855
FXUS63 KLOT 011916
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
216 PM CDT SUN JUN 1 2025
KEY MESSAGES
- HAZY SKIES PREVAIL THROUGH MONDAY FROM CANADIAN WILDFIRE
SMOKE. PATCHY SMOKE POSSIBLE NEAR THE SURFACE MONDAY
AFTERNOON.
- ABOVE AVERAGE TEMPERATURES EXPECTED MONDAY AND TUESDAY
- A PERIOD OF SHOWERS AND STORMS EXPECTED LATE TUESDAY THROUGH
EARLY WEDNESDAY.
- MUCH LOWER CONFIDENCE, BUT A SECOND ROUND OF SHOWERS AND
T-STORMS IS POSSIBLE LATE WEDNESDAY INTO THURSDAY.
DISCUSSION
ISSUED AT 216 PM CDT SUN JUN 1 2025
QUIET CONDITIONS REMAIN THROUGH THE OVERNIGHT, THANKS TO THE
HIGH PRESSURE IN THE REGION. EASTERLY WINDS WILL BE LIGHT
TONIGHT BEFORE VEERING TO THE SOUTHWEST ON MONDAY. NO
PRECIPITATION EXPECTED UNTIL TUESDAY NIGHT.
AN UPPER-LEVEL RIDGE OVER THE PLAINS WILL SLOWLY CONTINUE TO
MOVE EAST TOWARD THE GREAT LAKES, KEEPING NORTH TO NORTHWEST
FLOW ALOFT. THIS KEEPS THE MAIN IMPACTS IN THE SHORT TERM
FORECAST CENTERED ON THE SMOKE FROM THE CANADIAN WILDFIRES
MOVING OVER THE AREA (DESPITE SURFACE WINDS OUT OF THE SOUTHWEST
ON MONDAY). MODELS ARE STILL SUGGESTING THAT THE HIGHER
CONCENTRATION OF SMOKE PARTICLES WILL MOVE OVER NORTHERN
ILLINOIS TOMORROW. MODEL SOUNDINGS ARE SUGGESTING DIURNAL MIXING
COULD BE FAIRLY DEEP TOMORROW WITH A VERY WEAK INVERSION AROUND
5000 FEET. WITH BETTER AGREEMENT IN THE NEAR SURFACE SMOKE
MODELS SUGGESTING THAT MIXING COULD BRING AT LEAST SOME OF THE
SMOKE DOWN TO THE SURFACE, IT WAS DECIDED TO ADD PATCHY SMOKE TO
THE FORECAST FOR ALL AREAS EXCEPT FORD, IROQUOIS AND THE
COUNTIES IN NORTHWEST INDIANA. SMOKE GETTING TO THOSE AREAS WILL
BE MONITORED, BUT THE PLUME MIGHT NOT REACH THERE UNTIL LATER
WHEN IT IS A LESS FAVORABLE TIME OF DAY FOR DEEPER BOUNDARY
LAYER MIXING. THIS WILL REMAIN A LOWER CONFIDENCE FORECAST GIVEN
THE UNCERTAINTY ON HOW DEEP THE MIXING WILL BE. NEVERTHELESS,
HAZY SKIES ARE EXPECTED TO PERSIST ACROSS THE ENTIRE AREA DURING
WHAT WOULD NORMALLY BE A PERIOD WITH LITTLE CLOUD COVER.
LASTLY, THE EURO AND THE NBM ARE STILL KEEPING WARM TEMPERATURES
ACROSS THE AREA, OTHER MODELS ARE STARTING TO PICK UP ON THE
FACT THAT WITH HAZY/SMOKY SKIES, MAX TEMPERATURES ORIGINALLY
ANTICIPATED MAY NOT BE REALIZED. WHILE TEMPERATURES ARE STILL
CURRENTLY EXPECTED TO REACH THE 80S, DEPENDING ON THE SMOKE
CONCENTRATION, THEY MAY STRUGGLE TO GET TO THE MID TO UPPER
80S.
THE UPPER-LEVEL FLOW PATTERN FINALLY SHIFTS WESTERLY MONDAY
NIGHT, THEN SOUTHWESTERLY TUESDAY MORNING AS THE NEXT UPPER-
LEVEL LOW MOVES OVER THE HUDSON BAY EXTENDING OVER THE NORTHERN
PLAINS. THERE IS HIGHER CONFIDENCE THAT THIS WILL EFFECTIVELY
(FINALLY) PUSH THE SMOKE EAST OF THE AREA. ALTHOUGH THERE IS
LOWER CONFIDENCE IN THE EXACT TIMING OF IMPROVEMENT IN HAZY SKY
CONDITIONS, AN OVERALL IMPROVING TREND IS ANTICIPATED THROUGH
THE DAY TUESDAY. WITH SMOKE EXITING THE AREA, THERE IS BETTER
CHANCES FOR TEMPERATURES REACHING INTO THE UPPER 80S WITH A
NON-ZERO CHANCE OF A COUPLE OF 90 DEGREE READINGS.
