Severe Storms

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1118 AM CDT Wed Aug 10 2022 Valid 101630Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE MID-ATLANTIC REGION AND INLAND PACIFIC NORTHWEST.... ...SUMMARY... Isolated severe thunderstorms are possible in parts of the Mid-Atlantic region and inland Pacific Northwest. ...Mid Atlantic... Warm and humid surface conditions are present today over the Mid Atlantic region, with strong daytime heating resulting in afternoon MLCAPE of 2500 J/kg. A consensus of 12z model guidance suggests that scattered thunderstorms will form by early-afternoon over the mountains of eastern WV and western VA. This activity will spread slowly eastward into the Chesapeake Bay region. Forecast soundings and recent ACARS data from the DC/Baltimore area show very weak winds aloft and poor mid-level lapse rates. Given the lack of large scale forcing mechanisms, convection that forms in this area should be weakly organized. Nevertheless, isolated tree damage may briefly occur with the strongest cells. ...WA/OR... An upper low is tracking northward off the OR/WA coast today, with relatively strong southerly deep-layer flow across the interior Pacific Northwest. Mostly clear skies and dewpoints in the 50s will result in a corridor of sufficient CAPE to pose a conditional threat of strong/severe storms this afternoon and evening across the MRGL risk area. Model guidance suggests that the coverage of storms will be quite limited. Nevertheless, any storm that can form/persist will pose a risk of gusty winds and hail. ..Hart/Weinman.. 08/10/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1057 AM CDT Wed Aug 10 2022 Valid 101700Z - 111200Z The forecast generally remains on track. The main adjustments for this update were to trim both the Elevated and Dry Thunderstorm risk areas across the Pacific Northwest to account for recent wetting rainfall and to minimize overlap with areas expected to receive heavy precipitation this afternoon (based on latest ensemble QPF probabilities). Despite the unseasonably high low-level moisture noted in morning surface obs across eastern WA/OR and western ID, forecast soundings continue to show fast storm motions and sufficient diurnal warming to support deeply mixed boundary layers favorable for a few dry lightning strikes over receptive fuels. A few nocturnal showers/thunderstorms are possible over northern MT, but the potential for dry lightning appears too limited for additional highlights. See the previous discussion for additional details. ..Moore.. 08/10/2022 .PREV DISCUSSION... /ISSUED 0155 AM CDT Wed Aug 10 2022/ ...Synopsis... On the western periphery of strong mid-level high pressure dominating the central CONUS, a compact upper low is expected to continue northward along the West Coast. A second trough is forecast move eastward along the northern rim of the ridge across portions of the northern Rockies and High Plains. Enhanced by southerly gradient winds between the upper low and ridge, mid-level moisture will continue to spill into the Pacific Northwest and northern Rockies. Stronger flow aloft and lift from the two troughs will support scattered thunderstorms and the potential for elevated fire weather concerns. ...Northern CA/southern OR and western MT... As heights lower ahead of the upper low and shortwave trough, enhanced mid-level flow is forecast to develop along the northwestern periphery of the ridge across CA/OR and portions of MT. This enhanced flow will overspread a dry and warm airmass in the lee of the northern Sierra and across the northern Rockies/High Plains. Afternoon RH values below 25% and surface winds peaking near 20 mph should support several hours of elevated to near-critical fire weather conditions within receptive fuels. A few high-based thunderstorms may also support strong and erratic gusts this afternoon/evening. ...Dry Thunderstorms... As the upper low continues to move slowly north along the West Coast, dynamic lift will overspread abundant mid-level moisture in place across the Northwest and northern Rockies. Area soundings show PWAT values of 1-1.5 inches supporting elevated CAPE of 500-1000 J/kg. Beneath the unstable layers, modest low-level moisture and warm surface temperatures should result in drier sub-cloud layers with inverted-v structures. Higher evaporation potential should favor a drier storm mode with the threat of occasional cloud to ground strikes to receptive fuels. IsoDryT probabilities will be maintained across portions of the interior Northwest and northern Rockies. Farther west across the Olympic Peninsula and western Washington, dry thunder potential is less certain given much cooler surface conditions near an inland marine layer. While elevated buoyancy is expected to support a risk for storms beneath the cold core of the upper low, storm mode is forecast to be significantly wetter. While isolated cloud to ground strikes will be possible within receptive fuels, dry thunderstorms appear unlikely, and IsoDryT probabilities will be held farther east. For additional information of the severe-weather risk, please see the most recent Convective Outlook. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Tue Aug 9 17:53:01 UTC 2022.

