Severe Thunderstorm Warning 167, NWS Lincoln, IL

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1247 PM CDT Thu Jun 29 2023

.SYNOPSIS...
Issued at 1238 PM CDT Thu Jun 29 2023

Another round of severe thunderstorms are expected to track
quickly eastward over central and southeast IL during this
afternoon, with all hazards possible. This includes damaging winds
of 60 to 80 mph, large hail 1 to 3 inch diameter and possible
tornadoes along with heavy rains. Highs today in the mid to upper
80s with muggy and hazy conditions before the storms. An air
quality alert continues through 7 pm today, but smokey conditions
should improve as the storms race eastward across central IL
through this afternoon. More severe weather is possible Friday
and this weekend with more rounds of thunderstorms.

&&

.DISCUSSION...
Issued at 249 AM CDT Thu Jun 29 2023

-----------------------[KEY MESSAGES]-----------------------

1. Severe weather is on deck for today, with the potential of
multiple rounds throughout the day. All hazards are possible.

2. Smoke lingers over central Illinois with hopes that it will move
out by this morning into the afternoon.

------------------------[DISCUSSION]------------------------

Looking at the set up today synoptically, we can see a prominent
500 mb ridge in place over much of the central United States. Many
of the convective complexes look as if they are "riding the
ridge", moving over the top of the ridging feature. This ridge is
likely a big player in the extreme temperatures much of the United
States will be dealing with for the next day or so, essentially
acting as a heat dome. However, the convection expected today will
limit temperatures. An upper level trough is pushing onto the
west coast. This will force the ridging pattern to weaken and move
off to the east and bring additional chances for rain and
thunderstorms to our CWA.

A surface low pressure system is moving across the Plains eastward
towards the Middle Mississippi and Ohio Valleys. The warm front
associated with this low will bring dewpoints of 70+ degrees to
central and southeastern Illinois. These dewpoints indicate the
abundance of moisture in the air, which will help aid in the
convective initiation in the early morning hours today. After the
warm front and surface low move away from central Illinois, multiple
surface boundaries are forecast to pass through over the next
several days.

Dropping down to the mesoscale details, we shall focus on the near
term (Thursday into Friday). As the storms begin to fire up this
morning, they are expected to be primarily elevated to start as they
are ahead of the warm front. These early storms' risks look to
mainly be hail, as there is quite a bit of capping that the winds
will have to break through to reach the surface. Depending on
location of the convective complex passage and its associated cold
pool, storms may be able to become surface based, which will greatly
increase the risk of strong, damaging winds. The storms that are
along or near the warm front have a chance for some tornadoes. SPC
has all of central Illinois in an enhanced risk for severe weather
[5% tor, 30% wind, and 15% hatched hail].

Based on the 00z/29 run of the NAM, MUCAPE values are widely 2500-
5000 J/kg for most of the night into Thursday afternoon/evening. The
capping over the region is keeping SBCAPE pretty low over eastern
Illinois but nearing 4000 J/kg over western Illinois. The surface to
500mb bulk shear shows a max of 50 kts over central Illinois this
morning (agreeing with the Euro/GFS/HRRR). The 00z/29 run of the
HREF ensemble show large swaths of areas with updraft speeds greater
than 20 m/s (sufficient for hail development).

The first round of convection is expect to start making its way
across the CWA just before sunrise. The second round closely follows
and potentially will move through by late morning or early
afternoon. Then a third round could move through by late tonight or
early Friday morning. Despite it being the extreme short term now,
there is still the uncertainty of where these complexes may move
through and how they will affect each other and the highs over the
next day or so.

In terms of the smoke and hazy conditions, the HRRR 00z run is
indicating that the smoke should start clearing out of the area just
after sunrise. Visibilities and air quality should begin to improve
shortly after. Basically, today is going to be much less smokey and
hazy than the previous 2 days.

If the convection plays out as expected, temperatures will be
greatly limited today and Friday - essentially depleting the heat
indices. The heat advisory for Lawrence/Richland/Clay counties has
been cancelled early. Saturday - Monday will see highs primarily in
the upper 80s but then by mid week highs in the 90s will return.
Currently, there is no heat indices in the forecast. There is a
chance for showers and thunderstorms throughout the extended period.

Delaney

&&

.AVIATION...  (For the 18z TAFs through 18z Friday Afternoon)
Issued at 1245 PM CDT Thu Jun 29 2023

Severe squall line racing eastward along I-55 and already affected
PIA and SPI with w/nw wind gusts 45-55 kts and about to affect
DEC and BMI prior to 18Z. Severe storms racing east at 55-65 mph
and to affect CMI by 1830-19Z with w/nw wind gusts 50-60 kts
likely. Hail and very heavy rains also risk along and east of the
IL river next 1-2 hours with IFR to MVFR conditions. A lull in
convection from this evening into mid Fri morning, but another
round of convection could roll in late Friday morning or Friday
afternoon. CAMs differ on evolution of next round of convection on
Fri and left thunderstorms out of TAFs for Friday morning.

