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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
657 AM CDT MON MAY 4 2015

.SHORT TERM...(TODAY)
ISSUED AT 342 AM CDT MON MAY 4 2015

OUTFLOW BOUNDARY FROM CONVECTION THAT DEVELOPED AHEAD OF A FRONTAL 
BOUNDARY EXTENDING THROUGH THE GREAT LAKES AND INTO THE CENTRAL 
PLAINS HAS MOVED INTO PORTIONS OF THE CENTRAL IL FORECAST 
AREA...EXTENDING FROM NEAR PEORIA TO PONTIAC. BOUNDARY CONTINUES TO 
TRIGGER SCATTERED THUNDERSTORMS BEHIND IT...WHILE AHEAD LIGHT 
SHOWERS ARE WIDELY SCATTERED ACROSS CENTRAL IL. MID-LEVEL 
INSTABILITY ACROSS THE REGION WILL CAUSE SHOWERS AND THUNDERSTORMS 
TO CONTINUE TO DEVELOP ACROSS MUCH OF CENTRAL IL MAINLY FROM I-70 
NORTHWARD THROUGH MORNING. A POSSIBLE LULL IN PRECIPITATION 
INDICATED BY MODEL FORECASTS LATE MORNING AS CURRENT AREA OF 
CONVECTION SHIFTS NORTHEASTWARD AND RE-DEVELOPMENT OF CONVECTION 
TAKES PLACE ALONG THE APPROACHING FRONTAL BOUNDARY FOR THE 
AFTERNOON. SPC CONTINUES TO ADVERTISE A MARGINAL RISK FOR SEVERE 
STORMS CONTAINING HAIL/STRONG WIND GUSTS THIS AFTERNOON/EVENING 
THROUGH MUCH OF CENTRAL AND NORTHERN IL NEAR THE FRONTAL BOUNDARY 
WHERE AT LEAST SOME OVERLAP OF MODERATE BULK SHEAR MAY COMBINE WITH 
1000-2000 J CAPE. HIGH TEMPERATURES QUITE WARM AGAIN TODAY...UPPER 
70S TO LOW 80S...WITH BREEZY SW WINDS 10-15 MPH.

.LONG TERM...(TONIGHT THROUGH SUNDAY)
ISSUED AT 342 AM CDT MON MAY 4 2015

SOME CONVECTION SETTLING INTO THE MIDWEST THIS MORNING ALONG AND 
AHEAD OF THE BOUNDARY JUST TO THE NORTHWEST. SAME BOUNDARY PROVIDING 
THE FOCUS FOR SHOWERS TODAY WILL KEEP THE THREAT FOR SOME SHOWERS 
AND THUNDERSTORMS THROUGH THE OVERNIGHT IN THE NORTHERN HALF OF THE 
STATE.  EXACT LOCATION OF THE STALLED BOUNDARY VARIES A BIT FROM 
MODEL TO MODEL.  SMALL WAVES MOVING ALONG THE BOUNDARY WILL KEEP 
PRECIP CHANCES IN THE NORTHERN TIER OF THE STATE THROUGH TUESDAY.  
HIGH PRESSURE SLOWLY BUILDING IN WITH SOME SOUTHERLY WINDS PUSHING 
THE FRONT BACK TO THE NORTH AND OUT OF THE FORECAST AREA FOR TUESDAY 
NIGHT THROUGH WED NIGHT. PRECIP CHANCES SLOWLY EDGING BACK INTO 
CENTRAL ILLINOIS AS AN UPPER LEVEL WAVE PUSHES OUT OF THE SW.  THE 
ENERGY IS PART OF A GENERAL PATTERN SHIFT TO MORE SOUTHWESTERLY FLOW 
WITH THE UPPER LEVEL TROF DIGGING BACK IN OVER THE SWRN CONUS.  THE 
SFC LOW WITH THAT STORM MOVES OUT INTO THE UPPER MIDWEST AND INTO 
CANADA BY THE END OF THE WEEK, BUT IN SHIFTING TO MORE SOUTHWESTERLY 
FLOW ALOFT, OPENS THE DOOR TO A SERIES OF SHORTWAVES THAT KEEP THE 
FORECAST WET FOR THE END OF THE WORK WEEK AND INTO THE WEEKEND.  
TEMPS RATHER WARM THROUGH THE FORECAST WITH OVERCAST AND RAINY SKIES 
KEEPING THE OVERNIGHT LOWS UP A BIT, BUT LIKELY NOT NEARLY AS WARM 
AS THE TREND IN THE GUIDANCE.  HAVE KNOCKED THEM DOWN A COUPLE 
DEGREES. SOUTHERLY FLOW AND A RELATIVELY WARM AIRMASS KEEPING THE 
HIGHS A BIT ABOVE NORMS.  HOWEVER, WITH THE LIFTING OF THE DEEP TROF 
OVER THE SW INTO THE GREAT LAKES, THE WARMER AIRMASS IS SHUNTED OFF 
TO THE EAST AND COOLER AIR MOVES INTO THE MIDWEST AT LEAST BRIEFLY 
AT THE END OF THE FORECAST PD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 0657 AM CDT MON MAY 4 2015

SCATTERED SHRA/TSRA FROM KSPI-KDEC-KCMI NORTHWARD WITH ISOLD-SCT
SHRA TO THE SOUTH AS A COLD FRONTAL BOUNDARY APPROACHES FROM THE
NORTHWEST. GENERALLY VFR CONDITIONS WITH CIGS BKN050-070 BUT ISOLD
IFR/MVFR VSBYS AND MVFR CIGS IN HEAVIER TSRA AND BR. EXPECT THIS
ACTIVITY TO SHIFT SOUTHWARD THROUGH THE DAY AND EVENING BEFORE
BEGINNING TO SHIFT BACK NORTHWARD AFTER 06Z. POTENTIAL IMPROVEMENT
IN CONDITIONS BRIEFLY FROM AROUND 15-18Z HOWEVER
TIMING/OCCURRENCE TOO UNCERTAIN FOR MENTION IN 12Z TAFS. WINDS
GENERALLY SSW 8-12 KTS UNTIL 00Z...SHIFTING TO SE04-08 KTS.
BRIEFELY GUSTY AND VARIABLE IN VICINITY OF THUNDERSTORMS.

&&

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

$$

SHORT TERM...ONTON
LONG TERM...HJS
AVIATION...ONTON

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