Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 040153
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
853 PM CDT FRI JUL 3 2015

.UPDATE...
ISSUED AT 845 PM CDT FRI JUL 3 2015

WEAK UPPER LEVEL WAVE THAT PRODUCED THE LIGHT SHOWERS OVER EAST
CENTRAL ILLINOIS THIS AFTERNOON AND THE WIDELY SCATTERED
THUNDERSTORMS...WITH LOCALLY HEAVY RAINFALL OVER SOUTHEAST
ILLINOIS...HAS SHIFTED JUST OFF TO OUR SOUTHEAST THIS EVENING.
IN ITS PLACE...HIGH PRESSURE WILL SHIFT SLOWLY ACROSS THE STATE
OVERNIGHT AND SATURDAY BRINGING QUIET WEATHER TO CENTRAL THRU
SOUTHEAST ILLINOIS. THE COMBINATION OF LIGHT WINDS...CLEAR SKY AND
ABUNDANT LOW LEVEL MOISTURE WILL LEAD TO SOME PATCHY FOG LATE
TONIGHT INTO EARLY SATURDAY...ESPECIALLY OVER EAST CENTRAL AND
SOUTHEAST ILLINOIS. FORECAST SOUNDINGS SHOWING ANY FOG THAT DOES
FORM WILL BE QUITE SHALLOW AND QUICK TO BURN OFF JUST AFTER
SUNRISE SATURDAY MORNING. AFTER THAT...A WARM DAY SHAPING UP FOR
SATURDAY WITH AFTERNOON TEMPERATURES A BIT CLOSER TO WHERE THEY
SHOULD BE FOR EARLY JULY. THE CURRENT FORECAST HAS A GOOD HANDLE
ON THE EVENING AND OVERNIGHT TRENDS...AS A RESULT...NO ZFP UPDATE
WILL BE NEEDED.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 247 PM CDT FRI JUL 3 2015

UPPER LEVEL TROF (576-578 DM AT 500 MB) OVER NORTHERN INDIANA AND
CENTRAL IL WAS INTERACTING WITH DAYTIME HEATING AND MODEST DEWPOINTS
IN THE MID 60S GENERATING ISOLATED SHOWERS IN EAST CENTRAL IL EAST
OF I-55. HEAVIER RAINS WITH SCATTERED SHOWERS AND THUNDERSTORMS WERE
ALONG AND SOUTH OF HIGHWAY 50 IN SOUTHEAST IL AND MORE NUMEROUS IN
KY AND FAR SOUTHERN IL CLOSER TO A FRONTAL BOUNDARY TIED TO A WEAK
1010 MB SURFACE LOW PRESSURE IN NORTH CENTRAL KY.  ISOLATED
CONVECTION SHOULD DIMINISH FROM NW TO SE DURING THE EVENING AND
MOSTLY BE DRY AFTER DARK (02Z/9 PM).

WEAK HIGH PRESSURE 1016 MB OVER CENTRAL NEBRASKA/IA/LOWER MI TO
DRIFT SE INTO CENTRAL IL OVERNIGHT INTO SATURDAY HELPING DECREASING
CLOUDS WITH NE WINDS 5-10 MPH THIS AFTERNOON BECOME LIGHT AND
VARIABLE TONIGHT. HRRR SHOWS SOME FOG APPEARING IN EAST CENTRAL AND
SE IL OVERNIGHT WHERE HIGHER DEWPOINTS CURRENTLY IN MID TO UPPER 60S
AND AGREE FOG WILL FORM ESPECIALLY WITH LIGHT WINDS AND DECREASING
CLOUD COVER. LOWS OVERNIGHT RANGE FROM 58-64F WITH MILDEST READINGS
IN SOUTHEAST IL WHERE HIGHER DEWPOINTS.

