SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0256 PM CDT Tue Jun 22 2021 Valid 222000Z - 231200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF IA AND EASTERN NE... ...SUMMARY... A few severe thunderstorms are possible later this afternoon into tonight over portions of Nebraska and Iowa. ...NE/IA... No changes have been made to the previous outlook. It still appears possible that a few strong storms will eventually develop across this region, possibly evolving from ongoing elevated convection. The strongest storms will be capable of large hail and locally damaging wind. See the previous discussion below for more details. ...Mid Atlantic to FL... The Marginal Risk has been trimmed to account for progression of ongoing storms and the stabilization in their wake. The greatest remaining threat for locally damaging wind appears to be across eastern NC and northeast SC ahead of a cold front, and near/south of ongoing convection across the northern FL Peninsula as it spreads southeastward. ...Elsewhere... No major changes have been made to the other portions of the outlook. See the previous discussion below for more information. ..Dean.. 06/22/2021 .PREV DISCUSSION... /ISSUED 1130 AM CDT Tue Jun 22 2021/ ...IA/NE... Morning surface analysis shows a quasi-stationary boundary along the NE/SD border. This boundary extends eastward into IA, but it is less defined. Model guidance suggests that the eastern extent will become better defined by late afternoon, with sufficient convergence to promote the risk of isolated thunderstorm development. Low-level moisture in this area is limited this morning, with dewpoints only in the mid 50s. Most model solutions suggest rapid dewpoint increases this afternoon, probably due to evapotranspiration and a shallow boundary-layer. However, it is unclear if models are handling this process very well. Current indications are that a few intense storms/supercells may develop, capable of large hail and gusty winds. However, if the cap is stronger or low-level moisture is weaker than forecast, coverage of activity could be very limited. ...Mid Atlantic Region to FL... A surface cold front continues to sag across the Mid-Atlantic region and southeast states. Rather widespread shower/thunderstorm activity and associated cloud cover is limiting instability ahead of the front. This suggests that the overall severe threat is MRGL. One area that may see a slightly greater risk of severe storms would be over the southeast VA vicinity. Please refer to MCD #1060 for further details. Another area of concern will be over the eastern FL peninsula, where westerly low-level winds will enhance convergence along the east-coast sea-breeze. This may result in a few strong/severe storms for a few hours this afternoon, capable of gusty/damaging wind gusts. ...Eastern NM... A few high-based thunderstorms are forecast to develop later this afternoon over the high plains of eastern NM. Inverted-v profiles and dewpoints in the 50s will promote a risk of gusty winds near the strongest cells. ...Eastern OR/Western ID... Similar to yesterday, scattered high-based thunderstorms are expected to develop this afternoon and evening over parts of central OR. A deeply-mixed boundary layer and sufficient CAPE for robust updrafts will pose a risk of gusty/damaging winds in the strongest cells. Read more LIVE: spc.noaa.gov
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