SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 PM CDT Tue Aug 09 2022
Valid 101200Z - 111200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WEDNESDAY
AFTERNOON AND EVENING ACROSS NORTHERN AND EASTERN VIRGINIA...CENTRAL
AND EASTERN MARYLAND...MUCH OF DELAWARE...CENTRAL AND EASTERN
WASHINGTON AND NORTHEASTERN OREGON...
...SUMMARY...
A cluster of strong thunderstorms, posing a risk for locally gusty
and damaging winds, may develop across parts of the Mid Atlantic
Wednesday afternoon and evening. Isolated strong thunderstorms may
also impact parts of the northern intermountain region, accompanied
by at least some risk for severe weather.
...Synopsis...
Little change to the amplified regime across the mid- and
subtropical latitudes of the eastern Pacific into the interior of
the U.S. is forecast through this period. Mid-level ridging, with a
broad and prominent embedded high, will remain centered across the
Rockies and Great Plains, downstream of large-scale troughing near
and offshore of the Pacific coast. Near and just east of the
mid-level trough axis, a significant embedded low appears likely to
continue migrating slowly northward just offshore of the Oregon and
Washington coasts.
To the east of the ridging, large-scale mid-level troughing, with a
couple of vigorous embedded perturbations, is forecast to gradually
dig across and southeast of the southern Hudson/James Bay and upper
Great Lakes vicinities. Models suggest that this will be preceded
by weak mid-level troughing digging southeast of the lower Great
Lakes through the Mid Atlantic vicinity by late Wednesday night.
In association with this regime, an initial cold front may gradually
stall and weaken across the Mid Atlantic coast and Ohio Valley into
Ozark Plateau and central Great Plains vicinity, as a reinforcing
cold front advances across much of the Great Lakes region by
daybreak Thursday. Seasonably high moisture content will largely
remain confined to the south of the lead front, to the east of the
Rockies. Across the west, a plume of monsoonal moisture emanating
from Southwest will be maintained, but perhaps slowly shift eastward
across the northern intermountain region/Great Basin, ahead of
subsidence/drying in the wake of the offshore low.
...Mid Atlantic...
As the surface front advances offshore of the northern Mid Atlantic
coast, models suggest that insolation across and to the lee of the
Blue Ridge may contribute to a zone of stronger differential surface
heating across the Potomac/Chesapeake vicinity Wednesday afternoon.
Despite rather weak deep-layer mean flow and shear, it is possible
that this boundary could provide a focus for consolidating
thunderstorm activity with some potential to organize by late
afternoon. Aided by inflow of seasonably moist boundary-layer air
characterized by CAPE on the order of 1000-2000+ J/kg, this
convection may generate outflow supportive of strong to severe
surface gusts, before weakening Wednesday evening.
...Washington/Oregon...
Uncertainty lingers concerning the extent and degree of appreciable
boundary-layer destabilization across the northern intermountain
region on Wednesday. However, aided by large-scale forcing for
ascent to the northeast through east of the northward migrating
offshore low, at least widely scattered thunderstorm development
appears possible Wednesday afternoon and evening, particularly off
the mountains of northeastern Oregon and near the higher terrain
north of the Columbia Plateau. Beneath 40-70+ kt southerly flow in
the 500-300 mb layer, forecast soundings indicate that hodographs
will become conditionally supportive of supercells posing at least a
risk for severe wind and hail.
..Kerr.. 08/09/2022
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