Area Forecast Discussion
Issued by NWS Central Illinois

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854
FXUS63 KILX 161147
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
647 AM CDT SAT MAY 16 2015

.SHORT TERM...(TODAY)
ISSUED AT 336 AM CDT SAT MAY 16 2015

ANOTHER RELATIVELY WARM AND HUMID DAY IS ANTICIPATED ACROSS CENTRAL
AND SOUTHEAST ILLINOIS TODAY AS SOUTHERLY LOW LEVEL FLOW PERSISTS.
DAYTIME HIGHS MAY BE A FEW DEGREES COOLER THAN YESTERDAY, ESPECIALLY
ACROSS SOUTHEAST ILLINOIS WHERE CLOUD COVER WILL BE THICKEST AND
RAINFALL MOST WIDESPREAD, BUT MOST LOCATIONS SHOULD STILL CRACK THE
80 DEGREE MARK.

AS FAR AS SHOWER/STORM POTENTIAL TODAY, GIVEN THE FAIRLY JUICED UP
LOW-LEVEL AIRMASS AND LACK OF APPRECIABLE CAPPING, IT WILL NOT TAKE
MUCH TO POP OFF SOME CONVECTION. PLAN TO CARRY AT LEAST CHANCE POPS
AREAWIDE TODAY GIVEN THIS POTENTIAL. MODEL PROGS SUGGEST MOST OF THE
FORECAST AREA SHOULD SEE DIURNALLY INDUCED CAPE VALUES OF AT 1500
J/KG, ALTHOUGH SHEAR PROFILES SHOULD BE QUITE WEAK OVER THE NORTHERN
2/3 OR SO OF THE REGION. THE BETTER FORCING ACROSS SOUTHEAST
ILLINOIS WILL COME COURTESY OF A WEAK SHORT WAVE LIFTING NORTHEAST
FROM THE MID-MISSISSIPPI RIVER VALLEY. HAVE BUMPED POPS UP TO
CATEGORICAL SOUTH OF I-70 FOR THE MIDDAY/EARLY AFTERNOON HOURS TO
ACCOUNT FOR THE PASSAGE OF THIS WAVE.

.LONG TERM...(TONIGHT THROUGH FRIDAY)
ISSUED AT 336 AM CDT SAT MAY 16 2015

DIURNALLY ENHNANCED CONVECTION THIS AFTERNOON AND EARLY EVENING WILL
DIMINISH IN COVERAGE AFTER SUNSET SIMILAR TO WHAT HAPPENED FRIDAY
EVENING AS INSTABILITY WANES. WILL CARRY HIGHEST POPS IN
SOUTHEAST IL THIS EVENING ESPECIALLY BEFORE DARK WITH SHORT WAVES
NEAR EASTERN/SE IL EARLY THIS EVENING AROUND 00Z/7 PM. MILD LOWS
TONIGHT IN THE MID TO UPPER 60S WITH MILDEST READINGS SW AREAS.

CUTOFF LOW OVER THE CENTRAL ROCKIES TO EJECT NE INTO MN BY SUNDAY
EVENING AND HAS A PREFRONTAL TROF PUSHING EAST TOWARD THE MS RIVER.
THIS TO INCREASE CHANCES OF CONVECTION FROM WEST TO EAST DURING THE
DAY SUNDAY AND THEN DIMINISH FROM WEST TO EAST DURING SUNDAY NIGHT.
SPC HAS SLIGHT RISK OF SEVERE STORMS SUNDAY AFTERNOON/EVENING FROM
BLOOMINGTON TO TAYLORVILLE WEST WHERE STRONGER BULK SHEAR OF 35-45
KTS OCCURS ALONG WITH INCREASE INSTABILITY WITH CAPES PEAKING AROUND
2500 J/KG SUNDAY AFTERNOON. WARM HIGHS IN THE LOWER 80S SUNDAY WITH
BREEZY SSW WINDS AND MUGGY DEWPOINTS IN THE MID TO UPPER 60S.

