SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1229 PM CDT Sat Jul 16 2022
Valid 171200Z - 181200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SUNDAY AFTERNOON
AND EVENING ACROSS PARTS OF THE LOWER OHIO VALLEY INTO ALLEGHENY
PLATEAU...OZARK PLATEAU/MID SOUTH...AND NORTHERN ROCKIES...
...SUMMARY...
Strong thunderstorms may impact parts of the Ohio Valley and
Allegheny Plateau into the Ozark Plateau and Mid South, as well as
portions of the northern Rockies vicinity Sunday afternoon and
evening, accompanied by at least some risk for damaging wind gusts.
...Synopsis...
Lower/mid-tropospheric ridging will generally be maintained from the
lower latitude western Atlantic through much of the U.S., including
a couple of prominent embedded mid-level high centers over the Four
Corners states and subtropical western Atlantic. Mid-level ridging
within the westerlies to the north of the Four Corners high may
become suppressed as far east as the northern Rockies, as a
mid-level low turns inland of the Pacific Northwest coast. To the
east of this ridging, a couple of digging perturbations may
contribute to the evolution of larger-scale mid-level troughing east
of the upper Mississippi Valley through the upper Ohio Valley and
lower Great Lakes, accompanied by influxes of cooler and/or drier
low-level air.
...Upper Ohio Valley into Allegheny Plateau...
Preceding one lead short wave perturbation within the evolving
larger-scale mid-level troughing, low-level moistening may
contribute to a corridor of mixed-layer CAPE on the order of
1000-2000 J/kg by Sunday afternoon with daytime heating.
Thermodynamic profiles may be characterized by generally modest to
weak lower/mid-tropopheric lapse rates and a high degree of
saturation. However, a corridor of stronger thunderstorm
development appears possible near the leading edge of the stronger
mid-level forcing for ascent, which may coincide with 30-40+ kt flow
on the southern fringe of the westerlies. This may be accompanied
by the evolution of a slow moving squall line with the potential to
produce damaging wind gusts, aided by heavy precipitation loading
and downward momentum transport, before convection weakens by Sunday
evening.
...Ozark Plateau/Mid South vicinity...
Severe probabilities have been adjusted some to more closely align
with a zone of stronger differential heating forecast to develop
beneath a plume of warm elevated mixed-layer air emanating from the
Great Plains. It remains unclear the extent to which forcing for
ascent associated with digging perturbations upstream of the
larger-scale mid-level trough axis will impact this developing
boundary, and low-level warm advection along it may remain weak.
However, given the presence of at least modestly steep mid-level
lapse rates, sizable CAPE in excess of 2000 J/kg, and modest
deep-layer shear, the environment probably will become at least
conditionally supportive of organized convection with the potential
to produce damaging wind gusts sometime late Sunday afternoon into
Sunday night.
...Northern Rockies...
Due to limited moisture, models suggest that CAPE may only reach 500
J/kg or so by late Sunday afternoon, within a deeply mixed boundary
layer across the higher terrain of southwestern into central
Montana. However, forcing for ascent, aided by orography,
downstream of the inland migrating low, coupled with shear beneath
30-50 kt flow in the 500-300 mb layer, might become conducive to
organized convective development spreading northeastward off the
higher terrain accompanied by potential to produce strong surface
gusts by Sunday evening.
..Kerr.. 07/16/2022
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