Flash Flood Warning 10, NWS St. Louis, MO

487 
WGUS73 KLSX 272334
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
634 PM CDT Mon Apr 27 2026

ILC001-149-MOC127-173-280245-
/O.CON.KLSX.FF.W.0010.000000T0000Z-260428T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Adams IL-Pike IL-Marion MO-Ralls MO-
634 PM CDT Mon Apr 27 2026

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 945 PM CDT THIS
EVENING FOR ADAMS AND NORTHWESTERN PIKE COUNTIES IN WEST CENTRAL
ILLINOIS AND CENTRAL MARION AND NORTHERN RALLS COUNTIES IN
NORTHEASTERN MISSOURI...

At 634 PM CDT, Flash flooding will continue due to excessive runoff,
even though heavy rain has ended. Between 2 and 4 inches of rain have
fallen.

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Radar indicated.

IMPACT...Flash flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other poor
         drainage and low-lying areas.

Some locations that will experience flash flooding include...
  Quincy, Hannibal, Palmyra, Monroe City, Quincy Regional Airport,
  Camp Point, Payson, New London, Clayton, Golden, Fall Creek,
  Center, Beverly, Rensselaer, Spaulding, Adams, Kingston, Burton,
  Liberty and Hull.

This includes the following highways...
Interstate 72 between exits 4 and 10. Interstate 172 between exits 2
and 19.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3960 9172 3981 9171 3995 9151 3995 9144
      3996 9145 3998 9146 4003 9139 4015 9092
      3975 9093 3943 9172 3948 9171 3960 9171

FLASH FLOOD...RADAR INDICATED

$$

Carney

304 
WGUS73 KLSX 280213
FFSLSX

Flash Flood Statement
National Weather Service St Louis MO
913 PM CDT Mon Apr 27 2026

ILC001-149-MOC127-173-280223-
/O.CAN.KLSX.FF.W.0010.000000T0000Z-260428T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Adams IL-Pike IL-Marion MO-Ralls MO-
913 PM CDT Mon Apr 27 2026

...FLASH FLOOD WARNING IS CANCELLED FOR ADAMS AND NORTHWESTERN PIKE
COUNTIES IN WEST CENTRAL ILLINOIS AND CENTRAL MARION AND NORTHERN
RALLS COUNTIES IN NORTHEASTERN MISSOURI...

 The heavy rain has ended. Flood waters have receded. Flooding is no
 longer expected to pose a threat. Please continue to heed remaining
 road closures.

&&

LAT...LON 3960 9172 3981 9171 3995 9151 3995 9144
      3996 9145 3998 9146 4003 9139 4015 9092
      3975 9093 3943 9172 3948 9171 3960 9171

$$

Carney

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
647 AM CDT Mon Apr 27 2026

.KEY MESSAGES...

- While periods of storms are expected through Monday morning, the most
  potent thunderstorms will occur this afternoon and evening.

- Thunderstorms this afternoon and evening will be capable of
  damaging wind gusts, large hail, and strong tornadoes.

- A period of cool, calm weather is expected mid-week through the
  weekend.

&&

.SHORT TERM... (Through Tuesday Night)
Issued at 155 AM CDT Mon Apr 27 2026

Storms across southeastern Missouri continue to butt up against an
instability gradient draped from north to south across Missouri.
The warm air advection feeding these storms will also push greater
instability slowly northeastward through this morning, though
propagation vectors will favor convection continuing to move east-
southeastward generally away from the CWA or into an unfavorable
environment. Additionally, the low-level jet refocusing across
Kansas will continue to support the downward trend in convection
across southeastern Missouri early this morning. Any linger storms
over the next couple of hours will be capable mainly of large hail,
though there is also a very low damaging wind and tornado threat for
storms that remain surface based.

Our attention turns to the storms over eastern Kansas that are
propagating eastward with the nose of the low-level jet. With the
nose of this low-level jet edging into northeastern Missouri later
this morning, the focus for these storms will spread into portions
of the CWA north of I-70. Vertical thermal profiles suggest that this
convection will be elevated, mitigating a threat of damaging wind
gusts and/or tornadoes. However, with around 40 kts of effective
shear and building MUCAPE, there is a low chance for isolated
instances of large hail.

How long this convection lingers is uncertain, although guidance
trends have been toward a lull in convective activity in the wake of
this convection and that associated with a cold front during the
late afternoon and evening. Ahead of the front, the warm sector
remains capped through much of the afternoon per a majority of
deterministic soundings. Although, any remnant outflow or
differential heating boundary from early day convection may serve as
enough of a forcing mechanism to spawn discrete convection during
the afternoon as lift from an approaching shortwave increases over
the region. If this convection does form, it will be in an
environment characterized by 2,000-2,500 J/kg of SBCAPE and roughly
50 kts of deep-layer shear. This will favor supercells capable of
all hazards, with long curved hodographs favoring strong tornadoes,
especially if storms are able to latch on to any remnant boundaries
across the CWA.