MAIN COLD FRONT TO PUSH EAST ACROSS IL DURING MONDAY AND BRINGS BEST
CHANCES OF SHOWERS AND THUNDERSTORMS TO AREAS EAST OF I-55. SPC
KEEPS MARGINAL RISK OF SEVERE EAST OF IL OVER PARTS OF INDIANA ON
MONDAY. HAVE BUMPED UP THE HIGHS ON MONDAY A FEW DEGREES WITH MID
70S FROM IL RIVER NW TO LOWER 80S IN EASTERN IL.

DRIER...COOLER AND LESS HUMID AIR USHERS INTO IL DURING MONDAY NIGHT
AND TUE BEHIND THE COLD FRONT. LOWS MONDAY NIGHT RANGE FROM MID 40S
NW OF IL RIVER TO NEAR 55F FAR SE IL NEAR WABASH RIVER BY
LAWRENCVILLE. HIGHS TUE IN THE MID 60S CENTRAL IL AND 65-70F IN
SOUTHEAST IL. A COOL NIGHT AHEAD FOR TUE NIGHT WITH LOWS IN THE MID
TO UPPER 40S.

EXTENDED MODELS TRY TO BRING SOME QPF BACK INTO PARTS OF CENTRAL AND
ESPECIALLY SOUTHERN/SW IL WED AND THEN SUPPRESS IS SOUTHWARD BY THU
WITH SOME ENERGY EJECTING FROM THE UPPER LEVEL TROF/LOW NEAR CA AND
MOVING INTO THE MID/LOWER MS RIVER VALLEY. WILL KEEP POPS LOW FROM
WED-THU WITH MAINLY SLIGHT CHANCES, THOUGH SW AREAS HAVE CHANCE POPS
30-40% WED AND WED EVENING. HIGHS IN THE LOW TO MID 60S WED AND 65
TO 70F ON THU. TEMPS CONTINUE TO SLOWLY MODIFY FRIDAY WITH HIGHS
MAINLY IN THE LOWER 70S AND DRY CONDITIONS WITH WEAK HIGH PRESSURE
IN THE CENTRAL PLAINS AND RIDGING EAST TOWARD IL.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 639 AM CDT SAT MAY 16 2015

AREAS OF IFR STRATUS AND FOG HAVE DEVELOPED ACROSS CENTRAL
ILLINOIS EARLY THIS MORNING. THIS STRATUS/FOG SHOULD BURN OFF
WITHIN THE NEXT FEW HOURS AS DIURNAL HEATING INCREASES. THEN,
ATTENTION TURNS TO AN UPPER LEVEL DISTURBANCE LIFTING NORTHEAST
INTO THE AREA. THIS DISTURBANCE SHOULD PRODUCE AT LEAST SCATTERED
SHOWERS/STORMS TODAY AS IT MOVES THROUGH, WITH KDEC & KCMI THE
MOST LIKELY OF THE LOCAL TERMINALS TO BE IMPACTED. HAVE INCLUDED A
4 HOUR TEMPO FOR THUNDER AT THOSE LOCATIONS DURING THE PREFERRED
TIME PERIOD, BUT ONLY INCLUDED A VCTS AT KPIA, KBMI, AND KSPI AS
THE STORM COVERAGE SHOULD BE MORE SPOTTY FURTHER WEST. CAN`T RULE
OUT SOME CONVECTION POPPING UP OUTSIDE THE FAVORED DIURNAL HEATING
PERIOD, WHICH OVERLAPS TODAY WITH THE PASSAGE OF THE DISTURBANCE,
BUT EXPECTED COVERAGE IS TOO LOW TO MENTION AT THIS TIME. AS THE
AIRMASS, CLOUD, AND WIND CONDITIONS SHOULD BE SIMILAR TONIGHT TO
EARLY THIS MORNING, PLAN TO HAVE IFR CONDTIONS DEVELOPING ONCE
AGAIN LATER TONIGHT.

&&

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

$$

SHORT TERM...BAK
LONG TERM...07
AVIATION...BAK



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