U.S. Severe Weather Forecast for Day 3
Upcoming severe weather outlook.
acus03 kwns 250731
Storm Prediction Center ac 250730
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0230 am CDT Sat may 25 2013
Valid 271200z - 281200z
..there is a slight risk of severe thunderstorms across a portion of the northern
plains...middle MO River Valley...and southern High Plains...
A shortwave trough will move from the northern Great Basin/northern
intermountain region through the northern High Plains and into S-central
Canada by Tuesday morning. As this occurs...a larger-scale upper
trough over the western U.S. Will reinvigorate/amplify in response to a
powerful east Pacific jet streak moving into California late in the period.
Stronger southwesterly flow aloft on the nose of the southern branch of the westerly/S
is forecast to overspread a large part of the plains with a few low
amplitude speed maxima potentially influencing storm development
over the central states.
..mid MO River Valley into the northern High Plains...
Moist southerly low level flow emanating from the central-Southern Plains and
evapotranspiration effects will lead to A Reservoir of 60s dewpoints
extending from the Southern Plains into the north-Central Plains Monday
afternoon. An eml and warm 700 mb temperatures will overspread much of the
plains acting to delay/confine storm development through much of the
day with the possible exception for morning storms over the middle MO
River Valley eastward into the middle MS River Valley region. The European model (ecmwf)
depicts a shortwave disturbance moving across the Central Plains
during peak heating with trailing influence perhaps as far S as the
Texas Panhandle...in addition to the northern stream shortwave moving across
eastern Montana/western Dakotas during the day. These two features will likely
prove instrumental in providing weak large scale support for storms
Monday afternoon through the evening. Models show slightly stronger
middle-level southwesterly flow than prior days over this region /30-40 knots
effective shear/. Forecast soundings by afternoon become quite
unstable across the Central Plains featuring 2500-3500 j/kg MLCAPE and
1000-2000 j/kg MLCAPE farther north over portions of the northern High
Plains/western Dakotas. Despite modest deep layer shear...the magnitude
of potential instability would yield the possibility for supercells
and organized line/bowing segments capable of mainly isolated large
hail/severe wind gusts and perhaps a few tornadoes. A strengthening
low level jet during the evening over the Central Plains would be supportive of
upscale growth into a few clusters of storms with this activity
possibly moving into the middle MO River Valley late.
..W-central Kansas southwestward into West Texas...
A west-east oscillating dryline over the central-Southern Plains will
likely serve as a focus for at least isolated diurnally-driven storms
once again on Monday. Isolated storm development will preferentially
favor where heating and where low level convergence are maximized.
Although storm coverage will likely remain limited from Kansas southward...the
stronger updrafts would have an attendant large hail/severe wind
gust threat before this activity weakens during the evening.