Where the environment isn't contaminated from earlier rounds of
convection, additional updrafts are expected along the cold front as
it enters the area 4-5pm. Forcing from the front paired with lift
from the shortwave will lead to numerous updrafts along the front.
While this will be occurring within a similar environment detailed
prior, the number of updrafts paired with them occurring along the
front may lead to destructive interactions and congealing into line
segments and/or clusters. While this will tend to limit a strong
tornado threat, storms will still be capable of all severe hazards.
Convection is expected to depart the CWA with the front by 9-10pm.

Even with the FROPA Monday evening, the threat for convection will
continue on Tuesday. Guidance consensus has the front stalling just
south of the CWA early Tuesday and then buckling northward as a
shortwave moves through the Central Plains and into the Midwest
through the day. This shortwave will send a subtle surface
reflection through the Mid South along the front, with a brief
period of warm air advection that will help force elevated
convection for areas mainly along and south of I-70. If the front
can move northward enough, shear profiles and instability amounts
favor supercells capable primarily of large hail across far
southeastern Missouri during the afternoon. Waning instability and
the front continuing southward will bring an end to rain chances
during the evening.

Elmore

&&

.LONG TERM... (Tuesday Night through Sunday)
Issued at 155 AM CDT Mon Apr 27 2026

Both deterministic guidance and ensemble clusters keep upper-level
troughing slowly moving eastward over the eastern CONUS through the
long range forecast period. This will maintain northwesterly flow
over the Middle Mississippi Valley through Saturday as several
rounds of high pressure pass through the region. As a result,
temperatures will run at or below climatological normals into the
weekend and mostly dry weather is expected.

Elmore

&&

.AVIATION...  (For the 12z TAFs through 12z Tuesday Morning)
Issued at 647 AM CDT Mon Apr 27 2026

Thunderstorms are expected at times throughout the day, impacting
all terminals. The greatest coverage of thunderstorms this morning
is expected to be across central, northeastern MO into west-central
IL impacting KCOU, KJEF, and KUIN, with lower confidence in
thunderstorms reaching the St. Louis metro terminals through early
afternoon. Another round of redevelopment will take place this
afternoon and evening with the greatest chance of severe
thunderstorms as well. These thunderstorms will be capable of hail,
strong winds, and some tornadoes. Trends will need to be monitored
for more significant terminal impacts beyond MVFR to IFR flight
conditions.

A cold front will pass through the region this evening, veering
southerly winds to northwesterly with drier conditions prevailing.
There is the potential for some post-frontal MVFR ceilings late
tonight into Tuesday morning, with the highest chance of impacts at
KUIN. However, given that confidence is low in impacts before the
end of the TAF period, VFR flight conditions are maintained for
now.

Pfahler

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service St Louis MO
202 AM CDT Mon Apr 27 2026

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-280715-
Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-
Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL-
Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO-
Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO-
Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-
Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO-
Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
202 AM CDT Mon Apr 27 2026

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Today and tonight.

Periods of thunderstorms are expected through the day into this
evening. Thunderstorms this afternoon and evening will be capable of
large hail, damaging wind gusts, and tornadoes.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

There is a chance of thunderstorms Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report wind damage, hail occurrence and
size, and tornado occurrence to NWS St. Louis.

Elmore

Preliminary Local Storm Report
National Weather Service St Louis MO
352 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0319 PM     Hail             5 NE Columbia           39.01N 92.28W
04/27/2026  E1.00 Inch       Boone              MO   Public

            Report from mPING: Quarter (1.00 in.).

&&

Preliminary Local Storm Report
National Weather Service St Louis MO
359 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0359 PM     Hail             3 NW Rush Hill          39.24N 91.78W
04/27/2026  E1.00 Inch       Audrain            MO   Public

&&

Preliminary Local Storm Report
National Weather Service St Louis MO
400 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0355 PM     Hail             1 WNW Mexico            39.17N 91.88W
04/27/2026  E1.50 Inch       Audrain            MO   Public

&&

Preliminary Local Storm Report
National Weather Service St Louis MO
413 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0410 PM     Hail             3 NW Rush Hill          39.24N 91.78W
04/27/2026  E1.00 Inch       Audrain            MO   Public

            Second round of quarter-sized hail.

&&

Preliminary Local Storm Report
National Weather Service St Louis MO
443 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0440 PM     Hail             3 NW Rush Hill          39.24N 91.78W
04/27/2026  E1.00 Inch       Audrain            MO   Public

            third round of quarter-sized hail.

&&

Preliminary Local Storm Report
National Weather Service St Louis MO
446 PM CDT Mon Apr 27 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0446 PM     Hail             California              38.63N 92.57W
04/27/2026  E0.70 Inch       Moniteau           MO   Public

&&