891
FXUS63 KILX 212307
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
607 PM CDT TUE JUL 21 2026
KEY MESSAGES
- PLEASANT MID-WEEK WEATHER: EXPECT CALM WEATHER WITH BELOW-
NORMAL TEMPERATURES WEDNESDAY AND THURSDAY, WITH AFTERNOON
HIGHS REMAINING IN THE MID-TO-UPPER 70S.
- HEAT RETURNS THIS WEEKEND: HIGH TEMPERATURES REBOUND INTO THE 90S
BY SUNDAY AND MONDAY. THERE IS A 20% CHANCE OF PERIODIC
THUNDERSTORMS RETURNING LATE FRIDAY INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 1219 PM CDT TUE JUL 21 2026
NEAR TERM FORECAST...
THE CURRENT SURFACE ANALYSIS PLACES A COLD FRONT ALONG THE I-70
CORRIDOR, WITH EXPECTED PROGRESSION SOUTHEASTWARD AND OUT OF
OUR CWA BY MID-AFTERNOON. RAP ANALYSIS CONTINUES TO HIGHLIGHT AN
UNSTABLE AIRMASS AHEAD OF THE BOUNDARY, CHARACTERIZED BY MLCAPE
VALUES NEAR 3000 J/KG AND DEEP-LAYER SHEAR PROFILES OF 30-40
KT. GIVEN THIS OVERLAP, A BRIEF WINDOW OF OPPORTUNITY FOR SEVERE
THUNDERSTORM DEVELOPMENT EXISTS THROUGH MID AFTERNOON BEFORE
THE FRONT EXITS THE REGION. BEHIND THE BOUNDARY, A COOLER AND
DRIER AIR MASS IS FILTERING INTO THE REGION ON GUSTY NORTHWEST
WINDS. DEW POINTS HAVE ALREADY BEGUN A DOWNWARD TREND,
EVENTUALLY BOTTOMING OUT IN THE 50S ACROSS THE NORTHERN TIER OF
THE FORECAST AREA TONIGHT, WITH AMBIENT TEMPERATURES SETTLING
INTO THE 60S UNDER MOSTLY CLEAR SKIES.
WEDNESDAY THROUGH FRIDAY...
THE MIDDLE OF THE WEEK WILL FEATURE A TRANSITION TO A MORE
TRANQUIL REGIME AS A ROBUST CANADIAN HIGH-PRESSURE SYSTEM
BUILDS SOUTHEAST ACROSS THE MIDWEST. THIS WILL FACILITATE A
TREND TOWARD BELOW-NORMAL TEMPERATURES, WITH AFTERNOON HIGHS
CONFINED TO THE MID TO UPPER 70S. DRY CONDITIONS ARE ANTICIPATED
TO PREVAIL THROUGH THURSDAY NIGHT. BY FRIDAY, GUIDANCE SUGGESTS
THE POTENTIAL FOR WARM AIR ADVECTION-DRIVEN CONVECTION
ORIGINATING TO OUR WEST. WHILE CONFIDENCE REMAINS LOW, THERE IS
A NON-ZERO POTENTIAL FOR THESE SHOWERS AND THUNDERSTORMS TO
ENCROACH UPON PORTIONS OF CENTRAL ILLINOIS; HOWEVER, THE LACK OF
SIGNIFICANT MOISTURE RETURN CURRENTLY LIMITS MORE ROBUST POP
INCLUSION.
THIS WEEKEND INTO NEXT WEEK...
AS THE SURFACE RIDGE TRANSLATES TOWARD THE ATLANTIC COAST OVER
THE WEEKEND, THE RETURN OF LOW-LEVEL SOUTHERLY FLOW WILL
INITIATE A NOTICEABLE WARMING TREND. TEMPERATURES ARE PROGGED TO
REBOUND SIGNIFICANTLY, WITH WIDESPREAD 90S RETURNING TO THE
FORECAST BY SUNDAY AND MONDAY. THE SYNOPTIC PATTERN REMAINS
ANCHORED BY NORTHWEST FLOW ALOFT, WITH PERIODIC, LOWER-AMPLITUDE
SHORTWAVES EXPECTED TO TRAVERSE THE REGION. THESE DISTURBANCES
MAY SERVE AS CATALYSTS FOR CONVECTIVE INITIATION, THOUGH TIMING
AND PLACEMENT REMAIN DIFFICULT TO RESOLVE THIS FAR OUT. HAVE
CAPPED PRECIPITATION CHANCES AT APPROXIMATELY 20% DURING THIS
TIMEFRAME UNTIL BETTER AGREEMENT IS REACHED AMONG SHORT-RANGE
GUIDANCE.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 607 PM CDT TUE JUL 21 2026
AFTER THE SMOKE AND HAZE OF THE LAST COUPLE DAYS, VFR CONDITIONS
WILL PREVAIL THE NEXT 24 HOURS, WITH GOOD VISIBILITY. SCATTERED
DIURNAL CLOUDS WILL FADE WITH SUNSET, THOUGH A FEED OF MOISTURE
OFF LAKE MICHIGAN WILL KEEP A SCATTERED DECK NEAR 4-5KT OVER
EASTERN ILLINOIS. GUSTY NORTHWEST WINDS WILL SUBSIDE A BIT AND
TREND TOWARD THE NORTHEAST LATE THIS EVENING, WITH THE LAKE
BREEZE PERSISTING INTO LATE WEDNESDAY MORNING.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...DEUBELBEISS
DISCUSSION...DEUBELBEISS
AVIATION...GEELHART
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