SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Wed Jun 23 2021 Valid 232000Z - 241200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING ACROSS CENTRAL NEBRASKA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN MN/WI INTO THE WESTERN U.P. OF MI... ...SUMMARY... Strong to severe storms are expected late this afternoon into tonight across parts of the central Plains and Upper Midwest. Damaging winds and large hail should be the main threats, with the greatest damaging wind threat expected across central Nebraska tonight. ...Nebraska and vicinity... The primary change for the 20Z outlook is to add a 10% significant wind area across portions of central NE. Development of a bowing complex still looks possible this evening, which would pose a threat of at least isolated significant (greater than 65 kt) wind gusts within a corridor of potentially damaging wind. The Marginal Risk has also been expanded somewhat to the north and east across southeast SD and western IA, in deference to some CAM guidance which suggests vigorous development is possible later tonight in these areas. ..Northern MN/WI... No changes have been made to this area. Widely scattered strong thunderstorms still appear possible by late afternoon along a cold front, and later tonight within a warm advection regime, posing a threat of large hail and damaging wind as convection spreads southeastward. ..Dean.. 06/23/2021 .PREV DISCUSSION... /ISSUED 1256 PM CDT Wed Jun 23 2021/ ...NE and vicinity... Morning water vapor loop shows an upper ridge over the central High Plains region. Model guidance indicates that midlevel heights will continue to rise across this area through mid-afternoon, until a weak shortwave trough over WY/CO tops the ridge and begins to move into western NE. This will be coincident with peak heating and scattered thunderstorm development. These storms will likely become severe by early evening and track across much of NE through the night. Convection is expected to grow upscale during this period, with a fast-moving bowing complex capable of damaging winds. Therefore, have added a small ENH for this threat. ...Northern MN/WI... A strong shortwave trough is digging southeastward across Saskatchewan toward the northern Plains. The associated surface cold front will sweep into ND/MN this evening, where scattered thunderstorm development is expected. These storms will track southeastward across northern MN through the evening, and into northern WI overnight. Low-level moisture will be slowly recovering in this region, with the greatest moisture/CAPE values remaining south of the SLGT risk area. Nevertheless, a few intense cells will be possible, capable of large hail and damaging winds. ...Southern MT into northeast WY... Strong heating is occurring today across southern MT into northeast WY, where dewpoints are in the 40s and afternoon MLCAPE values are forecast to approach 1000 J/kg. Forecast soundings indicate a deeply mixed boundary layer, along with relatively strong westerly flow aloft. This may result in a few thunderstorms capable of gusty/damaging winds this afternoon and early evening across the region. Read more LIVE: spc.noaa.gov
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