Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 232052
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
ISSUED BY NATIONAL WEATHER SERVICE CHICAGO IL
352 PM CDT MON MAR 23 2015

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 346 PM CDT MON MAR 23 2015

PRECIPITATION ASSOCIATED WITH TODAY`S SHORTWAVE HAS EXITED TO
THE EAST. LOW LEVEL CLOUD COVER REMAINS IN ITS WAKE. STRONG
HIGH PRESSURE REMAINS IN PLACE ACROSS THE EASTERN GREAT LAKES
WHICH TENDS TO SUGGEST THAT THE CLOUDS WILL LINGER MUCH OF THE
NIGHT IN SPITE OF SOME POTENTIAL CLEARING TO THE SOUTH. WITH THE
HIGH IN PLACE TONIGHT...LOW LEVEL DRY ENE FLOW WILL KEEP A COOL
LOW LEVEL AIR MASS IN PLACE.

ATTENTION SHIFTS TO THE UPPER TROUGH ENTERING THE SOUTHERN ROCKIES.
THERE WILL BE SOME LEAD SHORTWAVE ENERGY PUSHING EAST THROUGH
THE CENTRAL PLAINS AND MID MISSOURI VALLEY TONIGHT. STRONG LOW LEVEL
WARM ADVECTION/ISENTROPIC LIFT INTO THE LOW-MID LEVEL FRONTAL ZONE
WILL RESULT IN SHOWERS TO MOVE INTO ILLINOIS LATE TONIGHT INTO
TOMORROW MORNING. THERE IS SOME WEAK INSTABILITY ABOVE 700-600 MB
AS THESE SHOWERS ROLL IN WHICH MAY RESULT IN A FEW EMBEDDED
THUNDERSTORMS...ESPECIALLY SOUTH OF I-72. MEANWHILE NORTH OF
I-74 AND CLOSER TO I-72...SURFACE TEMPERATURES LOOK TO DIP BELOW
FREEZING TONIGHT INTO EARLY TUESDAY MORNING. THEREFORE RAIN/FREEZING
RAIN CONCERNS COME INTO PLAY. CONFIDENCE IS NOT SUPER HIGH ON ICE
ACCUMULATIONS GIVEN THE WARMER GROUND CONDITIONS...BUT IT IS
CERTAINLY CONCERN EAST OF I-55 WHERE PRECIPITATION HAS A BETTER
CHANCE OF COMING IN DURING THE COOL HOURS OF THE NIGHT AND EARLY
MORNING. BY MID-LATE MORNING THE LOWER LEVEL WARMING WILL ALLOW
SURFACE TEMPS TO BE ABOVE FREEZING AREA-WIDE.

THERE MAY BE A LULL IN THE SHOWER ACTIVITY IN AFTERNOON AS THE
MID LEVEL BAROCLINIC ZONE SHIFTS NORTH AND THE LEAD WAVES MOVES
EASTWARD. THE SURFACE WARM FRONT WILL EVENTUALLY MOVE NORTH THROUGH
THE CWA DURING THE AFTERNOON AND MORE SO THE EVENING HOURS.

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 327 AM CDT MON MAR 23 2015

THE CENTER OF LOW PRESSURE LIFTING OUT OF THE SOUTHERN PLAINS
WILL CROSS THE LOCAL AREA TUESDAY NIGHT AND QUICKLY PUSH WELL TO
THE NORTHEAST BY NOON WEDNESDAY. UNCERTAINTY IN THE EXACT TRACK OF
THE LOW WILL CREATE CHALLENGES FOR LOW TEMPERATURE FORECASTS AND
THE NORTHERN EXTENT OF THUNDERSTORM ACTIVITY...WITH THE BEST
CHANCE OF THUNDER BEING IN THE TUESDAY EVENING HOURS AS THE LOW
CENTER AND UPPER TROUGH AXIS MOVE OVERHEAD.

AFTER A BRIEF DRY PERIOD WEDNESDAY...AND AT LEAST PART OF
WEDNESDAY AFTERNOON...ANOTHER WEAKER DISTURBANCE WEDNESDAY
NIGHT FOLLOWS QUICKLY ON THE HEELS OF THE TUESDAY NIGHT SYSTEM.
THIS TOO SHOULD QUICKLY CLEAR TO THE EAST AFTER DAYBREAK THURSDAY.

WITH THE PASSAGE OF THE FRONTAL ZONE ASSOCIATED WITH THE SECOND
SYSTEM...COOLER AIR SETTLES INTO THE AREA UNDER A BROAD DOME OF
HIGH PRESSURE FOR THE REMAINDER OF THE WEEK AND EARLY WEEKEND. BY
LATE SUNDAY THE DOMINANT AREA OF COOL HIGH PRESSURE SLIDES INTO THE
SOUTHEAST CONUS ALLOWING MILDER AND MORE HUMID RETURN FLOW TO BEGIN
WORKING BACK INTO THE MIDWEST.  WITH THE RETURN OF HIGHS IN THE 50S
OR WARMER COMES INCREASED CHANCES OF PRECIPITATION FOR LATE IN THE
WEEKEND...BUT AT THIS RANGE AM ONLY CONFIDENT ENOUGH ON TIMING AND
EXTENT TO INCLUDE CHANCE POPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 103 PM CDT MON MAR 23 2015

PRECIP TYPE CONCERNS HAVE ENDED FOR THE NEAR TERM ACROSS THE
TERMINALS AS THE PRECIP SHIELD IS NOW EAST ALONG THE ILLINOIS AND
INDIANA BORDER. MVFR CONDITIONS WILL CONTINUE TO SPREAD SOUTHEAST
ACROSS THE AREA THIS AFTERNOON AND EVENING. STILL SOME UNCERTAINTY
AS TO HOW LONG THESE CIGS WILL LAST AND HOW FAR EAST THEY
SPREAD...WITH SOME EROSION BEING NOTED IN THE FAR SOUTHWEST AND
SPREADING EASTWARD. EXPECT AREAS OF MVFR OVERNIGHT...THEN CONCERNS
SWITCH TO PRECIPITATION TUESDAY MORNING. THUNDER PARAMETERS APPEAR
TOO MARGINAL TO MENTION IN THIS SET OF TAFS. ALSO...THERE MAY BE A
RAIN/SNOW MIX IN THE MORNING...ESPECIALLY EAST TOWARDS KBMI/KPIA.
OTHERWISE EXPECT A BATCH OF RAIN SHOWERS IN THE MORNING.


&&

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

$$

SHORT TERM...KMD
LONG TERM...LENNING
AVIATION...KMD



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