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acus03 kwns 240732
swody3
Storm Prediction Center ac 240730
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0230 am CDT Friday may 24 2013
Valid 261200z - 271200z
..there is a slight risk of severe thunderstorms for parts of northestern Wyoming / western South Dakota /
western Nebraska...
...
The upper pattern for the day 3 period is characterized by a western
U.S. Upper trough centered over the Pacific northwest...a middle level ridge
over the central u... a slow-to-depart closed low over New
England. Models hint at a lead disturbance moving into the Central
High plains by Sunday evening as a weak Central High plains low
becomes established with an attendant Lee surface trough/dryline.
..cntrl and northern plains...
Early day storms --perhaps ongoing at the start of the period-- may
occur in vicinity of a residual northwest-southeast oriented frontal zone over the middle MO
valley region. Forecast soundings show only marginal instability
and modest deep flow and would suggest these storms may be
sub-severe. Attention focuses westward over the northern-Central High plains
later in the day as strong heating is forecast to occur on the western
edge of moisture located over the central-northern High Plains. A Stout
eml featuring 12-14 degree c 700 mb temperatures from the Texas Panhandle northward through
western Kansas will likely limit storm coverage from western Kansas southward into western Texas
on the dryline. Weak height falls by evening over the Central High
plains in association with an ejecting impulse and generally
lowering heights over the northern plains in advance of a northern Great Basin
speed maxima...would in turn become more favorable for storm
development.
Forecast soundings from parts of western Kansas towards the Black Hills show
a very steep lapse rate environment with SBCAPE ranging from
1500-2500 j/kg expected near and east of the dryline/Lee trough. Deep
layer shear will likely remain modest /25-35 knots effective shear/
over the region. Strong heating will act in concert to weaken and
locally erode the cap with isolated storm coverage expected. The low level jet
is forecast to strengthen during the evening into the
overnight...potentially allowing some of the evening storms to
linger into the overnight.
..wrn Kansas southward into western Texas...
A few diurnally-driven storms may form by the late afternoon/early
evening hours within a deeply mixed boundary layer. Shear profiles
will support some storm organization in the form of multicells and
perhaps transient supercell structures. Isolated damaging winds and large
hail may occur with the strongest storms.
.Smith.. 05/24/2013
