Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

783
FXUS63 KLSX 190610
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
110 AM CDT Tue May 19 2026

.KEY MESSAGES...

- Widespread showers and thunderstorms are expected to continue
  into the evening with heavy rainfall in some locations
  potentially leading to flash flooding.

- A few strong to severe thunderstorms are possible through the
  early morning hours of Tuesday with the main hazards being
  damaging winds, large hail, and a brief tornado or two.

- Another round of thunderstorms are possible along a cold front
  Tuesday afternoon/evening. Damaging wind gusts and large hail
  are the primary threats.


&&

.SHORT TERM...  (Through Late Tuesday Night)
Issued at 627 PM CDT Mon May 18 2026

Most of east-central Missouri and along I-70 in western Illinois
have observed multiple rounds of showers and thunderstorms today.
An MCV has been the impetus for this redevelopment of showers and
thunderstorms this afternoon into evening. It has also finally
dislodged the training showers and thunderstorms with convection
approaching the Mississippi River and rainfall coming to an end
behind. Highest convective rates are currently just southwest of
St. Louis, with rainfall totals now averaging 2 to 4 inches,
locally 4 to 5 inches, across the Flood Watch. There is also a
threat for a quick spin up tornado or two along with mostly sub-
severe hail. The weak tornado threat is due to an outflow that
stalled near Crawford to Washington to St. Francois Counties. We
have also had a few storms with elevated cores just below severe
limits. This is likely due to the ~7 degrees C/km mid-level lapse
rates. Convection will clear the area by 10 PM.

The end of the showers and thunderstorms will be short lived
though as another line of showers and thunderstorms has already
formed across central and eastern Kansas. This line of showers and
thunderstorms will continue to slowly move east overnight and
weaken across central Missouri. Damaging wind gusts and a brief
tornado or two will be the primary threats. How quickly the line
weakens remains the primary question. The overall thinking is that
the line will weak substantially by the time it reaches
I-70 near Columbia, MO. The weakening of the line is due to the
displacement of the showers and thunderstorms out ahead of the
cold front.

The surface cold front will likely be just northwest of Columbia,
MO Tuesday morning and stall near a Columbia, MO to Quincy, IL
line through mid-afternoon. Behind the cold front, the chance of
precipitation and severe weather is low, while ahead of the cold
front another round of showers and thunderstorms appear likely.
Surface based CAPE is forecast to be in the 2500 to 3000 J/kg
range with around 30 to 40 kt of SFC to 6 km shear. The best shear
looks to be offset from the best instability, or behind the
surface cold front. Hodographs due show some cyclonic curvature in
the lowest levels, but it is weak. Most of the forcing will also
have to come from the surface cold front. Given the above, the
environment does appear to br supportive for some supercell
development, with some storm splitting possible. As such, the
Storm Prediction Center has the region southeast of Columbia, MO
to Havana, IL in a slight risk for severe storms. Damaging wind
gusts and large hail appear to be the primary threat.

After the final round of showers and thunderstorms moves across
the area Tuesday evening, storm total rainfall amounts (from
Monday morning to Tuesday evening) of 3 to 5 inches with isolated
amounts of 6 to 8 inches appear likely. As such, have expanded the
flood watch until Tuesday afternoon.

These amounts of rainfall will result in some flash flooding.
Residents should monitor the latest forecasts and be prepared to
seek higher ground if a Flash Flood Warning is issued for your
area.

BAH

&&

.LONG TERM...  (Wednesday through Next Monday)
Issued at 251 PM CDT Mon May 18 2026

A surface cold front will be located across southern Missouri
Wednesday with most of the region expected to be seasonably cool
and dry. The one exception to this is across Reynolds, Iron and
Madison counties were another round of thunderstorms will be
possible close to the frontal boundary.

Thursday into Friday, another mid-level wave will be located over
the Mountain West with low level flow out of the southwest. As
this occurs, the cold front will wash out with temperatures rising
along with a return of showers and thunderstorms.

The warm up will then persist into the weekend and early next week
as another wave approaches from the west. This warming trend is
supported by both the LREF and NBM IQRs. Looking at global
ensemble guidance, a general building of mid-level heights is
forecast to start this weekend across the Eastern United States
and then retrograde west next week.


BAH

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 110 AM CDT Tue May 19 2026

A weakening complex of thunderstorms is currently pushing eastward
into the area, with the leading edge of strongest convection
stretching from near Quincy MO to just east of Columbia MO. Behind
the leading edge of convection, widespread stratiform rain with
occasional lightning is being observed. KCOU/KJEF just went through
the leading edge with KCOU reporting a wind gust to 33kts and brief
IFR visibilites/MVFR ceilings. As a result, within the stronger
convection, brief IFR visibilites/MVFR ceilings are expected. This
complex of convection is forecast to continue weakening with
eastward extent, resulting in lower confidence of impacts at the St.
Louis metro terminals. As of now, the leading edge is forecast to
arrive between 07-08z with around a 30% chance for IFR
visibilites/MVFR ceilings. Lingering stratiform rain is forecast for
several hours behind the convection, with visibilities forecast to
stay P6SM, aside from heavier showers that may briefly result in
MVFR visibilites.

A cold front approaches from the northwest early this morning with
MVFR/IFR ceilings expected just ahead of and behind this front.
Confidence in IFR ceilings is highest at KCOU/KJEF/KUIN, with
potential for below airport minimums on Tuesday, as indicated by the
mention of the TEMPO group. Currently, MVFR ceilings are forecast
for the St. Louis metro terminals, with the lowest ceilings (<1kft)
forecast to stay to the west. Confidence also remains low with how
quickly ceiling improve later this evening and into the night, with
guidance generally improving conditions around 06z tonight.

Ahead of the cold front, southerly winds will prevail, however,
gusty and variable winds related to showers and scattered
thunderstorms will be possible. Behind the cold front, northerly
surface winds are forecast to prevail across the area by later
this evening and continue into Wednesday.

Peine

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch until 1 PM CDT this afternoon for Audrain MO-Boone
     MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Jefferson MO-Lincoln MO-Moniteau MO-Monroe MO-Montgomery MO-
     Osage MO-Pike MO-Ralls MO-Saint Charles MO-Saint Louis City
     MO-Saint Louis MO-Warren MO-Washington MO.

IL...Flood Watch until 1 PM CDT this afternoon for Bond IL-Calhoun IL-
     Clinton IL-Fayette IL-Jersey IL-Madison IL-Marion IL-Monroe
     IL-Saint Clair IL-Washington IL.

&&

$$

WFO LSX