021
FXUS63 KILX 201744
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1244 PM 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.
UPDATE
ISSUED AT 831 AM CDT SUN APR 20 2025
LATEST WPC SURFACE ANALYSIS SHOWS A STATIONARY FRONT EXTENDING FROM
SOUTHERN MISSOURI THROUGH SOUTHERN IL AND EASTWARD ACROSS THE OHIO
VALLEY. NORTH OF THIS FRONT, A TIGHTENING GRADIENT BETWEEN THE
DEVELOPING LOW PRESSURE ACROSS THE SOUTHERN PLAINS AND A SURFACE
HIGH ANCHORED OVER THE GREAT LAKES HAS RESULTED IN SUSTAINED
EASTERLY WINDS AROUND 20 MPH. IN ADDITION, TEMPERATURES REMAIN IN
THE LOW TO MID 50S AS PERIODS OF ELEVATED SHOWERS AND A COUPLE
THUNDERSTORMS ROLL THROUGH THE AREA DUE TO ISENTROPIC UPGLIDE ON THE
NOSE OF A WEAK LLJ. CAMS ARE IN GENERAL AGREEMENT THE WARM FRONT
WILL LIFT NORTH THROUGH THE AREA LATE THIS MORNING THROUGH THE
AFTERNOON (REACHING ROUGHLY I-80 BY MID EVENING) TO PROVIDE AN END
TO MOST OF THE SHOWER ACTIVITY; PORTIONS OF THE AREA, ESPECIALLY
NEAR AND EAST OF THE I-57 CORRIDOR, MIGHT EVEN SEE THE SUN BRIEFLY
THIS AFTERNOON. INGESTING CURRENT RADAR AND SATELLITE OBSERVATIONS,
THE CAMS CONTINUE THEIR WESTWARD SHIFT WITH CONVECTION AND SLOWER
ARRIVAL TIME FOR THE ILX CWA (VS WHAT THEY WERE SHOWING YESTERDAY),
GENERALLY SUGGESTING A LOWER SEVERE WEATHER THREAT FOR MOST OF THE
ILX CWA. NONETHELESS, THE STRONG KINEMATICS FIELDS WITH THIS LOW
LEAVE A FEELING OF CONCERN FOR DAMAGING STRAIGHT-LINE WIND GUSTS AND
QLCS TORNADOES MAINLY NEAR AND WEST OF A JACKSONVILLE TO LACON LINE.
EVEN FURTHER EAST, THE 55-70 KT 850MB LLJ SHIFTING OVERHEAD
THROUGHOUT THE NIGHT (EVEN AS STORMS ARE FALLING APART DUE TO WANING
INSTABILITY) GIVES A FEELING OF UNEASE, AS ANY STRONGER DOWNDRAFTS
MIGHT BE ABLE TO MIX SOME DAMAGING GUSTS DOWN TO THE SURFACE.
BUMGARDNER
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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1241 PM CDT SUN APR 20 2025
AS STORMS LIFT NORTH AND OUT OF CENTRAL IL EARLY THIS AFTERNOON,
OUR MAIN FORECAST CONCERN BECOMES PESKY BKN CEILINGS BETWEEN FL020
AND FL040 WHICH STRADDLES THE MVFR FLIGHT CATEGORY. HREF SUGGESTS
PROBABILITIES DECREASE FROM SOUTH TO NORTH AS THE WARM FRONT
LIFTS NORTHWARD THROUGH THE AREA OVER THE NEXT SEVERAL HOURS.
THE NEXT CONCERN IS A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS
WHICH WILL BRING GUSTY WINDS AS IT SWEEPS WEST TO EAST ACROSS THE
TERMINALS BETWEEN ROUGHLY 01Z AND 06Z. FOR THIS A PROB30 GROUP WAS
USED TO MENTION THE THUNDER POTENTIAL, AS WELL AS ERRATIC WIND
GUSTS TO 40-45 KT. AHEAD OF THOSE STORMS, A SHORT PERIOD OF LLWS
IS EXPECTED AS A STRENGTHENING LLJ INCREASES EAST-SOUTHEAST WINDS
TO 50 KT AROUND FL020.
BEHIND THAT LINE OF STORMS AND THEIR ASSOCIATED COLD FRONT, A DRY
SLOT MAY BRING A BRIEF END TO THE LOW CLOUDS, BUT GUIDANCE
ADVERTISES HIGH CONFIDENCE (70%+ CHANCE) IN MVFR OR LOWER CEILINGS
AS WRAP AROUND MOISTURE ENTERS THE PICTURE A FEW HOURS LATER. IN
ADDITION, WINDS BEHIND THE FRONT WILL SWITCH AROUND TO
SOUTHWESTERLY AND MAY CONTINUE TO GUST OVER 25 KT THROUGH THE
NIGHT AND INTO MONDAY MORNING.
BUMGARDNER
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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