000
FXUS63 KILX 210610
AFDILX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
ISSUED BY NATIONAL WEATHER SERVICE ST LOUIS MO
110 AM CDT TUE MAY 21 2013

.DISCUSSION...
ISSUED 845 PM CDT MON MAY 20 2013

UPDATED THE FORECAST TONIGHT TO EXPAND THE TORNADO WATCH UNTIL 1
AM FROM MCLEAN...DEWITT...MACON AND CHRISTIAN COUNTIES WEST.
INCREASED TO CATEGORICAL POPS OF 80-100% FROM I-55 WEST THROUGH 1
AM INCLUDING RISK OF TORNADOES...LARGE HAIL...DAMAGING WIND GUSTS...
HEAVY RAINS AND FREQUENT LIGHTNING. HAVE CHANCE OF SHOWERS AND
THUNDERSTORMS DEVELOPING OVER EASTERN IL LATE THIS EVENING AND
CONTINUE LIKELY CHANCES OF SHOWERS AND THUNDERSTORMS OVERNIGHT
WHERE STRONG TO SEVERE STORMS POSSIBLE AS WELL AFTER MIDNIGHT OVER
EASTERN IL.

996 MB LOW PRESSURE OVER NE SD WITH WARM FRONT OVER NORTHERN WI/MI
AND ITS COLD FRONT OVER SW MN...WESTERN IA INTO SE KS AND CENTRAL OK.
STRONG 556 DM 500 MB LOW WAS ALSO OVER NE SD. SCATTERED TO
NUMEROUS STRONG TO SEVERE THUNDERSTORMS WAS SE OF THIS LARGE LOW
PRESSURE SYSTEM FROM THE IL RIVER VALLEY THRU CENTRAL MO INTO SE
OK AND CENTRAL TX. CONVECTION WAS AS FAR EAST AS I-55 AND RACING
NE AT 40 TO 50 MPH. SHORT WAVE EJECTING NE FROM OK AND OZARKS OF
NW AR AND SW MO INTO CENTRAL IL DURING TONIGHT TO PRODUCE
WIDESPREAD CONVECTION ACROSS CENTRAL AND EVENTUALLY EASTERN IL BY
OVERNIGHT. MUCH OF IL REMAINS IN SLIGHT RISK OF SEVERE STORMS
TONIGHT THROUGH TUE WHILE MODERATE RISK OF SEVERE STORMS TONIGHT
OVER SOUTHERN MO. THERE IS 30% RISK OF LARGE HAIL AND DAMAGING
WIND GUSTS OVER CENTRAL IL TONIGHT ESPECIALLY FROM I-57 WEST AND
5-10% RISK OF TORNADOES WITH SUPERCELLS. SPC SAID MCS TO EVOLVE
INTO QLCS DURING THIS EVENING AND CONTINUE RISK OF SEVERE STORMS
INTO CENTRAL IL TONIGHT. INCREASE QPF TONIGHT OVER CENTRAL IL WITH
AVERAGE HALF TO 1 INCH AMOUNTS AND LOCALLY 1-2 INCH AMOUNTS WITH
STRONGER STORMS. LOWS IN THE MIDDLE TO UPPER 60S BY DAWN.

07


&&

.AVIATION...
ISSUED 109 AM CDT TUE MAY 21 2013

MOST INTENSE CONVECTION ALONG OUTFLOW BOUNDARY HAS WEAKENED
CONSIDERABLY AS ITS MOVED INTO SE SECTIONS OF CWA...AND OVER THE
NEXT FEW HOURS ELEVATED...AND GENERALLY LIGHT...CONVECTION WILL BE
TAPERING OFF ALONG AND EAST OF A BMI-DEC LINE.  SOME LIGHTER
ELEVATED SHOWERS WORKING INTO EASTERN MISSOURI SHOULD RETURN TO THE
AREA DURING THE PREDAWN HOURS...AND WILL ALSO NEED TO KEEP AN EYE ON
SOME ELEVATED CONVECTION REFIRING AS LOW LEVEL S FLOW INTENSIFIES
AND TAPS RESIDUAL INSTABILITY BUT FOR NOW HAVE HELD THESE OUT OF THE
TAFS.  ONCE THE HEAVIER CONVECTION EXITS E TAFS BY 08Z...VFR
CONDITIONS SHOULD PREVAIL WITH CIGS AOA 8KFT...WITH PERHAPS A BIT OF
ST FORMING DURING THE PREDAWN HOURS AND HAVE HINTED AT THAT WITH SCT
3KFT.  NOT MANY CHANGES MADE TO FORECASTS FOR LATER TODAY...WITH SCT
CU FORMING BY MID MORNING.  DUE TO UNCERTAINTY OF TIMING/LOCATION OF
CONVECTIVE INITIATION...WILL LET NEXT SHIFT MONITOR TRENDS BEFORE
INTRODUCING NEXT ROUND OF STORMS.

TRUETT

&&

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

$$