SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sat Aug 21 2021 Valid 221200Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND CENTRAL PLAINS... ...SUMMARY... A few severe storms are expected across an area including parts of the central and northern Plains/Mid Missouri Valley region on Sunday. A brief tornado, and locally strong convective wind gusts, may also accompany the landfall of tropical system Henri into southeastern New York/southern New England. ...Synopsis... The upper flow field over the western U.S. will be characterized by persistent, longer-wavelength troughing, with a short-wave feature ejecting east-northeastward out of the Rockies and across the northern Plains, while a second trough/low digs southward out of western Canada toward/into the Pacific Northwest. A weak cold front associated with the ejecting northern Plains system will move eastward across the Plains through the period. East of the Rockies, ridging centered over the south-central U.S. will continue to prevail, while tropical system Henri affects the New England vicinity through the period. ...Parts of the central and northern Plains... Early/ongoing convection across portions of the outlook area may prove to be somewhat problematic with respect to evolution of the thermodynamic environment in some areas. Still, ample afternoon destabilization of a warm-sector airmass is expected across at least portions of Kansas and much of Nebraska, northward into the Dakotas. As the upper short-wave system crosses the Dakotas, convective redevelopment is expected. Weaker CAPE, but more favorably strong/veering flow aloft suggests at least some severe risk northward into North Dakota, while more unstable but somewhat less-sheared conditions favor more widespread storms farther south, with isolated, all-hazards severe potential. Given this potential, likely maximized through late afternoon/early evening before diminishing with diurnal stabilization, SLGT categorical risk will be maintained across this region. ...Long Island into southern New England... Tropical system Henri -- forecast by the latest NHC updates to move onshore over Long Island during the day Sunday -- will be accompanied by widespread strong winds and heavy rainfall. With little instability expected inland, thunderstorm activity in outer bands will likely be muted to some degree. Still, a few stronger convective cells in bands within the northeast quadrant of the storm may prove capable of convectively enhanced wind gusts, and possibly a brief tornado or two, through the period. ..Goss.. 08/21/2021 Read more LIVE: spc.noaa.gov
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