325
FXUS63 KILX 190936
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
436 AM CDT FRI JUN 19 2026
KEY MESSAGES
- THE PROBABILITY OF HEAVY RAINFALL ON SUNDAY CONTINUES TO
STEADILY INCREASE. THE LATEST NBM HAS A 40-50% CHANCE OF 3"
OF RAIN WEST OF A JACKSONVILLE TO BLOOMINGTON LINE.
- SEVERE STORMS ARE POSSIBLE ON SUNDAY. THERE IS A SLIGHT RISK
(LEVEL 2 OF 5) ALONG AND SOUTH OF A JACKSONVILLE TO CHARLESTON
LINE, WITH A MARGINAL RISK (LEVEL 1 OF 5) TO THE NORTH.
DISCUSSION
ISSUED AT 227 AM CDT FRI JUN 19 2026
*** THROUGH SATURDAY ***
UPPER LEVEL TROUGHING PERSISTS OVER EASTERN CANADA, WITH A DEEP (SUB-
990 MB) SFC LOW JUST NORTH OF MAINE. THE ASSOCIATED COLD FRONT ARCS
SOUTHWEST, EVENTUALLY TRANSITIONING TO MORE OF A STATIONARY FRONT
OVER PORTIONS OF THE TN VALLEY AND INTO TX. CLOSER TO HOME, WEAK SFC
HIGH PRESSURE PERSISTS, AND BOTH TEMPS AND DEWPOINTS NORTH OF THE
FRONT WILL BE SEASONABLY COOL, WITH HIGHS TODAY NEAR 80F AND
DEWPOINTS IN THE UPPER 50S.
THE NW FLOW REGIME WILL RESULT IN MULTIPLE EMBEDDED WAVES
APPROACHING THE REGION OVER THE COMING DAYS. WHILE MUCH OF THE
ATTENTION REMAINS ON SUNDAY'S SYSTEM, THERE WILL BE A WEAKER WAVE
THAT OFFERS A CHANCE FOR SHOWERS (20-40%) NORTH OF I-72/DANVILLE,
PRIMARILY BETWEEN MIDNIGHT AND 7AM SATURDAY. MOST AREAS SHOULD
RECEIVE LESS THAN 0.25" OF RAIN FROM THESE SHOWERS.
*** SUNDAY EXCESSIVE RAINFALL POTENTIAL ***
THE TRACK OF SUNDAY'S SFC LOW CONTINUES TO BE A STICKING POINT FOR
THE FORECAST. ENSEMBLE MEMBER LOW LOCATIONS ARE GENERALLY FOCUSED
SOMEWHERE BETWEEN I-70 AND I-80, ALTHOUGH THERE REMAIN OUTLIER LOW
TRACKS ACROSS FAR SOUTHERN OR FAR NORTHERN IL. EVEN THE DIFFERENCE
BETWEEN A LOW TRACK NEAR I-70 VS I-80 WILL HAVE LARGE IMPLICATIONS
ON THE FORECAST FOR THE ILX CWA. A MORE NORTHERLY TRACK INCREASES
THE SEVERE RISK BUT PERHAPS KEEPS THE GREATEST FLOOD RISK TO OUR
NORTH, WHILE A SOUTHERLY TRACK OFFERS THE INVERSE.
DESPITE THE TRACK UNCERTAINTY, THE PROBABILITY OF EXCESSIVE RAINFALL
DOES CONTINUE TO STEADILY INCREASE. ENSEMBLE MEAN PWATS ARE IN
EXCESS OF 2", WHICH IS NEAR THE 99TH PERCENTILE OF THE MODEL
CLIMATOLOGY. LATEST PROBABILISTIC GUIDANCE FROM THE NBM HAS A 50-70%
CHANCE OF MORE THAN 2" OF RAIN NORTH OF I-70 (UP FROM 40-60% IN THE
PREVIOUS ITERATION), AND A 40-50% CHANCE OF EXCEEDING 3" OF
RAIN WEST OF A BLOOMINGTON-JACKSONVILLE LINE. A FLOOD WATCH MAY
EVENTUALLY BE NEEDED AS THE EXACT CORRIDOR OF THE HEAVIEST
RAINFALL BECOMES CLEARER.
