SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0150 AM CDT Sun Sep 15 2024 Valid 151200Z - 161200Z ...Synopsis... Preceding an amplifying large-scale trough over the West Coast, enhanced deep-layer meridional flow will overspread the Great Basin, while a related surface cyclone evolves over northern NV. Deep boundary-layer mixing into the enhanced flow aloft, along with a tightening pressure gradient peripheral to the surface cyclone, will yield 20-25 mph sustained southerly surface winds and 15-20 percent RH over southern/central NV. Given modestly receptive fuels here, elevated fire-weather conditions are expected during the afternoon. Additionally, large-scale ascent accompanying the amplifying midlevel trough will promote a mix of wet/dry thunderstorms across the northern Great Basin/Intermountain West. While quick storm motions and limited precipitation with some of this activity could yield a risk of lightning-induced ignitions, marginal fuels should generally limit the threat. Over the southern High Plains, breezy/gusty southerly surface winds will develop amid a warm/dry boundary layer near a lee trough during the afternoon. This will favor a few hours of elevated fire-weather conditions. ..Weinman.. 09/15/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE EASTERN GREAT BASIN TO FOUR CORNERS...THE RED RIVER VALLEY OF THE NORTH...AND EASTERN NC... ...SUMMARY... On Monday, sporadic severe gusts and marginally severe hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated, marginally severe storms are possible over eastern North Dakota into northwest Minnesota during the late afternoon and evening. A low-probability tornado threat may develop over eastern North Carolina. ...Eastern Great Basin to the Four Corners... An amplified mid-level low near the Bay Area at 12Z Monday should initially move east before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection should be ongoing Monday morning immediately ahead of the mid-level low and separately in the low-level warm/moist conveyor over the Four Corners region. Greater boundary-layer heating should occur between these two regimes across eastern NV into UT, west of the Wasatch Range. Despite meager MLCAPE, the deepening boundary layer amid a strengthening meridional wind profile should yield efficient downward mixing. This will be further augmented by evaporatively cooled downdraft accelerations and promote a threat for sporadic severe gusts. Farther southeast, a more southwesterly mid to upper-flow regime should yield hodograph elongation, supporting a few splitting supercells. Warmer mid-level temperatures and correspondingly weaker lapse rates will temper parcel acceleration to an extent, but this may be offset by somewhat higher PW values. Marginal severe hail/gusts will be possible. ...Eastern ND to northwest MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of D1 central High Plains convection and gradually progress northeast towards the Red River Valley. In conjunction with the northern nose of a strengthening central to northern Great Plains low-level jet, a focused corridor for regenerative thunderstorm development may occur during the late afternoon and evening. Some low-level hodograph enlargement should support a predominantly clustered convective mode, with transient supercell structures possible. An isolated, lower-end severe hail/wind threat may develop, and a brief tornado is also possible. ...Coastal NC... While guidance consensus increasingly favors offshore cyclogenesis, the amplitude of this development along with timing of inland progression remain quite varied for a D2 forecast. The 00Z NAM and some of the 18Z ECMWF ENS members suggest particularly robust deepening will occur. The more aggressive scenarios would yield substantial enlargement of low-level hodographs, likely becoming coupled with a narrow swath of high theta-e air spreading west-northwestward from the Gulf Stream. Given the potential range of scenarios from nil threat to multiple tornadic supercells, a low-probability tornado highlight appears warranted. ..Grams.. 09/15/2024 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Sun Sep 15 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS IN THE EASTERN GREAT BASIN TO FOUR CORNERS...THE RED RIVER VALLEY OF THE NORTH...AND EASTERN NC... ...SUMMARY... On Monday, sporadic severe gusts and marginally severe hail will be possible during the afternoon to early evening across parts of the eastern Great Basin to Four Corners. Isolated, marginally severe storms are possible over eastern North Dakota into northwest Minnesota during the late afternoon and evening. A low-probability tornado threat may develop over eastern North Carolina. ...Eastern Great Basin to the Four Corners... An amplified mid-level low near the Bay Area at 12Z Monday should initially move east before curling northeast Monday night towards the NV/UT/ID border area. This will occur in response to a strong mid-level jet translating through the basal portion of the large-scale trough across the Desert Southwest into the eastern Great Basin. Convection should be ongoing Monday morning immediately ahead of the mid-level low and separately in the low-level warm/moist conveyor over the Four Corners region. Greater boundary-layer heating should occur between these two regimes across eastern NV into UT, west of the Wasatch Range. Despite meager MLCAPE, the deepening boundary layer amid a strengthening meridional wind profile should yield efficient downward mixing. This will be further augmented by evaporatively cooled downdraft accelerations and promote a threat for sporadic severe gusts. Farther southeast, a more southwesterly mid to upper-flow regime should yield hodograph elongation, supporting a few splitting supercells. Warmer