707
FXUS63 KLOT 040825
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
325 AM CDT WED JUN 4 2025
KEY MESSAGES
- AXIS OF RAIN WILL SHIFT EVER SO SLOWLY SOUTHEAST OVER THE NEXT
24 HOURS, ENDING FROM THE NORTHWEST TODAY INTO TONIGHT.
- MUCH COOLER TEMPERATURES TODAY, REMAINING QUITE CHILLY NEAR
THE LAKE THURSDAY.
DISCUSSION
ISSUED AT 325 AM CDT WED JUN 4 2025
THROUGH THURSDAY:
AT THE SURFACE, A SLOW MOVING NORTHEAST-SOUTHWEST ORIENTED COLD
FRONT WAS BISECTING OUR CWA EARLY THIS MORNING. A LARGE SWATH OF
RAIN IS LOCATED NEAR AND MOSTLY BEHIND THIS SLOW MOVING FRONT.
ALOFT, A WELL DEFINED SHORTWAVE TROUGH WAS EVIDENT ON WATER
VAPOR IMAGERY MOVING INTO MISSOURI OZARK REGION. ENHANCED LARGE
SCALE ASCENT IN ADVANCE OF THIS FEATURE SHOULD HELP MAINTAIN THE
AXIS OF RAIN IN OUR CWA THIS MORNING AS IT SLOWLY SHIFTS
EASTWARD. BY MIDDAY, THE AXIS OF THIS SHORTWAVE WILL BEGIN TO
MOVE EAST OF OUR CWA, SO ANTICIPATE A GENERAL DECREASE IN
COVERAGE OF RAINFALL THIS AFTERNOON. DESPITE THE SUBSIDENCE IN
THE WAKE OF THIS SHORTWAVE, MOST GUIDANCE DOES DEPICT A RE-
DEVELOPMENT OF CONVECTION, INCLUDING PERHAPS A FEW
THUNDERSTORMS, NEAR AND JUST AHEAD OF THE COLD FRONT THIS
AFTERNOON INTO THIS EVENING. THIS RENEWED DEVELOPMENT IS
EXPECTED MOSTLY SOUTHEAST OF A VALPARAISO TO PONTIAC LINE ACROSS
OUR SOUTHEASTERN CWA.
IN THE WAKE OF THIS FRONT, WINDS WILL TURN NORTH THEN
NORTHEASTERLY WITH MUCH COOLER AIR ADVECTING INTO THE AREA.
OVERCAST SKIES AND WINDS OFF THE LAKE WILL KEEP TEMPERATURES
PARTICULARLY COOL IN THE CHICAGO AREA, WHERE AFTERNOON TEMPS
NEAR THE LAKE SHOULD BE IN THE 50S TODAY. FARTHER NORTHWEST
TOWARD ROCKFORD, SOME THINNING OF THE OVERCAST COULD ALLOW
AFTERNOON TEMPS TO REBOUND A BIT TOWARD 70 DEGREES.
HAVE OPTED TO MAINTAIN SOME NEAR SURFACE SMOKE IN THE GRIDS
WELL BEHIND THE FRONT THIS AFTERNOON INTO TONIGHT. LATEST HRRR
AND RAP GUIDANCE ACTUALLY SUGGEST THE NORTHEAST COMPONENT TO THE
FLOW WILL KEEP THE SURFACE SMOKE WEST OF OUR CWA. WHILE THAT IS
CERTAINLY PLAUSIBLE, CONFIDENCE IS PRETTY LOW AND THERE ARE SOME
REDUCED VSBYS UPSTREAM OVER CENTRAL AND NORTHERN WI, SO TO AVOID
FLIP FLOPPING HAVE MAINTAINED THE SMOKE MENTION IN THE GRIDS AND
FORECAST.
FRONT IS EXPECTED TO SETTLE SOLIDLY SOUTH OF THE AREA AND SHOULD
ALLOW FOR A DECENT DAY WEATHER-WISE THURSDAY. CLOUDINESS IS
EXPECTED TO AT LEAST PARTIALLY CLEAR, ESPECIALLY NORTHERN CWA,
THOUGH THERE IS THE SMOKE WILDCARD, WHICH COULD END UP FILTERING
SUNSHINE AGAIN THURSDAY. AWAY FROM LAKE MICHIGAN, TEMPERATURES
SHOULD REBOUND INTO THE 70S, THOUGH RIGHT ALONG THE IMMEDIATE
SHORELINE IT WILL BE A BATTLE FOR TEMPS TO EVEN REACH THE 60
DEGREE MARK.
