000
FXUS63 KILX 162011
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
311 PM CDT THU MAY 16 2013

.DISCUSSION...
ISSUED 300 PM CDT THU MAY 16 2013

A STATIONARY FRONT WILL OSCILLATE NORTH AND SOUTH ACROSS ILLINOIS
OVER THE NEXT DAY AND A HALF...THEN THE FRONT SHOULD LIFT NORTH AS
A WARM FRONT FOR THE WEEKEND...PUSHING HIGHS INTO THE MID TO UPPER
80S BY SUNDAY. BANDS OF THUNDERSTORMS THAT DEVELOP THROUGH
TOMORROW WILL LIKELY BE SLOW MOVING, HEAVY RAIN PRODUCERS LIKE
TODAY`S STORMS. LOCALIZED AREAS COULD SEE SIGNIFICANT RAINFALL OF
2-3 INCHES IN A COUPLE HOURS WHILE NEARBY AREAS SEE LITTLE RAIN.
PINPOINTING THAT ACTIVITY WILL BE DIFFICULT...BUT DIURNAL TRENDS
SHOULD PUT MOST OF THE CONVECTION DURING THE AFTERNOON
TOMORROW...ESPECIALLY NEAR ANY OUTFLOW BOUNDARIES SET DOWN BY
TODAY`S STORMS.

A SLIGHT LULL IN STORMS SHOULD OCCUR THIS WEEKEND AS RIDGING IN
THE PLAINS BUILDS INTO IL. A STRONGER COLD FRONT IS EXPECTED TO
PUSH ACROSS IL ON MONDAY AND MONDAY NIGHT...BRINGING OUR BETTER
CHANCES OF THUNDERSTORMS. WE ARE IN THE SPC DAY 5 OUTLOOK FOR
STRONG TO SEVERE STORMS MON-MON NIGHT. A COOL DOWN IS PROJECTED
FOR TUES THROUGH THURSDAY BEHIND THE COLD FRONT...PULLING HIGHS
BACK INTO THE 70S...BUT STILL AT OR ABOVE NORMAL.

SHORT TERM...TONIGHT THROUGH SUNDAY.

SHOWERS AND STORMS WILL GENERALLY BE DIMINISHING AS WE HEAD INTO
THE EVENING. THE LINE OF CONVECTION MAINLY CENTERED ON A LINE
FROM RUSHVILLE TO TAYLORVILLE TO EFFINGHAM TO LAWRENCEVILLE...IS
EXPECTED TO LIFT NORTH THIS EVENING. THE RAP MODEL IS SHOWING THE
INSTABILITY AXIS FOLLOWING THE SAME PROGRESSION...WITH SOME SHOWER
ACTIVITY DEVELOPING DURING THAT TIME. IN THE LAST HOUR...PRECIP
COVERAGE AND UPDRAFT INTENSITY HAVE ALREADY BEGUN DIMINISHING OR
WEAKENING RESPECTIVELY. RADAR LOOPS SHOW VARIOUS OUTFLOW
BOUNDARIES MOVING NORTH ACROSS OUR COUNTIES...AND MAY END UP BEING
A FOCUS FOR EVENING SHOWERS ALONG AND NORTH OF I-72.
STILL...COVERAGE WILL BE ISOLATED IN GENERAL.

FRIDAY MORNING...THE LOCATION OF THE BEST INSTABILITY WILL BE
ALONG AND NORTH OF I-74...SO ANY MORNING CONVECTION ON FRIDAY MAY
BE FOCUSED IN THAT AREA. DURING THE AFTERNOON...AN UPPER LOW
PRESSURE WAVE IS FORECAST TO LIFT NORTHEAST ACROSS IL...IN CONCERT
WITH INCREASING MOISTURE AND INSTABILITY AS THE STATIONARY FRONT
OSCILLATES NORTHWARD WITH THE WAVE. COVERAGE OF STORMS SHOULD BE
MORE THAN TODAY...BASED ON THE SUPPORT OF THE UPPER WAVE AND JET
DYNAMICS. ANY SUNSHINE THAT HEATS UP THE BOUNDARY LAYER WILL HELP
TO CREATE A FEW STRONG UPDRAFTS WITH SMALL HAIL, GUSTY WINDS, AND
VERY HEAVY RAINFALL.

