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Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1158 PM CDT Wed Jun 29 2022

Valid 011200Z - 021200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
WESTERN THROUGH SOUTHERN NEW YORK STATE...NORTHERN AND WESTERN
PENNSYLVANIA AND NORTHEASTERN OHIO....EAST CENTRAL KANSAS INTO WEST
CENTRAL MISSOURI...NORTHEASTERN WYOMING INTO SOUTHWESTERN SOUTH
DAKOTA AND NORTHWESTERN NEBRASKA...

...SUMMARY...
Widely scattered strong thunderstorms may impact parts of the
northern and central Great Plains and a corridor to the
east-southeast of the lower Great Lakes region late Friday afternoon
and evening, posing at least some risk for severe weather.

...Synopsis...
On the large scale, models continue to indicate that a prominent
blocking regime with amplified split flow will persist across the
eastern Pacific into western North America through this period and
beyond.  Downstream, broad mid-level troughing will be maintained
across much of Canada and the northern tier of the U.S. to the east
of the Rockies, with a deep embedded low of Arctic origins forecast
to slowly turn eastward across the southern Hudson/James Bay
vicinity.  Lower/mid-tropospheric ridging extending from the
southwestern Atlantic through the southern Rockies likely will also
be maintained, with mid-level ridging within the westerlies
persisting across the northern Rockies, downstream of the deepening
troughing offshore through inland of the U.S. Pacific coast.

An occluding surface cyclone, initially centered over southern
Hudson Bay by early Friday, may tend to develop to a position closer
to the mid-level low, while a secondary frontal wave forms across
northern Quebec into the Newfoundland and Labrador by late Friday
night.  While gradually stalling and weakening across parts of the
Ohio Valley into middle Mississippi Valley and Great Plains, the
trailing cold front may not advance southeast of the lower Great
Lakes and St. Lawrence Valley until Friday night.

Destabilization in a corridor along and south of the surface front
will provide one possible focus scattered thunderstorm development
Friday through Friday night.  However, due to a general lack of both
steeper mid-level lapse rates and more substantive low-level
moistening, most of the various model ensemble output suggest that
mixed-layer CAPE across most areas may only beco*e seasonably
modest, with the larger CAPE focused mostly south of the stronger
westerlies.  Furthermore, it appears that the pre-frontal 
southwesterly low-level flow will weaken from Thursday into Friday,
with the stronger deep-layer mean wind fields generally confined to
areas north of the international border.  However, spread within and
among the model output remains sizable, and there are probably at
least a few areas with at least low probabilities for severe
thunderstorm development.

...Lower Great Lakes into parts of the Allegheny Plateau...
While the cold front remains to the north of the region through the
day, at least some model output (perhaps most notably the NAM/NCEP
SREF) suggests that a pre-frontal return of lower/mid 60s+ F surface
dew points may contribute to mixed-layer CAPE in excess of 1000 J/kg
by late afternoon or early evening.  It appears that this may occur
as a perturbation within the cyclonic mid-level flow passes to the
north of the lower Great Lakes vicinity, and perhaps contributes to
strengthening westerly winds (on the order of 30-40 kt in the
700-500 mb layer) across the destabilizing environment.  This may
beco*e sufficient to contribute to the initiation of organizing
thunderstorm development by early Friday evening, if not earlier,
some of which might beco*e capable of producing marginally severe
wind and hail.

...Central Great Plains...
Models suggest that a corridor of stronger differential surface
heating and boundary-layer moistening may beco*e the focus for a
localized area of moderate to large CAPE (1500-3000 J/kg) by late
Friday afternoon.  Particularly where low-level convergence and warm
advection beco*e enhanced near a weak low, in the vicinity of the
intersection of the stalling surface front and the lee surface
troughing (somewhere across central to east central Kansas),
mid-level inhibition may erode sufficiently to allow for the
initiation of thunderstorms.  Wind fields may be generally weak, but
perhaps with sufficient shear to allow for isolated supercell
development, and possibly the evolution of a small cluster of storms
which could pose a risk for severe wind, in addition to hail, into
Friday evening.

...Northeastern Wyoming into areas near/south of Black Hills...
Low-level moistening may only allow for the development of modest
CAPE by late Friday afternoon.  But lower/mid tropospheric lapse
rates likely will beco*e steep, and forcing for ascent near and east
of a lee surface low, aided by low/mid-level warm advection, might
be sufficient to support thunderstorm initiation and an upscale
growing cluster of storms by Friday evening.  It appears there will
be sufficient deep-layer shear (aided by pronounced veering of winds
with height) to contribute to organization which may be acco*panied
by potential to produce severe winds, in addition to hail, before
weakening Friday night.

..Kerr.. 06/30/2022