Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Tue Jul 14 2020 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE MID-MISSISSIPPI VALLEY AND PARTS OF THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... Severe storms are expected on Wednesday across parts of the middle Mississippi Valley, and over portions of the central and southern High Plains. Damaging winds and hail will be the main hazards with these storms. ...Mid-MS Valley vicinity... An upper trough centered over the northern/central Plains Wednesday morning will shift eastward to the Great Lakes by Thursday morning. This will bring a belt of moderate southwesterly midlevel flow across portions of the lower MO/mid-MS Valleys to the Great Lakes. At the surface, a seasonally moist and unstable air mass will reside across the region ahead of a southeastward advancing cold front. Convection associated with one or more decaying MCSs from the Day 1/Tue period will likely be ongoing Wednesday morning from eastern KS/NE into parts of IA and perhaps MO. The location of this activity, how quickly it diminishes and/or lifts northeast, and any remnant boundaries/MCVs left behind will influence the breadth and location of afternoon convection. Most guidance suggests strong destabilization will occur across the mid-MS Valley vicinity from central MO into central IL along a sharp temperature gradient amid upper 60s to low 70s F surface dewpoints. Semi-discrete cells are possible initially with vertical wind profiles conducive of supercell structures. However, midlevel lapse rates will remain modest, and strong downburst winds appear possible given PW values near 2 inches. As frontal forcing increases and interactions among outflows occur, some upward development into one or more forward-propagating clusters/bowing line segments appears possible, especially as a southwesterly low level jet increases during the evening. Damaging wind will be the main hazard, though favorable vertical shear and instability could support severe hail in strongest cells. ...Southern/Central High Plains vicinity... A shortwave impulse will eject eastward across CO/NM Wednesday afternoon/evening. At the surface, moist upslope easterly low level flow will transport mid 50s to mid 60s F surface dewpoints westward across western KS, the OK/TX Panhandles and eastern CO/NM beneath steep midlevel lapse rates. Strong heating during the afternoon will result in thunderstorm development initially over the mountains. As storms move off higher terrain into the adjacent High Plains, vertically veering supercell wind profiles should aid in maintaining organized, albeit high-based, cells. There is some uncertainty regarding how far east convection will be maintained, as a stronger cap will be in place eastward toward the CO/KS border, extending southward into the OK/TX Panhandles. Nevertheless, isolated to scattered storms capable of strong winds, and perhaps hail, are expected along a narrow corridor from southeast CO into northeast NM and possibly parts of the OK/TX Panhandles. Some guidance develops storms northeastward along the surface cold front into northeast OK and southern KS overnight Wednesday/early Thursday. Forecast soundings suggest this activity would likely be elevated, but could pose at least a marginal threat of hail and gusty winds. ..Leitman.. 07/14/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_0600.html
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