mid-level temperatures and correspondingly weaker lapse rates will temper parcel acceleration to an extent, but this may be offset by somewhat higher PW values. Marginal severe hail/gusts will be possible. ...Eastern ND to northwest MN... With the primary upper-level trough displaced well to the west, deep-layer shear will remain weak across much of the Great Plains. However, most guidance suggests an MCV will emanate out of D1 central High Plains convection and gradually progress northeast towards the Red River Valley. In conjunction with the northern nose of a strengthening central to northern Great Plains low-level jet, a focused corridor for regenerative thunderstorm development may occur during the late afternoon and evening. Some low-level hodograph enlargement should support a predominantly clustered convective mode, with transient supercell structures possible. An isolated, lower-end severe hail/wind threat may develop, and a brief tornado is also possible. ...Coastal NC... While guidance consensus increasingly favors offshore cyclogenesis, the amplitude of this development along with timing of inland progression remain quite varied for a D2 forecast. The 00Z NAM and some of the 18Z ECMWF ENS members suggest particularly robust deepening will occur. The more aggressive scenarios would yield substantial enlargement of low-level hodographs, likely becoming coupled with a narrow swath of high theta-e air spreading west-northwestward from the Gulf Stream. Given the potential range of scenarios from nil threat to multiple tornadic supercells, a low-probability tornado highlight appears warranted. ..Grams.. 09/15/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Sep 15 2024 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Central and Northern High Plains... An upper-level low will move southward along the West Coast today, as southwest mid-level flow remains over much of the western third of the U.S. A subtle shortwave trough is forecast to move northeastward through the central Rockies. Ahead of the trough, a moist airmass will be in place in the central and northern Plains, where surface dewpoints will mostly be from the upper 50s to the mid 60s F. As surface temperatures warm, moderate instability is expected to develop over much of this airmass. MLCAPE is forecast to peak in the 2000 to 3000 J/kg range in areas that heat up the most. The instability axis is forecast to be located from northwest Kansas northward into western Nebraska and southwest South Dakota by mid to late afternoon. At this time, RAP forecast soundings near the instability axis have low to mid-level lapse rates exceeding 8 C/km, and enough deep-layer shear for a marginal severe threat. Isolated severe gusts and hail will be possible with the stronger cells, mainly during the late afternoon and early evening. ..Broyles/Weinman.. 09/15/2024 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Sep 15 2024 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Thunderstorms capable of isolated severe gusts and hail will be possible today across parts of the central and northern High Plains. ...Central and Northern High Plains... An upper-level low will move southward along the West Coast today, as southwest mid-level flow remains over much of the western third of the U.S. A subtle shortwave trough is forecast to move northeastward through the central Rockies. Ahead of the trough, a moist airmass will be in place in the central and northern Plains, where surface dewpoints will mostly be from the upper 50s to the mid 60s F. As surface temperatures warm, moderate instability is expected to develop over much of this airmass. MLCAPE is forecast to peak in the 2000 to 3000 J/kg range in areas that heat up the most. The instability axis is forecast to be located from northwest Kansas northward into western Nebraska and southwest South Dakota by mid to late afternoon. At this time, RAP forecast soundings near the instability axis have low to mid-level lapse rates exceeding 8 C/km, and enough deep-layer shear for a marginal severe threat. Isolated severe gusts and hail will be possible with the stronger cells, mainly during the late afternoon and early evening. ..Broyles/Weinman.. 09/15/2024 Read more

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 0819 PM CDT Sat Sep 14 2024 Valid 150100Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS... CORRECTED FOR FLIPPED THUNDER LINE ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail will be possible this evening over parts of the central and northern Plains. ...Central and Northern Plains... The latest water vapor imagery shows a shortwave trough over the Dakotas extending southward into northern Nebraska. Along this corridor, the RAP has a two distinct vorticity maxima analyzed. At the surface, a trough is located in the northern High Plains, and a moist airmass is present over much of the central and northern Plains. Surface dewpoints within this moist airmass vary from the mid 50s to mid 60s F. The RAP suggests that moderate instability is present from west-central Nebraska into parts of the Dakotas, where isolated to scattered thunderstorms are ongoing. The North Platte 00Z sounding has the best severe environment regionally, with MLCAPE near 1500 J/kg, and 0-3 km shear around 35 knots. On this sounding, the average low to mid-level lapse rate is near 7.5 C/km. This, along with instability and shear suggest that a marginal severe threat will likely continue for a few more hours. Isolated severe gusts and hail will be possible with rotating cells. The threat is expected to diminish during the mid to late evening as instability decreases across the region. ..Broyles.. 09/15/2024 Read more

No Mesoscale Discussions are in effect as of Sat Sep 14 21:33:02 UTC 2024.

