Severe Thunderstorm Warning 177, NWS Lincoln, IL

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
648 AM CDT Tue Jul 30 2024

.KEY MESSAGES...

- A Dense Fog Advisory remains in effect for portions of central
  Illinois until 8 am.

- A slight risk (level 2 of 5) for severe storms exists across
  most of the area for this afternoon into evening, with
  additional chances for severe storms on both Wednesday and
  Thursday.

- Heat and humidity continues across the area through Thursday
  with daily heat indices ranging from 100-110 each day.

&&

.DISCUSSION...
Issued at 343 AM CDT Tue Jul 30 2024

Light winds, recent rain, and clear skies have resulted in patchy
fog across the area early this morning. HREF probabilities for one-
quarter mile visibility or less are highest from roughly Beardstown
to near Champaign, which is roughly where the lowest visibilities
are as of 3 am. A Dense Fog Advisory is in effect for these areas
until 8 am.

594 dm mid-level ridge remains positioned over the Plains states
with northwest flow in place further east over the Midwest states.
This will open the door for several mid-level shortwaves/mesoscale
features to slide southeast across the area the next several days,
bringing daily chances for storms. There remains quite a bit of
uncertainty in storm timing for today, but the general idea is for a
remnant boundary or MCV from storms over central Iowa to be the
trigger for new development sometime later today. Very warm/humid
conditions will bring strong instability in excess of 2500 J/kg by
this afternoon paired with moderately strong mid-level flow, which
will be more than enough to support storm organization. Primary
hazards with storms will be damaging winds gusts, with SPC
introducing a hatched area for the potential of significant wind
gusts (75 mph). Orthogonal shear vectors to the orientation of the
thunderstorm complex could bring a low threat for a few tornadoes as
well. Heavy rain will also be a threat with PWATs of 1.77 to 2
inches aiding in high rainfall rates.

Heat and humidity ramp up today and persist through Thursday. High
temperatures today will climb into the upper 80s to low 90s with
heat indices of 100 to 105. However, if storms develop earlier in
the day, cloud cover and precipitation will hold these values down.
Since the potential for dangerous heat indices does exist, elected
to issue a Heat Advisory for counties along and south of a
Beardstown to Robinson line. Heat indices ranging from 105 to 110
will are likely across the entire area on both Wednesday and
Thursday, but once again storm timing will drive the need for heat
headlines in coming days.

Additional chances for storms, including severe storms, will be seen
on both Wednesday and Thursday with the higher threat (slight risk)
being on Thursday as a stronger mid-level wave brings better
forcing. Wednesday morning could start out stormy with CAMs
suggesting activity blossoming on the nose of a 40 kt LLJ over
eastern Iowa and spilling east-southeastward into Illinois.
Additional clusters could move through both late Wednesday night
into Thursday morning and Thursday evening. Some storms may fester
into Friday until the upper low pushes east of here, but the
severe threat should be minimal by that time.

High pressure settles into the Midwest states by the weekend,
bringing a period of mostly dry and more seasonable temperatures.
Oppressive dewpoints will be slow to retreat back southward until
a secondary cold front brings some relief from that early next
week.

NMA

&&

.AVIATION...  (For the 12z TAFs through 12z Wednesday Morning)
Issued at 648 AM CDT Tue Jul 30 2024

Fog is present in spots this morning with visibilities as low as
1/4 mile. Conditions should improve from the fog around or shortly
after 13Z, but may fall again with a line of storms approaching
from the west.

A challenging, low confidence forecast exists over the next 24 hours
with a few rounds of storms possible. The first round is
currently working into west-central Illinois, but is not being
resolved by any high resolution guidance. Due to its current
strength and coverage, it should hold together and reach western
TAF sites here between 12-14Z. Another round of storms is expected
to move through this afternoon into evening. Handled the second
round with PROB30 groups, though this will likely need further
refinement. Additional storms may occur late tonight into early
Wednesday morning, but placement and timing of such activity is
very uncertain.

Winds will generally hold a southwest or southerly component through
the TAF period, though a switch to west/northwest within any storms
is warranted.

NMA

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 8 AM CDT this morning for ILZ029-031-
036>038-040>053.

Heat Advisory from 1 PM this afternoon to 8 PM CDT this evening
for ILZ040-047>052-061-066>068-071>073.

&&

Hazardous Weather Outlook
National Weather Service Lincoln IL
543 AM CDT Tue Jul 30 2024

ILZ027>031-036>038-311100-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-
543 AM CDT Tue Jul 30 2024

This Hazardous Weather Outlook is for central Illinois.

.DAY ONE...Today and tonight.

Strong to severe thunderstorms will move into the area this morning
before weakening. Additional strong to severe storms are a risk this
afternoon and night as well. Damaging winds are the main concern,
with potential for wind gusts over 70 mph, though there is also a low
tornado probability.

Outside of the storms, the heat index will reach around 100 degrees,
highest south of I-74.

Patchy dense fog will occur early this morning, but will quickly lift
after sunrise.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Additional strong to locally severe storms are expected Wednesday and
Thursday. While some storms will linger into Friday, those are not
expected to be severe.

