Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 190828
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
328 AM CDT SUN APR 19 2015

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 328 AM CDT SUN APR 19 2015

LATEST WATER VAPOR IMAGERY CONTINUES TO SHOW CLOSED UPPER LOW OVER
EASTERN COLORADO, WITH LEAD SHORT-WAVE ROTATING AROUND THIS FEATURE
ACROSS ARKANSAS/LOUISIANA.  AS THIS WAVE LIFTS NORTHWARD, PRECIP
WILL EVENTUALLY SPREAD INTO CENTRAL ILLINOIS TODAY.  07Z/2AM RADAR
MOSAIC SHOWS DRY CONDITIONS ACROSS THE ENTIRE KILX CWA: HOWEVER,
SHOWERS ARE BEGINNING TO DEVELOP AND BECOME MORE WIDESPREAD FURTHER
SOUTH ACROSS WESTERN KENTUCKY AND FAR SOUTHERN ILLINOIS.  BASED ON
RADAR TIMING TOOLS AND LATEST HRRR FORECAST, THINK SCATTERED SHOWERS
WILL ARRIVE SOUTH OF I-70 OVER THE NEXT COUPLE OF HOURS, THEN WILL
SPREAD NORTHWARD TOWARD THE I-74 CORRIDOR BY MIDDAY.  HAVE ADJUSTED
POPS TO ACCOUNT FOR THE SLOWER ARRIVAL OF PRECIP DURING THE MORNING,
THEN HAVE GONE WITH CATEGORICAL POPS ACROSS THE BOARD THIS
AFTERNOON.  ASIDE FROM SOME SBCAPES OF AROUND 1000J/KG ACROSS THE
FAR SE CWA, FORECAST SOUNDINGS REMAIN FAIRLY STABLE TODAY.  AS A
RESULT, AM EXPECTING MAINLY SHOWERS WITH JUST A FEW EMBEDDED
THUNDERSTORMS.  DUE TO CLOUD COVER AND PRECIP, HIGH TEMPERATURES
WILL BE SEVERAL DEGREES COOLER THAN IN RECENT DAYS, WITH READINGS
MAINLY IN THE 60S.  WARMEST TEMPS OF AROUND 70 WILL BE FOCUSED
ALONG/WEST OF THE ILLINOIS RIVER WHERE PRECIP WILL BE SLOWEST TO
ARRIVE.

&&

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 328 AM CDT SUN APR 19 2015

LEAD SHORT-WAVE WILL LIFT INTO NORTHERN ILLINOIS/INDIANA BY EARLY
EVENING, LIKELY LEADING TO A TEMPORARY LULL IN THE SHOWERS.
MEANWHILE, THE MAIN UPPER LOW WILL GET A SOLID PUSH EASTWARD AND
WILL ARRIVE ACROSS ILLINOIS LATER TONIGHT INTO MONDAY MORNING.
SHOWERS AND PERHAPS A THUNDERSTORM WILL ACCOMPANY THIS FEATURE, SO
WILL CONTINUE LIKELY POPS TONIGHT THROUGH MONDAY MORNING.  ONCE THE
500MB VORT MAX AND THE ASSOCIATED SURFACE COLD FRONT PASS TO THE
EAST, RAIN CHANCES WILL COME TO AN END BY MONDAY AFTERNOON.  THANKS
TO A TIGHT PRESSURE GRADIENT BEHIND THE DEPARTING FRONT, STRONG W/NW
WINDS GUSTING TO BETWEEN 25 AND 30 MPH WILL DEVELOP ON MONDAY.  THE
WINDS WILL SUBSIDE FOR A TIME MONDAY NIGHT, BUT WILL ONCE AGAIN
INCREASE MARKEDLY DURING THE DAY TUESDAY.  HIGH TEMPERATURES BOTH
DAYS WILL REMAIN IN THE LOWER 60S, WHILE OVERNIGHT LOWS DIP INTO THE
UPPER 30S AND LOWER 40S.

