038
FXUS63 KLOT 200513
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1213 AM CDT MON APR 20 2026
KEY MESSAGES
- FROST/FREEZE CONDITIONS ARE EXPECTED OUTSIDE OF CHICAGO LATE
TONIGHT INTO MONDAY MORNING.
DISCUSSION
ISSUED AT 255 PM CDT SUN APR 19 2026
CONVECTIVE SHOWERS TIED TO BOTH A SHARP MID-LEVEL TROUGH AND
SURFACE COLD FRONT HAVE PRODUCED RAIN, SNOW, GRAUPEL AND SOME
LIGHTNING ACROSS ACROSS NORTHERN ILLINOIS OVER THE PAST COUPLE
HOURS. THE INTENSITY OF THESE SHOWERS SHOULD CONTINUE THROUGH
LATE AFTERNOON AS THEY TRACK SOUTHEAST BEFORE WANING WITH THE
LOSS OF DAYTIME HEATING.
A BROAD SURFACE HIGH WILL THEN EDGE SOUTHEASTWARD OVER THE AREA
OVERNIGHT INTO MONDAY MORNING. BESIDE A LOW CHANCE FOR SOME
SHALLOW LAKE EFFECT CLOUDS DRIFTING OVER FAR NORTHEAST ILLINOIS
OVERNIGHT, MOSTLY CLEAR TO CLEAR SKIES ARE EXPECTED. VERY DRY
AIR HIGHLIGHTED BY CURRENT DEW POINTS IN THE MID TEENS OVER
CENTRAL WISCONSIN AND PWATS UNDER 0.25 INCH COMBINED WITH
LIGHT/CALM WINDS WILL ALLOW FOR EFFICIENT RADIATIONAL COOLING
TONIGHT. THE CURRENT FREEZE WARNING FOR ALL BUT CENTRAL COOK
COUNTY REMAINS ON TRACK. HAVE OPTED TO ALSO INCLUDE A FROST
ADVISORY FOR CENTRAL COOK COUNTY FOR MAINLY THE NEAR WEST
SUBURBS. IT IS POSSIBLE THAT THE DRY AIR LIMITS FROST
DEVELOPMENT EVEN WITH TEMPS IN THE 32-35F RANGE, BUT IT SEEMS
PRUDENT TO INCLUDE A HEADLINE AS WE ARE NOW WELL INTO THE
GROWING SEASON.
THE HIGH PRESSURE WILL BRING MOSTLY SUNNY SKIES, LIGHT WINDS
AND HIGH TEMPS IN THE 50S (40S NEAR THE LAKE) FOR MONDAY.
INCREASING SOUTHWEST FLOW BEHIND THE DEPARTING RIDGE WILL YIELD
MUCH WARMER CONDITIONS WITH HIGHS IN THE 70S ON TUESDAY.
HOWEVER, A BACKDOOR COLD FRONT BELOW A SMALL MID-LEVEL WAVE
CROSSING THE AREA LATE TUESDAY AFTERNOON INTO THE EVENING MAY
PROVIDE SUFFICIENT ASCENT TO GENERATE AN AXIS OF SHOWERS AND
PERHAPS A FEW STORMS. SOMEWHAT LIMITED LOW-LEVEL MOISTURE AND
EXISTING CAPPING UNDER THE EDGE OF AN EML SHOULD LIMIT
THUNDERSTORM COVERAGE.
RIDGING WILL BUILD BACK INTO THE AREA BY THURSDAY, WITH ANOTHER
ROUND OF SHOWERS AND STORMS, SOME POTENTIALLY STRONG, THURSDAY
NIGHT AND FRIDAY.
KLUBER
AVIATION /06Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 1213 AM CDT MON APR 20 2026
LIGHT AND VARIABLE WINDS WILL GRADUALLY BECOME SOUTHEASTERLY
THROUGH MONDAY MORNING AND THEN SOUTH-SOUTHWESTERLY INTO THE
AFTERNOON. A LAKE BREEZE WILL DEVELOP, BUT IT REMAINS UNCLEAR IF
IT WILL MANAGE TO PUSH THROUGH ORD, MDW, OR GYY PRIOR TO A
GENERAL SYNOPTIC SE WIND SHIFT DURING THE EVENING. AT THIS TIME,
THE CHANCES FOR A NE SHIFT IN THE AFTERNOON ARE THE HIGHEST AT
GYY BUT STILL TOO LOW TO ADD A MENTION IN THE OUTGOING 06Z TAFS.
AFTER ABOUT 00-01Z, WINDS SHOULD TURN SSE/SE AT ALL TERMINALS.
THROUGH LATE MONDAY EVENING AND INTO TUESDAY MORNING, WINDS WILL
RETURN OUT OF THE S TO SSW, WITH OCCASIONAL GUSTS DEVELOPING,
MAINLY AT ORD, MDW, AND POSSIBLY GYY. A MENTION OF LLWS WILL
PROBABLY BE NEEDED AT RFD AND POSSIBLY DPA AFTER ABOUT 06Z, JUST
BEYOND THE END OF THE CURRENT TAFS.
CARLAW
LOT WATCHES/WARNINGS/ADVISORIES
IL...FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR ILZ003-ILZ004-
ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-
ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-ILZ103-ILZ105-
ILZ106-ILZ107-ILZ108.
FROST ADVISORY UNTIL 9 AM CDT THIS MORNING FOR ILZ104.
IN...FREEZE WARNING UNTIL 9 AM CDT /10 AM EDT/ THIS MORNING FOR
INZ001-INZ002-INZ010-INZ011-INZ019.
LM...NONE.
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