Area Forecast Discussion
Issued by NWS Central Illinois

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000
FXUS63 KILX 280546
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1246 AM CDT TUE JUL 28 2015

.UPDATE...
ISSUED AT 728 PM CDT MON JUL 27 2015

LINE OF THUNDERSTORMS THAT DEVELOPED ALONG A STATIONARY FRONTAL
BOUNDARY LATE THIS AFTERNOON CONTINUES TO PUSH EASTWARD INTO
WEST-CENTRAL ILLINOIS EARLY THIS EVENING. 00Z/7PM RADAR IMAGERY
SHOWS THE LEADING EDGE OF THE PRECIP EXTENDING FROM BURLINGTON,
IOWA TO JUST NORTH OF SAINT LOUIS. THE STORMS ARE MOVING AWAY FROM
THE BEST INSTABILITY AND AS THE SUN SETS, WEAKER INSTABILITY
FURTHER EAST INTO ILLINOIS WILL WANE AS WELL. AS A RESULT, AM
EXPECTING THE CONVECTION TO WEAKEN AND COMPLETELY DISSIPATE BEFORE
MIDNIGHT. BASED ON CURRENT RADAR TRENDS, HAVE INCREASED POPS TO
LIKELY ACROSS THE W/SW CWA THIS EVENING...TAPERING DOWN TO CHANCE
POPS ALONG THE I-55 CORRIDOR. FURTHER EAST, AM EXPECTING DRY
CONDITIONS ACROSS THE REMAINDER OF THE AREA. ONCE THE STORMS FADE,
DENSE CIRRUS CLOUDS WILL LIKELY LINGER FOR MUCH OF THE NIGHT. THIS
WILL TEND TO LIMIT THE POTENTIAL FOR DENSE FOG OVERNIGHT. WILL
STILL KEEP PATCHY FOG IN THE FORECAST THOUGH, AS AIRMASS REMAINS
QUITE MOIST AND WINDS WILL BECOME LIGHT/VARIABLE IN THE VICINITY
OF THE FRONT.

&&

.SHORT TERM...(TONIGHT)
ISSUED AT 255 PM CDT MON JUL 27 2015

REMNANTS OF STATIONARY BOUNDARY DRAPED ACROSS THE MIDWEST THIS
AFTERNOON.  AN UPPER RIDGE BUILDING IN FROM THE WESTERN GULF COAST
UP THROUGH THE UPPER MIDWEST AND WESTERN WI.  LAST NIGHTS FOG
MANAGED TO KEEP A LOT OF MOISTURE IN THE BOUNDARY LAYER THIS
MORNING, ONLY ELEVATING IT TO 2K-3K FT WITH THE CLOUD DECK THIS
AFTERNOON.  WITH CU REDEVELOPING IN ANY GAPS IN THE CLOUD COVER,
MOST AREAS HAVE BEEN MOSTLY CLOUDY THROUGHOUT THE DAY, LIMITING THE
AMOUNT OF DIURNAL MIXING OUT OF THE LLVL DEWPOINTS.  RICH MOISTURE
AND DEWPOINTS IN THE LOW TO MID 70S THIS AFTERNOON WILL LEND ITSELF
TO ANOTHER MUGGY AND WARM EVENING.  PATCHY FOG POSSIBLE LATER
TONIGHT TOWARDS MORNING AS WELL.  MAY NEED TO UPGRADE MENTION TO
DENSE FOG...BUT WILL KNOW BETTER ONCE THE XOVER TEMPS ARE
ESTABLISHED.

