Storm Prediction Center
No watches are valid as of Mon Oct 25 17:40:02 UTC 2021.
No Mesoscale Discussions are in effect as of Mon Oct 25 17:40:02 UTC 2021.
SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 AM CDT Mon Oct 25 2021 Valid 251300Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL/SOUTHERN APPALACHIANS AND MID-ATLANTIC STATES... ...SUMMARY... Thunderstorms capable of damaging winds and possibly a tornado risk are expected from the southern and central Appalachians into the Carolinas and Mid-Atlantic region, mainly this afternoon and evening. ...Upper Ohio Valley to the Mid-Atlantic States/Carolinas... The remnants of last evening's severe storms across the Ozarks/Middle Mississippi Valley grew upscale and persist early this morning in a diminished intensity from Ohio south-southwestward into eastern portions of Kentucky and middle/eastern Tennessee, parallel to but ahead of an eastward-moving cold front. The parent shortwave trough will continue eastward over the Midwest/Ohio Valley toward the central/northern Appalachians through tonight, with height falls and the exit region of a strong mid/upper jet overspreading the southern Appalachians and Carolinas/Virginia. The aforementioned bands of convection and related cloud cover will tend to hinder pre-frontal destabilization across the Upper Ohio Valley and windward side of the Appalachians, but a few strong/severe low-topped storms could occur pending weak but sufficient destabilization this afternoon in those areas. A more certain/probable severe-weather risk is expected this afternoon east of the Appalachians spine, perhaps initially near/just east of the Blue Ridge across Virginia and nearby Maryland/North Carolina. This is where cloud breaks ahead of the upstream cold front and lingering overnight convection should allow for modest destabilization, with upwards of 1000 J/kg MLCAPE possible from the North Carolina/Virginia Blue Ridge and Piedmont vicinities toward the Delmarva by late afternoon. Strong deep-layer shear will support some well-organized storms including linear bands aside from the possibility of some initial/embedded supercells, particularly across the Piedmont of Virginia and northern North Carolina. Although low-level shear will not be overly strong and details of convective mode are a bit uncertain, the potential for a tornado or two could somewhat increase late this afternoon/early evening. This would particularly be across southern Virginia/northern North Carolina pending weak lee-side low/trough development and a related increase in low-level shear/SRH. Damaging winds will otherwise be the most probable hazard across the region this afternoon and evening, with a few instances of marginally severe hail also a possibility. ...Florida... A couple of stronger storms may persist toward and across the central/southern Florida Peninsula and Keys vicinity today. However, the potential for severe-caliber storms should be limited by relatively poor mid-level lapse rates, weak vertical shear, and weakening low-level convergence. ..Guyer/Kerr.. 10/25/2021Read more
SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1127 AM CDT Mon Oct 25 2021 Valid 251630Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON/EVENING FOR CENTRAL NC INTO VA... ...SUMMARY... Occasional damaging gusts and a tornado or two will be possible this afternoon/evening from central North Carolina into Virginia. ...Eastern KY/OH to NC/VA this afternoon/evening... A midlevel shortwave trough over IN/KY/TN this morning will progress eastward to the Appalachians this evening and VA/NC overnight. An associated surface cyclone will move eastward from northeast IN across northern OH today while slowly weakening, and a trailing cold front will likewise move eastward across TN/KY/WV/OH through this evening. A band of convection will be possible along the cold front this afternoon in conjunction with a narrow zone of cloud breaks/surface heating and modest low-level moisture (surface dewpoints of 56-60 F) across OH/KY. Buoyancy will remain weak (MLCAPE 500 J/kg) and wind profiles will be only modestly favorable for organized severe storms (effective bulk shear near 30 kt) suggest that any severe threat with to storms along the cold front should remain marginal. Farther east, low-level moisture is increasing from eastern NC into VA, on the west side of a separate shortwave trough ejecting northeastward near the southeast Atlantic coast. The moisture should be able to spread far enough west and north to support thunderstorm development later this afternoon near the Blue Ridge, as the primary cloud/ascent band (now across eastern KY into WV) reaches the west edge of the richer low-level moisture. Wind profiles will be sufficient for supercells with effective bulk shear of 40-50 kt, given MLCAPE up to 1000 J/kg. Occasional damaging gusts will be the main concern, though a tornado or two may also occur near the NC/VA border where effective SRH of 100-150 m2/s2 is expected by late afternoon. Otherwise, convection is expected to grow upscale into clusters/line segments, with an attendant threat for damaging winds through late evening. ..Thompson/Wendt.. 10/25/2021Read more
SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1234 PM CDT Mon Oct 25 2021 Valid 261200Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF THE CENTRAL AND SOUTHERN PLAINS... ...SUMMARY... Scattered severe thunderstorms associated with large hail, wind damage and isolated tornadoes are expected across parts of the southern and central Plains from late Tuesday afternoon through the evening into the overnight. ...Central through southern Plains... Upper trough currently moving into the western U.S. will amplify as it continues east into the central and southern Plains Tuesday. A lee cyclone will develop in association with this feature with the strengthening southerly low-level jet drawing partially modified Gulf air northward beneath steepening mid-level lapse rates resulting in a corridor of moderate instability with up to 1500 J/kg MLCAPE. Some low clouds may accompany the moisture return, the extent of which remains somewhat uncertain. Storms will likely develop by late afternoon as the cold front advances east and merges with the dryline. A few discrete storms might initiate along the dryline prior to the frontal merger, but extent of this development is dependent on the degree of boundary layer heating. More numerous storms are expected toward evening as the front begins to merge with the dryline from western KS southward into eastern parts of western TX. Wind profiles with 40-50 kt effective bulk shear will support some supercells with all hazards possible. Storms will eventually evolve into an MCS with damaging wind becoming the main threat as activity continues east overnight. Some potential exists for a greater tornado threat than what is currently indicated, but uncertainty regarding extent of boundary layer destabilization and mode evolution lowers confidence in increasing probabilities for this update. ..Dial.. 10/25/2021Read more