675 
FXUS63 KILX 260456
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1156 PM CDT TUE SEP 25 2012

.DISCUSSION...
ISSUED 854 PM CDT TUE SEP 25 2012

A TRAINING BAND OF SHOWERS AND THUNDERSTORMS CONTINUES TO TRACK
ALONG A FRONTAL BOUNDARY EXTENDING FROM THE CENTRAL PLAINS ACROSS
SOUTHERN ILLINOIS. THE BULK OF THE MORE INTENSE STORMS HAVE STAYED
SOUTH OF THE FORECAST AREA....ALTHOUGH CLAY...RICHLAND...AND
LAWRENCE COUNTIES HAVE BEEN BRUSHED BY A FEW OF THE STORMS. DO NOT
EXPECT SIGNIFICANT MOVEMENT OF THIS AREA OF PRECIPITATION THROUGH
THE NIGHT WITH MINIMAL NORTHWARD/SOUTHWARD PUSH FROM UPPER LEVEL
DISTURBANCES RIDING OVER THE SURFACE BOUNDARY. HOWEVER...CLOUD
TOPS HAVE CONTINUED TO COOL AND SOME EXPANSION IN THE WIDTH OF THE
CONVECTIVE LINE IS LIKELY AS THE NOCTURNAL LOW LEVEL JET INCREASES
A BIT. 

GOING FORECAST SEEMS TO HAVE A PRETTY GOOD HANDLE ON CURRENT
CONDITIONS. ONLY PLAN ON MINOR TWEAKS AT THIS TIME FOR THE LATEST
TRENDS. 

BAK
&&

.AVIATION...
ISSUED 1155 PM CDT TUE SEP 25 2012

A NEARLY STATIONARY FRONTAL BOUNDARY WAS SOUTH OF THE CENTRAL
ILLINOIS TERMINALS THIS EVENING. ALTHOUGH THE PRECIPITATION
ASSOCIATED WITH THE BOUNDARY HAS STAYED SOUTH OF THE
AREA...ASSOCIATED CLOUDS HAVE SPREAD IN SPECIALLY AT
KSPI...KDEC...KCMI. AN UPPER LEVEL WAVE RIDING ALONG THE BOUNDARY
MAY SPREAD SOME PRECIPITATION INTO KSPI...KDEC...AND KCMI FOR MUCH
OF WEDNESDAY. HOWEVER...HAVE ONLY INCLUDED A VCSH MENTION AT THIS
TIME AS DRY NORTHEAST FLOW TO THE NORTH OF THE BOUNDARY SHOULD
RETARD THE NORTHWARD EXTENT OF THE PRECIPITATION TO SOME DEGREE.
EXPECT WINDS TO BE FAIRLY LIGHT/VARIABLE WITH THE FRONTAL ZONE IN
THE VICINITY...ALTHOUGH KPIA AND KBMI WILL BE FAR ENOUGH NORTH TO
DEVELOP MORE OF A NORTHEASTERLY FLOW AS HIGH PRESSURE STARTS TO
PUSH SOUTH ON WEDNESDAY.

BAK
&&

.PREV DISCUSSION...

ISSUED 255 PM CDT TUE SEP 25 2012

UNSETTLED WEATHER EXPECTED TO CONTINUE THE NEXT FEW DAYS WITH A FEW
ROUNDS OF SHOWERS AND THUNDERSTORMS THIS WORK WEEK ESPECIALLY OVER
SOUTHERN AREAS. 12Z SHORT RANGE MODELS ARE IN FAIR AGREEMENT
DURING MIDWEEK THRU THU AND HAVE TRENDED FURTHER SOUTH WITH
FRONTAL BOUNDARY AND QPF FIELDS BY THU. EXTENDED MODELS CONTINUE
TO LOOK DRIER AND COOLER THIS WEEKEND INTO EARLY NEXT WEEK THOUGH
MODELS DIFFER WITH POSITIONS OF UPPER LEVEL LOW/TROF IN THE
EASTERN STATES. MET AND MAV TEMPS SIMILAR THROUGH THU NIGHT AND
STAYED CLOSE TO WITH WARMEST READINGS IN SE IL ESPECIALLY WED.

