337
FXUS63 KLOT 191955
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
255 PM CDT SUN APR 19 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 /18Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 112 PM CDT SUN APR 19 2026
KEY MESSAGES:
- SCATTERED SHOWERS THIS AFTERNOON ALONG WITH GUSTY WEST TO
NORTHWEST WINDS.
- LOW CONFIDENCE IN THE WIND DIRECTION FORECAST FOR ORD AND MDW
TOMORROW.
SCATTERED RAIN SHOWERS ARE ONGOING IN THE AREA AT THE BEGINNING
OF THE TAF PERIOD, THOUGH THE GREATER COVERAGE OF SHOWER
ACTIVITY SHOULD DIMINISH BY 21Z. ISOLATED INSTANCES OF GRAUPEL
AND A ROGUE LIGHTNING STRIKE OR TWO MAY ALSO OCCUR WITH THIS
ACTIVITY.
WINDS WILL REMAIN GUSTY AND OUT OF THE WEST TO NORTHWEST THROUGH
THIS AFTERNOON WITH OCCASIONAL GUSTS AS HIGH AS 30 KTS OR SO
POSSIBLE. A NORTHEASTERLY WIND SHIFT MAY OCCUR THIS EVENING AS A
SURFACE TROUGH PUSHES INLAND OFF OF LAKE MICHIGAN, BUT SURFACE
WINDS AT THIS TIME MAY ALREADY BE QUITE LIGHT. THERE ALSO
REMAINS A LOWER-END CHANCE FOR MVFR CEILINGS TO BE OBSERVED
TONIGHT AFTER THIS WIND SHIFT OCCURS, BUT HAVE MAINTAINED VFR
CONDITIONS IN THE TAFS FOR NOW.
TOMORROW, A LAKE BREEZE IS EXPECTED TO DEVELOP AND IS MORE
LIKELY THAN NOT TO STALL IN CLOSE PROXIMITY TO ORD AND MDW.
THUS, CONFIDENCE IN PRECISE WIND DIRECTION TRENDS AT BOTH OF
THESE TAF SITES REMAINS LOW AT THIS TIME, BUT WIND SPEEDS DO
LOOK LIKE THEY'LL REMAIN AT OR BELOW 10 KTS FOR THE MOST PART
TOMORROW.
OGOREK
LOT WATCHES/WARNINGS/ADVISORIES
IL...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM CDT MONDAY FOR
ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-
ILZ013-ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033-ILZ039-
ILZ103-ILZ105-ILZ106-ILZ107-ILZ108.
FROST ADVISORY FROM 2 AM TO 9 AM CDT MONDAY FOR ILZ104.
IN...FREEZE WARNING FROM MIDNIGHT CDT /1 AM EDT/ TONIGHT TO 9 AM
CDT /10 AM EDT/ MONDAY FOR INZ001-INZ002-INZ010-INZ011-
INZ019.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE IL
AND IN NEARSHORE WATERS.
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