National Weather Service
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Severe Storm Outlook Narrative (AC)
acus02 kwns 181710
spc ac 181709
day 2 convective outlook
nws storm prediction center norman ok
1209 pm cdt sat may 18 2013
valid 191200z - 201200z
... there is a mdt risk of svr tstms across parts of ks/ok/wrn mo...
... there is a slgt risk of svr tstms surrounding the mdt risk from
ncntrl tx into srn mn...
... regional severe weather outbreak possible across parts of the srn
plains ... cntrl plains and lower mo valley...
... srn plains to lower mo valley....
latest model guidance continues to suggest a significant mid level
speed max will evolve within the base of the wrn u. s. trough over
the srn rockies late day1 ... then eject across the srn plains toward
wrn mo by 20/00z. there are minor differences among the 12z nam/gfs
and 00z ecmwf ... with the nam favoring a bit more aggressive speed
max/height falls across nern ok into swrn mo than the other
guidance. it/s not entirely clear if the more displaced nam speed
max is correct ... if so then significant severe tstm activity could
spread east of depicted mdt risk.
for now will opt for somewhat slower gfs solution as it has been
very consistent regarding the forecast height field/wind speeds
across the srn plains into wrn mo. given this solution ... at sunrise
it appears synoptic front will extend from a sfc low over ncntrl
neb ... swd across cntrl ks into the tx panhandle. a dryline is
expected to intersect the cold front over swrn ks ... extending sswwd
into nwrn tx. early morning convection will likely be confined to
warm advection zone along the nose of the llj across the cntrl
plains into the mid ms valley. south of this activity strong warm
sector boundary layer heating is expected during the
day ... especially south of i - 70 corridor across ks/ok/tx.
combination of strong heating and strengthening wly flow aloft will
allow dryline to mix to a position from cntrl ks ... sswwd across swrn
ok into nwrn tx by 21z. if however the nam solution is correct then
the dryline may mix to the i - 35 corridor by late afternoon.
given the expected intense heating along the dryline there is ample
reason to believe discrete supercell structures will evolve
initially north of the mid level jet core across ks ... then swd into
ok. this may occur by 21z over ks and by 20/00z across ok to near
the red river. forecast shear profiles strongly favor long - lived
supercells and where dew points hold in the upper 60s/lower
70s ... tornadoes can be expected. given the expected
shear/instability there is support for strong tornadoes.
additionally ... very large hail should accompany this activity.
maturing complex of storms should progress across ks/nern ok into
wrn mo with more scattered activity across cntrl/srn ok.
... sern u. s...
remnant mid level short - wave trough will shift across the srn
appalachians sunday. this feature may once again serve to focus a
few strong thunderstorms beneath a weakening mid level wind field.
gusty winds or perhaps some hail could be noted with diurnally
.. darrow.. 05/18/2013