SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Thu Jul 08 2021 Valid 081200Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE NORTHERN GREAT PLAINS AND THE CAROLINA COAST... ...SUMMARY... Scattered severe thunderstorms capable of severe gusts and large hail are possible late this afternoon through the evening over the northern Great Plains. A couple of tornadoes are possible across the coastal Carolinas. ...Eastern MT into the Dakotas... A mid-level shortwave trough embedded within west-northwest flow is forecast to move from the northern Rockies into the Dakotas during the period. A frontal zone draped from northwest to southeast across the area will serve as a focus for thunderstorm development. Strong heating over far eastern MT into the western Dakotas will substantially erode convective inhibition by mid-late afternoon. Large-scale ascent attendant to the approaching speed max will promote scattered thunderstorms. Modest low-level moisture and relatively steep midlevel lapse rates will support moderate buoyancy. Models show long hodographs and this will favor supercells. Large to very large hail will likely accompany the supercells. Additional storms and a congealing of outflow during the evening may result in a cluster capable of a swath of severe gusts during the evening. If confidence increases, a probabilistic upgrade for hail and/or wind probabilities may occur in later outlooks. ...Coastal Carolinas into the Mid Atlantic... Some tornado threat will likely persist east of the track T.C. Elsa as it moves northeastward toward the Mid Atlantic coast. It seems sufficient buoyancy will reside near the immediate coast for a conditional risk for mesocyclones (embedded within a band or with discrete convection). As a result, a couple of tornadoes are possible in the moist/strong low-level shear environment. ...Portions of the Northeast/southern New England... Scattered thunderstorm development is expected by midday in a weakly capped environment across eastern PA and NJ, and also potentially along a warm front into portions of southern New England. Modestly enhanced southwesterly midlevel flow may support a few organized clusters capable of producing locally damaging wind. A transient supercell or two cannot be ruled out in the vicinity of the warm front, which would pose a threat of a tornado or two in addition the damaging wind potential. ...Lower Great Lakes/Ohio Valley... Scattered thunderstorms are expected by late morning/early afternoon along a cold front across portions of the lower Great Lakes and OH Valley. Weak midlevel lapse rates may tend to limit updraft intensity somewhat despite moderate buoyancy, but effective shear of 25-30 kt will support a few organized storms. Locally damaging wind is the most likely hazard with the strongest storms. ..Smith/Moore.. 07/08/2021 Read more LIVE: spc.noaa.gov
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