Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 010136
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
836 PM CDT SUN MAY 31 2015

.UPDATE...
ISSUED AT 830 PM CDT SUN MAY 31 2015

AN UPPER LEVEL TROF TO OUR SOUTH WAS BRINGING SOME MOISTURE NORTH
INTO PARTS OF EXTREME SOUTHERN ILLINOIS EARLY THIS EVENING WHILE A
COOL BUT DRY AREA OF HIGH PRESSURE WAS ANCHORED TO OUR NORTH. OUR
AREA WAS STUCK IN BETWEEN THESE TWO SYSTEMS WITH A BROAD
NORTHEASTERLY FLOW KEEPING THE EXTENSIVE CLOUD COVER OVER MOST OF
THE FORECAST AREA. THE LATEST SURFACE ANALYSIS INDICATES A FRONTAL
BOUNDARY WELL TO OUR SOUTH WITH SEVERAL WAVES OF LOW PRESSURE
NOTED ALONG THE BOUNDARY WHERE SURFACE DEW POINTS WERE WELL INTO
THE 60S...WHILE FURTHER NORTH INTO OUR AREA...DEW POINTS HAVE
DROPPED INTO THE UPPER 40S TO LOWER 50S. OVER THE LAST HOUR...WE
HAVE SEEN SOME REPORTS OF DRIZZLE AND VERY LIGHT RAIN BEING
REPORTED OVER SOUTHEAST IL AS SOME DEEPER MOISTURE SHIFTS NORTH
INTO THE REGION FROM THE UPPER LEVEL LOW OVER NORTHERN ARKANSAS
THIS EVENING. AS A RESULT...HAVE ADDED THE MENTION OF SOME
SPRINKLES OVER EAST CENTRAL THRU SOUTHEAST ILLINOIS FOR THE REST
OF TONIGHT.

ELSEWHERE...CLOUD COVER WAS TRYING TO THIN OUT SOME ACROSS OUR
NORTH OVER THE PAST COUPLE OF HOURS WITH THE LATEST RAPID
REFRESH MODEL SUGGESTING A FEW LOCATIONS TO OUR NORTH MAY ACTUALLY
SCATTER OUT LATE TONIGHT/MONDAY MORNING. THAT REMAINS TO BE SEEN
AT THIS POINT BASED ON OUR LOW LEVEL FLOW SO WILL WE WILL CONTINUE
WITH THE CLOUDY SKY FOR THE REST OF TONIGHT. WE SHOULD HAVE THE
UPDATE OUT BY 900 PM.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 312 PM CDT SUN MAY 31 2015

19Z/2PM SURFACE ANALYSIS SHOWS AN UNSEASONABLY STRONG 1033MB HIGH
CENTERED OVER ONTARIO...WITH RIDGING EXTENDING SOUTHWESTWARD INTO
THE CENTRAL/SOUTHERN PLAINS.  COOL NORTHEASTERLY FLOW AROUND THE
HIGH HAS KEPT TEMPERATURES MAINLY IN THE 50S ACROSS CENTRAL ILLINOIS
THIS AFTERNOON.  MEANWHILE FURTHER SOUTH AND EAST...A SLOW-MOVING
FRONTAL BOUNDARY EXTENDS FROM OHIO TO EAST TEXAS.  A WAVE OF LOW
PRESSURE CURRENTLY OVER SOUTHERN ARKANSAS WILL TRACK ALONG THE FRONT
TONIGHT...REACHING CENTRAL TENNESSEE BY 12Z MON.  SHOWERS ASSOCIATED
WITH THIS FEATURE WILL SPREAD NORTHWARD...WITH THE GFS BRINGING THEM
AS FAR NORTHWEST AS THE I-70 CORRIDOR.  DUE TO THE DRY NORTHEASTERLY
FLOW IN PLACE ACROSS THE REGION...THINK THIS IS A BIT TOO
AGGRESSIVE...SO WILL FOLLOW THE NAM/RAPID REFRESH SOLUTION WHICH
KEEPS SHOWERS FURTHER SOUTH ACROSS THE OHIO RIVER VALLEY LATE
TONIGHT.  DESPITE THE DRY FORECAST...OVERCAST CONDITIONS WILL
PREVAIL ACROSS THE ENTIRE AREA THROUGHOUT THE NIGHT AS LOW-LEVEL
MOISTURE REMAINS TRAPPED BENEATH A SUBSIDENCE INVERSION CENTERED AT
AROUND 900MB.  MAY SEE SOME PARTIAL CLEARING ACROSS THE FAR N/NW
KILX CWA AROUND LACON AND GALESBURG TOWARD DAWN...HOWEVER PROSPECTS
FOR WIDESPREAD CLEARING REMAIN BLEAK.

