SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0234 AM CDT Tue Jun 25 2019 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTHERN MONTANA INTO WESTERN NORTH DAKOTA... ...SUMMARY... Scattered severe thunderstorms capable of large hail and strong wind gusts are possible across parts of northern Montana into western North Dakota on Thursday. ...Montana into the Upper Midwest... The upper low over the Pacific Northwest will continue to slowly pivot eastward on Thursday. Strong southwesterly flow aloft will overspread the northern Rockies while the Plains ridge drifts eastward. Low-level easterly flow across the northern Plains into MT will maintain 50s to low 60s surface dewpoints across eastern into north-central MT. High-based supercells will be possible in this moist, upslope regime. Similar to Day 2/Wednesday, vertical shear and elongated hodographs amidst very steep midlevel lapse rates will support very large hail in addition to damaging gusts. As a low-level jet increases overnight, some upscale growth and a continuation of severe potential could shift eastward into western North Dakota. The severe threat further east/southeast across the Dakotas into the Upper Midwest is a bit more uncertain/conditional. A very moist and unstable airmass will reside across the Mid-MO Valley into portions of southern MN/western WI. Some guidance suggests a potential MCV related to prior convection or weak shortwave impulse will top the ridge and shift southeast across this region. If this occurs, potential exists for the development of a severe MCS during the evening/overnight hours somewhere in the vicinity of MN/WI or perhaps eastern SD/NE into IA. Given uncertainty and conditional nature of the threat, have included Marginal risk probabilities, which may need to be adjusted depending on the evolution of convective systems over the next two days. ..Leitman.. 06/25/2019
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