075
FXUS63 KILX 300508
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
1208 AM CDT SUN MAR 30 2025
KEY MESSAGES
- THERE IS A LEVEL 3 OF 5 RISK FOR SEVERE WEATHER SUNDAY. LARGE
HAIL, DAMAGING STRAIGHT-LINE WINDS, AND EVEN TORNADOES ARE ALL
CONCERNS WITH STORMS, ESPECIALLY EAST OF I-55 DURING THE
AFTERNOON AND EVENING.
- SUB FREEZING TEMPERATURES MONDAY NIGHT MAY HARM ANY TENDER, NEWLY
EMERGED VEGETATION. THIS IS ESPECIALLY A RISK NORTH OF THE I-74
CORRIDOR WHERE THERE IS A 30-50% CHANCE FOR A HARD FREEZE.
- THUNDERSTORMS RETURN LATE TUESDAY NIGHT INTO WEDNESDAY. WHILE SOME
SEVERE POTENTIAL WILL EXIST WEDNESDAY, THE MAGNITUDE OF THE
LOCAL RISK IS UNCLEAR AT THIS TIME.
DISCUSSION
ISSUED AT 211 PM CDT SAT MAR 29 2025
WIDESPREAD CLOUD COVER AND ISOLATED TO SCATTERED SHOWERS CONTINUE
THIS AFTERNOON AS SOUTHWESTERLY WARM AIR ADVECTION (WAA) CONTINUES
ACROSS THE PRAIRIE STATE. THIS HAS MAINTAINED TEMPERATURES IN THE
60S BENEATH THE PERSISTENT SHOWERS AND AROUND 70 ELSEWHERE, 10+
DEGREES COOLER THAN YESTERDAY BUT STILL 10-15 DEGREES ABOVE
CLIMATOLOGICAL NORMAL FOR THE END OF MARCH.
MODERATE SOUTHERLY LOW LEVEL FLOW WILL CONTINUE THIS EVENING INTO
THE OVERNIGHT, PREVENTING THE BOUNDARY LAYER FROM DECOUPLING AND
MAINTAINING TEMPERATURES IN THE LOW 60S WITH SOME WARMING POSSIBLE
JUST BEFORE SUNRISE AHEAD OF THE APPROACHING LOW WHICH AT THAT TIME
WILL BE LIFTING INTO EASTERN IOWA. DUE TO THE ARRIVAL OF AN EML
CURRENTLY IN THE SOUTHERN/CENTRAL PLAINS, HREF MEAN BRINGS 700-500MB
LAPSE RATES TO AROUND 7.5-8 DEGC/KM BY THIS TIME, WHICH WILL OFFER
SOME ELEVATED INSTABILITY (MUCAPES AROUND 700-1300 J/KG) AHEAD OF A
DECAYING MCS AND ITS ATTENDANT MCV. CAMS ARE NOT IN AGREEMENT ON THE
PRECISE TRACK AND ARRIVAL TIME OF THAT FEATURE, WHICH LEADS TO
UNCERTAINTY SURROUNDING SEVERE POTENTIAL BOTH DURING THE MORNING AND
LATER IN THE DAY. THINKING IS GUSTY WINDS (35-45 MPH) WILL OCCUR
WITH THAT MCV EVEN IF IT FALLS APART AND PRECIP DISSIPATES, BUT IF
IT HOLDS TOGETHER WE COULD HAVE BOTH MARGINALLY SEVERE WIND AND
SMALL HAIL.
THE STRONGEST WIND SHEAR ASSOCIATED WITH THIS SYSTEM WILL ARRIVE
DURING THE AFTERNOON WITH THE APPROACH OF THE UPPER LEVEL LOW, BUT
THE APPRECIABLE INSTABILITY IS SLATED TO BE ALONG AND EAST OF
WHEREVER THE REMNANT MCV OUTFLOW FROM THE MORNING ACTIVITY LINGERS;
DEPENDING ON THE MODEL OF YOUR CHOICE, THIS COULD BE ANYWHERE FROM
ROUGHLY I-55 TO EAST OF I-57. HREF JOINT PROBABILITIES OF SBCAPE
GREATER THAN 1500 J/KG AND 0-6KM BULK SHEAR > 30 KT ARE GREATEST (60-
80%) EAST OF I-55 AND SOUTH OF ROUGHLY I-72 (I-74 EAST OF CHAMPAIGN)
DURING THE AFTERNOON. THE COMBINATION OF VERY LOW LCLS (HREF MEAN IS
LESS THAN 500M), MODEST WIND SHEAR, AND SEASONABLY STRONG
INSTABILITY IS RESULTING IN 50-80% CHANCES FOR STP >1 NEAR AND SOUTH
OF ROUGHLY THE I-70 CORRIDOR, SUGGESTING A RISK FOR TORNADOES WHICH,
DEPENDING ON STORM MODE, COULD BECOME STRONG (EF2+). TIMING HASN'T
CHANGED MUCH, THOUGH THE 12Z CAMS ARE A LITTLE FASTER AND SUGGEST 2
TO 9 PM WILL BE THE PERIOD OF GREATEST CONCERN.
