933
FXUS63 KLOT 301201
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
701 AM CDT SUN MAR 30 2025
KEY MESSAGES
- THERE IS A THREAT FOR SEVERE WEATHER AREAWIDE ON SUNDAY
ESPECIALLY BETWEEN 11 AM AND 5 PM CDT THAT INCLUDES ALL
HAZARDS (DAMAGING WINDS, DAMAGING HAIL, TORNADOES).
- A PERIOD OF BELOW AVERAGE TEMPERATURES IS EXPECTED MONDAY AND
TUESDAY BEFORE ANOTHER STORM SYSTEM (WITH A THREAT FOR SEVERE
WEATHER) ARRIVES ON WEDNESDAY.
DISCUSSION
ISSUED AT 313 AM CDT SUN MAR 30 2025
THROUGH MONDAY:
PRIMARY FORECAST CONCERN REMAINS SEVERE POTENTIAL TODAY.
IN THE SHORT TERM, WIDESPREAD LIGHT RAIN AND DRIZZLE DEVELOPED
LATE SATURDAY EVENING AND IS SLOWLY LIFTING NORTHEAST ACROSS
NORTHEAST IL. THIS IS EXPECTED TO END BY DAYBREAK. THE FRONTAL
BOUNDARY WILL SLOWLY LIFT BACK NORTH, THOUGH ONLY MEDIUM
CONFIDENCE ON HOW FAST THIS OCCURS. WHILE AREAS OF FOG WILL
REMAIN POSSIBLE, ESPECIALLY ALONG THE LAKE MICHIGAN SHORE, LOW
LEVEL WINDS ARE ALREADY IN THE 20-30KT RANGE AND THIS IS LIKELY
KEEPING THE LOW LEVELS MIXED JUST ENOUGH TO PREVENT DENSE FOG,
BUT WILL CONTINUE TO MONITOR TRENDS EARLY THIS MORNING.
AN AREA OF THUNDERSTORMS ACROSS NORTHEAST IA WILL CONTINUE
LIFTING NORTHEAST THROUGH DAYBREAK AND MAY MOVE ACROSS THE FAR
NORTHWEST CWA AND POSSIBLY THE ROCKFORD AREA. THESE STORMS ARE
NOT EXPECTED TO BE SEVERE BUT GUSTY WINDS AND SMALL HAIL WOULD
BE POSSIBLE.
ATTENTION THEN TURNS TO ONGOING CONVECTION MOVING NORTHEAST INTO
WESTERN MO AND HOW THIS ACTIVITY WILL INFLUENCE THE CONVECTIVE
EVOLUTION FOR THE LOCAL AREA LATER TODAY. IT APPEARS THERE ARE
THREE POSSIBLE SCENARIOS. THE FIRST, THE CURRENT CONVECTION
CONTINUES MOVING NORTHEAST AND INTO THE WESTERN HALF OF THE CWA,
PERHAPS WEST OF I-57. WHILE THIS ACTIVITY WOULD LIKELY HAVE
GUSTY WINDS AND SMALL HAIL AND PERHAPS EVEN AN ISOLATED SEVERE
STORM, THIS WOULD HELP STABILIZE THE NORTHERN CWA WITH LATER/NEW
CONVECTION LIKELY ENDING UP ACROSS THE SOUTHEAST HALF OR THIRD
OF THE CWA. CURRENT TIMING WOULD SUGGEST AN ARRIVAL INTO THE
SOUTHWEST CWA IN THE 14Z HOUR AND THEN SPREADING ACROSS THE CWA
THROUGH LATE MORNING. THE HRRR HAS BEEN CONSISTENTLY SHOWING
THIS POSSIBILITY FOR MANY RUNS.
THE SECOND SCENARIO IS THE ACTIVITY ENTERING MO SLOWS AND
WEAKENS AND THEN REIGNITES MIDDAY OVER THE CWA, WHICH WILL WOULD
THEN ALLOW FOR A SEVERE THREAT FURTHER NORTH, INCLUDING MUCH OF
THE CHICAGO METRO. THE RAP AND TO SOME EXTENT THE NAMNEST
SUGGEST THIS POSSIBILITY.
THE THIRD POSSIBILITY, THE ACTIVITY MOVING IN MO WEAKENS/
DISSIPATES AND THIS MORNING IS SOMEWHAT QUIET, UNTIL NEW STORMS
DEVELOP. THIS TOO WOULD BRING THE SEVERE THREAT FURTHER NORTH
AND INTO THE CHICAGO METRO AREA. THE ECMWF HAD BEEN SHOWING THIS
POSSIBILITY FOR SEVERAL RUNS BUT WITH THE 00Z RUN, NOW HAS AT
LEAST ISOLATED ACTIVITY THIS MORNING, MAKING THIS PROBABLY THE
LEAST LIKELY OF THE THREE POSSIBILITIES.
