840
FXUS63 KDVN 271721
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1221 PM CDT MON JUL 27 2026
KEY MESSAGES
- OPPRESSIVELY HOT AND HUMID THROUGH THIS EVENING, WITH HEAT
INDICES IN MANY LOCATIONS PEAKING AROUND 105-115 DEGREES.
- THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON INTO THIS EVENING,
THOUGH THERE REMAINS SOME UNCERTAINTY DUE TO POTENTIAL
CAPPING. SOME OF THESE STORMS MAY BE STRONG TO SEVERE WITH
DAMAGING WINDS IF WELL- ORGANIZED. AN ENHANCED (LEVEL 3 OF 5)
RISK OF SEVERE THUNDERSTORMS IS IN EFFECT FOR NORTHWEST
ILLINOIS.
- SOME MIDWEEK RELIEF COMES BEHIND A COLD FRONT TONIGHT,
ALTHOUGH SMOKE FROM NORTHWEST U.S. AND CANADIAN FIRES MAY
SPREAD OVER THE AREA THAT COULD CONTINUE THROUGH TUESDAY.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 301 AM CDT MON JUL 27 2026
A COMPLICATED FORECAST IS IN STORE FOR MONDAY, BUT AMIDST THE MANY
DIFFERENT WAYS TODAY COULD PLAY OUT, THERE IS ONE CONSISTENT FACTOR:
IT WILL BE OPPRESSIVELY HOT AND HUMID. EARLY MORNING
TEMPERATURES REMAIN QUITE WARM IN THE UPPER 70S TO LOW 80S, WITH
DEW POINTS NOT FAR BEHIND. COMBINED WITH WEAK SURFACE WINDS,
THIS WARM AND HUMID AIRMASS HAS ALLOWED FOR THE DEVELOPMENT OF
PATCHY AREAS OF FOG AND LOW STRATUS NORTH OF INTERSTATE 80. THIS
ALSO INCLUDES AREAS OF DENSE FOG EAST OF THE QUAD CITIES METRO.
DIURNAL HEATING AND QUICKLY INCREASING TEMPERATURES WILL ALLOW
ANY FOG TO BURN OFF BY MID-MORNING.
ONCE THE FOG CLEARS OUT, THE SURFACE WILL QUICKLY HEAT UP, LEADING
TO YET ANOTHER OPPRESSIVELY HOT AND HUMID DAY. HIGHS ARE FORECAST IN
THE LOW TO MID 90S, WITH SOME AREAS IN THE FAR SOUTH REACHING
INTO THE UPPER 90S. DEW POINTS ARE ONCE AGAIN EXPECTED TO REACH
INTO THE LOWER 80S TODAY, LEADING TO HEAT INDICES AS HIGH AS
105 TO 115 DEGREES. AN EXTREME HEAT WARNING IS IN EFFECT AREA-
WIDE. HOWEVER, THERE IS A POTENTIAL LIMITER IN HOW HOT WE CAN
GET TODAY: THUNDERSTORMS.
GUIDANCE REMAINS KEEN ON A POTENTIAL MCS MOVING THROUGH PARTS OF
NORTHERN ILLINOIS TODAY, THOUGH THERE IS QUITE THE RANGE OF
SOLUTIONS, INCLUDING A SOME THAT HAVE NO STORMS AT ALL. THIS IS
LIKELY DUE TO THE STRONG ENVIRONMENT THAT WILL BE IN PLACE: 30-40
KTS OF SHEAR, HIGH INSTABILITY FROM A HOT AND HUMID AIRMASS, AND
AMPLE MOISTURE WITH PWATS NEAR 2 INCHES. GIVEN THIS POTENT
ENVIRONMENT, SPC HAS AN ENHANCED (LEVEL 3 OF 5) IN PLACE FOR
NORTHWEST ILLINOIS AND A SLIGHT (LEVEL 2 OF 5) TO THE INTERSTATE
380/HIGHWAY 218 CORRIDOR. HOWEVER, FORECAST CONFIDENCE IS QUITE
LOW, WITH THE MOST LIKELY SCENARIO BEING LOW STORM COVERAGE.
THIS IS DUE TO A NUMBER OF FACTORS, WITH PERHAPS THE GREATEST OF
THESE BEING WARM TEMPERATURES ALOFT. WHILE CAPPING WILL BE WEAK
WITH 850MB TEMPERATURES AROUND 20-25 DEGC, IT COULD SUPPRESS
ANY CONVECTION, SUCH AS WAS SEEN YESTERDAY. IF STORMS DO
DEVELOP, THERE ARE STILL A FEW SCENARIOS THAT COULD PLAY OUT.
