848
FXUS63 KLOT 212327
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
627 PM CDT SAT MAR 21 2026
KEY MESSAGES
- MILD WEATHER CONTINUES THIS EVENING, BUT A COLD FRONTAL
PASSAGE EARLY SUNDAY MORNING WILL RESULT IN BLUSTERY AND
SHARPLY COLDER AND CLOUDY CONDITIONS FOR SUNDAY.
- COOLER WEATHER PERSISTS ON MONDAY, BEFORE TEMPERATURES
MODERATE INTO MIDWEEK.
DISCUSSION
ISSUED AT 200 PM CDT SAT MAR 21 2026
MID AND HIGH LEVEL CLOUD COVER WILL CONTINUE TO CLEAR THE AREA
THIS AFTERNOON, FOSTERING A MAINLY SUNNY AFTERNOON. TEMPERATURES
THIS AFTERNOON WILL TOP OUT WELL INTO THE 70S, IF NOT THE LOW
80S (IN SOME AREAS) AS BREEZY SOUTHWESTERLY LOW-LEVEL FLOW
DEVELOPS IN RESPONSE TO THE COMPACT SURFACE LOW TRACKING INTO
NORTHERN WI. CONDITIONS WILL ALSO WARM THROUGH THE AFTERNOON
ALONG THE LAKE MICHIGAN SHORE AS THE FLOW SHIFTS SOUTHWESTERLY.
THESE UNSEASONABLY MILD CONDITIONS WILL PERSIST TONIGHT, BUT
WILL COME TO A QUICK END EARLY SUNDAY MORNING AS A STRONG COLD
FRONT DROPS SOUTH ACROSS THE AREA. IN ADVANCE OF THIS FRONT,
TEMPERATURES WILL HOVER IN THE UPPER 50S TO THE LOW 60S FOR MOST
OF TONIGHT. HOWEVER, WITH THE FRONTAL PASSAGE AROUND, OR A BIT
BEFORE DAYBREAK SUNDAY MORNING, A MUCH COLDER LOW-LEVEL AIRMASS
WILL BE DRIVEN IN OFF OF LAKE MICHIGAN ON GUSTY (30-35 MPH)
NORTH-NORTHEASTERLY WINDS. THE RESULT WILL BE QUICKLY FALLING
TEMPERATURES INTO THE 40S SUNDAY MORNING (AFTERNOON) ALONG AND
NORTH (SOUTH) OF THE ILLINOIS AND KANKAKEE RIVERS. ONCE
TEMPERATURES DO DROP, DO NOT EXPECT MUCH IF ANY RECOVERY SUNDAY
AFTERNOON. IN FACT, THE PRESENCE OF A CONTINUAL FEED OF COLDER
AIR OFF OF LAKE MICHIGAN ALONG WITH AN EXTENSIVE POST FRONTAL
LOW-LEVEL STATUS DECK WILL HOLD TEMPERATURES FAIRLY STEADY IN
THE 40S SUNDAY AFTERNOON (LOW 40S NEAR THE LAKE). THE
POSSIBILITY ALSO EXISTS FOR SOME SCATTERED POST FRONTAL SHOWERS
DURING THE DAY.
THE COOLER WEATHER WILL PERSIST ON MONDAY AS A SURFACE HIGH
SHIFTS INTO THE WESTERN GREAT LAKES. ACCORDINGLY, HIGH
TEMPERATURES ARE GENERALLY EXPECTED TO BE IN THE 40S (COOLEST
NEAR THE LAKE). THE MAIN DIFFERENCES FROM SUNDAY'S WEATHER WILL
BE THE LIGHTER NORTHEASTERLY WINDS AND LESS CLOUD COVER FOR THE
DAY MONDAY.
BROAD WNW MID AND UPPER-LEVEL FLOW WILL TAKE HOLD ACROSS THE
REGION NEXT WEEK. THIS WILL RESULT IN A SERIES OF WEATHER
DISTURBANCES AND ASSOCIATED SURFACE COLD FRONTS CROSSING THE
GREAT LAKES REGION DURING THE MIDDLE AND LATER PART OF NEXT
WEEK. IN ADVANCE OF THESE FRONTS, CONDITIONS WILL WARM BACK WELL
INTO THE 50S ON SOUTHWESTERLY LOW-LEVEL WINDS ON TUESDAY.
