Area Forecast Discussion
Issued by NWS Central Illinois

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FXUS63 KILX 031759
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1259 PM CDT FRI JUL 3 2015

.UPDATE...
ISSUED AT 1045 AM CDT FRI JUL 3 2015

FORECAST OVERALL LOOKS GOOD TODAY AS VARIABLY CLOUDY SKIES
PREVAIL WITH A FEW SPRINKLES INTO MIDDAY EAST OF THE IL RIVER AND
ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON FROM I-70
SOUTHEAST. HIGHS IN THE UPPER 70S TO NEAR 80F WITH NE WINDS
NEAR 10 MPH OR LESS.

LATE MORNING SURFACE ANALYSIS SHOWS WEAK 1016 MB HIGH PRESSURE
OVER SOUTHERN MI/WI INTO NORTHERN IA. WEAK 1010 MB LOW PRESSURE
OVER NORTHERN KY WITH A FRONTAL BOUNDARY OVER FAR SOUTHERN IL TO
NEAR THE MO/AR BORDER. THIS FRONT HAS PUSHED A BIT FURTHER SOUTH
AS WEAK SURFACE LOW PRESSURE TRACKED EAST AND BEST CHANCES OF
SHOWERS AND THUNDERSTORMS TODAY ALSO HAVE SHIFTED SOUTHWARD. SPC
HAS SHIFTED MARGINAL RISK OF SEVERE STORMS THIS AFTEROON/EARLY
EVENING TO JUST SOUTH OF IL WHILE SLIGHT RISK OVER AR AND SOUTHERN
TN. A WEAK SHORT WAVE OVER CENTRAL IL LATE THIS MORNING WILL TRACK
SE ACROSS EASTERN IL THIS AFTERNOON KEEPING CHANCES OF SPRINKLES
EAST OF IL RIVER WHILE ISOLATED CONVECTION TO APPEAR IN SOUTHEAST
IL THIS AFTERNOON AND INTO MID EVENING UNTIL SUNSET. DEWPOINTS
CURRENTLY RANGE FROM AROUND 60F NORTHERN COUNTIES TO MID TO UPPER
60S IN SOUTHEAST IL FROM I-70 SOUTH. DEWPOINTS ARE RUNNING A
COUPLE DEGREES HIGHER THAN 24 HOURS AGO...SO SLIGHTLY MORE HUMID
TODAY.

&&

.SHORT TERM...(TODAY)
ISSUED AT 331 AM CDT FRI JUL 3 2015

THE 08Z/3AM SURFACE ANALYSIS SHOWS A STATIONARY FRONT EXTENDING WEST-
EAST JUST SOUTH OF ILLINOIS, WITH A SURFACE LOW MOVING EAST ALONG
THE FRONT NEAR EVANSVILLE. A TROUGH OF LOW PRESSURE EXTENDING NORTH
FROM THE LOW WILL BE A FOCUS FOR SHOWERS AND A FEW STORMS TO DEVELOP
DURING THE DAY TODAY, MAINLY SOUTHEAST OF I-70. ALOFT, A SHORTWAVE
OVER IOWA AND INTO WESTERN ILLINOIS IS TRIGGERING SPOTTY SPRINKLES
ACROSS CENTRAL ILLINOIS. MOST OF THE CLOUD BASES WITH THAT FEATURE
ARE AT OR ABOVE 12K FEET, WHICH IS USUALLY HIGH ENOUGH THAT THE RAIN
DOESN`T REACH THE GROUND. HRRR AND RAP OUTPUT WERE NOT HANDLING THAT
WAVE AT ALL EARLIER. THE HRRR FINALLY ACKNOWLEDGED IT LAST HOUR, AND
SHOWS ALL SPRINKLES DISSIPATING IN A COUPLE HOURS. BASED ON
SATELLITE IMAGERY, AND FORECAST MOVEMENT OF THE UPPER TROUGH AXIS
ACROSS ILLINOIS THE REST OF THE DAY, WILL KEEP SPRINKLES IN THE
FORECAST ACROSS OUR NORTHERN AND CENTRAL COUNTIES INTO THE
AFTERNOON.

INSTABILITY PARAMS SHOW A MORE FAVORABLE ENVIRONMENT FOR A FEW
STORMS WILL REMAIN CLOSER TO THE LOW PRESSURE IN OUR SE COUNTIES. NO
STRONG STORMS ARE EXPECTED, AS SEVERE POTENTIAL WILL REMAIN ALONG
THE STATIONARY FRONT WELL SOUTH OF OUR AREA.

