Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Detroit, MI...Milwaukee, WI...Denver, CO...Kansas City, MO...Cleveland, OH...
SPC AC 271622
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Mon May 27 2019
Valid 271630Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FOR NORTHERN IL/IN AND VICINITY...AS WELL AS THE
NORTHEASTERN CO/SOUTHWESTERN NE AREA...
Severe thunderstorms, including a risk for tornadoes, severe hail
and damaging wind gusts, are expected across the Midwest this
afternoon into tonight including eastern Iowa to northern portions
of Illinois/Indiana. Severe storms are also expected across the
central High Plains, and perhaps southward through the Texas South
Plains on a more isolated basis.
...Northern IL/IN this afternoon into early tonight...
A convectively-enhanced midlevel trough over northwestern IA will
crest the midlevel ridge over the MS Valley and begin to move more
eastward this afternoon into this evening. Enhanced low-midlevel
southwesterly flow (up to 60 kt per regional VWPs) on the
southeastern flank of the trough/MCV will overspread the surface
warm front and destabilizing warm sector from eastern IA across
northern IL this afternoon. Per 12z soundings, midlevel lapse rates
are not steep as a result of widespread prior convection across the
central Plains, but the cap is also not strong. Daytime heating in
the wake of ongoing convection in northwestern IL, and northward
advection of richer low-level moisture from southern/central IL,
will contribute to moderate buoyancy (MLCAPE of 1500-2000 J/kg) by
mid afternoon, when surface-based thunderstorm development is
Both effective bulk shear and 0-1 km SRH will be well into the
supercell/tornado parameter space (greater than 50 kt and 200 m2/s2,
respectively) in the moist low-level environment. Thus, a few
supercells appear likely, with the potential to produce isolated
strong tornadoes. The storms will spread eastward from IL into
northern IN through this evening, with a continued tornado threat
into early tonight. Damaging winds will become more probable this
evening if any upscale growth into clusters occur, while the
supercells will also be capable of producing large hail.
...Central High Plains this afternoon into tonight...
A deep midlevel low over the southern Great Basin will pivot
northeastward toward CO tonight, as associated lee cyclogenesis
occurs across eastern CO. Low-level moisture has been reduced
across the central Plains in the wake of widespread overnight
convection, with boundary-layer dewpoints generally limited to the
low-mid 50s. However, daytime heating beneath steep midlevel lapse
rates will contribute to moderate buoyancy (MLCAPE of 1000-1500
J/kg) this afternoon across far southwestern NE, southeastern WY and
northeastern into north central CO.
Strengthening low-level upslope flow and background ascent within
the left-exit region of the mid-upper jet will promote thunderstorm
development by mid afternoon near the front range from Denver to
Laramie, as well as near the triple point in northeastern CO.
Storms will subsequently spread eastward through the evening into
early tonight along and immediately north of an east-west front.
Wind profiles will favor supercells with very large hail, as well as
a couple of tornadoes, with damaging winds and some upscale growth
into a cluster possible tonight across NE.
...Eastern TX Panhandle and vicinity this evening...
The dryline will sharpen this afternoon across the TX Panhandle, and
will likely retreat some to the west this evening. Though forcing
for ascent will not be strong, weak midlevel height falls are
expected, and low-midlevel flow will have enough southerly component
to allow reasonably long residence time for parcels within the
dryline circulation. Thus, will extend the SLGT risk southward to
account for isolated storm development this evening (and perhaps
some convection overnight), and the conditional threat for
supercells with large hail and perhaps a tornado.
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