- IZZI
THURSDAY NIGHT THROUGH TUESDAY:
CONSENSUS FORECAST GUIDANCE CONTINUES TO FAVOR MOSTLY DRY
CONDITIONS FOR AT LEAST THE NORTH HALF OF THE FORECAST AREA ON
FRIDAY. ENERGY FROM A SOUTHWEST U.S. UPPER-LEVEL LOW WILL
TRAVERSE A STALLED FRONT ACROSS SOUTHERN IL/IN THURSDAY NIGHT
THROUGH FRIDAY, ULTIMATELY FOCUSING MUCH OF THE PRECIP SOUTH OF
THE CWA. HOWEVER, WITH SOME GEFS MEMBERS AND DETERMINISTIC
GUIDANCE BRINGING A MID-LEVEL DEFORMATION AXIS SOLIDLY ACROSS
CENTRAL ILLINOIS, WILL MAINTAIN CHANCE POPS FOR RAIN PRIMARILY
WELL SOUTH OF I-80 FRIDAY AFTERNOON AND EVENING.
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 SUNDAY AFTERNOON AND EVENING. WILL NEED TO
MONITOR FOR A LOW-END SEVERE STORM RISK WITH GUSTY WINDS AS
DECENT EFFECTIVE SHEAR COUNTERACTS MARGINAL MID-LEVEL LAPSE
RATES.
THE UPPER-LEVEL LOW WILL SETTLE OVER THE FAR NORTHERN GREAT
LAKES REGION EARLY NEXT WEEK. A SERIES OF EMBEDDED COMPACT WAVES
ROTATING AROUND THE LOW COULD BRING DIURNALLY-ENHANCED SHOWERS
MONDAY AFTERNOON AND POSSIBLY TUESDAY AFTERNOON CONDITIONAL ON
COINCIDENT TIMING OF THE WAVES WITH PEAK HEATING.
KLUBER
AVIATION /06Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 1255 AM CDT WED JUN 4 2025
SW WINDS AROUND 10 KNOTS WITH A FEW GUSTS NEARING 20 KNOTS AT
TAF ISSUANCE WILL SHIFT NE/NNE UP TO 10 KNOTS WITH THE PASSAGE
OF A COLD FRONT ROUGHLY AROUND 12Z FOR ORD/MDW. WINDS WILL THEN
REMAIN NNE AT 10 KNOTS OR LESS THROUGH THE REMAINDER OF THE
PERIOD.
RA/SHRA ALONG AND BEHIND THE COLD FRONT WILL ALSO BRING QUICKLY
LOWERING CEILINGS. IFR CEILINGS HAVE ALREADY SPREAD TO RFD,
WITH ADDITIONAL UPSTREAM IFR CEILINGS ACROSS SOUTHERN WISCONSIN
EXPECTED TO SPREAD OVER THE CHICAGO TERMINALS AROUND OR SHORTLY
AFTER SUNRISE. ISOLATED -SHRA CURRENTLY AROUND NORTHEAST
ILLINOIS WILL INCREASE IN COVERAGE AND INTENSITY DURING THE PRE-
DAWN HOURS AND MAY RESULT IN PERIODS OF IFR/MVFR VISIBILITY WITH
THE STRONGEST SHOWERS. TS REMAINS POSSIBLE WITH THESE SHRA IN
THE 09-12Z WINDOW, BUT CHANCES OF UNDER 20 PERCENT PRECLUDE
MENTION IN THE TAF AT THIS TIME.
CEILINGS ARE EXPECTED TO GRADUALLY IMPROVE INTO MVFR LEVELS
LATE THIS MORNING AND ESPECIALLY THIS AFTERNOON. FOG MAY DEVELOP
OVER LAKE MICHIGAN AND SLOWLY ADVECT INLAND TODAY AND TONIGHT.
WHILE DIURNAL HEATING SHOULD SCATTER THE LOWEST LAYER OF
CEILINGS ASSOCIATED WITH ANY FOG DURING THE AFTERNOON, IFR
CEILINGS COULD RETURN THIS EVENING AND PERSIST INTO THE
OVERNIGHT HOURS.
LASTLY, WILDFIRE SMOKE HAS RESULTED IN MVFR VISIBILITY WELL
UPSTREAM INTO WESTERN WISCONSIN AND NORTHEAST IOWA. IF THE
HIGHER CONCENTRATIONS UPSTREAM CONTINUE TO PERSIST WITH TIME
TODAY, LOWER VISIBILITY FROM HZ/FU MAY NEED TO BE INCLUDED
BEGINNING LATE THIS AFTERNOON AT THE CHICAGO TERMINALS. HAVE
ALREADY INCLUDED 6SM FOR RFD, BUT THIS VALUE WOULD NEED TO BE
LOWERED AS WELL.
KLUBER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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