Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 242333
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
633 PM CDT FRI APR 24 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 308 PM CDT FRI APR 24 2015

STORM SYSTEM APPROACHING THE MIDWEST FROM THE WEST OVERNIGHT
SPREADING PRECIPITATION AHEAD OF IT AND SETTING UP A LONGER DURATION
RAINFALL EVENT.  CLOUDS AND SOUTHEASTERLY WINDS KEEPING THE REGION
CONSIDERABLY WARMER THAN THE PAST COUPLE OF NIGHTS, BUT PRECIP
ACCOMPANYING AS WELL.  ISOLATED THUNDER CANNOT BE RULED OUT
PARTICULARLY AFTER MIDNIGHT AS THE LOW CENTER DRAWS NEARER. ROUGHLY
A HALF AN INCH OR SO OF PRECIPITATION POSSIBLE BEFORE 7 AM.

.LONG TERM...(SATURDAY THROUGH FRIDAY)
ISSUED AT 308 PM CDT FRI APR 24 2015

LOW PRESSURE CENTER ASSOCIATED WITH THE STORM SYSTEM CURRENTLY
EJECTING NORTHEAST OUT OF NEW MEXICO WILL REACH NEAR THE IL/MO
BORDER BETWEEN ST LOUIS AND QUINCY AROUND NOON SATURDAY...WITH A
WARM FRONT EXTENDING ESE FROM THE LOW TO ROUGHLY NEAR THE I-64
CORRIDOR. THE LOW WILL THEN TRACK ESE ACROSS IL THROUGH SATURDAY
EVENING. ROUGHLY 30-45 KTS OF 0-6 KM BULK SHEAR AND MUCAPE
INSTABILITY VALUES AROUND 1500-2000 JOULES SHOULD DEVELOP IN THE
WARM SECTOR SOUTH OF THE WARM FRONT...WITH MUCH MORE MODEST VALUES
TO THE NORTH AS WELL AS A LACK OF SURFACE-BASED INSTABILTY. VALUES
ALONG/SOUTH OF THE WARM FRONT SHOULD BE ENOUGH TO SUPPORT STORMS
CAPABLE OF PRODUCING HAIL AND SEVERE WIND GUSTS AS WELL AS LOCALLY
HEAVY RAINFALL...POTENTIAL TORNADO DEVELOPMENT AS WELL...WHILE TO
THE NORTH MORE OF A STEADY MODERATE RAINFALL AND COOL TEMPERATURES
WOULD BE EXPECTED. MODELS FAIRLY CONSISTENT WITH THE TRACK OF THE
LOW AT THIS POINT...BUT SMALL ERRORS ON EXACT TRACK STILL PRESENTS
SOME UNCERTAINTY ON SEVERE THUNDERSTORM POSSIBILITIES IN THE
SOUTHERN PORTIONS OF THE CENTRAL/SE IL FORECAST AREA. STORM TOTAL
PRECIPITATION LOOKS TO BE AROUND 1-1.25 INCHES ACROSS THE CENTRAL/SE
IL FORECAST AREA...WITH LOCALLY HIGHER AMOUNTS POSSIBLE. HEAVIER
AREAS COULD INITIATE SOME RIVER FLOOD ISSUES.

THE LOW WILL THEN MOVE RAPIDLY EAST SATURDAY NIGHT WITH SHOWERS
COMING TO AN END FOR CENTRAL IL. COOL AND DRY NORTHERLY FLOW OUT OF
CANADA WILL FOLLOW THE SYSTEM FOR SUNDAY AND MONDAY...WITH HIGHS IN
THE UPPER 50S/LOW 60S AND LOWS DIPPING INTO THE 30S IN SOME
LOCATIONS.

A CENTRAL U.S. HIGH WILL BUILD TOWARD THE END OF THE WEEK PROMOTING
A WARMING TREND...GENERALLY DRY CONDITIONS...AND LIGHTER WINDS. A
WEAK TROUGH MIDWEEK AT THIS POINT LOOKS PROBABLY TOO DRY FOR
PRECIPITATION AS IT SPLITS INTO A STRONGER LOW OVER THE DEEP SOUTH
AND A SEPARATE WAVE PASSING FAR TO THE NORTH...BUT AT LEAST A SLIGHT
CHANCE FOR PRECIP IS NOT OUT OF THE QUESTION. HIGHS TUESDAY THROUGH
FRIDAY SHOULD RISE FROM THE MID-60S TUESDAY TO NEAR 70 FRIDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 625 PM CDT FRI APR 24 2015

MAIN FORECAST CONCERN WILL BE WITH TIMING OF MVFR AND LOWER CIGS
INTO CENTRAL AND EAST CENTRAL ILLINOIS LATER TONIGHT AS LOW
PRESSURE APPROACHES THE AREA. LATEST SHORT TERM FORECAST SOUNDINGS
SUGGEST A SLOWER TREND WITH LOWER CIGS FROM SOUTHWEST TO NORTHEAST
TONIGHT AS THE LOW LEVELS WILL BE SLOW TO SATURATE. IT APPEARS AS
SHOWERS DEVELOP TO OUR SOUTHWEST AROUND 04Z AND THEN TRACK INTO
OUR AREA DURING THE EARLY MORNING HOURS...CIGS WILL DETERIORATE
RAPIDLY ONCE THE MORE WIDESPREAD PRECIP BEGINS. BASED ON THE
CURRENT TRACK OF THE SURFACE LOW PRESSURE AREA ON SATURDAY...SOUTH
OF THE TAF SITES...IT APPEARS WE MAY BE STUCK IN MVFR TO
OCCASIONAL IFR CIGS INTO THE AFTERNOON. SURFACE WINDS WILL BE OUT
OF THE SOUTHEAST TONIGHT AT 10 TO 15 KTS WITH AN OCCASIONAL GUST
APPROACHING 20 KTS...WITH WINDS BACKING MORE INTO THE NORTHEAST
BY AFTERNOON AT 12 TO 17 KTS...WITH AGAIN A FEW GUSTS AROUND 20
KTS AT TIMES.

&&

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

$$

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


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