National Weather Service
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Severe Storm Outlook Narrative (AC)
acus02 kwns 240553
spc ac 240551
day 2 convective outlook
nws storm prediction center norman ok
1251 am cdt fri may 24 2013
valid 251200z - 261200z
... there is a slgt risk of svr tstms for a portion of ern mt / far
nern wy / wrn dakotas...
the upper air pattern will feature a wrn u. s. trough/cntrl u. s.
ridge/ern u. s. trough. downstream of the wrn states trough ... a
broad belt of moderate swly mid - level flow will overspread the nrn
high plains. a lee surface trough over much of the high plains will
serve as a focus for afternoon/evening storm development. farther
e ... a frontal zone will extend from the ern dakotas to the mid ms
valley to the west of surface high pressure centered over the great
... nrn high plains into the mid mo valley...
nwd moisture return into the cntrl - nrn plains on the backside of the
midwest surface high will be ongoing at the start of the day 2
period as a closed mid - level low remains centered over srn british
columbia. the lee trough located over cntrl mt will act to draw 50s
dewpoints westward into ern mt and upper 50s dewpoints invof the
black hills ... contributing to marginal - moderate instability. strong
diurnal heating will seemingly lead to isold to widely sctd storms
in the late afternoon - mid evening. deeply veering wind profiles
/40+ kt effective shear/ would support storm
organization ... including supercells with isold large hail/wind gusts
being the primary hazards.
farther se over the mid mo valley ... the terminus of a cntrl plains
30 kt llj will focus over the mid mo valley throughout the day.
although this region is beneath the upper ridge axis ... at least a
low risk for storms is supported by various operational models.
given moderate instability depicted by model forecast soundings ... a
conditional severe area has been included this forecast update.
... portion of the srn high plains...
a sely low level fetch of moisture located over the srn plains is
forecast to move westward into the srn high plains in concert with
the lee trough ... abutting next to the higher terrain in w tx and the
ern plains of nm. steep mid level lapse rates emanating from the w
and strong daytime heating will act to favor isold storm development
by afternoon ... initially favoring higher terrain. despite only 20
kt wly h5 flow ... strongly veering wind profiles would support some
storm organization featuring mainly higher - based multicellular
storms capable of perhaps a few severe wind gusts and marginally
severe hail. this activity should weaken during the evening hours
coincident with a stabilizing boundary layer..
.. smith.. 05/24/2013