MD 1669 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF CENTRAL OR...FAR NORTHEAST CA...AND FAR NORTHWEST NV
Mesoscale Discussion 1669 NWS Storm Prediction Center Norman OK 1251 PM CDT Tue Aug 09 2022 Areas affected...Parts of central OR...far northeast CA...and far northwest NV Concerning...Severe potential...Watch unlikely Valid 091751Z - 092115Z Probability of Watch Issuance...20 percent SUMMARY...The risk of isolated large hail and locally severe gusts will gradually increase through the afternoon. A watch is not currently expected. DISCUSSION...Ahead of a mid/upper-level low off the coast of northern CA, a belt of deep/enhanced meridional flow (sampled by regional 12z soundings) will continue overspreading northern CA into south-central OR this afternoon. Recent water vapor imagery showed a subtle embedded midlevel impulse moving northward across the area, which combined with sufficient midlevel moisture/buoyancy has resulted in an uptick in shallow convection along the higher terrain in OR. Currently, lingering low-level inhibition and minimal buoyancy are limiting updraft intensity, though isolated small hail and locally strong gusts are still possible with this activity. Behind this initial uptick in convection, diurnal heating/mixing beneath a plume of modest midlevel lapse rates should contribute to moderate surface-based instability by this afternoon, though ongoing activity casts uncertainty on overall boundary-layer recovery (especially over parts of OR along the Cascades). Nevertheless, if an additional uptick in diurnally enhanced convection can intercept pockets of surface-based inflow, 40-50 kt effective shear -- characterized by a long/generally straight hodograph -- would support splitting supercell structures and locally organized clusters. Isolated large hail and locally severe gusts may accompany any persistent rotating updrafts or organized clusters, though the threat appears too localized for a watch. ..Weinman/Hart.. 08/09/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOI...LKN...PDT...REV...MFR...PQR... LAT...LON 42301812 41721828 41131887 40861978 41062044 41962083 42782154 43462208 43872223 44552227 44912216 45112174 45182055 44911942 44431864 43801827 42761806 42301812 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1223 PM CDT Tue Aug 09 2022 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WEDNESDAY AFTERNOON AND EVENING ACROSS NORTHERN AND EASTERN VIRGINIA...CENTRAL AND EASTERN MARYLAND...MUCH OF DELAWARE...CENTRAL AND EASTERN WASHINGTON AND NORTHEASTERN OREGON... ...SUMMARY... A cluster of strong thunderstorms, posing a risk for locally gusty and damaging winds, may develop across parts of the Mid Atlantic Wednesday afternoon and evening. Isolated strong thunderstorms may also impact parts of the northern intermountain region, accompanied by at least some risk for severe weather. ...Synopsis... Little change to the amplified regime across the mid- and subtropical latitudes of the eastern Pacific into the interior of the U.S. is forecast through this period. Mid-level ridging, with a broad and prominent embedded high, will remain centered across the Rockies and Great Plains, downstream of large-scale troughing near and offshore of the Pacific coast. Near and just east of the mid-level trough axis, a significant embedded low appears likely to continue migrating slowly northward just offshore of the Oregon and Washington coasts. To the east of the ridging, large-scale mid-level troughing, with a couple of vigorous embedded perturbations, is forecast to gradually dig across and southeast of the southern Hudson/James Bay and upper Great Lakes vicinities. Models suggest that this will be preceded by weak mid-level troughing digging southeast of the lower Great Lakes through the Mid Atlantic vicinity by late Wednesday night. In association with this regime, an initial cold front may gradually stall and weaken across the Mid Atlantic coast and Ohio Valley into Ozark Plateau and central Great Plains vicinity, as a reinforcing cold front advances across much of the Great Lakes region by daybreak Thursday. Seasonably high moisture content will