00Z APR 19 MODELS HAVE COME INTO MUCH BETTER AGREEMENT CONCERNING
THE EXTENDED FORECAST, WITH CONSENSUS FEATURING A CHILLY AND LARGELY
DRY WEEK AHEAD.  BOTH THE GFS AND ECMWF INDICATE A WEAK COLD FRONT
WILL PASS THROUGH CENTRAL ILLINOIS TUESDAY NIGHT INTO WEDNESDAY:
HOWEVER, THEY DISAGREE ON HOW MUCH PRECIP IT WILL GENERATE.  THE GFS
IS SLIGHTLY WETTER AND FASTER WITH FROPA, WHILE THE ECMWF IS DRIER
AND ABOUT 6 HOURS SLOWER WITH THE FRONT.  DUE TO THE STRONG
NORTHWESTERLY UPPER FLOW PATTERN IN PLACE ACROSS THE MIDWEST, THINK
THE FASTER GFS IS THE WAY TO GO WITH TIMING, BUT THINK THE DRIER
ECMWF IS BETTER WITH QPF AS DEEP MOISTURE WILL BE LACKING WITH THIS
FEATURE.  AS A RESULT, HAVE OPTED TO CARRY LOW CHANCE POPS
EVERYWHERE TUESDAY NIGHT, THEN ONLY ACROSS THE SE CWA ON WEDNESDAY.
ONCE THE FRONT PASSES, A COOL/CANADIAN AIRMASS WILL SETTLE INTO THE
REGION FOR THE MIDDLE AND END OF THE WEEK.  HIGH TEMPERATURES WILL
STRUGGLE TO REACH THE 60 DEGREE MARK ON BOTH WEDNESDAY AND THURSDAY,
WHILE LOWS DROP INTO THE 30S.  COLDEST MORNING MAY END UP BEING
FRIDAY MORNING, WHEN RIDGE OF HIGH PRESSURE IS OVERHEAD AND WINDS
WILL BE LIGHTEST.  WILL NEED TO KEEP AN EYE ON TEMPS, AS FROST
ADVISORIES WILL BE POSSIBLE ACROSS PARTS OF CENTRAL/SOUTHEAST
ILLINOIS LATER THIS WEEK.  AFTER THAT, ANOTHER SYSTEM WILL APPROACH
FROM THE SOUTHWEST BY THE END OF THE WEEK: HOWEVER, ITS INFLUENCE
LIKELY WILL NOT BE FELT UNTIL FRIDAY NIGHT/SATURDAY AT THE EARLIEST.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1145 PM CDT SAT APR 18 2015

VFR CONDITIONS CONTINUE ACROSS CENTRAL IL TAF SITES THIS EVENING
AS A COMPLEX PATTERN OF A LARGE SCALE CENTRAL U.S. TROUGH WITH
MULTIPLE EMBEDDED DISTURBANCES DEVELOPS. MAINLY VFR CONDITIONS
EXPECTED UNTIL AROUND 12Z WHEN THE FIRST EMBEDDED DISTURBANCE
LIFTS NORTHEASTWARD INTO SE ILLINOIS. EXPECT INCREASING
PRECIPITATION AT SOUTHERN TERMINALS KSPI-KDEC AROUND 10Z SPREADING
NORTH TO KPIA-KBMI-KCMI AROUND 12Z. BY 14-16Z...PREDOMINANT RAIN
WITH MVFR CIGS/VSBYS LIKELY AND INCLUDED IN TAFS. ISOLATED
THUNDERSTORMS POSSIBLE AS WELL...BUT LIKELIHOOD/TIMING NOT HIGH
ENOUGH FOR EXPLICIT MENTION THIS FAR OUT. BRIEFLY IMPROVING
CONDITIONS LATE AFTERNOON EARLY EVENING AS FIRST DISTURBANCE MOVES
OUT OF CENTRAL IL...BUT TRAILING WAVE/COLD FRONT EXPECTED TO
INITIATE ADDITIONAL SHOWERS/THUNDERSTORMS TOWARD 06Z. WITH A
NARROW WINDOW OF UNCERTAIN IMPROVEMENT...KEPT MVFR CIGS/VSBYS
THROUGH 06Z. WINDS E-NE5-10 KTS THROUGH 15Z BECOMING VARIABLE-
NNW DURING AFTERNOON AS LOW LIFTS TO THE NE OF CENTRAL IL AREA.


&&

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

$$

SHORT TERM...BARNES
LONG TERM...BARNES
AVIATION...ONTON


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