Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 262000
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
300 PM CDT TUE MAY 26 2015

.SHORT TERM...(TONIGHT)
ISSUED AT 300 PM CDT TUE MAY 26 2015

2 PM SURFACE MAP SHOWED LOW PRESSURE CENTERED JUST NORTHWEST OF
DUBUQUE. INITIAL BAND OF CONVECTIVE SHOWERS/ISOLATED THUNDERSTORMS
WHICH MOVED THROUGH THE FORECAST AREA EARLIER HAS ADVANCED NORTHEAST
ACROSS THE INDIANA BORDER...WITH A SECONDARY AXIS OF LIGHT SHOWERS
MOVING EAST AHEAD OF AN UPPER DISTURBANCE CROSSING THE MISSISSIPPI
RIVER.

HRRR AND OTHER HIGH-RESOLUTION MODEL GUIDANCE HAS BEEN DOING A
REASONABLE JOB WITH THE ACTIVITY TODAY...AND WAS GENERALLY FOLLOWED
FOR THE RAIN TRENDS TONIGHT. HAVE MADE SOME ADJUSTMENTS WITH GOING
MAINLY ISOLATED SHOWERS/STORMS THIS EVENING EXCEPT WEST OF I-55...
WHERE LOW CHANCE POP`S WERE KEPT AS A WAVE/TROUGH ADVANCES EAST
ACROSS NORTHERN MISSOURI. HAVE LINGERED THESE 30% CHANCES OVERNIGHT
FROM ABOUT DECATUR WESTWARD. SHOULD SEE SKIES BECOME PARTLY CLOUDY
ACROSS THE SOUTHERN CWA THIS EVENING...BEFORE SOME INCREASE IS NOTED
AGAIN AHEAD OF THE INCOMING WAVE.

&&

.LONG TERM...(WEDNESDAY THROUGH TUESDAY)
ISSUED AT 300 PM CDT TUE MAY 26 2015

AN UNSETTLED WEATHER PATTERN LOOKS TO CONTINUE THROUGH MONDAY ACROSS
CENTRAL AND SOUTHEAST IL ALONG WITH WARM AND RATHER HUMID SUMMERLIKE
CONDITIONS THE REST OF THE WEEK. A COLD FRONT MOVING SE THROUGH
CENTRAL AND SOUTHEAST IL DURING SATURDAY WILL BRING COOLER
TEMPERATURES DURING THIS WEEKEND ESPECIALLY ON SUNDAY.

UPPER LEVEL TROF OVER THE UPPER MIDWEST MOVES INTO MI ON WED WHILE
PUSHING A WEAK FRONT SE INTO THE IL RIVER VALLEY WED AFTERNOON. ALSO
HAVE A SHORT WAVE EJECTING NE FROM THE SOUTHERN PLAINS INTO SE IL
AND CENTRAL INDIANA BY 18Z/WED. INCREASE INSTABLITY ON WED WITH
CAPES OF 1000-2000 J/KG AND HIGHEST SOUTH OF I-72 TO RETURN CHANCES
OF SHOWERS AND THUNDERSTORMS WITH LOWER CHANCES NW OF IL RIVER AND
HIGHER CHANCES IN SOUTHEAST IL. SPC HAS MARGINAL RISK OF SEVERE WED
AFTERNOON SE OF A SHELYVILLE TO PARIS LINE. CONVECTION CHANCES WILL
LINGER SOUTH OF I-72 WED NIGHT MAINLY WED EVENING. THEN ISOLATED
CHANCES OF CONVECTION SHIFT INTO SOUTHERN AND SW AREAS ON THU AS
WEAK HIGH PRESSURE DRIFTS ACROSS THE GREAT LAKES AND MORE STABLE AIR
OVER NE CWA FROM I-74 NE WHERE IT SHOULD BE DRY. NAM MODEL IS STILL
RATHER UNSTABLE THU SW OF I-74 BUT THINK IT MAY BE OVERDOING THIS AS
STRONGER INSTABLITY CLOSER MO AND THE OHIO RIVER VALLEY ON THU PLUS
HAVE UPPER LEVEL RIDGE BUILDING OVER THE EASTERN STATES THU.

