Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
370 ACUS02 KWNS 270521 SWODY2 SPC AC 270520 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1220 AM CDT Mon Jul 27 2026 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN MID-ATLANTIC INTO THE CAROLINAS AND CENTRAL AND SOUTHERN APPALACHIANS... ...SUMMARY... Severe thunderstorms capable of damaging winds and isolated hail are possible from the southern Mid-Atlantic into the Carolinas and central and southern Appalachians Tuesday into Tuesday evening. Isolated severe wind gusts and large hail may occur in the central High Plains. ...Synopsis... Considerable trough amplification is forecast over the eastern CONUS this period, aided by the propagation of the mid/upper-level jet streaks from the Great Lakes and OH Valley through VA and NC. A series of vorticity maxima is forecast on the cyclonic side of the jet streaks, which will enhance forcing for ascent over the central Appalachians into the Mid-Atlantic. At the surface, the primary low pressure is expected to deepen over the Delmarva with a secondary cyclone over western NY. A lee trough will extend from the Delmarva low south-southwest along the Piedmont, ahead of a cold front moving through the TN Valley and central and southern Appalachians. ...Mid-Atlantic into the Southern Appalachians... Showers and thunderstorms (some potentially severe with damaging winds) are expected to be ongoing Tuesday morning from the lower Great Lakes into the central Appalachians. The longevity and areal extent of the early-day storms will be a determinant in where more robust air mass destabilization will take place during the afternoon. The 00Z HREF calibrated thunder probabilities suggest the most likely areas for persistent morning storms will be from NY and PA into the Delmarva and WV. To the south of those locations, stronger daytime heating appears more probable, which, combined with boundary-layer dewpoints in the upper 60s to mid 70s, will yield moderate to potentially strong afternoon instability with MLCAPE of 1500-2500+ J/kg. Thunderstorms are expected to increase in coverage and intensity during the afternoon along and ahead of the cold front and lee trough as background forcing for ascent strengthens in the left exit region of the approaching upper-level jet streak. The presence of the mid/upper-level wind maxima will yield long hodographs with sufficient vertical shear for supercells and bowing structures. The strengthening shear combined with cooling mid-level temperatures will be supportive of large-hail production with any supercells that form. Otherwise, damaging winds will be the primary hazard, especially with any storm clusters or bowing line segments. Some tornado threat could also materialize Tuesday afternoon into evening near and south of the Delmarva surface low where slightly stronger low-level shear is forecast. ...Central High Plains... Strong heating of a moist, upslope-flow air mass is expected to yield a moderately unstable environment by afternoon with MLCAPE of 1500-2500 J/kg. Isolated to widely scattered thunderstorm development appears possible by mid- to late afternoon along the high terrain within a kinematic environment featuring 30-35 kt westerly deep-layer shear. Transient supercell structures appear possible, which suggest some marginally severe hail potential, despite the warm mid-level temperatures. There is some model signal for storm clustering over the adjacent High Plains by evening, at which point the threat for isolated severe wind gusts would increase. ..Mead.. 07/27/2026 $$