929 FXUS63 KILX 311150 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 650 AM CDT FRI MAY 31 2013 .DISCUSSION... ISSUED 325 AM CDT FRI MAY 31 2013 SHORT TERM...TODAY THROUGH SUNDAY 07Z SURFACE MAP SHOWED LITTLE CHANGE FROM 24 HRS AGO WITH A LOW PRESSURE COMPLEX STRETCHED ALONG THE PLAINS...WITH THE DOMINANT LOW OVER NORTH CENTRAL SD. ALOFT A VIGOROUS CLOSED LOW AT 500 MB WAS SPINNING OVER THE DAKOTAS AND SENDING SHORTWAVES EAST INTO THE MIDWEST. THIS SPARKED SEVERE STORMS LAST NIGHT AND CONTINUES TO PRODUCE LOCALLY HEAVY RAIN OVER THE EASTERN CWA EARLY THIS MORNING. ANOTHER SHORTWAVE SLIDING INTO THE KS/NEB BORDER REGION IS ALREADY IGNITING ANOTHER ROUND OF THUNDERSTORMS IN NE KS. WITH SUPPORT FROM A 40-50 KT SW LLJ THIS COMPLEX IS EXPECTED TO GROW UPSCALE THROUGH THIS MORNING AND REACH INTO WESTERN IL AROUND 14-15Z. FOR CONVECTIVE TRENDS TODAY HAVE CLOSELY FOLLOWED THE 4KM NSSL WRF WHICH HAS PERFORMED WELL THE PAST COUPLE DAYS...AND ALSO LOOKS SIMILAR TO THE 4KM LSX ARW-WRF. THESE MODELS WOULD SUGGEST THIS COMPLEX AFFECTING THE NORTHWEST HALF OF THE CWA THROUGH EARLY AFTERNOON...THEN DEVELOPMENT ALONG THE LEADING EDGE OF THE OUTFLOW AFFECTING THE CENTRAL AND SOUTHERN CWA INTO THIS EVENING. LOOKING AT SEVERE WX PARAMETERS...45-55 KT 0-6KM BULK SHEAR AND SURFACE BASED CAPES IN EXCESS OF 2K J/KG WOULD SUPPORT ORGANIZATION FOR A SQUALL LINE OR QLCS TYPE EVENT. ANY LOCAL BACKING OF THE SFC FLOW WOULD SUPPORT AN ISOLATED TORNADO THREAT. OF COURSE THE EVOLUTION OF THE EXPECTED MCS TO OUR WEST WILL BE KEY TO DEVELOPMENT LATER TODAY...AS A CONVECTIVELY OVERTURNED AIRMASS AND/OR CAPE REDUCING DENSE OVERCAST MAKE THE SEVERE TRENDS MORE COMPLICATED. HEAVY RAIN RATES ARE POSSIBLE ONCE AGAIN...AND WITH 1.5-1.8 INCH PRECIPITABLE WATER THE THE POTENTIAL FOR TRAINING CELLS HAVE EXPANDED THE FLASH FLOOD WATCH TO COVER THE ENTIRE CWA RUNNING THROUGH 00Z/SUN. THE COLD FRONT IS FORECAST TO PUSH ACROSS THE CWA ON SATURDAY AND PRODUCE ANOTHER ROUND OF LOCALLY HEAVY RAIN AND POSSIBLE SEVERE STORMS. BASED ON TIMING THE CENTRAL AND EASTERN CWA PRIMARILY EAST OF I-55 LOOK MOST SUSCEPTIBLE FOR MORE INTENSE ACTIVITY. THE POST-FRONTAL AIRMASS WILL BRING MUCH COOLER AIR INTO THE MIDWEST ON SUNDAY. HAVE ADDED A SLIGHT CHANCE OF SHOWERS AS LLVL MOISTURE LINGERS AND ANOTHER SHORTWAVE ROTATES AROUND THE GREAT LAKES TROF IN CYCLONIC FLOW. LONG TERM...MONDAY THROUGH THURSDAY CANADIAN HIGH PRESSURE SHIFTING ACROSS THE GREAT LAKES IS EXPECTED TO PRODUCE QUIET AND SEASONABLY COOL WEATHER INTO TUESDAY. HOWEVER BY MID-WEEK ANOTHER CLOSED MID LEVEL LOW IS FORECAST TO MOVE INTO THE NORTHERN PLAINS. THIS WILL SPIN UP ANOTHER PLAINS SFC LOW...AND WARM ADVECTION PRECIP WILL SPREAD EAST ACROSS THE REGION. THIS LOOKS TO BE ANOTHER SLOW MOVING SYSTEM WITH POPS LINGERING THURSDAY AND LIKELY BEYOND. SYSTEM SHOULD NOT BE AS INTENSE AS THE LAST FEW WE HAVE DEALT WITH AS A SUB-TROPICAL RIDGE OVER NORTHERN MEXICO LIMITS DEEP MOISTURE FEED. && .AVIATION... ISSUED 644 AM CDT FRI MAY 31 2013 A SLIGHT SHIFT IN THE FORECAST THIS MORNING AS THE HIGH RES MODELS SHOWING THE PROGRESSION OF A COMPLEX IN NRN MO PUSHING INTO CENTRAL IL THIS MORNING AND MOVING THE TIME TABLE UP A BIT. PUTTING TEMPO GROUPS IN FOR THE TIME FRAME SURROUNDING 16Z TO 20Z...LINGERING RAIN A LITTLE LONGER THROUGH CENTRAL IL...THEN DRIVING PRECIP SOUTH. TROUBLE STILL REMAINS WITH THE POTENTIAL FOR THE ATMOSPHERE TO RECOVER AND REFIRE LATER IN THE EVENING WITH ANOTHER ROUND. SINCE 4KM MODELS STARTING TO LOOK WORKED OVER...HAVE OPTED FOR A SIMPLE VCTS MENTION THROUGH THE AFTERNOON. FOR NOW...CIGS MOSTLY IN THE VFR EXCEPT WITH THE TS. BRISK SOUTHERLY WINDS YET AGAIN WITH STOUT GUSTS TO 28-30KT. HJS && .ILX WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH SATURDAY EVENING FOR ILZ027>031- 036>038-040>057-061>063-066>068-071>073. && $$