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 1 Wind Risk
Area (sq. mi.)
Some Larger Population Centers in Risk Area
Green Bay, WI...Appleton, WI...Oshkosh, WI...La Crosse, WI...Sheboygan, WI...
SPC AC 062003
Day 1 Convective Outlook CORR 1
NWS Storm Prediction Center Norman OK
0303 PM CDT Thu Jul 06 2017
Valid 062000Z - 071200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
WISCONSIN AND NORTHERN LOWER MICHIGAN...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED RISK ACROSS MUCH OF THE WESTERN AND CENTRAL GREAT LAKES
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
CAROLINAS PIEDMONT SOUTHWESTWARD INTO NORTHERN GEORGIA...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK ACROSS MUCH OF THE WESTERN AND CENTRAL GREAT LAKES
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE
ARKLAMISS NORTHEASTWARD TO THE CAROLINAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS A PORTION
OF THE ROCKIES AND INTO THE CENTRAL HIGH PLAINS...
CORRECTED FOR NDFD GRID ERROR
Severe storms with a threat for large hail and damaging wind are
expected from a portion of the upper Mississippi Valley into the
Great Lakes today. Other storms with locally damaging wind gusts
are possible from the Tennessee Valley to North Carolina and
Virginia Thursday afternoon. An isolated severe hail/wind threat
also extends from southern Nebraska to eastern Wyoming, northeastern
Colorado, and southeast Montana.
The overall forecast philosophy from the 1630Z outlook is generally
on track, although with a few changes:
1) A couple of linear segments have organized across northern
Georgia, and at least one of these segments has produced localized
wind damage. This threat will persist into upstate South Carolina a
bit south of areas indicated by previous guidance, and there are
some indications that this threat will persist even farther
downstream into central North Carolina through sunset. 5%/marginal
probabilities have been expanded, and a slight risk has been
introduced across the Carolinas Piedmont into northern Georgia with
the expectation that scattered wind damage/severe wind gusts will
occur in these areas.
2) A cluster of storms has developed just northwest of the Arrowhead
of Minnesota, and a cumulus field has increase in satellite to the
southwest of these storms and very near a surface trough migrating
through that region. Latest high-resolution guidance suggests that
storms may initiate in northeastern Minnesota and spread
southeastward into a moderately unstable environment with 40+ knots
of deep shear. Given the latest trends, 5%/marginal probabilities
for wind and hail have been added to northeastern Minnesota, and
higher probabilities are retained downstream despite some concerns
about eventual convective coverage through the evening. 2% tornado
probabilities have also been expanded northwestward as an isolated
tornado cannot be ruled out in areas downstream of initial
development in northeastern Minnesota.
.PREV DISCUSSION... /ISSUED 1124 AM CDT Thu Jul 06 2017/
...Upper MS Valley and western Great Lakes...
This morning's water vapor loop shows a shortwave trough moving
across the MN Arrowhead. This feature will continue southwestward
this afternoon and aid in the development of afternoon thunderstorms
over parts of MN/WI/MI. Surface dewpoints in the mid/upper 60s and
strong heating will combine with steep mid level lapse rates to
yield strong CAPE values this afternoon. Forecast soundings also
show strengthening wind fields through the day, with effective shear
becoming favorable for supercell and bowing structures. 12z CAM
solutions lack consistency in the location/timing of initiation, but
generally agree that intense storms will affect the region later
today. Large (potentially very large) hail and damaging winds are
the main threats, with some concern for upscale growth and more
widespread wind damage this evening as storms move across the ENH
...Gulf Coast states into Mid Atlantic...
Visible satellite imagery suggests strong heating will occur across
a broad corridor from MS to VA today, with low and mid level wind
fields slightly stronger than yesterday. It appears likely that
pockets of strong instability will develop, promoting scattered
afternoon thunderstorms. Larger-scale forcing mechanisms are hard
to find, but eventually this region will likely see multiple
clusters of storms capable of locally gusty/damaging wind gusts. If
these mesoscale areas of greater risk can be identified later today,
portions of this corridor will be considered for an upgrade to SLGT
...MT into NE...
Widely scattered thunderstorms are expected this afternoon over the
northern and central High Plains region, on the east side of a
developing upper ridge. The strongest cells in this area may
produce hail and gusty winds for a few hours this evening.
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z