largely remain confined to the south of the lead front, to the east of the Rockies. Across the west, a plume of monsoonal moisture emanating from Southwest will be maintained, but perhaps slowly shift eastward across the northern intermountain region/Great Basin, ahead of subsidence/drying in the wake of the offshore low. ...Mid Atlantic... As the surface front advances offshore of the northern Mid Atlantic coast, models suggest that insolation across and to the lee of the Blue Ridge may contribute to a zone of stronger differential surface heating across the Potomac/Chesapeake vicinity Wednesday afternoon. Despite rather weak deep-layer mean flow and shear, it is possible that this boundary could provide a focus for consolidating thunderstorm activity with some potential to organize by late afternoon. Aided by inflow of seasonably moist boundary-layer air characterized by CAPE on the order of 1000-2000+ J/kg, this convection may generate outflow supportive of strong to severe surface gusts, before weakening Wednesday evening. ...Washington/Oregon... Uncertainty lingers concerning the extent and degree of appreciable boundary-layer destabilization across the northern intermountain region on Wednesday. However, aided by large-scale forcing for ascent to the northeast through east of the northward migrating offshore low, at least widely scattered thunderstorm development appears possible Wednesday afternoon and evening, particularly off the mountains of northeastern Oregon and near the higher terrain north of the Columbia Plateau. Beneath 40-70+ kt southerly flow in the 500-300 mb layer, forecast soundings indicate that hodographs will become conditionally supportive of supercells posing at least a risk for severe wind and hail. ..Kerr.. 08/09/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1148 AM CDT Tue Aug 09 2022 Valid 091630Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID-ATLANTIC INTO SOUTHERN NEW ENGLAND...AND IN PARTS OF THE INTERIOR PACIFIC NORTHWEST.... CORRECTED FOR HAIL GRAPHIC ERROR ...SUMMARY... Thunderstorms associated with damaging wind gusts will be possible today from the Mid-Atlantic into southern New England, and in parts of the Interior Pacific Northwest. ...Northeast States... A surface cold front is analyzed this morning from central New England into central PA. This front will sag southeastward today into a hot/moist low-level environment with temperatures in the 90s and dewpoints in the 70s. Forecast soundings show weak mid-level lapse rates and warm temperatures aloft, which should be negative factors for convective coverage and intensity. Nevertheless, at least isolated thunderstorms are expected to form on the front later today, with the strongest cells posing a risk of locally damaging wind gusts. ...Central OR... A large upper low is present off the coast of northern CA today, with rather strong southerly deep-layer flow extending northward across much of western and central OR. 12z model guidance continues to show multiple waves of convection affecting the MRGL risk area through this evening, where sufficient CAPE and deep-layer shear will be present for a few organized storms. The main threat appears to be locally damaging wind gusts in pockets of stronger heating, but an isolated supercell or two cannot be ruled out, with an associated risk of gusty winds or hail. ..Hart/Weinman.. 08/09/2022 Read more

MD 1668 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR EASTERN MD...SOUTHERN PA...DE...NJ...SOUTHERN NY..CT...MA...RI
Mesoscale Discussion 1668 NWS Storm Prediction Center Norman OK 1143 AM CDT Tue Aug 09 2022 Areas affected...Eastern MD...Southern PA...DE...NJ...Southern NY..CT...MA...RI Concerning...Severe potential...Watch unlikely Valid 091643Z - 091845Z Probability of Watch Issuance...20 percent SUMMARY...Isolated damaging wind gusts are possible this afternoon from the northern Mid-Atlantic into southern New England. DISCUSSION...Recent surface analysis places a low over southern ME, with a cold front extending southwestward from this low across the central Hudson Valley into central PA. A weak trough also precedes this front. extending