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Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1229 PM CDT Fri Aug 16 2024

Valid 171200Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN PARTS OF KY/OH
VALLEY AND THE PACIFIC NORTHWEST...

...SUMMARY...
Scattered severe thunderstorms are possible in parts of Kentucky and
the Ohio Valley on Saturday afternoon through about dusk. Damaging
winds and hail are the primary threats. Isolated to scattered severe
wind and hail are also possible across parts of western Oregon into
southwest Washington on Saturday afternoon through about dusk.

...Lower Great Lakes to the Mid/Deep South...
A slow-moving mid/upper trough should continue east across the
Great Lakes through early Sunday. An occluded surface cyclone over
Lower MI should drift into Lake Huron. A weak cold front will arc to
the south-southwest over the Upper OH Valley and trail southwest to
west across the Mid-South into OK. Along this baroclinic zone,
ongoing convection at 12Z Saturday appears most probable over the
Ozarks vicinity. It is plausible this activity may intensify as
downstream diurnal destabilization occurs in the Mid to Deep South.
Within the mid-level flow gradient, semi-organized clusters are
possible with a threat for sporadic damaging winds.

The belt of seasonably strong mid to upper-level westerlies should
be centered across KY/TN within the basal portion of the Great Lakes
trough. Consensus of guidance suggests 700-mb westerlies will be
stronger relative to Friday, likely centered on the OH Valley
region. With the more prominent diurnal destabilization occurring
across KY into the OH Valley, away from the influence of Ozarks to
Deep South earlier-day convection, this setup may yield a greater
concentration of damaging winds and some severe hail along this
portion of the front. Despite the predominately westerly flow
regime, deep-layer speed shear should support a mix of multicell
clusters and semi-discrete, transient supercell structures. Multiple
convective rounds are possible during the afternoon into the early
to mid evening.

...Pacific Northwest...
A vigorous shortwave impulse, embedded within a broader mid/upper
trough, should move inland across northern CA into western OR. This
feature may take on a negative-tilt, with pronounced mid-level
height falls favorably timed to peak diurnal heating. A
strengthening mid to upper jetlet will overspread this region with
mid-level winds backing to the south-southeast. Within the exit
region of this meridional flow regime, scattered to numerous
late-afternoon and evening thunderstorms should be focused from
south to north across the Cascade Range. While buoyancy should
remain weak, steep mid to low-level lapse rates should support a few
supercells capable of both severe hail and wind. The wind threat may
be relatively greater across parts of the Columbia Valley near the
OR/WA border area as storms cluster into the early evening.

...Eastern Great Basin...
A plume of richer 700-mb moisture will advect north from AZ, with
peripheral flow enhancement from the West Coast shortwave trough.
Guidance is fairly consistent that late morning to midday
thunderstorm activity will increase as diurnal destabilization
ensues. While this may not be favorably timed with peak heating, the
steep lapse-rate environment and moderate deep-layer flow suggest a
threat for strong to sporadic severe gusts and small hail. A later
round of late afternoon to early evening thunderstorms may occur
along the western periphery of this earlier day activity, with a
similar threat for low-probability severe.

...Central and northern High Plains...
Mid-level ridging is expected across this region between the Great
Lakes and West Coast trough, but with moderate mid to upper-level
westerlies. Very isolated thunderstorms are possible during the late
afternoon to early evening along portions of a lee surface trough.
These appear most probable along the northwest periphery of the
central Great Plains to Ozarks buoyancy plume, in vicinity of
northwest KS, and separately near the Canadian border as a minor
shortwave impulse crests the ridge in the southern Prairie
Provinces. Deep-layer shear will be adequate for a couple supercells
capable of very isolated severe hail and wind.

..Grams.. 08/16/2024