949  
FXUS63 KILX 231955  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
255 PM CDT WED APR 23 2014  
   
DISCUSSION
 
 
ISSUED 253 PM CDT WED APR 23 2014  
 
PLENTY OF DRY AIR IN PLACE OVER ILLINOIS EARLY THIS AFTERNOON, ON  
THE PERIPHERY OF A HIGH PRESSURE RIDGE, WITH DEW POINTS IN THE  
UPPER 20S TO LOWER 30S. ACROSS THE SOUTHEAST HALF OF THE FORECAST  
AREA, CLOUDS HAVE BEEN ERODING AS THEY MOVE INTO THE DRIER AIR. AREA  
OF SHOWERS HAS BEEN ADVANCING EASTWARD FROM IOWA. LOOKS IMPRESSIVE  
ON RADAR, BUT SURFACE OBSERVATIONS ARE SHOWING CLOUD HEIGHTS WELL  
OVER 8000 FEET IN MANY CASES, INDICATING NOT MUCH IN THE WAY OF  
MEASURABLE RAIN IS REACHING THE GROUND. HOWEVER, THIS IS ENOUGH  
THAT A MENTION OF ISOLATED SHOWERS ACROSS THE NORTHERN CWA THIS  
EVENING IS WARRANTED.  
 
THE FIRST FORECAST CONCERN IS WITH THE TIMING OF RAIN OVER THE  
NEXT DAY OR SO, AS THIS STORM SYSTEM PUSHES EASTWARD. IN THE  
LONGER TERM, THE DURATION OF THE RAIN IS A CONCERN AS WE GET SET  
IN A RAINY PATTERN FOR THE FIRST HALF OF NEXT WEEK.  
 
SHORT TERM...TONIGHT THROUGH FRIDAY:  
 
WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS SHOWING A DEEP TROUGH  
CURRENTLY PUSHING EAST ACROSS THE ROCKIES, AND IS PROGGED TO MOVE  
ACROSS THE MISSISSIPPI VALLEY LATE THURSDAY. THE DRY AIR AT THE  
LOWER LEVELS WILL TAKE SOME TIME TO SATURATE, WITH THE FORECAST  
SOUNDINGS STILL RATHER PARCHED BELOW 850 MB AT MID AFTERNOON. HAVE  
LIMITED THURSDAY MORNING POP'S TO AREAS WEST OF I-55 AND STILL  
KEPT THEM BELOW 50% DURING THE AFTERNOON EAST OF I-57, OTHERWISE  
HAVE MAINTAINED THE CATEGORICAL POP'S OVER 80% IN MUCH OF THE  
FORECAST AREA DURING THE AFTERNOON. BEST INSTABILITY LOOKS TO BE  
ALONG AND SOUTH OF I-72 FOR ANY THUNDER, ALTHOUGH SOME LOW CAPE'S  
TO AROUND 200 J/KG PROGGED AS FAR NORTH AS PEORIA, SO HAVE KEPT  
SOME THUNDER MENTION THAT FAR NORTH. WITH THE SYSTEM A BIT SLOWER,  
WILL MENTION 80% OR HIGHER POP'S INTO THE EVENING ACROSS THE EAST  
HALF OF THE FORECAST AREA INTO THE EVENING. DRY WEATHER THEN ON  
TAP FOR FRIDAY.  
 
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY:  
 
A COLD FRONT WILL PUSH SOUTHWARD THROUGH THE REGION FRIDAY NIGHT.  
BIG QUESTION WILL BE WHERE IT ENDS UP, AS IT WILL LIKELY NOT BE  
GOING ANYWHERE FOR AWHILE. MOST OF THE MODELS DO HAVE IT THROUGH  
THE FORECAST AREA BY EARLY SATURDAY, ALTHOUGH THE ECMWF AND GEM  
MODELS LINGER IT MORE TOWARD THE I-72 CORRIDOR. SATURDAY SHOULD BE  
DRY. HOWEVER, THE MAIN ACTION WILL BE LATER IN THE WEEKEND, AS ALL  
THE MODELS CONTINUE TO CLOSE OFF AN UPPER LOW OVER THE CENTRAL  
ROCKIES. THIS LOW WILL ONLY SLOWLY DRIFT EASTWARD, AND WILL LIKELY  
LINGER IN SOME FORM INTO THE MIDDLE OF NEXT WEEK.  
 
MOST OF SUNDAY SHOULD BE FAIRLY DECENT, WITH THE RAIN MOST LIKELY  
ACROSS THE WESTERN CWA DURING THE AFTERNOON. AFTER THAT, RAIN IS  
LIKELY ON AND OFF, WITH POP'S GRADUALLY DIMINISHING TUESDAY AND  
WEDNESDAY AS THE CUTOFF LOW SLOWLY WEAKENS. BY THIS POINT, AS THE  
CORE OF THE COLDER AIR SETTLES OVER THE MIDWEST, TEMPERATURES WILL  
BE A GOOD 15 OR SO DEGREES BELOW NORMAL, WITH HIGHS TUESDAY AND  
ESPECIALLY WEDNESDAY GENERALLY IN THE 50S.  
 
GEELHART  
 

 
   
AVIATION
 
 
ISSUED 1236 PM CDT WED APR 23 2014  
 
DRY AIR IN PLACE EXPECTED TO KEEP THE PRECIP OUT TO THE WEST FROM  
WORKING INTO THE TAF SITES MORE THAN POSSIBLY A SPRINKLE THIS  
AFTERNOON, SO KEEPING FROM MENTION AT THIS POINT. HOWEVER...WILL  
DROP FROM 10KFT CIGS TO 5KFT CIGS WITH THE MOISTURE ADVECTION  
OVERALL BY LATER THIS EVENING. VFR THROUGH THE FCST, BUT THE NEXT  
PROBLEM IS EXPECTED TOMORROW MORNING AS THE WAVE PUSHES SOME  
PRECIP TOWARDS THE FA. MUCH OF THE PRECIP IS EXPECTED TO HOLD OFF  
UNTIL MID MORNING IN THE WEST...AND A BIT LATER IN THE EAST...BUT  
MODELS ARE NOT CONSISTENT WITH TIMING OR COVERAGE EARLY.  
MENTIONING VCSH FOR THE MORNING TO START THE TREND...AND NEXT  
ISSUANCE WILL LIKELY SEE MORE OF A MENTION AND CONTEMPLATE THE  
TIMING/POTENTIAL FOR THUNDER.  
 
HJS  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
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