southward through central MA and central CT into northern NJ and far eastern PA. Current surface observations also reveal dewpoints in the 70s areawide, with numerous locations reporting dewpoints in mid 70s. Cumulus continues to deepen in the vicinity of the surface trough as the air mass heats and destabilizes. This trend is expected to persist throughout the afternoon, resulting in the development of scattered thunderstorms. The stronger mid-level flow will be over ME, displaced north of the stronger buoyancy, which is expected across the Delmarva, eastern PA, and NJ. Additionally, the overall instability will be limited by weak mid-level lapse rates and warm thermodynamic profiles. Even so, steep low-level lapse rates coupled with a very moist air mass could still support locally damaging wind gusts with any stronger storms. ..Mosier/Hart.. 08/09/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOX...OKX...ALY...PHI...BGM...CTP...LWX... LAT...LON 38717592 39607707 40517661 42477238 41977151 40807305 39687417 38757492 38717592 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1008 AM CDT Tue Aug 09 2022 Valid 091700Z - 101200Z The previous forecast remains on track with only minor adjustments required. 12 UTC regional soundings and latest satellite estimates show PWAT values have increase to around 1 inch across much of the Pacific Northwest. An embedded impulse is noted in morning water-vapor imagery pivoting north/northeastward along the West Coast. This feature will support scattered thunderstorm development by early afternoon. The highest thunderstorm coverage remains most likely across central to southeast OR, but more isolated dry thunderstorms are possible in this periphery of this axis. Strong thunderstorm outflows remain likely and may reach severe (58+ mph) wind speeds. See the previous discussion for additional details, and see the recent Day 1 Convective Outlook for more information on the severe weather potential. ..Moore.. 08/09/2022 .PREV DISCUSSION... /ISSUED 0145 AM CDT Tue Aug 09 2022/ ...Synopsis... An upper ridge will persist across the western CONUS as a mid-level closed low impinges on the West Coast today. Strong 500 mb flow in advance of the mid-level closed low will overspread the Cascades during the afternoon, providing adequate upper support for initiating several thunderstorms when considering the presence of low to mid-level monsoonal moisture. While storms will be fast moving, the concentration of storms (several of which may be training) along with precipitable water values approaching 1.25 inches suggest that wetting rains should accompany at least most of the storms. Nonetheless, the abundance of storms will also increase the odds of peripheral lightning strikes away from cores. Downward momentum of the stronger mid-level flow in thunderstorms may also support strong, erratic gusts. As such, isolated dry thunderstorm highlights have been maintained for the combined threats of peripheral strikes within spotty dry fuel beds and gusty thunderstorm winds, which can exacerbate ongoing wildfires. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Mon Aug 8 17:58:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1219 PM CDT Mon Aug 08 2022 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY AFTERNOON ACROSS PARTS OF CENTRAL OREGON AND PARTS OF THE NORTHERN MID ATLANTIC INTO SOUTHERN NEW ENGLAND... ...SUMMARY... Isolated to widely scattered strong thunderstorms may impact parts of central Oregon, as well as portions of the Mid Atlantic and southern New England, Tuesday afternoon, and pose at least some risk for severe weather. ...Synopsis... In the southern mid- and subtropical latitudes, models indicate that weak lower/mid tropospheric ridging will prevail across the western Atlantic into much of the Southeast through this period. At the same time, to the west, a mid-level high is forecast to become increasingly prominent near/east of the Rockies into much of the Great Plains, downstream of amplified mid-level troughing near/offshore of the U.S. Pacific coast. While there will likely be little, if any, eastward progression of this larger-scale