Area Forecast Discussion
Issued by NWS Central Illinois

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580
FXUS63 KILX 180200
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
900 PM CDT SUN MAY 17 2015

.UPDATE...
ISSUED AT 852 PM CDT SUN MAY 17 2015
OVERNIGHT FORECAST DOING WELL. SOUTHERLY WINDS MAINTAINING SOME
WARM TEMPS FOR THE OVERNIGHT...AND MAJORITY OF PRECIP THREAT ALONG
AND SOUTH OF A LINE FROM TAYLORVILLE TO CHAMPAIGN. SHORT TERM
MODELS PREV BLEW SOME CONVECTION INTO SOUTHEASTERN IL WORKING OFF
OF OUTFLOW FROM ACTIVITY IN MO. HOWEVER, ATMOSPHERE HAVING
DIFFICULT TIME FOCUSING ANY LIFT, PARTICULARLY WITH THE LOSS OF
THE DIURNAL COMPONENT TO THE INSTABILITY. SHOWERS SO FAR HAVE
REMAINED LIMITED AND THE BULK OF THE THUNDER FURTHER TO THE SOUTH.
ISO TS POSSIBLE IN THE FAR SE...BUT NOT WIDESPREAD. NOT MUCH IN
THE WAY OF UPDATES ANTICIPATED AT THIS TIME.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 256 PM CDT SUN MAY 17 2015

POTENTIAL FOR SEVERE WEATHER THIS AFTERNOON/EVENING IS STILL BEING
MONITORED...HOWEVER IT IS BEGINNING TO LOOK LIKE ANY SEVERE WILL BE
ISOLATED AT BEST.  18Z KILX UPPER AIR SOUNDING SHOWS SBCAPE OF
2000J/KG AND 0-6KM BULK SHEAR OF 35KT: HOWEVER, A WARM LAYER AT
AROUND 900MB IS KEEPING THE ATMOSPHERE MOSTLY CAPPED.  REGIONAL
MESOSCALE ANALYSIS INDICATES A POCKET OF GREATER INSTABILITY ACROSS
NORTH-CENTRAL ILLINOIS FROM PEORIA/BLOOMINGTON NORTHWARD...MAKING
THIS THE PRIMARY SPOT FOR POTENTIAL CONVECTIVE DEVELOPMENT OVER THE
NEXT COUPLE OF HOURS.  HRRR SHOWS THIS SCENARIO UNFOLDING...WITH
SCATTERED STORMS LIFTING NORTHWARD INTO NORTHERN ILLINOIS/SOUTHERN
WISCONSIN LATER THIS AFTERNOON.  FURTHER SOUTH...THE UPSTREAM
AIRMASS ACROSS MISSOURI/SOUTHWEST ILLINOIS REMAINS STABLE AND CAPPED
IN THE WAKE OF A MORNING OUTFLOW BOUNDARY THAT HAS PUSHED WELL TO
THE EAST INTO WESTERN SECTIONS OF KENTUCKY AND TENNESSEE.  END
RESULT WILL LIKELY BE ONLY WIDELY SCATTERED STORMS DEVELOPING ALONG
THE I-55 CORRIDOR AFTER 21Z...WITH MINIMAL SEVERE WEATHER THREAT.
HIGH-RES MODELS CONTINUE TO SUGGEST CONVECTION WILL RE-DEVELOP OVER
SOUTHEAST MISSOURI/ARKANSAS THIS EVENING...THEN LIFT INTO SOUTHEAST
ILLINOIS TONIGHT.  PARTIAL CLEARING HAS OCCURRED ACROSS THIS
AREA...HOWEVER AIRMASS REMAINS STABLE BEHIND THE PREVIOUS OUTFLOW
BOUNDARY...SO AM SKEPTICAL OF THIS SOLUTION.  WILL CONTINUE TO
MONITOR SOUTHEAST MISSOURI FOR DEVELOPMENT OVER THE NEXT SEVERAL
HOURS.  AT THIS TIME...WILL CARRY ONLY SLIGHT OR LOW CHANCE POPS
WEST OF THE I-57 CORRIDOR THROUGH THE EVENING HOURS...WITH DRY
CONDITIONS OVERNIGHT.  FURTHER EAST...WILL GO WITH HIGHER POPS IN
THE HIGHER DEWPOINT/MORE UNSTABLE AIRMASS ALONG/EAST OF I-57.

