Severe Storms

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0221 PM CDT Mon Oct 02 2023 Valid 031200Z - 041200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 10/02/2023 .PREV DISCUSSION... /ISSUED 0220 AM CDT Mon Oct 02 2023/ ...Synopsis... The upper low over parts of the Southwest is forecast to weaken further D2/Tuesday as it begins to shift eastward over the Southern Rockies/Plains. Flow aloft along the eastern periphery of the low will also weaken, though a belt of somewhat enhanced flow should remain over parts of far southern NM. At the surface, a cooler air mass is expected in the wake of a weak cold front as cloud cover and precipitation chances increase. A few pockets of lower humidity are still possible, but RH recoveries will generally improve overnight. Daytime RH values should also remain higher, at roughly 20-30%. While a few hours of gusty winds may occasionally overlap with areas of lower RH through the day, moderating temperatures, the chance for precipitation, and limited overlap with dry fuels suggest the potential for sustained elevated or critical fire-weather conditions is low. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Oct 1 22:33:02 UTC 2023.

No Mesoscale Discussions are in effect as of Sun Oct 1 22:33:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0441 PM CDT Sun Oct 01 2023 Valid 031200Z - 091200Z A large upper-trough currently over the Great Basin will continue eastward into the Plains early this coming week. The trough will generally lose amplitude with time and upper-level wind fields will weaken as well. By late next week, ridging will build into the West with the upper trough strengthening over the Upper Midwest. At the surface, a cold front will move through the Plains and eventually the Southeast and East. Surface high pressure will fill in behind the front. Cooler temperatures and precipitation will occur across a broad area as the front and upper trough progress east. This should greatly limit fire weather concerns within the Plains. High pressure filling into the Great Basin will promote some potential for offshore flow in southern California, but fuel receptiveness will mitigate fire weather risk. Overall, potential for critical fire weather during the period is expected to remain low. ..Wendt.. 10/01/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0259 PM CDT Sun Oct 01 2023 Valid 012000Z - 021200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SOUTHERN HIGH PLAINS... ...SUMMARY... Isolated large hail and locally strong to severe wind gusts will be possible until around 10 PM MDT in eastern New Mexico to far west Texas. ...20Z Update... The Marginal Risk has been expanded slightly northeastward across the TX/OK Panhandles into extreme southwest KS, downstream of developing storms north/west of Amarillo. Otherwise, no changes have been made to the severe probabilities. One strong storm has recently developed across Lincoln County, NM, with isolated supercell development still possible later this afternoon into this evening from eastern NM into far west TX. See the previous discussion below for more information, and MCD 2207 regarding the short-term severe threat in eastern NM. ..Dean.. 10/01/2023 .PREV DISCUSSION... /ISSUED 1127 AM CDT Sun Oct 01 2023/ ...Eastern NM and far west TX... A plume of boundary-layer dewpoints in the 50s to low 60s has enveloped much of eastern NM into west TX and will support a more buoyant air mass later this afternoon relative to yesterday. But the presence of low-level stratus this morning has slowed boundary-layer heating and will temper MLCAPE values to an extent. Still, a confined corridor of 1500-2500 J/kg MLCAPE should develop where cloud breaks are evident across southeast NM into the TX Trans-Pecos. Isolated to scattered thunderstorms are most probable over the higher terrain in this region and should regenerate from mid-afternoon through at least early evening. While deep-layer vertical shear should be modest across much of the area, a narrow zone of effective bulk shear approaching 30 kts should develop in a portion of east-central/southeast NM where low-level south-southeasterlies persist beneath moderate mid-level southwesterlies. This should yield potential for a few slow-moving supercells, although there is uncertainty in just how warm the boundary layer will actually get where the better shear environment exists. Even so, isolated large hail and locally strong gusts should be the main threats, with localized severe gusts tending to focus farther south into the Trans-Pecos where surface heating is greater. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0214 PM CDT Sun Oct 01 2023 Valid 021200Z - 031200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 10/01/2023 .PREV DISCUSSION... /ISSUED 0154 AM CDT Sun Oct 01 2023/ ...Synopsis... The upper low centered over the Great Basin and Southwest is forecast to slowly weaken through the remainder of the weekend into the early work week. As the upper low slowly breaks down, flow aloft will also become increasingly meridional and weaken with time. As the air mass slowly cools from the advancing cold core and increasing precipitation/cloud cover, the overlap of strong winds and low RH will constrict. Isolated pockets of dry and breezy conditions may persist over more sheltered areas of the Southwest across western NM and far eastern AZ. However, the coverage and the temporal continuity of sustained elevated fire-weather conditions is unlikely to reach elevated criteria D2/Monday. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sat Sep 30 22:13:02 UTC 2023.