troughing, a fairly deep embedded mid-level low may migrate slowly north-northeastward offshore of the northern California/southern Oregon coast. Flow in the higher latitudes likely will remain more zonal and progressive. This is forecast to include one significant mid-level trough, with a couple of vigorous embedded smaller-scale perturbations, shifting east of the Canadian Prairies through the northern Ontario/Hudson Bay/western Quebec vicinity by 12Z Wednesday. A much more modest preceding perturbation is forecast to accelerate across and east of the Canadian Maritimes and New England into the northern Atlantic. This will be accompanied by the southward advancement of one surface cold front across the St. Lawrence Valley, and to the lee of the lower Great Lakes, offshore of New England into northern Mid Atlantic coast by late Tuesday night. The western flank of this front likely will stall across the lower Ohio into middle Mississippi Valleys, while a reinforcing front advances into the Upper Midwest and northern Great Plains. Moisture content will remain seasonably high along and to the south of the lead front, to the east of the Rockies, while monsoonal moisture will gradually advect around the southwestern periphery of the strengthening high, from the Southwest into the northern intermountain region, to the east of the developing low offshore of the Pacific coast. ...Northeast... Large-scale forcing for ascent along and ahead of the southward advancing front appears likely to remain generally modest to weak. However, strong heating of a moist boundary layer (temps rising into the 90s with surface dew points in the mid 60s to around 70F) may contribute to moderate CAPE (on the order of 1000-2000 J/kg) along the front and pre-frontal surface trough, inland of the northern Mid Atlantic into southern New England coast by Tuesday afternoon. It appears that this will be sufficient to support widely scattered to scattered thunderstorms. Although deep-layer shear will be weak, model forecast soundings indicate southwesterly to westerly flow around 20 kt in the 850-700 mb layer. This may be enough, coupled with the fairly steep low-level lapse rates and potential heavy precipitation loading, to support the risk for a few potentially damaging wind gusts before storms weaken by Tuesday evening. ...Central Oregon (near/east of the Cascades)... Downstream (to the northeast of the approaching mid-level low), forcing for ascent is generally forecast to contribute to considerable thunderstorm development Tuesday afternoon into Tuesday evening. Forecast soundings indicate that CAPE may remain limited to 500-1000 J/kg or less, but beneath 30-70 kt southerly flow in the 500-300 mb layer, strong deep-layer shear will be at least conditionally supportive of isolated supercells posing a risk to produce severe hail and locally strong surface gusts. ..Kerr.. 08/08/2022 Read more

MD 1666 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR CENTRAL/EASTERN NY...NORTHWEST CT...WESTERN MA...AND SOUTHERN VT
Mesoscale Discussion 1666 NWS Storm Prediction Center Norman OK 1158 AM CDT Mon Aug 08 2022 Areas affected...Central/eastern NY...northwest CT...western MA...and southern VT Concerning...Severe potential...Watch unlikely Valid 081658Z - 081830Z Probability of Watch Issuance...20 percent SUMMARY...Isolated strong/damaging gusts with downbursts will be possible this afternoon, but the threat appears to be too marginal for a watch. DISCUSSION...To the east of a midlevel perturbation and thicker clouds over western NY, surface temperatures are warming into the upper 80s/near 90 F, with boundary-layer dewpoints holding in the lower 70s from central NY eastward. Despite poor midlevel lapse rates, MLCAPE has increased to 1000-1500 J/kg, with minimal convective inhibition. Weak ascent in advance of the subtle midlevel trough and continued surface heating/mixing will support widely scattered thunderstorm development through the afternoon. Vertical shear is weak in the warm sector, but 20-30 kt westerly flow in the 700-500 mb layer will support cells/multicell clusters that will spread eastward. Precipitation loading in