Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1243 AM CDT Thu Jun 25 2020 Valid 251200Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE NORTH-CENTRAL STATES... ...SUMMARY... Scattered strong/severe thunderstorms are expected across parts of the north-central States later this afternoon and evening. Damaging winds and hail are the primary threats. ...North-Central States... Weak mid-level height falls will spread across the northern Rockies into the northern Plains later today ahead of a short-wave trough that should extend across eastern MT/northwestern WY by 26/00z. At low levels, a surface front will surge into the central Dakotas by early afternoon, and this boundary should provide the focus for scattered thunderstorm development. Latest model guidance suggests low-level convergence will not be particularly strong along the front, but likely adequate for thunderstorm initiation after 21z as surface parcels reach their convective temperatures in the mid-upper 80s. While weak convection will likely be ongoing at the start of the period ahead of an upper vort near the international border, diurnal heating will prove instrumental in potential severe due to substantial inhibition. Forecast soundings suggest deep-layer wind profiles are more than adequate for potential supercells, and initial activity will likely be discrete in nature. However, aforementioned weak low-level convergence will likely lead to storm mergers during the evening and a more complex storm mode should ultimately evolve. Latest CAMs support this and wind/hail are the primary risks. Upstream across WY, a secondary mid-level disturbance should aid convection across higher elevations/High Plains region. This activity will propagate toward the NE Panhandle after sunset as the front settles into this portion of the central Plains. ...Southern Middle Atlantic/Carolinas... Great Lakes/OH Valley upper trough will shift east of the Appalachians during the latter half of the period. Latest guidance suggests lee trough will evolve across VA/NC and this boundary is expected to enhance the possibility for at least isolated afternoon thunderstorms as surface temperatures warm to near 80F. Modest surface-6km shear would seem supportive of a few robust updrafts capable of producing gusty winds, and perhaps some hail across the Middle Atlantic region. Farther south across the Carolinas, several weak disturbances are embedded within westerly flow along the southern fringe of the larger trough. Latest radar data depicts one of these features over western GA and another shearing east along the central Gulf Coast. Each of these features should encourage convection immediately downstream, especially as boundary layer warms by mid day. Even so, poor lapse rates and weak shear do not look particularly favorable for more than low wind probs. ..Darrow/Squitieri.. 06/25/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
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