039
FXUS63 KLOT 301904
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
204 PM CDT MON MAR 30 2026
KEY MESSAGES
- SCATTERED THUNDERSTORMS TONIGHT (40-50% CHANCE) WITH SOME
STORMS POSSIBLY SEVERE WITH DAMAGING WINDS AND LARGE HAIL.
- SCATTERED THUNDERSTORMS TUESDAY AFTERNOON/TUESDAY NIGHT WITH
SOME STORMS POSSIBLY SEVERE IN THE AFTERNOON/EVENING, AHEAD OF
A STRONG COLD FRONT/RAPID TEMP DROP.
- AN ACTIVE PATTERN WILL CONTINUE THROUGH SATURDAY WITH PERIODS
OF SHOWERS AND THUNDERSTORMS.
DISCUSSION
ISSUED AT 204 PM CDT MON MAR 30 2026
HIGH TEMPS ARE EXPECTED TO TOP OUT IN THE MID/UPPER 70S THIS
AFTERNOON WITH A FEW LOCATIONS TAGGING 80. SOUTHWEST WINDS MAY
INCREASE FURTHER THROUGH SUNRISE, PERHAPS WITH GUSTS INTO THE 35
MPH RANGE. AS LOW LEVEL WINDS INCREASE THIS EVENING AND SURFACE
TEMPS ONLY DROP IN THE LOWER 60S TONIGHT, THE LOW LEVELS WILL
LIKELY STAY PARTIALLY MIXED, ALLOWING FOR GUSTS OVERNIGHT IN THE
MID/UPPER 20 MPH RANGE AT TIMES.
AN UPPER LEVEL WAVE NOW MOVING ACROSS THE CENTRAL PLAINS WILL
MOVE ACROSS THE LOCAL AREA LATER THIS EVENING INTO THE OVERNIGHT
HOURS. THE MODELS DIFFER CONSIDERABLY ON CONVECTION WITH THIS
SYSTEM. THERE IS THE POTENTIAL FOR THUNDERSTORMS TO DEVELOP
ACROSS EAST CENTRAL IA AND THEN MOVE EAST ACROSS THE AREA LATER
THIS EVENING, LIKELY IN A SLOWLY WEAKENING MODE. THERE IS ALSO
THE POSSIBILITY THAT ADDITIONAL THUNDERSTORMS DEVELOP RIGHT
OVER THE LOCAL AREA. WHILE LAPSE RATES AND INSTABILITY ARE
SUFFICIENT FOR STRONG TO LOCALLY SEVERE THUNDERSTORMS, THE
LIMITING FACTOR APPEARS TO BE THE AMOUNT OF MOISTURE IN THE LOW
LEVELS AND WHETHER IT WILL BE HIGH ENOUGH FOR STORM FORMATION.
HRRR/RAP ARE VERY CONSISTENT WITH THUNDERSTORMS DEVELOPING IN
THE LATE EVENING AND MOVING EAST THROUGH THE OVERNIGHT HOURS,
WITH A FOCUS ALONG/NORTH OF I-80. WHILE THERE IS STILL
UNCERTAINTY FOR COVERAGE, HAVE HIGH CHANCE POPS IN THE 40-50%
RANGE FOR THIS POTENTIAL TONIGHT. IF THUNDERSTORMS DEVELOP, THE
STRONGEST STORMS MAY PRODUCE LARGE HAIL AND LOCALLY DAMAGING
WINDS. AND WHILE NIGHTTIME COOLING MAY BE A LIMITING FACTOR, AS
NOTED ABOVE, THE WARMER TEMPS TONIGHT WILL LIKELY KEEP THE LOW
LEVELS PARTIALLY MIXED AND ALLOW FOR ANY STRONGER STORM WIND
GUSTS TO REACH THE SURFACE.
WHILE THE EARLIER TIMING (LATE EVENING/OVERNIGHT) SEEMS TO BE
THE TREND, THERE DOES REMAIN UNCERTAINTY FOR TIMING AND WHETHER
CONVECTION WILL BE ONGOING AT/AFTER DAYBREAK TUESDAY MORNING AND
IF SO, HOW THAT PLAYS INTO PRECIPITATION TRENDS FOR TUESDAY. FOR
NOW HAVE TRENDED POPS LOWER FOR TUESDAY MORNING WHICH THEN
SHOULD ALLOW FOR A DECENT TEMP RECOVERY, WITH TEMPS LIKELY IN
THE LOW/MID 70S BY MIDDAY, EVENTUALLY WARMING FURTHER TO THE
UPPER 70S, POSSIBLY NEAR 80 SOUTH OF I-80.
