814  
FXUS63 KILX 010756  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
256 AM CDT SAT NOV 1 2014  
   
SHORT TERM
 
(TODAY)  
ISSUED AT 256 AM CDT SAT NOV 1 2014  
 
07Z/2AM WATER VAPOR IMAGERY SHOWS POTENT UPPER LOW DIVING SOUTHWARD  
INTO THE SOUTHERN APPALACHIANS, WHILE DEEP-LAYER NORTHERLY FLOW  
PREVAILS ACROSS THE GREAT LAKES/MIDWEST. WHILE MUCH OF THE  
PRECIPITATION ASSOCIATED WITH THIS FEATURE HAS NOW PASSED WELL EAST  
AND SOUTH OF ILLINOIS, PLENTY OF LAKE-ENHANCED CLOUD COVER CONTINUES  
TO STREAM SOUTHWARD FROM LAKE MICHIGAN. LATEST IR SATELLITE IMAGERY  
SHOWS PARTLY TO MOSTLY CLOUDY SKIES ALONG/EAST OF A BLOOMINGTON TO  
SHELBYVILLE LINE WITH CLEAR SKIES FURTHER WEST ACROSS THE REMAINDER  
OF THE KILX CWA. MOST MODEL GUIDANCE SUGGESTS CLOUDS WILL RAPIDLY  
DISSIPATE BY MID-MORNING: HOWEVER, THINK THIS IS TOO FAST GIVEN  
CURRENT SYNOPTIC SET-UP. CONTINUED N/NE FLOW WITHIN THE  
SURFACE-925MB LAYER WILL LIKELY LEAD TO A PERSISTENT LAKE-ENHANCED  
CLOUD BAND FROM THE CHICAGO AREA SOUTHWARD INTO THE FAR EASTERN CWA  
THROUGH MIDDAY. CLOUDS WILL EVENTUALLY SCATTER DURING THE AFTERNOON  
AS SUBSIDENCE INCREASES UPON APPROACH OF SURFACE RIDGE AXIS. END  
RESULT WILL BE PARTLY SUNNY SKIES ALONG/EAST OF I-57 AND MOSTLY  
SUNNY CONDITIONS FURTHER WEST. WILL BE ANOTHER UNSEASONABLY COOL  
DAY AS WELL, WITH AFTERNOON HIGHS ONCE AGAIN REMAINING IN THE 40S.  
WINDS WILL BE LIGHTER THAN YESTERDAY, BUT MAY STILL GUST TO BETWEEN  
20 AND 25MPH AT TIMES ACROSS THE EAST BEFORE PRESSURE GRADIENT EASES  
LATER IN THE DAY.  
 

 
   
LONG TERM
 
(TONIGHT THROUGH FRIDAY)  
ISSUED AT 256 AM CDT SAT NOV 1 2014  
 
HIGH PRESSURE WILL SLIDE EASTWARD ACROSS CENTRAL ILLINOIS TONIGHT,  
RESULTING IN CLEAR AND COLD CONDITIONS. MODEL CONSENSUS PLACES  
SURFACE RIDGE AXIS FROM SOUTHERN LAKE MICHIGAN TO THE LOWER OHIO  
RIVER VALLEY BY 12Z SUN, SO LIGHTEST WINDS AND MAXIMUM RADIATIONAL  
COOLING WILL BE FOCUSED ACROSS THE E/SE CWA. FURTHER WEST, LIGHT  
S/SE RETURN FLOW ON THE BACK SIDE OF THE HIGH OVERNIGHT WILL LEAD  
TO SLIGHTLY WARMER TEMPS. LOW TEMPERATURES WILL RANGE FROM THE  
LOWER 20S NEAR THE INDIANA BORDER TO AROUND 30 DEGREES IN THE  
ILLINOIS RIVER VALLEY.  
 
ONCE HIGH TRACKS FURTHER EASTWARD, WARM ADVECTION WILL BEGIN IN  
EARNEST ON SUNDAY. BOTH THE NAM AND GFS INDICATE A BAND OF  
MID-LEVEL MOISTURE LIFTING THROUGH THE AREA, PRODUCING PARTLY SUNNY  
SKIES. DESPITE CLOUD COVER, INCREASING SOUTHERLY WINDS AND RAPIDLY  
RISING UPPER HEIGHTS WILL HELP TEMPS RECOVER INTO THE UPPER 40S AND  
LOWER 50S. AS PRESSURE GRADIENT TIGHTENS, SOUTHERLY WINDS WILL GUST  
TO AROUND 25MPH ON MONDAY, HELPING BRING EVEN WARMER AIR INTO THE  
REGION. THIS WILL LEAD TO THE WARMEST DAY OF THE FORECAST PERIOD  
WITH HIGHS TOPPING OUT IN THE LOWER TO MIDDLE 60S.  
 
