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
Rapid City, SD...Cheyenne, WY...Casper, WY...Laramie, WY...Garden City, KS...
SPC AC 271959
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun May 27 2018
Valid 272000Z - 281200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST NEBRASKA...FAR EASTERN COLORADO...WESTERN KANSAS AND THE
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE HIGH PLAINS AND NORTHERN ROCKIES...
Severe storms with large hail and wind damage are possible late this
afternoon into this evening across parts of the high Plains. A few
tornadoes may occur across the Florida Peninsula.
Several changes have been made to the outlook for this issuance. The
first change to the outlook is to add an enhanced risk area to parts
of far eastern Colorado, southwest Nebraska, western Kansas and the
Oklahoma Panhandle. Confidence has increased that storms will be
numerous enough to warrant adding a narrow corridor for 30 percent
hail coverage where the storms are expected to interact with strong
instability late this afternoon. The second change to the outlook is
to expand the slight risk area westward across west-central Wyoming
where strong to severe storms are ongoing. The third change to the
outlook is to expand the marginal risk area across lower Michigan
northward to a cold front where several severe storms are also
.PREV DISCUSSION... /ISSUED 1125 AM CDT Sun May 27 2018/
A large upper low is positioned over NV today, with multiple
shortwave troughs rotating around the trough into the central
Rockies. Models are very consistent in the development of a band of
thunderstorms this afternoon across southern WY arcing into
northeast CO. These storms are expected to spread northward through
the evening into parts of western SD and western NE. Easterly
low-level winds and favorable thermodynamics may support a few
supercells in this regime, but it appears likely that congealing
outflows will lead to multiple bowing line segments across the risk
area. Damaging winds and hail are the main threats, with isolated
tornadoes possible early in the convective evolution.
...West TX into eastern CO/western KS...
Mid level height falls are spreading into the central High Plains,
where strong heating and rapid destabilization is occurring. This
will lead to scattered thunderstorms throughout the region later
today. Deep boundary-layer mixing and steep low-level lapse rates
will promote strong outflows in the storms, with damaging winds and
hail being the main threats.
...FL and coastal GA/SC...
Relatively strong low-level winds are present today across most of
the FL peninsula, although veering/weakening is occurring across
southwest FL behind Alberto. Visible satellite shows broken clouds
across the region, providing some potential for daytime
heating/destabilization. This may lead to a few rotating cells
later this afternoon with a risk of isolated tornadoes. Based on
12z model solutions, am extending low tornado probabilities into
coastal sections of GA/SC for late tonight.
Visible satellite imagery shows a pocket of strong heating occurring
over parts of southern PA into northern VA. Meanwhile, a back-door
cold front is surging southward into the region. Given the
moist/unstable air mass in this region, have added a MRGL risk for
afternoon thunderstorms spreading east-southeastward as an weak
upper trough grazes the area. Locally gusty winds and hail are
possible with the strongest cells.
...Eastern Lower MI...
12z CAM solutions are consistent that a cluster of thunderstorms
will form this afternoon over southeast Lower MI ahead of a weak
shortwave trough and in region of strong heating. Forecast
soundings show considerable CAPE and sufficient vertical shear for
hail and gusty winds in the strongest cells.
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z