892
FXUS63 KLOT 011735
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1235 PM CDT SUN JUN 1 2025
KEY MESSAGES
- WILDFIRE SMOKE FROM CANADIAN FIRES WILL CONTINUE TO FILTER
OVER THE AREA THROUGH MONDAY. MOST OF THIS SMOKE SHOULD REMAIN
ALOFT AND RESULT IN HAZY SKIES, THOUGH SOME SMOKE MAY REACH
THE SURFACE MONDAY AFTERNOON.
- ABOVE AVERAGE TEMPERATURES EXPECTED EARLY NEXT WEEK, WITH
WARMTH RIGHT UP TO THE LAKEFRONT.
- PERIOD OF SHOWERS AND STORMS IS LIKELY LATE TUESDAY THROUGH
EARLY WEDNESDAY TIME FRAME.
- MUCH LOWER CONFIDENCE, BUT A SECOND ROUND OF SHOWERS AND
T-STORMS IS POSSIBLE LATE WEDNESDAY INTO THURSDAY, ESPECIALLY
SOUTHEASTERN CWA.
DISCUSSION
ISSUED AT 310 AM CDT SUN JUN 1 2025
THROUGH MONDAY:
SURFACE HIGH PRESSURE WILL REMAIN CENTERED OVER THE FORECAST
AREA THROUGH THIS EVENING BEFORE SHIFTING TO THE SOUTHEAST ON
MONDAY. LIGHT NORTH WINDS ARE FAVORED TODAY, WITH AN EASTERLY
SHIFT WITH A LAKE BREEZE ACROSS NORTHEAST ILLINOIS AND NORTHWEST
INDIANA THIS AFTERNOON. LIGHT SOUTHEAST WINDS WILL THEN VEER
SOUTHWEST AND INCREASE ON MONDAY.
THE MAIN IMPACT ON SENSIBLE WEATHER WILL REMAIN THE VEIL OF
CANADIAN WILDFIRE SMOKE FILTERING OVER THE REGION. THE SMOKE
SHOULD REMAIN ALOFT THROUGH AT LEAST MONDAY MORNING. HOWEVER,
HIGHER CONCENTRATIONS WILL BEGIN TO ADVECT EASTWARD WITH THE
VEERING FLOW THROUGH THE DAY MONDAY. GUIDANCE HINTS THAT DIURNAL
MIXING MAY BEGIN TO BRING DOWN SOME OF THE SMOKE TO THE SURFACE
IN THE AFTERNOON, SO WILL NEED TO FOLLOW TRENDS AND INTRODUCE
AT LEASE SOME MENTION OF SMOKE IN THE FORECAST WITH SUBSEQUENT
UPDATES. HAZY SKIES WILL PERSIST DURING WHAT WOULD NORMALLY BE A
PERIOD WITH LITTLE CLOUD COVER. ADDITIONALLY, THE PERSISTENT
SMOKE SHOULD SLIGHTLY TEMPER HIGH TEMPS TODAY AND MONDAY, SO
HAVE LOWERED VALUES BY A DEGREE OR TWO AREAWIDE BOTH DAYS.
KLUBER
MONDAY NIGHT THROUGH SATURDAY:
TUESDAY SHOULD BE WINDY AND VERY WARM AHEAD OF THE APPROACHING
UPPER TROUGH AND ASSOCIATED SFC COLD FRONT. CAN'T RULE OUT SOME
SMOKE LINGER INTO TUESDAY, WHICH COULD KEEP HIGH TEMPS A BIT
COOLER. DID SHAVE A FEW DEGREES OFF OF NBM TEMPS TUESDAY IN OUR
WESTERN CWA, WHERE CLOUD COVER AND MAYBE SOME LATE AFTERNOON
SHOWERS AND STORMS COULD MAKE REACHING UPPER 80S A CHALLENGE.
ELSEWHERE, STUCK WITH UPPER 80S OFFERED UP BY THE NBM, BUT LOWER
THAN AVERAGE CONFIDENCE GIVEN THE POTENTIAL FOR CLOUD COVER AND
OR SMOKE KEEPING IT A BIT COOLER.
SHOWERS AND THUNDERSTORMS SHOULD OVERSPREAD THE CWA TUESDAY
NIGHT. NAM INSTABILITY LOOKS OVERDONE DUE TO ITS MOIST BOUNDARY
LAYER BIAS. WEAK MID LEVEL LAPSE RATES AND STUNTED HEATING OF
THE BOUNDARY LAYER SUGGEST THAT INSTABILITY IN OUR AREA SHOULD
BE PRETTY WEAK, LIKELY ONLY PEAKING AROUND 500 J/KG OVER OUR
WESTERN CWA TUESDAY EVENING. CANNOT TOTALLY RULE OUT A LOW END
SEVERE RISK TUE EVENING IN OUR WESTERN CWA, BUT CHANCES LOOK
PRETTY LOW/CONDITIONAL. CONVECTION SHOULD GENERALLY BE IN A
WEAKENING PHASE OVERNIGHT AS IT MOVES IN PROGRESSIVELY LESS
UNSTABLE AIR MASS OVER EASTERN IL AND NORTHWEST IN.
CUT OFF LOW OVER THE DESSERT SOUTHWEST IS STILL PROGGED TO EJECT
OUT AND RIDE THE WEST-SOUTHWESTERLY FLOW IN THE MIDWEST OR LOWER
OHIO VALLEY REGION WEDNESDAY NIGHT INTO THURSDAY. STILL A LOT OF
SPREAD IN GUIDANCE REGARDING HOW FAR SOUTH OF OUR AREA THE
BOUNDARY WILL GET BEFORE STALLING OUT AND POSSIBLY RETREATING
NORTH SOME IN ADVANCE OF THE SHEARING OUT SHORTWAVE. OPERATIONAL
GFS HAS TRENDED TOWARD A MORE SOUTHERLY SOLUTION WITH THE
STALLING OUT OF THE FRONT AND WOULD SUGGEST OUR AREA LARGELY DRY
OUT LATE TUE NIGHT/EARLY WED MORNING AND STAY DRY THE REST OF
THE WEEK. THE 00Z ECMWF STILL STALLS THE BOUNDARY CLOSER TO OUR
CWA, BEFORE LIFTING IT NORTH SLIGHTLY WITH MORE WIDESPREAD
SHOWER AND THUNDERSTORM ACTIVITY. WITH CONSIDERABLE SPREAD IN
THE ENSEMBLES, CONFIDENCE REMAINS ON THE LOWER END OF THE
SPECTRUM. GIVEN THE LOW CONFIDENCE, MADE NO ADJUSTMENTS TO NBM
POPS, WHICH DO FAVOR OUR SOUTHERN CWA WITH HIGHER POPS, WHICH
LOOKS REASONABLE.
DRIER CONDITIONS ARE EXPECTED FRIDAY AND SATURDAY WITH COOLER,
MORE SEASONABLE TEMPERATURES AND WINDS OFF THE LAKE KEEPING
TEMPS COOLER LAKESIDE.
- IZZI
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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