Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

799
FXUS63 KLSX 020400
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1100 PM CDT Wed Apr 1 2026

.UPDATE...
Issued at 743 PM CDT Wed Apr 1 2026

Have issued a Flood Watch through 1 pm tomorrow for central and
northeast Missouri. Showers and thunderstorms are starting to
expand in areal extent across central and southwest Missouri into
southeast Kansas along stationary front. This trend is expected to
continue through the rest of the evening into the overnight hours
and spread across the watch area as the low level jet strengthens
ahead of mid level trough moving east across the Plains. The HREF
is showing PWATS near 1.5" which is near max climo for early April
with 24 hour LPMM values ranging from 1.5 to 4+ inches in the
same areas that saw heavy rain earlier today. RAP soundings are
also showing modest warm clouds depths indicating a watch is
needed through midday tomorrow.

Britt

&&

.KEY MESSAGES...

- Showers and thunderstorms are expected tonight into tomorrow
  morning, where a narrow swath of heavier rain (2"+) may lead to
  some localized flooding across central Missouri. Small hail and
  damaging winds are possible.

- Additional showers and thunderstorms are possible tomorrow
  afternoon and early evening, with the greatest threat for severe
  thunderstorms across northeast Missouri and west-central
  Illinois.

- A cold front will pass early on Saturday, resulting in dry
  weather and cooler conditions.


&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 329 PM CDT Wed Apr 1 2026

A broad area of showers and elevated thunderstorms across central
and east-central Missouri from earlier this morning helped to push
the cold front further south than previously forecasted. Now the
quasi-stationary cold front stretches from Rolla MO to near
Farmington MO and eastward towards Carbondale IL. This front has
been the dividing line between temperatures in the upper 40s/lower
50s with thick stratus to the north while 70s are being observed to
the south.

Currently, within the open warm sector across southern Missouri,
surface based instability has increased with 1,500-2,000 J/kg and
modest 0-6km bulk shear values around 30-40kts aiding in convective
initiation. High-res guidance resolves these storms moving
northeastward and expanding in coverage across central and possibly
east-central Missouri around around 00Z this evening. A majority of
these thunderstorms will outrun the warm front as they move
northeastward into a capped environment becoming elevated, limiting
the severe threat to generally small hail only. However, any
thunderstorms this afternoon and evening that remain along and south
of the warm front, in the open warm sector generally across the
southern half of Missouri, would be capable of producing severe
hail, damaging winds, and isolated tornadoes.

Another threat that may develop later this evening into the
overnight period is localized heavy rain as anomalous moisture, with
PWATs of 1.3-1.5" (near 99th percentile), interacts with the warm
front. This threat is highly conditional on the northward
progression of the warm front, with a slower northward progression
leading to increased potential for training thunderstorms resulting
in localized flooding. Over the past 12-16 hours, the heaviest rain
has fallen near central Missouri and points east-northeastward where
pockets of 2"+ have been observed. Current indications are that the
corridor of heaviest rain this evening and overnight will be across
central and northern Missouri with a broad swath of 1-2" expected
along with the HREF LPMM indicating localized pockets of 2-4" are
possible. Therefore, locations across central Missouri will be more
susceptible to nuisance flooding overnight if localized heavy
rainfall occurs in that area.

At 500mb, a mid-level trough is digging into the Intermountain West
and is progged to eject into the Central Plains overnight. Lee side
surface cyclogenesis is already in motion across the High Plains
which has started to influence our quasi-stationary cold front by
slowly lifting it to the north as a warm front. Recent trends
indicate a slightly quicker northward progression of the front this
evening with general consensus on the front reaching the I-70
corridor around 06Z tonight and northern Missouri by sunrise on
Thursday. Temperatures south of the warm front will rebound into the
60s leading to warmer temperatures overnight than highs today for
most locations.

