Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 262304
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
604 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 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)
ISSUED AT 600 PM CDT TUE MAY 26 2015

MAIN FORECAST CONCERN WILL BE ANY ADDITIONAL SHOWER ACTIVITY AND
AFFECT ON CLOUD BASES LATER THIS EVENING...AND THE POTENTIAL FOR
SOME MVFR FOG TOWARDS DAWN WED. LATEST SURFACE MAP HAS A WEAK
BOUNDARY/WIND SHIFT LINE OVER CENTRAL IOWA EARLY THIS EVENING
AND THAT FEATURE IS EXPECTED TO SLOWLY PUSH ACROSS THE FORECAST
AREA LATE TONIGHT/WED MORNING. NOT MUCH OF A TEMP OR DEW POINT
DISCONTINUITY ASSOCIATED WITH THE FEATURE AND THE UPPER LEVEL
LIFT IS MEAGER SO NOT EXPECTING MUCH IN THE WAY OF WIDESPREAD
RAINFALL OVERNIGHT AS IT PUSHES THROUGH THE AREA. FORECAST
SOUNDINGS SUGGEST SOME LOW MVFR CIGS AT TIMES AHEAD OF THE
FRONT WITH THE WIND FIELDS QUITE LIGHT ALONG AND JUST BEHIND
THE FRONT WHICH MAY ALLOW SOME MVFR FOG TO FORM TOWARDS WED
MORNING. CURRENT FORECAST SOUNDINGS INDICATE ENOUGH CLOUD
COVER WILL LINGER OVERNIGHT...ESPECIALLY IN THE MID AND UPPER
PORTIONS OF THE ATMOSPHERE THAT MAY LIMIT ANY RESTRICTIONS TO
VSBYS. FOR NOW WILL INTRODUCE A 5 TO 6 MI VSBY AT BMI AND CMI
WHICH WILL BE SEEING THE LIGHTER WINDS OVERNIGHT.

AN UPPER LEVEL WAVE IS FORECAST TO PUSH ACROSS THE SOUTHERN PLAINS
TONIGHT AND EDGE ENE INTO PARTS OF SOUTH CENTRAL IL BY MORNING
WED BRINGING SOME SCATTERED SHOWERS AND THUNDERSTORMS WITH IT.
CURRENT GUIDANCE SUGGESTS THE BULK OF THE RAIN SHOULD REMAIN SOUTH
OF THE TAF SITES WITH MAINLY VFR CONDITIONS EXPECTED FOR THE
REMAINDER OF THE DAY. SOUTHWEST WINDS AROUND 10KTS EXPECTED
TONIGHT WILL VEER MORE INTO A WESTERLY DIRECTION AS THE WEAKENING
BOUNDARY SHIFTS ACROSS THE AREA DURING THE DAY WEDNESDAY. WIND
SPEEDS SHOULD RANGE FROM 10 TO 15 KTS.

&&

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

$$

SHORT TERM...GEELHART
LONG TERM...07
AVIATION...SMITH



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