Area Forecast Discussion
Issued by NWS Central Illinois

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KILX 260444
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1144 PM CDT TUE AUG 25 2015

.UPDATE...
ISSUED AT 849 PM CDT TUE AUG 25 2015

QUIET WEATHER IS ANTICIPATED ACROSS CENTRAL AND SOUTHEAST ILLINOIS
OVERNIGHT AS HIGH PRESSURE BEGINS TO BUILD INTO THE AREA. HOWEVER,
MUCH LIKE LAST NIGHT, A SPOKE OF UPPER LEVEL ENERGY IS ROTATING
AROUND THE PESKY UPPER LEVEL LOW CENTERED OVER NORTHERN ONTARIO.
THIS DISTURBANCE IS CAUSING THE CLOUD COVER ASSOCIATED WITH THE
CIRCULATION TO BULGE SOUTH TOWARD THE FORECAST AREA. THIS LOW
CLOUD DECK CONTINUES TO NOT BE MODELED VERY WELL BY MOST
GUIDANCE, AGAIN MUCH LIKE LAST NIGHT. EXTRAPOLATION OF THE CLOUDS
BASED ON RECENT SATELLITE LOOPS SUGGEST PORTIONS OF THE FORECAST
AREA ALONG/NORTH OF THE I-74 CORRIDOR WILL SEE A PERIOD OF MOSTLY
CLOUDY SKIES TONIGHT. THESE CLOUDS MAY HANG ON LONG ENOUGH TO HOLD
LOW TEMPERATURES UP A BIT ACROSS FAR NORTHERN PORTION OF THE
FORECAST AREA. PLAN TO UPDATE FORECAST PRIMARILY FOR THE EXPECTED
CLOUD TRENDS, BUT ALSO FOR THE OTHER NIGHTTIME HOURLY TRENDS.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 300 PM CDT TUE AUG 25 2015

LARGE UPPER LOW CONTINUES TO SPIN ACROSS EASTERN ONTARIO...WITH
LARGE STRATOCUMULUS DECK SOUTH ACROSS THE GREAT LAKES. SOME DIURNAL
DEVELOPMENT HAS TAKEN PLACE ALONG THE SOUTHERN FLANK...EXTENDING AS
FAR SOUTH AS KENTUCKY. MOST OF THIS SHOULD FADE AWAY WITH SUNSET...
BUT MAY TAKE A BIT LONGER ACROSS THE FAR NORTHERN PARTS OF THE
FORECAST AREA. WITH DEW POINTS CURRENTLY IN THE MID 40S TO LOWER
50S... ANOTHER PLEASANTLY COOL NIGHT IS ON TAP...WITH MOST LOCATIONS
SEEING LOWS IN THE LOWER 50S.

.LONG TERM...(WEDNESDAY THROUGH TUESDAY)
ISSUED AT 300 PM CDT TUE AUG 25 2015

557 DM 500 MB LOW OVER EASTERN ONTARIO CLOSE TO QUEBEC PROVINCE LINE
TO GRADUALLY LIFT NE ACROSS QUEBEC NEXT FEW DAYS. 500 MB HEIGHTS
OF 579-582DM OVER CENTRAL IL TODAY TO INCREASE TO 583-586DM BY THU
AFTERNOON INTO FRI MORNING. 1020 MB SURFACE HIGH PRESSURE RIDGE
OVER THE CENTRAL PLAINS TO DRIFT EAST OVER IL BY 12Z/THU.
CENTRAL/SE IL STILL CAUGHT UP IN CYCLONIC FLOW ANOTHER DAY ON WED
WITH FEW-SCT CUMULUS CLOUDS NE CWA WED AFTERNOON NNW WINDS NOT AS
GUSTY AS TODAY AND YESTERDAY AS HIGH PRESSURE NEARS IL. HIGHS IN
THE MID TO UPPER 70S WED AND UPPER 70S TO NEAR 80F ON THU.
COMFORTABLE DEWPOINTS IN THE 50S WED/THU. STAYED CLOSE TO SIMILAR
GUIDANCE FOR HIGHS NEXT FEW DAYS AND SIDED TOWARD COOLER LOWS IN
LOW TO MID 50S WED NIGHT WITH HIGH PRESSURE MOVING IN AND LIGHT TO
CALM WINDS AND FAIR SKIES. LOWS THU NIGHT RANGE FROM MID 50S FROM
CHAMPAIGN/URBANA EAST AND LOWER 60S FROM IL RIVER WEST.

