Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 031943
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
243 PM CDT MON AUG 3 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 241 PM CDT MON AUG 3 2015

WEAK COLD FRONT CURRENTLY EXTENDING FROM CENTRAL INDIANA TO NORTHERN
MISSOURI WILL CONTINUE TO SAG SOUTHWARD THIS AFTERNOON AND
EVENING...EVENTUALLY STALLING NEAR THE OHIO RIVER.  CLUSTERS OF
THUNDERSTORMS HAVE BEEN ONGOING FOR MUCH OF THE DAY ALONG THE
BOUNDARY ACROSS NORTHERN MISSOURI...HOWEVER THESE CELLS ARE
GENERALLY TRACKING SOUTHEASTWARD AND WILL REMAIN W/SW OF THE KILX
CWA.  MEANWHILE...A CU-FIELD IS BEGINNING TO DEVELOP FURTHER EAST
ALONG THE FRONT ACROSS INDIANA WHERE THE HRRR/RAPID REFRESH SUGGEST
SCATTERED THUNDERSTORM DEVELOPMENT OVER THE NEXT COUPLE OF HOURS.
IN BETWEEN THESE TWO AREAS...MODELS ARE MOSTLY DRY ACROSS SOUTH-
CENTRAL ILLINOIS.  WILL HOLD ON TO JUST A SLIGHT CHANCE POP SOUTH OF
I-70 LATE THIS AFTERNOON IN CASE A STORM FIRES AHEAD OF THE
FRONT...BUT DO NOT SEE MUCH EVIDENCE OF THAT HAPPENING YET.  MODELS
ARE THEN SHOWING RENEWED CONVECTIVE DEVELOPMENT ALONG/NORTH OF THE
BOUNDARY ACROSS NORTHERN MISSOURI LATER TONIGHT...WITH SCATTERED
STORMS THEN TRACKING E/SE INTO SOUTH-CENTRAL ILLINOIS.  EXACTLY HOW
FAR NORTH INTO THE SLIGHTLY COOLER/DRIER AIRMASS THE PRECIP WILL
DEVELOP REMAINS IN QUESTION...WITH THE MOST RECENT RUNS OF THE RAPID
REFRESH SHOWING IT GENERALLY JUST S/SW OF THE CWA.  HAVE INCLUDED A
SLIGHT CHANCE POP ALONG/SOUTH OF A RUSHVILLE...TO TAYLORVILLE...TO
ROBINSON LINE AFTER MIDNIGHT...BUT THINK MOST AREAS WILL REMAIN DRY.

&&

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 241 PM CDT MON AUG 3 2015

MAIN FORECAST CONCERN FOR THIS PART OF THE FORECAST WILL BE WITH
RAIN TRENDS FOR THE MIDDLE OF THE WEEK.

LATEST WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS SHOWS A SMALL
UPPER LOW OVER NORTHERN UTAH...TRYING TO PUNCH THROUGH THE RIDGE
THAT IS OTHERWISE PREVAILING ALONG THE ROCKIES. MOST OF THE MODELS
MANAGE TO SLIP A PIECE OF THIS ENERGY THROUGH THE RIDGE AND INTO THE
PLAINS ON TUESDAY. THIS IS EXPECTED TO INTERACT WITH THE COLD FRONT
CURRENTLY SINKING SOUTHWARD ACROSS SOUTHERN MISSOURI INTO THE
OHIO VALLEY. THE NAM AND GFS MODELS ALSO EJECT SOME ENERGY INTO
THE DAKOTAS...HOWEVER THE GFS IS ALONE IN MAKING THAT THE
DOMINANT FEATURE AND PULLING THE FRONT BACK NORTH ACROSS MOST OF
ILLINOIS BY MIDDAY WEDNESDAY. MOST OF THE GUIDANCE FOCUSES THE
ENERGY NEAR THE EXISTING FRONTAL BOUNDARY POSITION...LIFTING THE
BOUNDARY NORTHWARD TO JUST SOUTH OF I-72 BY WEDNESDAY
EVENING...BEFORE AN AREA OF LOW PRESSURE FORMS IN MISSOURI AND
TRACKS ACROSS SOUTHERN ILLINOIS. DISCOUNTING THE GFS...WILL
CONTINUE TO FOCUS THE HIGHER POP`S ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA...WITH LIKELY POP`S EDGING IN FROM THE SOUTHWEST
WEDNESDAY AND ACROSS A GOOD PORTION OF CENTRAL AND SOUTHEAST
ILLINOIS BY WEDNESDAY NIGHT. HEAVIEST RAINS WILL BE CONCENTRATED
NEAR THE LOW TRACK...WHICH HAS SLIPPED A BIT FURTHER SOUTH FROM
EARLIER FORECASTS...AND HAVE CONFINED THE 1 TO 2 INCH RAINFALL
PROJECTIONS TO AREAS SOUTH OF I-70. THE RAIN WILL BE TAPERING OFF
FROM WEST TO EAST THURSDAY MORNING...AS THE LOW MOVES INTO
SOUTHERN INDIANA.

THE UPPER PATTERN LATE IN THE WEEK CONTINUES TO FLATTEN THE RIDGE
SOME...ALLOWING FOR A SERIES OF WAVES TO BE TRACKING ACROSS THE
UPPER MISSISSIPPI VALLEY. LONGER RANGE GUIDANCE IS IN POOR AGREEMENT
REGARDING THE STRENGTH OF THESE WAVES...LEADING TO LOWER THAN NORMAL
CONFIDENCE IN THIS PART OF THE FORECAST. SOME EVIDENCE OF THE RIDING
STARTING TO BUILD AGAIN LATE IN THE WEEKEND ACROSS THE PLAINS...
SETTING UP SOME POTENTIAL FOR MCS ACTIVITY...SO WILL INCLUDE SOME
MENTIONABLE RAIN CHANCES SUNDAY NIGHT.

TEMPERATURES EXPECTED TO BE BELOW NORMAL MUCH OF THE PERIOD...WITH
HIGHS IN THE 80 DEGREE VICINITY...AND EVEN COOLER THAN THAT
THURSDAY/FRIDAY BEHIND THE UPCOMING STORM SYSTEM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1242 PM CDT MON AUG 3 2015

VFR CONDITIONS WILL PREVAIL THROUGH THE ENTIRE 18Z TAF PERIOD. A
COLD FRONT WILL DROP SOUTH OF THE TERMINALS THIS AFTERNOON...THEN
WILL BECOME NEARLY STATIONARY ACROSS SOUTHERN ILLINOIS TONIGHT
INTO TUESDAY. W/NW WINDS OF 8 TO 12KT THIS AFTERNOON WILL BECOME
LIGHT/VARIABLE TONIGHT AS HIGH PRESSURE BUILDS INTO THE REGION.
WHILE THE FRONT WILL REMAIN WELL TO THE SOUTH...MOST MODELS ARE
SUGGESTING SCATTERED SHOWERS/THUNDER WILL DEVELOP NEAR THE
BOUNDARY LATE TONIGHT. THINK PRECIP WILL STAY S/SW OF THE TAF
SITES...BUT HAVE INCLUDED A MID-LEVEL CLOUD DECK AT KSPI AFTER 09Z
ACCORDINGLY.


&&

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

$$

SHORT TERM...BARNES
LONG TERM...GEELHART
AVIATION...BARNES



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