Flash Flood Warning 4, NWS Lincoln, IL

684 
WGUS73 KILX 072332
FFSILX

Flash Flood Statement
National Weather Service Lincoln IL
632 PM CDT Sun May 7 2023

ILC167-072342-
/O.EXP.KILX.FF.W.0004.000000T0000Z-230507T2330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Sangamon IL-
632 PM CDT Sun May 7 2023

...FLASH FLOOD WARNING HAS EXPIRED FOR SOUTHWESTERN SANGAMON 
COUNTY...

Flooding is no longer expected to pose a threat. Please continue to 
heed remaining road closures.

LAT...LON 3968 8982 3970 8954 3958 8954 3958 8983

$$

25

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
252 PM CDT Sun May 7 2023

.MESOSCALE DISCUSSION...
Issued at 251 PM CDT Sun May 7 2023

Convective initiation is ongoing mid afternoon within an area of
low level convergence that stretches from just south of
Springfield NW across Rushville in Schuyler County. Storms will
form initially within this corridor then move ENE at about 20 to
30 mph. SPC Mesoanalysis indicates a corridor of strong MLCAPE of
3000+ J/kg and sufficient deep layer shear of 30-35 kt supportive
of severe thunderstorms. Very steep mid-level lapse rates are
resulting in normalized CAPE values in excess of 0.3 (fat CAPE
profile) conducive for large hail, especially for any supercell
storm mode. Convective allowing models indicate that coverage will
increase over the next couple hours as we enter peak heating
conditions, but should stay scattered. Hydro conditions will also
need to be monitored as slow moving storms will pose some threat
for flooding.

Deubelbeiss

&&

.SHORT TERM...  (Through Late Monday Night)
Issued at 218 PM CDT Sun May 7 2023

As warm and humid air advects into central Illinois from the
west, a remnant outflow boundary from morning convection has moved
to a position from just west of Peoria, to just west of
Springfield, passing just east of the St. Louis Metro and curving
toward Paducah KY. Expect this feature to the the focus for
convective initiation this afternoon/evening. With MLCAPE near
3000 J/kg in the vicinity of this boundary and cloud layer shear
in excess of 40 knots, both large hail and severe wind gusts will
be threats from these cells. As a short wave trough moving through
northern Arkansas approaches, additional forcing for ascent along
with some degree of mid-level cooling will likely lead to fairly
broad multicell storm coverage near the outflow boundary, though
even in this situation stronger updrafts may be capable of large
hail. The expected coverage will likely lead to a growing cold
pool and another southward push of the outflow boundary this
evening, with the severity of this round of thunderstorms waning
by around 8-9 pm.

CAMs depict a second round of convection during the early morning
hours on Monday, with an organized bowing complex of thunderstorms
approaching from southern IA/northern MO. The extent of
afternoon/evening convection across central Illinois will likely
play a large role in the evolution of this complex, with the most
likely outcome at this point being a weakening complex as it moves
into central Illinois after midnight, and/or the complex following
the instability gradient to the southeast with the wind threat
remaining farther west. Even so, the potential for strong to severe
wind gusts in association with this complex will need to be watched,
especially if little convection occurs with the first round across
northern parts of the ILX forecast area. In addition, there is
potential for flash flooding with both rounds of convection,
especially where training storms occur and/or where large amounts of
rain fell early this morning.

In the wake of the early morning convective activity, expect a
fairly quiet period for at least part of the late morning/early
afternoon on Monday before thunderstorms again develop on a cold
front/the remnant outflow boundary from morning convection. MLCAPE
will be closer to 1000 J/kg, with cloud layer shear decreasing to
around 25-30 kt. Though those values are less than today, there will
still be a risk of storms producing large hail and/or severe wind
gusts Monday afternoon/evening. Expect the storms to move out of the
southeast corner of the ILX forecast area by around 9-10pm with the
cold front, with light northeast winds and relatively quiet
conditions for the rest of the overnight hours.

AAT

.LONG TERM...  (Tuesday through Next Sunday)
Issued at 218 PM CDT Sun May 7 2023

Key Messages:

1) Much quieter weather is forecast for Tuesday and Wednesday.

2) Precipitation chances increase once again from Thursday into the
weekend.

A mid-level ridge will amplify over the Midwest from Tuesday into
Wednesday, with minimal precipitation chances and high temperatures
falling back into the mid to upper 70s. Precipitation chances begin
to return on Thursday in association with a closed low moving from
the northern/central Rockies into the upper Midwest. Cluster
analysis shows ensemble member differences regarding the depth and
speed/track of this low, which will eventually affect where and how
much precipitation falls. Even so, this period doesn't look terribly
high-impact at this point, with NBM probability of rainfall > 1" in
the entire Friday-Sunday period only in the 20-30% range. However,
we'll need to keep an eye out for substantial rainfall accumulations
where soils are becoming more saturated. Additionally, the grand
ensemble (GEFS/EC/CMC) mean CAPE in the Fri/Sun period does poke up
between 500-1000 J/kg during the afternoons.