HIGHLY AMPLIFIED UPPER PATTERN WILL BEGIN TO BREAK DOWN EARLY NEXT  
WEEK, AS A VIGOROUS WAVE CURRENTLY OVER CALIFORNIA FLATTENS CENTRAL  
CONUS RIDGE. ONE PIECE OF ENERGY FROM THIS WAVE WILL TRACK  
NORTHEASTWARD INTO THE GREAT LAKES BY TUESDAY, WHILE A SECOND PIECE  
WILL CUT-OFF FROM THE MAIN FLOW ACROSS THE DESERT SOUTHWEST. THE  
GREAT LAKES WAVE WILL FLATTEN THE PREVAILING RIDGE AND DRIVE A COLD  
FRONT INTO ILLINOIS MONDAY NIGHT INTO TUESDAY. 00Z NOV 1 MODELS  
HAVE TRENDED SLOWER WITH THE PATTERN BREAK DOWN AND THE ARRIVAL OF  
THE FRONT, SO HAVE PULLED POPS ACROSS THE WEST MONDAY AFTERNOON.  
HAVE ALSO DELAYED RAIN CHANCES MONDAY NIGHT, WITH AREAS EAST OF I-55  
REMAINING DRY UNTIL AFTER MIDNIGHT. ATMOSPHERE WILL INITIALLY BE  
QUITE DRY, SO RAIN WILL BE SLOW TO DEVELOP. FORECAST SOUNDINGS  
GRADUALLY MOISTEN FROM THE TOP-DOWN AND SATURATE SUFFICIENTLY FOR  
PRECIP OVERNIGHT EVERYWHERE EXCEPT THE FAR E/SE. BEST RAIN  
CHANCES WILL TAKE PLACE ON TUESDAY AS FRONT SLOWLY PUSHES THROUGH  
THE AREA. WILL CARRY LIKELY POPS ACROSS THE BOARD, WITH RAINFALL  
AMOUNTS BETWEEN 0.25 AND 0.50.  
 
STILL SOME DISAGREEMENT CONCERNING SPEED OF FROPA, WITH THE ECMWF  
BEING FASTER THAN THE GFS. GIVEN AMPLIFIED PATTERN INITIALLY, WILL  
TREND TOWARD THE SLOWER GFS, WHICH RESULTS IN CONTINUED SHOWER  
CHANCES ALONG/SOUTH OF I-70 INTO WEDNESDAY. ONCE FRONT PUSHES  
FURTHER SOUTHEAST, COOL/DRY WEATHER WILL BE ON TAP THROUGH FRIDAY.  
AFTER THAT, MODEL AGREEMENT REMAINS POOR AS ECMWF TAKES DESERT  
SOUTHWEST CUT-OFF LOW AND PUSHES IT NORTHEASTWARD INTO THE MIDWEST  
ON SATURDAY, WHILE THE GFS KEEPS IT MUCH FURTHER SOUTH ALONG THE  
GULF COAST. GIVEN DISCREPANCIES, WILL ONLY MENTION LOW CHANCE POPS  
FRIDAY NIGHT INTO SATURDAY.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1110 PM CDT FRI OCT 31 2014  
 
VFR CONDITIONS ARE EXPECTED ACROSS MOST OF THE AREA THIS FORECAST  
PERIOD. WILL NEED TO KEEP AN EYE ON KCMI AS FORECAST SOUNDINGS  
INDICATE THEY WILL BE ON THE EDGE OF SOME LOW VFR CIGS WITH SOME  
TEMPO MVFR CIGS STREAMING SOUTH OFF OF LAKE MICHIGAN THRU SUNRISE  
SATURDAY. 250 METER WINDS OFF LOCAL VAD WIND PROFILERS CONTINUES  
TO SHOW A NORTH TO NORTHEAST FLOW OFF OF LAKE MICHIGAN SO THE  
BANDS OF CLOUDS TRACKING S-SW WILL OCCASIONALLY GET INTO PARTS  
OF OUR AREA, MAINLY ALONG AND EAST OF THE I-55 CORRIDOR. ONCE  
THE LARGE AREA OF HIGH PRESSURE TO OUR NORTHWEST SETTLES CLOSER  
TO OUR AREA, BOUNDARY LAYER WINDS WILL SHIFT ENOUGH TO SHUNT THE  
LAKE MOISTURE MORE INTO INDIANA SATURDAY MORNING. NORTHERLY  
SURFACE WINDS HAVE BEEN SLOWLY DECREASING THIS EVENING AND EXPECT  
THAT TREND TO CONTINUE OVERNIGHT. WITH THE AREA OF HIGH PRESSURE  
PUSHING INTO CENTRAL ILLINOIS LATER SATURDAY, WINDS WILL BE MUCH  
LIGHTER FROM A NORTH TO NORTHEAST DIRECTION, BUT STILL AVERAGE  
FROM 10 TO 15 KTS WITH A FEW AFTERNOON GUSTS UP TO 20 KTS,  
ESPECIALLY ACROSS THE EAST.  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
FREEZE WARNING UNTIL 9 AM CDT THIS MORNING FOR ILZ027>031-  
036>038-040>057-061>063-066>068-071>073.  
 

 
 

 
 
SHORT TERM...BARNES  
LONG TERM...BARNES  
AVIATION...SMITH  
 
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