Severe Storms

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0651 AM CST Tue Mar 08 2022 Valid 081300Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TONIGHT OVER PARTS OF THE CENTRAL GULF COAST... ...SUMMARY... A marginal risk for severe thunderstorms exists tonight over parts of the central Gulf Coast. ...Synopsis... A series of mid/upper-level shortwave troughs, digging southward from western Canada, will reinforce the mean western CONUS trough, despite the ejection of an initially strong basal shortwave now over southern CO, NM and northwestern Chihuahua. The latter perturbation will deamplify somewhat, yet remain a well-defined shortwave trough, as it reaches parts of western KS, western OK, and northwest TX around 00Z. By 12Z, the trough should weaken further, with its 500-mb vorticity center reaching southern IL. A more-subtle, southern-stream perturbation -- initially apparent in moisture-channel imagery over the middle TX coast and vicinity -- should eject northeastward to the northern MS/northwestern AL region today, with some convective vorticity supplementation possible. This feature should accelerate northeastward near or offshore from the Mid-Atlantic Coast by the end of the period. At the surface, a cold front was drawn on the 11Z chart from offshore of New England southwestward across the SC coastal plain, becoming quasistationary southwestward across southwestern GA, across Choctawhatchee Bay and the mouth of the Mississippi River, and the northwestern Gulf. A weak frontal-wave low should develop over the southeastern LA/southeastern MS area this evening and ripple northeastward/inland along the front toward the GA/NC/TN border region by 12Z. Slight warm-frontal/northwestward motion should occur to its northeast, and cold-frontal advance to its southwest. A separate cold front, related to northern-stream upper-air processes, was analyzed across eastern ND, western SD, northeastern WY, and western MT. This boundary should move to parts of the upper Great Lakes, central Plains and central Rockies through the period, remaining well north of the first frontal zone. ..Central Gulf Coast... Isolated thunderstorms are possible throughout today and this evening along/ahead of the front -- with greater convective coverage in the zone of strongest large-scale lift (related to the ejecting TX Gulf Coast perturbation) behind the boundary. All this activity should remain non-severe, amidst little or no surface-based instability and moisture/buoyancy too weak for a substantial large-hail concern. However, late tonight after 06Z, a combination of strengthening warm-sector moisture and low-level lift near the low will support the potential for widely scattered thunderstorms moving northeastward over and just east of the frontal zone, offering isolated damaging gusts and a marginal tornado threat. The late-night activity also will be supported by large-scale lift in the form of strengthening low-level warm advection, collocated with a plume of moist advection and transport in a broadening LLJ. Surface dew points in the mid/upper 60s F will spread inland somewhat, with values near 70 F possible along the immediate coast and offshore. Though lapse rates in about the lowest 1/2 km and perhaps a few other layers beneath the 700 mb level near-surface lapse rates will remain weak, forecast soundings suggest MLCAPE near 1000 J/kg is possible over the Mississippi River mouth and from around MOB/PNS southward, and 500 J/kg across the rest of the outlook area. Though the LLJ core/speed max should remain north of the front, the nocturnal LLJ broadening across the boundary and into the warm sector will also result in enlarging low-level shear/hodographs, supporting effective SRH in the 150-250 J/kg range. Meanwhile, tightening of gradient flow aloft, related to the passage of both aforementioned shortwave troughs to the north, should help effective-shear magnitudes to strengthen to the 40-50-kt range. Minor eastward expansion of the outlook area is to give more room for potential movement of prefrontal convection over the western FL Panhandle by 12Z tomorrow. ..Edwards/Mosier.. 03/08/2022 Read more