WARM FRONT LIFTS NORTH ACROSS CENTRAL IL THU NIGHT AND IN BREEZY SSW
FLOW ON FRIDAY WITH CHANCES OF SHOWERS AND THUNDERSTORM HIGHEST OVER
IL RIVER VALLEY (LIKELY CHANCES WEST OF IL RIVER ON FRIDAY) AND
LOWEST NEAR WABASH RIVER. WARM HIGHS IN THE LOWER 80S WED AND MID
80S THU AND FRI AND A FEW AREAS COULD REACH UPPER 80S WITH ENOUGH
SUNSHINE ESPECIALLY NEAR WABASH RIVER WHERE RAIN CHANCES ARE LOWER.

HAVE LIKELY CHANCES OF SHOWERS AND THUNDERSTORMS FRI NIGHT AND SAT
WITH COLD FRONT PUSHING SE THROUGH CENTRAL IL DURING SATURDAY. HIGHS
SAT TO CONTRAST FROM LOWER 70S NW OF IL RIVER TO LOW 80S IN
SOUTHEAST IL. CONTINUE LIKELY CHANCES OF SHOWERS AND THUNDERSTORMS
SAT NIGHT IN SOUTHEAST IL ESPECIALLY SAT EVENING WHILE LOWERED POPS
TO LOW CHANCE NW OVER IL RIVER VALLEY BEHIND COLD FRONT. AREAS NW OF
IL RIVER NOW APPEAR DRY ON SUNDAY WHILE CHANCE OF SHOWERS AND
THUNDERSTORMS LINGERS FROM I-72 SOUTH CLOSER TO FRONTAL BOUNDARY
PUSHING SE OF OHIO RIVER OVER KY/TN. SUNDAY APPEARS TO BE COOLEST
DAY WITH HIGHS IN UPPER 60S CENTRAL IL AND LOWER 70S SE IL.

EXTENDED MODELS LIKE GFS AND ECMWF CONTINUE TO SHOW A WEAK CUTOFF
UPPER LEVEL LOW EJECTING INTO MO BY MON AND TO CONTINUE CHANCES OF
SHOWERS AND ISOLATED THUNDERSTORMS MONDAY AND TUESDAY. HIGHS IN THE
LOW TO MID 70S MONDAY AND MID TO UPPER 70S TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1240 PM CDT TUE MAY 26 2015

PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS CAN BE EXPECTED AT
TIMES THE NEXT 12-15 HOURS, BETWEEN 18Z AND 08Z, ACROSS CENTRAL
AND EASTERN IL.

THE LATEST HRRR REFLECTIVITY FORECAST HAD A PRETTY GOOD HANDLE ON
THE LOW TOPPED CONVECTION THAT HAS FIRED UP IN THE MS RIVER VALLEY
AROUND THE NOON HOUR. THIS IS EXPECTED TO MOVE INTO CENTRAL IL
FROM 19-21Z AND THEN EASTERN IL FROM 21-23Z. GENERALLY VFR
CONDITIONS ARE ANTICIPATED, BUT WOULD ANTICIPATE MVFR FOR A VERY
SHORT PERIOD OF TIME DURING ANY HEAVY DOWNPOURS.

AFTER A BRIEF BREAK IN CONVECTION EARLY THIS EVENING, THE MAIN
COLD FRONT IS EXPECTED TO MOVE TOWARD CENTRAL IL JUST AFTER
SUNSET. THIS WILL RESULT IN MORE SCATTERED SHOWERS. DECIDED NOT TO
INCLUDE ANY MENTION OF THUNDER AT THIS POINT SINCE INSTABILITY IS
EXPECTED TO BE QUITE LIMITED. AFTER THE FRONTAL PASSAGE THE WIND
IS EXPECTED TO GRADUALLY SHIFT FROM SW TO WSW. THIS WILL ALSO BE
ACCOMPANIED BY VFR CEILINGS/STRATOCUMULUS CLOUDS WRAPPING AROUND
THE LOW LEVEL CYCLONIC FLOW THROUGH MUCH OF WEDNESDAY MORNING.


&&

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

$$

SHORT TERM...GEELHART
LONG TERM...07
AVIATION...MILLER


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