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000
FXUS63 KILX 142002
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
302 PM CDT FRI JUN 14 2013

.DISCUSSION...
ISSUED 302 PM CDT FRI JUN 14 2013

MAIN CONCERN DURING THIS FORECAST PACKAGE REMAINS THE
CHANCES OF PCPN FOR TONIGHT THROUGH MONDAY. MODELS REMAIN IN GOOD
AGREEMENT WITH OVERALL UPPER LEVEL PATTERN NEXT 3-5 DAYS BUT THEN
BEGIN TO DIFFER SOME IN THE EXTENDED PERIODS FOR NEXT WEEK. ON THE
SFC HOWEVER...THINGS ARE A LITTLE DIFFERENT. EXTENDED MODELS LOOK
OK THROUGH ABOUT 48HRS BUT THEN BEGIN TO LOOK MESSY/UNSURE OF
THEMSELVES AS TO WHAT THE PRESSURE FIELDS ARE GOING TO LOOK LIKE
BEYOND SUNDAY. SO A BLEND OF MODELS FOR THE FORECAST LOOKS OK
THROUGH ABOUT 48HRS AND THEN AGAIN FOR NEXT WEEK. IN BETWEEN THOSE
TIMES...WILL JUST GO WITH PERSISTENCE AND HOPE THE MODELS WILL
WORK OUT DIFFERENCES ONCE THOSE TIME FRAMES GET CLOSER.

SHORT TERM...TONIGHT THROUGH MONDAY

MODELS SEEM TO INDICATE A SERIES OF THUNDERSTORMS COMPLEXES
POSSIBLE THE NEXT TWO NIGHTS...POSSIBLY THREE. CURRENT CONVECTION
NORTHWEST OF THE AREA WILL CONTINUE TO DIMINISH AS IT MOVES
SOUTHEAST AWAY FROM THE BEST SUPPORT AND MOISTURE. HOWEVER...AS
THE LOW LEVEL JET BECOMES MORE FOCUSED BACK OUT IN THE PLAINS
TONIGHT AN MCS IS EXPECTED TO DEVELOP NORTHWEST OF THE AREA AND
THEN MOVE EAST-SOUTHEAST TOWARD THE CWA OVERNIGHT. WILL HAVE
LINGERING PCPN CHANCES IN THE WEST THIS EVENING...BUT THEN SHIFT
THE FOCUS TO THE NORTHWEST FOR THE REMAINDER OF THE NIGHT...WITH
HIGHEST POPS AFTER 06Z-09Z IN THE NORTHWEST AND WEST. OUTFLOW
BOUNDARIES FROM THIS COMPLEX OF STORMS WILL BECOME THE FOCUS FOR
MORE THUNDERSTORMS TOMORROW LATE MORNING INTO TOMORROW AFTERNOON
AND PROBABLY CONTINUING INTO TOMORROW NIGHT. SO POPS WILL BECOME
LIKELY ACROSS THE WHOLE AREA TOMORROW AFTERNOON THROUGH TOMORROW
NIGHT.

ANOTHER MCS IS POSSIBLE TO THE WEST OF THE AREA...MOVING EAST INTO
THE AREA TOMORROW NIGHT INTO SUNDAY MORNING. POPS WILL REMAIN
LIKELY THROUGH SUNDAY IN THE CENTRAL AND SOUTH BUT THERE WILL
LIKELY BE SOME PERIODS WHERE THERE WILL BE BREAKS BETWEEN THE PCPN
ENDING AND THEN STARTING AGAIN. IN THESE SITUATIONS...TIMING OF
THESE BREAKS DEPENDS ON THE MICRO-SCALE FEATURES...WHICH SYNOPTIC
MODELS HAVE DIFFICULTY PICKING UP PAST 24HRS. SO WILL WAIT TIL
TOMORROW AND LATE TO FINE TUNE OTHER PERIODS BEYOND TOMORROW.

