- Day Three
acus03 kwns 190718
Storm Prediction Center ac 190717
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0217 am CDT Tue Sep 19 2017
Valid 211200z - 221200z
..there is a marginal risk of severe thunderstorms across eastern
North Dakota and northern/central portions of Minnesota...
A few hail-producing storms are possible in portions of Minnesota
and eastern North Dakota Thursday night.
An amplifying longwave trough across the west will become nearly
stationary with time, while a mid/upper ridge becomes established
across the Great Lakes and Ohio Valley. At the surface,
cyclogenesis will begin in earnest across the northern plains as a
ridge becomes dominant across the northeast and Appalachians.
Southerly low-level flow across much of the center of the country
will result in a moist low-level airmass retreating northward, with
60s f dewpoints reaching the Minnesota/Ontario border overnight.
..eastern North Dakota and northern/central Minnesota...
The amplification of the long-wave trough in the west will result in
backing mid/upper flow and subtle height rises during the day, which
should keep daytime convective potential at a minimum. In the
evening, however, strengthening low-level flow will occur in
conjunction with a 50-55kt 850mb jet across the Central Plains, and
convergence on the nose of this synoptic-scale feature will Foster
scattered thunderstorm development primarily after 00z. Steep
mid-level lapse rates and kinematic profiles will result in
primarily a hail threat with elevated convection occurring across
the region. Marginal (5%) severe probabilities have been added to
address this threat, and later outlooks may needed higher
probabilities if more focused corridors of hail potential become