417
FXUS63 KLOT 032047
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
347 PM CDT TUE JUN 3 2025
KEY MESSAGES
- STRONG TO SEVERE WIND GUSTS FROM AN ORGANIZED THUNDERSTORM
COMPLEX WILL BE POSSIBLE THIS EVENING, MAINLY NEAR AND WEST
OF THE I-39 CORRIDOR.
- A BAND OF SHOWERS AND SOME THUNDERSTORMS WILL MOVE EASTWARD
ACROSS THE AREA TONIGHT THROUGH WEDNESDAY.
- TRENDING DRIER WITH SEASONABLE TO SEASONABLY COOL CONDITIONS
LATE THIS WEEK AND INTO THE WEEKEND.
MESOSCALE
ISSUED AT 347 PM CDT TUE JUN 3 2025
THE ARC OF CONVECTION THAT DEVELOPED EARLY THIS AFTERNOON ALONG
THE NOSE OF A LOW-LEVEL JET AND TRACKED OVER THE NORTHWESTERN
HALF OF OUR CWA HAS SINCE MOVED OVER LAKE MICHIGAN, RESULTING IN
MOSTLY DRY CONDITIONS ACROSS THE FORECAST AREA AT PRESS TIME.
UPSTREAM, A HEALTHY-LOOKING, BOWING MCS DEVELOPED NEAR THE
KANSAS CITY METRO AND IS NOW TRACKING THROUGH NORTHERN AND
CENTRAL MISSOURI. THE AIR MASS IMMEDIATELY UPSTREAM OF THE MCS
ACROSS NORTHEASTERN MISSOURI HAS ALREADY RECOVERED IN THE WAKE
OF THE MORNING CONVECTION THERE WITH RAP OBJECTIVE MESOANALYSIS
INDICATING AROUND 1000-1500 J/KG OF MLCAPE THERE AS OF 20Z.
WITH PLENTY OF CLEARING EVIDENT ON GOES VISIBLE SATELLITE
IMAGERY AHEAD OF THE MCS AND PERSISTENT WARM AIR ADVECTION
ONGOING OFF OF BREEZY SOUTHERLY WINDS, FURTHER DESTABILIZATION
IS EXPECTED ACROSS NORTHEASTERN MISSOURI AND POINTS NORTHEAST
OVER THE NEXT FEW HOURS, WHICH SHOULD ERODE ANY LINGERING MLCIN
IN SOUTHEASTERN IOWA AND NORTHWESTERN ILLINOIS. THUS,
CONFIDENCE IS HIGH THAT THE MCS WILL CONTINUE TO INTENSIFY AS IT
RIDES A DIFFERENTIAL HEATING-REINFORCED INSTABILITY GRADIENT
NORTHEASTWARD TOWARDS THE QUAD CITIES.
THE MCS WILL LIKELY ONLY BEGIN TO WEAKEN THIS EVENING AS IT
RUNS INTO WEAKER INSTABILITY AND INCREASING CONVECTIVE
INHIBITION IN NORTHERN ILLINOIS. IN GENERAL, CAMS DEPICT THIS
HAPPENING IN THE 01Z TO 03Z TIME WINDOW, WHICH IS ROUGHLY WHEN
THE MCS WILL BE TRACKING THROUGH OUR NORTHWESTERN CWA. THUS,
CONTINGENT UPON SUFFICIENT ATMOSPHERIC RECOVERY OCCURRING IN
NORTHERN ILLINOIS IN THE WAKE OF THE EARLIER CONVECTION, IT
APPEARS THAT THERE WILL BE A BRIEF WINDOW THIS EVENING WHERE
STRONG TO SEVERE WIND GUSTS COULD BE OBSERVED IN OUR FORECAST
AREA, MAINLY NEAR AND WEST OF THE I-39 CORRIDOR, BEFORE THE MCS
PETERS OUT. FOR AS LONG AS THE MCS IS ABLE TO MAINTAIN AN
APPRECIABLE INTENSITY, THEN A QLCS SPIN-UP COULD ALSO NOT BE
RULED OUT NEAR/WEST OF I-39 DUE TO THE PRESENCE OF AROUND 40 KTS
OF 0-3 KM SHEAR, THOUGH THE DWINDLING BOUNDARY LAYER-BASED
INSTABILITY WILL OTHERWISE KEEP THE POTENTIAL FOR THIS LIMITED.
OGOREK
DISCUSSION
ISSUED AT 347 PM CDT TUE JUN 3 2025
THROUGH WEDNESDAY:
PLEASE REFERENCE THE MESOSCALE DISCUSSION ABOVE FOR INFORMATION
ABOUT THE STRONG TO SEVERE THUNDERSTORM POTENTIAL THIS EVENING.
