednesday night after about 05Z. Forecast soundings show elevated instability up to 500 J/kg developing from central and northern TX into southeast OK, suggesting little if any severe hail threat given only modest effective-layer shear and midlevel lapse rates near 6.5 C/km. ..Jewell.. 11/22/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1032 AM CST Tue Nov 22 2022 Valid 221700Z - 231200Z ...NO CRITICAL AREAS... Brief, locally elevated fire weather conditions are possible today across portions of the High Plains. Dry downslope flow may occasionally gust to near 15 mph with surface humidity below 20%. Freeze cured fuels may support some fire spread, but confidence in higher fire-weather concerns is low. See the previous discussion. ..Lyons.. 11/22/2022 .PREV DISCUSSION... /ISSUED 1246 AM CST Tue Nov 22 2022/ ...Synopsis... A mid-level trough will traverse the Pacific Northwest and amplify over the central Rockies today, with surface high pressure overspreading much of the CONUS, promoting weak surface winds and limiting significant wildfire-growth potential. Dry air will continue to meander across southern California and the central High Plains toward the central Appalachians during the afternoon, supporting brief, localized wildfire-spread potential. ...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 1015 AM CST Tue Nov 22 2022 Valid 221630Z - 231200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Showers and a couple of thunderstorms with gusty winds are possible late this afternoon across southern Washington and northern Oregon coastal areas. Otherwise, the risk for thunderstorms remains negligible across much of the remainder of the U.S. through tonight. ...Synopsis... Amplification within one belt of westerlies across the mid-latitude Pacific is underway. This is forecast to include large-scale mid-level ridging building across the eastern Pacific, toward the North American coast, later today through tonight. As this occurs, a vigorous downstream short wave trough appears likely to rapidly dig inland of the Pacific Northwest coast by early this evening, and into the Rockies by daybreak Wednesday. Another perturbation is expected to continue digging within a separate branch, across the subtropical eastern Pacific to the west of Baja. Models indicate that flow farther downstream will remain broadly confluent east of the Great Plains through the Atlantic Seaboard. Beneath this regime, although it may continue to slowly weaken, cold surface ridging appears likely to persist across much of the southeastern U.S. into the northwest Gulf coast vicinity. Weak moisture return may commence above this air mass across the lower Rio Grande Valley into parts of the southern Great Plains, and perhaps near southern Atlantic coastal areas. Otherwise, appreciable boundary-layer moistening may remain confined to parts of southeastern Florida, as northeasterly to easterly near surface flow is maintained across the peninsula and northern Gulf of Mexico. ...Pacific Northwest... Low-level moistening maintained in the wake of an inland advancing surface front may be sufficient to contribute to weak boundary-layer destabilization, in the presence of substantive post-frontal mid-level cooling (including 500 mb temps falling to around or below -26C). It appears that this may become supportive of low-topped convection capable of producing at least some lightning across southern Washington/northern Oregon coastal areas by 21-22Z, near or in the wake of a small but rather intense mid-level jet streak (including 70-90+ kt around 500 mb) migrating inland. Given forecast soundings exhibiting 30-40+ kt westerly mean flow in the lowest few kilometers above ground level, locally strong wind gusts aided by downward momentum transfer may be possible in the more vigorous showers/storms. However, activity is still expected to generally remain below severe limits. ..Kerr/Thornton.. 11/22/2022 Read more

No watches are valid as of Mon Nov 21 17:24:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Nov 21 17:24:02 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1103 AM CST Mon Nov 21 2022 Valid 221200Z - 231200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms are not expected on Tuesday. ...Synopsis... Northern stream is expected to remain progressive on Tuesday. A lead shortwave trough will move quickly across the Upper Midwest and Great Lakes while another slightly stronger shortwave moves across the Pacific Northwest/British Columbia and northern Rockies into the northern High Plains. The surface pattern east of the Rockies will be dominated by high pressure, with resulting offshore flow mitigating any potential moisture return. The only exception is across the FL Peninsula, where modest low-level moisture will remain in place. Isolated thunderstorms are possible across the peninsula as easterly low-level flow promotes sea-breeze activity. Modest directional shear is forecast, with low-level easterly flow veering to westerly aloft, but speeds will be low. A strong storm or two is possible, but this shear should limit updraft strength and duration, limiting the overall severe potential. ..Mosier.. 11/21/2022 Read more

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.