AN UPPER-LEVEL SHORT WAVE TROUGH OVER SOUTHERN COLORADO
(EMBEDDED IN THE LONGER WAVE CONNECTED TO THE UPPER LEVEL LOW)
WILL MOVE TOWARD THE GREAT LAKES TUESDAY NIGHT AND WEDNESDAY
MORNING. A SURFACE COLD FRONT EXTENDING FROM LAKE SUPERIOR TO
KANSAS WILL MOVE EASTWARD OVERNIGHT PROVIDING AMPLE FORCING FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP. LAPSE RATES ARE LOOKING
FAIRLY WEAK, AND THE SYSTEM WILL BE PASSING OVER DURING A LESS
THAN FAVORABLE TIME. GIVEN THE LOWER INSTABILITY, THERE IS LOWER
CONFIDENCE IN THE SEVERE RISK ON TUESDAY THOUGH IT CANNOT BE
COMPLETELY RULED OUT. ESPECIALLY FOR AREA WEST OF THE FOX VALLEY
WHERE IT MIGHT ARRIVE EARLIER IN THE AFTERNOON.
MODELS ARE STILL DISAGREEING ON HOW QUICK THIS SYSTEM EXITS.
THE GFS SOLUTIONS KEEP THIS FAIRLY PROGRESSIVE WHICH WOULD
RESULT IN DRIER CONDITIONS AROUND THE ROCKFORD METRO WHILE
SHOWERS CONTINUE AROUND AND SOUTHEAST OF INTERSTATE 55 ON
WEDNESDAY. THEN THE NEXT UPPER-LEVEL SHORT WAVE FROM OVER THE
DESERT SOUTHWEST WOULD ARRIVE LATE THURSDAY NIGHT INTO FRIDAY
FOR ANOTHER ROUND OF SHOWERS AND STORMS. HOWEVER, THE EURO HAS A
MUCH SLOWER PROGRESSION SUGGESTING IT STALLING AND TURNING INTO
A PSEUDO STATIONARY FRONT OVER THE SOUTHEASTERN PORTIONS OF THE
CWA, BEFORE THE NEXT SHORT WAVE KICKS IT EAST AND BRINGS RAIN
ON FRIDAY. THIS PROVIDES LOWER CONFIDENCE IN THE OVERALL TREND
AND PREVENTED MAKING MUCH ADJUSTMENTS TO THE POPS THAT THE NBM
PROVIDED. CONSIDERING HOW DRY THE FORECAST HAS BEEN AS OF
RECENTLY, THE MAIN FORECAST NOTE IS THE PATTERN IS LOOKING
FAVORABLE FOR INCLEMENT WEATHER FROM MID WEEK AND INTO THE
WEEKEND. IT IS THE TIMING OF RAINY VERSUS DRY PERIODS THAT WILL
NEED TO BE IRONED OUT.
TEMPERATURES RETURN TO MORE SEASONABLE VALUES FOR THE SECOND
HALF OF THE WEEK AND INTO THE WEEKEND. SHOWER CHANCES CANNOT BE
COMPLETELY RULED OUT NEXT WEEKEND, BUT CURRENT GUIDANCES FAVORS
MORE DRIER PERIODS THAN WET.
DK
AVIATION /18Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 1235 PM CDT SUN JUN 1 2025
ONLY REAL ITEM OF NOTE DURING THE PERIOD REVOLVES AROUND THE
WILDFIRE SMOKE THAT CONTINUES TO ENCOMPASSES MUCH OF THE UPPER
MIDWEST AND WESTERN GREAT LAKES EARLY THIS AFTERNOON. LOCALLY,
THE SMOKE THIS AFTERNOON INTO TONIGHT IS EXPECTED TO REMAIN
ALOFT, THOUGH THE LEVEL AT WHICH THE HIGHEST CONCENTRATION
EXISTS IS ANTICIPATED TO GRADUALLY LOWER WITH TIME, AND MAY
BUILD DOWN NEAR THE SURFACE FOR A PERIOD DURING THE DAY MONDAY.
IF THIS OCCURS, THERE COULD BE SOME VSBY RESTRICTIONS THROUGH
MONDAY AFTERNOON. WHILE IT REMAINS UNCERTAIN HOW MUCH OF AN
IMPACT THERE WILL BE TO VSBYS AND CIGS WITH THIS SMOKE ON
MONDAY, A REASONABLE WORST CASE SCENARIO WOULD BE MVFR CIGS AND
VSBY'S. WE WILL CONTINUE TO MONITOR THIS POTENTIAL, BUT FOR THE
TIME BEING WE WILL ONLY HINT AT SOME MINOR VSBY RESTRICTIONS ON
MONDAY.
ASIDE FROM THE SMOKE, AND WHAT IMPACTS TO CIGS AND VSBY'S IT
PRODUCES, CONDITIONS WILL OTHERWISE BE QUIET. EXPECT WINDS TO BE
PRIMARILY FROM THE EAST-NORTHEAST AROUND 10 KT AT THE CHICAGO
AREA TERMINALS THIS AFTERNOON INTO THIS EVENING. WINDS WILL THEN
SHIFT TO THE SOUTH-SOUTHWEST MONDAY MORNING.
KJB
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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