Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 040803
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
303 AM CDT FRI SEP 4 2015

.SHORT TERM...(TODAY)
ISSUED AT 303 AM CDT FRI SEP 4 2015

SPRAWLING UPPER-LEVEL RIDGE EXTENDING FROM THE SOUTHERN PLAINS INTO
THE WESTERN GREAT LAKES WILL CONTINUE TO DOMINATE THE WEATHER ACROSS
CENTRAL ILLINOIS TODAY...LEADING TO MOSTLY SUNNY SKIES WITH HIGH
TEMPERATURES ONCE AGAIN TOPPING OUT IN THE LOWER TO MIDDLE 90S.  THE
ONLY POTENTIAL FLY-IN-THE-OINTMENT WILL BE AN UPPER LOW SPINNING
OVER MICHIGAN.  08Z/3AM WATER VAPOR IMAGERY SHOWS THE MAIN LOW OVER
LAKE HURON...HOWEVER A WELL-DEFINED CIRCULATION IS NOTED ROTATING
AROUND THE LOW ACROSS EASTERN WISCONSIN. MODELS TAKE THIS FEATURE
ON A SOUTHEASTERLY TRAJECTORY ACROSS SOUTHERN LAKE MICHIGAN INTO
FAR NORTHERN INDIANA...WITH MOST OF ITS ASSOCIATED CONVECTION
REMAINING N/NE OF THE KILX CWA. HOWEVER THIS WAVE WILL PASS CLOSE
ENOUGH TO THE AREA TO WARRANT A SLIGHT CHANCE POP ALONG/NORTHEAST
OF A LACON TO PARIS LINE DURING THE AFTERNOON.

&&

.LONG TERM...(TONIGHT THROUGH Thursday)
ISSUED AT 303 AM CDT FRI SEP 4 2015

UPPER LOW WILL REMAIN IN PLACE OVER MICHIGAN THROUGH SATURDAY...WITH
THE GFS DEVELOPING PRECIP WELL TO THE SOUTH INTO PORTIONS OF NORTH-
CENTRAL ILLINOIS.  THINK THIS MAY BE A BIT TOO AGGRESSIVE GIVEN THE
WEAKENING TREND OF THE SYSTEM AND THE FACT THAT BOTH THE NAM AND
ECMWF SHOW DRY CONDITIONS ACROSS THE AREA.  WILL MAINTAIN JUST A
SLIGHT CHANCE POP NORTHEAST OF THE I-74 CORRIDOR...BUT IF CURRENT
TRENDS CONTINUE THIS MAY BE REMOVED BY LATER SHIFTS.  ASIDE FROM
THIS VERY SLIM CHANCE FOR RAIN ACROSS THE FAR NE CWA...HOT AND DRY
WEATHER WILL PREVAIL BOTH SATURDAY AND SUNDAY WITH HIGH TEMPERATURES
REACHING THE LOWER TO MIDDLE 90S.

AFTER THAT...THINGS GET A LITTLE MORE INTERESTING AS MAJOR PATTERN
CHANGE OCCURS NEXT WEEK.  MODELS ARE BEGINNING TO COME INTO BETTER
AGREEMENT CONCERNING THE TIMING OF THIS PROCESS...WITH CONSENSUS
BRINGING THE INITIAL WEAKENING COLD FRONT INTO CENTRAL ILLINOIS ON
MONDAY.  AS IS TYPICALLY THE CASE WITH A PATTERN CHANGE OF THIS
MAGNITUDE...MODELS HAVE BEEN TOO FAST WITH THE FRONT.  AS A
RESULT...HAVE TRIMMED POPS SUNDAY NIGHT TO FEATURE JUST LOW CHANCE
ACROSS THE ILLINOIS RIVER VALLEY LATE.  HAVE ALSO SLOWED THE
EASTWARD PROGRESSION OF PRECIP ON MONDAY...WITH AREAS EAST OF I-57
REMAINING DRY THROUGH THE ENTIRE DAY.  THE FRONTAL BOUNDARY WILL
BECOME PARALLEL TO THE UPPER FLOW AND WILL STALL ACROSS THE
AREA...KEEPING CHANCE POPS IN THE FORECAST MONDAY NIGHT THROUGH
TUESDAY NIGHT.  AS A MORE SIGNIFICANT UPPER WAVE DIVES SOUTHEASTWARD
OUT OF CANADA...IT WILL PUSH A STRONGER COLD FRONT INTO ILLINOIS ON
WEDNESDAY.  GIVEN AMPLE LOW-LEVEL MOISTURE...STRONG UPPER
DYNAMICS...AND ADEQUATE CONVERGENCE ALONG THE BOUNDARY...HAVE OPTED
TO CARRY LIKELY POPS ON WEDNESDAY.  FRONT WILL DROP SOUTHWARD INTO
THE OHIO RIVER VALLEY BY THURSDAY...RESULTING IN COOLER AND DRIER
CONDITIONS WITH HIGH TEMPERATURES DROPPING INTO THE MIDDLE TO UPPER
70S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z Friday NIGHT)
ISSUED AT 1138 PM CDT THU SEP 3 2015

VFR CONDITIONS ACROSS CENTRAL IL THIS EVENING. BY MORNING PATCHY
LIGHT FOG IS POSSIBLE. INCLUDED TEMPO MVFR VSBY DUE TO FOG AT
KPIA/KBMI/KCMI BASED ON PERSISTENCE FROM PREVIOUS NIGHT ALONG
WITH MODEL GUIDANCE. AFTER SUNRISE ANY LIGHT FOG WILL DISSIPATE.
ALTHOUGH CHANCE FOR THUNDERSTORM DEVELOPMENT AFTERNOON-EVENING
FRIDAY IS NON-ZERO...CHANCES ARE TOO LOW FOR VCTS MENTION IN TAFS
AT THIS POINT. MOST LIKELY AREA WOULD BE KBMI-KCMI NORTHEASTWARD.
WINDS S-SW UP TO 8 KTS THROUGH THE PERIOD.


&&

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

$$

SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Onton


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