Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

058
FXUS63 KLSX 161931
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
231 PM CDT Mon Mar 16 2026

.KEY MESSAGES...

- Tonight will be the coldest night since the end of February with
  lows ranging from the single digits to mid teens.

- Light snow is likely Tuesday night, primarily across northeast
  Missouri into west central and south central Illinois.
  Accumulations are expected to be less than 1 inch.

- Temperatures warm significantly from Wednesday through the end
  of the week with highs expected to be well above normal.

&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 224 PM CDT Mon Mar 16 2026

Cold air continues to rush into the Mid Mississippi Valley on
northwest flow this afternoon.  Winds will gradually diminish
through the evening and overnight hours as low pressure moves
northeast from the Great Lakes through Quebec and a surface ridge
builds into the Midwest.  Lows tonight will likely be the coldest
since the February 22-23 time frame.  Single digit temperatures are
likely across northeast Missouri into west central Illinois with the
best radiational cooling conditions, especially where snow remains
on the ground. Low to mid teens are likely for the remainder of the
area where winds will remain stronger and some clouds may linger,
particularly across parts of south central Illinois.

The ridge axis moves moves east of the forecast area by early
Tuesday afternoon bringing southerly flow back to our area.  This
will begin the warm up for mid-late week.  Temperatures rise as much
as 30 degrees to the low to mid 40s in central Missouri where
southerly flow will begin as early as noon. A rebound of around 20
degrees into the low to mid 30s is in store for the rest of the area
by late Tuesday afternoon.

Attention turns to the only significant chance for precip in the
forecast for the next 7 days on Tuesday night.  A weak short wave
moves southeast across the Mississippi Valley.  Light precipitation
develops in the low level warm advection and moisture convergence
ahead of the wave spreading south east from Iowa across northeast
Missouri and much of Illinois.  Forecast soundings suggest the
precip should start out as all snow during the evening and gradually
transition to rain with perhaps a bit of sleet before ending
overnight.  Liquid equivalent is less than 0.10 inch across the
board, and in most of the area is less than 0.05, so snowfall
accumulations are expected to be less than 1 inch and mainly
confined to northeast Missouri and west central Illinois.  Soundings
show a layer of low level dry air farther south that should eat into
precip totals.  Additionally, temperatures will likely stay above
freezing across central, east central, and southeast Missouri into
parts of southwest Illinois, and even rise overnight due to the
strong warm advection.

Carney

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 224 PM CDT Mon Mar 16 2026

The mid-week warm up still looks on track as the long wave pattern
shifts east.  Temperatures Wednesday rise nearly 30 degrees over
Tuesday`s readings as low level flow shifts to the west in the wake
of the clipper. Continued westerly flow and rising heights aloft
lock the warmer temperatures in at least through Saturday.
Temperature IQRs through this period are mostly in the 4-6 degree
range on both the NBM and LREF, which is somewhat unusual with a
pattern shift of this magnitude.  However, this lends a good deal of
confidence to the forecast temperatures which rise from the low to
mid 60s on Wednesday up to the 70s on Thursday and mid 70s to around
80 on Friday.  The upper pattern becomes less amplified Saturday,
which lends to less predictability for temperatures.  Ensemble IQRs
open up to 10+ degrees for highs Saturday afternoon, though it looks
like a warm start to the morning in the 50s and with continued
westerly flow will enable temperatures to rise at least into the 70s
and possibly into the low to mid 80s across parts of central and
southeast Missouri.

The deterministic GFS and ECMWF show a short wave trough rippling
across the Upper Midwest and into the Great Lakes Region Saturday
night into Sunday.  The surface reflection of the wave pushes a cold
front through the Mid Mississippi Valley bringing temperatures back
down to near seasonal normals.  However, the timing on the frontal
passage is still very uncertain with some solutions pushing it
through early Sunday and others not until late Sunday afternoon or
Sunday night.  This is leading to a wide range in possible
temperatures for Sunday with both the LREF and NBM showing high
temperature IQRs of nearly 30 degrees.  Monday`s temperatures will
depend on how far the cold high pressure system behind the front
penetrates into the Midwest. Current indications are that it will
just sideswipe us here in the Mid Mississippi Valley.  However,
ensemble guidance continues to show a 10+ degree range of
temperatures between the 25th and 75th percentiles on Monday so
confidence remains relatively low.

Carney

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1234 PM CDT Mon Mar 16 2026

A broad area of MVFR ceilings will continue to prevail along and
east of the Mississippi River this afternoon. Occasional flurries
will also continue this afternoon, mainly with VFR visibility, but
some may be heavy enough to reduce the visibility to 3-5 miles.
Ceilings should lift and scatter gradually this evening, with VFR
conditions prevailing by 03-06Z. Otherwise, gusty northwest flow
will continue this afternoon and gradually diminish this evening
and overnight.

Carney

&&

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

$$

WFO LSX