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.
&&

$$