MD 2206 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF EASTERN NEW NM AND SOUTHERN CO INTO THE FAR WESTERN OK/TX PANHANDLES.
Mesoscale Discussion 2206 NWS Storm Prediction Center Norman OK 0456 PM CDT Sat Sep 30 2023 Areas affected...portions of eastern new NM and southern CO into the far western OK/TX Panhandles. Concerning...Severe potential...Watch unlikely Valid 302156Z - 010000Z Probability of Watch Issuance...5 percent SUMMARY...Scattered high-based thunderstorms may pose a risk for occasional damaging gusts and/or small hail through this evening. Storm organization potential appears low, and a WW is not anticipated. DISCUSSION...As of 2145 UTC, regional radar and satellite analysis showed scattered thunderstorms ongoing to the east of a broad upper low centered over the Desert Southwest. Over the last hour, these storms have gradually increased in coverage and intensity with a few stronger reflectively cores emerging over parts of east/northeastern NM. On the fringes of the upper-level cold core, surface dewpoints in the mid 40s F were supporting 500-750 J/kg of MLCAPE which should be sufficient for occasional stronger updrafts. Vertical shear remains modest with much of the stronger southerly flow aloft remaining to the west. However, this should increase with time and 25-30 kt of effective shear may support occasional updraft organization into sustained multicell clusters and or weak supercells. With cloud bases remaining relatively high (at or above 2 km) damaging outflow winds are possible with the more organized storms/clusters through this evening. A few instances of marginally severe hail are also possible given relatively steep mid-level lapse rates and the potential for a few transient supercell structures. Observational trends and recent hi-res guidance suggest scattered storms may pose an occasional severe threat over the next couple of hours into this evening. While flow aloft will continue to increase, nocturnal cooling of the relatively dry boundary layer will likely favor a gradual weakening after dark. Given the uncertainty on the longevity and organization of the potential severe threat, a WW is unlikely at this time. ..Lyons/Bunting.. 09/30/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...AMA...PUB...ABQ...EPZ... LAT...LON 33170560 33550645 34520697 35060708 35540688 36360608 37440491 37820432 38010311 37870262 37240218 36100254 34690348 33530440 33220542 33170560 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0346 PM CDT Sat Sep 30 2023 Valid 021200Z - 081200Z A broad mid-upper-level trough over the Great Basin this weekend will begin to move into the central/southern Plains by midweek. As this trough moves east, a cold front will move south-southeast through much of the Plains bringing with it an increase in precipitation and cooler, drier air. Although breezy conditions will develop across portions of the Plains ahead of the ejecting trough and approaching cold front, relative humidity should remain sufficiently high to preclude widespread fire weather concerns. ..Marsh.. 09/30/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0255 PM CDT Sat Sep 30 2023 Valid 302000Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHWEST THIS AFTERNOON AND EVENING.... ...SUMMARY... Isolated severe wind gusts will be possible across parts of the Southwest, mainly from late afternoon into this evening. Storms have started to form over the mountains from central New Mexico to south-central Colorado. Expect an increase in coverage and intensity of these storms through the afternoon with a threat for isolated large hail and severe wind gusts. Instability remains quite weak across the Great Basin this afternoon. Weak instability has developed across southern Nevada, beneath the cooling temperatures aloft. However, extensive cloud cover across this area has limited surface heating and any greater instability. Farther south and east, heating is occurring across southern Utah and northern Arizona. However, this region is very dry with dewpoints in the 20s. Nonetheless, there may be adequate heating for a line of thunderstorms to develop from southwest Utah into northwest Arizona and vicinity later this afternoon. ..Bentley.. 09/30/2023 .PREV DISCUSSION... /ISSUED 1117 AM CDT Sat Sep 30 2023/ ...Central/eastern NM to southeast CO... Low to mid-level moisture will gradually increase across most of NM into southeast CO, to the east of an amplified upper trough shifting east from CA to NV. In the wake of weakening morning convection across eastern NM, robust boundary-layer heating will yield a modestly unstable air mass by late afternoon with MLCAPE largely peaking around 1000 J/kg. Scattered late afternoon thunderstorms are expected to develop off the higher terrain of central to eastern NM into southern CO. Amid the peripheral influence of strengthening mid to upper flow associated with the CA/NV trough, modest-moving multicell clusters should evolve and offer a threat for sporadic severe wind gusts centered on 4 to 8 PM MDT. ...Southern Great Basin... Ahead of the aforementioned upper trough, a low-level baroclinic zone will strengthen somewhat as it shifts east this afternoon into