No watches are valid as of Mon Mar 7 15:04:02 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Mar 7 15:04:02 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Mon Mar 07 2022 Valid 071300Z - 081200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TENNESSEE VALLEY/APPALACHIANS TO MID-ATLANTIC STATES... ...SUMMARY... Locally damaging wind gusts may accompany isolated thunderstorms from the Tennessee Valley and Appalachians to the coastal Mid-Atlantic today into this evening. ...Tennessee Valley/Appalachians to Mid-Atlantic coast... A lead shortwave trough/related jet streak, which are embedded within phasing westerlies, will quick spread northeastward from the Midwest to the Northeast and New England by tonight, while a secondary southern-stream trough evolves the southern Rockies. This will result in neutral height tendencies/limited overall forcing for ascent, as well as some mid-level warming, where moisture is more readily available across the Southeast States/southern Appalachians ahead of a cold front. Early this morning, a nearly continuous northeast/southwest-oriented line of thunderstorms extends from central Kentucky to Middle Tennessee and northern Mississippi. There has been a general updraft/downdraft intensity decrease in the predawn hours, but the organization of the line has nonetheless been maintained in the presence of weak buoyancy and very strong low-level/deep-layer shear. On the southern end, across the Tennessee Valley and southern Appalachians vicinity, low-level convergence may tend to weaken today, and while considerable cloud cover exists ahead of the cold front/convective line, a semi-moist air mass persists (60s F surface dewpoints) and a modest intensity boost could occur into this afternoon as the boundary layer warms. This may result in the potential maintenance of a semi-broken squall line and other bands of storms. Isolated damaging winds are the primary hazard. Farther north, across the central/northern Appalachians vicinity to the coastal Mid-Atlantic, a modest intensity/organizational uptick may occur near the cold front this afternoon as the cyclone continues to deepen from the Ohio Valley toward the Northeast/New England. Surface dewpoints will be limited to the 50s F, but a plume to relatively steep mid-level lapse rates may contribute to weak near-surface-rooted buoyancy, potentially with areas of a coupled hundred J/kg SBCAPE. This may be sufficient for an increasing potential for convectively augmented wind gusts, even in the relative absence of lightning, across the Appalachians this afternoon, and east of the mountains and toward the coastal Mid-Atlantic by early evening. Localized wind damage may occur. ..Guyer/Mosier.. 03/07/2022 Read more

No watches are valid as of Fri Mar 4 14:37:01 UTC 2022.

No Mesoscale Discussions are in effect as of Fri Mar 4 14:37:01 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0659 AM CST Fri Mar 04 2022 Valid 041300Z - 051200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms are possible today across portions of the southwestern U.S. into Colorado. Isolated thunderstorms are also expected late tonight from Nebraska into Iowa and southern Minnesota. ...Southwest States/Four Corners... A lead shortwave trough and related speed max over southern California this morning will eject northeastward and reach the Four Corners area this evening and the central High Plains late tonight. Along and north of this jet, cooling mid-level temperatures and steep lapse rates will contribute to weak buoyancy. This likely will be adequate for isolated semi-dry, high-based convection. While convection may struggle to produce appreciable precipitation, gusty winds could accompany some of this convection, especially during the afternoon across east/southeast Utah into western Colorado. While some stronger thunderstorm-related winds could materialize, the potential for severe-caliber thunderstorm-related gusts is currently expected to remain low. ...Central Plains/Upper Midwest... Late tonight, in tandem with weak height falls, an increasingly strong south-southwesterly low-level jet will develop across the central/southern Plains toward the upper Mississippi Valley. Elevated moisture transport will contribute to thermodynamic profiles that are increasingly conducive for thunderstorms, particularly across eastern Nebraska into Iowa and southern Minnesota (mainly 10 pm CST onward). While a few stronger thunderstorm updraft cores with hail may materialize late tonight, current expectations are for hail magnitudes to remain below severe levels given modest elevated buoyancy and an expected flow weakness in the lower part (650-800mb) of the cloud-bearing layer. ..Guyer/Dean.. 03/04/2022 Read more

No Mesoscale Discussions are in effect as of Thu Mar 3 14:43:01 UTC 2022.

No watches are valid as of Thu Mar 3 14:43:01 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0640 AM CST Thu Mar 03 2022 Valid 031300Z - 041200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms are expected across portions of southern California tonight. ...Southern California... Strong mid-level height falls (150m in 12hr) will overspread southern California and the Southwest Deserts tonight in advance of a southern-stream trough that will reach the SoCal coast early Friday morning. Increasing forcing for ascent and steepening low/mid-level lapse rates, along with a steady influx of low-level moisture, will be favorable for isolated thunderstorms tonight, initially offshore but subsequently into the coastal areas of SoCal. A couple hundred J/kg of SBCAPE could support some stronger/sustained low-topped thunderstorms late tonight/early Friday (09z-12z), potentially a few with weak/transient supercell characteristics owing to modest low-level hodograph curvature. Some gustier convectively related winds could materialize, but severe-caliber storms currently seem unlikely. ..Guyer/Leitman.. 03/03/2022 Read more

No Mesoscale Discussions are in effect as of Wed Mar 2 14:44:02 UTC 2022.

