12AM Day 1 Convective Outlook for Friday, October 17. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF OK INTO CENTRAL/EASTERN KS AND WESTERN MO
SUMMARY
Thunderstorms with isolated hail and strong to severe wind gusts will be possible this evening through the overnight period from the southern and central Plains into the lower Missouri Valley.
Synopsis
A mid/upper-level cyclone initially near the ND/MB border will move northeastward through the day, as a trailing positive-tilt trough and attendant weak cold front move eastward across the Upper Midwest into the central/southern Great Plains. A mid/upper-level shortwave near the base of this trough is forecast to amplify by late in the period across the southern Rockies. Farther northwest, an upstream shortwave trough and vigorous mid/upper-level jet will dig southeastward across the northern Rockies late tonight.
Parts of the southern/central Plains into the lower MO Valley
Weak to locally moderate destabilization will be possible by late afternoon from parts of the southern/central Plains into the lower MO Valley, along/ahead of the weak surface trough/front. Generally weak midlevel lapse rates and modest large-scale ascent will tend to limit diurnal storm potential, but isolated strong-storm development cannot be ruled out by early evening. An increase in primarily elevated convection is expected from mid/late evening onward, in response to a nocturnally strengthening low-level jet, and eventual approach of the southern Rockies shortwave trough.
Increasing deep-layer flow/shear and some steepening of midlevel lapse rates late in the period will support potential for at least transient storm organization tonight, though guidance continues to vary regarding the coverage and intensity of overnight elevated convection. Isolated large hail and localized strong/damaging gusts will be possible with the strongest storms into early Saturday morning.