tonight. The paucity of low to mid-level moisture within the warm sector ahead of this zone should delay convective initiation until at least early evening and likely confined to the Lower CO Valley vicinity. A slow-moving band of thunderstorms may evolve across northwest AZ to southwest UT along the edge of surface-based instability. Strong low to mid-level flow should compensate for the meager buoyancy and support a threat for sporadic severe wind gusts. Additional convection should form farther west over the Mojave Desert and spread north-northeast into western UT during the evening as mid-level cooling spreads east, but also coinciding with boundary-layer cooling. Localized strong to severe wind gusts and small hail will be possible with this activity before subsiding later tonight. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0215 PM CDT Sat Sep 30 2023 Valid 011200Z - 021200Z No changes needed to the existing forecast. Please see the previous forecast discussion for more information. ..Marsh.. 09/30/2023 .PREV DISCUSSION... /ISSUED 0153 AM CDT Sat Sep 30 2023/ ...Synopsis... The deepening upper low is forecast to gradually cut off from the stronger mid-level westerlies through the remainder of the weekend. As it settles over the Southwest, strong mid-level flow will continue to reside over parts of NM and the High Plains. Gusty winds and low afternoon humidity should support some risk for elevated fire-weather conditions D2/Sunday. ...Portions of NM and AZ... As the upper low begins to cut off, strong mid-level flow along the eastern periphery will linger over parts of the Southwest through the remainder of the weekend. Breezy southerly winds are expected much of the day across western NM and southeastern AZ, with gusts of 20-25 mph likely. While still relatively dry, the air mass beneath the upper low is expected to cool gradually, supporting higher RH recoveries overnight. Pockets of 15-20% RH still appear likely through the afternoon, but the air mass should be moderated by the cooler temperatures. Still, the gusty winds and localized dryness will support several hours of elevated to locally critical fire-weather concerns within dry fuels. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Fri Sep 29 22:21:01 UTC 2023.

MD 2205 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF SOUTHERN AND CENTRAL MN...FAR EASTERN SD/NORTHWEST IA
Mesoscale Discussion 2205 NWS Storm Prediction Center Norman OK 0514 PM CDT Fri Sep 29 2023 Areas affected...portions of southern and central MN...far eastern SD/northwest IA Concerning...Severe potential...Watch unlikely Valid 292214Z - 300015Z Probability of Watch Issuance...20 percent SUMMARY...Isolated hail and or damaging wind gusts are possible with scattered storms along a frontal zone this afternoon/evening. Storm organization and coverage should remain below the need for a weather watch. DISCUSSION...Across parts of the northern Plains and upper Midwest, scattered thunderstorms have slowly intensified along a frontal zone across parts of southwest MN and far eastern SD. Along and south of the front, surface temperatures in the 80s with dewpoints in the mid 60s were supporting 1500-2000 J/kg of MLCAPE. However, much of the warm sector remains capped in the lower levels. So far, storm development has been focused along and immediately north of the warm front where overrunning and mid-level warm advection are supporting 1000-1500 J/kg of MUCAPE. While not overly large, the forcing along the front, moderate buoyancy and mid-level lapse rates of 7-7.5 C/km will likely continue to support a few strong updrafts into this evening. Deep-layer shear of 30-40 kts may favor some storm organization into multicell clusters of elevated supercell structures. Given the storm mode and potential for some organization the primary risk will be for isolated hail and or damaging winds with the strongest storms. Storm coverage and organization are expected to remain relatively limited with the majority of storms staying elevated along and north of the front. Thus, a weather watch appears unlikely though convective trends will be monitored. ..Lyons/Hart.. 09/29/2023 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...MPX...FSD...ABR... LAT...LON 43979448 43649526 43029606 42839651 42889682 43069688 43479679 43899673 44199666 45059631 45589512 45769399 45639324 45329297 45129312 44639350 43979448 Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0342 PM CDT Fri Sep 29 2023 Valid 011200Z - 071200Z A broad and strong upper-level trough will be positioned over the Great Basin this weekend into early next week. This trough will eventually eject into the central/southern Plains by Tuesday into Wednesday. As it progresses east, a cold front will move southeastward through much of the Plains and eventually into the East by the end of next week. Cooler temperatures and precipitation are expected with the front. Fire weather concerns will exist in parts of eastern Arizona into western New Mexico this Sunday. The upper-level trough will not make much eastward progress from Saturday. Winds may be a touch lighter on Sunday as compared to Saturday as the surface low will be positioned farther northeast of the region. How broadly critical RH will be observed is also uncertain, but at least pockets of critical fire weather appear possible. Dry and breezy conditions will likely persist into Monday across the same areas. However, RH reductions become less certain as some upper-level cloud cover is possible and temperatures may be slightly cooler. Areas of breezy conditions are also possible within the Plains as the trough approaches. RH reductions over most areas do not look overly favorable for fire weather concerns. Furthermore, the chance for precipitation will be on the increase as well. By Wednesday, the cold front will be into the southern Plains and cooler temperatures will further mitigate fire weather concerns. ..Wendt.. 