.LONG TERM...(MONDAY THROUGH SUNDAY)
ISSUED AT 256 PM CDT SUN MAY 17 2015

COLD FRONT WILL PASS THROUGH CENTRAL ILLINOIS ON MONDAY...DROPPING
SOUTH OF THE I-70 CORRIDOR BY LATE AFTERNOON.  SCATTERED SHOWERS AND
THUNDERSTORMS MAY DEVELOP AHEAD OF THE FRONT...HOWEVER AREAL
COVERAGE WILL BE GREATEST FURTHER EAST ACROSS THE OHIO RIVER VALLEY.
WILL MAINTAIN CHANCE POPS ALONG/EAST OF A DANVILLE TO SHELBYVILLE
LINE THROUGHOUT THE DAY UNTIL THE BOUNDARY EXITS.  HIGH PRESSURE
WILL TAKE CONTROL OF THE WEATHER BEHIND THE DEPARTING
FRONT...PROVIDING COOL/DRY WEATHER FOR TUESDAY.  RESULTING HIGH
TEMPERATURES WILL REMAIN IN THE LOWER TO MIDDLE 60S...WHILE
OVERNIGHT LOWS DIP INTO THE 40S.

PIECE OF ENERGY IS EXPECTED TO EJECT FROM WESTERN CONUS UPPER LOW BY
MID-WEEK...BRINGING CLOUDS AND PERHAPS A FEW SHOWERS INTO THE AREA
ON WEDNESDAY.  MODELS DEPICT A WEAKENING WAVE COMING INTO A VERY DRY
AIRMASS...SO THINK ANY RAINFALL WILL BE QUITE LIGHT.  HAVE CUT BACK
ON POPS...FEATURING LIKELY ACROSS THE FAR SOUTHWEST CWA AROUND
JACKSONVILLE TAPERING DOWN TO JUST SLIGHT ALONG THE INDIANA BORDER.
ONCE THIS WAVE DEPARTS...COOL/DRY WEATHER WILL RETURN FOR THURSDAY
AND FRIDAY.

MAIN UPPER LOW WILL GRADUALLY LIFT INTO THE PLAINS LATE IN THE
PERIOD...BRINGING THE NEXT SIGNIFICANT CHANCE FOR RAIN BY LATE IN
THE WEEKEND.  WHILE MODEL DIFFERENCES STILL EXIST...GFS/ECMWF
CONSENSUS POINTS TO THE SUNDAY/MONDAY TIME FRAME AS THE PRIMARY TIME
FOR SHOWERS AND THUNDERSTORMS.  HAVE THEREFORE KEPT RAIN CHANCES OUT
OF THE FORECAST FOR SATURDAY...THEN HAVE HIT POPS HARD FOR SUNDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 636 PM CDT SUN MAY 17 2015
MODELS INCONSISTENT AND NOT DOING WELL WITH TIMING OR DEVELOPMENT
OF CONVECTION AND CONSIDERING THE LACK OF ACTIVITY OUT TO THE WEST
THIS AFTERNOON...KEEPING EVEN MENTION OUT. MAY NEED TO CONSIDER
ADDING VCTS TO DEC OR CMI IN THE OVERNIGHT DEPENDING ON TRACK OF
WEAK CONVECTION TO THE SOUTHWEST...BUT SO FAR...NOT A MAJOR
THREAT. GUSTS EXPECTED TO SLACK OFF AS SUN SETS...WINDS BECOMING
MORE WESTERLY BY TOMORROW AND SOME SCT CU ALONG AND SOUTHEAST OR A
BMI TO SPI LINE FOR THE MOST PART, WITH SOME CIRRUS. SO FAR, A VFR
FORECAST THROUGH 24 HRS.


&&

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

$$

UPDATE...HJS
SHORT TERM...BARNES
LONG TERM...BARNES
AVIATION...HJS



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