Flash Flood Warning 54, NWS St. Louis, MO

175 
WGUS73 KLSX 102238
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
538 PM CDT Fri Jul 10 2026

MOC221-102248-
/O.CAN.KLSX.FF.W.0054.000000T0000Z-260710T2245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Washington MO-
538 PM CDT Fri Jul 10 2026

...FLASH FLOOD WARNING FOR SOUTHWESTERN WASHINGTON COUNTY IN EAST
CENTRAL MISSOURI HAS BEEN REPLACED WITH A FLOOD WARNING...

&&

LAT...LON 3779 9086 3774 9083 3773 9086 3773 9089
      3774 9098 3774 9110 3784 9110

$$

Pfahler

Area Forecast Discussion
National Weather Service St Louis MO
252 PM CDT Fri Jul 10 2026

.KEY MESSAGES...

- The threat for (additional) flash flooding remains the top
  concern through Saturday. Areas that saw 6-12+" of rain are
  most susceptible to additional flooding.

- A few storms may be strong to severe this afternoon/evening
  and again Saturday afternoon. Damaging winds are the primary
  threat.

- Drier weather with temperatures close to normal is forecast
  Sunday into next week.

&&

.SHORT TERM /THROUGH SATURDAY/...
Issued at 248 PM CDT Fri Jul 10 2026

GOES-19 water vapor imagery shows a pronounced midlevel
shortwave across the mid-Missouri Valley moving east. Lift along
with cooling temperatures aloft should help initiate additional
convection over the next couple of hours, most likely
east/southeast along a weak surface frontal boundary/trough
axis. This is where convergence is strongest near the surface.
There may also be another more subtle disturbance in southeast
Kansas/southwest Missouri. This feature is also moving east, and
instability is building downstream across southeast Missouri.
The latest SPC mesoanalysis shows over 2000 J/kg of MLCAPE with
little/no CIN. There is not perfect overlap between the higher
instability (in southeast Missouri) with the higher effective
shear, which resides in northeast Missouri downstream of the
aforementioned midlevel shortwave trough. A few storms across
the area may be strong to severe from late this afternoon
through mid/late evening, with damaging winds the primary
threat.

The main concern however continues to be on the heavy rainfall
threat and the potential for renewed flash flooding. Weather wise,
we are expecting the coverage of showers and thunderstorms to
increase late this evening into the early overnight hours as the low-
level jet strengthens. The jet is quite a bit weaker than last
night, so we are not expecting as much organization as last night
and overall amounts should be a lot less. However, ANY significant
rainfall in the northwest-southeast axis across southeast Missouri
that saw 6-12+" of rain will be of greatest concern and
susceptibility. Unfortunately, it does appear that areas south of I-
70 in Missouri are more likely to see the heavier rainfall totals
tonight. The LPMM of the HREF and REFS show pockets of 1" to as much
as 3" through Saturday morning, and this aligns well with our
expectations.

The synoptic midlevel shortwave trough is forecast to gradually move
south/southeast on Saturday beneath the amplifying mid/upper level
ridge. The wave has trended farther south/southwest (and slower)
with time. That means a continued threat for at least scattered
showers and thunderstorms through much of the day on Saturday, with
a focus along/ahead of this feature. That means east/southeast
Missouri and southwest Illinois will be most favored for additional
showers/thunderstorms. Needless to say, any rainfall in parts of
southeast Missouri would not be good. Total rain amounts of 2-4"
through Saturday afternoon are possible in the watch area, with
locally higher amounts potentially within locations that get
repeatedly impacted.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Issued at 248 PM CDT Fri Jul 10 2026

(Saturday Night - Sunday)

The midlevel wave/closed low should move far enough south to end the
heavy rainfall threat Saturday night, though we will have to keep a
close eye on its equatorward progression. Even slower guidance
though focuses the low-level jet well to the south of our CWA, so
while some shower activity or even a rumble of thunder may linger in
our southern counties early Saturday night, the expectation is for
the threat for (new) flash flooding to be over.

Isolated to widely scattered showers/weak thunderstorms may
redevelop Sunday afternoon near the closed low/shear axis. Similar
to Saturday night though, the threat for flash flooding looks quite
low. The atmosphere is also not as supportive as warm cloud depths
are not as deep and precipitable water values drop to near 1.6"
(~75th percentile) of climatology. Therefore, any individual
showers/weak thunderstorms should not be nearly as efficient as days
prior.

(Sunday Night - Next Friday)

There has been a subtle shift in the mid/upper level pattern into
early/mind next week. While the record-breaking ridge will still
build to our north across the northern Plains and Upper Midwest, the
pesky midlevel shortwave/shear axis now seems likely to retrograde
westward around the southern periphery of the ridge. This means
continued low (~15-30%) chances of showers/weak thunderstorms mainly
in central/southeast Missouri and focused diurnally. Similar to
Saturday night/Sunday, there should not be any real organization or
threat for strong-severe convection nor flash flooding. The
proximity of the midlevel shortwave/shear axis though should tend to
lead to cooler temperatures due to the rain chances mentioned above
and associated cloud cover. Temperatures are now likely to stay
close to normal through at least the middle of next week, if not the
entire week.

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1221 PM CDT Fri Jul 10 2026

Scattered showers and thunderstorms are expected to redevelop by
mid-late afternoon. There is uncertainty on where storms will be
favored initially, but should tend to shift southward overnight
into Saturday. Brief reductions in visibility along with the
possibility of gusty winds are the main concerns from an
aviation perspective. Lower ceilings are also expected to
develop late tonight, with the best chances at KCOU/KJEF.

&&

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

&&

SHORT TERM...Gosselin
LONG TERM...Gosselin
AVIATION...Gosselin