AFTER THE MCS DECAYS THIS EVENING, AN ELONGATED BAND OF RAIN
STREAMING NORTHEASTWARD ACROSS AN EASTWARD-INCHING FRONTAL ZONE
WILL PERSIST IN OUR FORECAST AREA THROUGH THE OVERNIGHT HOURS
AND INTO THE DAYTIME TOMORROW. SOME EMBEDDED LIGHTNING COULD
OCCUR LATE THIS EVENING INTO THE OVERNIGHT HOURS, BUT IN
GENERAL, THE OVERALL LIKELIHOOD OF LIGHTNING WILL CONTINUE TO
STEADILY DIMINISH THROUGH THE NIGHT AND INTO TOMORROW MORNING.
AREAS STILL NEAR AND SOUTH OF THE TRUE COLD FRONT BY MID-DAY
TOMORROW (LIKELY LOCATIONS SOUTH OF I-80, BUT ESPECIALLY
LOCATIONS SOUTH OF THE KANKAKEE RIVER) SHOULD THEN SEE A
RENEWED POTENTIAL FOR THUNDERSTORMS DURING THE AFTERNOON AS PRE-
FRONTAL WARM AIR ADVECTION AND FILTERED SUNSHINE CONTRIBUTE TO
DIURNAL DESTABILIZATION. QUESTIONS STILL REMAIN REGARDING
WHETHER THE BETTER INSTABILITY WILL GET AS FAR NORTH AS OUR
SOUTHEASTERN CWA. IF IT DOES, THEN COULDN'T RULE OUT A STRONG
STORM OR TWO OCCURRING IN OUR SOUTHEASTERN COUNTIES, BUT THE
OVERALL BETTER CHANCES FOR THIS SHOULD REMAIN TO OUR SOUTH AND
EAST.
OTHERWISE, FALL-LIKE CONDITIONS CAN BE EXPECTED TOMORROW NORTH
OF THE COLD FRONT WITH ANAFRONTAL RAIN, STRATUS, AND
TEMPERATURES LARGELY IN THE MID 50S TO MID 60S. THE RAIN AND LOW
CLOUDS SHOULD CLEAR OUT FASTER IN OUR FAR NORTHERN CWA
(INCLUDING IN THE ROCKFORD AREA), WHICH COULD ALLOW DAYTIME
TEMPERATURES THERE TO CLIMB INTO THE LOW 70S. HOWEVER, SMOKE
MODELS INDICATE THAT ANOTHER PLUME OF CANADIAN WILDFIRE SMOKE
SHOULD DESCEND INTO THE AREA BEHIND THE ANAFRONTAL RAIN, WHICH
WILL LEAD TO HAZY SKIES ONCE AGAIN WHEREVER THE STRATUS HAS
CLEARED OUT, AND COULD POTENTIALLY RESULT IN SOME SMOKE
CONCENTRATIONS BEING OBSERVED AT GROUND LEVEL ONCE AGAIN AS WELL.
OGOREK
WEDNESDAY NIGHT THROUGH MONDAY:
WEDNESDAY'S COLD FRONT WILL CONTINUE TO SAG SOUTHWARD WEDNESDAY
NIGHT, WITH THE REMAINING SOUTHEAST PORTIONS OF THE CWA CLEARED
OF THE FRONT BY MID-EVENING AND REMAINING SHOWERS AFTER
MIDNIGHT. THE FRONT WILL SETTLE JUST NORTH OF THE OHIO RIVER
VALLEY BY THURSDAY MORNING AS SURFACE HIGH PRESSURE DRIFTS
ACROSS THE UPPER GREAT LAKES. THIS WILL FAVOR A DRY AND MOSTLY
SUNNY DAY ON THURSDAY WITH HIGHS IN THE MID TO UPPER 70S INLAND
AND 60S ALONG THE LAKE.
CONSENSUS GUIDANCE IS FOR A WAVE ACROSS THE CENTRAL ROCKIES TO
PICKUP OR ABSORB AT LEAST SOME ENERGY FROM AN UPPER-LEVEL LOW
OVER THE SOUTHWEST U.S. WEDNESDAY INTO THURSDAY. A WEAK SURFACE
LOW DEVELOPING FROM CONVECTIVE FEEDBACK OVER THE CENTRAL GREAT
PLAINS THURSDAY EVENING WILL TRAVERSE THE FRONT ON FRIDAY.
GUIDANCE HAS COME INTO SOMEWHAT BETTER AGREEMENT THAT THE MAIN
IMPACTS FROM THIS SYSTEM DEVELOPING ALONG THE FRONT WILL REMAIN
SOUTH OF MUCH OF THE FORECAST AREA, THOUGH SOME SHOWERS COULD
BRUSH THE SOUTHERN CWA FRIDAY AFTERNOON AND EVENING. OTHERWISE,
SEASONABLY COOL CONDITIONS UNDER PARTLY TO MOSTLY CLOUDY SKIES
CAN BE EXPECTED ON FRIDAY.
HIGH PRESSURE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON
SATURDAY WILL PRODUCE SEASONABLE CONDITIONS AND DRY WEATHER. AN
UPPER-LEVEL LOW OVER THE FAR NORTHERN GREAT LAKES WILL THEN PUSH
A COLD FRONT WITH THE POTENTIAL FOR SHOWERS AND A FEW STORMS
ACROSS THE AREA LATE SUNDAY INTO MONDAY MORNING.