On Thursday, the surface cyclone will be traversing northeastward
across Iowa, placing our region in the open warm sector. Model
guidance varies significantly on the departure of morning convection
and how much our environment destabilizes by the afternoon ahead of
the northwestward approaching cold front. Joint probabilities for
MUCAPE >500 J/kg and 0-6km Bulk Shear >30kts on the REFS max out
around 50% across east-central and northern Missouri tomorrow
evening. The timing of the cold front along with the mid-level
trough and greatest forcing will be key for our severe weather
threat, with potential for the cold front to be behind the greatest
mid-level forcing. If that is realized, then the severe threat would
be lower. Currently, guidance indicates that the cold front will
enter northern Missouri tomorrow evening and struggle to make it
south of I-70. As a result, the severe weather threat for Thursday
is along and north of I-70 with the greatest threat across northeast
Missouri and west-central Illinois. Forecast model soundings for
that area indicate surface based convection is possible along and
ahead of the cold front with large hail, damaging winds, and
tornadoes all possible.

Peine/Delia

&&

.LONG TERM...  (Friday through Next Wednesday)
Issued at 329 PM CDT Wed Apr 1 2026

Upper level troughing will remain over the western CONUS on Friday
morning. Guidance is in strong consensus that an embedded closed low
will deepen as it propagates eastward from Wyoming toward Lake
Superior. In response, a surface low will move from the Central
Plains toward the Upper Great Lakes, keeping the Mid Mississippi
Valley in the warm sector through Saturday morning. Persistent warm
and moist advection in the low levels will allow instability to
build to 1000-2000 J/kg in the afternoon may be enough to force a
few thunderstorms. However, low level convergence is rather minimal
until the cold front moves into the area on Friday night/early
Saturday, while deeper forcing for ascent will be well north of the
area given the track of the upper low. Given that, deep layer shear
will also be modest (<40 kts) until the front arrives. These factors
will limit the potential for severe thunderstorms during the
afternoon and evening hours on Friday.

While the dynamics become more supportive for severe storms
overnight Friday and into Saturday morning, the thermodynamics
unsurprisingly tail off into the overnight hours. Nevertheless, we
could still see up to 500 J/kg of MUCAPE ahead of the cold front,
which coupled with upwards of 40 kts of deep layer shear and
enhanced forcing along the front, should be enough to support a
chance of severe convection overnight, perhaps in the form of a
QLCS. The current day 3 SPC outlook handles this situation well,
with the highest severe probabilities focused to the north and
west of our CWA.

Showers and a few thunderstorms may linger into Saturday morning,
but with the above cyclone will push off into eastern Canada,
relatively cool and dry deep northwest flow should put an end to any
precip by midday. This will also push Saturday`s high temperatures
nearly 20 degrees colder than what we`re expecting on Friday,
roughly 5-10 degrees below normal for early April. That northwest
upper level flow will remain in place into early next week, keeping
cooler and largely dry conditions in place across the region.

BSH

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1047 PM CDT Wed Apr 1 2026

Highest concentration of showers and thunderstorms will remain
over UIN/COU/JEF overnight and have included either predominant
or TEMPO/PROB30 groups going in those TAFS through 14Z/15Z. All of
the sites will have IFR ceilings as low as 200 feet through 10Z,
with VFR conditions not expected until 14/15Z when a warm front
will move through the area. There will be an additional chance
(30%) for showers and thunderstorms with MVFR (possible IFR)
conditions at UIN between 17-21Z and at the St. Louis are
terminals between 20-24Z on Thursday. Easterly winds around 10
knots will switch southerly behind the warm front and gust as high
as 30 to 35 knots at of the sites during the day on Thursday.

Britt

&&

.CLIMATE...
Issued at 238 AM CDT Sun Mar 29 2026

Records at Regional Long-Term Climate Sites - March 31st

             Record Highs | Record Warm Lows

St. Louis:   87F (1981)   | 63F (1917)
Columbia:    86F (1940)   | 59F (1967)
Quincy:      81F (2010)   | 58F (2010)


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through Thursday afternoon for Audrain MO-Boone MO-
     Callaway MO-Cole MO-Gasconade MO-Knox MO-Lewis MO-Marion MO-
     Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Ralls MO-
     Shelby MO.

IL...None.
&&

$$

WFO LSX