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000
FXUS63 KILX 172344
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
644 PM CDT FRI MAY 17 2013

.DISCUSSION...
ISSUED 300 PM CDT FRI MAY 17 2013

AN EXTENDED PERIOD OF RAIN CHANCES WILL CONTINUE INTO THE WEEKEND
AND MOST OF NEXT WEEK. THE MAIN WEATHER FEATURES WILL BE A
STATIONARY FRONT AND UPPER LOW THE REST OF TODAY AND
SATURDAY...THEN A WARM FRONT ACROSS IL AND DEEPENING LOW PRESSURE
IN THE PLAINS ON SUNDAY AND MONDAY...THEN A SLOW MOVING OCCLUDED
LOW MONDAY NIGHT THROUGH TUESDAY NIGHT...BEFORE A COLD FRONT
FINALLY PUSHES ACROSS ILLINOIS ON WEDNESDAY.

THE BEST WINDOW OF OPPORTUNITY FOR ANY LONGER BREAKS IN THE RAIN
MAY BE SATURDAY AND SUNDAY...BUT STRONG INSTABILITY AS THE CAP
ERODES LATE SUNDAY AFTERNOON INTO SUNDAY EVENING MAY ALLOW FOR
STRONG TO SEVERE STORMS SUNDAY NIGHT NORTHWEST OF THE IL RIVER.

SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.

SHOWERS AND THUNDERSTORMS ERUPTED THIS AFTERNOON AS THE CAP
DISSIPATED...BUT COVERAGE WAS ISOLATED FOR THE MOST PART. THE
PRIMARY AREA OF ACTIVITY IN OUR AREA WAS FROM GALESBURG TO
HOOPESTON...CLOSER TO THE STATIONARY FRONT THAT EXTENDED ACROSS
NORTHERN IL. ADDITIONAL SHOWERS DEVELOPED FARTHER SOUTH FROM
JACKSONVILLE TO LAWRENCEVILLE ASSOCIATED WITH THE UPPER LOW MOVING
EAST INTO KENTUCKY. THE FRONT AND LOW WILL CONTINUE TO TRIGGER
SHOWERS AND STORMS INTO THE EVENING...BUT PROGRESSIVELY EAST WITH
TIME. BY MIDNIGHT...WE EXPECT PRECIP TO COME TO AN END IN CENTRAL
IL.

MOST OF THE DAY ON SATURDAY SHOULD BE DRY...BUT WE CAN NOT RULE
OUT SOME DIURNAL SHOWERS AND ISOLATED STORMS EAST OF I-57 AS THE
UPPER LOW LINGERS NEARBY TO THE EAST OF IL. A LULL IN THE RAIN
LOOKS LIKELY SATURDAY NIGHT AND MUCH OF SUNDAY...AS WARM AIR
SURGES INTO THE AREA. DEWPOINTS ON SUNDAY WILL CLIMB INTO THE
LOWER 70S AS HIGH TEMPS REACH THE UPPER 80S. A LOW LEVEL INVERSION
WILL PROVIDE A CAP UNTIL LATE IN THE DAY ON SUNDAY. ELEVATED
INSTABILITY WILL INCREASE DRAMATICALLY BY LATE AFTERNOON...WITH ML
CAPE VALUES AROUND 4K J/KG AND LI`S OF -10C. THE CAP WILL ERODE
FROM WEST TO EAST...REACHING PEORIA TO SPI BY 6-7 PM. SO OUR
WESTERN COUNTIES WILL HAVE THE BEST CHANCES FOR STRONG TO SEVERE
STORMS SUNDAY EVENING. TONED DOWN STORMS ARE EXPECTED TO ADVANCE
EAST TOWARD I-57 AFTER MIDNIGHT SUNDAY NIGHT.

