Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

599
FXUS63 KLSX 141856
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
156 PM CDT Sat Mar 14 2026

.KEY MESSAGES...

- A strong cold front Sunday evening brings a threat for severe
  thunderstorms ahead of it and strong winds and light snow behind
  it.

- Temperatures behind this front are cold even by January
  standards, with a widespread freeze expected to last 36 to 48
  hours. Milder weather returns later next week.


&&

.SHORT TERM...  (Through Late Sunday Night)
Issued at 155 PM CDT Sat Mar 14 2026

We`re gradually establishing return flow today as low pressure is
strengthening in the lee of the Central Rockies in response to the
next potent trough moving through the Intermountain West. This
return flow accelerates tonight and by Sunday morning we`ll find
ourselves squarely in the warm sector of a developing strong cyclone
over the Plains tracking toward the Great Lakes. Temperatures warm
into the 60s, perhaps near 70, while dewpoints rise into the mid 50s
before a strong cold front pushes in from the west during the
afternoon to early evening. This potent system carries with it a
threat for severe thunderstorms, widespread strong wind gusts, and
snow.

As the system strengthens, wind flow through the warm sector
strengthens, creating a highly sheared environment. However,
instability remains lacking as dewpoints in the warm sector only
climb to the mid 50s. For comparison, the last severe weather
episode for this region featured dewpoints in the mid 60s. In
addition to weak instability, a strong cap exists across the warm
sector preventing access to that instability without strong forcing.
The forcing needed comes with the front itself, but most of the
convergence on the front is driven from the cold/dry side with the
front surging forward in the low levels to undercut the warm/moist
air. Thus the severe weather threat on Sunday is conditional upon
surface-based thunderstorms being able to develop, and that`s not a
guarantee. High resolution guidance indicates a thin convective line
along the front itself, with elevated showers immediately behind it.
The severe weather threat would be limited to that convective line.
With strong wind flow aloft, it is conceivable that the convection
could help push some strong wind gusts toward the ground, though
convective depth is pretty limited and it is unlikely that thin
updrafts will be able to establish strong downdrafts to enhance
this. Still, though, it is a highly sheared environment, and any
kinks in the line could pose a threat for brief tornadoes and
locally enhanced wind gusts. This threat increases to the southeast
where better instability is able to develop Sunday evening in the
lower Mississippi and Ohio Valleys.

While the severe weather threat is local and brief, the threat for
strong winds is widespread. Even in the warm sector ahead of the
front, strong flow aloft may allow for a few gusts near 45 mph.
However, the more widespread strong winds gusting to 50 mph or more
will be in the cold advection behind the front. This cold advection
promotes subsidence which allows for superb mixing of strong gusts
down to the surface. These cold advection winds will be strongest
closer to the surface low which is tracking through Iowa into
northern Illinois. There remains some low potential (30 percent or
less) for gusts to 58mph or more (High Wind Warning) in our far
northern forecast area. Confidence in this remains too low for an
upgrade to a High Wind Warning, but we are very confident it will be
windy.

A sharp temperature drop accompanies the cold front. Temperatures
drop 20 degrees in just a few minutes, with a continued downward
trend as cold advection continues through the night. Precipitation
along and behind the front stays in the form of rain and likely ends
before the temperature falls below freezing. However, the deep
cyclone tracking to our north produces an area of wrap around
snowfall that may extend from eastern Iowa southwest into northeast
Missouri. Latest trends in guidance show greater uncertainty on
whether this snow band will extend into our forecast area or remain
to the north, but confidence is greatest in impacts from this in
northeast Missouri toward the Quincy area in Illinois. This band is
likely to produce an area of 1 to 3 inches of snow with the
difference between the low end and the high end hinging on how long
the band lingers. If it tracks mainly off to the northeast along its
axis, then a narrow band of amounts closer to 3 or even 4 inches are
possible. But if it pivots to the east as it exits then more
widespread lighter amounts can be expected. Snowfall amounts with
this forecast were heavily coordinated with neighboring offices as
NBM forecast amounts were significantly higher than other guidance
sources, likely having trouble resolving the difference between the
frontal precip and the wrap around band.

Kimble

&&

.LONG TERM...  (Monday through Next Saturday)
Issued at 155 PM CDT Sat Mar 14 2026

Monday is going to be cold. Even by mid-winter standards it will be
cold. Most areas stay below freezing despite some late day sun. With
the surface high moving in overnight, Monday night will be the
coldest night, though we may not see the full potential of this air
mass as the surface high is coming into the area late in the night.
If we see a longer period of clear, calm conditions then we should
expect more widespread temperatures approaching the dewpoint, in the
mid single digits. But some lingering winds in the evening may
prevent that stronger cooling, leading to more widespread teens.

From Tuesday onward we see a warming trend as ridging over the
western US gradually expands eastward. One blip in this warm up
comes from a quick moving wave tracking southeast through the
northwest upper level flow Tuesday night. Warm advection style
precipitation falls along and ahead of the wave`s track, but at that
point it`s still cold enough for snow. The focus of this
precipitation is primarily from eastern Iowa into northern and
central Illinois, but some adjustments in this track could shift
this area of impact a bit further southwest into our area. At the
moment we have some low chances for light snow in the forecast based
on that track uncertainty. If light snow does fall, it will be brief
and not last long. A rapid warm up on Wednesday (into the 60s) will
make it hard to notice it happened if you aren`t up early enough in
the morning to see it. The rest of the week continues the warm up to
more spring-like warmth in the 70s and potentially 80s.

Kimble

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1229 PM CDT Sat Mar 14 2026

VFR conditions continue today, with a southeast wind turning
southerly and increasing by morning. Gusty winds are expected
through the day on Sunday with some potential for developing MVFR
ceilings as well. A strong cold front moves through from west to
east Sunday evening, shifting winds to the west with strong gusts
likely. MVFR ceilings are more likely behind the front for a
period of time. A round of thunderstorms is possible along the
front, with a brief period of showers behind it.

Kimble

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory from 10 AM Sunday to noon CDT Monday 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.

IL...Wind Advisory from 10 AM Sunday to noon CDT Monday 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.

&&

$$

WFO LSX