No watches are valid as of Sat Sep 14 21:33:02 UTC 2024.

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sat Sep 14 2024 Valid 142000Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail will be possible over parts of the north-central Plains this afternoon and evening. ...20z Update... Minimal changes have been made to trim the northern Plains Marginal behind ongoing convection, otherwise the Day 1 Convective Outlook remains on track. See previous discussion below for more information. ..Thornton/Gleason.. 09/14/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sat Sep 14 2024/ ...Northern/Central Plains... Modest ascent associated with a weak shortwave trough over eastern WY is encouraging towering cu and recent thunderstorm initiation across parts of western/central NE late this morning. This convective development is also occurring along/near a weak surface trough. Even though large-scale ascent is expected to remain fairly modest across much of the northern/central Plains today in the wake of a more prominent upper trough moving northeastward over central Canada, most guidance still shows potential for isolated to scattered thunderstorms developing this afternoon across parts of northwest NE into western/central SD along/near the surface trough. With modest/shallow low-level moisture in place, but steep mid-level lapse rates per 12Z LBF/UNR soundings, robust daytime heating will likely support around 1000-2000 J/kg of MLCAPE by mid afternoon. West-southwesterly flow at mid levels is forecast to be only modestly enhanced by the passing shortwave trough. Still, a veering and gradually strengthening wind profile with height through mid levels should support around 25-35 kt of deep-layer shear. Occasional hail may occur with any marginal supercells that can initially develop, although tendency for clustering and outflow interactions may lead to an isolated severe wind threat with time late this afternoon and early evening. The overall severe risk should quickly wane this evening with the loss of daytime heating. ...Southern High Plains... At least isolated high-based thunderstorms should develop this afternoon across parts of the TX Panhandle and vicinity along/east of a weak surface front/trough. With a deeply mixed boundary layer expected with daytime heating, occasional strong/gusty downdraft winds may occur with the more robust cores. However, weak deep-layer shear should keep the overall severe wind threat rather isolated. ...East Texas into Southern Louisiana/Mississippi... Isolated to widely scattered thunderstorms may develop along a weak front from parts of east TX into southern LA/MS later this afternoon. This activity would occur on the back side of a remnant mid-level circulation over the Mid-South. While modestly enhanced mid-level flow will be present, the potential for a more organized severe wind threat appears too low to include probabilities at this time. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sat Sep 14 2024 Valid 142000Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail will be possible over parts of the north-central Plains this afternoon and evening. ...20z Update... Minimal changes have been made to trim the northern Plains Marginal behind ongoing convection, otherwise the Day 1 Convective Outlook remains on track. See previous discussion below for more information. ..Thornton/Gleason.. 09/14/2024 .PREV DISCUSSION... /ISSUED 1128 AM CDT Sat Sep 14 2024/ ...Northern/Central Plains... Modest ascent associated with a weak shortwave trough over eastern WY is encouraging towering cu and recent thunderstorm initiation across parts of western/central NE late this morning. This convective development is also occurring along/near a weak surface trough. Even though large-scale ascent is expected to remain fairly modest across much of the northern/central Plains today in the wake of a more prominent upper trough moving northeastward over central Canada, most guidance still shows potential for isolated to scattered thunderstorms developing this afternoon across parts of northwest NE into western/central SD along/near the surface trough. With modest/shallow low-level moisture in place, but steep mid-level lapse rates per 12Z LBF/UNR soundings, robust daytime heating will likely support around 1000-2000 J/kg of MLCAPE by mid afternoon. West-southwesterly flow at mid levels is forecast to be only modestly enhanced by the passing shortwave trough. Still, a veering and gradually strengthening wind profile with height through mid levels should support around 25-35 kt of deep-layer shear. Occasional hail may occur with any marginal supercells that can initially develop, although tendency for clustering and outflow interactions may lead to an isolated severe wind threat with time late this afternoon and early evening. The overall severe risk should quickly wane this evening with the loss of daytime heating. ...Southern High Plains... At least isolated high-based thunderstorms should develop this afternoon across