326
FXUS63 KILX 271210
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
610 AM CST WED JAN 27 2021
SYNOPSIS
ISSUED AT 400 AM CST WED JAN 27 2021
LIGHT SNOW WILL SPREAD EASTWARD ACROSS CENTRAL AND SOUTHEAST IL
DURING THIS MORNING, AND DIMINISH TOWARD SUNSET. BETWEEN 1 AND 2
INCHES OF SNOW IS EXPECTED ALONG AND SOUTH OF A RUSHVILLE TO
DECATUR TO TERRE HAUTE LINE TODAY. WINTER WEATHER ADVISORIES ARE
IN EFFECT TODAY FOR SOUTHERN AND SOUTHWEST ILLINOIS. MUCH COLDER
TEMPERATURES WILL ARRIVE TONIGHT WITH LOWS IN THE SINGLE DIGITS TO
TEENS, AND WIND CHILLS OF 5 BELOW TO 5 ABOVE OVER MUCH OF CENTRAL
IL. STRONG CANADIAN HIGH PRESSURE WILL BUILD INTO IL BY THURSDAY
AFTERNOON, RETURNING SUNSHINE THOUGH STAYING COLD THROUGH THURSDAY
NIGHT.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 430 AM CST WED JAN 27 2021
EARLY MORNING SURFACE ANALYSIS SHOWS 1037 MB CANADIAN HIGH
PRESSURE OVER LAKE WINNIPEG AND RIDGING SOUTH INTO THE MIDWEST.
THIS WAS GIVING A CHILLY NE FLOW OVER IL. TEMPERATURES AT 4 AM
RANGED FROM 15 TO 20F ALONG AND NORTH OF A RUSHVILLE TO
BLOOMINGTON LINE (WITH WIND CHILLS OF 5-10F), TO THE LOWER 30S IN
SOUTHEAST IL. DEWPOINTS WERE ONLY IN THE LOW TO MID TEENS OVER THE
NORTHERN CWA, WHILE UPPER 20S IN SOUTHEAST IL. ALOFT A 541 DM 500
MB LOW WAS OVER CENTRAL KS WHILE A STRONGER 519 DM 500 MB LOW WAS
OFF THE WA/PACIFIC NORTHWEST COAST.
THE LATEST FORECAST MODEL SUITE TAKE THE CUTOFF LOW FROM CENTRAL
KS TO THE SOUTHERN IL/IN BORDER BY SUNSET TODAY AS IT WEAKENS TO
545 DM. WEAK FORCING AND ISENTROPIC LIFT WITH THIS WX SYSTEM OVER
SOUTHERN HALF OF IL TODAY. CAMS SHOW ALL SNOW WITH THIS WX SYSTEM
AS IT SPREADS LIGHT SHOW EASTWARD OVER CENTRAL/SOUTHERN IL DURING
MID TO LATE MORNING, THEN DIMINISHES IN EAST CENTRAL/SOUTHEAST IL
DURING LATE AFTERNOON AND EARLY THIS EVENING. MUCH DRIER AIR OVER
NORTHERN CWA, AND MAINLY EXPECT JUST FLURRIES THERE TODAY.
SOUTHERN/SW CWA ARE EXPECTED TO SEE 1-2 INCHES OF SNOW BY DUSK
WITH THE HIGHEST AMOUNTS ALONG AND SOUTH OF HIGHWAY 50 IN CLAY,
RICHLAND AND LAWRENCE COUNTIES. ABOUT A 6 HOUR PERIODS OF LIGHT
SNOW EXPECTED TODAY. HIGHS TODAY MOSTLY IN THE UPPER 20S AND LOWER
30S OVER CWA, BUT RANGE FROM THE MID 20S NW OF THE IL RIVER, TO
THE MID 30S BY LAWRENCEVILLE.
SOME LIGHT SNOW OR FLURRIES IN EASTERN IL/WABASH RIVER VALLEY
EARLY THIS EVENING, THEN CLOUDS EXPECTED TO DECREASE FROM THE NW
DURING TONIGHT. MUCH COLDER TEMPS ARRIVE OVERNIGHT WITH LOWS
2-7F NW OF THE IL RIVER (COLDEST IN KNOX AND STARK COUNTIES), TO
THE UPPER TEENS IN SOUTHEAST IL. NNW WINDS TO GIVE WIND CHILLS OF
ZERO TO 5 BELOW NORTHERN CWA AND AROUND 10F SOUTHEAST OF I-70.
LONG TERM
(THURSDAY THROUGH TUESDAY)
ISSUED AT 430 AM CST WED JAN 27 2021
STRONG 1037 MB CANADIAN HIGH PRESSURE OVER SOUTHERN MANITOBA TO
STRENGTHEN TO AROUND 1042 MB AS IT SETTLES INTO WESTERN ONTARIO BY
DAWN THU AND RIDGES SOUTHWARD INTO IL THU AFTERNOON. THIS WILL
BRING AMPLE SUNSHINE TO AREA THU AS NNW WINDS GRADUALLY DIMINISH
AS HIGH PRESSURE SETTLES IN. BELOW NORMAL HIGHS ON THU, IN THE MID
20S NORTHERN CWA AND LOWER 30S FROM I-72 SOUTH, WITH MID 30S FROM
HIGHWAY 50 SOUTH. TEMPS TO FALL QUICKLY THU EVENING WITH LOWS IN
THE LOW TO MID TEENS NORTHERN CWA AND UPPER TEENS TO NEAR 20F SW
CWA AND SOUTHEAST IL.
