945
FXUS63 KLOT 072344
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
644 PM CDT SUN JUN 7 2026
KEY MESSAGES
- SHOWERS AND STORMS ARE EXPECTED THIS AFTERNOON/EVENING WITH
THE HIGHEST COVERAGE SOUTHWEST OF THE CHICAGO METRO, SOME
CAPABLE OF TORRENTIAL DOWNPOURS AND GUSTY WINDS.
- AN ADDITIONAL ROUND OF SHOWERS AND STORMS ARE EXPECTED AREAWIDE
TOMORROW.
- HEAT AND HUMIDITY INCREASE MID-WEEK WITH HEAT INDICES IN THE
MID TO UPPER 90S.
- LOW CHANCES FOR SHOWERS AND STORMS TUESDAY AND WEDNESDAY, BUT
THERE IS A CHANCE THAT THURSDAY COULD BE THE NEXT THREAT FOR
SEVERE WEATHER.
DISCUSSION
ISSUED AT 233 PM CDT SUN JUN 7 2026
SPC MESOANALYSIS DEPICTS A STOUT THETA-E GRADIENT ALONG A
SURFACE STATIONARY FRONT FROM NORTHWEST ILLINOIS THROUGH GARY,
INDIANA. LUCKILY FOR THE CHICAGO METRO, MOST OF THE ACTIVITY
THIS AFTERNOON AND EVENING SHOULD BE ALONG AND SOUTHWEST OF THIS
BOUNDARY. STORM MOTIONS ARE INCREDIBLY SLOW (TO THE NORTH-
NORTHEAST AT 10 TO 15 MPH). WHILE WET MICROBURSTS PRODUCING
LOCALLY GUSTY WINDS ARE POSSIBLE, THE MAIN HAZARD THIS AFTERNOON
IS BECOMING A HYDRO CONCERN. INSTANTANEOUS RAIN RATES ON MRMS
FOR STORMS CLOSER TO THE MISSISSIPPI RIVER (WHERE THE BETTER
FORCING IS LOCATED) HAVE HAD ISOLATED STORMS PRODUCING OVER 2
INCH PER HOUR RATES! FOR NOW, THE HIGHER RAIN TOTALS HAVE
REMAINED WEST OF THE AREA, BUT THE THREAT FOR LOCALIZED
TORRENTIAL DOWNPOURS THIS AFTERNOON AND EVENING KEEPS THE THREAT
FOR FLASH FLOODING PREVALENT.
AN UPPER LEVEL TROUGH OVER THE CENTRAL PLAINS IS EXPECTED TO
SLOWLY MOVE EAST THROUGH THE OVERNIGHT AND OVER NORTHERN
ILLINOIS ON MONDAY. THIS SHOULD EVENTUALLY KICK THE
AFOREMENTIONED STATIONARY FRONT NORTHEASTWARD AND PRODUCE
WIDESPREAD SHOWERS AND STORMS ACROSS THE FORECAST AREA TOMORROW.
WITH THE WAVE BEING MORE PROGRESSIVE IN NATURE, THE THREAT FOR
FLOODING CONCERNS IS SOMEWHAT LOWER THAN THIS AFTERNOON. BUT
GIVEN THE AMOUNT OF MOISTURE AVAILABLE AND HOW EFFICIENT THE
RAIN SHOULD BE PRODUCED, FLOODING CONCERNS REMAIN ELEVATED
TOMORROW. ADDITIONALLY, THERE WILL REMAIN A THREAT FOR WET
MICROBURSTS PRODUCING LOCALIZED GUSTY WINDS. WITH HIGH CAPE,
WEAK SHEAR, AND AMPLE AMBIENT VORTICITY, A FUNNEL CLOUD OR TWO
CANNOT BE COMPLETELY RULED OUT, PARTICULARLY IN THE AFTERNOON
WHEN THE TROUGH AXIS IS OVERHEAD.
WEAK RIDGING WILL GROW ON TUESDAY FROM THE WEST. LINGERING
SHOWERS AND SOME ISOLATED STORMS ARE POSSIBLE IN THE MORNING,
MAINLY EAST OF I-55. WHILE SOME AFTERNOON SUMMERTIME POP-UP
SHOWERS ARE POSSIBLE, WITH WEAK FORCING, THE FORECAST FOR
TUESDAY AND WEDNESDAY IS TRENDING DRIER. MORE IMPACTFULLY, THIS
RIDGE WILL DRIVE FLOW BACK TO SOUTHWESTERLY AND ADVECT IN A
MUCH WARMER, AND MUGGY, AIRMASS. 850 MB TEMPERATURES ARE
EXPECTED TO INCREASE TO AND POTENTIALLY IN EXCESS OF 20C.
SURFACE TEMPERATURES ARE EXPECTED TO CLIMB ABOVE NORMAL INTO THE
MID TO UPPER 80S AND EVEN THE LOW 90S. WITH FORECASTED DEW
POINTS IN THE 70S, HEAT INDICES ARE EXPECTED TO CLIMB INTO THE
MID TO UPPER 90S EACH DAY.
