SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0249 PM CDT Sun Oct 23 2022 Valid 232000Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS AND UPPER MIDWEST... ...SUMMARY... Thunderstorms capable of severe wind gusts and hail are possible from parts of the central Plains to Upper Midwest through tonight. ...20z Update... An increasing cumulus field and isolated thunderstorm is noted across parts of northern KS into southern NE at 1945z, indicating increasing ascent and modest destabilization. Surface dewpoints have mixed out into the 30s and 40s F across this area, but just downstream toward the MO River Valley, dewpoints are in the low/mid 50s F. Capping remains further east, but this should continue to decrease as large-scale ascent increases with time, and warm air advection continues ahead of the surface cold front. Thunderstorm coverage and accompanying severe potential should increase by 21-23z, posing a threat for strong/damaging gusts into the evening/overnight. No changes have been made to the ongoing outlook across the central Plains/Upper Midwest. Additional thunderstorm development is still expected across parts of the southern Plains near the end of the period. Strong gusts and perhaps small hail may accompany this activity over parts of northwest TX into southwest OK, mainly after 09z. No changes have been made to this portion of the outlook. ..Leitman.. 10/23/2022 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Oct 23 2022/ ...Central Plains to Upper Midwest... A prominent western states upper trough continues to evolve/amplify over the Rockies and Four Corners, with a strong mid/upper-level jet expected to develop northeastward from Arizona/New Mexico across the central Plains toward the Upper Midwest. Lee-side cyclogenesis will continue to occur initially across the central Plains while transitioning northeastward toward the eastern Dakotas tonight as a cold front begins to accelerate eastward across the central Plains/Upper Midwest. Modest autumnal low-level moisture will continue to stream northward and become increasing established within the warm sector ahead of the cold front, and more so, the preceding dryline across the central/southern Plains, although mixing (and some possible surface dewpoint reduction) will also occur as the boundary layer warms through peak heating. Isolated to widely scattered thunderstorms are expected along/ahead of the combined cold front/dryline as early as late afternoon, but more so toward/after sunset. Any surface-based thunderstorms will have the potential for isolated severe hail and wind gusts, given supercell-favorable vertical shear and fast storm motion atop a residually well-mixed warm-sector boundary layer. An increasing low-level jet (50-70 kt after 00Z) will enlarge low-level hodographs, with 30-35 kt shear-vector magnitudes in the effective-inflow layer, and effective SRH potentially in the 300-500 m2/s2 range. ...West-central/northwest Texas to southwest Oklahoma... Widely scattered to scattered thunderstorms are possible late tonight across this region, as the combined fronts overtake the dryline and impinge on increasing deep-layer moisture. Neither middle nor upper-level lapse rates are expected to be particularly steep. However, with increasing low-level moisture, and strengthening deep shear, an organizing band of convection may strengthen enough to produce a few embedded storms capable of isolated hail and/or wind gusts near severe limits.
