Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

088
FXUS63 KLSX 161130
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
630 AM CDT Mon Mar 16 2026

.KEY MESSAGES...

- Accumulating snow comes to an end, while intermittent light snow
  showers/flurries remain possible east of the Mississippi River.

- Winds will continue to gust as high as 50 mph through mid-morning
  before weakening from late morning into the afternoon.

- Below normal temperatures persist through Tuesday before
  significant warming begins Wednesday with warming expected
  through at least Friday.


&&

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 155 AM CDT Mon Mar 16 2026

A strong system and associated cold front have shifted east of the
area this morning. Strong CAA, strong winds, and lingering light
snow showers/flurries are expected through the pre-dawn hours.
Sounding profiles from the deterministic RAP/NAM each show a mid-
level dry slot continuing to cut into the moisture across
southeastern sections of the CWA. Meanwhile, light snow hangs on
slightly longer over northeastern Missouri and west-central Illinois
as deeper saturation pivots through this region through early this
morning. Accumulating snowfall becomes less likely by 12z as the
trough axis shifts along/east of the Mississippi River and brings
with mid/upper ascent with it. All of this is accompanied by strong
winds that have been gusting into the 40-45 MPH range since late
last evening. Wind remain strong with a few gusts that could reach
or narrowly exceed 50 MPH. The wind advisory will remain as-is. This
combination will place wind chill values in -10F to 10F range around
sunrise before gradual improvement through mid-morning.

The rest of the day is characterized by winter-like cold. Gusty
winds and cloud cover add insult to injury as strong CAA persists
beneath low-to-mid level saturation. The deepest moisture lines up
east of the Mississippi River, where weak mid-level vorticity/omega
provide enough support for light snow/flurries on the cyclonic side
of the upper through. This potential peaks from mid-to-late morning,
generally along and east of I-55/north of I-70. Not much is expected
to come of this with increasingly limited moistures and gusty winds.
Both factors likely lead to a short duration of light snow with
fractured flakes, inhibiting much potential for accumulation.

Moisture profiles thin out westward through central Missouri this
afternoon, where clouds break through the later half of the day.
Unfortunately, for most locations, clouds will limit solar
insolation and even for those who see sunshine, heating will be
shunted by the strength of CAA and H8 temperatures generally ranging
from -10C to -15C. Considering the prognosis, temperatures will not
move much with highs in the 20s for most areas and a touch of
low/mid-30s over southeast Missouri.

Pressure gradient winds weaken significantly from west to east
between 15z through 21z, bringing an end the stronger gusts. Surface
ridging extends northward through the Mississippi Valley as high
pressure traverses the Gulf States from morning through early
afternoon Tuesday. There are two items to watch here as return flow
follows the ridge axis Tuesday afternoon, separating colder air to
the east from milder air to the west. A clipper system tracks
southeast through the region along the wing of WAA late Tuesday into
Tuesday night. It`s a quick hit of light precipitation with light
snow over the northeast sections of the CWA. Model soundings show
surface/mid-levels progressively drier over central, east-central,
southeast Missouri and southwest Illinois, where dry air is more
pronounced with dewpoint depressions of ~20 degrees. NBM suggests a
few tenths of an inch of snowfall could skim the northeast fringes
of the CWA Tuesday night with lows well below freezing (teens). This
lines up well with GFS/ECM ensembles which have shown good run-to-
run continuity in the multi-run 6-hourly QPF with as much as 0.05"
of QPF.


Maples

&&

.LONG TERM...  (Monday Night through Saturday)
Issued at 155 AM CDT Mon Mar 16 2026

Temperatures will make another dramatic swing through midweek as
WAA brings 50s/60s back to the mid-Mississippi Valley. One item that
causes me pause in the extent of 60s is the glancing reinforcement
of cooler air behind Tuesday night`s clipper system. This only seems
to briefly postponed the eastward advancement of warmer mid-level
temperatures. Nonetheless, highs will be 20+ degrees warmer than
Tuesday`s 30s/40s.

Thursday through Friday brings more promise with high confidence in
warmer-than-normal temperatures. Upper level height rises slowly
work in from the west as we get into the eastern fringes of the
western ridge. ECMWF ensembles show mean geopotential heights
exceeding the 90th percentile, which build east Thursday into
Friday. Another factor will be the surface to mid-level ridge over
the northern Gulf, along with its orientation and resulting
southwesterly flow over the central U.S. This setup is
climatologically favorable for strong WAA and sometimes over-
performing temperatures. There is some moisture return with
dewpoints climbing back into the 50s. That being said, moisture
isn`t overly abundant and could make for a more pleasant warmth
with temperatures well into the 60s/70s Thursday, possibly
approaching 80 degrees Friday northeast of the Ozark Plateau.

Saturday onward brings more questions than answers. While the ECMWF
ensembles show upper height rises reaching near the 95-99th
percentile, there are timing/placement differences with respect to
an approaching cold front and its associated low pressure that
traverses the northern CONUS. GFS deterministic may be a bit
bullish, but does show the potential for H8 temperatures to climb to
20-25C. Should this be the case, upper 70s/Low-80s wouldn`t be out
of the question. On the flip side, a quicker front will shunt
diurnal heating Saturday afternoon. NBM output suggests 70s will
stick through Sunday with a general downward trend in IQR values
late in the weekend.


Maples

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 626 AM CDT Mon Mar 16 2026

Impacts from a departing weather system will dwindle at all local
terminals through today. MVFR stratus is slowly making its way
eastward, clearing KCOU and KJEF this morning and then the
remaining local terminals this afternoon. Within the core of this
stratus is light snow, impacting KSUS, KSTL, KCPS, and
particularly KUIN. Given accumulation at KUIN and the strong
winds, some of the visibility reduction expected through this
morning is due to blowing snow. Winds will gradually decrease
through today, with gusts falling off after sunset with VFR flight
conditions expected tonight.

Elmore

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory until noon CDT today for Audrain MO-Boone MO-
     Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
     Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
     MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Francois MO-
     Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-
     Shelby MO-Warren MO-Washington MO.

     Winter Weather Advisory until 7 AM CDT this morning for Knox MO-
     Lewis MO-Marion MO-Monroe MO-Pike MO-Ralls MO-Shelby MO.

IL...Wind Advisory until noon CDT today for Adams IL-Bond IL-Brown IL-
     Calhoun IL-Clinton IL-Fayette IL-Greene IL-Jersey IL-
     Macoupin IL-Madison IL-Marion IL-Monroe IL-Montgomery IL-
     Pike IL-Randolph IL-Saint Clair IL-Washington IL.

     Winter Weather Advisory until 7 AM CDT this morning for Adams IL-
     Brown IL-Pike IL.

&&

$$

WFO LSX