742
FXUS63 KDVN 180514
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1214 AM CDT SAT JUL 18 2026
KEY MESSAGES
- HOT AND HUMID CONDITIONS ARE FORECAST TO CONTINUE THROUGH
SATURDAY WITH PEAK AFTERNOON HEAT INDICES OF MID-90S TO LOW
100S. A HEAT ADVISORY HAS BEEN ISSUED FOR COUNTIES ALONG AND
SOUTH OF HIGHWAY 34 BETWEEN NOON AND 7PM SATURDAY WHERE HEAT
INDICES WILL LIKELY (60-80%) EXCEED 100 DEGREES.
- ISOLATED TO SCATTERED SHOWERS AND STORMS (20-50% COVERAGE) ARE
POSSIBLE SATURDAY AFTERNOON. ISOLATED SEVERE STORMS ARE
POSSIBLE (5% CHANCE) SATURDAY, MAINLY IN WEST- CENTRAL
ILLINOIS.
- THERE WILL BE CANADIAN WILDFIRE SMOKE AT TIMES SATURDAY NIGHT
INTO SUNDAY IN THE FORM OF MAINLY HAZY SKIES. HOWEVER, THICKER
CONCENTRATIONS NEAR-SURFACE AND UNHEALTHY AIR QUALITY IS
POSSIBLE ACROSS PARTS OF NORTHWEST ILLINOIS THROUGH TONIGHT.
- A COLD FRONT ON MONDAY POSES A SEVERE WEATHER THREAT, WITH
THE SPC ISSUING A SLIGHT RISK (LEVEL 2 OUT OF 5) FOR POTENTIAL
DAMAGING WINDS.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 143 PM CDT FRI JUL 17 2026
AS THE UPPER-LEVEL RIDGING OVER THE AREA CONTINUES TO BREAK DOWN, A
WEAK SHORTWAVE WILL BE PULLED NORTHWARD, BOOSTING CLOUD COVER AND
POPS THIS AFTERNOON INTO THE OVERNIGHT HOURS AHEAD OF A COLD
FRONT PUSHING SOUTHWARD INTO MINNESOTA AND WISCONSIN. UNLIKE
PREVIOUS DAYS, THE WINDS ARE FORECAST TO BE GENERALLY 5-10 MPH
ACROSS THE AREA, BUT THE SOUTHERLY COMPONENT WILL SUPPORT WEAK
WARM AIR ADVECTION IN THE LOW LEVELS. THIS KEEPS THE HEAT AROUND
THIS AFTERNOON WITH HIGHS IN THE LOW-TO-MID-90S BESIDES THE
AREAS THAT SEE AFTERNOON THUNDERSTORMS, AND OVERNIGHT LOWS ARE
EXPECTED TO BE IN THE MID-70S AHEAD OF THE FRONT.
AN AIR QUALITY ALERT REMAINS IN EFFECT UNTIL MIDNIGHT TONIGHT FOR JO
DAVIESS AND STEPHENSON COUNTIES. AS WINDS SHIFT OUT OF THE SOUTH
THIS AFTERNOON, ANY SMOKE OR HAZE CURRENTLY PRESENT OVER NORTHWEST
ILLINOIS WILL BE ADVECTED NORTHWARD, BUT SMOKE COULD RETURN LATER
INTO THE WEEKEND.
