248
FXUS63 KLOT 312316
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
616 PM CDT SAT MAY 31 2025
KEY MESSAGES
- WILDFIRE SMOKE FROM CANADIAN FIRES WILL CONTINUE TO FILTER
OVER THE AREA THROUGH THE WEEKEND. MOST OF THIS SMOKE SHOULD
REMAIN ALOFT AND RESULT IN HAZY SKIES.
- ABOVE AVERAGE TEMPERATURES EXPECTED EARLY NEXT WEEK, WITH
WARMTH RIGHT UP TO THE LAKEFRONT.
- POTENTIALLY WETTER PATTERN SETTING UP MIDWEEK WITH ONE OR
MORE ROUNDS OF SHOWERS/STORMS POSSIBLE TUES NIGHT THROUGH
THURSDAY.
DISCUSSION
ISSUED AT 200 PM CDT SAT MAY 31 2025
THROUGH SUNDAY NIGHT:
A LONG WAVE TROUGH OVER EASTERN CANADA KEEP NORTHERLY FLOW OVER
NORTHEASTERN ILLINOIS AND NORTHWESTERN INDIANA THIS EVENING.
THERE IS A SHORT WAVE EMBEDDED IN THE LONGER WAVE PASSING SOUTH
OVER IOWA AND MISSOURI LATER THIS EVENING, BUT BEING SO FAR
REMOVED FROM THE BETTER FORCING, NO PRECIP IS EXPECTED. THERE IS
A SMALL RIBBON OF MID LAYER MOISTURE DRAPED FROM A ROCKFORD TO
PONTIAC LINE ALLOWING FOR SOME PARTLY CLOUDY SKIES. BUT THOSE
CLOUDS ARE EXPECTED TO DRIFT WEST AWAY FROM THE AREA TONIGHT.
WHILE MOST OBSERVATIONS ARE RECORDING "SKY: CLEAR", ONE LOOK
OUTSIDE (OR VIA TRUE COLOR SATELLITE IMAGERY) AND THERE IS A BIT
OF A HAZE IN THE SKIES AS A RESULT OF CANADIAN WILDFIRE SMOKE
RIDING THE NORTHERLY FLOW OVER THE AREA. NOT ONLY WAS SKY COVER
KEPT UP IN THE FORECAST DUE TO THE HAZY CONDITIONS, THE HAZY
CONDITIONS WERE EXTENDED INTO MONDAY MORNING AS MODELS ARE
SUGGESTING THE THICKEST PLUME ALOFT IS NOT EXPECTED TO DRIFT
OVER THE AREA UNTIL A LITTLE LATER THAN ORIGINALLY ANTICIPATED.
THE CURRENT EXPECTATION IS FOR THE SMOKE TO REMAIN ALOFT, BUT
TRENDS WILL BE MONITORED CLOSELY.
AN UPPER LEVEL RIDGE WILL SLOWLY MOVE EASTWARD TOWARD THE AREA
ON SUNDAY. TEMPERATURES ARE EXPECTED TO BE MID TO UPPER 60S
CLOSER TO THE LAKE AND MID TO UPPER 70S FARTHER INLAND UNDER
"SUNNY" SKIES (AGAIN, NOT COUNTING THE HAZE). ALTHOUGH IT SHOULD
BE NOTED THAT THERE IS SLIGHTLY LOWER CONFIDENCE IN THE
TEMPERATURE FORECAST GIVEN THE UNCERTAINTY IN THE AMOUNT OF
SMOKE ALOFT WHICH MAY LIMIT HEATING.
DK
MONDAY THROUGH SATURDAY:
MID AND UPPER LEVEL RIDGE IS PROGGED TO BUILD EASTWARD ACROSS
THE MISSISSIPPI VALLEY AND GREAT LAKES REGION MONDAY INTO
TUESDAY. SOUTHERLY WINDS AND WARM AIR ADVECTION SHOULD SET THE
STAGE FOR A COUPLE OF DAYS WITH VERY WARM TEMPERATURES. WHILE IT
LOOKS LIKE MONDAY SHOULD BE LARGELY CLOUD-FREE, THERE IS A
GREAT DEAL OF UNCERTAINTY REGARDING HOW MUCH RECYCLED UPPER
LEVEL SMOKE COULD BE AROUND MONDAY. IF THERE IS AN UPPER LEVEL
LAYER OF SMOKE IT WOULD LIKELY TEMPER INSOLATION SOME AND RESULT
IN TEMPS A BIT COOLER THAN CURRENTLY FORECAST. BY TUESDAY, ANY
SMOKE SHOULD BE SAFELY BLOWN WELL TO OUR NORTH AND EAST, BUT
CLOUDINESS WILL PROBABLY BE ON THE INCREASE IN ADVANCE OF THE
NEXT SYSTEM. DESPITE SOME INCREASE IN CLOUD COVER, STRONG
SOUTHERLY WINDS SHOULD STILL ALLOW FOR HIGHS TO CLIMB WELL INTO
THE 80S TO PERHAPS SOME LOW 90S IF CLOUDS ARE A BIT SLOWER TO
ARRIVE.