CLOUD COVER WILL REMAIN HIGH DUE TO MOISTURE CONTENT AT MULTIPLE
LEVELS. LOW CLOUDS ARE PROJECTED TO AFFECT OUR EASTERN COUNTIES AS
THE WEAK SURFACE TROUGH LINGERS NEAR THE IL-IN BORDER. HIGH CLOUDS
WILL AFFECT THE WESTERN COUNTIES AS THE UPPER SHORTWAVE PASSES
ACROSS IL. THE CLOUDS WILL KEEP HIGHS A FEW DEGREES COOLER, WITH
HIGHS IN THE UPPER 70S. PREVAILING WINDS WILL BE NORTHEAST DUE TO
LOW SURFACE PRESSURE SOUTHEAST OF OUR AREA.

.LONG TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 331 AM CDT FRI JUL 3 2015

NOT MUCH OF A SHIFT OVERALL IN THE FORECAST RUNS THIS TIME
AROUND...SO THE NEXT COUPLE OF DAYS ARE STILL DRY FOR THE MOST PART
IN THE FORECAST.  AS THE FLOW SHIFTS FROM NWRLY TO VERY WEAK AND
DIFFUSE, MODELS ARE ALREADY MISSING SOME WEAK RETURNS THIS MORNING
ON RADAR WITH A WEAK OPEN WAVE ALOFT.  ALTHOUGH THERE WILL REMAIN
THE CONCERN FOR WEAK WAVES PROVIDING SOME LIFT...FORECAST IS DRY
THROUGH THE WEEKEND.  COOLER THAN NORMAL TEMPS FOR SATURDAY WITH
INCREASINGLY CLEARER SKIES...ALTHOUGH SOME HAZE STILL AN ISSUE.
WARMING MID-LEVELS, AMPLE SUNSHINE, AND A WEAK SOUTHERLY
COMPONENT TO THE WINDS ON SUNDAY WILL PUSH THE TEMPS UP A FEW MORE
DEGREES FROM SATURDAY`S HIGHS...CLOSER TO SEASONAL NORMS FOR THE
BEGINNING OF JULY. UPPER TROF DIGS INTO THE NRN PLAINS LATE IN THE
WEEKEND, DRIVING A FRONT THROUGH THE MIDWEST FOR MON NIGHT AND
INTO TUESDAY, WITH THE NEXT BIG CHANCE FOR PRECIP. AND LOWER TEMPS
FOR TUESDAY AND WEDNESDAY IN THE WAKE OF THE BOUNDARY. HOWEVER,
THIS IS WHERE THE FORECAST BECOMES FAMILIAR AGAIN. WITH WEAK
QUASI-ZONAL FLOW ALOFT, THE FRONT LAYS OUT INVOF THE OHIO RIVER
VALLEY AND STARTS TO STALL OUT. HOW FAR SOUTH THE BOUNDARY GETS
WHILE INTERACTING WITH SHORTWAVES RIDING OUT OF THE PLAINS AND
THROUGH THE MID MISS RIVER VALLEY WILL ULTIMATELY END UP
CONTROLLING THE POPS IN THE LONG TERM.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1258 PM CDT FRI JUL 3 2015

SCATTERED TO BROKEN CUMULUS CLOUDS 3-6K FT TO OCCUR THIS
AFTERNOON ALONG WITH SOME BROKEN MID/HIGH CLOUDS ESPECIALLY SE OF
THE IL RIVER/PIA. HAVE VCSH WITH MAINLY SPRINKLES AT DEC AND CMI
INTO MID AFTERNOON OTHERWISE ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS TO BE CONFINED TO AREAS SOUTH OF I-70 CLOSER TO
FRONTAL BOUNDARY IN NORTHERN KY INTO SE MO. WEAK HIGH PRESSURE
1016 MB FROM NEBRASKA TO NORTHERN IA AND CENTRAL LOWER MI TO BUILD
SLOWLY SE INTO THE REGION OVERIGHT AND SAT. NE WINDS OF 5-9 KTS
THIS AFTERNOON TO BECOME LIGHT AND VARIABLE AFTER SUNSET TONIGHT
AND CONTINUE SAT MORNING. HAVE MVFR VSBYS ARRIVING WITH SOME FOG
DEVELOPMENT AFTER 08Z WITH PATCHY IFR VSBYS WITH FOG MAINLY IN
EASTERN IL. ANY FOG THAT DEVELOPS OVERNIGHT WILL LIFT TO LIGHT
HAZE BY 15Z SAT WITH FEW CUMULUS CLOUDS AND SCATTERED CIRRUS.

&&

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

&&

$$

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


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