U.S. Severe Weather Forecast for Day 3

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acus03 kwns 250731 
swody3 
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. 


.Smith.. 05/25/2013