parts of the TX Panhandle and vicinity along/east of a weak surface front/trough. With a deeply mixed boundary layer expected with daytime heating, occasional strong/gusty downdraft winds may occur with the more robust cores. However, weak deep-layer shear should keep the overall severe wind threat rather isolated. ...East Texas into Southern Louisiana/Mississippi... Isolated to widely scattered thunderstorms may develop along a weak front from parts of east TX into southern LA/MS later this afternoon. This activity would occur on the back side of a remnant mid-level circulation over the Mid-South. While modestly enhanced mid-level flow will be present, the potential for a more organized severe wind threat appears too low to include probabilities at this time. Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sat Sep 14 2024 Valid 161200Z - 221200Z A broad mid-level trough, with multiple embedded impulses, will amplify while gradually translating eastward from the West Coast to the Plains states through the upcoming week. Rainfall should accompany the passing mid-level trough across the Interior West through early parts of the week. Ahead of the mid-level trough, patches of overlapping dry and breezy conditions may develop along parts of the High Plains through Day 5/Wednesday. These conditions are too localized to address with Critical probabilities this outlook, though Elevated highlights may be introduced by Days 1-2. A dry low-level air mass should linger over parts of the Ohio Valley through the middle of the upcoming week. Surface high pressure across the Northeast will encourage dry easterly flow atop receptive fuels over portions of Indiana into Ohio and surrounding areas. Medium-range guidance consensus suggests that surface winds should not be overly strong, so any fire weather highlights that are added would probably take place in the Days 1-2 time frame if areas of locally higher gusts becomes apparent in short-range guidance. ..Squitieri.. 09/14/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0252 PM CDT Sat Sep 14 2024 Valid 161200Z - 221200Z A broad mid-level trough, with multiple embedded impulses, will amplify while gradually translating eastward from the West Coast to the Plains states through the upcoming week. Rainfall should accompany the passing mid-level trough across the Interior West through early parts of the week. Ahead of the mid-level trough, patches of overlapping dry and breezy conditions may develop along parts of the High Plains through Day 5/Wednesday. These conditions are too localized to address with Critical probabilities this outlook, though Elevated highlights may be introduced by Days 1-2. A dry low-level air mass should linger over parts of the Ohio Valley through the middle of the upcoming week. Surface high pressure across the Northeast will encourage dry easterly flow atop receptive fuels over portions of Indiana into Ohio and surrounding areas. Medium-range guidance consensus suggests that surface winds should not be overly strong, so any fire weather highlights that are added would probably take place in the Days 1-2 time frame if areas of locally higher gusts becomes apparent in short-range guidance. ..Squitieri.. 09/14/2024 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0217 PM CDT Sat Sep 14 2024 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE GREAT BASIN INTO THE FOUR CORNERS REGION... ...SUMMARY... Isolated severe gusts and small to marginally severe hail will be possible on Monday afternoon to early evening across parts of the eastern Great Basin to Four Corners. ...Synopsis... The upper-level trough currently in place across the northeastern Pacific is forecast to amplify over the next 24-72 hours as it migrates southward along the West Coast and eventually into the Great Basin. As this occurs, an attendant mid-level jet streak will pivot into the interior West. The combination of increasing ascent and strengthening mid/upper-level winds will support isolated to scattered strong to severe thunderstorms across parts of the Great Basin and Four Corners. To the east across the Plains, surface pressure falls will become increasingly concentrated across the central to northern High Plains, which will maintain a moisture return regime. Weak ascent over a broadening warm sector will support isolated to widely scattered thunderstorm chances. ...Great Basin/Four Corners... Forecast guidance continues to show reasonably good agreement in strengthening wind fields across NV into UT and AZ by peak heating Monday as the mid/upper jet noses into the region. Mid-level lapse rates will steepen through the day ahead of the approaching wave, which, despite very modest moisture content, should support adequate buoyancy for convection. Deep, well-mixed boundary layers will facilitate efficient downward mixing of strong mid-level flow, which will likely be augmented by evaporatively-cooled downdraft accelerations. Consequently, the probability for strong to severe wind gusts appears higher and