09/29/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0240 PM CDT Fri Sep 29 2023 Valid 292000Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE UPPER MIDWEST... ...SUMMARY... Isolated large hail and locally damaging winds will be possible across parts of the Upper Midwest between about 6 PM to 2 AM CDT. ...20Z Update... ...Far Northeast NE to East-Central MN... Overall scenario outlined in the previous discussion remains. Isolated surface-based thunderstorm development is still possible along the cold front pushing southeastward across eastern SD and NE. However, greater thunderstorms potential exists later this evening and overnight as a strengthening low-level jet fosters isentropic ascent along the frontal zone. Weak deep-layer shear should limit updraft intensity and duration, but isolated instance of hail are possible within the first few hours of development. ..Mosier.. 09/29/2023 .PREV DISCUSSION... /ISSUED 1117 AM CDT Fri Sep 29 2023/ ...Northeast NE to east-central MN... Primary categorical change with this outlook is to reorient the spatial extent of the expected threat in the wake of this morning's storms amid above-average consistency in 12Z CAM guidance. Gradual mid-level height rises are expected across the region as a shortwave trough progresses northeast from the Upper Red River Valley across northern ON. Differential boundary-layer heating will reinforce the southwest to northeast baroclinic zone from northeast NE/southeast SD through east-central MN. A storm or two might develop along the southwest flank of this corridor in the early evening where MLCIN is minimized with a conditional threat of marginal severe wind gusts. The more probable scenario is for slightly elevated thunderstorm development to occur after sunset from southwest to east-central MN on the nose of a strengthening low-level jet. Low-level hodographs will favor updraft rotation with initial storms, but a decrease in winds with height along with some reduction in steep lapse rates owing to slow mid-level warming should temper hail magnitudes beyond golf ball size. The longevity of the isolated large hail threat should also be curtailed to around 3-4 hours as storm mode becomes dominated by clusters and instability/buoyancy wanes overnight. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0217 PM CDT Fri Sep 29 2023 Valid 301200Z - 011200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF WESTERN CO EASTERN UT AND SOUTHERN WY... No changes to the ongoing forecast. ..Wendt.. 09/29/2023 .PREV DISCUSSION... /ISSUED 0202 AM CDT Fri Sep 29 2023/ ...Synopsis... The deepening trough over the western CONUS is forecast to continue to strengthen as it overspreads strong mid-level flow across the Great Basin and western Rockies. Enhanced surface winds are likely from NM to WY, along with dry and warm surface conditions. Several hours of elevated to critical fire-weather concerns are likely. ...Western Slope... The upper trough over the western US is forecast to deepen significantly D2/Sat with strong south/southwesterly flow likely over the Rockies. A deepening surface low over the Great Basin, and the increase in mid-level winds will bolster surface winds to 25-30 mph through the afternoon across portions of western CO and southern WY. Along with a moderately strong wind field, dry downslope flow and warm surface temperatures will support afternoon RH values of 12-20%. The best overlap of critical humidity and surface winds appears to be across parts of western CO coincident with the most receptive fuels. Thus, several hours of critical fire-weather conditions are likely D2/Sat afternoon and evening. Though not as strong, gusty surface winds and low humidity are also likely over parts of the Four Corners into western NM. Deep mixing and warm surface temperatures will favor afternoon RH values below 20% within relatively dry fuels. Widespread elevated to locally critical conditions appear possible over parts of NM and AZ. ...High Plains... To the east across the central High Plains, gusty southerly winds of 15-20 mph and afternoon humidity below 25% are possible D2/Sat. While forecast confidence is relatively low given various model differences, a few hours of dry and breezy conditions may support locally elevated fire concerns across parts of eastern CO and far western KS where fuels remain relatively dry. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Thu Sep 28 23:16:02 UTC 2023.

