369
FXUS63 KILX 202308
AFDILX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE LINCOLN IL
508 PM CST WED NOV 20 2024
KEY MESSAGES
- OCCASIONAL LIGHT SNOW SHOWERS ARE POSSIBLE TONIGHT (MAINLY I-74
AND NORTH) AND THURSDAY AFTERNOON/EVENING (NORTHEAST OF
BLOOMINGTON TO PARIS). THERE IS A 50-90 PERCENT CHANCE OF MINOR
ACCUMULATIONS NORTHEAST OF A BLOOMINGTON TO PARIS LINE.
- BREEZY CONDITIONS ARE EXPECTED THROUGH THURSDAY NIGHT. WINDS
WILL PEAK THURSDAY AFTERNOON AND EVENING WITH GUSTS IN THE
35-45 MPH RANGE. THERE IS CURRENTLY A 30 PERCENT CHANCE TO
EXCEED 45 MPH.
- TEMPS WILL FALL INTO THE UPPER 20S TO LOWER 30S TONIGHT INTO
THURSDAY MORNING. WIND CHILLS WILL DIP TO 15-20 DEGREES ACROSS
MOST OF CENTRAL ILLINOIS.
DISCUSSION
ISSUED AT 215 PM CST WED NOV 20 2024
THIS AFTERNOON, A BROAD UPPER LEVEL LOW IS NOTED ON WATER VAPOR
IMAGERY SPINNING OVER PORTIONS OF THE UPPER MIDWEST. SEVERAL PIN-
WHEELING VORT LOBES ROTATING AROUND THIS FEATURE WILL BRING PERIODIC
CHANCES FOR LIGHT PRECIP TO PORTIONS OF CENTRAL ILLINOIS REST OF
TODAY AND TOMORROW. A WEAKER, LEAD SHORTWAVE IS MOVING ACROSS
CENTRAL ILLINOIS THIS AFTERNOON. THIS WAVE WILL BE ACCOMPANIED BY
STEEP LOW LEVEL LAPSE RATES WITH WEAK SBCAPE PRESENT THROUGH
TONIGHT. INSTABILITY AND MOISTURE ARE JUST DEEP ENOUGH TO TAP INTO
THE DGZ SUPPORTING A FEW LIGHT RAIN/SNOW SHOWERS BEFORE CHANGING TO
PRIMARILY SNOW LATE THIS EVENING AS TEMPS COOL DOWN. OVERNIGHT,
TEMPS WILL DIP INTO THE UPPER 20S TO LOWER 30S ACROSS CENTRAL
ILLINOIS. CONTINUED BREEZY CONDITIONS WILL RESULT IN WIND CHILL
VALUES IN THE TEENS ACROSS MOST OF CENTRAL ILLINOIS.
ON THURSDAY, MAIN UPPER LOW WILL DIG SOUTHEAST ACROSS THE GREAT
LAKES WITH A TRAILING VORT LOBE DIVING SOUTH INTO NORTHEASTERN
ILLINOIS THURSDAY AFTERNOON INTO THE EVENING. A SURFACE LOW WILL
DEVELOP IN RESPONSE TO THE WAVE PUSHING SOUTH ACROSS LAKE MICHIGAN
THROUGH THE DAY. A TIGHT PRESSURE GRADIENT WILL OVERSPREAD CENTRAL
ILLINOIS AS A RESULT CONTRIBUTING TO STRONG NORTHWESTERLY WINDS
AGAIN, ESPECIALLY DURING THE AFTERNOON AND EVENING. NBM 90TH
PERCENTILE WINDS (INDICATING A REASONABLE TOP END TO THE WIND GUSTS)
ARE GENERALLY 45-50 MPH ACROSS THE AREA. ON THE OTHER HAND, NBM
CONFIDENCE IN EXCEEDING 45 MPH GUSTS (WIND ADVISORY CRITERIA) PEAKS
AT ONLY 30 PERCENT THURSDAY AFTERNOON. WILL FOREGO ANY WIND
HEADLINES AT THIS TIME OWING TO THE LOW CONFIDENCE, BUT A SPORADIC
ADVISORY CRITERIA GUST MAY OCCUR THURSDAY.