SHORT TERM...TODAY THROUGH FRIDAY NIGHT

SPC CONTINUES TO HAVE AREAS SOUTH OF I-70 IN A SLIGHT RISK OF SEVERE
STORMS LATE THIS AFTERNOON AND INTO THIS EVENING. LARGE MCS HAD
ROLLED INTO THE CENTRAL APPALACHIANS OF EASTERN KY THAT BROUGHT
RAINS TO CENTRAL AND SOUTHERN IL THIS MORNING WITH AS MUCH AS
1.5-2.5 INCHES OF RAIN SW OF SPRINGFIELD. RADAR MOSAIC SHOWS WIDE 
BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS SOUTH OF I-72 AND
EXTENDING AS FAR SOUTH AS A ST LOUIS TO ROBINSON LINE. INSTABILITY
HAS INCREASED DURING THE AFTERNOON ESPECIALLY SW COUNTIES WITH
CAPES UP TO 1500-2000 J/KG AT MID AFTERNOON. SURFACE MAP SHOWS
COLD FRONT OVER CENTRAL LOWER MI INTO SOUTHERN WI AND CENTRAL IA/NE
WHILE A 1008 MB LOW WAS NEAR KC WITH A WARM FRONT NORTH OF I-70 IN
MO/IL. DEWPOINTS CLIMB INTO THE MID TO UPPER 60S IN THE WARM
SECTOR WITH TEMPS RISING INTO THE UPPER 70S AND LOWER 80S OVER SW
IL.

USED THE HRRR...RUC MODELS INTO THIS EVENING AND THEN THE NAM AND
SREF MODELS THEREAFTER FOR HANDLING QPF FIELDS NEXT COUPLE OF DAYS.
INCREASE TO CATEGORICAL POPS SOUTH OF I-72 TONIGHT AND ALSO
INCREASED QPF AMOUNTS ESPECIALLY FROM CHARLESTON/MATTOON SOUTH
WHERE HALF TO 1 INCH LIKELY WITH LOCALLY UP TO 2 INCH AMOUNTS.
SLIGHT CHANCE OF SEVERE STORMS LATE THIS AFTERNOON INTO MID
EVENING SOUTH OF I-70 WHERE BULK SHEAR OF 30-40 KTS COMBINED WITH
CAPES PEAKING FROM 2000-2500 J/KG TO GIVE RISK OF A FEW SEVERE
STORMS. CONTINUED LIKELY CHANCES OF CONVECTION IN SE IL WED WHILE
LOWERED POPS TO 20% OR LESS IN NORTHERN AREAS. COLD FRONT OVER
SOUTHERN WI TO SAG SOUTHWARD INTO CENTRAL IL NEAR I-72 BY 18Z/WED
AND SLIP SOUTH THROUGH SE IL WED AFTERNOON AND NEAR THE OHIO RIVER
BY 06Z/THU. BEST CHANCES OF CONVECTION WILL SHIFT SOUTHWARD DURING
THIS TIME. SPC HAS 5% RISK OF SEVERE STORMS FROM HIGHWAY 50 SOUTH
ON WED AFTERNOON. CHANCE OF CONVECTION MAINLY CONFINED TO SE IL THU
AND FRI AS 1026 MB HIGH PRESSURE OVER THE GREAT LAKES REGIONS
KEEPS THE FRONTAL BOUNDARY SOUTH OF IL. A FEW SHORT WAVES EJECTING
EASTWARD FROM THE MO VALLEY ACROSS THE OHIO VALLEY WILL BRING
CHANCES OF CONVECTION INTO MAINLY SE IL THU/FRI. 

LONG TERM...SATURDAY THROUGH TUESDAY

DRY AND COOLER WEATHER GENERALLY EXPECTED THIS WEEKEND INTO EARLY
NEXT WEEK WITH UPPER LEVEL TROF/LOW OVER THE GREAT LAKES REGION
AND NEAR IL. FRONTAL BOUNDARY AND DEEPER MOISTURE TO SHIFT FURTHER
SOUTH OF THE OHIO RIVER THIS WEEKEND WHILE ANY SHOWERS FROM THE
UPPER LEVEL LOW/TROF MAINLY NE OF IL. MODELS ALSO SHOWING
DEVELOPING OF AN UPPER LEVEL LOW EARLY NEXT WEEK IN THE LOWER MS
VALLEY KEEPING ITS MORE ACTIVE WEATHER SOUTH OF IL. TEMPS A BIT ABOVE
NORMAL DURING MID WEEK ESPECIALLY THE LOWS COOL BACK THIS WEEKEND
INTO EARLY NEXT WEEK BUT STILL CLOSE TO NORMAL AND NOT NEARLY AS COOL
AS EARLIER THIS PAST WEEK. 

KH
&&

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

$$