SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1223 AM CDT Fri Oct 15 2021 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM ARKANSAS ACROSS THE OHIO VALLEY INTO WESTERN NEW YORK... ...SUMMARY... Isolated severe thunderstorms are expected today from Arkansas, northeast across the Ohio Valley into western New York. Gusty winds, marginally severe hail, and one or two tornadoes are possible. ...Lower MS Valley to Western NY... Broad area of mid-level height falls will spread across the mid/upper MS Valley and OH Valley regions ahead of a progressive trough during the day1 period. This feature is currently advancing across the High Plains with the strongest jet core extending through the base of the trough over NM, into the upper Great Lakes. Leading edge of forcing has recently aided strong thunderstorm development across central OK, and this activity should spread east-northeast toward the Ozark Plateau early in the period. While convection may be robust at daybreak, current thinking is seasonally strong boundary-layer heating across the lower MS Valley should aid buoyancy ahead of the cold front. Renewed thunderstorm development is expected across the lower MS Valley ahead of the front as boundary layer warms/destabilizes. Have extended SLGT Risk a bit farther south into this region to account for strong/severe thunderstorms that should evolve by early afternoon. These storms should propagate east toward middle TN by early evening. Forecast soundings suggest ample deep-layer flow for supercells, and low-level shear may be strong enough for one or two tornadoes. Farther north across the OH Valley into western NY, LLJ is forecast to increase ahead of an embedded short-wave trough within the larger trough. Resultant low-level shear will strengthen across OH by mid day, and over the lower Great Lakes region by early evening ahead of the main surface low. This cyclone is forecast to track from central OH to Lake ON by 16/06z, then into southwest QC by the end of the period. Frontal convection will be common ahead of this system given the seasonally high PW immediately ahead of the wind shift. While gusty winds are the main threat, a few supercells are expected ahead of the surface low where shear will be maximized. Have increased tornado probabilities a bit into western NY to account for more destabilization across this region than earlier anticipated. ..Darrow/Wendt.. 10/15/2021 Read more LIVE: spc.noaa.gov
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