The heat index will reach 105 to 115 degrees both Wednesday and
Thursday afternoons.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through mid morning, then again this
afternoon and evening.

Expected storm motion is toward the southeast around 45 mph.

ILZ040>042-047>052-311100-
Schuyler-Mason-Logan-Cass-Menard-Scott-Morgan-Sangamon-Christian-
543 AM CDT Tue Jul 30 2024

This Hazardous Weather Outlook is for central Illinois and west
central Illinois.

.DAY ONE...Today and tonight.

Strong to severe thunderstorms will move into the area this morning
before weakening. Additional strong to severe storms are a risk this
afternoon and night as well. Damaging winds are the main concern,
with potential for wind gusts over 70 mph, though there is also a low
tornado probability.

Outside of the storms, the heat index will reach around 105 degrees.

Areas of dense fog will occur early this morning, but will quickly
lift after sunrise.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Additional strong to locally severe storms are expected Wednesday and
Thursday. While some storms will linger into Friday, those are not
expected to be severe.

The heat index will reach 105 to 110 degrees both Wednesday and
Thursday afternoons.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through mid morning, then again this
afternoon and evening.

Expected storm motion is toward the southeast around 45 mph.

ILZ043>046-053>057-061-311100-
De Witt-Piatt-Champaign-Vermilion-Macon-Moultrie-Douglas-Coles-Edgar-
Shelby-
543 AM CDT Tue Jul 30 2024

This Hazardous Weather Outlook is for east central Illinois.

.DAY ONE...Today and tonight.

Thunderstorms are expected to develop this afternoon, with a risk
continuing into tonight. These will be strong to severe, with
damaging winds the main concern.

The heat index is expected to reach the 100 degree range this
afternoon.

Areas of dense fog will continue early this morning, but will rapidly
lift after sunrise.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Additional strong to locally severe storms will linger into Wednesday
morning, though more are expected to move in later Wednesday night
and continue into Thursday. While some storms will linger into
Friday, those are not expected to be severe.

The heat index will reach 105 to 110 degrees both Wednesday and
Thursday afternoons.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

Expected storm motion is toward the southeast around 45 mph.

ILZ062-063-066>068-071>073-311100-
Cumberland-Clark-Effingham-Jasper-Crawford-Clay-Richland-Lawrence-
543 AM CDT Tue Jul 30 2024

This Hazardous Weather Outlook is for southeast Illinois.

.DAY ONE...Today and tonight.

Strong to severe thunderstorms are expected to move into the area by
late afternoon, and remain a threat into the evening. Damaging winds,
potentially higher than 70 mph, are the main concern.

Before the storms arrive, the heat index is expected to reach the 100
to 105 degree range.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

While isolated storms are possible Wednesday night, better chances
will be on Thursday. These may be strong to severe. While some
storms will linger into Friday, those are not expected to be severe.

The heat index will reach 105 to 110 degrees both Wednesday and
Thursday afternoons.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and evening.

Expected storm motion is toward the southeast around 45 mph.

Geelhart

Preliminary Local Storm Report
National Weather Service Lincoln IL
706 AM CDT Tue Jul 30 2024

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

0634 AM     Tstm Wnd Gst     Marietta                40.50N 90.39W
07/30/2024  E60 MPH          Fulton             IL   Emergency Mngr

            Estimated 50-60 mph winds around Marietta.

&&

BMD

Special Weather Statement
National Weather Service Lincoln IL
730 AM CDT Tue Jul 30 2024

ILZ048-050>052-301315-
Sangamon-Morgan-Menard-Christian-
730 AM CDT Tue Jul 30 2024

...STRONG THUNDERSTORMS WILL IMPACT SOUTHEASTERN MENARD...
NORTHWESTERN CHRISTIAN...SANGAMON AND SOUTHEASTERN MORGAN COUNTIES
THROUGH 815 AM CDT...

At 729 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Petersburg to near Franklin. Movement was
southeast at 45 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Springfield, Petersburg, Athens, Chatham, Alexander, Auburn, Sherman,
Rochester, Riverton, Pawnee, Kincaid, Williamsville, New Berlin,
Waverly, Divernon, Edinburg, Illiopolis, Pleasant Plains, Loami, and
Franklin.

This includes the following highways...
 Interstate 55 between mile markers 77 and 109.
 Interstate 72 between mile markers 76 and 123.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Lincoln.

A Severe Thunderstorm Watch remains in effect until 1000 AM CDT for
central and west central Illinois.

&&

LAT...LON 4004 8984 3987 8922 3939 8953 3952 8954
      3952 9011 3955 9018
TIME...MOT...LOC 1229Z 293DEG 39KT 3998 8980 3960 9008

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Geelhart

Preliminary Local Storm Report
National Weather Service Lincoln IL
817 AM CDT Tue Jul 30 2024

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

0746 AM     Tstm Wnd Dmg     3 NNE Springfield       39.83N 89.61W
07/30/2024                   Sangamon           IL   Trained Spotter

            Multiple 2" diameter tree branches down at
            intersection of Piper Rd and Vincent St. One
            4-6" diameter branch down on West St...just
            south of Vincent St.

&&