somewhat more concentrated compared to preceding days. Portions of the Four Corners region may also see a large hail threat given elongated wind profiles and slightly better buoyancy due to an influx of low/mid-level moisture from the Gulf of California. ...Central to northern Plains... Northward moisture return is expected to persist through Monday evening as a lee cyclone becomes more consolidated across the central to northern High Plains. With the primary upper-level trough displaced well to the west, synoptic-scale ascent will remain weak across the Great Plains region. However, signals for thunderstorm development within a modest warm-advection regime across ND and along the lee trough over parts of central/western KS into far northwest OK are noted in recent solutions. Predictability in either scenario is too limited to warrant risk probabilities, but the convective parameter space across both ND and KS/OK appears conducive for a conditional severe threat. ...Coastal North Carolina... A low off the Carolina coast is forecast to gradually intensify/organize over the next 72 hours, though forecast uncertainty regarding its exact evolution remains very high (see the latest NHC forecast discussion for additional details). However, a few solutions, notably recent GFS and NAM runs, suggest the low will migrate inland across the Carolinas during the day Monday. As this occurs, a narrow swath of high theta-e air will span from the NC coast into eastern NC and perhaps southeast VA. Wind profiles within this swath may feature strong low-level helicity that could support some tornado threat given sufficient buoyancy for deep convection. Confidence in this scenario remains very limited, but forecast trends will be monitored. ..Moore.. 09/14/2024 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0157 PM CDT Sat Sep 14 2024 Valid 151200Z - 161200Z The previous forecast remains generally on track. The main change to the Day 2 Fire Weather Outlook update was to add Elevated highlights to portions of the southern High Plains. Across portions of the northwestern Texas Panhandle and adjacent areas to the north, initially dry southerly surface flow (driven by lee troughing) will promote 15 mph sustained winds amid 15-20 percent RH on Sunday afternoon. Fuels in this region are modestly dry, warranting the addition of fire weather highlights. A mix of wet and dry thunderstorms is possible across portions of northeastern Nevada into Idaho during the afternoon as well. However, the marginal receptiveness of fuels, along with the wet/dry thunderstorm mix, suggests that isolated dry thunderstorm highlights are not currently needed. ..Squitieri.. 09/14/2024 .PREV DISCUSSION... /ISSUED 0145 AM CDT Sat Sep 14 2024/ ...Synopsis... Ahead of an amplifying large-scale trough over the West Coast, enhanced deep-layer meridional flow will overspread a diurnally deepening boundary layer (15-20 percent RH) over portions of the southern Great Basin. This, coupled with a tightening pressure gradient along the southern periphery of an evolving surface cyclone, will yield 20-25 mph sustained southerly surface winds. These winds will overlap the lowest RH over portions of southern NV, and given modestly receptive fuels here, elevated fire-weather conditions are expected. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 2067 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PORTIONS OF WESTERN AND CENTRAL SOUTH DAKOTA
Mesoscale Discussion 2067 NWS Storm Prediction Center Norman OK 0116 PM CDT Sat Sep 14 2024 Areas affected...portions of western and central South Dakota Concerning...Severe potential...Watch unlikely Valid 141816Z - 142015Z Probability of Watch Issuance...20 percent SUMMARY...Isolated thunderstorms -- the strongest of which may produce strong/damaging wind gusts and possibly severe-caliber hail -- are expected from parts of western and central South Dakota. The very isolated nature of the risk anticipated at this time should preclude the need for WW issuance. DISCUSSION...Latest radar loop shows isolated, vigorous storms east of the Black Hills area, with the strongest cells moving northeastward across the Haakon/Jackson County area at this time. The convection is ongoing within an environment featuring modestly increasing/veering flow with height, providing shear sufficient for at least multicell organization. Though CAPE will remain limited due to the dry boundary layer (around 1000 J/kg mixed-layer CAPE will prevail across the area), a deep sub-cloud layer has evolved in conjunction with diurnal heating. As such, sub-cloud evaporation -- and thus potential for acceleration of the downdrafts -- suggests that a few stronger/potentially severe gusts will be possible. However, with storms expected to remain isolated, severe-weather coverage is expected to remain insufficient to require WW consideration. ..Goss/Gleason.. 