837
FXUS63 KLOT 020752
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
252 AM CDT MON JUN 2 2025
KEY MESSAGES
- SMOKE (MOSTLY ALOFT) WILL FILTER SUNSHINE UNTIL CLOUDINESS
ROLLS IN TUESDAY.
- SHOWERS AND THUNDERSTORMS WILL LIKELY OVERSPREAD THE AREA FROM
WEST TO EAST LATE TUESDAY AFTERNOON INTO TUESDAY EVENING.
- COOLER WITH RAIN ON WEDNESDAY, FOLLOWED BY ADDITIONAL PERIODS
OF SHOWERS AND PERHAPS SOME STORMS THURSDAY AND FRIDAY.
DISCUSSION
ISSUED AT 252 AM CDT MON JUN 2 2025
THROUGH TUESDAY NIGHT:
LAST LIGHT GOES TRUE COLOR RGB IMAGERY NICELY DEPICTED THE LARGE
AREA OF SMOKE FROM CANADIAN WILDFIRE BLANKETING MOST OF THE
CENTRAL PORTION OF THE COUNTRY. THE CONCENTRATION OF SMOKE ALOFT
DID DECREASE SOME SUNDAY, BUT SATELLITE IMAGERY SHOWS WHAT
APPEARS TO BE A MUCH DENSE/HIGHER CONCENTRATION SMOKE IN A
ROUGHLY NORTH-SOUTH AXIS NEAR AND WEST OF THE MISSISSIPPI RIVER
EARLY SUNDAY EVENING.
MID LEVEL FLOW WILL CONTINUE TO BACK TO A MORE WESTERLY
DIRECTION TODAY AS MID-UPPER LEVEL RIDGE SHIFTS EASTWARD INTO
THE MIDWEST AND WESTERN GREAT LAKES. THIS SHOULD SHOVE THAT AXIS
OF DENSER SMOKE EASTWARD AND INTO OUR CWA TODAY. NEAR SURFACE SMOKE
CONCENTRATION OUTPUT FROM THE HRRR HAS BEEN TRENDING TOWARD A
LOWER NEAR SFC SMOKE CONCENTRATION TODAY. IN ADDITION, THE HRRR
NEAR SFC SMOKE FORECASTS UPSTREAM HAVE GENERALLY SHOWN A HIGH
BIAS BASED ON VISIBILITY OBSERVATIONS UPSTREAM. SO WHILE SOME
NEAR SFC SMOKE IS POSSIBLE THIS AFTERNOON AND TONIGHT, IT SEEMS
UNLIKELY THAT THE CONCENTRATION WOULD BE ENOUGH TO RESULT IN ANY
SIGNIFICANT VISIBILITY RESTRICTIONS. THE DENSER SMOKE
CONCENTRATION TODAY WILL PROBABLY KEEP TEMPS A COUPLE/FEW
DEGREES COOLER THAN THEY OTHERWISE WOULD HAVE BEEN, BUT LOW TO
MID 80S STILL APPEAR ATTAINABLE.
STRENGTHENING SOUTHWESTERLY FLOW IS EXPECTED IN ADVANCE OF AN
APPROACHING UPPER TROUGH AND ASSOCIATED SFC COLD FRONT TUESDAY.
SOUTHERN STREAM SHORTWAVE IS EXPECTED TO PHASE WITH THE LARGE
NORTHERN STREAM TROUGH AS THEY MOVE EASTWARD TOWARD THE REGION.
RELATIVELY WARM MID LEVEL TEMPERATURES AND SUBSEQUENT WEAK MID
LEVEL LAPSE RATES SHOULD DAMPEN INSTABILITY OUT AHEAD OF THIS
FRONT. BY LATER TUESDAY AFTERNOON, A NARROW AXIS OF MOISTURE
WILL ADVECT NORTHWARD IN ADVANCE OF THE FRONT AND LEAD TO MLCAPE
VALUES NEAR TO MAYBE JUST ABOVE 500 J/KG INTO NORTHWEST IL.
WHILE THERE WILL BE A NOTABLE INCREASE IN MID LEVEL FLOW
ASSOCIATED WITH THE SOUTHERN STREAM SHORTWAVE TROUGH, FAIRLY
UNIDIRECTIONAL FLOW WITH STRONG LOW LEVEL JET SHOULD RESULT IN
ONLY ABOUT 30 KT OF EFFECTIVE SHEAR. GIVEN THE FAIRLY STRONG
LOW-MID LEVEL FLOW, CANNOT RULE OUT A STRONG TO MARGINALLY
SEVERE WIND GUST OR TWO OVER OUR WESTERN CWA LATE TUESDAY
AFTERNOON INTO TUESDAY EVENING, THE WEAK INSTABILITY AND POOR
LOW TO MID LEVEL LAPSE RATES SUGGEST ANY THREAT OF STRONG TO
SEVERE GUSTS SHOULD BE PRETTY LIMITED.
