Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 182355

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
655 PM CDT TUE OCT 18 2016

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 332 PM CDT Tue Oct 18 2016

The cdfnt continues to push SE thru the region this afternoon.
Behind the fnt, cooler and drier air will filter into the area. This
fnt will stall just south of the CWA tonight with a sfc wave
developing along the fnt. There is already some indication of this
development within the sfc fields across far srn OK and nrn TX
region. Mdls show good moisture convergence along and near the 850mb
fnt ahead of the developing sfc low. However, there are differences
in placement of the best forcing as well as timing.

Have kept low PoPs across srn portions of the CWA with a low chance
for precip, but not zero. These chances are expected to spread back
north late tonight, but are expected to be focused across srn
portions of the CWA thru Wed morning.

Mdl guidance suggests this fnt will lift north slightly, back into
srn portions of the CWA as the sfc wave and corresponding upper trof
approaches the area. This will present a conditional threat for
severe storms, mainly during the afternoon hours across far srn
counties. However, TSRA are possible further north and west with
decreasing chances for TS further NW.


.LONG TERM...  (Wednesday Night through Next Tuesday)
Issued at 332 PM CDT Tue Oct 18 2016

Stationary front remains draped over southern IL and MO Wed night
ahead of surface wave. Precip chances are highest Wed night into
Thurs as low level moisture and low to mid level instability
remain favorable and deepening upper level trough pushes a surface
wave along stationary front. Precip will be concentrated along and
to the north of the front. With the passage of the sfc wave and
trough Thurs expect flow to shift to northerly bringing temps down
from the record highs of earlier this week to more seasonable
values between 60 and 70 through Sat. Upper level ridge moving
into the plains begins to bring temps up late weekend into next
week. The remainder of the period remains dry after Thurs.



.AVIATION...  (For the 00z TAFs through 00z Wednesday Evening)
Issued at 637 PM CDT Tue Oct 18 2016

Cold front aligned along I44 in MO and I70 in IL as of 2330Z. This
bndry will continue to slowly sag S this evng but is expected to
stall overnight along the AR/MO border as a wave of low pressure
forms farther SW along the front across ern OK. The area of low
pressure is fcst to ride NE along the bndry Wed and Wed night
which will cause the front to move back north some tomorrow.
Scttrd precip is expected to dvlp across sthrn MO after midnight
as a weak LLJ rides over top of the SFC bndry. I expect most of
this activity to remain well S of the MO Rvr drng the mrng. But as
the front buckles N in advance of the the SFC low and upper level
support...expect widespread precip to dvlp drng the aftn across
sthrn MO and move into the STL metro area terminals no later than
the evng...though could be several hrs sooner. There is enough
elevated instability for there to be a few rumbles of thunder
mainly drng the aftn/evng. Once the precip begins it should
continue most of the night. KCOU appears to be on the NW fringe of
the precip tomorrow and KUIN should be too far N and is expected
to remain dry.


VFR and dry tonight with rain dvlpng tomorrow aftn/evng. Scttrd
SHRAs dvlp Wed mrng S of the terminal and then become more
widespread drng the aftn with a rumble of thunder possible. Rain
should move into the terminal by evng...if not sooner...and is
expected to last the rest of the night. The setup Wed night is
favorable for low CIGs and fog but did not get too carried
away...but would be surprised for both CIGs and VSBYs to drop to
MVFR tomorrow night.





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