09/14/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...ABR...UNR... LAT...LON 45440172 44300327 43030229 43170131 43800026 44659929 45330089 45440172 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sat Sep 14 2024 Valid 141700Z - 151200Z The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 09/14/2024 .PREV DISCUSSION... /ISSUED 0144 AM CDT Sat Sep 14 2024/ ...Synopsis... A midlevel jet streak will cross the northern Rockies today, encouraging lee troughing along the northern/central High Plains. Over portions of WY, 15-20 mph sustained west-southwesterly surface winds and 10-15 percent RH will develop in response to the lee troughing and deep boundary-layer mixing into the enhanced flow aloft. Given modestly receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon. Farther west, breezy southerly surface winds are expected amid 15-20 percent RH across portions of the southern Great Basin -- within the base of a gradually amplifying large-scale trough. While locally elevated fire-weather conditions are possible, a lack of stronger sustained surface winds should limit the overall fire-weather risk. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sat Sep 14 2024 Valid 141700Z - 151200Z The previous forecast (see below) remains on track, with no changes or additions made. ..Squitieri.. 09/14/2024 .PREV DISCUSSION... /ISSUED 0144 AM CDT Sat Sep 14 2024/ ...Synopsis... A midlevel jet streak will cross the northern Rockies today, encouraging lee troughing along the northern/central High Plains. Over portions of WY, 15-20 mph sustained west-southwesterly surface winds and 10-15 percent RH will develop in response to the lee troughing and deep boundary-layer mixing into the enhanced flow aloft. Given modestly receptive fuels across the area, elevated fire-weather conditions are expected during the afternoon. Farther west, breezy southerly surface winds are expected amid 15-20 percent RH across portions of the southern Great Basin -- within the base of a gradually amplifying large-scale trough. While locally elevated fire-weather conditions are possible, a lack of stronger sustained surface winds should limit the overall fire-weather risk. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Sat Sep 14 2024 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Isolated strong to severe thunderstorms are possible Sunday afternoon and evening across parts of the central High Plains. ...Synopsis... An upper-level trough currently residing over the northeastern Pacific is forecast to deepen substantially over the next 48 hours along the West Coast. This will establish a broad swath of strengthening south/southwesterly flow across the greater Great Basin region into the central/northern Rockies. Low-level moisture return into the central Plains should increase as a lee surface trough slowly deepens in response to the evolving upper-level pattern. The increasing moisture/buoyancy quality may support some intensification of convection as it migrates out of the central Rockies and into the High Plains Sunday afternoon and evening. ...Central High Plains... High-based convection is expected to develop within the central Rockies by mid/late afternoon Sunday as a combination of deep-layer ascent and diurnal warming steepen lapse rates. Isolated thunderstorms are also possible in the vicinity of a deepening surface trough across eastern WY/northeast CO where surface pressure falls are currently expected to be strongest. Forecast guidance suggests that this activity will intensify as it migrates northeast and impinges on the western periphery of the moisture reservoir to the east of the surface trough where MLCAPE values may be as high as 1000-2000 J/kg. While the central High Plains will likely remain displaced from the strongest mid/upper-level flow, 25-30 knot mid-level winds with modest low-level flow should provide sufficient deep-layer shear to support some degree of storm organization with an attendant large hail threat. Additionally, boundary-layer mixing on the edge of the deeper moisture will be adequately deep (mixed-layer LCLs near 2.5 km AGL) to support strong to severe gusts with the more organized cells and/or clusters. ...Great Basin/Four Corners... Increasing broad scale ascent over the Great Basin and Four Corners region should result in isolated to scattered thunderstorm development by late afternoon. While some degree of moisture return is anticipated from the Gulf of California across southern AZ, most regions will remain fairly warm and dry in the low-levels. Such thermodynamic conditions will be conducive for dry downbursts that may be capable of very localized strong to severe gusts. The predictability of where such gusts are most likely across the broader region remains too limited to warrant risk probabilities. ..Moore.. 