Valid 220100Z – 221200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL
HIGH PLAINS TO THE LOWER OHIO VALLEY…
…SUMMARY…
Strong, isolated severe storms are possible this evening into the
overnight hours across parts of the High Plains into Kansas,
eastward toward southern Indiana and northern Kentucky. Strong
gusts will be the main concern, but some marginally severe hail is
possible as well.
…WY/CO High Plains eastward toward the Lower OH Valley…
Strong to isolated severe thunderstorms were ongoing this evening in
a modestly sheared, moderately unstable airmass. Several shortwave
impulses will continue to move through west/northwesterly flow from
the central High Plains toward the Midwest through the overnight
hours while a surface boundary extending across KS eastward into
MO/IL/IN remains nearly stationary. Warm advection atop the boundary
will result in elevated storms through the overnight hours. However,
modest effective shear (25-35 kt) and midlevel lapse rates (6.5-7
C/km per 00z regional RAOBs) should limit overall severe
potential/storm organization in the absence of a stronger developing
low level jet overnight.
Nevertheless, strong to isolated severe storms are possible in the
short term across the central High Plains where lapse rates are
steeper. Though this threat should wane over the next couple of
hours as the boundary layer stabilizes. Further east, storm clusters
may produce periods of strong gusts through storm mergers/outflow
interactions, but overall severe threat should remain limited by
elevated nature of the convection.
…Northeastern States…
The severe threat will continue to quickly diminish this evening as
storms approach and move off the coast. Additionally, the boundary
layer will continue to stabilize with the loss of daytime heating
and subtle forcing continues to weaken as the shortwave impulse
lifts northeast of the region. A couple of strong storms may persist
the next hour or so, but the overall threat has diminished
sufficiently to remove severe probabilities this evening.
..Leitman.. 08/22/2019
$$