Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 281800
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
100 PM CDT SUN JUN 28 2015

.UPDATE...
ISSUED AT 1045 AM CDT SUN JUN 28 2015

UPDATED THE FORECAST TO INCREASE CHANCES OF SHOWERS AND
THUNDERSTORMS TODAY ESPECIALLY OVER WESTERN AREAS FROM MCS
TRACKING SOUTHEAST. REST OF FORECAST LOOKS ON TRACK WITH HIGHS IN
THE UPPER 70S AND LOWER 80S WITH COOLEST READINGS NW OF IL RIVER
WHERE MORE RAIN/CLOUDS. SPC HAS SLIGHT RISK OF SEVERE STORMS WEST
OF A PIA TO SPI LINE THIS AFTERNOON/EVENING FOR DAMAGING WINDS AND
LARGE HAIL (15% RISK) AND 5% RISK OF TORNADOES AS MORE STORMS
REDEVELOP LATER THIS AFTERNOON AND EARLY EVENING AS AIRMASS
DESTABILIZES.

&&

.SHORT TERM...(TODAY)
ISSUED AT 357 AM CDT SUN JUN 28 2015

ONGOING CONVECTION ACROSS NORTH IOWA WILL SLOWLY MOVE INTO WESTERN
AND NORTHWESTERN IL THIS MORNING, BUT WILL BE DIMINISHING AS IT
MOVES INTO THE AREA. SCATTERED CONVECTION WILL REMAIN POSSIBLE THIS
MORNING SO WILL KEEP CHC POPS IN THE FORECAST, MAINLY WEST OF I-55.
MODERATELY STRONG WEATHER SYSTEM WILL THEN DROP INTO EASTERN IA BY
AFTERNOON WITH A TRAILING COLD FRONT EXTENDING INTO NORTHERN AND
WESTERN MO. HIRES/SHORT RANGE MODELS DEVELOP CONVECTION ALONG AND
AHEAD OF THE SYSTEM IN WESTERN HALF OF IL AND EASTERN MO. MODERATE
INSTABILITY WILL BE AHEAD OF THIS SYSTEM WITH SUFFICIENT BULK SHEAR
AND 0-3KM HELICITY TO PRODUCE SUPERCELLS IN NORTHWESTERN/WESTERN IL
AND NORTHEASTERN MO. STORMS ARE EXPECTED TO MOVE SOUTHEAST EFFECTING
THE CWA DURING THE AFTERNOON. AGREE WITH SPC OUTLOOK OF SLIGHT RISK
OVER WESTERN PART OF THE CWA WHERE THERE WILL BE A SLIGHT OVERLAP OF
BEST INSTABILITY AND BEST SHEAR/HELICITY EXISTS. HOWEVER...WOULD NOT
BE SUPRISED IF SLIGHT AREA GETS EXPANDED EASTWARD SOME LATER THIS
MORNING OR AFTERNOON. SO WILL HAVE LIKELY POPS IN THE WEST FOR THE
CONVECTION. WINDS WILL BE LIGHT AHEAD OF THE SYSTEM OUT OF THE
SOUTHWEST. AFTER HIGHS SHOULD BE SLIGHTLY WARMER THAN YESTERDAY AS
850MB TEMPS WILL BE AROUND 14C.

.LONG TERM...(TONIGHT THROUGH SATURDAY)
ISSUED AT 357 AM CDT SUN JUN 28 2015

A LITTLE WARMER THIS EVENING AS WINDS GET A SOUTHERLY COMPONENT IN
ADDITION TO PERSISTENT CLOUD COVER WITH THE PRECIP TRAPPING THE
TEMPS OVERNIGHT. VIGOROUS SHORT WAVE MOVING INTO THE MIDWEST WITH A
DEVELOPING SFC LOW COLLIDING WITH LIMITED BUT SLIGHTLY INCREASING
MOISTURE IN THE BOUNDARY LAYER AS SOUTHERLY WINDS PUSH RICHER
INSTABILITY INTO THE MIDWEST. BETTER SHEAR IS TO THE WEST/SW WITH
THE DEVELOPMENT OF ROTATING STORMS, AND TIMING OF MAX HEATING WILL
DEF PLAY A ROLE IN THE EVOLUTION FOR THE EVENING.  AS IT STANDS,
WEST CENTRAL IL AND SOUTHWEST INTO MO IN A SLIGHT RISK FOR THE
OVERNIGHT HOURS WITH THE REMAINDER OF CENTRAL IL IN A MARGINAL RISK
TO SEE THE REMAINS OF THE MORE ORGANIZED STORMS THROUGH THE
REMAINDER OF THE NIGHT BRINGING THE THREAT FOR WIND AND HAIL.

NORTHWESTERLY FLOW INTO THE REGION FROM THE PAC NW MAINTAINING A
STEADY STREAM OF SHORT WAVES FOR THE FORECAST. SOME TIMING ISSUES
REMAIN FROM RUN TO RUN, BUT IN GENERAL, AGREEMENT FOR PRECIP TONIGHT
AND INTO TOMORROW...AGAIN ON TUESDAY...AND WED AFTERNOON.  AT THAT
POINT IN THE FORECAST, THE SERIES OF WAVES STARTS TO HAVE A LITTLE
MORE DISSONANCE FROM MODEL TO MODEL.  OVERALL THE FORECAST REMAINS
WET AND STORMY WITH TEMPS SLIGHTLY BELOW NORMAL WITH NORTHWESTERLY
FLOW.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1259 PM CDT SUN JUN 28 2015

A WEAKENING MCS OVER SE IA AND WEST CENTRAL IL IS TRACKING ESE
INTO CENTRAL IL EARLY THIS AFTERNOON WITH SHOWERS AND ISOLATED
THUNDERSTORMS RECENTLY MOVING THROUGH SPI. DEC WILL GET SKIRTED BY
THIS CONVECTION IN NEXT HOUR WITH BRIEF PERIOD OF MVFR
VSBYS/CEILINGS POSSIBLE IN HEAVIER RAINS. MEANWHILE BE MORE
WIDELY SCATTERED INTO MID AFTERNOON ALONG I-74 (PIA...BMI AND
CMI). MORE THUNDERSTORMS ARE EXPECTED TO DEVELOP DURING THIS
AFTERNOON OVER EASTERN IA AND NE MO AHEAD OF 1007 MB SURFACE LOW
OVER CENTRAL IL AND TRACK SE INTO WEST CENTRAL IL LATER THIS
AFTERNOON AND INTO CENTRAL IL DURING THIS EVENING. THIS WILL
BRING CHANCES OF MVFR VSBYS/CEILINGS IN HEAVIER RAINS TO CENTRAL
IL THOUGH MOST OF THE TIME WILL STILL HAVE VFR CONDITIONS. MODELS
SHOW QPF PASSING SHIFTING EAST OF CENTRAL IL BETWEEN 03-07Z FROM
WEST TO EAST. MODELS ALSO SHOW LOW CLOUDS AND REDUCED VSBYS
OVERNIGHT INTO MON MORNING...WITH IFR TO MVFR CONDITIONS AND
GRADUALLY IMPROVING AFTER 15Z/MON. SW WINDS AROUND 10 KTS THIS
AFTERNOON TO VEER NNW 5-9 KTS OVERNIGHT INTO MONDAY MORNING AS LOW
PRESSURE PASSES EAST OF IL INTO CENTRAL INDIANA MONDAY MORNING.

&&

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

&&

$$

UPDATE...07
SHORT TERM...AUTEN
LONG TERM...HJS
AVIATION...07


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