A STRONG COLD FRONT WILL MOVE ACROSS THE AREA TUESDAY AFTERNOON
THROUGH TUESDAY EVENING, SHIFTING WINDS NORTHERLY, AND
EVENTUALLY NORTHEASTERLY. THIS WILL ALLOW FOR A RAPID TEMP DROP
BEHIND THE FRONT, MOST PRONOUNCED NEAR LAKE MICHIGAN. STILL SOME
UNCERTAINTY FOR THE TIMING OF THIS FRONT BUT MID AFTERNOON FOR
THE CHICAGO METRO/LAKESHORE SEEMS PLAUSIBLE BUT THIS MAY ALSO BE
TOO SLOW. AN EVEN FASTER FROPA COULD IMPACT HIGH TEMPS ACROSS
THE NORTHERN CWA.
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THIS
COLD FRONT TUESDAY AFTERNOON, PERHAPS AS EARLY AS LATE TUESDAY
MORNING, DEPENDING ON TIMING, WITH THE CONVECTION SPREADING
SOUTHEAST ACROSS THE AREA THROUGH THE AFTERNOON INTO THE
EVENING. STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE DURING THIS
TIME PERIOD BUT OVERALL CONFIDENCE FOR SEVERE WEATHER IS LOW AT
THIS TIME WITH THE BEST POTENTIAL LIKELY SOUTH OF I-80. HEAVY
RAIN AND POSSIBLE LOCALIZED FLOODING WILL ALSO BE POSSIBLE
DURING THIS TIME, ALSO LIKELY FOCUSED SOUTH OF I-80. THERE IS
ALSO UNCERTAINTY FOR HOW FAST THIS ACTIVITY WILL MOVE SOUTHEAST
OF THE LOCAL AREA. THE GFS/NAM SHOW ELEVATED CONVECTION
CONTINUING THROUGH WEDNESDAY MORNING AND EVEN SUGGEST IT WILL
SLOWLY LIFT NORTH BACK ACROSS THE AREA. WHILE THIS ACTIVITY MAY
NOT BE HEAVY THUNDERSTORMS, THE POTENTIAL LONG DURATION,
TRAINING AND PERSISTENCE MAY ALSO LEAD TO LOCALIZED FLOODING
CONCERNS.
THERE MAY ALSO BE FOG ALONG/BEHIND THE COLD FRONT TUESDAY
AFTERNOON INTO TUESDAY EVENING AND ESPECIALLY OVER LAKE
MICHIGAN THOUGH CONFIDENCE IS TOO LOW TO ADD MENTION AT THIS
TIME.
CONFIDENCE FOR PRECIP TRENDS/TIMING WEDNESDAY IS RATHER LOW AND
DEPENDENT ON THE TRENDS FROM TUESDAY NIGHT. THE EXPECTATION
WOULD BE FOR THE WARM FRONT TO SLOWLY LIFT BACK NORTH WEDNESDAY
AFTERNOON INTO WEDNESDAY NIGHT, THOUGH THERE IS STILL TIMING
UNCERTAINTY. BUT AS THIS WARM FRONT LIFTS NORTH, PRECIP SHOULD
BE ENDING FROM SOUTH TO NORTH. TOO MUCH UNCERTAINTY FROM THIS
DISTANCE TO TRY TO TIME THIS OUT AND ITS POSSIBLE MUCH OF THE
LOCAL AREA WILL SEE SHOWERS/DRIZZLE AND PERHAPS A FEW STORMS
THROUGH WEDNESDAY AFTERNOON. AFTER MORNING LOWS IN THE 30S FOR
MUCH OF THE AREA, HIGHS MAY ONLY REBOUND INTO THE 40S FOR AREAS
NORTH OF I-80 ALONG WITH BREEZY NORTHEAST WINDS GUSTING INTO THE
MID 20 MPH RANGE.
DEPENDING ON THE OVERALL TIMING OF THE WARM FRONT, ITS POSSIBLE
THAT MUCH OF WEDNESDAY NIGHT COULD END UP BEING DRY WITH TEMPS
WARMING THROUGH THE NIGHT, ESPECIALLY ACROSS THE NORTHERN CWA.
THIS WOULD THEN SETUP A POTENTIALLY WARM THURSDAY WITH HIGHS
BACK AT LEAST IN THE 60S NORTH AND LIKELY 70S SOUTH. THURSDAY
MAY ALSO BE FAIRLY WINDY WITH SOUTHERLY WINDS POSSIBLY GUSTING
INTO THE 30-35 MPH RANGE.
LOW PRESSURE IS EXPECTED TO MOVE JUST NORTHWEST OF THE AREA
THURSDAY AFTERNOON INTO THURSDAY EVENING WITH A COLD FRONT
MOVING ACROSS THE AREA THURSDAY NIGHT. ADDITIONAL THUNDERSTORMS
WILL BE POSSIBLE DURING THIS TIME AND WHILE CURRENTLY NOT
OUTLOOKED, THE POTENTIAL DOES EXIST FOR A FEW STRONG TO POSSIBLY
SEVERE THUNDERSTORMS DURING THIS TIME PERIOD.