07

&&

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

Hazardous Weather Outlook
National Weather Service Lincoln IL
1128 AM CDT Thu Jun 29 2023

ILZ027>031-036>038-040>057-061>063-066>068-071>073-301630-
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-
1128 AM CDT Thu Jun 29 2023

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

.DAY ONE...This afternoon and tonight.

Unhealthy air quality remains a concern today, though significant
improvements are expected this afternoon.

A line of severe thunderstorms capable of widespread damaging wind
gusts will move through central Illinois from roughly 1145 AM through
3 PM Thursday. Isolated instances of large hail and a tornado or two
will also be possible.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

There is 30-50% chance for thunderstorms Friday through Sunday.
Severe storms are possible Friday and Saturday, with damaging winds
and hail the primary hazards.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed through 4 PM.

Expected storm motion is toward the east around 60 mph.

Bumgardner

Preliminary Local Storm Report
National Weather Service Lincoln IL
1242 PM CDT Thu Jun 29 2023

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

1207 PM     Tstm Wnd Dmg     4 SSW Alta              40.77N 89.66W
06/29/2023                   Peoria             IL   NWS Employee

            Large branch down, approximately five inches
            in diameter.

1207 PM     Tstm Wnd Dmg     4 SSW Alta              40.76N 89.67W
06/29/2023                   Peoria             IL   NWS Employee

            Large tree blown over, approximately 18
            inches in diameter. Time estimated by radar.

1227 PM     Tstm Wnd Dmg     2 NNW Lincoln           40.17N 89.38W
06/29/2023                   Logan              IL   NWS Employee

            Two foot diameter tree blown down. Shingles
            blown off apartment complex. Possibly caused
            by tornado. Time estimated by radar.

&&

Erwin

Preliminary Local Storm Report
National Weather Service Lincoln IL
1252 PM CDT Thu Jun 29 2023

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

1140 AM     Tstm Wnd Dmg     Canton                  40.56N 90.04W
06/29/2023                   Fulton             IL   Trained Spotter

            One foot diameter tree limb down, causing
            damage to patio furniture. Time estimated by
            radar.

1220 PM     Tstm Wnd Dmg     1 SW Springfield        39.80N 89.66W
06/29/2023                   Sangamon           IL   Trained Spotter

            Large tree limbs down at intersection of
            Spring and Edwards in Springfield.

1224 PM     Tstm Wnd Dmg     1 N Spaulding           39.88N 89.54W
06/29/2023                   Sangamon           IL   Public

            Report from mPING: 3-inch tree limbs broken.
            Time estimated by radar.

&&

Erwin

Preliminary Local Storm Report
National Weather Service Lincoln IL
1259 PM CDT Thu Jun 29 2023

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

1227 PM     Tstm Wnd Gst     1 NNW Lincoln           40.16N 89.37W
06/29/2023  E60 MPH          Logan              IL   Cocorahs

1238 PM     Tstm Wnd Dmg     1 NW Taylorville        39.56N 89.31W
06/29/2023                   Christian          IL   Public

            Large branches down, gutters and shingles
            blown off.

1250 PM     Tstm Wnd Dmg     3 SW Decatur            39.82N 88.98W
06/29/2023                   Macon              IL   Emergency Mngr

            Downed tree took out power lines near
            Enterprise School.

1254 PM     Tstm Wnd Gst     Decatur Airport         39.83N 88.86W
06/29/2023  M75 MPH          Macon              IL   ASOS

&&

Erwin

Preliminary Local Storm Report
National Weather Service Lincoln IL
103 PM CDT Thu Jun 29 2023

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

1225 PM     Tstm Wnd Dmg     Dawson                  39.86N 89.46W
06/29/2023                   Sangamon           IL   Trained Spotter

            Extensive tree damage in Dawson with
            numerous roads blocked by debris. Time
            estimated by radar.

1240 PM     Tstm Wnd Dmg     1 NW Taylorville        39.56N 89.31W
06/29/2023                   Christian          IL   Public

            Report from mPING: 3-inch tree limbs broken;
            Power poles broken.

1250 PM     Tstm Wnd Dmg     Heyworth                40.31N 88.98W
06/29/2023                   McLean             IL   Emergency Mngr

            Trees down.

1250 PM     Tstm Wnd Gst     Heyworth                40.31N 88.98W
06/29/2023  M60 MPH          McLean             IL   Emergency Mngr

1258 PM     Tstm Wnd Gst     Le Roy                  40.35N 88.76W
06/29/2023  E60 MPH          McLean             IL   Emergency Mngr

&&

Erwin

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