SPC May 23, 2020 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook
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Day 2 Convective Outlook NWS Storm Prediction Center Norman OK
Severe thunderstorms are possible across portions of the central
Plains, Middle Missouri Valley, and southern High Plains on Sunday.
Large hail and damaging wind gusts are the primary severe threats. ...Synopsis... An upper level trough centered over the Rockies Sunday morning will
shift eastward toward the Plains by Monday morning. Several
shortwave impulses are forecast to eject northeastward ahead of the
main trough, influencing convection from the southern High Plains
toward the mid-Missouri and upper-Mississippi Valley regions.
Overall, deep layer flow will not be particularly strong, but a belt
of 35-45 kt 700 mb flow will spread across portions of the
southern/central Plains to the Upper Midwest amidst weak height
falls. At the surface, a broad warm sector will exist to the east of a
dryline from western OK/TX, and ahead of a cold front from eastern
portions of the central Plains toward the Upper Midwest. Forecast
guidance varies greatly with regards to ongoing convection Sunday
morning -- some have it, some do not, and none forecast it in the
same place. There is also inconsistency in how much airmass recovery
will occur in areas that are affected by outflow from convection on
Saturday into early Sunday morning. As a result, considerable
uncertainty remains for Sunday severe potential and a broad Slight
risk is generally maintained with only minor changes from the
previous outlook. ...Central Plains to Upper Midwest... Strong heating of a very moist airmass with surface dewpoints in the
mid to upper 60s will result in strong destabilization during the
afternoon. A plume of steep midlevel lapse rates will exist across
the region, and MLCAPE as high as 2500-3500 J/kg is forecast in
areas unaffected by morning convection. Instability will be somewhat
less further north across southern MN into central WI where
dewpoints will be lower, but still sufficient for strong to severe
storms. Convection will develop ahead of an eastward advancing cold
front during the afternoon. Shear will be marginal, but adequate,
for supercells. Long, straight hodographs amidst steep lapse rates
suggest mainly potential for large hail. Given weak shear, any
initially discrete convection should trend toward clusters with
possibly some bowing segments developing through mergers/outflow
interactions. ...Southern Plains... The surface cold front will be located from central NE into western
KS and southeast CO Sunday morning. Post-frontal upslope flow will
allow high-based convection to develop near the higher terrain in
CO. As this convection moves east into the southern High Plains,
weak elevated instability and very steep midlevel lapse rates should
be sufficient in the presence of strong effective shear to support a
couple of severe storms capable of large hail. Additional storms are
expected to develop near a triple point near southwest KS and
southward along the dryline. Surface dewpoints in the mid 60s to
near 70 F and strong heating into the 80s will result in strong
destabilization and supercells are expected. Large hail and damaging
gusts will be the main concern. Convection is expected to quickly
transition toward bowing/linear segments as a low level jet
increases and frontal forcing increases. One of more bowing segments
could track eastward across western/central KS into western OK and
central/southern TX during the evening hours. Given aforementioned
uncertainties, how far east severe convection persists remains
uncertain. ...Eastern TX/western LA... Strong instability will be in place across the region as warm
advection spreads northward ahead of the Rockies/Plains upper
trough. Most guidance indicates an MCV migrating across the region,
which could lead to enhancement of low/mid level shear. As a result,
a few intense cells are expected and could producing strong, locally
damaging downburst winds. ..Leitman.. 05/23/2020 

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