Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

826
FXUS63 KLSX 101056
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
556 AM CDT Tue Mar 10 2026

.KEY MESSAGES...

- Near record-high temperatures are possible again Today.

- Severe thunderstorms are possible, mainly late this afternoon
  and evening across northeastern MO/west-central IL if storms can
  develop. The threat for severe storms continues overnight
  across much of the area, however it is not as likely.

- Locally heavy rainfall is also possible overnight tonight into
  Wednesday morning.


&&

.SHORT TERM...  (Through Late Wednesday Afternoon)
Issued at 341 AM CDT Tue Mar 10 2026

The primary concern in the short-term remains the potential for
severe thunderstorms late this afternoon and tonight.  Low pressure
developing over the Great Plains will shift east-northeast this
afternoon and tonight along a quasi-stationary front over southern
Iowa.  Persistent southerly flow across Missouri and Illinois will
continue to bring moisture from the Gulf into the Mid Mississippi
Valley today, and strong March sunshine will push temperatures to
near record levels again in the low to mid 80s.  RAP and GFS are
showing ~2500 J/Kg MLCAPE developing this afternoon south of the
front, with 40-50kts of 0-6km shear.  Additionally, forecast
soundings show a solid amount of CAPE in the hail-growth zone, so
supercells with large/very large hail continue to be possible...if
storms can develop during the late afternoon/early evening.

In addition to the impressive CAPE profiles and kinematics, forecast
soundings also show a capping inversion which may be too strong for
updrafts to punch through.  Indeed, most guidance now keeps our
forecast area dry until mid-late evening when the low moves into
northern Illinois which drags the front into northeast Missouri. I`m
not confident enough to totally remove PoPs during the afternoon and
early evening just yet, however the chance for afternoon/evening
storms does appear to be lower than previously thought so have kept
PoPs in the 30-50 percent range across central and northeast
Missouri/west central Illinois.  If storms do form, all severe
hazards will be possible including the aforementioned hail, as well
as damaging straight-line winds and a few tornadoes.  Precipitable
water values and warm cloud depths remain favorable for efficient
rainfall production tonight as well.  However, CAMs aren`t showing
much in the way of training.  WPC has downgraded our area to
"marginal" from "slight" in the day one excessive rainfall outlook
as well.  Have therefore opted not to issue a flood watch at this
time.  Rain and thunderstorms will end from northwest to southeast
on Wednesday as the cold front moves through the area. Highs on
Wednesday will likely occur during the morning and temperatures will
fall through the day behind the cold front.

Carney

&&

.LONG TERM...  (Wednesday Night through Monday)
Issued at 341 AM CDT Tue Mar 10 2026

Wednesday night through Saturday night continues to look relatively
quiet with near to above normal temperatures.  High pressure builds
into the Mid Mississippi Valley Wednesday night into Thursday behind
the cold front.  A short wave trough then moves from the Northern
Plains through the Upper Midwest and into the Great Lakes Thursday
night into Friday.  The surface clipper system pushes a cold front
into Missouri and Illinois Friday where it stalls and then moves
back to the north on Saturday.  Near normal temperatures in the low
to mid 50s are likely on Thursday under the influence of the high.
Temperatures become less certain for Friday and Saturday as the
clipper system`s front waves across the area. Current indications
are that there will be a 10-15 degree temperature gradient from
north to south across the area ranging from the mid 50s to around 70
on Friday and from the low 60s to low 70s on Saturday.  Of course
the differences in the position of the front make these temperature
ranges uncertain with both the NBM and LREF showing 8-10 degree high
temperature IQRs both days.

Another, much stronger short wave trough digs into the Plains on
Sunday.  The surface low moves across the Midwest and pushes a
strong cold front through Missouri and Illinois. Current indications
are that the majority of the precip associated with this system will
be post-frontal, with very little instability in the warm sector.
Rain should be the primary precip type, however temperatures drop
quickly behind the front so some wet flakes are possible late Sunday
afternoon and Sunday evening. Deterministic guidance shows drier air
moving in and shutting off the precip before any significant
accumulations can occur.  A cold/dry Canadian high moves in behind
the cold front with temperatures closer to January`s normals than
mid March.  Latest guidance shows teens and 20s Monday morning and
highs struggling to reach the mid to upper 30s Monday afternoon.

Carney

&&

.AVIATION...  (For the 12z TAFs through 12z Wednesday Morning)
Issued at 548 AM CDT Tue Mar 10 2026

VFR flight conditions and gusty southerly flow is expected to
prevail at least into mid to late afternoon. There is a chance for
scattered strong to severe thunderstorms developing ahead of a
cold front across northeast and central Missouri into west central
Illinois, mainly after 00Z this evening. Evening storms may
produce 2+ inch diameter hail, wind gusts in excess of 50kts and
possibly tornadoes.  Thunderstorms are expected to become more
numerous, likely affecting most of if not the entire area between
06-12Z. Thunderstorms are expected to weaken as they become more
widespread, but will still be capable of gusty winds and locally
heavy rain.

Carney

&&

.CLIMATE...
Issued at 350 AM CDT Tue Mar 10 2026

Near record high temperatures are possible again today.

            Today 3/10
KSTL        86F (1955)
KCOU        82F (1955)
KUIN        79F (1955)


&&

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

$$

WFO LSX