ACUS11 KWNS 010844
SWOMCD
SPC MCD 010844=20
INZ000-ILZ000-IAZ000-011115-
Mesoscale Discussion 1623
NWS Storm Prediction Center Norman OK
0344 AM CDT Mon Aug 01 2022
Areas affected...a small portion of southeastern Iowa...central
Illinois and west central Indiana
Concerning...Severe potential...Watch unlikely=20
Valid 010844Z - 011115Z
Probability of Watch Issuance...20 percent
SUMMARY...One or two clusters of strong thunderstorms may be
maintained southeastward across the region through daybreak, perhaps accompanied by occasional surface gusts approaching severe limits.
DISCUSSION...Large-scale forcing for ascent associated with a
notable short wave trough digging through the Upper Midwest has
contributed to a southeastward propagating area of sustained
vigorous thunderstorm development the past several hours. The
primary cluster has been focused and rooted within an area of
enhanced low-level warm advection now spreading southeast of the
Mississippi River into north central Illinois. More recently,
thunderstorms are initiating near the intersection of trailing
associated outflow, and the leading edge of low-level cooling/drying
associated with the upper impulse. This is also generally near the
exit region of a digging 30-50 kt northwesterly jet streak (within
the 850-500 mb layer).
Various model output, including the latest High Resolution Rapid
Refresh, suggests that this forcing may maintain activity
east-southeastward across at least much of north central Illinois
and west central Indiana by 12-13Z. Storms appear largely rooted
above at least a couple thousand feet deep surface-based stable
layer, with moist elevated inflow characterized by moderately large
CAPE, though cloud-bearing layer shear may only be marginally
sufficient for organized convection.
Despite the strong rear inflow evident in radar data, the weakly
unstable to stable low-level lapse rates may be inhibiting downward
momentum transport to some degree, and there has been little
evidence of strong gusts in surface observations as activity tracks southeastward around 35 kt. However, it is possible that heavy
precipitation loading could support occasional, localized strong
surface gusts approaching severe limits as long as convection
maintains current strength.
..Kerr/Thompson.. 08/01/2022
...Please see
https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj= g!61M0W_z3Ze8rhROTH3gxFDqNAtEtG9z1eS7AvpO81qkIYT4xtZuo0z_FB1JnD73Ddj2aegiZd= BilAbYVsQBiTJHqKqU$ for graphic product...
ATTN...WFO...IND...LOT...ILX...DVN...
LAT...LON 40868943 41108877 39948681 38868717 39818989 41279153
40868943=20
=3D =3D =3D
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