Severe Thunderstorm Warning 159, NWS Lincoln, IL

Area Forecast Discussion...Updated
National Weather Service Lincoln IL
1103 AM CDT Thu Jun 29 2023

.SYNOPSIS...
Issued at 1044 AM CDT Thu Jun 29 2023

Another round of severe thunderstorms are expected to track
eastward over central and southeast IL through the 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. 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 Friday and this weekend with more rounds of showers
and thunderstorms.

&&

.UPDATE...
Issued at 1050 AM CDT Thu Jun 29 2023

Updated the forecast a couple times this morning, 1st with ending
the severe thunderstorm watch over eastern IL at 9 am, and again
late this morning with a new severe thunderstorm watch for all of
central and southeast IL through 5 pm today.

1st batch of storms with MCS was still affecting the Wabash river
valley in far southeast IL though the stronger cells are east/se
of Clark, Crawford and Lawrence counties. These storms produce 1-2
inch hail since overnight in eastern IL and even 3.25 inch hail
in Tuscola around 650 pm. Also had reports of 1.5-2.5 inch rains
in spots over eastern IL. Focus shifts to developing area of
strong to severe convection with next MCS over southeast
IA/northeast MO and approaching west central IL. SPC just issued
a severe thunderstorm watch for a large portion of IL through
22z/5 pm with widespread damaging wind gusts of 60 to 80 mph
possible, scattered large hail (1 inch or larger) and isolated
very large hail of golf ball to 3 inches possible. Isolated
tornados also risk along with locally heavy rains as tropical PW
values are 1.75-2.2 inches, highest over southern/sw CWA. Strong
effective bulk shear values of 35-55 kts while  very unstable air
mass with SB CAPES peaking from 3000-6000 j/kg and MLCapes of
2500-4500 j/kg, highest in southern/sw CWA. The eastern edge of
storms is just west of Schuyler county and CAMs bring line of
storms quickly eastward toward I-55 at or just after 18Z/1 pm and
to Indiana border by 20-21Z/3-4 pm. Temps climbing into the mid to
upper 80s in western CWA ahead of storms and rest of CWA should
see highs reach similar values or even near 90F in sw CWA before
storms race through and cool temps back down.

Continued air quality alert through 7 pm as worst air quality
currently is northern and ne CWA where Unhealthy conditions (red
color) and much of CWA has unhealthy for sensitive groups (orange
color). But smoke/hazy conditions should improve following
passage of squall line and air quality alert may be able to end
early.

07

&&

.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 12z TAFs through 12z Friday Morning)
Issued at 558 AM CDT Thu Jun 29 2023

MVFR conditions will continue for a few more hours with lower
visibilities due to smoke and haze, with a substantial improvement
expected by 12Z at all TAF sites. By 12Z, VFR conditions
should prevail.

There are multiple round of thunderstorms expected today, one
currently ongoing from KPIA-KDEC east more scattered in nature. The
second round is expected early afternoon and is more likely to be
severe, with wind gusts above 30 knots and brief MVFR/IFR conditions
due to heavy rain and ceilings.

Delaney

&&

.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
942 AM CDT Thu Jun 29 2023

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

0920 AM     Rain             5 NW Oliver             39.54N 87.75W
06/29/2023  M2.39 inch       Edgar              IL   Cocorahs

&&

Erwin

Special Weather Statement
National Weather Service Lincoln IL
952 AM CDT Thu Jun 29 2023

ILZ056-291515-
Coles-
952 AM CDT Thu Jun 29 2023

...A strong thunderstorm will impact portions of central Coles County
through 1015 AM CDT...

At 952 AM CDT, Doppler radar was tracking a strong thunderstorm over
Humboldt, or 7 miles north of Mattoon, moving southeast at 25 mph.

HAZARD...Winds in excess of 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This strong thunderstorm will be near...
  Mattoon around 955 AM CDT.

Other locations in the path of this storm include Charleston.

This includes Interstate 57 between mile markers 189 and 201.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3956 8845 3965 8842 3965 8808 3941 8824
TIME...MOT...LOC 1452Z 296DEG 24KT 3958 8835

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

37

Special Weather Statement
National Weather Service Lincoln IL
1015 AM CDT Thu Jun 29 2023

ILZ063-291530-
Clark-
1015 AM CDT Thu Jun 29 2023

...A strong thunderstorm will impact portions of central Clark County
through 1030 AM CDT...

At 1014 AM CDT, Doppler radar was tracking a strong thunderstorm over
Martinsville, or 13 miles west of Marshall, moving southeast at 30
mph.

HAZARD...Winds in excess of 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of central Clark
County, including the following locations... Lincoln Trail State
Park, Darwin and Orange.

This includes Interstate 70 between mile markers 128 and 140.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3931 8762 3930 8761 3930 8760 3927 8761
      3918 8769 3919 8789 3924 8800 3938 8801
      3945 8796 3933 8759
TIME...MOT...LOC 1514Z 301DEG 28KT 3934 8793

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

37

Special Weather Statement
National Weather Service Lincoln IL
1029 AM CDT Thu Jun 29 2023

ILZ063-291545-
Clark-
1029 AM CDT Thu Jun 29 2023

...A strong thunderstorm will impact portions of southeastern Clark
County through 1045 AM CDT...

At 1029 AM CDT, Doppler radar was tracking a strong thunderstorm over
West Union, or 12 miles south of Marshall, moving east at 25 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

This storm will remain over mainly rural areas of southeastern Clark
County, including the following locations... Darwin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3918 8761 3919 8762 3917 8762 3919 8777
      3930 8774 3929 8760 3928 8761 3927 8760
      3926 8761 3925 8759 3925 8757 3922 8757
TIME...MOT...LOC 1529Z 285DEG 20KT 3922 8766

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

37

Preliminary Local Storm Report
National Weather Service Lincoln IL
1044 AM CDT Thu Jun 29 2023

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

0700 AM     Rain             Palestine               39.00N 87.61W
06/29/2023  M1.53 inch       Crawford           IL   Cocorahs

1011 AM     Rain             3 W Robinson            39.01N 87.80W
06/29/2023  M1.20 inch       Crawford           IL   Mesonet

            SWOP report.

&&

Erwin

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