the stronger updrafts, in combination with steepening low-level lapse rates and DCAPE near 1000 J/kg, will support the threat for a few strong downbursts capable of producing isolated wind damage. ..Thompson/Hart.. 08/08/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX...BOX...BTV...ALY...BGM...BUF... LAT...LON 42047527 42267571 42727588 43087590 43487566 43807536 43967460 44067354 44087299 44047285 43497242 42877250 42257271 41827315 41607383 41957463 42047527 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1052 AM CDT Mon Aug 08 2022 Valid 081630Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF SOUTHERN LOWER MICHIGAN AND NORTHERN INDIANA INTO WESTERN NEW ENGLAND.... ...SUMMARY... Isolated damaging thunderstorm gusts may occur today from parts of southern Lower Michigan and northern Indiana into western New England. ...MI/IN/OH... Morning water vapor loop shows a shortwave trough moving across Lake Superior into Ontario. The associated trailing cold front extends across northern Lower MI into northern IL. Considerable cloud cover is present ahead of the front, but a combination of dewpoints in the 70s and broken sunshine will yield afternoon MLCAPE values of 1500-2000 J/kg. Most 12z model solutions suggest that scattered thunderstorms will develop later today as the cold front sags into southern Lower MI and northern IN/OH. Mid level lapse rates are weak, but steep low-level lapse rates and sufficient steering flow will pose some risk of locally gusty/damaging winds in the strongest cells. ...NY/western New England... Visible satellite imagery showed mostly clear skies this morning from central NY into much of central/southern New England. This area has already begun to show a considerable cu field, and is likely to develop into isolated thunderstorms by mid-afternoon. Temperatures in the mid/upper 80s will lead to steep low-level lapse rates and MLCAPE values around 1500 J/kg. Flow aloft is rather weak, but the strongest cells in this area may produce gusty/damaging winds this afternoon and early evening. ..Hart/Thompson.. 08/08/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1015 AM CDT Mon Aug 08 2022 Valid 081700Z - 091200Z ...CRITICAL FIRE WEATHER AREA FOR CENTRAL TO SOUTH-CENTRAL OREGON... The previous forecast remains on track with only minor adjustments needed. Isolated showers/thunderstorms are already ongoing this morning, but will become more numerous by mid/late afternoon. An increase in mid-level moisture was sampled in regional 12 UTC soundings with dry boundary-layer conditions noted along/east of the Cascades. These observed trends and latest ensemble guidance both support the ongoing forecast. See the previous discussion below for additional details. ..Moore.. 08/08/2022 .PREV DISCUSSION... /ISSUED 0137 AM CDT Mon Aug 08 2022/ ...Synopsis... Upper ridging will dominate the Interior West as an upper low meanders off of the West Coast today. Monsoonal moisture will pivot northwestward around the periphery of the upper ridge across the Desert Southwest into the Pacific Northwest, where scattered thunderstorms are expected to develop by afternoon. Across far southern Washington into central Oregon and extreme northern California/northwestern Nevada, many of the thunderstorms are expected to be high-based. Forecast soundings in this area by afternoon peak heating suggest that a very dry boundary layer will extend up to 500 mb amid precipitable water values around 0.75 inches. As such, a mix of wet and dry thunderstorms is expected to overspread modestly to highly receptive fuels, warranting isolated dry thunderstorm highlights. Scattered dry thunderstorm highlights were also maintained across central/southern Oregon, where the latest high-resolution guidance consensus continues to depict the greatest concentration of thunderstorms. Lastly, high-resolution ensemble guidance shows relatively high potential for erratic and gusty winds (perhaps 30-45 kts) accompanying the stronger thunderstorms across the southern Cascades, which may exacerbate any new or pre-existing fire starts. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sun Aug 7 18:01:01 UTC 2022.

