Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 190456

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1156 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 06z TAFs through 06z Wednesday Night)
Issued at 1144 PM CDT Tue Oct 18 2016

Cold front currently stretches from SW MO to just S of the STL
metro area into sthrn IL. A lone SHRA has been tracking E along
the bndry this evng. There could be addtnl isld activity overnight
with more scttrd precip dvlpng across sthrn MO towards 12Z. The
coverage is expected to increase thru the day as the bndry lifts
back north as an area of SFC low pressure moves to near the
Bootheel Wed night. Precip is fcst to move into the STL metro
area terminals by evng at the latest and that may be several hrs
too late. There is a window of opportunity for thunder Wed
aftn/evng with a better chance S of the STL metro area. Once the
precip should continue for most of the night. The
pattern suggests that MVFR CIGs may dvlp tomorrow night in and
near the precip. KCOU should be on the NW edge of the precip
while KUIN should be far enough N to stay dry.


VFR conditions expected thru 18Z. After that...scttrd convection
may impact the terminal with a more widespread rain mvng in for
the overnight hrs. There is some question as to exactly when
precip will begin. Once it is expected to last most of
the night. The pattern suggest that MVFR CIGs will be possible
tomorrow night as well. SFC low moves by drng the night dragging
the bndry back S in the process. Rain should come to an end around
12Z with clearing skies and a N wind the remainder of the day.





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