UPPER TROUGH AND ASSOCIATED SURFACE COLD FRONT ARE PROGGED TO
MOVE ACROSS THE ARE TUESDAY NIGHT INTO EARLY WEDNESDAY WITH
CHANCES FOR SHOWERS AND THUNDERSTORMS. MOISTURE RETURN FROM THE
GULF WILL BE SOMEWHAT STUNTED BY SFC RIDGING BEING SLOW TO MOVE
OFF TO THE EAST AND ALLOW FOR BETTER MOISTURE RETURN. THIS COULD
TEMPER THE SEVERE THREAT SOME, BUT AT THIS DISTANCE CAN'T ARGUE
WITH LIKELY POPS OFFERED UP BY THE NBM GIVEN THE RESPECTABLE
FORCING.
THERE REMAINS SPREAD IN THE MEDIUM RANGE GUIDANCE LATER
WEDNESDAY THROUGH THURSDAY REGARDING HOW FAR SOUTH THIS BOUNDARY
SETTLES. THE 12Z OPERATIONAL RUNS OF THE GFS AND ECMWF BOTH
EJECT OUT AN UPPER LOW FROM THE SOUTHWEST WITH THIS SHEARING OUT
SHORTWAVE RIDING THE WEST-SOUTHWESTERLY FLOW INTO THE MIDWEST,
SIMILAR TO THE 00Z RUNS. THERE IS SIGNIFICANT SPREAD IN BOTH
MODELS' ENSEMBLE SUITES IN HOW THIS UPPER LOW EJECTION IS
HANDLED, SO CONFIDENCE IS STILL PRETTY LOW. IF THIS SHEARING OUT
UPPER LOW WERE TO EJECT OUT IN AND DRAG THAT BOUNDARY BACK
NORTH, THERE WOULD LIKELY BE ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS IN THE LATER WED NIGHT OR THURSDAY TIME FRAME.
GIVEN THE LARGE SPREAD IN THE ENSEMBLES, DIDN'T SEE ANY
COMPELLING REASONS TO STRAY FROM NBM POPS WHICH DO HAVE HIGH END
CHANCE/LOW END LIKELY POPS LATE WED NIGHT OR THURSDAY.
A TREND TOWARD COOLER, MORE SEASONABLE TEMPERATURES IS EXPECTED
DURING THE SECOND HALF OF THE UPCOMING WORK WEEK.
IZZI/DK
AVIATION /00Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 616 PM CDT SAT MAY 31 2025
NO MAJOR FORECAST CONCERNS ARE EXPECTED AT THE TERMINALS AS A
WEAK SURFACE HIGH WILL REMAIN OVERHEAD. THE ONGOING 10-12 KT
NORTHEAST WINDS WILL EASE OVER THE NEXT 1-2 HOURS RESULTING IN
LIGHT AND VARIABLE WINDS OVERNIGHT. DIRECTIONS WILL RESUME FROM
A EAST-NORTHEAST DIRECTION AT THE CHICAGO TERMINALS AND GYY
SUNDAY AFTERNOON BEHIND A LAKE BREEZE WITH SPEEDS INCREASING
SLIGHTLY INTO THE 6-8 KT RANGE. ELSEWHERE, WINDS WILL REMAIN
LIGHT (AROUND 5 KTS) OUT OF THE NORTHWEST. OTHERWISE, EXPECT
VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD WITH HAZY SKIES
COURTESY OF CANADIAN WILDFIRE SMOKE BUT NO SURFACE IMPACTS
EXPECTED.
YACK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
VISIT US AT WEATHER.GOV/CHICAGO
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page