Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 2 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
5 %
409,575
76,059,371
New York, NY...Philadelphia, PA...Columbus, OH...Memphis, TN...Baltimore, MD...
Probabilistic Large Hail Graphic
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Fort Collins, CO...Longmont, CO...Loveland, CO...Brighton, CO...Laramie, WY...
SPC AC 120548
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Thu Aug 12 2021
Valid 131200Z - 141200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF THE NORTHEAST STATES INTO THE OHIO...TENNESSEE AND LOWER
MISSISSIPPI VALLEYS...
...SUMMARY...
A few strong to severe storms with locally strong to damaging wind
gusts will be possible from a portion of the Northeast States into
the Ohio, Tennessee and lower Mississippi Valleys Friday.
...Northeast States through the Ohio, Tennessee and lower
Mississippi Valleys...
A broad upper trough will persist over the Great Lakes region. By
12Z Friday a cold front should extend from the lower Great Lakes
through northern or central IL then westward into KS. A moist
boundary layer will reside in the pre-frontal warm sector. However,
there will likely be areas of ongoing thunderstorms and widespread
convective debris over portions of this region. There also remains
uncertainty where the convective boundaries and MCVs associated any
ongoing activity will situated, but current indications are that the
outflow boundaries will likely result in the more unstable portion
of the warm sector evolving well south of the synoptic front. The
atmosphere should become moderately unstable during the afternoon,
and additional thunderstorms will redevelop primarily along residual
outflow boundaries. Vertical shear in the warm sector will remain
weak and supportive of multicells, but storms may evolve into lines
and clusters and become capable of producing isolated strong to
severe gusts through early evening.
...Central High Plains...
A post-frontal upslope flow regime will evolve Friday, resulting in
a corridor of upper 50s to 60F dewpoints advecting northwestward
into northeast CO and southeast WY beneath steeper mid-level lapse
rates. The atmosphere may become at least marginally unstable in
this region with 500-1000 J/kg MLCAPE possible. Isolated storms may
develop over the higher terrain and spread southeast. Weak to modest
0-6 km shear of 25-35 kt will support multicell storms. The stronger
updrafts could produce a few instances of marginally severe hail.
..Dial.. 08/12/2021
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
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