A STRONG UPPER LEVEL RIDGE SHIFTS EASTWARD INTO THE MS RIVER
VALLEY BY SUNSET FRIDAY. MEANWHILE STRONG SURFACE HIGH PRESSURE
SHIFTS EAST OF IL ON FRIDAY WITH RETURN SE FLOW STARTING TO MODIFY
TEMPS CLOSER TO NORMAL WITH PARTLY TO MOSTLY SUNNY SKIES, MORE
CLOUDS NORTHERN/NE CWA FRI AS MID/HIGH CLOUDS STREAM SE FROM THE
UPPER MS RIVER VALLEY. HIGHS FRI IN THE MID TO UPPER 30S, WITH SE
IL AND SPRINGFIELD SW NEAR 40F. MID AND HIGH CLOUDS INCREASE FROM
THE WEST DURING FRIDAY NIGHT AHEAD OF A STRONG STORM SYSTEM OFF
THE WEST COAST THAT EMERGES OVER THE SOUTHERN PLAINS BY DAWN SAT.
MODELS OVERALL HAVE TRENDED SLOWER AND FURTHER SOUTH WITH THIS
STRONG STORM SYSTEM, NOW APPEARING TO MOVE NEAR SOUTHERN IL
OVERNIGHT SAT NIGHT. GFS IS QUICKER SPREADING QPF EAST INTO IL
DURING SAT MORNING, WHILE ECMWF AND GEM MODELS WAIT UNTIL SAT
AFTERNOON TO BRING QPF INTO THE AREA. LEANING ON THE SLOWER ECMWF
AND GEM MODELS DUE TO DEEP UPPER LEVEL TROF/LOW DIGGING INTO THE
SOUTHERN PLAINS. SLOW MOVEMENT WOULD LIKELY LINGER PCPN THRU
SUNDAY OVER CWA. IF FURTHER SOUTH STORM TRACK VERIFIES, THIS
WOULD FAVOR BETTER CHANCE OF WINTRY PRECIPITATION AND POSSIBLE
SNOW ACCUMULATIONS OVER CENTRAL IL. FOR NOW HAVE RAIN SAT
AFTERNOON, MIXED WITH SNOW NORTHERN CWA, THEN MIXED PCPN SPREADING
SOUTHWARD INTO CENTRAL IL DURING SAT NIGHT INTO SUNDAY. SOUTHERN
IL MAINLY SEEING RAIN AND COULD BE ISOLATED THUNDERSTORMS IN
SOUTHERN IL SAT AFTERNOON INTO SAT NIGHT. QPF OF 1 INCH OR MORE
STILL LOOKS LIKELY WITH THIS STORM SYSTEM AS IT WILL HAVE DEEP
GULF MOISTURE ADVECTING NORTHWARD AHEAD OF IT INTO IL.
STRONG LOW PRESSURE TRACKS OFF THE MID ATLANTIC COAST BY MIDDAY
MONDAY, WHILE A LARGE UPPER LEVEL TROF/LOW WILL BE OVER THE OH/TN
RIVER VALLEYS. SOME MODELS STILL LINGER SOME LIGHT QPF IN EASTERN
IL ON MONDAY ON WESTERN FRINGE OF DEEP UPPER LEVEL TROF. ANY UPPER
LEVEL SHORT WAVES TRACKING SE FROM THE WESTERN GREAT LAKES COULD
KEEP CHANCE OF LIGHT SNOW/FLURRIES OVER EASTERN/NE IL ON MONDAY
ALONG WITH KEEPING LOW CLOUDS AROUND LONGER. CHILLY HIGHS MONDAY
IN THE LOW TO MID 30S.
UPPER LEVEL RIDGE SHIFTING EAST INTO THE MS RIVER VALLEY BY SUNSET
TUE ALONG WITH WEAK HIGH PRESSURE SETTLING INTO THE AREA, TO
RETURN DRY WEATHER AND RETURN OF SOME SUNSHINE TO THE AREA WITH
TEMPS STAYING ON THE CHILLY SIDE ON TUE. TEMPS TO LIKELY MODIFY
NEXT WED AS HIGH PRESSURE DRIFTS EAST OF IL, WHILE YET ANOTHER
LARGE STORM SYSTEM DIGS INTO THE ROCKIES AND MAY IMPACT THE
MIDWEST LATER NEXT WEEK.
AVIATION
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 600 AM CST WED JAN 27 2021
AN AREA OF LIGHT SNOW OVER MO AT DAWN WILL SPREAD EAST ACROSS
CENTRAL IL DURING MID/LATE MORNING AND MAINLY IMPACTING THE I-72
AIRPORTS ESPECIALLY SPI AND DEC FROM LATE MORNING INTO MID
AFTERNOON WITH VSBYS LOWERING TO 1-2 MILES. MAINLY FLURRIES WILL
OCCUR AT NORTHERN PIA AND BMI AIRPORTS THIS AFTERNOON. MVFR
CEILINGS ALREADY AT BMI, CMI AND DEC WILL SOON RETURN AT SPI,
WHILE PIA WILL BE ON NW EDGE OF MVFR CLOUDS TODAY. CEILINGS COULD
LOWER TO AROUND 1K FT WITH THE LIGHT SNOW AT SPI AND DEC THIS
AFTERNOON. VFR CONDITIONS RETURN DURING THIS EVENING WITH CLOUDS
SCATTERED OUT DURING THE NIGHT. NORTH TO NE WINDS 5-10 KTS EARLY
THIS MORNING TO INCREASE TO 8-13 KTS AND FEW HIGHER GUSTS TODAY
AND VEER MORE NORTHERLY. NNW TO NW WINDS OF 5-10 KTS EXPECTED
TONIGHT.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
SYNOPSIS...07
SHORT TERM...07
LONG TERM...07
AVIATION...07
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