No watches are valid as of Wed Mar 2 14:44:02 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0654 AM CST Wed Mar 02 2022 Valid 021300Z - 031200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not forecast across the United States today or tonight. ...Synopsis/Discussion... The continued prevalence of dry/stable conditions across the Lower 48 will continue to result in an essentially nil thunderstorm potential today and tonight. The only conceivable potential for a lightning flash or two would be across northwest Washington in association with a shortwave trough approaching the British Columbia/Washington coasts. However, current expectations are for the shallow convection-related thermodynamic profiles to remain too marginal for a meaningful chance (10+ percent) and duration/coverage of thunderstorms. ..Guyer/Leitman.. 03/02/2022 Read more

No watches are valid as of Mon Feb 28 14:49:01 UTC 2022.

No Mesoscale Discussions are in effect as of Mon Feb 28 14:49:01 UTC 2022.

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0658 AM CST Mon Feb 28 2022 Valid 281300Z - 011200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms are expected across parts of northeast Florida and southeast Georgia today. ...Northern Florida/southeast Georgia... A southern-stream shortwave trough will continue east-southeastward over Florida and southern Georgia today, while a cold front will sag southward across the Florida Peninsula. Even to the north of the southward-advancing front with a drying boundary layer, cool mid-level temperatures and modest elevated buoyancy may be sufficient for isolated elevated thunderstorms across northeast Florida and possibly far southeast Georgia. Any such lightning-producing convection should shift offshore early this evening. ..Guyer/Leitman.. 02/28/2022 Read more

No watches are valid as of Fri Feb 25 14:40:02 UTC 2022.

MD 0189 CONCERNING HEAVY SNOW FOR NORTHEAST NY...VT...NH...MA...ME
Mesoscale Discussion 0189 NWS Storm Prediction Center Norman OK 0746 AM CST Fri Feb 25 2022 Areas affected...Northeast NY...VT...NH...MA...ME Concerning...Heavy snow Valid 251346Z - 251745Z SUMMARY...Heavy snowfall will continue to develop east-northeastward through the morning from eastern New York, northern Massachusetts, Vermont into New Hampshire and western/southern Maine. Snowfall rates in excess of 1 in/hr are likely for several hours with brief/locally higher rates possible. DISCUSSION...A low-amplitude shortwave trough over the Lower Great Lakes/southern Ontario at mid-morning will continue steadily east-northeastward, with increasing/eastward-transitioning forcing for ascent influencing eastern New York into New England early today. This is associated with DPVA and strong warm advection, with the latter directly influencing a transitional precipitation type across near-coastal/far southern New England. Aforementioned forcing for ascent coincident with a moderately deep and saturated dendritic growth layer will likely continue to support 1+ in/hr snowfall rates through the morning. With steep mid-level lapse rates noted in upstream observed soundings in proximity to the shortwave trough/dry slot, weak static stability/weak slantwise CAPE may also be an influence for a brief bout of locally higher snowfall rates, before snow/precip rates diminish from west-to-east into this afternoon. ..Guyer.. 02/25/2022 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CAR...GYX...BOX...BTV...ALY... LAT...LON 45047170 45497026 45366869 45046866 44256946 43197066 42517108 42787335 43757449 44467476 45087403 45047170 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0646 AM CST Fri Feb 25 2022 Valid 251300Z - 261200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are not expected across the continental United States today or tonight. ...Synopsis/Discussion... A deamplifying shortwave trough will continue east-northeastward over the Northeast States and New England, with a cold front advancing east-southeastward across the coastal Southeast States. A few lightning flashes have been noted in the predawn hours near/behind this front. However, weakening low-level convergence and increasingly marginal thermodynamic profiles suggest that the potential for thunderstorms into the Carolinas/Mid-Atlantic region will likely remain below 10 percent. Dry/stable conditions will otherwise preclude thunderstorms across the remainder of the CONUS. ..Guyer.. 02/25/2022 Read more

No watches are valid as of Thu Feb 24 14:48:01 UTC 2022.