THEREAFTER, MILD WEATHER DOES LOOK TO PERSIST TO SOME DEGREE FOR
WEDNESDAY AND THURSDAY. HOWEVER, A COUPLE OF COLD FRONTS MAY
SHIFT INTO THE AREA. THE FIRST MAY SHIFT INTO NORTHERN PARTS OF
THE AREA ON WEDNESDAY BEFORE STALLING JUST SOUTH OF THE LAKE. IF
THIS OCCURS, ONSHORE FLOW NORTH OF THE BOUNDARY WOULD BE LIKELY
TO PROMOTE COOLER CONDITIONS THAN CURRENTLY FORECAST FOR
WEDNESDAY, PARTICULARLY ACROSS NORTHEASTERN IL. OTHERWISE,
TEMPERATURES COULD EASILY MAKE A RUN BACK AROUND 60F FOR
WEDNESDAY. THURSDAY COULD THEN END UP BEING THE WARMEST DAY NEXT
WEEK AS A LOW-LEVEL THERMAL RIDGE ADVECTS OVER THE AREA IN
ADVANCE OF THE NEXT APPROACHING COLD FRONT. THIS SECOND COLD
FRONT LOOKS TO BE MORE SUBSTANTIAL THAN WEDNESDAY'S.
ACCORDINGLY, TEMPERATURES ARE EXPECTED TO TREND BACK DOWN INTO
THE 40S AND LOW 50S ON BREEZY NORTHEASTERLY WINDS AT THE END OF
THE WEEK.
GENERALLY DRY WEATHER IS EXPECTED THROUGH THE PERIOD, WITH ONLY
SOME LOW (20-30%) CHANCES OF PRECIPITATION SUNDAY, AND AGAIN
THURSDAY.
KJB
AVIATION /00Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 627 PM CDT SAT MAR 21 2026
KEY AVIATION FORECAST MESSAGES FOR THE 00Z TAFS:
- BREEZY SOUTHWEST WINDS DIMINISH EARLY THIS EVENING, WITH A
PERIOD OF LLWS LATE AS A 45 KT WSW LOW LEVEL JET DEVELOPS
ALOFT.
- COLD FRONT PUSHES ACROSS THE TERMINALS EARLY SUNDAY MORNING
WITH A WIND SHIFT TO THE NNE AND BLUSTERY CONDITIONS WITH
GUSTS 25-30 KT THROUGH MUCH OF THE DAY/EVENING.
- BRIEF PERIOD OF IFR CIGS POSSIBLE BEHIND THE FRONT EARLY
SUNDAY, THEN MVFR STRATUS LINGERS THROUGH THE END OF THE
PERIOD. CAN'T RULE OUT SOME PATCHY DZ/-RA, THOUGH LOOKS TO BE
MINIMAL.
SURFACE LOW PRESSURE WAS OVER FAR NORTHERN WI AT 6 PM, TRAILING
A COLD FRONT ACROSS SOUTHERN MN INTO NE. BREEZY SOUTHWEST WINDS
AHEAD OF THE FRONT WAS GUSTING INTO THE 20-25 KT RANGE AT
ISSUANCE TIME, BUT SHOULD EASE WITH SUNSET. A PERIOD OF LLWS IS
LIKELY LATER THIS EVENING/EARLY OVERNIGHT HOWEVER, AS A WSW 45
KT LOW LEVEL JET SHIFTS ACROSS THE AREA, WEAKENING QUICKLY
PREDAWN SUNDAY. THE AFOREMENTIONED COLD FRONT IS EXPECTED TO
PUSH SOUTH ACROSS THE TERMINALS AROUND DAYBREAK SUNDAY MORNING,
WITH A SHARP WIND SHIFT TO THE NNE. THESE WINDS WILL BECOME
BLUSTERY WITH GUSTS 25-30 KTS BY MIDDAY AND PERSISTING INTO
SUNDAY NIGHT BEFORE SLOWLY DIMINISHING.
VFR CONDITIONS WILL PERSIST AHEAD OF THE COLD FRONT, AFTER WHICH
LOW CLOUDS WILL SPREAD INTO THE REGION ON THOSE NNE WINDS. THERE
LOOKS TO BE A PERIOD OF AT LEAST SCT/OCCASIONAL BKN IFR FOR A
FEW HOURS INTO LATE MORNING BEFORE CLOUD BASES RISE INTO LOW-END
MVFR WHICH LOOKS TO LINGER THROUGH THE REST OF THE PERIOD. CAN'T
RULE OUT SOME PATCHY DRIZZLE AT TIMES ESPECIALLY LATER IN THE
AFTERNOON, ALTHOUGH THE PROFILE BECOMES FAIRLY DRY SAVE FOR THE
LOW LEVEL MVFR CLOUD LAYER. WOULD EXPECT ANY PRECIP TO BE LIGHT
AND PATCHY, AND HAVE NOT INCLUDED IN TAFS.
RATZER
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 AM SUNDAY TO 1 PM CDT MONDAY FOR
THE IL NEARSHORE WATERS.
SMALL CRAFT ADVISORY FROM 10 AM SUNDAY TO 4 PM CDT MONDAY FOR
THE IN NEARSHORE WATERS.
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