*** SUNDAY SEVERE STORM POTENTIAL ***
IN TERMS OF SEVERE STORMS, IT IS AN UNUSUAL SETUP FOR JUNE AS
INSTABILITY, NOT WIND SHEAR, IS THE MOST QUESTIONABLE INGREDIENT.
THE WIND SHEAR ON SUNDAY WON'T BE AS STRONG AS WHAT WE WITNESSED ON
WED JUNE 17, BUT STILL QUITE UNSEASONABLE FOR JUNE. 850MB WINDS ARE
FORECAST TO EXCEED 40 KTS, WHICH IS ABOVE THE 95TH PERCENTILE OF THE
MODEL CLIMATOLOGY. THERE REMAINS A LARGE SPREAD IN THE FORECAST
SURFACE-BASED INSTABILITY VALUES, WITH SOME GUIDANCE SHOWING LITTLE
TO NONE AND OTHERS EXCEEDING 1500 J/KG. THE AMOUNT AND TYPE (SURFACE-
BASED VS ELEVATED) OF INSTABILITY WILL ULTIMATELY MODULATE THE
SEVERE RISK AND ASSOCIATED HAZARD TYPES FOR SUN, BUT GIVEN THESE
SHEAR PROFILES AND MOST ENSEMBLE MEMBERS SHOWING AT LEAST MARGINAL
INSTABILITY, THINK AT LEAST SOME SEVERE THREAT WILL MATERIALIZE,
UNLESS THE ACTUAL LOW TRACK IS ALONG THE SOUTHERN FRINGES OF THE
CURRENT ENSEMBLE ENVELOPE.
BACKED SFC WINDS ARE POSSIBLE IN THE WARM SECTOR AHEAD OF THE
SFC LOW AS WELL AS ALONG A POTENTIAL WARM FRONT, WHICH WOULD BE
DRAPED EAST OR EAST-NORTHEAST AHEAD OF THE SFC LOW. THE LOW IS
EXPECTED TO MOVE ACROSS IL AT A FAVORABLE DIURNAL TIMING TO
MAXIMIZE WHATEVER SFC-BASED INSTABILITY DOES DEVELOP. A TORNADO
THREAT COULD MATERIALIZE, AND WOULD BE MOST LIKELY IN AREAS
WHERE BOTH SFC-BASED INSTABILITY AND BACKED SFC WINDS DEVELOP.
WIND IS THE TOP CONCERN, OWING TO THE POTENTIAL FOR
PRECIPITATION LOADING. THE HIGH PWAT ENVIRONMENT LIMITS MID-
LEVEL LAPSE RATES, LOWERING THE HAIL THREAT.
*** INTO NEXT WEEK ***
THIS SYSTEM WILL DEPART ON MON, WITH LINGERING PRECIP EXITING TO THE
EAST. ANOTHER WEAK SFC HIGH PRESSURE SHOULD RESULT IN DRY CONDITIONS
TUES, THEN ANOTHER SERIES OF DISTURBANCES TRACK NORTH OF THE AREA
AND REINTRODUCE PRECIP CHANCES WED-ONWARD. TEMPS ARE FORECAST TO
REMAIN BELOW NORMAL NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
ISSUED AT 434 AM CDT FRI JUN 19 2026
VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE PERIOD, WITH
LIGHT NORTHWESTERLY WINDS DURING THE DAY. A NARROW LINE OF
SHOWERS WILL SHIFT SOUTH INTO THE AREA LATE IN THE PERIOD. A
PROB30 FOR SHOWERS WAS INCLUDED AT KPIA/KBMI, BEGINNING AROUND
06-07Z. THE THUNDER POTENTIAL WITH THESE SHOWERS IS LOW, BUT
NOT ZERO.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...ERWIN
DISCUSSION...ERWIN
AVIATION...ERWIN
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