Area Forecast Discussion
Issued by NWS St. Louis, MO

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851
FXUS63 KLSX 221222
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
622 AM CST Sun Jan 22 2017

.SHORT TERM...  (Through Late Tonight)
Issued at 351 AM CST Sun Jan 22 2017

Attention this prd will focus on storm system emerging from the
sthrn Plains. Closed low is expected to track from NE TX to wrn NC
while the assoc SFC low moves from NW AR to the sthrn Appalachians
from this mrng to Mon mrng. This set-up should spread decent precip
across the sthrn half of the FA but...the models have changed
significantly since 24 hrs ago. Now the precip shield is fcst to be
not nearly so robust. There should be two areas that have better
precip coverage. A SW-NE orientated frontogenetical band fcst to
dvlp over the next several hours across SE KS extending into NE MO.
This lift should persist most of the mrng with the band dssptng
around midday. Then another area of precip should lift N out of AR
thru the day as the lows pass just S of the CWA and then pivot
across the SErn FA drng the aftn. This solution means most of the
area largely misses out on the best precip chances. The threat of
rain diminishes from W-E drng the aftn with all but the far ern
zones expected to be dry by 00Z. PoP grids have correspondingly been
lowered. The highest PoPs this mrng are across cntrl and NE MO as
well as SE MO and then the focus on SE MO and sthrn IL for this
aftn. Winds should increase and become gusty thru the day as the
system passes E of the region. Gusty Nthrly winds should continue
overnight.

Despite the cloud cover and precip...temps should once again be well
above normal though not quite as warm as yesterday. Highs should
make it into the 50s with the exception of NE MO and W cntrl IL
where readings will hold in the mid/upper 40s...which is still 10-15
degrees above normal. Tonight will be cooler than the past two
nights but still above normal with lows in the 30s which is closer
to typical daytime highs for mid/late Jan.

Miller

.LONG TERM...  (Monday through Saturday)
Issued at 351 AM CST Sun Jan 22 2017

Breezy and cooler conditions will prevail on Monday morning, with
winds diminishing in the afternoon as the previous system continues
to advance well to the east and a weak surface high slides into the
area.  A deep long wave trof over the western U.S. will progress
eastward on Tuesday and Tuesday night with the lead upper low and
short wave trof moving out of the Rockies through the Plains and
into the mid/upper MS Valley by Wednesday morning. The accompanying
surface low and cold front will move across the CWA on Tuesday night,
but will be preceded by a strong WAA regime and moderating/above
average temperatures on Tuesday. Height falls aloft and weak large
scale ascent along and ahead of the advancing the cold front support
the potential for spotty/scattered showers across primarily northern
portions of the CWA.

A broad long wave trof will evolve during the later half of the week
over much of the CONUS with a series of disturbances impacting our
area within the increasingly cyclonic upper flow. The first of
these occurs in the Wednesday/Wednesday evening time frame, and
the ECMWF is a bit stronger and suggests enough forcing to
produce some light precipitation across the northern half of the
CWA. If this occurs it would largely be rain on Wednesday with a
potential for a rain/snow mix or some light snow on Wednesday
evening.

Temperatures will get back to near normal after Wednesday as the long
wave trof continues to evolve and the aforementioned disturbances
bring progressively colder air into the region.

Glass

&&

.AVIATION...  (For the 12z TAFs through 12z Monday Morning)
Issued at 540 AM CST Sun Jan 22 2017

Focus will be on the storm system passing S of the the area
today. This should spread precip N into at least SE MO and sthrn Il
later this mrng and into the aftn. S separate area of SHRAs will
continue across SE KS NE into NE MO thru the mrng. Precip is
expected to diminish from W-E thru the aftn with all the terminals
being dry by 00Z. A few spotty CIGs near 1000 feet. Thinking these
will be fairly short lived and should lift later this mrng. A more
uniform area of low end MVFR CIGs is fcst to build into the region
tonight. Winds are expected to increaser and become gusty later
this mrng as the low passes to the S

SPECIFICS FOR KSTL:

Scttrd CIGs near 1kft will impact the terminal this mrng. CIGs
should dsspt later this mrng with a more widespread area of MVFR
stratus fcst to move into the region tonight. Rain may move into
the terminal from the S later this mrng into this aftn...but this
solution remains very much in doubt. Winds will increase and
become gusty in the wake of the system this aftn and continue thru
the night.

Miller

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None. IL...None. &&

$$

WFO LSX



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