Old Jamestown, Missouri 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

626
FXUS63 KLSX 111112
AFDLSX

Area Forecast Discussion
National Weather Service St Louis MO
612 AM CDT Sat Jul 11 2026

.KEY MESSAGES...

- Localized flash flooding is possible today. A flash flood
  watch remains in effect through 7PM.

- An isolated severe thunderstorm is possible, mainly over far
  southeast Missouri and southwest Illinois. The primary threat
  is damaging winds.

- Mainly dry and near normal temperatures are forecast through the
  upcoming week.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 301 AM CDT Sat Jul 11 2026

Scattered showers and thunderstorms are expected across the area
through late this afternoon. Locally heavy rain will accompany
thunderstorms with localized rainfall rates of up to 1-2" per hour.
Considering the saturated surfaces, rainfall will largely be
attributed to runoff with the potential for rapid rises on nearby
streams and tributaries. Activity gradually shifts southward late
this evening with improving conditions Sunday into Monday. Mild and
dry conditions are favored at the start of next week.

GOES-19 water vapor imagery shows an upper level shortwave rotating
southward out of Iowa early this morning. A remnant outflow boundary
extends from east to west through portions of southern Illinois and
southern Missouri, where IR satellite initially showed convective
cells lining up from southwest Illinois through southwest Missouri.
Fortunately, this setup is not quite the same as last night as the
line slightly meanders north/south and is less concentrated than
last night`s event. A low level jet of 30-35 knots remain intact
through about 12z with the left exit region pointed at southeast and
east-central Missouri. However, it`s not quite as strong and
elongated as yesterday. Recent IR satellite trends shows cloud tops
have warmed since just a couple of hours ago. While additional
development is expected to percolate through southern sections of
MO/IL, the long duration of concentrated training is looking like
far less of a threat this morning as the pattern begins to shift.
The mid/upper shortwave steers overhead this morning through late
this afternoon, causing flow to turn out of the northeast, which
will begin to lower flash flood concerns in time as heavier rainfall
become more isolated or widely scattered. A stronger thunderstorm or
two cannot be entirely ruled out but the support shifts southward
into southern MO/IL where 40-45 knots of shear and high CAPE values
will be more favorable. This trend continues tonight into Sunday as
northeasterly surface flow shunts higher moisture to the south with
dewpoints falling 5-10 degrees by late Sunday. Upper level ridging
then begin to build from west to east as we enter next week. This
sets up for a rather nice end to the weekend and start to the work
week.

Temperatures are expected to be seasonably cool to near normal with
highs in the 80s and lows in the 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 301 AM CDT Sat Jul 11 2026

Warmer conditions are expected through the upcoming week with rain
chances centered on Tuesday afternoon and evening over southeast
Missouri and southwest Illinois. Heat is not expected to have the
same intensity as the recent hot period with lower moisture
accompanying warmer temperatures.

Global guidance continues to show some version of a strong upper
level ridge building from the Intermountain West into the northern
Plain by Tuesday. Both ECM/GFS depict an elongation of the ridge,
which at least briefly extends through much of the northern half of
the CONUS. What`s more captivating is the anomalous height rises,
which peak at 3-4 standard deviations above normal early
Tuesday. The upper shortwave that is currently passing over the
region temporarily becomes stationary over the western
Tennessee Valley before it is ejected westward around the
southern edge of the upper ridge. At that time, surface
dewpoints return back to the upper 60s to mid-70s, providing
additional moisture for rain chances to return. Weak
southeasterly flow and shear of less than 15 knots indicates
that what materializes will more than likely be diurnally driven
with chances topping out around 50% Tuesday afternoon/evening.
This upper level system continues to move westward through the
later half of the week, but that is also where long range
guidance begins to diverge on the handling of the upper ridge.
Beyond Tuesday, rain chances remain below 20%.

Temperatures return to the upper 80s/low-90s for highs with morning
lows in the upper 60s to low-70s.

&&

.AVIATION /12Z TAFS THROUGH 18Z SUNDAY/...
Issued at 612 AM CDT Sat Jul 11 2026

Scattered showers and thunderstorms will track through the
region from northwest to southeast today. Showers will be
possible through most of the day, while thunderstorm potential
will be highest through the afternoon and early evening. MVFR
ceilings are expected to progress from northeast Missouri and
over the metro terminals this morning with localized IFR
conditions in and around more efficient showers/thunderstorms.
The potential for a thunderstorm is present through much of the
day, though the chances will be highest roughly 20z-23z. Rain
tracks to the southeast overnight with improvement expect
through the end of the period.

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Flood Watch through this evening for MOZ047>049-059-062-065-
     072>075-084-085-099.
IL...Flood Watch through this evening for ILZ079-102.

&&

$$

SHORT TERM...Maples
LONG TERM...Maples
AVIATION...Maples