THE DAYLIGHT HOURS ON FRIDAY MAY BRING A SHORT LULL IN THE
ACTIVE PATTERN BEFORE ANOTHER STORM SYSTEM MOVES ACROSS THE
REGION BRINGING SHOWERS AND SCATTERED THUNDERSTORMS WITH THE
BEST TIMING FOR THIS ACTIVITY LOOKING TO BE SATURDAY. ANOTHER
COLD FRONT PASSES THE AREA SATURDAY NIGHT WITH A PERIOD OF COOLER
TEMPERATURES THROUGH EARLY NEXT WEEK. CMS
AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 1213 PM CDT MON MAR 30 2026
BROAD SURFACE TROUGHING ACROSS THE CENTRAL UNITED STATES WILL
MAINTAIN SOUTHWESTERLY WINDS (OCCASIONALLY GUSTING ABOVE 25KT)
THROUGH THIS EVENING. TONIGHT, PRESSURE FALLS IN THE GREAT LAKES
WILL FACILITATE THE DEVELOPMENT OF A STRONG SOUTHWESTERLY LOW-
LEVEL JET, WITH 925 TO 850MB FLOW INCREASING TO 50-55 KT. EVEN
WITH MILD SURFACE TEMPERATURES SUPPORTING AT LEAST OCCASIONAL
SURFACE SOUTHWESTERLY GUSTS TO 25KT THROUGH THE NIGHT (MAINLY
AT AT ORD/MDW), LLWS CRITERIA WILL BE MET AT ALL TERMINALS
THROUGH DAYBREAK TUESDAY.
THE OVERARCHING PATTERN TONIGHT THROUGH TOMORROW WILL BE
SUPPORTIVE OF MULTIPLE WAVES OF SHOWERS AND THUNDERSTORMS IN THE
GENERAL REGION.
THE FIRST OPPORTUNITY FOR CONVECTION WILL BE GENERALLY BETWEEN
04-10Z LATE TONIGHT AS AN UPPER-LEVEL VORTICITY MAXIMA
CURRENTLY MOVING ACROSS CENTRAL NEBRASKA SHIFTS EASTWARD AND
ACTIVATES AN EML PLUME STRETCHING ACROSS THE GREAT LAKES.
COVERAGE OF CONVECTION OVERNIGHT WILL DEPEND ON THE DEGREE OF
MOISTENING AT THE BASE OF THE EML, WITH PLAUSIBLE SCENARIOS
RANGING FROM ISOLATED CELLS NEAR THE IL/WI STATE LINE TO AN
OUTRIGHT CONVECTIVE COMPLEX MOVING ACROSS THE TERMINALS.
ENVIRONMENTAL CONDITIONS WILL BE FAVORABLE FOR STRONG WESTERLY
WINDS WITH CONVECTION, ESPECIALLY IF ANY UPSCALE GROWTH OCCURS
(IN WHICH CASE, GUSTS >50KT WOULD BE POSSIBLE). WILL COVER THE
THREAT FOR CONVECTION TONIGHT WITH PROB30 GROUPS AT ALL
TERMINALS WITH AN OPPORTUNITY TO UPGRADE TO TEMPO GROUPS IN
LATER TAF PACKAGES AS TRENDS EMERGE.
THE CONTINUED INTERACTION OF ISENTROPIC ASCENT WITH THE EML
PLUME MAY MAINTAIN CLUSTERS OF THUNDERSTORMS AFTER DAYBREAK,
PARTICULARLY NEAR DPA/ORD/MDW/GYY. CONFIDENCE IN CONVECTION
CONTINUING AFTER DAYBREAK IS ON THE LOWER END OF THE SPECTRUM,
WITH A COMPLETELY DRY SCENARIO BEING EQUALLY PLAUSIBLE. WILL GO
AHEAD AND INTRODUCE PROB30 GROUPS AT ALL BUT RFD THROUGH 17Z. AM
CAUTIOUSLY OPTIMISTIC THAT THERE WILL BE A BREAK IN CONVECTION
DURING THE EARLY AFTERNOON HOURS BEFORE ANOTHER UPPER-LEVEL
WAVE RIDES INTO THE REGION TOWARD THE END OF THE TAF PERIOD AND
ENCOURAGES NEW CONVECTIVE DEVELOPMENT. WINDS TOMORROW WILL BE
SOUTHWESTERLY WITH OCCASIONAL GUSTS IN EXCESS OF 20 KT,
AT ORD/MDW, A LAKE-ENHANCED FRONT WILL SHIFT ACROSS THE
TERMINALS DURING THE LAST 6 HOURS OF THE TAF PERIOD BRINGING A
NORTHEASTERLY WIND SHIFT AND IFR TO MVFR CIGS.
BORCHARDT
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 AM TUESDAY TO 7 PM CDT WEDNESDAY
FOR THE IL AND IN NEARSHORE WATERS.
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