Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 262010

Area Forecast Discussion
National Weather Service Saint Louis MO
310 PM CDT FRI AUG 26 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 307 PM CDT Fri Aug 26 2016

The synoptic pattern early this afternoon features a broad
subtropical ridge across the southeastern CONUS with a trough
digging into the northwestern CONUS.  This has placed Missouri and
western IL within broad southwest flow aloft, a regime which will
persist through tonight.

Convection has developed over the last couple of hours across
portions of western IL.  This region received some sunshine earlier
today and has become rather unstable with MLCAPEs around 2500 J/kg.
The better deep layer shear is displaced north of this region, but 0-
6km shear values around 30 knots may be enough for some loose
organization to the multicells as they continue to develop.  Main
threat will be locally strong winds, but the backbuilding nature of
some of the convection in the high PWAT airmass (around 2 inches)
will also lead to some localized flash flooding concerns as well.

Further west across central and east-central MO, expansive low/mid
cloud cover has kept the region more stable.  Therefore, surface-
based convection will be limited in this region with only a few
showers or an isolated storm through the early evening.  Attention
will then turn to the west where convection is expected to develop
near the Kansas City area and spread ENE through the late evening
hours. This activity may attempt to grow upscale into a small MCS
which will likely clip portions of northern MO and west-central IL
(near the Quincy area).  Given the timing, do not expect this
activity to be severe once it reaches the LSX CWA, but a few strong
storms will be possible especially across northern MO.


.LONG TERM...  (Saturday through Next Friday)
Issued at 307 PM CDT Fri Aug 26 2016

Complex that develops over northwestern Missouri tonight to slide
east and diminish Saturday morning. Otherwise, active pattern to
continue through rest of forecast period with weak surface ridge
staying put over region. Will see chance of storms each day as
upper level shortwaves undercut surface ridge. Best chances will
be during peak heating, i.e. afternoon/evening hours.

Highs will be in the 80s Saturday through next Friday, with lows in
the upper 60s to low 70s.


.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1224 PM CDT Fri Aug 26 2016

Challenging TAF forecast as low cigs and convection are all in the
cards. IFR to even LIFR cigs at times continue to persist north of
a warm front at COU and UIN early this afternoon. Expect these low
cigs to continue for the next couple of hours before slowly
improving through this afternoon. The low clouds and another mid-
level deck has kept the region fairly stable early this afternoon.
Still think we could see a few showers/storms develop late this
afternoon into early this evening especially at STL/CPS/SUS where
instability is a bit higher.

Mid-level cloud cover will continue to stream by through the
afternoon and evening hours which will overall limit instability.
May be enough breaks to spark a few showers/storms, thus will
continue with VCTS mention late this afternoon/early evening, but
that may even be overkill at this point. Light and variable winds
this afternoon will turn more to the SSE this evening and into


Saint Louis     75  88  73  89 /  30  30  30  30
Quincy          70  85  70  86 /  50  50  30  30
Columbia        69  85  70  87 /  20  30  30  30
Jefferson City  70  87  70  88 /  20  30  20  30
Salem           73  87  71  88 /  40  40  20  30
Farmington      71  86  70  88 /  30  30  20  30



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