AAT

&&

.AVIATION...  (For the 18z TAFs through 18z Monday Afternoon)
Issued at 1222 PM CDT Sun May 7 2023

VCSH were removed from the first couple hours of the TAFs, as
we've still some time to destabilize thanks to the outflow from
this morning's storms. Ultimately, however, surface heating should
prove sufficient for convection to reignite along that residual
boundary and subsequently propagate northeastward across central
Illinois. In the meantime, south winds around 10-15 (G20) kt will
continue as the bases of scattered to broken stratocumulus rise
out of the MVFR category at CMI and PIA. There's still
considerable timing and locational uncertainty with the storms to
develop late this afternoon and evening, but confidence increases
in widespread thunderstorms later tonight - mainly after around
08z (3 AM). Both rounds of storms will carry the potential for
erratic and intense (locally > 50 kt) surface wind gusts, large
hail, and frequent lightning, but at this time the late afternoon-
evening activity has the greatest potential to be severe.

Bumgardner

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

WFO ILX

Hazardous Weather Outlook
National Weather Service Lincoln IL
312 PM CDT Sun May 7 2023

ILZ027>031-036>038-040>057-061>063-066>068-071>073-081645-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Champaign-Vermilion-Cass-Menard-Scott-
Morgan-Sangamon-Christian-Macon-Moultrie-Douglas-Coles-Edgar-Shelby-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
312 PM CDT Sun May 7 2023

This Hazardous Weather Outlook is for central Illinois, east
central Illinois, southeast Illinois and west central Illinois.

.DAY ONE...This afternoon and tonight.

Scattered thunderstorms are expected to develop this afternoon and
persist into early evening, focused along an outflow boundary from
near Springfield to just west of Peoria. Storms this evening should
develop near this boundary, then move east-northeast at around 20 to
30 mph. Tonight, a line of storms will likely develop and push
southeast across central IL after midnight. Both rounds of
thunderstorms could be severe with damaging winds and large hail
being the primary hazards. An isolated flash flood risk may develop
if thunderstorms repeatedly affect the same location.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Periods of thunderstorms are expected ahead of a cold front on
Monday. Severe storms will again be possible. Damaging wind gusts
and large hail are the primary hazards. An isolated flash flood risk
may develop if thunderstorms repeatedly affect the same location.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and tonight.

25/AAT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
1107 AM CDT SUN MAY 7 2023

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

1200 AM     TSTM WND DMG     BEARDSTOWN              40.01N 90.43W
05/07/2023                   CASS               IL   LAW ENFORCEMENT

            POWERLINES DOWN ON RAILROAD TRACKS. TIME
            ESTIMATED FROM RADAR.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
1108 AM CDT SUN MAY 7 2023

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

1218 AM     TSTM WND DMG     CHANDLERVILLE           40.05N 90.15W
05/07/2023                   CASS               IL   LAW ENFORCEMENT

            LARGE TREE LIMBS DOWN. TIME ESTIMATED FROM
            RADAR.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
306 PM CDT SUN MAY 7 2023

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

0302 PM     HAIL             CHATHAM                 39.68N 89.70W
05/07/2023  M1.75 INCH       SANGAMON           IL   TRAINED SPOTTER

            GOLF BALL SIZE HAIL IN CHATHAM.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
308 PM CDT SUN MAY 7 2023

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

0259 PM     HAIL             CHATHAM                 39.68N 89.70W
05/07/2023  M1.00 INCH       SANGAMON           IL   TRAINED SPOTTER

            QUARTER SIZE HAIL IN CHATHAM.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
312 PM CDT SUN MAY 7 2023

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

0304 PM     HAIL             CHATHAM                 39.68N 89.70W
05/07/2023  E1.25 INCH       SANGAMON           IL   PUBLIC

0309 PM     HAIL             1 E AUBURN              39.59N 89.73W
05/07/2023  M1.25 INCH       SANGAMON           IL   MESONET

            SOCIAL MEDIA REPORT VIA TWITTER.

&&

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LINCOLN IL
317 PM CDT SUN MAY 7 2023

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

0314 PM     HAIL             AUBURN                  39.59N 89.74W
05/07/2023  M2.00 INCH       SANGAMON           IL   MESONET

            UP TO 2 INCH DIAMETER HAIL MEASURED. SOCIAL
            MEDIA REPORT WITH PHOTO ON TWITTER.

&&