109 
FXUS63 KILX 131807
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
107 PM CDT SAT JUL 13 2013

.DISCUSSION...
ISSUED 1038 AM CDT SAT JUL 13 2013
NARROW HIGH PRESSURE RIDGE OVER CENTRAL IL WITH UPPER LOW STILL
ANCHORED OVER THE APPALACHIAN MOUNTAINS SE OF THE OHIO RIVER
VALLEY. PERSISTENT CIRRUS SHIELD TO THE NW...THOUGH THE SERN EDGE
IS ERODING SOMEWHAT AS IT RUNS INTO DRIER AIR...CIRRUS STILL IN
PLACE NW OF THE IL RIVER VALLEY AND TEMPERING THE DIURNAL SWING
OVER GALESBURG. FOR THE MOST PART...FORECAST IS DOING
WELL...EXPECT THE RETURN OF CU THIS AFTERNOON...WITH A THREAT FOR
SCT PRECIP/TS IN THE SE. HAVE UPDATED THE HOURLY TEMPS AS THEY ARE
A BIT AHEAD OF THE CURVE SO FAR THIS MORNING. SOME MINOR TWEAKS TO
THE SKY GRIDS AS WELL TO ACCOUNT FOR THE CIRRUS TO THE NW. ZONE
UPDATES OUT MOMENTARILY. 



&&

.AVIATION...
ISSUED 104 PM CDT SAT JUL 13 2013
NOT MUCH OF A SHIFT IN THE FORECAST OVERALL. CU THIS
AFTERNOON...CONCENTRATED IN SOUTH AND EASTERN TERMINALS. VCTS
MENTION FOR DEC...AND NOW CMI...CLOSER TO THE CENTER OF THE UPPER
LEVEL LOW. VFR PREDOMINATE THROUGH THE AFTERNOON...UNTIL TONIGHT.
LIGHT WINDS AND MOSTLY CLEAR SKIES SETTING UP FOR A BIT OF
RADIATIONAL COOLING COULD RESULT IN SOME MVFR VIS DROPS.
TOMORROW... MUCH OF THE SAME WITH LIGHT/VARIABLE E/SERLY WINDS AND
MOSTLY CLEAR SKIES THROUGH THE MORNING. 


HJS
&&

.PREV DISCUSSION...
ISSUED 330 AM CDT SAT JUL 13 2013

SHORT TERM...TODAY THROUGH MONDAY NIGHT

00Z MODELS RETROGRADE 576 DM 500 MB LOW OVER EASTERN KY WESTWARD 
INTO SOUTHERN IL BY SUNSET AND INTO THE OZARKS SUNDAY
MORNING...THEN INTO CENTRAL OK BY SUNSET SUNDAY. BANDS OF MID
LEVEL CLOUDS OVER OHIO...EASTERN KY AND SE INDIANA TO PUSH
WESTWARD INTO EAST CENTRAL AND SE IL LATER THIS MORNING AND THEN
HAVE ISOLATED CONVECTION DEVELOPING DURING THE AFTERNOON FROM I-72
SOUTH WITH 30% CHANCES SE OF I-70 LATER THIS AFTERNOON AND
LINGERING UNTIL SUNSET. SPC HAS 5% RISK OF LARGE HAIL AND DAMAGING
WIND GUSTS GENERALLY FROM I-72 SOUTH FROM MID AFTERNOON INTO EARLY
EVENING WHERE CAPES ELEVATE TO AROUND 1000 J/KG. PER SPC DAY1 OUTLOOK...
IN ASSOCIATION WITH THE RETROGRADING UPPER LOW...A POCKET OF -12
TO -16 DEG C 500 MB TEMPERATURES SHOULD SHIFT WESTWARD FROM TN/MID
MS VALLEY VALLEY DURING THE DIURNAL HEATING CYCLE. ALTHOUGH LOW-
LEVEL FORCING FOR ASCENT APPEARS NEBULOUS...STEEP LOW/MID-LEVEL
LAPSE RATES SHOULD YIELD ISOLATED TO WIDELY SCATTERED CONVECTION.
A FEW STORMS MAY GENERATE SEVERE HAIL AND LOCALIZED STRONG WINDS.
HIGHS THIS AFTERNOON IN THE MID 80S WITH DEWPOINTS IN THE LOW TO
MID 60S. ISOLATED CONVECTION OVER SE IL THIS EVENING UNTIL SUNSET
THEN DRY CONDITIONS EXPECTED REST OF TONIGHT. LOWS IN THE LOW TO
MID 60S. 

DESPITE UPPER LEVEL LOW MOVING FURTHER AWAY FROM CENTRAL IL SUNDAY 
THE INSTABILITY SUNDAY AFTERNOON IS GREATER THAN TODAY SE OF THE
IL RIVER AND SHOULD BE ENOUGH TO DEVELOP ISOLATED CONVECTION AGAIN
SUNDAY AFTERNOON SE OF THE IL RIVER WITH 30% CHANCE POPS OVER SE IL.
THUNDERSTORMS THAT DEVELOP WILL BE SLOW MOVING AND WILL HAVE HEAVY
RAIN AS PRECIPITABLE WATER VALUES ELEVATE CLOSER TO 2 INCHES
SUNDAY AFTERNOON. THIS CONVECTION TO DIMINISH BY SUNSET SUNDAY
EVENING. HIGHS SUNDAY IN THE MID TO UPPER 80S WITH DEWPOINTS 65 TO 70F.

HAVE SLIGHT CHANCE OF CONVECTION ACROSS CENTRAL AND SE IL MONDAY
AFTERNOON UNTIL SUNSET AS UNSTABLE AIRMASS PUSHES FURTHER NW
ACROSS THE IL RIVER VALLEY TOO. HIGHS MONDAY IN THE UPPER 80S WITH
AREAS SE OF I-70 GETTING NEAR 90F. DEWPOINTS OF 70 TO 75F WITH
HEAT INDICES PEAKING FROM MID TO UPPER 90S OVER CENTRAL IL AND
UPPER 90S TO NEAR 100F IN SE IL.

LONG TERM...TUESDAY THROUGH SATURDAY

599 DM 500 MB HIGH PRESSURE RIDGE TO RETROGRADE WESTWARD FROM THE
MID ATLANTIC STATES INTO THE OHIO VALLEY AND IL BY MIDDLE OF NEXT
WEEK. THIS TO BRING HOT AND HUMID WEATHER TO THE REGION THROUGH
FRIDAY WITH HIGHS AROUND 90/LOWER 90S AND AFTERNOON HEAT INDICES
AROUND 100F. CONTINUE SLIGHT CHANCE OF CONVECTION ESPECIALLY
DURING THE AFTERNOON/EARLY EVENING HOURS. BEST CHANCES OF
CONVECTION OVER NORTHERN IL FRI SHIFTS SOUTHWARD WITH A FRONTAL
BOUNDARY FRI NIGHT AND SAT INTO CENTRAL IL. COOLER AND LESS HUMID
WEATHER EXPECTED NEXT WEEKEND WITH PASSAGE OF FRONTAL BOUNDARY. 

07


&&

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

$$