HEADING INTO SATURDAY, THE COLD FRONT IS EXPECTED TO CLEAR THE AREA
FROM NORTH TO SOUTH BEFORE STALLING NEAR THE MISSOURI-IOWA BORDER
OVERNIGHT SATURDAY. SCATTERED THUNDERSTORM DEVELOPMENT WILL BE
FAVORED ALONG THIS FRONT, BUT THE WEAK CONVERGENCE AND
DISPLACEMENT OF THE LOW PRESSURE SYSTEM OVER SOUTHERN QUEBEC
SHOULD KEEP COVERAGE ISOLATED TO SCATTERED AT 20-50%. IN TERMS
OF SEVERE WEATHER, THE SPC DOES HAVE A MARGINAL RISK (LEVEL 1
OF 5) FOR WEST-CENTRAL ILLINOIS, FAR SOUTHEAST IOWA, AND
NORTHEASTERN MISSOURI WHERE THE FRONT IS FORECAST TO BE NEAR
DURING PEAK DAYTIME HEATING. SBCAPE VALUES IN THE RANGE OF
1500-2000 J/KG APPEAR LIKELY (60-90%), BUT THE WEAK 0-6-KM BULK
SHEAR AROUND 20 KNOTS SHOULD PREVENT SIGNIFICANT ORGANIZATION OF
STORMS WITH THE GREATEST HAZARD BEING GUSTY WINDS WITH ANY
STRONG DOWNBURSTS. THE HEAT POTENTIAL REMAINS MAINLY ALONG AND
SOUTH OF INTERSTATE 80 AS DRIER AIR BEHIND THE COLD FRONT IS
FORECAST TO DAMPEN HEAT INDICES IN OUR NORTHERN COUNTIES. A
HEAT ADVISORY HAS BEEN ISSUED FOR COUNTIES ALONG AND SOUTH OF
HIGHWAY 34 WHERE HEAT INDICES WILL LIKELY (60-80%) EXCEED 100
DEGREES FOR SEVERAL HOURS PRIOR TO THE COLD FRONT'S ARRIVAL. IF
CONFIDENCE INCREASES ON THE NORTHERN SIDE OF THE HEAT ADVISORY,
IT COULD BE EXPANDED NORTHWARD. BY SATURDAY NIGHT, POPS
DECREASE WITH THE LOSS OF DIURNAL HEATING AND DRY AIR ADVECTION
FROM THE NORTHERLY WINDS AS LOWS DROP INTO THE UPPER 60S TO LOW
70S. HOWEVER, THE NORTHERLY WINDS COULD ADVECT ADDITIONAL SMOKE
FROM THE CANADIAN AND MINNESOTA WILDFIRES INTO NORTHWEST
ILLINOIS AND NORTHEAST IOWA AND WILL NEED TO BE MONITORED.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
ISSUED AT 143 PM CDT FRI JUL 17 2026
SUNDAY...WITH A HIGH PRESSURE OVER THE GREAT LAKES AND A LONGWAVE
TROUGH OVER THE EASTERN CONUS, SUBSIDENCE RETURNS TO THE AREA AS THE
SKIES CLEAR ONCE AGAIN. SMOKE/HAZE ADVECTION IS EXPECTED TO CONTINUE
INTO NORTHWESTERN ILLINOIS AND EAST-CENTRAL IOWA. WHILE SMOKE
CONCENTRATION AMOUNTS REMAIN UNCERTAINTY, THERE IS THE
POTENTIAL FOR AIR QUALITY TO BE IMPACTED. OUTSIDE THE SMOKE,
TEMPERATURES AND DEW POINTS ARE FORECAST TO BE LOWER THANKS TO
SATURDAY'S COLD FRONT, WITH HIGHS IN THE 80S AND DEW POINTS
BACK INTO THE MID-60S. THESE COMFORTABLE TEMPERATURES DO NOT
LAST LONG THOUGH AS THE NEXT SHORTWAVE DIVES INTO SOUTH-CENTRAL
CANADA SUNDAY NIGHT, DEEPENING A NEW LOW PRESSURE SYSTEM OVER
MANITOBA AND SHIFTING OUR WINDS BACK OUT OF THE SOUTH.