DESPITE THE UNCERTAINTY, THE OVERALL MESSAGE REMAINS THE SAME.
LOW PRESSURE WILL PASS ACROSS THE NORTHERN CWA THIS AFTERNOON,
WITH THUNDERSTORMS EXPECTED, SOME SEVERE, WITH THE HIGHEST
COVERAGE AND BEST SEVERE POTENTIAL, LIKELY SOUTH OF I-80. THE
NEW SPC DAY1 OUTLOOK IS VERY SIMILAR TO THE PREVIOUS DAY2
OUTLOOK. HIGHER CONFIDENCE WILL MATERIALIZE AS TRENDS EMERGE
WITH THE CONVECTION MOVING THROUGH MO THIS MORNING.
ANY STORMS THAT DEVELOP TODAY WILL BE RACING TO THE NORTHEAST
AT 50-60 MPH AND IT APPEARS THE ACTIVITY WILL BE EAST OF THE CWA
BY 22Z-23Z. HAVE ADJUSTED POPS ACCORDINGLY, GOING DRY IN THE
WEST BY LATE AFTERNOON AS A COLD FRONT MOVES ACROSS THE AREA.
AFTER HIGHS IN THE MID/UPPER 60S NORTHWEST, LOWER 70S REST OF
THE AREA TODAY, TEMPS WILL STEADILY DROP TONIGHT WITH LOWS
MONDAY MORNING IN THE LOWER/MID 30S. SOUTHWEST WINDS MAY GUST AS
HIGH AS 35 MPH TODAY, THEN TURN WEST/NORTHWEST BEHIND THE FRONT
AND WHILE SPEEDS/GUSTS WILL DIMINISH SOME BY MONDAY MORNING,
WIND CHILLS MAY BE IN THE 20S FOR MUCH OF THE AREA.
PRECIP TRENDS FOR TONIGHT HAVE STEADILY LOWERED WITH MOST OF THE
MODELS SUGGESTING ONLY A FEW RAIN/SNOW SHOWERS ACROSS THE
NORTHEAST CWA AND HAVE LOWERED POPS TO LOW CHANCE. MUCH OF THE
SOUTHWEST/SOUTHERN CWA MAY END UP DRY. HIGHS ONLY REACH THE MID
40S MONDAY WITH WINDS TURNING OFF LAKE MICHIGAN MONDAY
AFTERNOON. CMS
MONDAY NIGHT THROUGH SATURDAY:
AFTER A CHILLY START TO THE WORK WEEK TEMPERATURES WILL
GRADUALLY MODERATE TOWARD MIDWEEK WHEN MULTIPLE ROUNDS OF
THUNDERSTORMS ARE POSSIBLE LATE TUESDAY NIGHT THROUGH WEDNESDAY,
SOME OF WHICH COULD BE SEVERE.
ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO LIFT ACROSS THE
UPPER MIDWEST TOWARD MIDWEEK WHICH WILL BRING YET ANOTHER PERIOD
OF INCLEMENT WEATHER TO THE LOCAL AREA. GUIDANCE HAS TRENDED
MORE CONSISTENTLY EARLIER WITH THE ONSET OF SHOWERS AND
THUNDERSTORMS, WITH STRONG TO POSSIBLY SEVERE THUNDERSTORMS
MOVING INTO THE AREA AS EARLY AS THE PRE-DAWN HOURS EARLY
WEDNESDAY MORNING (POTENTIALLY IN A WEAKENING PHASE) NEAR AND
WEST OF I-39. THIS COINCIDES WITH WHERE THE STORM PREDICTION
CENTER INTRODUCED A LEVEL 2 OF 5 SEVERE WEATHER THREAT ON DAY
3. ADDITIONAL WAVES OF SHOWERS AND STORMS ARE POSSIBLE THROUGH
THE DAY ON WEDNESDAY. DEPENDING ON THE TIMING OF STORMS EXITING
IN THE MORNING THERE IS A WINDOW FOR ANOTHER ROUND OF STRONG TO
SEVERE STORMS IN THE AFTERNOON AND EARLY EVENING. SIMILAR TO
TODAY'S (SUNDAY) SETUP, GIVEN THE CONDITIONAL NATURE OF THE
SEVERE THREAT, EXPECT UPDATES OVER THE COMING DAYS TO THE
FORECAST.
