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.
Bismarck, ND...Mandan, ND...Dickinson, ND...Miles City, MT...Glendive, MT...
Des Moines, IA...Billings, MT...West Des Moines, IA...Minot, ND...Ankeny, IA...
Omaha, NE...St. Louis, MO...Huntsville, AL...Sioux Falls, SD...Cedar Rapids, IA...
SPC AC 281616
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1116 AM CDT Thu Jun 28 2018
Valid 281630Z - 291200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
EASTERN MONTANA...MUCH OF NORTH DAKOTA...AND NORTHWEST SOUTH
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE
NORTHERN PLAINS...AND OVER PARTS OF THE TENNESSEE VALLEY AND
Severe thunderstorms are likely across the northern Plains,
especially this afternoon and tonight, with the potential for very
large hail, widespread damaging winds, and a few tornadoes. Other
severe storms can be expected across the middle to lower Missouri
Valley and the Southeast States.
Isolated severe thunderstorms have been ongoing this morning in area
of low-level warm advection over ND and MN. Locally intense storms
will remain possible through the afternoon in this regime, with
large hail and damaging winds possible.
By mid/late afternoon, the influence of a strong upper trough in the
western states will begin to affect western/central MT. Favorable
heating, dewpoints in the 50s, and strong winds aloft will promote a
few severe storms capable of hail and wind. As this activity
spreads eastward, more robust convection should develop in the
eastern plains of MT, with supercells and very large hail possible.
A few tornadoes may also occur in this region before storms
merge/congeal into multiple bowing line segments. Damaging wind
threat will likely become rather widespread across parts of ND after
Several 12z model runs suggest a risk of a linear MCS tracking into
parts of MN/WI overnight. Have expanded the MRGL risk to account
for this potential.
...TN Valley into Southeast states...
A band of strong thunderstorms extends from western KY, across
middle TN, into northern GA. These storms are expected to build
southward through the day, into a very moist and unstable air mass.
Winds aloft are just strong enough for a few multicell clusters
posing a risk of organized damaging wind potential. Southward
extent of storms will be modulated by mesoscale organization, but
may reach into north FL before weakening.
A moist boundary layer is present today over parts of NY/NJ and
southern New England, with dewpoints in the 70s. Scattered
thunderstorms are expected to form this afternoon and spread across
the MRGL risk area. Thermodynamic parameters are weak, but low/mid
level winds are sufficiently strong for a few wind gusts in the most
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