MONDAY-TUESDAY...THE SHORTWAVE TROUGH CONTINUES TO PROPAGATE
SOUTHEASTWARD INTO MINNESOTA AND WISCONSIN AS THE LOW PRESSURE
SHIFTS INTO ONTARIO, SUPPORTED BY THE LEFT-EXIT REGION OF A 100
KT JET STREAK. AN ACCOMPANYING COLD FRONT IS FORECAST TO BE
PUSHED INTO THE MINNESOTA AND NORTHERN IOWA WHERE CONVECTION
WILL BE FAVORED IN THE WARM AIR ADVECTION REGIME, ESPECIALLY
ALONG AND NORTH OF INTERSTATE 80 WHERE THERE IS THE POTENTIAL
FOR STORMS TO TURN STRONG TO SEVERE. LOOKING AT THE LATEST LREF
GUIDANCE, THE JOINT PROBABILITY OF AT LEAST 1000 J/KG OF SBCAPE
AND 35+ KNOTS OF SFC-TO-500 MB BULK SHEAR IS 40-60%. THERE ARE
SIGNALS OF A POTENTIAL MCS DEVELOPMENT ALONG THE RETREATING
BOUNDARY FROM SATURDAY'S COLD FRONT WHICH IS WHY THE SPC HAS
GONE AHEAD AND ISSUED A SLIGHT RISK (LEVEL 2 OF 5) FOR MUCH OF
THE CWA ALONG AND NORTH OF HIGHWAY 34. THE AREA IS SUBJECT TO
CHANGE WITH NEWER MODEL RUNS, BUT THE PRIMARY HAZARD WITH ANY
ORGANIZED CONVECTION WILL BE DAMAGING WINDS.
BY TUESDAY MORNING, THE COLD FRONT SHOULD CLEAR THE AREA FROM
NORTHWEST TO SOUTHEAST WITH THUNDERSTORMS MAINLY IN ILLINOIS DURING
THE MORNING HOURS, AND BY THE AFTERNOON, COLD AND DRY AIR ADVECTION
TAKE OVER AS WINDS SHIFT TO NORTHWESTERLY AND SKIES BEGIN TO CLEAR.
HIGHS WILL LIKELY (80-100%) NOT EVEN REACH 90 ALONG AND NORTH OF
INTERSTATE 80 AS LOWS TUESDAY NIGHT SINK INTO THE UPPER 50S TO MID-
60S (50-70% CHANCE).
WEDNESDAY-FRIDAY...AFTER TUESDAY'S COLD FRONT, THE AREA GETS A
LITTLE BIT OF DEJA VU WITH A HIGH PRESSURE CAMPING OVER THE
CWA, BUT UNLIKE THIS PAST WEEK, THERE WILL BE NO HEAT DOME
OVERHEAD. THIS MEANS THAT THE COOLER, DRIER AIR MASS WILL MODIFY
SLOWLY THROUGH THE END OF NEXT WEEK WITH TEMPERATURES AND DEW
POINTS ONLY CREEPING UP A COUPLE DEGREES EACH DAY. EVEN WITH
MOSTLY SUNNY SKIES, HIGH TEMPERATURES AND DEW POINTS WILL LIKELY
(70-100%) NOT EXCEED 90 DEGREES OR 70 DEGREES, RESPECTIVELY,
DURING THIS TIME PERIOD.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1209 AM CDT SAT JUL 18 2026
SOUTHWEST WINDS WILL PERSIST THROUGH SUNRISE AHEAD OF AN
APPROACHING COLD FRONT. DENSITY ALTITUDES OVER 2500 ARE EXPECTED
SATURDAY AFTERNOON/EVENING. THE COLD FRONT IS FORECAST TO MOVE
THROUGH EASTERN IOWA AND NORTHERN ILLINOIS AFTER 16Z/18. DIURNAL
HEATING WILL RESULT IN ISOLATED (10-25%) COVERAGE OF SHRA/TSRA
SATURDAY AFTERNOON/EVENING. THE PROBABILITY OF A SHRA/TSRA AT
KMLI IS 10 PERCENT AND THUS NO PROB30 WAS INCLUDED. KBRL HAS A
HIGHER RISK OF TSRA DUE TO THE LATER FRONTAL PASSAGE.
DVN WATCHES/WARNINGS/ADVISORIES
IA...HEAT ADVISORY FROM NOON TODAY TO 7 PM CDT THIS EVENING FOR
IAZ087>089-098-099.
IL...HEAT ADVISORY FROM NOON TODAY TO 7 PM CDT THIS EVENING FOR
ILZ025-026-034-035.
MO...HEAT ADVISORY FROM NOON TODAY TO 7 PM CDT THIS EVENING FOR
MOZ009-010.
SHORT TERM...DELAUNE
LONG TERM...DELAUNE
AVIATION...08
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