THAT RIDGE AXIS IS EXPECTED TO SLIDE EASTWARD OVER THE AREA ON
WENDESDAY AS THE NEXT LONG WAVE TROUGH SETS UP OVER THE NORTHERN
PLAINS. AN UPPER LEVEL LOW IS EXPECTED TO DEEPEN WEDNESDAY NIGHT
OVER MANITOBA WITH A STRENGTHENING 100 KNOT UPPER LEVEL JET
EMBEDDED IN THE TROUGH. A REFLECTED SURFACE LOW OVER SOUTHERN
CANADA IS EXPECTED TO DEVELOP WITH A COLD FRONT DRAPED SOUTHWARD
DOWN THE PLAINS. THERE IS A LOT OF MODEL UNCERTAINTY ON STORM
DEVELOPMENT ALONG THE FRONT ON WEDNESDAY. THERE IS A NON-ZERO
CHANCE THAT A MCS DEVELOPS AND ARRIVES IN NORTHWEST ILLINOIS
OVERNIGHT, IT WOULD ARRIVE IN A LESS THAN FAVORABLE TIME OF
DAY. MODELS ARE SHOWING A LITTLE BETTER CONSISTENCY WITH SHOWERS
AND STORMS DEVELOPING WITH THE BETTER FORCING WITH THE FRONT ON
THURSDAY. WITH STRONG LOW LEVEL FLOW, A STOUT UPPER LEVEL JET
FOR SYNOPTIC FORCING, AND MUCAPE VALUES 2000-3000 J/KG, AN
EASTWARD PROPAGATING SQUALL LINE MAY DEVELOP WITH STRONG TO
POSSIBLY EVEN SEVERE STORMS THURSDAY. LASTLY, THERE IS ALSO A
LITTLE UNCERTAINTY ON TEMPERATURES FOR THURSDAY DUE TO THE
FRONT. IT COULD SET UP AS ANOTHER HOT AND HUMID DAY AT FIRST,
BUT THE TIMING OF THE FRONT MAY IMPACT MAX TEMPS.
QUASI-ZONAL FLOW ALOFT IS EXPECTED TO DEVELOP BEHIND THE FRONTAL
PASSAGE ON THURSDAY. TEMPERATURES SHOULD BECOME SLIGHTLY MORE
MUTED AT THE END OF THE WEEK. ANOTHER UPPER LEVEL WAVE MAY PASS
OVER ON SATURDAY PROVIDING ANOTHER CHANCE FOR SHOWERS AND STORMS
OVER THE WEEKEND, BUT LOW CONFIDENCE IN TIMING AND STRENGTH AT
THIS DISTANCE.
DK
AVIATION /00Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 644 PM CDT SUN JUN 7 2026
FORECAST CONCERNS INCLUDE...
SHOWERS THIS EVENING.
CHANCE OF THUNDERSTORMS OVERNIGHT/PREDAWN HOURS.
SCATTERED THUNDERSTORMS MONDAY AFTERNOON INTO MONDAY EVENING.
AN AREA OF SHOWERS WILL CONTINUE MOVING NORTH ACROSS THE
TERMINALS THIS EVENING. THUNDER IS NOT EXPECTED AT THE TERMINALS,
BUT ISOLATED THUNDERSTORMS WILL REMAIN POSSIBLE SOUTH AND
SOUTHWEST OF THE TERMINALS THIS EVENING. VISIBILITIES MAY
BRIEFLY LOWER INTO THE 2SM RANGE ALONG WITH BRIEF MVFR CIGS
WITH THIS CURRENT SHOWER ACTIVITY.
THERE IS A CHANCE FOR THUNDERSTORMS IN THE PREDAWN HOURS MONDAY
MORNING ACROSS MOST OF NORTHERN IL AND AT THE TERMINALS. WHILE
CONFIDENCE IS LOW, IF THUNDERSTORMS OCCUR, THEY WILL LIKELY
DEVELOP RIGHT OVER THE TERMINALS AND OPTED TO INCLUDE PROB
MENTION FOR THIS POTENTIAL.
THERE WILL BE ANOTHER CHANCE OF THUNDERSTORMS MONDAY AFTERNOON
INTO MONDAY EVENING. THERE WILL LIKELY NEED TO BE CHANGES TO
THUNDER TIMING WITH LATER FORECASTS WITH PERHAPS THE BEST
THUNDER TIMING AT THE CHICAGO TERMINALS IN THE LATE AFTERNOON
THROUGH EARLY/MID EVENING.
EASTERLY WINDS GENERALLY LESS THAN 10KT WILL BECOME SOUTHEAST
OVERNIGHT AND THEN INCREASE INTO THE 10-15KT RANGE MONDAY
MORNING WITH SOME HIGHER GUSTS INTO THE 20KT RANGE POSSIBLE
MONDAY AFTERNOON. DEPENDING ON THE PRECIPITATION COVERAGE AND
POSSIBLE OUTFLOW BOUNDARIES, WIND DIRECTIONS MAY TURN SOUTHERLY
OR SOUTH/SOUTHWESTERLY MONDAY AFTERNOON. CMS
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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