450
FXUS63 KILX 180335
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1035 PM CDT WED JUN 17 2026
KEY MESSAGES
- A TORNADO WATCH IS IN EFFECT UNTIL 10PM CDT FOR LOCATIONS
ALONG AND SOUTH OF A MACOMB TO CHENOA LINE. ALL SEVERE HAZARDS
ARE POSSIBLE...WITH THE GREATEST PROBABILITY FOR STRONG
TORNADOES FOCUSING SOUTH OF A SPRINGFIELD TO PARIS LINE.
- QUIET WEATHER WILL PREVAIL THURSDAY THROUGH SATURDAY...WITH
THE NEXT CHANCE FOR THUNDERSTORMS ARRIVING BY SUNDAY.
DISCUSSION
ISSUED AT 316 PM CDT WED JUN 17 2026
19Z/2PM MESOANALYSIS SHOWS AN OUTFLOW BOUNDARY LEFT BEHIND BY
THE MORNING CONVECTION ALONG A QUINCY...TO LITCHFIELD...TO
SALEM LINE. THIS IS CONSIDERABLY FURTHER SOUTH THAN PREVIOUSLY
THOUGHT: THEREFORE THE MOST SIGNIFICANT RISK FOR WIDESPREAD
SEVERE WEATHER LATER THIS AFTERNOON AND EVENING HAS SHIFTED
SOUTH AS WELL. AS SUCH, THE NEW TORNADO WATCH COORDINATED WITH
SPC DOES NOT INCLUDE THE FAR NORTHERN KILX CWA FROM THE PEORIA
AREA NORTHWARD.
MLCAPES ARE CURRENTLY UNDER 1000J/KG: HOWEVER, AS THE BOUNDARY
MIXES SLOWLY NORTHWARD THIS AFTERNOON, THE RAP SUGGESTS MLCAPES
WILL INCREASE INTO THE 1500-2000J/KG ALONG/SOUTHEAST OF A QUINCY
TO CHAMPAIGN LINE OVER THE NEXT COUPLE OF HOURS. IMPRESSIVE WIND
FIELDS ALOFT ARE CONTRIBUTING TO VERY STRONG 0-6KM BULK SHEAR
OF 60-80KT...WHILE 0-1KM SHEAR VALUES REMAIN IN THE 30-40KT
RANGE. GIVEN MARGINAL INSTABILITY AND EXTREME SHEAR, AM
EXPECTING SUPERCELL THUNDERSTORMS TO RAPIDLY DEVELOP ALONG/AHEAD
OF A SLOWLY ADVANCING COLD FRONT ACROSS THE ILLINOIS RIVER
VALLEY IMMINENTLY. ALL SEVERE HAZARDS WILL BE IN PLAY...INCLUDING
DAMAGING WIND GUSTS IN EXCESS OF 70MPH, HAIL LARGER THAN
GOLF BALLS, AND TORNADOES. THE SIGNIFICANT TORNADO PARAMETER
(STP) IS CURRENTLY MAXIMIZED CLOSER TO THE OUTFLOW BOUNDARY
FROM CENTRAL/NORTHERN MISSOURI ACROSS SOUTH-CENTRAL ILLINOIS,
BUT IS PROGGED TO LIFT NORTHWARD LATER THIS AFTERNOON/EVENING.
AT THIS TIME, IT APPEARS THE HIGHEST PROBABILITY OF POTENTIALLY
STRONG TORNADOES WILL FOCUS ALONG/SOUTH OF A SPRINGFIELD TO
PARIS LINE.
THUNDERSTORMS ARE CURRENTLY DEVELOPING IN A BAND FROM
GALESBURG/RUSHVILLE EASTWARD TO PONTIAC/CHAMPAIGN. CAMS HAVE
GENERALLY SPED UP THE DEVELOPMENT PROCESS, AS WELL AS THE
GRADUAL S/SE MOVEMENT OF THE BAND. AS A RESULT, THINK THE
PRIMARY SEVERE RISK WILL BE FOCUSED ALONG THE I-72 CORRIDOR
BETWEEN 4PM AND 6PM, THEN WILL SINK TOWARD I-70 BY 7PM TO 9PM.
THE PRIMARY LINE OF CONVECTION WILL EXIT THE FAR SE KILX CWA
AROUND MIDNIGHT: HOWEVER, A FEW SHOWERS MAY LINGER FURTHER NORTH
THROUGHOUT THE EVENING INTO THE FIRST PART OF THE OVERNIGHT.
A SHORT-WAVE TROUGH WILL BRING A PERIOD OF MID-LEVEL CLOUDINESS
TO CENTRAL ILLINOIS THURSDAY MORNING, WITH FORECAST SOUNDINGS
SUGGESTING THE POTENTIAL FOR A FEW LIGHT RAIN SHOWERS MOSTLY
ALONG/SOUTH OF A RUSHVILLE TO ROBINSON LINE WHERE SLIGHT CHANCE
POPS (20%) ARE WARRANTED. ONCE THIS WAVE DEPARTS, A RETURN TO
COOL AND MOSTLY DRY WEATHER WILL BE ON TAP FOR FRIDAY AND
SATURDAY. THE NEXT SIGNIFICANT CHANCE FOR PRECIPITATION WILL
HOLD OFF UNTIL LATE SATURDAY NIGHT INTO SUNDAY AS A STRONGER
SHORT-WAVE TROUGH TRAVERSES THE PLAINS AND APPROACHES FROM THE
WEST. GIVEN BETTER DEEP-LAYER MOISTURE AND STRONG FORCING, THINK
SHOWERS AND THUNDERSTORMS WILL BECOME WIDESPREAD. THE SEVERE
WEATHER RISK REMAINS UNCERTAIN AT THIS TIME, WITH SEVERAL
MACHINE LEARNING ALGORITHMS SUCH AS COLORADO STATE AND NSSL
KEEPING THE GREATEST PROBABILITIES FURTHER SOUTH. A FEW NCAR
MEMBERS DO HOWEVER SUGGEST 15-30% PROBS NORTHWARD INTO CENTRAL
ILLINOIS, SO WILL NEED TO KEEP AN EYE ON MESOSCALE DETAILS AS
THE TIME NEARS.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1035 PM CDT WED JUN 17 2026
QUIET WEATHER WITH VFR CONDITIONS ARE EXPECTED FOR THE 06Z TAF
PACKAGE. EARLIER CONVECTION HAS CLEARED THE TERMINALS AS A COLD
FRONT SLOWLY MOVES INTO THE REGION FROM THE N/NW. WINDS WILL BE
STEADY FROM W OVERNIGHT AROUND 8-12 KTS, SHIFTING TO THE
NORTHWEST AFTER 13-16Z AND INCREASE TO 10-15 KTS. LINGERING
DEBRIS CU AROUND SPI, DEC, AND CMI WILL CLEAR OUT BY 8-10Z,
FOLLOWED BY DIURNAL CU DEVELOPING AFTER 13-15Z WITH BASES AROUND
5-7KFT. FRIDAY NIGHT, SKIES WILL CLEAR WITH WINDS RELAXING TO
TO 4-7 KTS FROM THE NW.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...BARNES
DISCUSSION...BARNES
AVIATION...WFO PAH
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