Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 200446
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1146 PM CDT SUN APR 19 2015

.UPDATE...
ISSUED AT 904 PM CDT SUN APR 19 2015

LOW PRESSURE OVER NORTHEAST IL CONTINUES TO LIFT NORTHEAST WHILE A
COLD FRONT APPROACHES FROM THE WEST...CURRENTLY ALIGNED FROM
AROUND GALESBURG TO PITTSFIELD. FRONT WILL CROSS CENTRAL IL
FORECAST ZONES THROUGH EARLY MORNING PROVIDING A FOCUS FOR SHOWERS
AND A THUNDERSTORM OR TWO. CURRENT TRENDS ARE FOR A FAIRLY
PRONOUNCED BREAK IN INTENSITY IN THE FRONTAL ZONE SHOWERS ACROSS
CENTRAL IL AS ONE SHORTWAVE PASSES TO THE SOUTH AND ANOTHER TO THE
NORTH. NEVERTHELESS...AT LEAST SCATTERED SHOWERS RE-DEVELOPING
LOOKS LIKELY GIVEN THE MOIST CONDITIONS ACROSS THE AREA. MAINLY
LIGHT AMOUNTS EXPECTED. UPDATES SENT TO TRIM EVENING POPS FROM
SOUTHWESTERN FORECAST AREA...AS WELL AS THUNDERSTORM COVERAGE.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 253 PM CDT SUN APR 19 2015

SFC LOW EVIDENT ON BOTH RADAR AND SATELLITE THIS AFTERNOON. LOW WILL
CONTINUE TO LIFT NORTH AND EVENTUALLY MORE NORTHEAST THIS
EVENING. RATHER EXPANSIVE AREA OF PRECIP WITH SOME AREAS GETTING A
FEW BREAKS AS DRY AIR WORKS INTO THE SYSTEM...ALTHOUGH SCATTERED
SHOWERS ALSO FILLING IN. MODELS CONTINUE TO HINT AT A SECONDARY
WAVE WITH THE H5 TROF PASSING LATER THIS EVENING/TONIGHT...AND
RIGHT NOW, THAT SAME TROF HAS MORE LIGHTNING ASSOCIATED WITH IT
AND ITS ASSOCIATED FRONT. BETTER DYNAMICS BACK TO THE WEST AND NOT
WILLING TO DROP POPS TOO MUCH IN THE OVERNIGHT HOURS. MAINTAINING
THUNDER AT LEAST BEFORE 05Z. SECONDARY CONCERN WRAPPED UP IN RISK
FOR FOG. BOUNDARY LAYER IS WET ENOUGH TO SUSTAIN A VIS ISSUE
SHOULD ANY PARTICULAR AREA SEE A LITTLE BIT OF A BREAK...BUT NOT
ENOUGH TO WARRANT A LARGER SCALE MENTION AT THIS POINT.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 253 PM CDT SUN APR 19 2015

SCATTERED SHOWERS MAY LINGER FOR A FEW HOURS MONDAY MORNING,
BEFORE THE SURFACE LOW DEPARTS FAR ENOUGH TO THE NORTHEAST AND
FORCING FOR PRECIP WANES. BY AFTERNOON, ALL BUT THE FAR EASTERN
COUNTIES SHOULD BE DRY. HOWEVER, MUCH COLDER AIR WILL BE ARRIVING.
CLOUDS MAY BE TOUGH TO CLEAR DUE TO THE UPPER TROUGH REMAINING
FIRMLY IN PLACE ACROSS THE UPPER MIDWEST. THE CLOUDS AND COLDER AIR
WILL LIMIT HIGH TEMPS ON MONDAY TO THE UPPER 50S TO LOW 60S. ON TOP
OF THAT, GUSTY NORTHWEST WINDS AT 20-30 MPH WILL ADD MORE CHILL TO
THE AIR. THE STRONG NW WINDS WILL CONTINUE ON TUESDAY, AS THE
PRESSURE GRADIENT REMAINS TIGHT. HIGHS MAY REACH THE LOWER 60S IN
MOST AREAS ON TUESDAY, BUT BLUSTERY CONDITIONS WILL MAKE IT FEEL
COOLER.

A LOBE OF ENERGY ROTATING AROUND THE BACK SIDE OF THE TROUGH WILL
PUSH A COLD FRONT ACROSS IL ON TUESDAY NIGHT INTO WED MORNING. THOSE
FEATURES COULD TRIGGER SHOWERS ACROSS OUR SOUTHERN COUNTIES, MAINLY
SOUTH OF I-72. MOISTURE WILL BE LIMITED, SO ANY SHOWERS SHOULD BE
BRIEF WITH RAINFALL AMOUNTS LESS THAN A TENTH OF AN INCH.

HIGH PRESSURE BUILDING INTO IL FROM THE NORTHERN PLAINS WILL PROVIDE
A PERIOD OF DRY AND COOL CONDITIONS FROM WED AFTERNOON THROUGH
FRIDAY. HIGHS WILL LIKELY REMAIN IN THE UPPER 50S, WITH A FEW
SOUTHERN SPOTS FINALLY CLIMBING ABOVE 60 AGAIN ON FRIDAY. FROST
POTENTIAL WILL BE PRESENT MAINLY NORTH OF I-74 WED NIGHT AND THUR
NIGHT, WHEN LIGHT WINDS AND CLEAR SKIES CREATE FAVORABLE RADIATIONAL
COOLING CONDITIONS. LOWS COULD DROP TO AROUND 35, WHICH IS ENOUGH
FOR FROST TO FORM AT GROUND LEVEL. FROST ADVISORIES MAY BE NEEDED IN
PORTIONS OF THE AREA BOTH OF THOSE NIGHTS.

THERE IS AGREEMENT BETWEEN THE ECMWF AND GFS ON A SYSTEM ARRIVING IN
THE SOUTHERN STREAM FRIDAY NIGHT, INCREASING RAIN CHANCES SOUTH OF I-
74. ELEVATED INSTABILITY WITH THE SYSTEM MAY BE ENOUGH FOR THE FEW
STORMS TO DEVELOP SOUTH OF I-72, BUT NO STRONG STORMS ARE EXPECTED.
THE CANADIAN KEEPS THE AFFECTS OF THAT SYSTEM SOUTH OF OUR FORECAST
AREA. WE WENT WITH CONSENSUS AND KEPT CHANCE POPS ACROSS OUR
SOUTHERN COUNTIES FRIDAY NIGHT AND SATURDAY. DRY CONDITIONS SHOULD
RETURN FOR SUNDAY. HOWEVER, THE COOLER CONDITIONS WILL CONTINUE
THROUGH SUNDAY, WHEN HIGHS STILL ONLY REACH THE LOW 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1146 PM CDT SUN APR 19 2015

COLD FRONT FROM AROUND KGBG-KIJX THIS EVENING WILL CROSS CENTRAL
IL TERMINALS THROUGH 10Z CAUSING A FEW SHOWERS AND BRINGING AN
INCREASE IN WESTERLY WINDS. A MIX OF IFR/LIFR CEILINGS AND MAINLY
MVFR VSBYS IN BR WILL GRADUALLY IMPROVE AFTER FRONTAL
PASSAGE...WITH GENERALLY VFR CONDITIONS BY AROUND 14Z. WINDS
INCREASING TO W 15-20 KTS WITH GUSTS UP TO 30 KTS LATE MORNING
THROUGH AFTERNOON. WINDS AND GUSTS DECREASING AFTER 00Z TUESDAY.

&&

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

$$

UPDATE...ONTON
SHORT TERM...HJS
LONG TERM...SHIMON
AVIATION...ONTON


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