686
FXUS63 KLOT 300813
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
313 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 /06Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 1255 AM CDT SUN MAR 30 2025
KEY AVIATION MESSAGES:
- IFR/LIFR CIGS AND VSBYS PERSIST NORTH OF A STALLED FRONT
EARLY THIS MORNING IN STEADY DZ.
- LOW CONFIDENCE IN WIND TRENDS OVERNIGHT WITH THE FRONT
EXPECTED TO VERY GRADUALLY RETREAT BACK NORTH THROUGH THE
OVERNIGHT HOURS.
- MULTIPLE CHANCES FOR SHOWERS AND STORMS TODAY. ONE EARLY IN
THE MORNING TOWARD RFD, ANOTHER MID-LATE MORNING AREAWIDE, AND
A FINAL ROUND IN THE AFTERNOON.
A STALLED FRONT IS CURRENTLY DRAPED ALONG A LINE FROM ROCKFORD
TO NAPERVILLE TO WHITING, IN EARLY THIS MORNING. AREAS OF
DRIZZLE HAVE DEVELOPED AMIDST WARM AIR ADVECTION ATOP THE
BOUNDARY, WHICH HAS IN TURN LED TO CIGS DROPPING TO LOW-END IFR
TO AT TIMES LIFR ALONG WITH VSBYS DOWN TO IFR (LOWEST IN AREAS
FURTHEST NORTH OF THE BOUNDARY). EXPECT THESE CONDITIONS TO
CONTINUE FOR MUCH OF THE OVERNIGHT HOURS, THOUGH A VERY GRADUAL
IMPROVEMENT MAY BEGIN PRIOR TO DAYBREAK IF THE BOUNDARY LIFTS
NORTH A BIT FASTER THAN CURRENTLY INDICATED IN THE TAFS.
THERE REMAIN CHANCES FOR MULTIPLE ROUNDS OF SHOWERS AND STORMS
TODAY. THE FIRST WILL BE MAINLY TOWARD RFD WHERE THUNDERSTORMS
CURRENTLY OVER CENTRAL IA WILL DRIFT NORTHEAST TOWARD NORTHWEST
ILLINOIS. IT APPEARS THIS ACTIVITY MAY JUST MISS RFD TO THE
NORTH BUT GIVEN IT WILL BE QUITE CLOSE, OPTED TO ADD A PROB30
FOR TSRA THROUGH FROM 11-13Z. FURTHER UPSTREAM THUNDERSTORMS
CURRENTLY OVER OKLAHOMA ARE PROGGED TO LIFT NORTHEAST TOWARD THE
AREA TOWARD MID MORNING. THIS WILL BRING ADDITIONAL CHANCES FOR
ISOLATED TO WIDELY SCATTERED THUNDERSTORMS AREAWIDE IF IT HOLDS
TOGETHER, THOUGH CONFIDENCE IN COVERAGE REMAINS ON THE LOWER
SIDE.
THE AFTERNOON SEVERE WEATHER POTENTIAL REMAINS CONDITIONAL AND
WILL ULTIMATELY DEPEND ON THE MORNING STORMS. 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
LIFTING AS FAR NORTH AS THE CHICAGO AREA TERMINALS DURING THE
AFTERNOON. OPTED TO NOT MAKE ANY MAJOR CHANGES TO BOTH OF THESE
TIME PERIODS FOR NOW.
ONCE AFTERNOON STORMS SHIFT OFF TO THE SOUTHEAST BY THIS
EVENING, 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 HOLD OFF ON A FORMAL
MENTION IN THE TAFS WITH THIS UPDATE.
PETR
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 4 AM CDT
TUESDAY FOR THE IL AND IN NEARSHORE WATERS.
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