000
FXUS63 KILX 230830
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
330 AM CDT THU MAY 23 2013

.DISCUSSION...
ISSUED 330 AM CDT THU MAY 23 2013

SHORT TERM...TODAY THROUGH FRIDAY NIGHT

560 DM 500 MB LOW NEAR THE IA/WI/IL BORDER AND ASSOCIATED UPPER
LEVEL TROF TO PULL EASTWARD ACROSS IL THIS MORNING AND OVER IN/OH
THIS AFTERNOON. BROKEN TO OVERCAST LOW CLOUDS HAVE BEEN SPREADING
SE TOWARD I-70 EARLY THIS MORNING ALONG WITH ISOLATED TO SCATTERED
LIGHT RAIN SHOWERS OVER NORTHERN IL MAINLY NORTH OF I-80 SO FAR.
THESE LIGHT SHOWERS ARE NORTH OF A FRONTAL TROF EXTENDING FROM
1004 MB LOW PRESSURE OVER SE ONTARIO THROUGH SOUTHERN LOWER MI
INTO NORTHERN IL NEAR I-80 AND INTO SOUTHERN IA. AS UPPER LEVEL
TROF AND SURFACE TROF SWING SE THROUGH CENTRAL IL THIS MORNING
EXPECT A FEW LIGHT RAIN SHOWERS TO OCCUR...THEN DIMINISH FROM NW
TO SE DURING THE AFTERNOON AS LOW CLOUDS CLEAR OVER THE IL RIVER
VALLEY LATER THIS AFTERNOON AND OVER EASTERN IL DURING THIS
EVENING. COOL TODAY FOR LATE MAY WITH HIGHS IN THE LOW TO MID 60S
OVER CENTRAL IL AND 65 TO 70F IN SE IL FROM I-70 SE. NNW BREEZES
TO MAKE IT FEEL EVEN COOLER TODAY.

1034 MB CANADIAN HIGH PRESSURE OVER NORTHERN MANITOBA AND RIDGING
SOUTHWARD INTO THE CENTRAL/NORTHERN PLAINS TO SETTLE INTO WI AND
NE IL AS 1031 MB HIGH PRESSURE OVERNIGHT BRINGING A COOL NIGHT TO
CENTRAL IL AS SKIES CLEAR AND WINDS BECOME LIGHT WITH LOWS IN THE
UPPER 30S AND LOWER 40S. HIGH PRESSURE RIDGE STAYS OVER LAKE MI
AND EASTERN IL FRI PROVIDING SUNNY SKIES AND NE WINDS LESS THAN 10
MPH AND HIGHS IN THE MID TO UPPER 60S. DRY WEATHER SHOULD CONTINUE
ACROSS CENTRAL/SE IL THROUGH FRIDAY EVENING WITH SURFACE RIDGE
NEARBY.

LONG TERM...SATURDAY THROUGH THURSDAY

UPPER LEVEL RIDGE SETS UP OVER THE GREAT PLAINS BY THIS MEMORIAL
DAY WEEKEND WITH UPPER LEVEL LOW/TROF MOVING INTO NEW ENGLAND BY
SAT. THIS PUTS IL IN A NW UPPER LEVEL FLOW AND MODELS CONTINUE TO
SHOW UPPER LEVEL DISTURBANCES RIDING SE ALONG THERMAL GRADIENT
NEAR CENTRAL IL THIS HOLIDAY WEEKEND. HAVE 20-30% CHANCE OF
SHOWERS AND ISOLATED THUNDERSTORMS NW OF I-55 AFTER MIDNIGHT
FRIDAY NIGHT. THEN SPREAD A 30-50% CHANCE OF SHOWERS AND
THUNDERSTORMS EASTWARD ACROSS CENTRAL AND WESTERN IL SAT (SLIGHT
CHANCE OVER EASTERN/SE IL SAT AFTERNOON) AND INTO EASTERN IL BY
SAT NIGHT. LOOKS LIKE 30-40% CHANCE OF SHOWERS AND THUNDERSTORMS
CONTINUES MONDAY AND TUE OVER MUCH OF AREA WITH THE LOWER POPS
NEAR THE WABASH RIVER. SURFACE HIGH PRESSURE OVER THE GREAT LAKES
AND INTO THE CENTRAL/EASTERN OHIO VALLEY TO ALSO KEEP AREAS NE OF
CENTRAL IL DRIER THIS HOLIDAY WEEKEND. UPPER LEVEL RIDGE SHIFTS
EAST INTO THE OHIO VALLEY BY MIDDLE OF NEXT WEEK AND SHIFTS
CHANCES OF CONVECTION NORTH OF CENTRAL IL. TEMPERATURES AND
HUMIDITY LEVELS TO GRADUALLY INCREASE ALSO FROM SUN-WED WITH HIGHS
IN THE UPPER 60S AND LOWER 70S SUNDAY AND CLIMBING TO AROUND 80F
TUE AND LOW TO MID 80S WED.

07

&&

.AVIATION...
ISSUED 1105 PM CDT WED MAY 22 2013

LITTLE CHANGE IN THINKING FROM PREVIOUS DISCUSSION...TIMING OF
LOWER CIGS INTO OUR AREA LATE TONIGHT THE MAIN FORECAST CHALLENGE.
MVFR CIGS WERE LOCATED OVER EXTREME EASTERN IOWA AND PARTS OF
NW IL LATE THIS EVENING AND WERE TRACKING SLOWLY SOUTHEAST ALONG
A WEAK SURFACE BOUNDARY. WE SHOULD START TO SEE THE CIGS LOWER TO
MVFR AT ALL SITES STARTING AFTR 06Z AT KPIA AND BY 09Z OVER AT KCMI.
ONCE THEY LOWER TO MVFR...THE CIGS SHOULD REMAIN THERE THRU THU
AFTERNOON BEFORE WE SEE A GRADUAL IMPROVEMENT TO VFR THU EVENING.
MAY SEE SOME TEMPO IFR CIGS AT PIA AND BMI LATE TONIGHT...MORE
LIKELY AFTR 10Z...WHICH WOULD CONTINUE THRU THE MID MORNING HOURS.

REGIONAL RADAR LOOP CONTINUES TO SHOW QUITE A BIT OF RAIN ALONG AND
NORTH OF THE SFC TROF WHICH WILL SHIFT INTO OUR AREA AROUND 12Z IN
PIA AND POINTS FURTHER EAST BY 15Z THU. WILL CONTINUE TO INDICATE
VCSH AT THE TAF SITES FOR NOW. LOOK FOR WINDS TO REMAIN FROM A WESTERLY
DIRECTION AHEAD OF THE SFC TROF AXIS TONIGHT AT SPEEDS OF 10 KTS OR
LESS...AND THEN SWITCH INTO THE NORTHWEST AND THEN NORTH ON THURSDAY
WITH WINDS INCREASING TO BETWEEN 12 AND 17 KTS BY AFTN...WITH GUSTS
UP TO 25KTS AT TIMES IN THE AFTN BEFORE THEY SLOW BEGIN TO DECREASE
AFTER DARK THU EVENING.

SMITH

&&

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

&&

$$