.LONG TERM...(SATURDAY THROUGH FRIDAY)
ISSUED AT 247 PM CDT FRI JUL 3 2015

HOLIDAY WEEKEND LOOKS TO BE IN GOOD SHAPE FOR OUR AREA...AS HIGH
PRESSURE DRIFTS EASTWARD THROUGH THE MIDWEST. HAVE REMOVED ANY
LINGERING POP`S IN THE FAR SOUTHERN REACHES OF THE FORECAST AREA FOR
SATURDAY. WARMER CONDITIONS RETURN THROUGH THE WEEKEND...AND RAISED
TEMPERATURES ON SUNDAY BY A FEW DEGREES INTO THE 86-88 DEGREE RANGE
AS 925 MB TEMPERATURES RISE TO AROUND 22C.

MAIN FOCUS REMAINS WITH PRECIPITATION TRENDS FOR NEXT WEEK. LATEST
MODEL GUIDANCE HAS BEEN SLOWING DOWN THE COLD FRONT EARLY NEXT WEEK
A BIT...WHICH WOULD FAVOR DRY CONDITIONS CONTINUING OVER THE EASTERN
THIRD OF THE FORECAST AREA THROUGH MONDAY AFTERNOON. BULK OF THE
RAIN WILL OCCUR MONDAY NIGHT AND TUESDAY MORNING. PRECIPITABLE WATER
VALUES STILL PROGGED TO BE AROUND 2.1 INCHES AHEAD OF THE FRONT WITH
AN ATTENDANT THREAT OF HEAVY RAIN...BUT MOST OF THE GUIDANCE
SUGGESTS A MORE PROGRESSIVE FRONT WHICH SHOULD HOPEFULLY REDUCE THE
EXCESSIVE RAIN POTENTIAL IN ANY GIVEN AREA. THE MODELS ARE FAIRLY
DIVERGENT FOR THE SECOND HALF OF THE UPCOMING WEEK...WITH THE
DISPARITIES FOCUSED ON THE POTENTIAL FOR THE FRONT TO RETURN
NORTHWARD AS LOW PRESSURE RIDES ALONG THE BOUNDARY. THE GFS IS MOST
GUNG-HO ON THIS SOLUTION AND HAS THE BOUNDARY ALL THE WAY INTO
NORTHERN ILLINOIS BY THURSDAY EVENING...WHILE THE ECMWF KEEPS THE
WAVE ACROSS THE OHIO VALLEY AND OUR AREA MOSTLY CONTROLLED BY HIGH
PRESSURE. HAVE KEPT POPS IN THE 25-35% RANGE OVER MOST OF THE AREA
FOR NOW...BUT CONFIDENCE IS NOT ESPECIALLY HIGH AT THE MOMENT.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 545 PM CDT FRI JUL 3 2015

MAIN FORECAST CONCERN THIS PERIOD WILL BE WITH THE POTENTIAL FOR
SOME MVFR VSBYS IN FOG LATE TONIGHT...OTHERWISE...WE ARE EXPECTING
VFR CONDITIONS FOR THE REMAINDER OF THE FORECAST PERIOD. WEAK HIGH
PRESSURE WILL DRIFT ACROSS THE AREA TONIGHT INTO SATURDAY MORNING
BRINGING LIGHT WINDS AND A CLEAR SKY TO THE TAF SITES. WITH
ABUNDANT LOW LEVEL MOISTURE IN PLACE COMBINED WITH A CLEAR SKY AND
LIGHT WIND...CONDITIONS ARE FAVORABLE FOR SOME SHALLOW FOG TO FORM
IN THE 09Z-12Z TIME FRAME. WHAT FOG DOES DEVELOP WILL QUICKLY
DISSIPATE AS TEMPERATURES WARM THRU THE MORNING HOURS WITH SOME
SCATTERED CUMULUS DEVELOPING BY LATE MORNING INTO THE AFTERNOON
HOURS. BASES SHOULD RANGE FROM 3500-4500 FEET DURING THE AFTERNOON
BEFORE DISSIPATING BEFORE 00Z. WINDS WILL ONCE AGAIN BE A NON-
FACTOR DURING THIS FORECAST PERIOD WITH MOST OF THE FORECAST
INDICATING A LIGHT AND VARIABLE WIND OVER ALL THE TAF SITES.


&&

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

$$

UPDATE...SMITH
SHORT TERM...07
LONG TERM...GEELHART
AVIATION...SMITH


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