- Day Three
acus03 kwns 170711
Storm Prediction Center ac 170710
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0210 am CDT Tue Jul 17 2018
Valid 191200z - 201200z
..there is a marginal risk of severe thunderstorms across parts of
the middle Missouri and upper Mississippi valleys...
A marginal severe threat will be possible on Thursday across parts
of the mid Missouri Valley into the upper Mississippi Valley.
..mid Missouri Valley/upper Mississippi Valley...
A shortwave trough is forecast to move eastward into the upper
Mississippi Valley on Thursday as a cold front advances
southeastward across the northern plains. The models are forecasting
a moist airmass to be in place across the mid Missouri and upper
Mississippi Valley where surface dewpoints should be upper 60s to
lower 70s f. As a result, moderate instability appears likely to
develop across much of the moist sector by Thursday afternoon. Model
forecasts are not in agreement on where convective development will
be most probable. The NAM is forecasting late afternoon storms in
western Minnesota while the GFS and European model (ecmwf) show storms in southern
Minnesota and east-central Iowa. This outlook favors the GFS and
European model (ecmwf) solutions which suggest an isolated severe threat will be
possible in western portions of the upper Mississippi Valley. A
marginal risk area has been added from near the Mississippi River in
northeast Iowa westward into southeastern South Dakota and northeast
Nebraska where storm coverage may be isolated but strong instability
is forecast. Marginally severe wind gusts and hail will be possible
with the cells that develop in areas with the strongest instability.