KLUBER
AVIATION /18Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 1220 PM CDT TUE JUN 3 2025
AN MCV-LIKE FEATURE MOVING THROUGH EASTERN IOWA WILL CONTINUE
TO SUPPORT A BAND OF SHOWERS AND THUNDERSTORMS ACROSS
NORTHWESTERN ILLINOIS THIS AFTERNOON. COVERAGE OF THUNDER SHOULD
BE HIGHEST AT RFD AND DPA, WHERE -TSRA WILL BE ADVERTISED IN
OUTGOING TEMPO GROUPS. MEANWHILE, -SHRA WILL BE ADVERTISED AT
ORD/MDW, THOUGH A LIGHTNING STRIKE OR TWO CANNOT BE RULED OUT
(20-30% CHANCE). AHEAD OF THE BAND OF SHOWERS AND STORMS,
SOUTHWESTERLY WIND GUSTS NEAR 35 KT ARE EXPECTED TO PREVAIL.
BEHIND THE BAND OF SHOWERS AND THUNDERSTORMS, SOUTHWEST WINDS
MAY BRIEFLY EASE TO NEAR OR EVEN BELOW 30KT, THOUGH CONFIDENCE
IS TOO LOW TO INTRODUCE A FM GROUP IN THE OUTGOING TAFS. AS AN
UPPER-LEVEL WAVE CURRENTLY ACROSS THE PLAINS APPROACHES THIS
EVENING, SHOWERS AND STORMS ARE EXPECTED TO REDEVELOP WEST OF
THE MISSISSIPPI RIVER AND DRIFT EAST-NORTHEASTWARD AFTER SUNSET.
SIMILAR TO THIS AFTERNOON, THINK THAT COVERAGE OF THUNDER WILL
BE HIGHEST ACROSS NORTHWESTERN IL AND IN PARTICULARLY NEAR RFD.
SO, WILL ADVERTISE ANOTHER TEMPO FOR -TSRA AT RFD. SHOWERS MAY
STRUGGLE TO MAKE IT TO THE CHICAGO TERMINALS UNTIL WELL AFTER
DARK IF NOT MIDNIGHT, SO WILL MAINTAIN THE INHERITED TIMING OF
PREVAILING -SHRA AT DPA/MDW/ORD/GYY OF 08 TO 09Z TONIGHT.
SOUTHWEST WINDS WILL REMAIN BREEZY WITH GUSTS OF 25 TO LOCALLY
30 KT THROUGH THE EVENING TO OVERNIGHT HOURS ESPECIALLY AHEAD OF
THE SHOWERS.
CEILINGS ARE EXPECTED TO GRADUALLY LOWER OVERNIGHT AS SHOWERS
BECOME WIDESPREAD AND A FRONTAL BOUNDARY STALLS OVER THE REGION.
GUIDANCE REMAINS BULLISH IN WIDESPREAD LIFR TO IFR CIGS
DEVELOPING BY DAYBREAK, BUT WILL TAKE A CAUTIOUS APPROACH AND
ADVERTISE OVC009 BY 13Z TOMORROW AS WINDS SHIFT TO A NORTH TO
NORTHEASTERLY DIRECTION. ON-AND-OFF SHOWERS WITH PERIODS OF IFR
TO LOW-END MVFR CIGS WILL THEN PREVAIL THROUGH THE REMAINDER OF
THE TAF PERIOD.
BORCHARDT
MARINE
ISSUED AT 312 AM CDT TUE JUN 3 2025
POTENTIAL EXISTS FOR A PERIOD OF NEAR GALE TO LOW END GALE
FORCE SOUTH-SOUTHWEST WINDS THIS AFTERNOON AND EVENING. THERE IS
SOME UNCERTAINTY REGARDING JUST HOW STRONG THE WINDS WILL GET
GIVEN THE INCREASING CLOUD COVER, SO OPTED TO JUST MAINTAIN
MENTION OF GALE FORCE GUSTS AND HOLD OFF ON A GALE WARNING. IF
IT BECOMES CLEAR THAT THERE WILL BE A PERIOD OF SOLID GALES,
THEN A SHORT FUSED GALE WARNING COULD BE NEEDED FOR THE
NEARSHORE WATERS FOR THIS AFTERNOON AND EVENING. THE STRONGEST
WINDS AND ANY GALES WOULD LIKELY BE CONFINED TO AREAS CLOSE TO
THE SHORE WITH A STRONGLY STABLE MARINE LAYER LIMITING THE
MAGNITUDE OF WINDS/GUSTS FARTHER FROM THE SHORE.
- IZZI
LOT WATCHES/WARNINGS/ADVISORIES
IL...BEACH HAZARDS STATEMENT UNTIL 7 PM CDT THIS EVENING FOR ILZ006-
ILZ103.
IN...NONE.
LM...GALE WARNING UNTIL 10 PM CDT THIS EVENING FOR THE IL AND IN
NEARSHORE WATERS.
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