No Mesoscale Discussions are in effect as of Thu Sep 28 23:16:02 UTC 2023.

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0455 PM CDT Thu Sep 28 2023 Valid 301200Z - 061200Z ...Days 3-4/Saturday-Sunday... A highly amplified large-scale trough will move slowly eastward over the western CONUS on Days 3-4/Saturday-Sunday. Preceding this feature, a belt of strong deep-layer south-southwesterly flow will overspread a dry air mass from parts of the Southwest into the eastern Great Basin and central Rockies. Ample boundary-layer mixing into the strong deep-layer flow, coupled with a tightening surface pressure gradient, will yield an expansive area of 20-25+ mph sustained south-southwesterly surface winds (with higher gusts) amid 10-15 percent RH over the aforementioned areas on Day 3/Saturday. Strong surface winds will persist across the same areas on Day 4/Sunday (with a slight eastward shift in the strongest winds), though substantial RH reductions will generally be confined to portions of the Southwest. Widespread elevated to locally critical conditions are expected for both days, with the primary limiting factor being marginally receptive fuels where the best overlap of strong winds and low RH is expected. Father east, persistent lee troughing will favor breezy southerly surface winds over portions of the central and southern Plains each day. Along the western edge of the richer boundary-layer moisture return, a slim overlap of the strong winds and low RH is possible over portions of the central and southern High Plains. However, the potential for critical conditions appears too low for probabilities at this time. ...Days 5-8/Monday-Thursday... The large-scale trough and related enhanced flow aloft will move gradually eastward across the central CONUS. Similar to Day 4/Sunday, breezy/gusty southerly surface winds (albeit slightly weaker) are expected over the central/southern Plains on Day 5/Monday, with similar uncertainties regarding RH reductions. Thereafter, a cold front and related precipitation should overspread the Great Plains, generally reducing the fire-weather risk across the CONUS. ..Weinman.. 09/28/2023 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0245 PM CDT Thu Sep 28 2023 Valid 291200Z - 301200Z ...Central and Southern Plains... An Elevated area was added from parts of west-central KS south-southwestward into portions of northeast NM. From KS into northwest OK, 20-25 mph sustained southerly surface winds (with gusts upwards of 35 mph) will primarily support a wind-driven fire risk given marginal RH reductions (25-30 percent) along the western edge of the more-substantial boundary-layer moisture return. Given the strong/gusty winds, lower to middle 90s temperatures, and somewhat marginal RH/fuels, Elevated highlights are warranted. From portions of the OK/TX Panhandles into northeast NM, the combination of 10-15 percent RH and 15-20 mph west-southwesterly surface winds will also favor locally elevated fire-weather conditions. Elsewhere, only minor changes were made based on the latest high-resolution guidance. For details, see the previous discussion below. ..Weinman.. 09/28/2023 .PREV DISCUSSION... /ISSUED 0119 AM CDT Thu Sep 28 2023/ ...Synopsis... Elevated fire weather conditions are expected across parts of southern WY into adjacent areas of UT and CO Friday afternoon. Early-morning water-vapor imagery across the northeast Pacific depicts two shortwave impulses embedded within the mean northwesterly flow. The second of these is expected to amplify over the next 48 hours along the West Coast, resulting in strengthening mid-level southwesterly flow from the lower CO River Valley into the central Rockies. This flow regime will also maintain dry conditions across the Great Basin. Consequently, dry and windy conditions are forecast across a large swath of the Great Basin Friday afternoon. Recent ensemble guidance suggests elevated to locally critical fire weather conditions are probable, but may be patchy in nature across the region. This, combined with generally unreceptive fuels for most locations, limits confidence in the coverage of the fire weather threat. However, portions of southern WY, northeast UT, and northwest CO should see favorable overlap of elevated conditions with dry fuels - especially after several previous days of similarly dry/windy weather. Elsewhere, windy conditions are expected across KS and southern NE as a lee trough continues to strengthen. While 20+ mph winds are expected, confidence in sub-25% RH is limited due to persistent moisture advection from the south. Trends will continue to be monitored for fuel dryness and the quality of moisture return. ...Please see www.spc.noaa.gov/fire for graphic product... Read more