088  
FXUS63 KILX 021529  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
1029 AM CDT TUE SEP 2 2014  
   
UPDATE
 
 
ISSUED AT 1028 AM CDT TUE SEP 2 2014  
 
15Z/10AM SURFACE ANALYSIS SHOWS COLD FRONT WEST OF THE ILLINOIS  
RIVER, WITH WIDESPREAD CLOUDS BLANKETING MUCH OF CENTRAL AND  
SOUTHEAST ILLINOIS. SCATTERED SHOWERS ARE ONGOING ALONG/SOUTH OF  
I-70, WHILE ISOLATED RADAR RETURNS HAVE BEEN NOTED FURTHER NORTH  
UNDER THE LOW CLOUD DECK. WITH FRONT MAKING ONLY SLOW PROGRESS  
EASTWARD, HAVE ADJUSTED POPS TO CARRY ISOLATED SHOWERS EAST OF  
I-55 THROUGH EARLY AFTERNOON AND SCATTERED SHOWERS THROUGHOUT THE  
AFTERNOON FURTHER EAST AND SOUTH. HAVE ALSO ADJUSTED SKY GRIDS TO  
INDICATE A SLOWER WEST-TO-EAST CLEARING TREND. WITH MORE CLOUD  
COVER AROUND THAN PREVIOUSLY FORECAST, THINK AFTERNOON HIGHS WILL  
BE A COUPLE OF DEGREES COOLER AS WELL. HAVE LOWERED THEM MAINLY  
INTO THE LOWER 80S. SKIES WILL EVENTUALLY CLEAR OUT TONIGHT, AND  
WITH LIGHT WINDS BENEATH WEAK SURFACE RIDGE, THINK FOG WILL  
DEVELOP AFTER MIDNIGHT. 12Z NAM FORECAST SOUNDINGS SUGGEST THE  
MOST WIDESPREAD FOG MAY BE CONCENTRATED ACROSS THE E/SE KILX CWA,  
WHERE SKIES WILL BE SLOWEST TO CLEAR THIS AFTERNOON. AS A  
RESULT, HAVE ADDED AREAS OF FOG ALONG/EAST OF I-57 TONIGHT, WITH  
PATCHY FOG FURTHER WEST ACROSS THE REMAINDER OF THE AREA.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 406 AM CDT TUE SEP 2 2014  
 
SURFACE COLD FRONT MOVING INTO CENTRAL ILLINOIS EARLY THIS MORNING  
WITH LIGHT SHOWER ACTIVITY ALONG THE FRONT FROM AROUND PEORIA TO  
PONTIAC. HEAVY RAINFALL AND THUNDERSTORMS AFFECTING AREAS FROM  
AROUND I-72 SOUTHWARD WITH THE ACTIVITY GRADUALLY SHIFTING INTO FAR  
SOUTHERN ILLINOIS ALONG A CORRIDOR OF HIGH PRECIPITABLE WATER AROUND  
2 INCHES WITH A STRONG LOW LEVEL JET AND CONVERGENCE. RADAR  
INDICATES A SWATH OF AROUND 4-5 INCHES OF RAIN HAS FALLEN THIS  
EVENING FROM JUST SOUTH OF EFFINGHAM TO ROBINSON. CURRENT RADAR  
INDICATES SCATTERED RAINFALL RATES IN EXCESS OF 1 INCH PER HOUR ARE  
NOW CONFINED TO JASPER, CRAWFORD, RICHLAND, AND LAWRENCE COUNTIES  
AND AREAS TO THE SOUTH AND EAST...AND TRENDING SOUTHEASTWARD. A  
NUMBER OF FLASH FLOOD WARNINGS AS WELL AS A FLASH FLOOD WATCH AND A  
FLOOD ADVISORY CONTINUE IN THIS AREA. THIS ACTIVITY SHOULD CONTINUE  
THROUGH AROUND 7 A.M. WITH LINGERING SHOWERS AND THUNDERSTORMS  
CONTINUING TO SUBSIDE THROUGH THE AFTERNOON AS THE SYSTEM  
RESPONSIBLE MOVES EASTWARD.  
 
COOL AND DRY CONDITIONS EXPECTED TONIGHT AS DRY AIR AND SUBSIDENCE  
MOVES OVER CENTRAL ILLINOIS IN THE POST FRONTAL ENVIRONMENT.  
 

