841 FXUS63 KILX 220307 AFDILX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 905 PM CST SAT FEB 21 2004 .DISCUSSION... LARGE HIGH PRESSURE AREA CENTERED OVER MIDWEST HAS BROUGH FAIR SKIES AND CALM WINDS TO CNTRL IL. REMAINING LOW CLOUDS FINALLY LEAVING ERN IL AND SERN IL THIS HOUR. TEMPERATURES SHOULD CONTINUE TO FALL OVERNIGHT...REACHING TO AROUND CURRENT DEWPOINTS. COMBINE LOW TEMPS IN THE MID 20S WITH CALM WINDS AND CLEAR SKIES...AND THERE IS A NICE SETUP FOR PATCHY FOG TO DEVELOP ACROSS THE AREA OVERNIGHT. CURRENT FORECAST HAS A GOOD HANDLE ON ALL THIS...SO THERE WILL BE NO UPDATE AT THIS TIME. && .PREVIOUS DISCUSSION... HIGHLY AMPLIFIED SPLIT FLOW PATTERN ACRS NORTH AMERICA CONTINUES TO PRODUCE PROBLEMS WITH EACH MODEL RUN REGARDING THE NEXT COUPLE OF WX SYSTEMS TO AFFECT CENTRAL IL. STILL QUITE A BIT OF SPREAD IN THE ENSEMBLES AGAIN THIS MRNG REGARDING SPEED AND STRENGTH OF FIRST SYSTEM SUNDAY NIGHT INTO MONDAY...AND SOME REAL DISAGREEMENT WITH THE STRONG SRN STREAM SYSTEM FCST TO MOVE ACRS THE GULF COAST STATES AND SWING NE INTO THE EASTERN US. MAIN FCST CHALLENGES THE NEXT SVL DAYS WILL BE TIMING AND TYPE OF PRECIP SUNDAY NIGHT INTO MONDAY...WITH NRN EXTENT OF PRECIP SHIELD A CHALLENGE FOR THE MIDWEEK SYSTEM. WITH SUCH A HIGHLY AMPLIFIED PATTERN DEPICTED ACRS THE CONUS THE NEXT WEEK...WL TEND TO SIDE WITH THE SLOWER GFS WITH OUR FIRST SYSTEM EARLY IN THE WEEK...AND CONTINUE TO FAVOR THE ECMWFS MORE SRN SUPPRESED LOOK WITH THE MIDWEEK SYSTEM. SHORT TERM...TONIGHT THROUGH TUESDAY... HIGH PRESSURE CONTINUES TO EDGE EASTWARD OUT OF PLAINS THIS AFTN AND THIS SHOULD CONTINUE TO PUSH TOWARDS OUR FCST AREA OVERNIGHT. VSBL LOOP SHOWING BACK EDGE OF CLOUD SHIELD LOOKING MORE CELLULAR EARLY THIS AFTN SUGGESTING A RAPID DECREASE IN CLOUDS THIS EVENING FROM WEST TO EAST. BNDRY LAYER WINDS NOW BECOMING MORE WESTERLY THIS AFTN WITH UPSTREAM DEW POINTS NOT SHOWING MUCH OF A DECREASE UNDERNEATH HIGH...SO POTENTIAL EXISTS FOR SOME PATCHY FOG TO FORM LATER TNT IF MID AND HIGH CLOUDS FROM NEXT SYSTEM DONT PUSH IN TOO QUICKLY. GUID NUMBERS LOOK REASONABLE TNT. NEXT WEATHER SYSTEM DROPS SOUTHEAST OUT OF CANADA AND MERGES WITH A PIECE OF ENERGY EJECTING OUT OF THE SW LATE SUNDAY AND BEGINS TO AFFECT OUR AREA BY EVENING. FCST SOUNDINGS OFF THE ETA AND GFS SUPPORT MOSTLY LIQUID EXCEPT IN OUR FAR NRN COUNTIES WHERE A MIX MAY OCCUR AT THE ONSET OF THE PRECIP...WITH A TREND TOWARDS ALL LIQUID PRECIP BY MONDAY MORNING AHEAD OF THE INVERTED TROF. WILL BUMP POPS UP TO LIKELY BY LATE EVENING SUNDAY ACRS THE WEST AND NORTH...WITH LOWEST POPS ACRS OUR SOUTHEAST. USING THE SLOWER GFS WITH THIS SYSTEM WILL KEEP PRECIP GOING INTO MONDAY NIGHT WITH A DECREASE IN POPS FROM NORTH TO SOUTH ON TUESDAY. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY... MODELS HAVING THEIR USUAL PROBLEMS WITH DECIDING WHETHER TO PHASE THE NRN AND SRN STREAMS AND JUST WHERE AND WHEN THAT WILL OCCUR...IF AT ALL. WATER VAPOR LOOP DEPICTING STRONG JET OVR THE CNTRL PACIFIC DIGGING SHARPLY SE WHICH WOULD TAKE THE MAIN CORE OF STRONG WINDS SOUTH OF BAJA. MEDIUM RANGE MODELS INDICATING CENTER OF CURRENT TO REMAIN ACRS THE GULF STATES WITH MAIN LOW LVL BAROCLINIC ZONE ASSOCIATED WITH MID WEEK SYSTEM...SO WIL CONTINUE WITH PREVIOUS TRENDS OF KEEPING POPS GOING MAINLY ALONG AND SOUTH OF I-70. AS ENERGY TRANSLATES TO EAST COAST LATE WEDNESDAY...UPPER LVL RIDGING SHOULD BUILD ACRS THE MIDWEST WITH TEMPS AVERAGING AT OR ABOVE NORMAL WITH LITTLE CHANCE OF ANY SIG RAIN OR SNOW. AFTER WEDNESDAYS CHANCE OF PRECIP ACRS THE SE THIRD...WL KEEP THE REMAINDER OF THE EXTENDED FCST DRY. && .ILX WATCHES/WARNINGS/ADVISORIES... IL...NONE. && $$ AUTEN/SMITH