Day 1 Severe Weather Outlook

Valid 281630Z – 291200Z


The threat for severe thunderstorms, with large hail as the primary
threat, appears most concentrated during the late afternoon and
early evening over parts of eastern Kansas and western Missouri.

…Eastern KS and western MO vicinity…
A low-amplitude shortwave impulse near the north-central
OK/south-central KS border will track northeast towards the Mid-MS
Valley. A quasi-stationary front extends across east-central KS to
northeast MO downstream of a weak surface cyclone that is expected
to undergo cyclolysis. Differential heating across the front amid
persistent, but weak low-level southerlies should support late
afternoon to early evening scattered storm development along and to
the cool side of the front. The aforementioned weak low-level winds
should limit hodograph curvature, but adequate mid to upper-level
speed shear should foster a few rotating updrafts. Residual steep
mid-level lapse rates as sampled by 12Z Norman and Lamont, OK
observed soundings will foster a level 2-Slight risk for hail with
locally severe wind gusts possible as well.

…TX Panhandle vicinity…
Trailing portion of the Great Plains quasi-stationary front
currently bisects the Panhandle. This feature should be the focus
for late afternoon thunderstorm development near its intersection
with the dryline in far east-central NM. Weak forcing for ascent
coupled with 35-40 kt effective shear may foster a couple discrete
supercells. The primary uncertainty is the coverage of any
individual severe hazard. Mid-level lapse rates will be modest amid
weak height rises, which will be a limiting factor to hail growth.
In addition, a recently decayed gravity wave pushed richer
boundary-layer moisture southeast of an Abilene to Wichita Falls
line, which suggests guidance might be a bit too aggressive with the
degree of buoyancy return by 00Z. A strengthening low-level jet this
evening could still be enough to yield a small cluster with isolated
severe wind gusts.

A remnant convectively induced mid-level impulse near the IN/MI/OH
border will progress east. This feature will aid in isolated to
scattered late afternoon and early evening storm development across
mainly PA into southern NY and NJ. The combination of buoyancy and
deep-layer shear should be modest amid weak mid-level lapse rates.
However, steep low-level lapse rates will support a risk for locally
strong gusts and damaging winds given near-record to record warm

…Northern UT to central WY…
Although buoyancy should remain meager, occasional thunderstorms
will persist along a pronounced baroclinic zone/differential heating
corridor into this evening. Fast mid-level southwesterlies will
support marginally severe hail and locally severe wind gusts.

..Grams/Elliott.. 09/28/2019


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