Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 050451
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1151 PM CDT MON MAY 4 2015

.UPDATE...
ISSUED AT 848 PM CDT MON MAY 4 2015

LATEST SURFACE ANALYSIS HAS A NEARLY STATIONARY FRONTAL BOUNDARY
CUTTING WEST TO EAST ACROSS CENTRAL ILLINOIS ROUGHLY FROM QUINCY
TO PARIS. THIS BOUNDARY IS FAIRLY WELL DELINEATED BY AN EXPANDING
FINE LINE OF SHOWERS AND ISOLATED THUNDERSTORMS. THE PREVIOUS
INTENSITY OF THE AREA OF STORMS PUSHING INTO WEST-CENTRAL ILLINOIS
HAS FADED WITH THE LOSS OF DIURNAL INSTABILITY WITH THE BULK OF
THE STORMS IN OUR VICINITY CURRENTLY OF THE "GARDEN VARIETY".

THE BULK OF THE GUIDANCE, ESPECIALLY RECENT RUNS OF MANY HIGH
RESOLUTION MODELS, SUGGEST THE BULK OF THE SHOWERS/STORMS THOUGH
THE NIGHT WILL EXIST ALONG/NORTH OF THE FRONTAL BOUNDARY. ALSO, A
WAVE LIFTING NORTHEAST OUT OF THE PLAINS IS EXPECTED TO HELP PUSH
THE FRONT A LITTLE FURTHER NORTH WITH TIME OVERNIGHT. THESE
FACTORS WOULD SUGGEST THE BULK OF THE UPSTREAM PRECIPITATION OVER
IOWA AND MISSOURI WOULD TRACK NORTH OF MOST OF THE FORECAST AREA.

PLAN TO UPDATE FORECAST TO REFINE POPS, MAINLY TO PUSH THE RISK
FURTHER NORTH. OTHERWISE, MINOR TWEAKS ARE NEEDED FOR THE LATEST
HOURLY TRENDS.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 245 PM CDT MON MAY 4 2015

FRONTAL BOUNDARY EXTENDING FROM SOUTHERN LAKE MICHIGAN TO NORTHERN
KANSAS WILL SINK SOUTHWARD...EVENTUALLY STALLING NEAR THE I-72
CORRIDOR LATER THIS EVENING.  SHOWERS AND THUNDERSTORMS WILL DEVELOP
ALONG THE BOUNDARY...WITH MOST MODEL SOLUTIONS SUGGESTING THE
GREATEST AREAL COVERAGE OF PRECIP ACROSS THE NORTHERN HALF OF THE
KILX CWA.  HRRR IS SHOWING WIDELY SCATTERED STORMS DEVELOPING OVER
THE NEXT COUPLE OF HOURS...WITH THE CONVECTION BECOMING MORE
WIDESPREAD AFTER SUNSET AS A WEAK LOW-LEVEL JET DEVELOPS.  HAVE
ADJUSTED RAIN CHANCES ACCORDINGLY...WITH LIKELY POPS ALONG/NORTH OF
I-72 TAPERING DOWN TO JUST SLIGHT CHANCE ALONG/SOUTH OF I-70.

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 245 PM CDT MON MAY 4 2015

AN UPPER LEVEL RIDGE IS EXPECTED TO AMPLIFY OVER THE CENTER OF THE
NATION STARTING ON TUESDAY WHICH SHOULD PUSH THE BETTER CHANCES FOR
SHOWERS AND THUNDERSTORMS NORTH OF THE FORECAST AREA...AT LEAST INTO
THURSDAY. SHORTWAVE ENERGY IS THEN FORECAST TO EJECTS NORTH OUT OF
THE SOUTHERN PLAINS AND BRING ABOUT A CHANCE FOR MORE SHOWERS AND
THUNDERSTORMS...ESPECIALLY ACROSS OUR WEST...THURSDAY NIGHT INTO
FRIDAY. A MORE POTENT 500 MB TROF IS THEN FORECAST TO SLOWLY TRACK
OUT OF THE ROCKIES DURING THE WEEKEND BRINGING PERIODS OF SHOWERS
AND THUNDERSTORMS TO THE FORECAST AREA. MOST MODELS TRACK THIS LOW
NORTH-NORTHEAST ON SUNDAY SUGGESTING THE MORE SIGNIFICANT LIFT TO
REMAIN WEST OF OUR AREA UNTIL LATE SUNDAY OR MONDAY OF NEXT WEEK
WHEN THE SYSTEM WILL SWING A COLD FRONT THROUGH CENTRAL ILLINOIS.
UNTIL THEN...WARM TEMPERATURES TO PREVAIL WITH THE SHOWER AND STORM
CHANCES ACROSS THE FAR NORTH TOMORROW AS THE FRONT RETREATS BACK
TO THE NORTH...AND THEN RAIN CHANCES RETURN LATE THU INTO FRIDAY
AND HOLDS THROUGH EARLY NEXT WEEK BEFORE WE FINALLY GET A CHANGE
IN AIR MASS.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1144 PM CDT MON MAY 4 2015

FAIRLY SMALL AREA OF SHOWERS AND EMBEDDED THUNDERSTORMS IS STILL
MAKING ITS WAY ACROSS CENTRAL ILLINOIS, AND THIS AREA IS ONLY A
THREAT AT KBMI AND KCMI FOR A FEW MORE HOURS. MORE WIDESPREAD
SHOWERS/STORMS ARE UPSTREAM FROM THE CENTRAL ILLINOIS TERMINAL
AREA. RECENT SHORT RANGE/HIGH RESOLUTION MODEL GUIDANCE, SUPPORTED
BY RADAR LOOPS, SUGGESTS THAT MUCH OF THIS PRECIPITATION WILL PASS
TO THE NORTH OF THE LOCAL TERMINALS. KPIA AND KBMI STAND THE BEST
CHANCE OF BEING IMPACTED BY THIS UPSTREAM PRECIPITATION FOR
SEVERAL MORE HOURS, WHILE KSPI, KDEC, AND KCMI WILL BE MOSTLY DRY.
OUTSIDE OF ANY APPRECIABLE RAINFALL AREAS, WHICH WILL BRIEFLY
PRODUCE MVFR CONDITIONS, VFR CONDTIONS SHOULD PREVAIL. MOST OF THE
REST OF THE NIGHT SHOULD SEE VARIABLE WINDS WITH A NEARLY
STATIONARY BOUNDARY IN THE VICINITY. EXPECT WINDS TO TREND
SOUTHWESTERLY TUESDAY MORNING AS THE FRONT SHIFTS BACK NORTH.

&&

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

$$

UPDATE...BAK
SHORT TERM...BARNES
LONG TERM...SMITH
AVIATION...BAK



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