Severe Thunderstorm Warning 15, NWS Lincoln, IL

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
635 PM CDT Wed Mar 13 2024

.KEY MESSAGES...

- Unseasonably warm tonight and Thursday with temperatures more
  typical of early to mid May.

- Warm front lifting into central IL tonight, increasing coverage
  of showers and thunderstorms, with a few strong to severe storms
  carrying a hail risk.

- Slight risk of severe storms over central and southeast IL for
  Thursday afternoon and evening. All severe weather modes at play
  including large hail, damaging winds, and a few tornadoes.

- Much cooler weather after a cold frontal passage late Saturday.
  Hard freeze Sunday night and Monday night may harm any tender
  emerging vegetation.

&&

.DISCUSSION...
Issued at 206 PM CDT Wed Mar 13 2024

Unseasonable warmth continues over central and SE IL this
afternoon - 2 pm temperatures in the lower 70s. Dew points have
risen into the lower 50s over west central IL where a cumulus
field has recently developed, otherwise mid level clouds are more
prevalent farther north/east where mid/upper 40s dew points are
prevalent. Latest surface map showed 1000 mb low pressure over the
OK panhandle with a warm front stretched east into southern MO.
Aloft, water WV imagery and UA analysis showed a trough digging
through the central Rockies and lead shortwave energy already
pushing into the central Plains.

Thunderstorm activity is expected to develop near the I-70
corridor this evening ahead of the northward surging warm front,
aided by the convergent nose of a 40 kt 850-925 mb jet. The
coverage of storms should increase overnight, while lifting north,
as ascent increases ahead of a shortwave and strengthening mid
level jet streak. Thermodynamic profiles favor hail with this
elevated convection, potentially severe (1"+ diameter)
particularly west of I-57 where SPC has expanded a marginal
severe risk (level 1/5). In this area steep mid level lapse rates
will contribute to 1000+ J/kg MUCAPE, while deep layer shear
strengthens from around 25 kt at midnight to near 50 kt by
sunrise. A few convective allowing models (CAMs) develop linear
convection over northern MO after midnight, tracking east into the
western CWA around sunrise. Should this become an organized
convective system, it would carry an attendant severe threat
including damaging wind gusts if it can become surface based.

Details become somewhat murky by midday due to the previous
convection, but the overall environment will be favorable for
another round of severe weather along and ahead of a southeastward
advancing cold front. Compared to 24 hours ago, guidance shows a
faster frontal progression, possibly already bisecting the CWA
from northeast to southwest near the I-55 corridor by 00z.
Moderate instability and strong shear will make all severe modes
in play ahead of the front. Most guidance shows the severe
convection shifting southeast of our I-70 counties near or just
after midnight. SPC maintains a slight risk (level 2/5) for the
entire area Thursday afternoon/evening.

The airmass ahead of the cold front will continue to be
unseasonably warm. Tonight we are looking at lows in the mid/upper
50s, or several degrees warmer than typical highs for mid March.
Thursday will be the last in this stretch of late-spring air, with
highs mainly in the lower 70s.

Only a slight cooldown is shown behind Thursday night's cold
front (highs in the 50s to 60s Fri/Sat). However, fast northwest
flow aloft will usher a much stronger cold front across the
region Saturday afternoon or Saturday night. Blustery and cold
weather follows for Sunday and Monday. For those with early
gardening interests, a hard freeze appears likely for both Monday
and Tuesday morning. While most of the extended forecast is dry,
we'll need to watch a shortwave rotating around a Great Lakes
upper low Sunday afternoon or night, which could produce light
snow here or nearby.

25

&&

.AVIATION...  (For the 00z TAFs through 00z Thursday Evening)
Issued at 635 PM CDT Wed Mar 13 2024

A warm front lifting into the area this evening should start to
develop scattered showers and thunderstorms by 03Z-05Z, with a
more organized north-south oriented line of thunderstorms expected
to sweep across the area around 11Z-17Z. Additional isolated to
scattered thunderstorms, potentially strong to severe, are
expected to develop late Thursday afternoon, although location and
timing will be uncertain until much closer to storm development.
MVFR cigs and vsbys will be expected with any thunderstorms, as
well as widespread MVFR cigs Thursday morning from around 12Z-15Z
until 18Z-20Z. Winds generally S around 10 kts overnight, becoming
SSW 10-15 kts with gusts 20-25 kts by 15Z-18Z.

37

&&

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

Hazardous Weather Outlook
National Weather Service Lincoln IL
314 PM CDT Wed Mar 13 2024

ILZ027>031-036>038-040>044-047>054-061-142015-
Knox-Stark-Peoria-Marshall-Woodford-Fulton-Tazewell-McLean-Schuyler-
Mason-Logan-De Witt-Piatt-Cass-Menard-Scott-Morgan-Sangamon-
Christian-Macon-Moultrie-Shelby-
314 PM CDT Wed Mar 13 2024

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

.DAY ONE...Tonight.

Scattered thunderstorms are expected to move into the area during
the mid to late evening hours and continue through the night. A few
of the storms may be strong to severe, with large hail and damaging
winds the primary hazards.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Additional thunderstorms are likely to move across the area Thursday
morning. These may be strong to severe, with large hail and damaging
winds the main concerns. Another round of storms is possible in the
late afternoon and evening. Large hail, damaging wind gusts, and
isolated tornadoes will all be possible. In addition, there is a risk
for very large hail in excess of 2 inches along and south of I-72
and west of I-57.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late this evening and overnight.

Expected storm motion is toward the northeast around 30 mph.

ILZ045-046-055>057-062-063-066>068-071>073-142015-
Champaign-Vermilion-Douglas-Coles-Edgar-Cumberland-Clark-Effingham-
Jasper-Crawford-Clay-Richland-Lawrence-
314 PM CDT Wed Mar 13 2024

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

.DAY ONE...Tonight.

Scattered showers and thunderstorms are expected to move into the
area during the late evening and continue through the night. While a
few of the storms may contain hail and gusty winds, the threat of
widespread severe weather appears low at this time.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Additional thunderstorms are likely to move across the area Thursday
morning. These may be strong to severe, with large hail and damaging
winds the main concerns. Another round of storms is possible in the
late afternoon and evening. Large hail, damaging wind gusts, and
isolated tornadoes will all be possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

Deubelbeiss

Special Weather Statement
National Weather Service Lincoln IL
750 PM CDT Wed Mar 13 2024

ILZ056-061-062-140115-
Coles-Shelby-Cumberland-
750 PM CDT Wed Mar 13 2024

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN COLES...EAST
CENTRAL SHELBY AND NORTHWESTERN CUMBERLAND COUNTIES THROUGH 815 PM
CDT...

At 749 PM CDT, Doppler radar was tracking a strong thunderstorm over
Neoga, moving northeast at 15 mph.

HAZARD...Wind gusts up to 50 mph and nickel size 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...
Mattoon, Neoga, Lerna, Janesville, Paradise, Trowbridge, Etna,
Trilla, and Coles County Airport.

This includes Interstate 57 between mile markers 174 and 190.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3928 8852 3936 8855 3951 8830 3932 8819
TIME...MOT...LOC 0049Z 244DEG 15KT 3935 8847

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...50 MPH

37

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