SCENARIO 1: STORMS DEVELOP ACROSS WISCONSIN AND MOVE SOUTH-
SOUTHEASTWARD AS AN MCS. THIS MCS MATURES PRIOR TO REACHING
ILLINOIS EARLY TO MID AFTERNOON, ALLOWING FOR IT TO PRODUCE
SWATHS OF DAMAGING WINDS AND TORRENTIAL RAINFALL AS IT MOVES
THROUGH NORTHERN ILLINOIS. IN THIS SCENARIO, THE MCS TRACKS TO
THE EAST OF OUR CWA. WHILE THE FRINGES OF THE MCS COULD STILL
IMPACT PARTS OF OUR CWA ACROSS NORTHWEST ILLINOIS, DAMAGING
WINDS WOULD HAVE A LOWER PROBABILITY BUT STILL BE AN AREA OF
CONCERN.
SCENARIO 2: SIMILAR TO SCENARIO 1, STORMS DEVELOP ACROSS
WISCONSIN, WITH THE MAIN DIFFERENCE BEING A MORE WESTWARD TRACK.
THIS WOULD RESULT IN THE MCS TRACKING OVER OUR CWA'S NORTHWEST
ILLINOIS COUNTIES, AND SLIGHT SHIFTS COULD RESULT IN PARTS OF
EASTERN IOWA ALONG THE MISSISSIPPI RIVER SEEING A FEW STORMS. IN
THIS SCENARIO, THE POTENTIAL FOR DAMAGING WINDS, INCLUDING
SIGNIFICANT WINDS, IS HIGHER. THE PRIMARY IMPACTS WOULD BE
FOCUSED IN NORTHWEST AND NORTH-CENTRAL ILLINOIS.
BY EVENING, THE COLD FRONT WILL BEGIN MAKING ITS WAY THROUGH THE
CWA, SLOWLY PUSHING SOUTHWARD. WHILE THIS MAY NOT OFFER IMMEDIATE
RELIEF IN TEMPERATURES, IT WILL HELP REDUCE HEAT INDICES AND THE
CHANCES FOR HEAT HEADLINES IN THE COMING DAYS.
LONG TERM /TUESDAY THROUGH SUNDAY/
ISSUED AT 301 AM CDT MON JUL 27 2026
ONCE THE FRONT PASSES THROUGH, TUESDAY WILL FEEL MUCH COOLER AS
MORE SEASONABLE TEMPERATURES RETURN. ONE NOTE FOR BEHIND THE
FRONT IS THE POTENTIAL FOR SMOKE IN THE AIR, POSSIBLY EVEN
REDUCED AIR QUALITY AT THE SURFACE. GOES GEOCOLOR SATELLITE
SUNDAY AFTERNOON INDICATED WIDESPREAD SMOKE OVER THE NORTHERN
CONUS ROCKIES INTO THE WESTERN DAKOTAS. RAP AND HRRR EXTENDED
SMOKE FORECASTS INDICATE THIS BEING STEERED SOUTHWARD BEHIND THE
FRONT OVER OUR AREA. THIS IS STILL TOO FAR OUT TO TELL IF IT
WOULD MIX TO NEAR- SURFACE, BUT AT LEAST SOME SMOKY SKY TONIGHT
INTO EARLY TUESDAY LOOKS PROBABLE.
AFTER QUIET AND NEAR TO SLIGHTLY WARMER THAN SEASONABLE
TEMPERATURES WEDNESDAY AND INTO THE DAY THURSDAY, A SLOW MOVING
AND FAIRLY WELL-DEFINED SHORT WAVE IS INDICATED BY GUIDANCE TO
PASS OVER THE AREA LATE THURSDAY NIGHT INTO FRIDAY. THIS LOOKS
LIKE THE NEXT CHANCE OF RAIN.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1215 PM CDT MON JUL 27 2026
THE MORNING INVERSION HAS ERODED BUT HAS BEEN REPLACED BY
MULTIPLE CAPPING INVERSIONS ALOFT. THUS CONVECTION WILL BE
SUPPRESSED UNTIL THE CAPS CAN BE OVER COME; MOST LIKELY DURING
PEAK HEATING. THUS ISOLATED TO SCATTERED (15-35%) COVERAGE IS
POSSIBLE ALONG AND AHEAD OF THE COLD FRONT FROM 20Z/27 THROUGH
02Z/28 ACROSS EASTERN IOWA AND NORTHERN ILLINOIS. AFTER 02Z/28
CONVECTION WILL DISSIPATE BUT HAZE FROM WILDFIRE SMOKE WILL BE
POSSIBLE.
DVN WATCHES/WARNINGS/ADVISORIES
IA...EXTREME HEAT WARNING UNTIL 10 PM CDT THIS EVENING FOR
IAZ040>042-051>054-063>068-076>078-087>089-098-099.
IL...EXTREME HEAT WARNING UNTIL 10 PM CDT THIS EVENING FOR ILZ001-
002-007-009-015>018-024>026-034-035.
MO...EXTREME HEAT WARNING UNTIL 10 PM CDT THIS EVENING FOR MOZ009-
010.
SHORT TERM...ELLINGWORTH
LONG TERM...ELLINGWORTH/FRIEDLEIN
AVIATION...08
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page