MONDAY LOOKS TO BE LESS LIKELY FOR STORMS THAN PREVIOUS FORECAST
MODEL SOLUTIONS INDICATED. CLOUD COVER WILL KEEP HIGH TEMPS IN THE
LOWER 80S...BUT WE WILL REMAIN IN THE WARM SECTOR. WE REMOVED ANY
LIKELY POPS FROM MONDAY AND KEPT CHANCE POPS ACROSS THE AREA.
INSTABILITY PARAMS BECOME FAVORABLE AGAIN FOR STRONG STORMS MONDAY
EVENING...AS WE BREAK THE INVERSION AGAIN...BUT WE ARE NOT IN THE
SPC DAY 4 OUTLOOK FOR MON-MON NIGHT LIKE WE WERE IN THE DAY 5
OUTLOOK YESTERDAY. LACK OF A SOLID FOCUSING MECHANISM IS ONE OF
THE REASONS WHY. THE WARM FRONT WILL BE NORTH OF OUR AREA...AND
THE OCCLUDED LOW AND ITS ENERGY WILL BE MAINLY IN THE NORTHERN
PLAINS.

LONG TERM...TUESDAY THROUGH FRIDAY.

AS THE OCCLUDED LOW MOVES TOWARD IL ON TUESDAY...AND SETTLES OVER
N-NW IL TUESDAY NIGHT COVERAGE OF SHOWERS AND STORMS WILL BECOME
MORE WIDESPREAD. LIKELY POPS WERE INCLUDED EVERYWHERE BUT THE FAR
WESTERN COUNTIES TUESDAY AND TUESDAY NIGHT...WITH LOCALLY HEAVY
RAINFALL POSSIBLE AS STORM MOTIONS REMAIN SLOW.

THE COLD FRONT WILL EVENTUALLY MOVE ACROSS OUR AREA ON WEDNESDAY
AS THE LOW PRESSURE SYSTEM FINALLY PULLS AWAY TO THE NORTHEAST.
DRIER CONDITIONS WILL BEGIN TO RETURN WED NIGHT...BUT THE COLD
POOL ALOFT WILL KEEP CHANCES OF INSTABILITY SHOWERS IN PLACE FOR
THURSDAY.

THE COLDEST AIR OF THE WEEK WILL COME THURSDAY THROUGH FRIDAY...AS
HIGHS ONLY REACH THE LOW TO MID 70S...AND LOWS DIP INTO THE 50S.
SUNSHINE AND DRY CONDITIONS RETURN FOR FRIDAY...FINALLY.



&&

.AVIATION...
ISSUED 644 PM CDT FRI MAY 17 2013

SCATTERED SHOWERS WILL CONTINUE TO DEVELOP AND DRIFT NORTHWARD
OVER THE NEXT COUPLE OF HOURS...BEFORE DISSIPATING AFTER SUNSET.
WILL CARRY VCSH AT ALL TERMINALS BETWEEN 00Z AND 03Z ACCORDINGLY.
WITH LIGHT WINDS AND PLENTY OF LOW-LEVEL MOISTURE IN
PLACE...PARTIAL CLEARING OVERNIGHT WILL LEAD TO THE DEVELOPMENT OF
PATCHY FOG. BIG QUESTION WILL BE WHETHER OR NOT A LOW OVERCAST
WILL FORM AS WELL. NAM FORECAST SOUNDINGS ARE SUGGESTING CEILINGS
OF AROUND 1000FT OVERNIGHT INTO EARLY SATURDAY MORNING. THINK THIS
IS OVERDONE AND WILL ONLY INCLUDE SCT CLOUD COVER AROUND 1500FT
ALONG WITH 2-4SM FOG OVERNIGHT. ONCE THE MORNING FOG/CLOUDS
LIFT...NEGATIVE CU-RULE POINTS TO A PARTLY SUNNY DAY WITH CLOUD
BASES AROUND 5000FT. WINDS WILL INITIALLY BE SOUTHERLY EARLY THIS
EVENING...THEN WILL BACK TO E/SE LATER TONIGHT INTO SATURDAY

BARNES
&&

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

$$