SPC Aug 26, 2020 0100 UTC Day 1 Convective Outlook

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0752 PM CDT Tue Aug 25 2020

Valid 260100Z - 261200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL APPALACHIANS AND MID-ATLANTIC...

...SUMMARY...
Thunderstorms associated with damaging wind gusts will remain the
primary severe threat for parts of the central Appalachians and
Mid-Atlantic this evening.

...Central Appalachians/Mid-Atlantic...
The latest radar imagery shows a multi-segmented line of storms from
far eastern Kentucky extending eastward to south of Washington D.C.
This line will continue to move southward into a moderately unstable
airmass where surface dewpoints are in the lower to mid 70s F. The
moisture and instability combined with steep low-level lapse rates
will be favorable for damaging wind gusts along the leading edge of
the more intense line segments...see MCD 1577. The severe threat
should become marginal late this evening as instability decreases
across the region.

...Northern Plains/Upper Mississippi Valley...
An upper-level ridge will move across the upper Mississippi Valley
this evening. Beneath the ridge, a moist and unstable airmass is
present from parts of the northern Plains extending eastward into
central Minnesota and northern Wisconsin. Although large-scale
ascent will be limited due to the presence of the ridge, low-level
flow will dramatically increase this evening. In response, isolated
thunderstorms, elevated in nature, may form across parts of the
Dakotas and Minnesota. Any storm that can develop and persist could
have a potential for strong wind gusts and hail.

...Northern Rockies...
The latest water vapor imagery shows west-southwest mid-level flow
in place across the northwestern U.S. Surface dewpoints across much
of the northern Rockies are in the 50s F, which has enabled a pocket
of instability to develop from parts of Idaho northward into western
Montana. As thunderstorms move northeastward across the northern
Rockies, the instability combined with moderate deep-layer shear and
steep mid-level lapse rates may be enough for a marginal wind damage
threat...see MCD 1576.

...Arizona...
Scattered thunderstorms are ongoing across the southern half of
Arizona early this evening. Although instability is weak across most
of southern and central Arizona, lapse rates are very steep
according to RAP analysis and the Tucson 00Z sounding. This
thermodynamic environment may be enough for a marginal wind damage
threat with the stronger cells this evening. Any wind damage threat
should diminish over the next couple of hours.

..Broyles.. 08/26/2020

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from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_0100.html