THE STORMS MAY LINGER INTO THE EVENING EAST OF I-57...BUT SHOULD
DIMINISH BY MIDNIGHT. BY 12Z SAT MORNING...THE UPPER LOW IS
FORECAST TO BE CENTERED IN SOUTHERN INDIANA...WHICH WILL HELP PUT
PRECIP CHANCES MAINLY IN OUR SOUTHEAST COUNTIES ALONG AND SOUTHEAST
OF A LINE FROM SHELBYVILLE TO PARIS. THE SLOW DEPARTURE OF THE LOW
WILL KEEP CHANCES OF SHOWERS AND STORMS THROUGH SATURDAY AFTERNOON
IN THE SOUTHEAST.

THE WARM FRONT DEPARTING INTO NORTHERN IL FOLLOWED BY RIDGING AT
THE SURFACE AND ALOFT SATURDAY NIGHT AND SUNDAY SHOULD HELP MAKE
MOST AREAS DRY FOR THE LAST HALF OF THE WEEKEND. THE ADDITIONAL
SUNSHINE ON SUNDAY ALONG WITH DEEPER WARM AIR WILL HELP PUSH HIGH
TEMPS INTO THE MID TO UPPER 80S...WITH MUGGY DEWPOINTS IN THE
UPPER 60S TO NEAR 70. HEAT INDEX READINGS SUNDAY AFTERNOON WILL
CLIMB INTO THE 90S.

LONG TERM...MONDAY THROUGH THURSDAY.

ON MONDAY...AN OCCLUDING LOW PRESSURE PRESSURE SYSTEM IN THE
EASTERN DAKOTAS WILL CREATE SOME WARM FRONTOGENESIS TO THE
SOUTHEAST OF THE LOW ACROSS OUR NORTHERN COUNTIES. THAT WILL
CREATE A FOCUS FOR CONVECTION BY MONDAY AFTERNOON. MONDAY
NIGHT...A COLD FRONT WILL MOVE ACROSS IL PRODUCING STRONG TO
SEVERE STORMS AS ML-CAPE VALUES CLIMB TO NEAR 2K J/KG. BULK SHEAR
IS EXPECTED TO REACH OVER 40KT AS WELL...SO EMBEDDED SUPERCELLS
WILL BE POSSIBLE IN THE LINE OF STORMS THAT MOVES THROUGH.

STORMS ARE EXPECTED TO LINGER INTO TUESDAY AS THE UPPER COLD POOL
SLOWLY MAKES PROGRESS INTO ILLINOIS. WE KEPT LIKELY POPS SOUTHEAST
OF I-72...AND CHANCE ELSEWHERE. TUESDAY NIGHT PRECIP COVERAGE
SHOULD DIMINISH...WITH CHANCE POPS STILL IN PLACE ACROSS THE
BOARD. AN ELONGATED SURFACE TROUGH IS PROJECTED TO LINGER ACROSS
NORTHERN ILLINOIS INTO WED AS THE OCCLUDED UPPER LOW BECOMES MORE
OF AN OPEN WAVE AND SEND A SURFACE LOW EASTWARD ACROSS WISCONSIN.
THAT PROGRESSION WILL KEEP SCATTERED SHOWERS POSSIBLE AS FAR
SOUTH AS CENTRAL ILLINOIS THROUGH THURSDAY...ESPECIALLY EAST OF
I-55. PRECIP AMOUNTS MID WEEK SHOULD REMAIN LIGHT...BUT STILL
CLOUDS AND COOLER AIR WILL KEEP HIGH TEMPS BACK IN THE
70S...CLOSER TO NORMAL.

SHIMON
&&

.AVIATION...
ISSUED 1225 PM CDT THU MAY 16 2013

POP-UP NATURE OF SHOWERS/STORMS THIS AFTERNOON WILL BE A CHALLENGE
IN GOING WITH ANYTHING MORE THAN VCTS. ONE LINE OF STORMS WAS
LOCATED JUST SOUTH OF KSPI/KTAZ BUT REMAINING STATIONARY...SO WILL
NOT ADD A PREVAILING TSRA AT KSPI YET. MANY OF THE STORMS SHOULD
FADE WITH SUNSET...AND HAVE GONE WITH LARGELY DRY CONDITIONS AT
ALL TAF SITES MUCH OF THE NIGHT. LATEST HIGH- RESOLUTION GUIDANCE
SUGGESTING SOME LATE NIGHT DEVELOPMENT NEAR KPIA/KBMI...AND HAVE
PUT SOME VCTS BACK THERE...ALTHOUGH MAIN CONCERN LATE NIGHT WILL
BE WITH AREAS OF MVFR FOG. ON FRIDAY MORNING...POTENTIAL EXISTS
FOR ADDITIONAL SHOWERS/STORMS TO LIFT UP FROM THE SOUTH...AND HAVE
MENTIONED VCTS AT KSPI/KDEC AFTER 15Z.

GEELHART
&&

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

$$