 
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 406 AM CDT TUE SEP 2 2014  
 
THE FRONTAL BOUNDARY IS EXPECTED TO RETURN NORTH AS A WARM FRONT IN  
MISSOURI AND WESTERN IL DURING WEDNESDAY. THE 00Z MODEL GUIDANCE HAS  
TRENDED A BIT QUICKER WITH A SHORT WAVE MOVING OUT OF MO INTO IL WED  
AFTERNOON AND INTO IN WED EVENING. BEST CHANCES OF CONVECTION STILL  
APEARS TO BE OVER SW IL INTO MO WHERE BETTER 850 MB LOW LEVEL JET  
WILL BE AND MORE MOISTURE TRANSPORT. CONFINED POPS TO AREAS FROM  
I-74 SW ON WED. WARMER AND MORE HUMID AIR STARTING TO RETURN BACK TO  
CENTRAL/SE IL WITH HIGHS IN THE MID TO UPPER 80S AND DEWPOINTS  
ELEVATING INTO THE UPPER 60S AND LOWER 70S WED AFTERNOON AND  
HIGHEST IN SW COUNTIES.  
 
HAVE 20-30% CHANCE OF SHOWERS AND THUNDERSTORMS OVER NORTHERN  
COUNTIES BY IL RIVER VALLEY WED NIGHT MAINLY AFTER MIDNIGHT AS THE  
INSTABILITY AXIS, THERMAL RIDGE, AND NOSE OF THE 850MB LLJ ADVANCE  
TOWARD NORTHWEST IL. THU STILL APPEARS TO BE THE WARMEST DAY THIS  
WEEK WITH HIGHS IN THE UPPER 80S AND LOWER 90S AND DEWPOINTS IN THE  
LOW TO MID 70S WITH BREEZY SW WINDS AND WELL ENTRENCHED IN THE WARM  
SECTOR. PEAK AFTERNOON HEAT INDICES MAY REACH INTO THE UPPER 90S TO  
AROUND 100F ON THU. MOST AREAS SHOULD BE DRY THU WITH JUST ISOLATED  
CONVECTION NEAR THE WABASH RIVER THU AFTERNOON.  
 
LOW PRESSURE DEEPENING NE FROM THE NORTHERN PLAINS TO NORTH OF THE  
GREAT LAKES WILL DRAG A COLD FRONT INTO THE IL RIVER VALLEY EARLY  
FRIDAY MORNING AND INTO SOUTHERN ILLINOIS BY FRIDAY EVENING. HAVE  
20-30% CHANCE OF SHOWERS AND THUNDERSTORMS AFTER MIDNIGHT THU NIGHT  
OVER THE IL RIVER VALLEY. THEN A GOOD CHANCE OF SHOWERS AND  
THUNDERSTORMS SPREADING SE ACROSS CENTRAL/SE IL DURING THE DAY  
FRIDAY AND CONTINUE FRIDAY NIGHT. STILL A VERY WARM AND HUMID DAY  
FRIDAY WITH HIGHS IN THE 80S AND DEWPOINTS IN THE UPPER 60S TO MID  
70S, WITH SOUTHEAST IL NEAR 90F SOUTHEAST OF I-70. LINGERED CHANCES  
OF SHOWERS AND THUNDERSTORMS SATURDAY SOUTH OF I-72, WITH  
DIMINISHING CHANCES IN SOUTHEAST IL DURING SATURDAY AFTERNOON AS  
FRONTAL BOUNDARY PUSHES SE INTO TN RIVER VALLEY.  
 
A SIGNIFICANT AIRMASS CHANGE WILL FOLLOW THAT FRONTAL PASSAGE, AS A  
1024 MB CANADIAN HIGH PRESSURE BUILDS SOUTHEAST INTO THE WESTERN  
GREAT LAKES. LESS HUMID AIR ALONG WITH COOLER HIGHS SUNDAY AND  
MONDAY IN THE 70S, WITH LOWS SATURDAY AND SUNDAY NIGHT IN THE 50S.  
THIS WILL BE THE COOLEST AIR SINCE MID AUGUST TO VISIT CENTRAL IL,  
THE LAST TIME WE HAD BELOW NORMAL TEMPERATURES.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)  
ISSUED AT 659 AM CDT TUE SEP 2 2014  
 
GENERALLY IFR CEILINGS ACROSS CENTRAL IL THIS MORNING AS HEAVY  
RAIN AND THUNDERSTORMS HAVE MOVED EAST OF THE AREA. LOW CLOUD  
COVER SHOULD LIFT AND DISSIPATE LATER THIS MORNING WITH SCATTERED  
LOW CLOUD COVER EXPECTED TO RESULT IN MAINLY VFR CONDITIONS ACROSS  
THE AREA BY 14Z. ISOLATED TSRA TO REDEVELOP AFTER 17Z FROM  
K1H2-KRSV SOUTHWARD COULD RESULT IN ISOLATED MVFR CIG/VSBY AND  
GUSTY WINDS UNTIL 00Z. 00Z-06Z MAINLY VFR CONDITIONS AND LIGHT  
WINDS. FOG LIKELY TO DEVELOP BY EARLY MORNING RESULTING IN IFR  
VISIBILITIES OR WORSE AND MANY LOCATIONS AFTER 06-09Z.  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...BARNES  
SHORT TERM...ONTON  
LONG TERM...07  
AVIATION...ONTON  
 
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