TOMORROW NIGHT, COOL ADVECTION WILL DROP TEMPS BACK INTO THE 30S
WITH HIGHS ON MONDAY ONLY SLATED TO REACH THE UPPER 40S TO LOW 50S
AREA-WIDE. NBM ADVERTISES 40-80% PROBABILITIES THAT LOW TEMPERATURES
FALL BELOW FREEZING, WITH THE HIGHEST CHANCES NORTH OF ROUGHLY I-74
WHERE THERE'S EVEN A 30-50% CHANCE FOR A HARD FREEZE WHICH MAY HARM
ANY SENSITIVE, NEWLY EMERGED VEGETATION.
ALL ATTENTION THEN TURNS TO THE NEXT SYSTEM, WHICH WILL BRING MUCH
WARMER CONDITIONS, GUSTY WINDS, AND ANOTHER CHANCE FOR SEVERE
WEATHER MIDWEEK. OF COURSE, AT THIS TIME RANGE, THERE ARE
CONSIDERABLE DISPARITIES BETWEEN INDIVIDUAL MODELS AND SUCCESSIVE
ITERATIONS OF THOSE MODELS. WHILE A ROBUST SEVERE WEATHER EPISODE IS
LIKELY TO IMPACT SOME PORTION OF THE OHIO/TENNESSEE VALLEY REGIONS,
UNCERTAINTY SURROUNDS WHETHER SUFFICIENT INSTABILITY WILL MAKE ITS
WAY THIS FAR NORTH TO SUPPORT ANOTHER ROUND OF SEVERE WEATHER FOR
US. THE GREATEST CHANCE IS ONCE AGAIN TARGETING AREAS SOUTH OF I-72
WHERE THE SPC HAS PLACED A 30% DAY 5 (WEDNESDAY) RISK. DEPENDING
ON CLOUD COVER AND CONVECTION, WEDNESDAY WILL BE WARM WITH A
40-60% CHANCE HIGHS EXCEED 75 DEGREES.
IT'S UNCLEAR HOW FAR SOUTH THE FRONTAL BOUNDARY ASSOCIATED WITH THAT
SYSTEM PUSHES LATE WEDNESDAY INTO THURSDAY, AND WHETHER ANOTHER
FEATURE WILL PULL IT BACK NORTHWARD BEFORE THE CLOSE OF THE WORK
WEEK. THIS SUGGESTS WE CANNOT CONFIDENTLY RULE OUT THE POSSIBILITY
OF ADDITIONAL THUNDERSTORMS, ESPECIALLY NEAR AND SOUTH OF I-70; IN
ADDITION, THE TEMPERATURE FORECAST REMAINS LARGELY UNCERTAIN
DURING THIS TIME PERIOD THOUGH LREF MEAN KEEPS US IN THE 60S FOR
HIGHS RIGHT INTO THE WEEKEND.
BUMGARDNER
AVIATION
(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1208 AM CDT SUN MAR 30 2025
CHALLENGING AVIATION FORECAST OVER THE NEXT 24 HOURS WITH NUMEROUS
CATEGORY CHANGES AND SCATTERED CONVECTION, ALL LEADING TO LOWER
FORECAST CONFIDENCE ON THE FINE DETAILS. CURRENTLY IFR CEILINGS
COVER MUCH OF CENTRAL IL, THOUGH JUST WEST OF KPIA-KSPI THE LOW
CEILINGS CLEAR OUT. WITH FLOW IN THE CLOUD BEARING LAYER FROM THE
SOUTH, FEEL THESE SITES WILL BE ON THE EDGE OF IFR CEILINGS
THROUGH SUNRISE. THEN ALL SITES SHOULD RISE TO MVFR DURING THE
MORNING. NEXT ISSUE IS TSRA DEVELOPMENT BETWEEN 17-21Z. HIGH
RESOLUTION MODELS FAVOR INITIATION NEAR THE I-55 CORRIDOR, THEN
TRACK STORMS EAST THROUGH MID AFTERNOON. SO HIGHER CONFIDENCE THAT
TSRA WILL AFFECT KDEC- KCMI AND LOWER CONFIDENCE FARTHER WEST.
STRONG WIND GUSTS AND IFR VISIBILITY WILL BE COMMON WITH THE
STORMS. AFTER THE STORMS CLEAR, A PERIOD OF VFR CONDITIONS IS
LIKELY AT KCMI- KDEC, WHILE SITES FARTHER NORTHWEST WILL STAY
PRIMARILY MVFR. BUT THE MVFR CEILINGS SHOULD EVENTUALLY SPREAD
BACK SOUTHEAST DURING THE EVENING. GUSTY SOUTH-SOUTHWEST WINDS TO
PREVAIL AHEAD OF A COLD FRONT, VEERING WEST-SOUTHWEST BEHIND THE
FRONT, AND WEST- NORTHWEST DURING THE EVENING. GUSTS AROUND 25 KT
WILL BE COMMON THROUGH THE FORECAST.
25
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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