Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 270830
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
330 AM CDT THU AUG 27 2015

.SHORT TERM...(TODAY)
ISSUED AT 326 AM CDT THU AUG 27 2015

EARLY MORNING SURFACE MAP INDICATES HIGH PRESSURE OVER NORTH CENTRAL
ILLINOIS RESULTING IN A MOSTLY CLEAR SKY AND RATHER COOL
TEMPERATURES. IDEAL RADIATIONAL CONDITIONS UNDERNEATH THE LARGE FAIR
WEATHER SYSTEM THIS MORNING WITH THE MERCURY ALREADY DOWN TO 48
DEGREES HERE AT THE OFFICE IN LINCOLN WITH A FEW OTHER LOCATIONS
APPROACHING 50 DEGREES. TEMP-DEW POINT SPREADS DECREASING AS WELL
SO SOME PATCHY FOG WILL BE POSSIBLE EARLY THIS MORNING WITH ANY
FOG DISSIPATING QUICKLY AS TEMPERATURES WARM RAPIDLY THRU THE
MORNING HOURS. FORECAST SOUNDINGS SUGGEST SOME CLOUDS DEVELOPING
AGAIN LATE THIS MORNING INTO THIS AFTERNOON, ESPECIALLY OVER THE
EASTERN HALF OF THE FORECAST AREA. HOWEVER, WE ARE NOT EXPECTING AS
MUCH CLOUDINESS AS WE SAW YESTERDAY WHICH SHOULD KEEP TEMPERATURES
MORE UNIFORM OVER CENTRAL ILLINOIS WITH HIGHS RANGING FROM THE
MID 70S FAR EAST TO AROUND 80 ACROSS THE REMAINDER OF THE FORECAST
AREA.

&&

.LONG TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 326 AM CDT THU AUG 27 2015

TEMPERATURES CLOSE TO CLIMATOLOGICAL NORMS TONIGHT AND TOMORROW AS
STORM SYSTEM TAKES SHAPE AND MOVES INTO THE REGION.  WAVE IS
CURRENTLY OVER THE NORTHERN ROCKIES AND IS SLIDING THROUGH THE
PLAINS AND INTO THE MIDWEST TO BRING INCREASING CHANCES FOR PRECIP
FOR FRI NIGHT AND SATURDAY.  ALTHOUGH THE MODELS ARE DOING BETTER
WITH THE TIMING OF THE WAVE, THE SOUTHERN EXTENT OF THE BETTER
PRECIP COVERAGE IS STILL BEING CALLED INTO QUESTION. A DRY AIRMASS
OVERALL ON ILX SOUNDINGS IS PART OF THE PROBLEM.  ALTHOUGH THE SFC
WINDS BECOME MORE SOUTHERLY THROUGH THE DAY ON FRIDAY, THE MOISTURE
ADVECTION IS LIMITED BY LIGHTER WINDS TO THE SOUTH.  THE MODELS HAVE
BEEN TRENDING THE WAVE A LITTLE FURTHER NORTH IN THE LATEST RUNS AS
WELL.  STILL CONCERNED THAT THE PRECIP WILL STILL BE MORE
INTERMITTENT THAN WIDESPREAD ALONG THE FRONTAL PASSAGE...WITH WEAKER
CONVERGENCE ALONG THE BOUNDARY.  GFS AND NAM STARTING TO TREND THAT
WAY, LINGERING THE PRECIP INTO SAT NIGHT AND IN THE EAST FOR EARLY
SUNDAY MORNING.

WAVE MOVING THROUGH EFFECTIVELY SHIFTS THE NORTHWESTERLY FLOW TO A
MORE SOUTHWESTERLY FROM THE SOUTHERN PAC COAST INTO THE HUDSON BAY
REGION...AND RATHER WEAK FLOW ALOFT FOR MOST OF THE EASTERN HALF
OF THE COUNTRY AFTER THE WEEKEND. HOT TEMPS UNDER THE RIDGE IN THE
SOUTHWESTERN CONUS DIFFUSE INTO THE REGION WITH THE PATTERN SHIFT
AND TEMPS THROUGH THE MIDDLE OF NEXT WEEK SIGNIFICANTLY ABOVE
NORMALS WITH MAX TEMPS APPROACHING THE 90 MARK BEFORE MIDWEEK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1149 PM CDT WED AUG 26 2015

THE LATEST FEW RUNS OF THE HRRR HAVE INTRODUCED LOCALLY DENSE FOG
ACROSS EASTERN AREAS OF CENTRAL IL. BMI AND CMI APPEAR TO HAVE THE
BETTER POTENTIAL FOR DENSE FOG, WITH MVFR FOG FOR DEC, SPI AND
PIA. THE FOG POTENTIAL APPEARS REASONABLE DUE TO IDEAL RADIATIONAL
COOLING CONDITIONS, AND AFTERNOON MIN DEWPOINTS WITHIN A COUPLE
DEGREES OF FORECAST LOWS. WILL INTRODUCE TEMPO GROUPS FOR FOG IN
ALL TAFS FOR LATE TONIGHT.

AFTER THE FOG BURNS OFF, MODEL SOUNDINGS SHOW THAT SOME PATCHY
CUMULUS ARE EXPECTED IN THE EASTERN PORTIONS OF OUR FORECAST AREA,
CLOSER TO BMI AND CMI. NO MVFR CEILINGS ARE EXPECTED.

WINDS WILL REMAIN LIGHT AND VARIABLE FOR THE REST OF THE NIGHT AS
THE SURFACE RIDGE AXIS LINGERS FROM NE TO SW ACROSS ILLINOIS.
SOUTHEAST WINDS WILL DEVELOP THURSDAY MORNING AS THE RIDGE AXIS
MOVES EAST OF OUR COUNTIES. HOWEVER, WIND SPEEDS SHOULD PREVAIL AT
LESS THAN 1OKT THROUGH THE DAY.


&&

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

$$

SHORT TERM...SMITH
LONG TERM...HJS
AVIATION...SHIMON


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