12Z FORECAST MODELS EJECT A SHORT WAVE TROF INTO THE MIDWEST BY
FRIDAY MORNING WITH MOST OF ITS QPF STILL NW OF CWA AT 18Z/FRI. THE
FORECAST CONUNDRUM WILL BE HOW STRONG AND HOW FAR SOUTH THIS FEATURE
GETS AS IT TRACK EAST INTO IL BY SAT. GFS AND ECMWF MODELS SHOW
SOME QPF NW OF IL RIVER FRI AFTERNOON AND WILL MAINTAINED SMALL
POPS OF 20-30% THERE MAINLY LATE FRI AFTERNOON. SKIES BECOME
PARTLY TO MOSTLY CLOUDY FRI WITH HIGHS MOSTLY IN THE LOWER 80S
WITH SOME UPPER 70S IN CLOUDIER AREAS BY GALESBURG. SSE WINDS ON
BACK SIDE OF SURFACE RIDGE DRIFTING OFF TO OUR EAST WILL BRING A
BIT HIGHER DEWPOINTS IN THE LOWER 60S FRI. SHORT WAVE TROF CLOSEST
TO IL ON SAT. SE IL LIKELY STAYS DRY FRI NIGHT YET WHILE SLIGHT
CHANCE IN EAST CENTRAL IL OVERNIGHT FRIDAY NIGHT AND 30-40% CHANCE
OF SHOWERS AND THUNDERSTORMS FRI NIGHT OVER NW HALF OF CWA.
CONTINUE 30-40% CHANCE SAT OVER CENTRAL IL WHILE 20% CHANCE IN
SOUTHEAST IL. GFS MODEL HAS TRENDED DRIER OVER CENTRAL IL ON SAT
WHILE ECMWF STILL HAS SOME QPF OVER AREA. HAVE 20-30% CHANCE SAT
NIGHT WITH HIGHEST POPS OVER EAST CENTRAL IL SAT EVENING. THEN
JUST SLIGHT CHANCE IN EASTERN IL SUNDAY. HIGHS SAT MOSTLY IN LOWER
80S, BUT RANGE FROM UPPER 70S BY GALESBURG TO MID 80S IN SE IL.

12Z MEDIUM/EXTENDED MODELS AND THEIR ENSEMBLES CONTINUE TO ADVERTISE
A GRADUAL WARMING AND INCREASING HUMIDITY TREND OVER THE WEEKEND
INTO EARLY NEXT WORK WEEK. THIS DUE TO UPPER LEVEL RIDGE OVER THE
ROCKIES (595 DM 500 MB HIGH OVER CO) BUILDS EAST TO THE GREAT LAKES
AND OHIO VALLEY EARLY NEXT WEEK. A WEAK UPPER DISTURBANCE WILL MOVE
EAST ACROSS REGION OVER THE WEEKEND. WILL MENTION LOW CHANCES OF
THUNDERSTORMS AROUND SATURDAY AND SLIGHT CHANCE POPS MOST AREAS
SUNDAY AND ACROSS THE EAST HALF MONDAY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1142 PM CDT TUE AUG 25 2015

QUIET/VFR AVIATION WEATHER CONDITIONS EXPECTED ACROSS THE CENTRAL
ILLINOIS TERMINALS THROUGH THE 06Z TAF VALID TIME. A RIDGE OF
HIGH PRESSURE WILL SLOWLY BUILD INTO THE AREA DURING THE PERIOD
HELPING WINDS TO REMAIN LIGHT. CLOUD COVER SHOULD BE MINIMAL
OVERALL, BUT A PERIOD OF BROKEN VFR CIGS IS POSSIBLE FOR A FEW
MORE HOURS KPIA, KBMI, KDEC & KCMI AS AN UPPER LEVEL DISTURBANCE
DIVES SOUTHEAST FROM THE GREAT LAKES.

&&

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

$$

UPDATE...BAK
SHORT TERM...GEELHART
LONG TERM...07
AVIATION...BAK


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.