333
FXUS63 KLOT 302054
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
354 PM CDT SUN MAR 30 2025
KEY MESSAGES
- 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 354 PM CDT SUN MAR 30 2025
THUNDERSTORMS HAVE CLEARED MUCH OF THE CWA AS OF 4PM, WITH SOME
LINGERING LIGHTNING STRIKES POSSIBLE IN SHOWERS EAST OF I-57
OVER THE NEXT COUPLE HOURS AS THE COLD FRONT SWEEPS EASTWARD.
SOUTHWEST WINDS WILL VEER NORTHWEST WHILE GUSTING TO 30 MPH
TONIGHT AS MUCH COLDER AIR ARRIVES.
AS A DEFORMATION AXIS ASSOCIATED WITH THE PASSING MID-LEVEL
WAVE BRUSHES FAR NORTHERN ILLINOIS TONIGHT, LIGHT RAIN SHOULD
MIX WITH AND POSSIBLY CHANGE OVER TO NON-ACCUMULATING SNOW FOR A
FEW HOURS BEFORE ENDING BY AROUND SUNRISE MONDAY.
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/KLUBER
AVIATION /18Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 1238 PM CDT SUN MAR 30 2025
KEY AVIATION MESSAGES FOR THE CURRENT TAF PERIOD:
- SCATTERED STORMS ARE EXPECTED THROUGH 21Z, SOME OF WHICH MAY
BECOME SEVERE
- GUSTY SOUTHWEST WINDS THROUGH THE TAF PERIOD, BEFORE A LAKE
BREEZE ARRIVES MONDAY AFTERNOON FOR NORTHEAST WINDS
- MVFR CIGS THROUGH MONDAY MORNING
- BRIEF SHOWERS THAT MAY HAVE SOME SNOW MIXED IN AROUND 06Z
CLOSE TO THE WISCONSIN/ILLINOIS STATELINE
CLOUD COVER HAS BROKEN UP FOR A BRIEF VFR WINDOW THROUGH
18-1830Z. HOWEVER, THE CLEARER SKIES TO THE SOUTH WHICH HAS
ALLOWED FOR DESTABILIZATION IN SOUTHERN ILLINOIS WITH STORMS
STARTING TO DEVELOP. TAFS WERE ISSUED WITH PREVAILING -SHRA AT
THE START, BUT THERE MAY BE A DELAY FOR WHEN SHOWERS ARE
SPECIFICALLY AT TERMINALS. NO CHANGES WERE MADE TO THE TEMPO FOR
CHICAGO TERMINALS WITH 19Z TO 21Z BEING THE MAIN WINDOW FOR
STRONGER SCATTERED STORMS TO PASS OVER TERMINALS, SOME OF WHICH
MAY BE SEVERE. FOR RFD, HOWEVER, IS EXPECTED TO HAVE LOWER
INSTABILITY DROPPING THE PROBABILITY FOR THUNDER BELOW 30
PERCENT. THEREFORE, WITH DECREASED CONFIDENCE IN HAVING THUNDER,
IT WAS KEPT OUT OF THE TAFS AND WILL BE HANDLED TACTICALLY IF IT
DOES MATERIALIZE. AS STORMS PASS OVER TERMINALS, EXPECTED LOWER
CIGS NEAR IFR LEVELS, LOWER VIS FROM HEAVIER RAINFALL, AND
STRONG WIND GUSTS.
AS THE FRONT MOVES THROUGH, OTHER THAN SOME LINGERING SHOWERS
TRAILING BEHIND, DRIER CONDITIONS ARE EXPECTED AFTER 21Z, BUT
THE MVFR CIGS ARE EXPECTED TO REMAIN THROUGH THE EVENING. THERE
IS A SLIM CHANCE FOR SOME LOWERING TO IFR OVERNIGHT, BUT NOT
GENERALLY EXPECTED.
THE SURFACE LOW DRIVING TODAY'S STORMS WILL CONTINUE TO MOVE
EAST-NORTHEAST THROUGH THE NIGHT. MOISTURE WILL WRAP AROUND THE
LOW AND TEMPERATURES WILL DROP. THERE IS A BRIEF WINDOW FOR
SHOWERS, BUT CONFIDENCE WAS FOR TERMINALS CLOSER TO THE
WISCONSIN STATELINE. AS TEMPERATURES DROP, THERE IS A CHANCE FOR
SOME SNOW TO MIX IN FOR A BRIEF WINDOW OF -RASN.
LASTLY, WINDS ARE EXPECTED TO BE OUT OF THE SOUTHWEST THROUGH
MOST TAF PERIODS. GUSTS WILL SLOWLY DIMINISH THROUGH THIS
EVENING, BUT GUSTS AROUND 20 KNOTS ARE CERTAINLY POSSIBLE
THROUGH MONDAY EARLY AFTERNOON. HOWEVER, A LAKE BREEZE IS
EXPECTED TO DEVELOP IN THE MID AFTERNOON. LATER TAF PACKAGES
WILL LIKELY FINE TUNED THE TIMING FOR CLEARING TO VFR AS WELL AS
THE FLIP TO NORTHEAST WINDS FOR CHICAGO TERMINALS.
DK
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM CDT TUESDAY FOR THE IL AND IN
NEARSHORE WATERS.
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