000 FXUS63 KILX 111114 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 614 AM CDT MON MAY 11 2009 .DISCUSSION... ISSUED 307 AM CDT MON MAY 11 2009 WEAK SFC LOW PUSHING EAST OF LAKE MICHIGAN THIS MORNING...WITH SMALL SFC TROF MOVING THE REMNANTS OF THE DWINDLING OVERNIGHT SHOWERS FURTHER SOUTH AS WELL. SLIGHT RIDGING IN THE WESTERN CONUS...AND MORE ZONAL FLOW OVER THE ERN HALF...MUCH OF ILLINOIS IS CAUGHT JUST EAST OF THE INFLECTION POINT...ONE 250 MB JET STREAK EXITING...ONE MOVING IN. WEAK HIGH PRESSURE FROM THE GREAT LAKES INTO THE SOUTHERN PLAINS NOT DOING MUCH TO TAMP DOWN THE ACTIVITY BEHIND THE FRONT TO THE SOUTH ACROSS THE GULF STATES. ISSUES FOR THE FORECAST ARE MAINLY THE SYSTEM FROM TUES NIGHT TO WED NIGHT... AND THE NEXT CHANCE BEYOND THAT IS FRI/FRI NIGHT. MODELS ARE DOING MODERATELY WELL WITH THE FIRST SYSTEM...AND THE FORECAST LEANS A LITTLE HEAVIER ON THE GFS SOLUTION. HOWEVER...THE LATE WEEK SYSTEM IS STILL A BIT INCONSISTENT RUN TO RUN IN ANY GIVEN OPERATIONAL MODEL. SO THE GOING FORECAST IS A RATHER CONSERVATIVE REPRESENTATION OF A BLEND BETWEEN THE GFS AND THE CANADIAN. SHORT TERM...TODAY AND TOMORROW... RELATIVELY QUIET ALL IN ALL. EXPECT SHOWER RISK SHOULD SINK SOUTH FURTHER IN THE EARLY MORNING HOURS... AND CLEARING LINE OF THE MID LEVEL CLOUDS IS CROSSING THE MISS RIVER VALLEY. AFTERNOON CU EXPECTED...AND TEMPS TO SLOWLY WARM OVER THE NEXT TWO DAYS. WINDS WEAK IN GENERAL TODAY...SLOWLY ADDING A SOUTHERLY COMPONENT...MORE SOUTHEASTERLY TONIGHT...THEN MUCH MORE SOUTHERLY LATE AFTERNOON TUESDAY AS THE WARMER GULF MOISTURE STARTS PUSHING INTO THE MIDWEST AS WELL. BY LATE TUESDAY NIGHT...A WARM FRONTAL BOUNDARY IS TRYING TO SET UP IN THE REGION... PUSHING NORTH. THE GFS IS SHOWING A MUCH FURTHER NORTHERLY PROGRESSION OF THE DEVELOPING BOUNDARY IN THE OVERNIGHT TUESDAY...WHICH IS CRUCIAL TO WEDNESDAY. LONG TERM...WEDNESDAY THROUGH FRIDAY... WITH BOTH THE NAM AND THE GFS PUTTING ILX IN A WARM SECTOR...SPC IS FOLLOWING SUIT AND PUTTING A MODERATE RISK FOR SEVERE WEATHER OVER ALMOST THE ENTIRE CWA FOR WEDNESDAY. BEARS MENTIONING THAT THE ECMWF IS A BIT SLOWER WITH THE PROGRESSION OF THE WARM FRONT...WHICH WOULD RESULT IN A CLOUDIER DAY...AND LESS SFC BASED INSTABILITY TO FUEL THE SITUATION. THAT BEING SAID...CURRENT FORECAST IS FAVORING THE NAM/GFS SOLUTION. THE DWPTS ARE IN THE LOW 60S BY MID DAY WEDNESDAY WITH THE GOING FORECAST...WARM SECTOR ENVIRONMENT WITH PLENTY OF SFC INSTABILITY...AND WIND PROFILES FAVORABLE FOR SUPERCELL DEVELOPMENT. PRECIP LIKELY TO CONTINUE THROUGH WED AND WED NIGHT AS THE COLD FRONT MAKES ITS WAY THROUGH THE CWA. NOT COMFORTABLE ENOUGH WITH THE LOCATION AND TIMING OF ALLEGED DRY SLOT IN THE MODELS (MOSTLY THE GFS) TO PIN POINT THE BREAK IN PRECIP WED AFTERNOON AHEAD OF THE COLD FRONT...ESPECIALLY WITH SUCH ACTIVE CONVECTION LIKELY. FRIDAYS SYSTEM A LITTLE BIT BLURRY AT THIS POINT IN THE WAKE OF WED CONVECTION AND THE DRIFTING FRONTAL BOUNDARY. MODELS SEEM CONTENT TO STRING OUT THE FRONT IN THE MIDSECTION OF THE CONUS...SOUTH OF ILLINOIS...AND THEN PUSH BACK NORTH AS LLVL WAA KICKS IN LATE FRIDAY. TIMING OF THE BEST WAA WILL MAKE A HUGE DIFFERENCE IN WHERE THE FRONT SETS UP. PREVIOUS ENSEMBLE RUNS AND THE PREV AND CURRENT CANADIAN DELAY THE PRECIP...WITH THE BAROCLINIC ZONE SETTING UP A BIT FURTHER TO THE NORTH. KEEPING POPS LOW FOR NOW...BEST POPS DELAYED TO FRIDAY NIGHT...FOR NOW. && .AVIATION... ISSUED 614 AM CDT MON MAY 11 2009 VFR CONDITIONS WILL CONTINUE NEXT 24HRS AT ALL TAF SITES. CLOUD COVER ASSOCIATED WITH THE WEAK WAVE THAT MOVED THROUGH THE CWA LAST NIGHT IS FINALLY MOVING OUT OF THE REGION AND ONLY DEC AND CMI HAVE ANY MID OR HIGH CLOUDS OVER THEM AT THE MOMENT. WILL START BOTH OF THEM WITH CLOUDS BUT THEN DECREASE TO JUST CIRRUS AT 13Z. CU RULE INDICATES THAT SOME SCT CU IS POSSIBLE TODAY BUT NOT ENOUGH FOR BKN. THE CLEAR SKIES RETURN FOR TONIGHT. WINDS WILL REMAIN LIGHT GIVEN THE PROXIMITY OF THE HIGH PRSS AREA THROUGH THE PERIOD. HOWEVER...COULD SEE SOME WINDS OF 10KTS OR LESS OUT OF THE NORTH TODAY AS THE HIGH PRSS RIDGE STARTS JUST WEST OF THE AREA. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$