997
FXUS63 KILX 200757
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
257 AM CDT SUN APR 20 2025
KEY MESSAGES
- THERE IS A LEVEL 2 OF 5 (SLIGHT) RISK FOR SEVERE WEATHER TODAY.
ALL SEVERE HAZARDS ARE IN PLAY (TORNADOES, DAMAGING WINDS, LARGE
HAIL). MOST LIKELY TIMING WOULD BE 6PM TO MIDNIGHT.
- THUNDERSTORMS THIS EVENING MAY ALSO PRODUCE TORRENTIAL RAIN. IF
THERE IS TRAINING OF STORMS, LOCALIZED FLASH FLOODING MAY
OCCUR. THE GREATEST RISK WILL BE NEAR AND WEST OF ROUGHLY I-55.
- ABOVE NORMAL TEMPERATURES ARE EXPECTED THIS WEEK BEGINNING ON TUESDAY.
HIGHS WILL BE IN THE 70S TO NEAR 80 AND LOWS IN THE 50S TO LOW
60S.
DISCUSSION
ISSUED AT 257 AM CDT SUN APR 20 2025
TODAY A LOW PRESSURE SYSTEM IS GOING TO BE LIFTING FROM THE SOUTHERN
PLAINS NORTHEASTWARD INTO THE GREAT LAKES. THE COLD FRONT THAT
SAGGED THROUGH YESTERDAY WILL LIFT BACK NORTH THIS MORNING AS A WARM
FRONT. BY LATE AFTERNOON, THE ASSOCIATED COLD FRONT WILL PUSH
EASTWARD ACROSS ILLINOIS. THESE FRONTAL PASSAGES WILL BRING
ADDITIONAL SHOWERS AND THUNDERSTORMS (SOME POTENTIALLY SEVERE) TO
CENTRAL AND SOUTHEASTERN IL. BY MONDAY AFTERNOON, A HIGH PRESSURE
SYSTEM WILL SET UP OVER THE MIDWEST, GIVING US A SHORT BREAK FROM
THE WET WEATHER. SEVERAL PUSHES OF SHORTWAVE ENERGY WILL ALLOW THE
RAINY/STORMY WEATHER TO RETURN TO THE AREA FOR THE LATTER HALF OF
THE WEEK. THERE IS A SLIGHT RISK (LEVEL 2 OF 5) TODAY FOR OUR
SOUTHWEST COUNTIES. THE MARGINAL RISK (LEVEL 1 OF 5) STRETCHES AS
FAR EAST AS THE I-57 CORRIDOR.
THE WARM FRONT WILL BEGIN TO LIFT OVER THE AREA THIS MORNING AFTER
12Z. THIS WILL RETURN THE CHANCES FOR SOME SCATTERED SHOWERS AND
THUNDERSTORMS THROUGH 20Z. A COUPLE HUNDRED J/KG AND 50-60 KNOTS OF
0-6KM BULK SHEAR IN THE REGION OF THE WARM FRONT MAY ALLOW FOR SOME
OF THE STORMS TO BE ON THE STRONGER SIDE OF THINGS, IF THEY CAN
BREAK THROUGH THE WEAK CAP IN PLACE. HOWEVER, THE HEALTHIER CAPE
VALUES ARE FOUND IN THE WARM SECTOR. IF STORMS ARE ABLE TO FIRE
ALONG ANY OUTFLOW BOUNDARIES OF EXISTING THUNDERSTORMS IN THIS
REGION, WE COULD SEE SOME SEVERE STORMS DEVELOP. THE CLOSER THESE
STORMS ARE TO THE WARM FRONT, THE MORE TORNADIC POTENTIAL THEY WILL
HAVE, WITH 0-3KM SRH OF 600-700 M^2/S^2. THIS FIRST ROUND OF SEVERE
POTENTIAL IS FOCUSED MAINLY EAST OF THE I-57 CORRIDOR.
THE MAIN SHOW OF THE DAY COMES LATER IN THE EVENING, STARTING AT
ABOUT 00Z MONDAY (7PM TONIGHT). THE COLD FRONT WILL PUSH EAST OVER
THE AREA, BRINGING A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS
ALONG WITH IT. WE ARE MOSTLY CONCERNED WITH THIS LINE HAVING
DAMAGING WINDS AND MARGINALLY SEVERE HAIL, BUT THE ISOLATED TORNADO
CANNOT BE COMPLETELY RULED OUT. SOME FORECAST SOUNDINGS ARE SHOWING
AN INVERTED V SIGNATURE FOR MID AFTERNOON INTO EARLY EVENING,
SUPPORTING STRONG WINDS. LONG, SKINNY CAPE PROFILES AND PWATS OF
AROUND 1.5 CAN ALSO BE SEEN ON THESE FORECAST SOUNDINGS, WHICH CAN
SUPPORT HEAVY (MAYBE EVEN TORRENTIAL) RAINFALL IN THESE STORMS.
THERE IS A LOCALIZED FLASH FLOODING RISK WHERE THE HEAVIER RAINFALL
OCCURS. AS THIS LINE MOVES EAST, IT WILL MOVE INTO A LESS FAVORABLE
ENVIRONMENT AND WILL GRADUALLY DECAY AS IT EXITS INTO INDIANA.
BEHIND THE FRONT, SOME GUSTY SOUTH WINDS WILL PUSH THROUGH MONDAY
AFTERNOON. WIND GUSTS AS HIGH AS 35-40 MPH AT TIMES. BY 00Z TUESDAY,
WINDS WILL HAVE SHIFTED OUT OF THE WEST AND WILL BEGIN TO CALM DOWN
AS THE HIGH PRESSURE SETTLES IN.
SEVERAL MORE ROUNDS OF RAIN FOR THE SECOND HALF OF THE WEEK ARE
POSSIBLE, RESULTING FROM SOME DISTURBANCES PASSING OVERHEAD.
TEMPERATURES WILL REMAIN ABOVE NORMAL FOR MUCH OF THE WEEK WITH
HIGHS ON TUESDAY (AND BEYOND) WILL BE IN THE 70S TO NEAR 80 AND LOWS
IN THE 50S TO LOW 60S.
COPPLE
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1207 AM CDT SUN APR 20 2025
AS A WARM FRONT LIFTS NORTHWARD OVERNIGHT, WINDS WILL TREND TOWARD
THE EAST/SOUTHEAST BY EARLY MORNING AND BECOME FAIRLY GUSTY
THROUGH THE REST OF THE FORECAST PERIOD (MAINLY 20-25 KNOTS). A
LOWERING OF CEILINGS IS EXPECTED TO ACCOMPANY THE PASSAGE OF THIS
FEATURE, AND CHANCES OF MVFR CONDITIONS ARE HIGH (>80%) FOR ABOUT
3-5 HOURS AROUND MIDDAY INTO MID AFTERNOON.
GETTING INTO THE EVENING, A LINE OF SHOWERS AND THUNDERSTORMS WILL
QUICKLY MOVE EASTWARD, GENERALLY IN THE 02-05Z TIME FRAME, THOUGH
THE INTENSITY WILL WANE AS IT GETS CLOSE TO THE INDIANA BORDER.
AHEAD OF THIS LINE, A STRONG LOW LEVEL JET AROUND 50 KNOTS WILL
SET UP OVER EASTERN ILLINOIS, AND LLWS HAS BEEN INTRODUCED FOR
KBMI/KDEC/KCMI.
GEELHART
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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