SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0105 AM CDT Fri Jun 04 2021 Valid 041200Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL/EASTERN MT...THE NORTHERN HALF OF ND...AND EXTREME NORTHWEST MN... ...SUMMARY... Severe thunderstorms will be possible across parts of Montana and North Dakota this afternoon and evening. Damaging wind gusts are expected to be the primary threat. ...Synopsis... The upper trough over the eastern CONUS is forecast to move offshore by tonight, while a weak mid/upper-level low is forecast to move little across TX. An upper ridge will remain in place across much of the West, though a midlevel shortwave trough is forecast to flatten the northern portion of the ridge as it moves across the northern Rockies/High Plains and Canadian Prairies. ...MT into ND/northwest MN... Multiple thunderstorm clusters may impact portions of central/eastern MT into ND/northwest MN this afternoon and evening, as the aforementioned shortwave trough approaches the region. One cluster may develop across the higher terrain and move east-northeastward across MT, while another may develop further east in association with a weak surface boundary and move eastward across much of ND into northwest MN. Midlevel flow/effective shear will be somewhat stronger across MT, and initial development there could pose some hail threat given steep midlevel lapse rates. However, the primary threat will be severe wind gusts, as one or more clusters move through a very hot and well-mixed environment across eastern MT into ND. Even as the boundary layer cools this evening, any remaining organized convection may still pose a severe-wind threat into portions of eastern ND and northern MN. ...Carolinas into the Mid Atlantic... Additional rounds of convection are expected today from the Mid Atlantic into the Carolinas, before the upper trough moves offshore this evening. Weak midlevel lapse rates may tend to limit updraft intensity, but effective shear will remain sufficient for occasionally organized cells or clusters, with primarily a damaging-wind threat. Somewhat steeper midlevel lapse rates may move into the Tidewater vicinity by this evening in association with the exiting upper trough, which may briefly intensity ongoing convection before increasing MLCINH and large-scale subsidence ends the threat later tonight. ..Dean/Squitieri.. 06/04/2021 Read more LIVE: spc.noaa.gov
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