.LONG TERM...(TUESDAY THROUGH MONDAY)
ISSUED AT 255 PM CDT MON JUL 27 2015

WEAK CONVERGENT BOUNDARY WILL STILL BE LOCATED IN SOUTHWEST PART OF
CWA TUESDAY SO WILL KEEP A SLIGHT CHANCE OF PCPN IN THE AFTERNOON
ALONG THAT AN JUST AHEAD OF THE APPROACHING COLD FRONT IN THE
NORTHWEST. MODELS VERY SIMILAR WITH THE FRONTAL BOUNDARY AND HAVE
TRENDED QUICKER WITH THE FRONT. SO HAVE CHANCE POPS SOONER FOR TUE
EVENING WITH CONTINUED CHANCE POPS FOR WEDNESDAY. WITH FRONT COMING
THROUGH SOONER...PCPN WILL END SOONER SO HAVE NO POPS FOR WED NIGHT.
DRY WEATHER WILL MOVE INTO THE AREA FOR WED NIGHT THROUGH THE END OF
THE WEEK AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST. THIS
HIGH PRESSURE WILL ALSO BRING LOWER/DRIER DWPTS INTO THE AREA WITH
WESTERLY WINDS. AS THE RIDGES SHIFTS EAST...ANOTHER FRONTAL SYSTEM
WILL PUSH TOWARD THE AREA FOR THE WEEKEND. THIS FRONT IS FORECAST TO
BE SLOW MOVING AND ELOGATED FROM WEST TO EAST...ALMOST PARALLEL WITH
THE FLOW. SO THINK BEST CHANCE OF PCPN WILL BE SUN AND SUNDAY NIGHT.
SO WILL HAVE CHANCE POPS FOR TIME PERIOD.

WITH SOUTHERLY FLOW AHEAD OF AN APPROACHING FRONT...EXPECTING TEMPS
TO GET QUITE WARM TOMORROW...LOOKING AT UPPER 80S IN THE NORTHEAST
TO LOWER 90S IN THE WEST AND SOUTHWEST. THE ONLY POSSIBLE NEGATIVE
TO TEMPS GETTING THIS WARM WILL BE IF THERE IS ANY SCATTERED
CONVECTION OF CONVECTIVE BLOW-OFF CLOUDS OVER THE AREA. DEWPOINTS
ARE IN THE LOWER TO MIDDLE 70S TODAY AND UPPER 70S ARE NOT THAT
FAR AWAY AND SHOULD BE IN THE AREA TOMORROW. SO HOT TEMPS COMBINED
WITH UPPER 70S DWPTS WILL RESULT IN HEAT INDEX VALUES OF 100 IN
THE EAST TO 110 IN THE WEST. SO WILL BE ISSUING A HEAT ADVISORY
FOR MOST OF THE AREA...TO NOT INCLUDE 4 COUNTIES IN THE EAST. WITH
THE FRONT COMING THROUGH SOONER ON WEDNESDAY...TEMPS AND DEWPOINTS
IN THE SOUTHWEST WILL NOT GET HIGH ENOUGH TO WARRANT A
CONTINUATION OF THE ADVISOR THROUGH WED. BEYOND THE FRONT ON
WED...TEMPS WILL DROP BACK DOWN INTO THE 80S WITH DEWPOINTS BACK
INTO THE 60S.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1246 AM CDT TUE JUL 28 2015

DENSE CIRRUS SHIELD LEFT BEHIND BY CONVECTION THAT DISSIPATED
THIS EVENING CONTINUES TO BLANKET CENTRAL ILLINOIS EARLY THIS
MORNING...HOWEVER IT IS BEGINNING TO CLEAR OUT NORTHWEST OF THE
ILLINOIS RIVER. MAIN SHORT-TERM AVIATION CONCERN WILL BE HOW
MUCH FOG WILL FORM BETWEEN NOW AND DAWN. WITH SKIES CLEARING FROM
WEST TO EAST AND CONTINUED VERY LIGHT E/NE WINDS...FOG WILL
DEVELOP EVERYWHERE. THINK IT WILL BE THICKEST WHERE LIGHT RAIN
OCCURRED LAST EVENING AND WHERE SKIES CLEAR EARLIEST. AS A
RESULT...HAVE HIT VISBY RESTRICTIONS HARDEST AT BOTH KPIA AND
KSPI AFTER 08Z/09Z. MODELS SUGGEST WIDELY SCATTERED CONVECTION MAY
DEVELOP ALONG THE STATIONARY FRONTAL BOUNDARY NEAR THE MISSISSIPPI
RIVER THIS MORNING. WHILE CONFIDENCE REMAINS LOW...HAVE OPTED TO
INCLUDE VCTS AT KSPI BETWEEN 12Z AND 17Z. AFTER THAT...MAINLY DRY
CONDITIONS ARE ANTICIPATED THROUGHOUT THE DAY BEFORE A COLD FRONT
APPROACHES BY MID TO LATE EVENING. HAVE INTRODUCED VCTS AT KPIA
AFTER 03Z...ALTHOUGH THE BEST FOCUS FOR THUNDER WILL LIKELY HOLD
OFF UNTIL AFTER 06Z.

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM CDT THIS EVENING
FOR ILZ027>031-036>038-040>044-047>054-056-061>063-066>068-
071>073.

&&

$$

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


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