Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 251100
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
600 AM CDT TUE AUG 25 2015

.SHORT TERM...(TODAY)
ISSUED AT 312 AM CDT TUE AUG 25 2015

DEEP UPPER TROF FOR LATE AUGUST SITUATED JUST NORTH OF LAKE HURON
EARLY THIS MORNING IS FORECAST TO SLOWLY EDGE EAST OVER THE NEXT FEW
DAYS. MEANWHILE...SEVERAL WEAK SHORTWAVES ROTATING SOUTHEAST INTO
THE LOWER GREAT LAKES WITH ONE SUCH FEATURE NOW PUSHING ACROSS SOUTH
CENTRAL LAKE MICHIGAN. THIS WAVE MAY HAVE BEEN RESPONSIBLE FOR
PUSHING THE STRATOCUMULUS DECK A BIT FURTHER SOUTH THAN ANTICIPATED
LATE YESTERDAY THROUGH EARLY THIS MORNING. AS THE WEAK UPPER LEVEL
DISTURBANCE PUSHES FURTHER OFF TO OUR EAST WE SHOULD SEE THE CLOUD
DECK CONTINUE THIN OUT ACROSS OUR NORTHERN COUNTIES. HOWEVER,
ADDITIONAL PIECES OF ENERGY ARE SEEN ROTATING SOUTHWARD AROUND THE
LARGE UPPER LOW AND THAT COMBINED WITH DAYTIME HEATING MAY LEAD TO A
LEAST SOME SCATTERED CLOUD COVER ACROSS THE NORTH LATER THIS MORNING
INTO THE AFTERNOON HOURS. RAP FORECAST SOUNDINGS ONCE AGAIN
INDICATING SOME STEEP LOW AND MID LEVEL LAPSE RATES ASSOCIATED WITH
THE BROAD CYCLONIC FLOW OVER THE REGION WHICH WILL LEAD TO SOME
GUSTY WEST TO NORTHWEST WINDS LATE THIS MORNING THRU THIS AFTERNOON.
850 MB TEMPS A FEW DEGREES COOLER THAN WHAT WE HAD AROUND OUR AREA
YESTERDAY WHICH SHOULD PRODUCE AFTERNOON HIGHS MOSTLY IN THE MIDDLE
70S.

.LONG TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 312 AM CDT TUE AUG 25 2015

QUIET FORECAST AT LEAST UNTIL THE END OF THE WORK WEEK WITH HIGH
TEMPS SLIGHTLY BELOW NORMAL, BUT SLOWLY WARMING THROUGH THE END OF
THE WEEK AHEAD OF THE NEXT SYSTEM.  OVERNIGHT LOWS ALSO ON THE COOL
SIDE AT LEAST UNTIL THE CLOUDS INCREASE SOMEWHAT AHEAD OF THE NEXT
SYSTEM THURSDAY NIGHT IN THE NORTHWEST.  PRECIP ASSOCIATED WITH THE
UPPER LEVEL WAVE, HOWEVER, NOT ANTICIPATED TO IMPACT CENTRAL
ILLINOIS UNTIL FRIDAY NIGHT/SATURDAY MORNING.  SOME SLIGHT CHANCES
CREEPING INTO NW OF THE ILLINOIS RIVER VALLEY FOR FRIDAY, WITH
CHANCES INCREASING THROUGH THE OVERNIGHT AND INTO SAT MORNING.
UPPER LEVEL DISTURBANCE IS DIFFUSE AND SLOW MOVING IN BOTH THE GFS
AND THE ECMWF.  THE NAM IS STARTING TO COME IN A LITTLE MORE COMPACT
AND QUICKER, SO NOT OVERLY CONFIDENT WITH ANY PARTICULAR SOLUTION.
THE GFS AND ECMWF HAVE BEEN BACK AND FORTH ENOUGH OVER THE LAST
SEVERAL SYNOPTIC RUNS THAT CONSENSUS IS WEAK. ALSO NOT INCLINED TO
LEAVE CHANCE POPS IN THE FORECAST ALL THE WAY THROUGH THE WEEKEND
WITH THAT SLOW OF A SYSTEM.  FOR NOW, WILL KEEP THE CONCENTRATION TO
SATURDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 600 AM CDT TUE AUG 25 2015

VFR CONDITIONS ARE EXPECTED THIS FORECAST PERIOD. A LARGE AREA
OF HIGH PRESSURE OFF TO OUR NORTHWEST WILL SLOWLY BUILD SOUTHEAST
INTO THE REGION OVER THE NEXT 24 HOURS KEEPING THE WEATHER ON
THE QUIET SIDE. ABOUT THE ONLY CONCERN WILL BE WITH ANOTHER
BAND OF VFR CIGS OVER PARTS OF SOUTHEAST MN AND WESTERN WI WHICH
WILL SLIP SOUTHEAST AND AFFECT AT LEAST OUR NORTHERN TAF SITES
LATER THIS MORNING THRU THIS AFTERNOON. CLOUD BASES LOOK TO BE
IN THE 4000 TO 5000 FOOT RANGE BASED ON FORECAST SOUNDINGS FOR
KPIA AND KBMI LATE THIS MORNING INTO THE AFTERNOON HOURS. AT
THIS TIME WILL HOLD ON TO SCATTERED CLOUDS FOR THIS TIME FRAME
BUT MAY NEED TO INCLUDE A TEMPO GROUP FOR OUR NORTHERN TAFS
IF A MORE SOUTHWARD PUSH IS OBSERVED WITH THE CLOUD DECK TO
OUR NORTH.

SURFACE WINDS WILL ONCE AGAIN BECOME GUSTY OUT OF A NORTHWEST
DIRECTION LATER THIS MORNING INTO THIS AFTERNOON. PREVAILING WIND
SPEEDS WILL AVERAGE FROM 10 TO 15 KTS WITH A FEW GUSTS UP TO 20
KTS AT TIMES THRU THIS AFTERNOON BEFORE QUICKLY DIMINISHING BY
00Z.

&&

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

$$

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



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