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO GRADUALLY SPREAD
EASTWARD ACROSS OUR CWA TUESDAY NIGHT, BUT WHAT LITTLE BOUNDARY
LAYER BASED INSTABILITY WE CAN MUSTER UP LATER TUESDAY AFTERNOON
SHOULD LARGELY BE GONE AS WE LOSE DIURNAL HEATING. EXPECT THE
THUNDERSTORM COVERAGE AND INTENSITY TO GRADUALLY WANE TUESDAY
NIGHT AS THIS ACTIVITY MOVES ACROSS THE AREA. THERE'S A
PLAUSIBLE SCENARIO WHERE THE COVERAGE OF PRECIPITATION
DIMINISHES CONSIDERABLY TOO AS THE ACTIVITY MOVES INTO EASTERN
PORTIONS OF OUR CWA TUESDAY NIGHT. FOR NOW, DIDN'T MAKE ANY
CHANGES TO NBM POPS (WHICH ARE PRETTY AGGRESSIVE) TUESDAY NIGHT,
SINCE GUIDANCE IS PRETTY INSISTENT ON WIDESPREAD AND FAIRLY
SOAKING RAINFALL ACROSS OUR CWA TUESDAY NIGHT.
- IZZI
WEDNESDAY THROUGH SUNDAY:
THE COLD FRONT ASSOCIATED WITH A LONGWAVE TROUGH OVER NORTHERN
MANITOBA TODAY WILL DRIFT SOUTHEASTWARD ACROSS THE FORECAST AREA
TUESDAY NIGHT INTO WEDNESDAY MORNING, BRINGING PRIMARILY
ANAFRONTAL SHOWERS/RAIN ACROSS THE AREA UNDER MODEST FORCING
WITH THE RIGHT ENTRANCE OF A MID TO UPPER-LEVEL JET. THIS
PATTERN RESEMBLES EARLY FALL MORE THAN EARLY SUMMER, WITH MAX
TEMPS FOR THE CALENDAR DAY WEDNESDAY FOR AT LEAST SOME OF THE
AREA OCCURRING PRIOR TO SUNRISE AHEAD OF THE FRONT. WHEREVER
THE RAIN BAND IS MORE PROMINENT DURING THE DAY, TEMPS SHOULD
HOLD IN THE 60S (50S NEAR THE LAKE).
A TROUGH OVER THE NORTHERN ROCKIES MIDWEEK IS PROGGED TO EITHER
PICKUP OR PARTIALLY SHEAR AN UPPER-LEVEL LOW CURRENTLY OVER THE
DESERT SOUTHWEST. GIVEN THE DISTANCE BETWEEN THE TWO FEATURES,
GUIDANCE NON-SURIPRSINGLY VARIES WITH THE BROADER MID-LEVEL
PATTERN ACROSS THE CENTRAL CONUS THURSDAY INTO FRIDAY. THE
CONSENSUS IS FOR MOST OF THE ENERGY FROM THE SOUTHWEST LOW TO
RESULT IN CYCLOGENESIS ALONG THE STALLED FRONT ACROSS MISSOURI
AND SOUTHERN IL/IN LATE THURSDAY, RESULTING IN A RENEWED CHANCE
OF RAIN OR PERIODS OF SHOWERS WITH SOME STORMS THURSDAY NIGHT
INTO FRIDAY.
BEHIND FRIDAY'S POTENTIAL PRECIP, THE FRONT SHOULD FINALLY
CLEAR THE AREA WELL TO THE SOUTHEAST. A SPRAWLING HIGH PRESSURE
ACROSS THE WESTERN GREAT LAKES THIS WEEKEND SHOULD PRODUCE
SEASONABLE CONDITIONS AND DRY WEATHER SATURDAY AND POSSIBLY
THROUGH SUNDAY.
KLUBER
AVIATION /06Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 1242 AM CDT MON JUN 2 2025
LIGHT S WINDS AT TAF ISSUANCE WILL SETTLE SSW FROM AROUND
SUNRISE THROUGH THE REMAINDER OF THE PERIOD. SPEEDS WILL
INCREASE TO AROUND 10 KNOTS FOR MUCH TODAY AND TONIGHT. A FEW
INFREQUENT GUSTS TO 20 KNOTS CAN BE EXPECTED LATE THIS
AFTERNOON, THOUGH SMOKE ALOFT SHOULD TEMPER MIXING ENOUGH TO
LIMIT GUSTINESS.
CANADIAN WILDFIRE SMOKE FILTERING OVER THE AREA WILL REMAIN
APPARENT THROUGH AT LEAST TONIGHT. UPSTREAM SATELLITE AND
SURFACE OBS OVER EASTERN IOWA SUGGEST THAT A THICKER RIBBON OF
SMOKE WILL CROSS THE TERMINALS TODAY, WITH DAYTIME MIXING
BRINGING DOWN SOME OF THE SMOKE TOWARD THE SURFACE TO PRODUCE
HAZY CONDITIONS THIS AFTERNOON. SOME HAZE MAY PERSIST TONIGHT AS
ANY SMOKE BECOMES TRAPPED IN THE NOCTURNAL INVERSION. AS AN
ADDED NOTE, CLOUDS IN THE CURRENT TAF ARE AN APPROXIMATION OF
THE BASE OF THE MAIN SMOKE LAYER, WITH LITTLE TO NO ACTUAL
CLOUDS EXPECTED OVER THE AREA THROUGH THE PERIOD.
KLUBER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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