.LONG TERM...(MONDAY THROUGH SUNDAY)
ISSUED AT 312 PM CDT SUN MAY 31 2015

DRY WEATHER WITH LOW CLOUDS STILL LINGERING OVER MUCH OF CENTRAL AND
SOUTHEAST IL MONDAY AS A LOW AMPLITUDE HIGH PRESSURE RIDGE BUILDS
SLOWLY INTO THE PLAINS AND MIDWEST WHILE A BROAD TROUGH REMAINS OVER
THE SOUTHEAST. ALTHOUGH GENERAL WEAK SUBSIDENCE AT MID AND UPPER
LEVELS WILL TAKE PLACE OVER ILLINOIS...CLOUDS WILL BE SLOW TO
CLEAR AS LOW LEVEL NORTHEASTERLY FLOW CONTINUES TO ADVECT
MOISTURE ACROSS THE AREA AND MODEL SOUNDINGS CONTINUE TO ADVERTISE
SUBSTANTIAL MOISTURE LINGERING BELOW 850 MB BELOW AN INVERSION.
CLEARING PROSPECTS WILL BE BEST FROM AROUND PEORIA NORTHWESTWARD.
BELOW NORMAL TEMPERATURES WILL CONTINUE WITH HIGHS IN THE UPPER
60S.

DRY WEATHER WITH A WARMING TREND WILL CONTINUE THROUGH MIDWEEK AS
THE PLAINS/MIDWEST RIDGE DOMINATES THE WEATHER ACROSS THE AREA.
HIGHS FROM THE MID 70S TUESDAY TO LOW 80S THURSDAY. BY FRIDAY...A
CHANCE OF THUNDERSTORMS WILL RETURN AS MODELS DEVELOP CONVECTIVE
ACTIVITY OVER THE PLANS AND SPREAD IT EASTWARD INTO ILLINOIS. BOTH
GFS AND ECMWF ADVERTISING A BREAK IN PRECIPITATION SATURDAY NIGHT SO
HAVE ONLY INCLUDED LOW POPS BELOW MENTIONABLE THRESHOLDS...THEN A
CHANCE RETURNING SUNDAY AS A STRONGER LOW OVER CANADA AND TRAILING
COLD FRONT APPROACH AS ADVERTISED BY GFS AND A WEAKER BUT SIMILAR
SOLUTION BY THE ECMWF.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 600 PM CDT SUN MAY 31 2015

LITTLE CHANGE IN THE FORECAST THRU THIS PERIOD AS A PERSISTENT
NORTHEASTERLY FLOW KEEPS THE MVFR CIGS IN PLACE. WE MAY SEE THE
USUAL LOWERING OF THE CIGS OVERNIGHT THAT MAY PUSH A FEW OF OUR
TAF SITES TO IFR FOR A TIME BUT NOT EXPECTING THAT TO LAST LONG
ENOUGH TO INCLUDE IN THIS FORECAST. LOOK FOR CIGS TO RANGE FROM
1200 TO 2500 FEET THRU MOST OF MONDAY WITH A NORTHEAST WIND
HOLDING IN AT 10 TO 15 KTS.


&&

.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...SMITH
SHORT TERM...BARNES
LONG TERM...ONTON
AVIATION...SMITH


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