UNCERTAINTY INCREASES LATE WEEK INTO THE WEEKEND WHEN ANOTHER
SYSTEM IS FORECAST TO MOVE ACROSS THE BROADER REGION, THOUGH
DIFFERENCES IN ITS PLACEMENT REMAIN. FOR NOW NBM RAIN CHANCES
SEEM APPROPRIATE (HIGHEST SOUTH OF I-80) WITH TEMPERATURES
GENERALLY IN THE 50S TO LOWER 60S.
PETR
AVIATION /12Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 700 AM CDT SUN MAR 30 2025
KEY AVIATION MESSAGES:
- GRADUAL IMPROVEMENT IN CIGS TO MVFR AND VSBYS TO VFR THIS
MORNING AS THE FRONT LIFTS BACK TO THE NORTH. WINDS TURN
BREEZY OUT OF THE SSW.
- TWO PRIMARY ROUNDS OF THUNDERSTORMS ARE EXPECTED TODAY, SOME
OF WHICH COULD BE SEVERE. ROUND 1: MID TO LATE MORNING
(~15-18Z) AND ROUND 2: THIS AFTERNOON (~18-22Z).
A STALLED BOUNDARY DRAPED ACROSS NORTHEAST ILLINOIS IS VERY
GRADUALLY LIFTING NORTH OF ALL THE TAF SITES EARLY THIS MORNING
AND SHOULD PUSH THROUGH ORD WITHIN THE NEXT HOUR OR SO
RETURNING WINDS TO A STEADY SSW WITH GUSTS UP TO AROUND 25 KT
EXPECTED TODAY. CEILINGS WILL GRADUALLY IMPROVE BACK TO MVFR
WITH VISIBILITIES RETURNING TO VFR OUTSIDE OF ANY
SHOWERS/STORMS.
STORMS THAT DEVELOPED ACROSS NORTHWEST ILLINOIS ARE CONTINUING
TO PUSH NORTHEAST OF THE TERMINALS INTO WISCONSIN THIS MORNING,
WITH ATTENTION NOW TURNING TO THE NEXT ROUND OF STORMS CURRENTLY
MOVING INTO WEST CENTRAL ILLINOIS OUT OF MISSOURI. THIS
ACTIVITY IS EXPECTED TO LIFT ACROSS THE AREA TOWARD THE MID TO
LATE MORNING HOURS, THOUGH IT HAS SHOWN SOME WEAKENING TRENDS
OVER THE PAST 30-60 MINUTES, WITH PERHAPS A LOCALLY HIGHER
POTENTIAL FOR STORMS WITH THIS ROUND TOWARD RFD. ANY STORMS THAT
DO LIFT THROUGH WOULD BE CAPABLE OF GUSTY WINDS UP TO 30-40KT.
THE AFTERNOON SEVERE WEATHER POTENTIAL (ROUND 2) REMAINS
CONDITIONAL FOR THE CHICAGO AREA TERMINALS AND WILL ULTIMATELY
DEPEND ON THE COVERAGE OF STORMS WITH ROUND 1. MORE
ROBUST/GREATER COVERAGE OF STORMS IN THE MORNING COULD SHIFT THE
BETTER POTENTIAL FOR AFTERNOON STORMS SOUTH OF I-80. HOWEVER,
LESS COVERAGE COULD LEAD TO STRONG TO SEVERE THUNDERSTORMS
DEVELOPING AS FAR NORTH AS THE CHICAGO AREA TERMINALS DURING
THE AFTERNOON. ONLY CHANGE MADE WAS TO MOVE UP THE START AND
END TIMES OF THE TEMPO GROUPS TO 18-21Z.
ONCE AFTERNOON STORMS SHIFT OFF TO THE SOUTHEAST BY THIS
EVENING WINDS WILL TURN WEST AND THEN NORTHWESTERLY OVERNIGHT.
LIGHT WRAP AROUND PRECIPITATION MAY DRIFT INTO NORTHERN ILLINOIS
AFTER 0Z IN THE FORM OF LIGHT SNOW AND DRIZZLE. QUESTIONS
REMAIN AS TO WHETHER THERE WILL BE SUFFICIENT SATURATION THIS
FAR SOUTH SO OPTED TO CONTINUE HOLDING OFF ON A FORMAL PRECIP
MENTION IN THE TAFS FOR NOW.
PETR
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...DENSE FOG ADVISORY UNTIL 10 AM CDT THIS MORNING FOR THE IL
NEARSHORE WATERS.
SMALL CRAFT ADVISORY UNTIL 4 AM CDT TUESDAY FOR THE IL AND IN
NEARSHORE WATERS.
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