Hail and Damaging Winds in Illinois, May 7, 2016

Area Forecast Discussion
National Weather Service Lincoln IL
257 PM CDT SAT MAY 7 2016

.SHORT TERM...(Tonight)
ISSUED AT 257 PM CDT Sat May 7 2016

19z/2pm surface analysis shows cold front sagging southward toward
the I-74 corridor.  With dewpoints pooling in the upper 50s to
around 60 along/ahead of the boundary, latest LAPS data is
indicating SBCAPE values of 1000-1500J/kg.  0-6km bulk shear remains
rather weak, but is expected to increase to between 40 and 50kt
later this afternoon/evening as an upper trough digs into the Great
Lakes.  Given the moderate instability/shear parameters, the
potential exists for a few strong to severe thunderstorms from now
through about 02z/9pm.  HRRR has consistently been showing clusters
of thunderstorms developing across northern Missouri/southern Iowa
this afternoon, then tracking southeastward across mainly the
southern third of the KILX CWA.  Latest radar mosaic confirms the
HRRR, with thunderstorms currently around Quincy moving toward the
Winchester/Jacksonville areas.  Thunderstorms should track/develop
southeastward over the next few hours, impacting locations along and
south of a Rushville...to Lincoln...to Paris line through early
evening.  Main threats from the storms will be gusty winds and hail.
Once this initial wave of convection passes into the Ohio River
Valley, a lull in the precip is expected for the remainder of the
evening.  Overnight...a weak LLJ interacting with the stalled
frontal boundary will result in scattered thunderstorm development
across the entire area.  Have therefore focused highest PoPs across
the S/SE CWA late this afternoon into the early evening, then have
gone with chance PoPs across the board after midnight.

&&

.LONG TERM...(Sunday through Saturday)
ISSUED AT 257 PM CDT Sat May 7 2016

The cold front will stall out south of our forecast area in the Ohio
River Valley by Sunday morning, with spotty showers lingering in the
post-frontal airmass across central IL. A majority of the day looks
dry, but will keep slight chance PoPs in the forecast due to
channeled vorticity in the northwest flow moving across IL. Sunday
afternoon, precip chances will begin to increase for areas west of
Springfield to Shelbyville, as the front begins to make a faster
northward push west of Illinois.

The warm front will lift northward through our forecast area
starting Sunday night, reaching between I-74 and I-88 by 00z/7pm
Monday. Likely chances of rain and storms will accompany the front,
with increasing PoPs from SW to NE Sunday night and Monday. There
may be a break in the rain Monday morning, which could allow the
atmosphere to recharge in the warm sector over central IL. A few
storms may become strong in our western counties Monday
afternoon/evening west of a line from Rushville to Springfield to
Taylorville, where CAPE values could climb to 1000 J/kg depending on
if any sunshine breaks through for any amount of time. Dewpoints
will climb into the low 60s, providing added fuel for storms.

Central IL will remain in the warm sector Monday night and Tuesday,
when categorical PoPs were expanded in the forecast to cover
increasing instability params. Tuesday afternoon, MUCAPES of 2000
J/kg appear possible, with additional strong storms across the
board. Shear values look marginal, so mainly large hail with those
storms.

Another break in the storms looks possible later Tuesday night and
Wednesday, before a cold front and a line of storms push across
Illinois Wed night.

Cooler air will arrive behind that front, along with some drier air
for Thursday through Friday morning. A cold front projected to reach
central IL Friday afternoon will increase rain and storm chances
once again through Friday night.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1249 PM CDT Sat May 7 2016

Main aviation forecast concern will be convective chances this
afternoon/evening. 17z surface analysis shows cold front sinking
southward into north-central Illinois...with primary zone of
showers/isolated thunder currently along the I-74 corridor. Have
carried VCTS at KPIA/KBMI/KCMI through 22/23z accordingly. Later
in the day, the front will slip further south and convection
currently along the Iowa/Missouri border will track eastward into
portions of central Illinois. HRRR suggests this activity will
primarily impact KSPI and KDEC between 21z and 00z. After that, a
lull in the precip is expected through much of the evening before
warm-advection showers develop along the stalled frontal boundary
overnight. Forecast soundings show VFR ceilings through the entire
period. Winds will initially be from the northwest at 10-15 kt
this afternoon, then will veer to the northeast this evening,
before becoming light/variable overnight.

&&

.ILX Watches/Warnings/Advisories...
NONE.
&&

SHORT TERM...Barnes
LONG TERM...Shimon
AVIATION...Barnes

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LINCOLN IL
310 PM CDT SAT MAY 7 2016

ILZ027>031-036>038-041>046-053-055-057-081100-
CHAMPAIGN-DE WITT-DOUGLAS-EDGAR-FULTON-KNOX-LOGAN-MACON-MARSHALL-
MASON-MCLEAN-PEORIA-PIATT-STARK-TAZEWELL-VERMILION-WOODFORD-
310 PM CDT SAT MAY 7 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
ILLINOIS...EAST CENTRAL ILLINOIS...NORTH CENTRAL ILLINOIS AND
WEST CENTRAL ILLINOIS.

.DAY ONE...TONIGHT

WIDELY SCATTERED THUNDERSTORMS WILL DEVELOP TONIGHT...HOWEVER
SEVERE WEATHER IS NOT EXPECTED.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A FRONTAL BOUNDARY WILL WAVER ACROSS THE AREA FOR THE NEXT
SEVERAL DAYS.  AS A RESULT...PERIODS OF SHOWERS AND THUNDERSTORMS
ARE EXPECTED SUNDAY THROUGH WEDNESDAY. STRONG THUNDERSTORMS WILL
BE POSSIBLE AT TIMES THROUGH THE ENTIRE PERIOD...HOWEVER IT
APPEARS THE GREATEST CHANCE FOR WIDESPREAD SEVERE WEATHER MAY
DEVELOP ON TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.

ILZ040-047>052-054-056-061>063-066>068-071>073-081100-
CASS-CHRISTIAN-CLARK-CLAY-COLES-CRAWFORD-CUMBERLAND-EFFINGHAM-
JASPER-LAWRENCE-MENARD-MORGAN-MOULTRIE-RICHLAND-SANGAMON-SCHUYLER-
SCOTT-SHELBY-
310 PM CDT SAT MAY 7 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
ILLINOIS...EAST CENTRAL ILLINOIS...SOUTH CENTRAL ILLINOIS...
SOUTHEAST ILLINOIS AND WEST CENTRAL ILLINOIS.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS WILL CONTINUE THROUGH TONIGHT. A FEW OF
THE STORMS COULD BECOME STRONG TO SEVERE DURING THE EARLY
EVENING...PRIMARILY ALONG AND SOUTH OF A RUSHVILLE...TO
DECATUR...TO PARIS LINE. THE MAIN THREATS WILL BE GUSTY WINDS AND
HAIL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A FRONTAL BOUNDARY WILL WAVER ACROSS THE AREA FOR THE NEXT
SEVERAL DAYS.  AS A RESULT...PERIODS OF SHOWERS AND THUNDERSTORMS
ARE EXPECTED SUNDAY THROUGH WEDNESDAY. STRONG THUNDERSTORMS WILL
BE POSSIBLE AT TIMES THROUGH THE ENTIRE PERIOD...HOWEVER IT
APPEARS THE GREATEST CHANCE FOR WIDESPREAD SEVERE WEATHER MAY
DEVELOP ON TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THROUGH 9 PM.

BARNES