- Day Three
acus02 kwns 241717
Storm Prediction Center ac 241717
Day 2 convective outlook
National Weather Service Storm Prediction Center Norman OK
1217 PM CDT sun Jun 24 2018
Valid 251200z - 261200z
..there is a slight risk of severe thunderstorms for
Iowa...northern Missouri...and western Illinois...
A few severe thunderstorms are possible across Iowa, northern
Missouri and western Illinois on Monday.
A mid-level shortwave trough over the north-Central High plains
midday Sunday will evolve into a closed low and migrate east through
the middle MO valley and into the upper Midwest by daybreak Tuesday.
A belt of strong mid-level flow will move through the base of the
trough over the lower MO valley. An occluded surface low is
forecast over eastern NE with a warm frontal zone draped east into
the middle MS valley. A myriad of convective outflow will serve as
an effective front over eastern KS/OK.
Farther west, a disturbance will move into the northern rockies with
attendant mid-level height falls overspreading the northern High
Plains primarily from Monday evening into the overnight.
---A low-confidence/highly conditional forecast remains unchanged
from the previous outlook.--- Scattered storms are likely to be
ongoing throughout the day along the advancing warm front, from MO
into Iowa and Illinois. While this may reduce instability, the air mass
will be very moist, and low-level shear will be enhanced along the
warm front. If instability develops similar to some model
depictions, the threat for a few supercells may materialize.
However, this potential outcome is highly conditional and is
somewhat dependent on the evolution of convective outflow prior to
the day2 period and the quality of moisture/destabilization along
the boundary Monday afternoon. Other thunderstorms are possible by
afternoon ahead of the weak low, from near the NE/Iowa border across
Iowa. Marginal hail and locally damaging wind will be possible as
well. The potential for widespread precipitation does decrease
predictability for this scenario, and areal adjustments in future
outlooks are possible.
..lower Ohio Valley into the Carolinas...
Models indicate ongoing storms Monday morning across Kentucky and Tennessee as
westerly 850 mb winds maintain moist/warm advection. This activity
may persist or regenerate later in the day downstream toward the
Carolinas, tracking along the front. Locally damaging wind or hail
will be possible.
One forecast scenario, partially depicted in model guidance,
involves an mesoscale convective vortex over the Ozarks midday Sunday moving east into NC by
mid afternoon Monday. Enhanced flow in the mid levels associated
with this feature may augment the risk for severe thunderstorms in
the form of damaging gusts. If this possibility becomes increasing
probable, higher severe probabilities may be introduced in later
..maximum risk by hazard...
Tornado: 5% - slight
wind: 15% - slight
hail: 5% - marginal