U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 270525 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1225 am CDT Wednesday Aug 27 2014 

Valid 271200z - 281200z 

..there is a slight risk of severe thunderstorms from western Kansas into southern Nebraska... 

scattered severe storms with hail and wind are expected this 
afternoon from western Kansas into southern Nebraska. Isolated wind 
and hail will also be possible over much of Missouri eastward across 
the Ohio River valley...with locally strong wind gusts over the 
northeastern states. 

An upper low will move slowly eastward from Utah into Colorado...with enhanced 
southwesterly flow aloft across the Central Plains. At the surface...a low 
pressure trough will exist across eastern Colorado/western Kansas...with a front along 
the Nebraska/Kansas border. A warm and moist air mass will remain from MO 
into the Ohio Valley and will fuel isolated daytime storms beneath the 
upper ridge. To the east...an upper trough will arrive across the northestern 
state by late in the day with a surface trough focusing a few strong 
storms from PA into southern New England. 

..wrn Kansas into southern Nebraska... 
A leading disturbance ahead of the main upper low is forecast to 
affect the Central High plains during the day with weak low pressure 
over eastern Colorado and a front across southern Nebraska. Although the early shortwave 
trough passage and minimal cin will lead to rain and storms early 
the day...heating in the wake of the early activity should lead to 
stronger activity by late afternoon from near the Colorado/Kansas border northeastward 
across western Kansas and into southern Nebraska. Veering winds with height and 
sufficient instability will favor a few supercells capable of large 
hail and a few severe wind gusts. Lower T/dew point spreads across northern 
Kansas/southern Nebraska and locally backed surface flow may result in a brief 
tornado threat as well. 

..MO eastward across the Ohio Valley... 
An axis of moderate instability will stretch from MO eastward across the 
Ohio Valley but with weak winds aloft under the upper ridge. The 
presence of strong heating and ample low-level moisture will lead to 
isolated storms...a few of which may produce localized severe wind 
and hail. 

..ern PA into southern New England... 
A weak surface trough/front will provide a focus for thunderstorms 
as a low amplitude upper trough arrives late. This will allow for 
strong heating and destabilization with MUCAPE on the order of 
1000-1500 j/kg in a narrow zone. Low to midlevel wind fields will 
not be particularly strong...but sufficient shear will exist for a 
few cells capable of small hail and locally damaging wind gusts. 
Activity should wane quickly by early evening with loss of heating. 

.Jewell/Mosier.. 08/27/2014 

Mesoscale Discussion

acus11 kwns 262012 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 262012 

Mesoscale discussion 1624 
National Weather Service Storm Prediction Center Norman OK 
0312 PM CDT Tuesday Aug 26 2014 

Areas affected...northeast/east-central Colorado and southeast Wyoming to 
western Nebraska/northwest Kansas 

Concerning...severe potential...watch unlikely 

Valid 262012z - 262215z 

Probability of watch issuance...20 percent 

Summary...isolated instances of severe hail/locally damaging winds 
will be possible by late afternoon/early evening across portions of 
northeast/east-central Colorado and southeast Wyoming to western Nebraska/northwest 

Discussion...thunderstorms /some strong/ continue to increase 
particularly over the Colorado foothills as of 20z...and to a lesser 
extent over western Colorado/far southeast Wyoming. While some inhibition in 
the boundary layer seemingly exists in the short-term across the 
plains...storms should develop/spread eastward across the Central 
High plains through the late afternoon/early evening hours as 
additional destabilization occurs /up to 1000-1500 j per kg MLCAPE/. 
Aided by weak Lee-side surface low development...the scenario will 
be influenced by modest low-level upslope/moistening and a possibly 
a weak embedded shortwave trough amid southwesterly flow aloft. With 
regional WSR-88D vwp data only currently indicative of 25-35 knots of 
deep-layer shear...relatively modest forcing/vertical shear regime 
should limit the overall organization/extensiveness of the severe 
risk. Nevertheless...some of the stronger multicellular development 
may pose a risk for severe hail and/or locally damaging 
winds...initially across the Colorado Front Range vicinity...and 
subsequently into the High Plains through the late afternoon/evening 

.Guyer/Mead.. 08/26/2014 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 41990508 42840369 42270226 41190145 39340182 38980377 
39760514 41990508