SPC AC 132031
Day 1 Convective Outlook CORR 2
NWS Storm Prediction Center Norman OK
0331 PM CDT Fri May 13 2022
Valid 132000Z - 141200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS CENTRAL OKLAHOMA
TO FAR SOUTHERN KANSAS AND THE UPPER MISSISSIPPI RIVER VALLEY...
CORRECTED FOR GENERAL THUNDER LINE
...SUMMARY...
Isolated to scattered severe thunderstorms will be possible later
this afternoon through this evening across a large portion of the
central states. The most probable areas for large hail and damaging
winds are across a portion of Oklahoma and southern Kansas, as well
as from east-central Missouri to southwest Wisconsin.
...Discussion...
The forecast generally remains on track with only minor adjustments
required. Latest analyses and observations from central/southern OK
show cool outflow from morning/ongoing convection lingers across the
region with only modest recovery. Consequently, low-level lapse
rates remain somewhat poor and may not recover sufficiently to
support a widespread damaging wind threat. As a result, the 15% wind
risk area is removed. However, thunderstorms developing this
afternoon/evening will still pose a large hail risk with an
attendant (albeit limited) damaging wind potential.
Across the upper MS river valley, latest GOES visible imagery shows
cumulus beginning to deepen along the surface cold front from
northern IL into WI. Low-level lapse rates in the region continue to
steepen to near 8 C/km, which will support a damaging wind threat as
storms develop along the front around late afternoon.
..Moore/Mosier.. 05/13/2022
.PREV DISCUSSION... /ISSUED 1126 AM CDT Fri May 13 2022/
...OK to southern KS...
Below-average confidence exists in how convective evolution will
play out late this afternoon and evening. A quasi-stationary
thunderstorm cluster has been persistent in a portion of
east-central to northeast OK. While most 12Z guidance suggest this
activity should gradually drift east and weaken this afternoon, some
CAMs indicate renewed storm development will occur along its
southwest flank in the south-central OK vicinity later this
afternoon when differential heating should be maximized. Other
guidance suggests convection will also develop farther
west-northwest along the weakly convergent surface front in
south-central KS to west-central OK during the 00-02Z time frame.
Given weak low-level winds and nebulous large-scale ascent, these
various scenarios appear plausible. Within a belt of 25-30 kt 500-mb
westerlies, a few slow-moving supercells and multicell clusters may
develop with large hail and damaging winds as the primary hazards.
...WI to the Mid-MS Valley...
An MCV near the MO/IA border should shift northeast into WI by this
evening. A surface cold front will move east across WI and trail
south-southwest into the Mid-MS Valley. Convergence along this
boundary will be the primary forcing mechanism for a broken band of
thunderstorms during the 23-02Z time frame. A relatively narrow
plume of higher PW values evidenced in GOES imagery should be
confined to along the surface boundary from the Mid-MO Valley south.
Weak shear is expected in this region but should be compensated by
larger buoyancy. The trailing influence of enhanced deep-layer shear
attendant to the MCV should affect the WI/IA/IL border area north
where MLCAPE will be subdued. Overall scenario suggests multicell
clustering will dominate with a confined threat for isolated to
scattered damaging winds and isolated severe hail.
...Lower MS Valley...
Along a diffuse front aiding in low-level convergence, ongoing
thunderstorms across western MS should expand in coverage from the
AR/TN border south into southeast LA during the rest of the
afternoon. Vertical shear will be weak, but a belt of 20-25-kt
mid-level northerlies will support some multicell clustering.
Localized damaging winds from wet microbursts will be the primary
hazard, but isolated marginally severe hail will be possible as
well.
...West TX...
Hot temperatures to the west of the dryline will aid in scattered
thunderstorms along the boundary during the late afternoon to early
evening. Weak lower-level wind fields will minimize SRH, but
sufficient deep-layer shear will exist for a few transient
supercells and multicell clusters capable of isolated large hail and
severe wind gusts.
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