THOUGH MODELS SHOW A BREAK IN THE PCPN FOR SUNDAY NIGHT...STILL
SOME UNCERTAINTY. SO WILL PUSH POPS DOWN INTO THE CHC CATEGORY FOR
NOW AND WAIT TIL LATE TO SEE WHAT THE REAL STORY COULD BE. PCPN
SHOULD CONTINUE INTO MONDAY...BUT AGAIN...MODELS DIFFER ON WHO
THIS WILL LOOK SO WILL JUST KEEP CHC POPS THERE TOO.

HIGH TEMPS WILL WARM SLIGHTLY BUT STILL REMAIN AT OR JUST ABOVE
NORMAL...IN THE LOWER TO MIDDLE 80S.

LONG TERM...MONDAY NIGHT THROUGH FRIDAY

LINGER PCPN IS POSSIBLE IN EASTERN AND SOUTHEASTERN IL MONDAY
EVENING BUT DRY WEATHER IS EXPECTED AFTER THAT. ANOTHER HIGH PRSS
AREA BUILDS IN AFTER THIS ROUND OF PCPN DO DRY WEATHER IS EXPECTED
TUESDAY THROUGH WEDNESDAY NIGHT. REMAINDER OF THE WEEK SHOULD BE
DRY TOO...BUT BOTH ECMWF AND GFS ARE TRYING TO BRING MORE PCPN
INTO THE REGION FOR LAST PART OF THE WEEK. SOME UNCERTAINTY HERE
AS BOTH MODELS BUILD A RIDGE OVER THE REGION...THEY JUST DIFFER ON
HOW STEEP THE RIDGE WILL BE. THE ECMWF HAS A STEEPER RIDGE...WHICH WILL
PREVENT PCPN...WHILE THE GFS IS SOMEWHAT FLATTER...WHICH WOULD ALLOW
SOME PCPN TO MOVE INTO THE REGION. SO FOR NOW...WILL JUST HAVE
SILENT 20PCT IN THE WESTERN HALF FOR THUR THROUGH FRI.

TEMPS WILL BE AROUND NORMAL TO START THE WEEK BUT SHOULD WARM TO
THE MIDDLE 80S BY THE END OF THE WEEK. TEMPS COULD END UP BEING
WARMER...AS EVIDENCE OF 850 TEMPS OF AROUND 20C BEING FORECAST BY
THE MODELS.

AUTEN
&&

.AVIATION...
ISSUED 1240 PM CDT FRI JUN 14 2013

VFR CONDITIONS EXPECTED OUTSIDE OF THUNDERSTORMS NEXT 24 HRS.
FIRST IN A SERIES OF TSTM COMPLEXES TO AFFECT THE MIDWEST OVER THE
NEXT COUPLE DAYS...IS SHIFTING EAST ALONG THE IA/MO BORDER. WITH
SFC RIDGE AXIS AND DRIER AIR STILL OVER CENTRAL IL FEEL MUCH OF
THIS WILL DISSIPATE AS IT PUSHES EAST OF THE MS RIVER THIS
AFTERNOON...LEAVING A VEIL OF HIGH CLOUDS OVER THE TERMINALS INTO
THIS EVENING. MOST MODEL GUIDANCE SUPPORTS ANOTHER COMPLEX
DEVELOPING OVER IA TONIGHT AND SHIFTS E/SE INTO NORTHERN AND
CENTRAL IA SATURDAY MORNING...IN A WEAKENING MODE AS LOW LEVEL JET
SUPPORT WEAKENS AFTER 12Z. THUS HAVE MOST CONFIDENCE IN THIS
ACTIVITY AFFECTING PIA...WHILE FARTHER SITES TO THE SOUTHEAST JUST
HAVE VCTS THROUGH THE REMAINDER OF THE MORNING. LIGHT/VRB WINDS
UNDER THE RIDGE AXIS THIS AFTERNOON WILL GRADUALLY COME AROUND TO
THE SOUTHEAST THIS EVENING BUT REMAIN LIGHT UNDER 10 KTS
OVERNIGHT. HIGHER SPEEDS OF 10+ KTS ARE EXPECTED AFTER 12Z SAT
AS GRADIENT DEVELOPS AHEAD OF A LOW PRESSURE WAVE SHIFTING ACROSS
IA.

25
&&

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

$$