MEANWHILE, SNOW REMAINS IN THE FORECAST THURSDAY WITH SOME MINOR
ACCUMULATIONS POSSIBLE, ESPECIALLY NEAR AND NORTH OF A BLOOMINGTON
TO PARIS LINE. A PIN-WHEELING VORT LOBE DIVING SOUTH ACROSS IL/IN
THURSDAY AFTERNOON WILL RESULT IN AN INCREASE IN PRECIP CHANCES
ESPECIALLY ACROSS THE EASTERN HALF OF THE FORECAST AREA. FORECAST
SOUNDINGS FOR CMI SHOW A SHALLOW NEAR SURFACE WARM LAYER THAT WILL
NOT BE SUFFICIENT FOR COMPLETE MELTING WHILE ALOFT, A DEEP LAYER
OF MOISTURE CUTTING THROUGH THE DGZ WILL BE PRESENT ENSURING ICE
CRYSTALS FOR SNOW. GIVEN THE TIME OF DAY, ANY ACCUMULATIONS MAY
BE LIMITED TO THE GRASS OR ELEVATED SURFACES, BUT MINOR
ACCUMULATIONS DO APPEAR POSSIBLE. NBM INDICATES A 50 PERCENT
CHANCE FOR ACCUMULATING SNOW (>0.1 IN) NORTHEAST OF A BLOOMINGTON
TO PARIS LINE WITH THOSE PROBABILITIES INCREASING TO 80 PERCENT
ACROSS VERMILION COUNTY. HIGH-END PROBABILITIES (90TH PERCENTILE)
IS ROUGHLY 1-2 INCHES EAST OF BLOOMINGTON AND ALONG/NORTH OF I-74
IN EAST CENTRAL ILLINOIS.
UPPER LOW WILL SHIFT TO THE EAST COAST FRIDAY WITH STRONG MID LEVEL
HEIGHT RISES OVERSPREADING THE MIDWEST IN ITS WAKE. AT THE SURFACE,
HIGH PRESSURE OVER THE GREAT PLAINS FRIDAY MORNING WILL GRADUALLY
SHIFT EAST ACROSS THE MISSISSIPPI VALLEY FRIDAY AND SATURDAY AND
EVENTUALLY TO THE OHIO VALLEY SUNDAY. THIS WILL SET THE STAGE FOR
FAIR WEATHER TO END THE WEEK AND WILL CONTINUE THROUGH THE WEEKEND.
A GRADUAL WARMING TREND IS ALSO EXPECTED THROUGH THIS TIME FRAME
WITH MID 40S FOR HIGHS FRIDAY WARMING BACK INTO THE MID TO UPPER 50S
SUNDAY AS SOUTHERLY FLOW SPREADS BACK INTO THE REGION BEHIND THE
RIDGE AXIS.
UPPER PATTERN WILL GRADUALLY FLATTEN OUT OVER THE WEEKEND AND BECOME
ZONAL BY EARLY NEXT WEEK. LOW LEVEL BAROCLINIC ZONE WILL BE LAID OUT
WEST-TO-EAST ALONG THE OHIO RIVER VALLEY AND WILL SERVE AS THE FOCUS
FOR PRECIP CHANCES THROUGH THE FIRST HALF OF NEXT WEEK. GUIDANCE HAS
TRENDED FURTHER SOUTH WITH THE POSITION OF THE BOUNDARY WHICH HAS
RESULTED IN SLIGHTLY LOWER POPS ACROSS CENTRAL ILLINOIS.
DEUBELBEISS
AVIATION
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 508 PM CST WED NOV 20 2024
OCCASIONAL -SN/-RA WILL AFFECT TERMINALS NEAR I-74 THIS EVENING
WITH VFR CEILING/VIS. MVFR CEILINGS ARE FORECAST TO WORK IN FROM
THE NORTH OVERNIGHT AND PERSIST THROUGH THURSDAY AFTERNOON. A
STRONGER DISTURBANCE DROPPING SOUTHEAST THROUGH THE LOWER GREAT
LAKES WILL BRING -RASN TO KBMI-KCMI THURSDAY AFTERNOON,
POTENTIALLY DROPPING TO IFR IF PREDOMINANT -SN CAN OVERCOME
MARGINAL LOW LEVEL TEMPERATURES. WEST-NORTHWEST WINDS GUSTING NEAR
25 KT WILL BE COMMON OVERNIGHT, THEN INCREASE NEAR 35 KT BY MIDDAY
AS THE PRESSURE GRADIENT TIGHTENS MORE.
25
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
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