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000
FXUS63 KILX 121156
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
656 AM CDT SUN MAY 12 2013

.DISCUSSION...
ISSUED 317 AM CDT SUN MAY 12 2013

SHORT TERM...TODAY THROUGH TUESDAY

CANADIAN HIGH PRESSURE BUILDING SOUTH THROUGH THE PLAINS WILL
CONTINUE TO SUPPLY COOL AIR TO THE CWA TODAY AND TONIGHT. HIGHS
IN THE UPPER 50S/NEAR 60 TODAY WILL BE COMPROMISE BETWEEN ONGOING
LOW AND MID LEVEL COLD ADVECTION AND STRONG MID MAY SUN. NORTHWEST
WINDS OCCASIONALLY GUSTING TO 20 MPH WILL ADD A CHILL TO THE AIR.
RIDGE AXIS SETTLES OVERHEAD TONIGHT AND MAY ALLOW FOR PATCHY FROST
FORMATION IN FAVORED COLD SPOTS DUE TO LIGHTER WINDS AND CLEAR
SKIES. FORECAST LOWS OF 36-39F MARGINAL FOR MORE WIDESPREAD FROST
SO WILL HOLD OFF ON ISSUING AN ADVISORY WITH THIS FORECAST
PACKAGE...BUT WILL HIGHLIGHT POTENTIAL OF PATCHY FROST IN HWO.

RETURN FLOW DEVELOPS MONDAY ON THE BACK SIDE OF THE DEPARTING HIGH
AND BEGINS A SIGNIFICANT WARMING TREND. ELEVATED WARM ADVECTION ON
THE LEADING EDGE OF THIS WARM AIR PUSH WILL LIKELY LEAD TO AN
INCREASE IN MID/HIGH LEVEL CLOUDS. ADEQUATE LIFT FOR SCATTERED
SHOWERS STILL APPEARS TO FOCUS FARTHER NORTH TOWARDS WI AND THE
LOWER GREAT LAKES MONDAY AFTERNOON AND NIGHT. ROBUST WARM
ADVECTION SETS UP OVER THE MIDWEST ON TUESDAY AS A RESULT OF A
SHORTWAVE TROF AND SFC LOW TRACKING THROUGH SOUTHERN MANITOBA.
DEEP LAYER W/SW FLOW SHIFTS A THERMAL RIDGE EAST FROM THE PLAINS.
RESULTING 850 MB TEMPS WARMING TO AROUND +20C WILL PRODUCE THE
WARMEST HIGHS THIS SPRING WITH WIDESPREAD MID 80S FOR THE WESTERN
AND CENTRAL CWA.

LONG TERM...WEDNESDAY THROUGH SATURDAY

A WARM AND UNSETTLED PATTERN LOOKS TO SET UP THROUGH THE EXTENDED
PORTION OF THE FORECAST. A COLD FRONT TRAILING OFF THE SOUTHERN
EDGE OF THE NORTHERN STREAM SHORTWAVE SHIFTS INTO THE AREA ON
WEDNESDAY BRINGING THE NEXT CHANCE FOR THUNDERSTORMS. GENERAL
AGREEMENT AMONG MEDIUM RANGE MODELS THAT THIS BOUNDARY WILL STALL
AND WAVER ACROSS THE MIDWEST UNDER ZONAL MID LEVEL FLOW THROUGH AT
LEAST THE END OF THE WEEK. WHILE THERE WILL LIKELY BE DRY
PERIODS...MODEL CONSENSUS OF LOW CHANCE POPS INTO SATURDAY APPEARS
REASONABLE. POPS WILL BE REFINED AS SHORTWAVES EVENTUALLY BECOME
BETTER RESOLVED. MID-LEVEL HEIGHTS AVERAGING AROUND 576 DM WITH
LITTLE AIRMASS CHANGE SUPPORTS TEMPS A FEW DEGREES ABOVE CLIMO
INTO NEXT WEEKEND.

25
&&

.AVIATION...
ISSUED 656 AM CDT SUN MAY 12 2013

GENERALLY QUIET/VFR CONDITIONS EXPECTED ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 12Z TAF VALID TIME. LITTLE/NO CLOUD
COVER IS ANTICIPATED EXCEPT FOR A FEW DIURNAL CU. WINDS WILL BE
PREDOMINANTLY OUT OF THE THE NORTHWEST...WITH GUSTS TO 20 KTS OR A
LITTLE HIGHER DURING PEAK DIURNAL MIXING.

BAK
&&

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

$$