09/14/2024 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1222 PM CDT Sat Sep 14 2024 Valid 151200Z - 161200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL HIGH PLAINS... ...SUMMARY... Isolated strong to severe thunderstorms are possible Sunday afternoon and evening across parts of the central High Plains. ...Synopsis... An upper-level trough currently residing over the northeastern Pacific is forecast to deepen substantially over the next 48 hours along the West Coast. This will establish a broad swath of strengthening south/southwesterly flow across the greater Great Basin region into the central/northern Rockies. Low-level moisture return into the central Plains should increase as a lee surface trough slowly deepens in response to the evolving upper-level pattern. The increasing moisture/buoyancy quality may support some intensification of convection as it migrates out of the central Rockies and into the High Plains Sunday afternoon and evening. ...Central High Plains... High-based convection is expected to develop within the central Rockies by mid/late afternoon Sunday as a combination of deep-layer ascent and diurnal warming steepen lapse rates. Isolated thunderstorms are also possible in the vicinity of a deepening surface trough across eastern WY/northeast CO where surface pressure falls are currently expected to be strongest. Forecast guidance suggests that this activity will intensify as it migrates northeast and impinges on the western periphery of the moisture reservoir to the east of the surface trough where MLCAPE values may be as high as 1000-2000 J/kg. While the central High Plains will likely remain displaced from the strongest mid/upper-level flow, 25-30 knot mid-level winds with modest low-level flow should provide sufficient deep-layer shear to support some degree of storm organization with an attendant large hail threat. Additionally, boundary-layer mixing on the edge of the deeper moisture will be adequately deep (mixed-layer LCLs near 2.5 km AGL) to support strong to severe gusts with the more organized cells and/or clusters. ...Great Basin/Four Corners... Increasing broad scale ascent over the Great Basin and Four Corners region should result in isolated to scattered thunderstorm development by late afternoon. While some degree of moisture return is anticipated from the Gulf of California across southern AZ, most regions will remain fairly warm and dry in the low-levels. Such thermodynamic conditions will be conducive for dry downbursts that may be capable of very localized strong to severe gusts. The predictability of where such gusts are most likely across the broader region remains too limited to warrant risk probabilities. ..Moore.. 09/14/2024 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Sat Sep 14 2024 Valid 141630Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Thunderstorms capable of producing isolated severe gusts and hail will be possible over parts of the north-central Plains this afternoon and evening. ...Northern/Central Plains... Modest ascent associated with a weak shortwave trough over eastern WY is encouraging towering cu and recent thunderstorm initiation across parts of western/central NE late this morning. This convective development is also occurring along/near a weak surface trough. Even though large-scale ascent is expected to remain fairly modest across much of the northern/central Plains today in the wake of a more prominent upper trough moving northeastward over central Canada, most guidance still shows potential for isolated to scattered thunderstorms developing this afternoon across parts of northwest NE into western/central SD along/near the surface trough. With modest/shallow low-level moisture in place, but steep mid-level lapse rates per 12Z LBF/UNR soundings, robust daytime heating will likely support around 1000-2000 J/kg of MLCAPE by mid afternoon. West-southwesterly flow at mid levels is forecast to be only modestly enhanced by the passing shortwave trough. Still, a veering and gradually strengthening wind profile with height through mid levels should support around 25-35 kt of deep-layer shear. Occasional hail may occur with any marginal supercells that can initially develop, although tendency for clustering and outflow interactions may lead to an isolated severe wind threat with time late this afternoon and early evening. The overall severe risk should quickly wane this evening with the loss of daytime heating. ...Southern High Plains... At least isolated high-based thunderstorms should develop this afternoon across parts of the TX Panhandle and vicinity along/east of a weak surface front/trough. With a deeply mixed boundary layer expected with daytime heating, occasional strong/gusty downdraft winds may occur with the more robust cores. However, weak deep-layer shear should keep the overall severe wind threat rather isolated. ...East Texas into Southern Louisiana/Mississippi... Isolated to widely scattered thunderstorms may develop along a weak front from parts of east TX into southern LA/MS later this afternoon. This activity would occur on the back side of a remnant mid-level circulation over the Mid-South. While modestly enhanced mid-level flow will be present, the potential for a more organized severe wind threat appears too low to include probabilities at this time. ..Gleason/Dean.. 09/14/2024 Read more