No Mesoscale Discussions are in effect as of Sun Aug 7 18:01:01 UTC 2022.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Sun Aug 07 2022 Valid 081200Z - 091200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The severe thunderstorm threat is expected to be relatively low on Monday. ...Lower MI into parts of the Midwest... A midlevel shortwave trough will move quickly from the upper Great Lakes toward parts of Ontario and Quebec on Monday, as a trailing cold front moves through parts of the Midwest and eventually the lower Great Lakes. Depending on the extent of diurnal heating that can occur in the wake of morning convection, moderate buoyancy may develop by afternoon within a very moist environment. Deep-layer will be modest at best across lower MI, and even weaker farther south, but a belt of somewhat enhanced flow (25-35 kt) in the 850-700 mb layer may support storm clusters capable of isolated wind damage, if sufficient heating and steepening of low-level lapse rates can occur. Wind probabilities may eventually be needed for portions of this region, depending on how much recovery/heating can occur in the wake of morning cloudiness and convection. ...Arizona... A few strong storms will again be possible across parts of Arizona, mainly across southeast AZ and also potentially along the Mogollon Rim, as moderate buoyancy develops within a seasonably moist environment. Depending on the extent of recovery that can occur in the wake of convection on D1/Sunday, a threat of isolated severe gusts and perhaps some hail may evolve, though confidence is too low to add probabilities at this time. ..Dean.. 08/07/2022 Read more

SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook CORR 1 NWS Storm Prediction Center Norman OK 1119 AM CDT Sun Aug 07 2022 Valid 071630Z - 081200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF ARIZONA...THE CENTRAL HIGH PLAINS...IOWA...AND NORTHERN MAINE.... CORRECTED FOR GRAPHICAL CREATION ERRORS ...SUMMARY... Isolated severe thunderstorm gusts are possible across parts of Arizona, the Upper Midwest and central High Plains, and northern Maine this afternoon and evening. ...CO/KS... Morning surface analysis shows a persistent boundary extending across northwest KS into southeast CO. Dewpoints are in the 60s along and north of the boundary across much of eastern CO, and it appears that considerable daytime heating will occur over parts of the area. This will result in afternoon MLCAPE values of around 1000 J/kg over much of eastern CO, with values up to 2500 J/kg over western KS. Most 12z models agree that convection will form over the foothills of central CO by mid afternoon and spread eastward through early evening. Winds aloft are sufficiently strong to help propagate the convection off the higher terrain, as well as organize a few of the updrafts. Locally damaging wind gusts will be the main threat, but a few storms in/near the foothills may produce hail. Farther east in the plains, strong CAPE values and convergence along the boundary may be sufficient for a landspout or two, along with gusty/damaging winds. ...IA... Widespread overnight convection has left an outflow boundary extending across central IA. It is unclear how much daytime heating will occur in this area due to remnant clouds. However, the potential will exist for isolated gusty/damaging wind gusts in the stronger cells this afternoon and evening if sufficient low-level lapse rates can develop. ...Northern ME... A surface cold front is sagging southward across Quebec towards northern ME. A moist and marginally unstable air mass will be present this afternoon as storms initiate along the front. Forecast soundings suggest sufficient deep-layer shear for an isolated rotating storm or two, capable of damaging wind gusts or hail. ...AZ... Strong heating is occurring today over most areas of central/southern AZ. Clusters of thunderstorms are expected to develop by mid-afternoon over the mountains of central/eastern AZ and propagate southwestward. The mesoscale details of convective coverage are unclear, but there will be potential for damaging wind gusts if storms can persist as they track into south-central AZ this evening. ..Hart/Weinman.. 08/07/2022 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1057 AM CDT Sun Aug 07 2022 Valid 071700Z - 081200Z The forecast remains on track with only minor adjustments required based on latest hi-res convective guidance. See the previous discussion below for details. ..Moore.. 08/07/2022 .PREV DISCUSSION... /ISSUED 1229 AM CDT Sun Aug 07 2022/ ...Synopsis... A mid-level short-wave trough positioned over the northern Plains will shift east into the Great Lakes region throughout the day. Meanwhile, an upper-level ridge will build across the northern Rockies, and a closed upper-level low will approach the northern California/southern Oregon coast. At the surface, a cold front will continue a slow progression across the northern/central High Plains. ...Isolated Dry Thunderstorms: Central/Southern Oregon/far Northern California/far Northwest Nevada... The area delineating potential for isolated dry thunderstorms has been expanded slightly toward the northwest, based on 00z CAM guidance. Coverage of this activity should remain isolated, supported by forecast PWAT values still remaining near or below 0.75-0.8 inches, and fuels across the region remain highly receptive to large-fire spread. ...Wind/RH: Northern Oregon/Southern Washington... Localized elevated conditions may develop during the afternoon, as a hot/dry airmass will be present over the region. Locally enhanced offshore flow will likely occur in terrain-favored regions of the Cascades. Given the isolated nature of the threat, however, no highlights have been introduced at this time. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

No watches are valid as of Sat Aug 6 17:59:01 UTC 2022.

No Mesoscale Discussions are in effect as of Sat Aug 6 17:59:01 UTC 2022.