000 FXUS63 KEAX 240250 AFDEAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 845 PM CST TUE NOV 23 2004 ...WINTER WEATHER ADVISORY FOR PORTIONS OF EAST CENTRAL KANSAS THROUGH NORTH CENTRAL AND CENTRAL MISSOURI FOR WEDNESDAY... .DISCUSSION... MAY NEED TO EXTEND WINTER WEATHER ADVISORY FURTHER NORTH TO INCLUDE WEST CENTRAL MO(KC AREA)/EAST CENTRAL KS. DEFORMATION ZONE INITIALLY SETTING UP FURTHER NORTH AS SEEN ON ENHANCED CLOUDS IN SATELLITE LOOP. UPSTREAM RADAR DATA SHOWS BRIGHT BANDING OCCURRING OVER CENTRAL KS WITH SLEET REPORTED. SO WE MAY GET SOME SLEET TO START OFF WITH AROUND MIDNIGHT BEFORE CHANGING TO SNOW. 00Z ETA QPF AND SNOW ALGORITHMS PROG FASTER COOLING OVER WEST CENTRAL MO WITH CHANGE OVER TO SNOW OCCURRING SHORTLY AFTER MIDNIGHT. PRECIPITATION ALSO ENDS FASTER OVER WEST CENTRAL MO...SHORTLY AFTER 12Z. ALSO NOTICED COMMA HEAD FORMING FROM NORTHWEST TX INTO SOUTHWEST OK WHICH IS INDEPENDENT OF ABOVE MENTIONED DEFORMATION FIELD...SO WE COULD END UP SEEING THE NORTHERN DEFORMATION FIELD FALL APART BETWEEN 09Z-12Z AS SOUTHERN COMMA HEAD DEVELOPS AND SPREADS NORTHEAST ACROSS SOUTHEAST KS AND INTO SOUTHWEST/CENTRAL MO TOMORROW MORNING. THE FRONTOGENETIC FIELDS FROM 850MB-650MB SUGGEST THIS MAY OCCUR. STAY TUNED FOR POSSIBLE CHANGE TO ADVISORY. MJ && .PREV DISCUSSION... 348 PM... MAIN FOCUS OF TODAYS FORECAST IS ON THE IMPENDING WINTER WEATHER AS A LOW EJECTS OUT OF THE DESERT SOUTHWEST THROUGH THE LOWER MISSOURI RIVER VALLEY TONIGHT AND TOMORROW. BOTH THE GFS AND ETA MODELS DID A GOOD JOB OF INITIALIZING THE POSITION OF THE CUTOFF LOW IN THE DESERT SOUTHWEST THIS MORNING. THE NEW WRINKLE FOR THE FORECAST IS THAT BOTH THE GFS AND ETA HAVE TRENDED THE PATH OF THE STORM BACK TO THE NORTH OVER THE PAST FEW (06Z...12Z...18Z) RUNS...BRINGING THE HEAVIEST BAND OF SNOW WITH IT. DYNAMICS FOR THE SYSTEM CONTINUE TO LOOK VERY GOOD. A COUPLED JET STRUCTURE LOOKS TO BE IN PLACE AS THE CUTOFF LOW SWINGS THROUGH MISSOURI...OPENING INTO A SHORTWAVE. LATEST SOUNDINGS HAVE COOLED JUST ENOUGH TO WARRANT ADJUSTING THE TIMING OF THE INTRODUCTION OF A RAIN/SNOW MIX...BUT ONLY BY 3 HOURS FOR THE SOUTHEASTERN HALF OF THE CWA. BY THE POST SUNRISE HOURS ANY PRECIP FALLING FROM THE SKY WILL HAVE CONVERTED TO SNOW. THE DIFFICULT PART FOR THIS FORECAST IS SNOW FALL ACCUMULATIONS AS SEVERAL VARIABLES ARE FIGHTING AGAINST EACH OTHER. ABUNDANT MOISTURE MIXED WITH THE STRONG DYNAMICS INCREASES THE POTENTIAL FOR HIGHER TOTALS. BUT...THE COLD DRY AIR ADVECTING IN BEHIND THIS SYSTEM WILL CUT INTO THE LENGTH OF PRECIP TIME...THUS PUSHING ACCUMULATIONS DOWN. GOING BACK TO THE DEEP LAYER MOISTURE...THIS WOULD WORK AGAINST ACCUMULATING SNOW AMOUNTS AS THE RATIO WILL BE MORE LIKE 1 TO 8 OR EVEN 1 TO 6. ADDITIONALLY...GROUND TEMPERATURES ARE STILL IN THE 40S DUE TO A LACK OF SUFFICIENTLY COLD TEMPERATURES. HOWEVER...SOME WEAK CSI IS EVIDENT ON THE CROSS SECTIONS FOR THE EASTERN EDGE OF THE CWA FOR LOCATIONS SOUTH OF MACON. WITH THE STRONG DYNAMICS...MOISTURE...AND SOME WEAK INSTABILITY THIS COULD MAKE FOR SOME HEAVY BANDING OF SNOW ACROSS LOCATIONS FROM BUTLER NORTHEAST THROUGH MOBERLY. THE TIMING FOR THESE HEAVIER BANDS OF SNOW LOOKS BEST FOR THE 15Z/24 TO 18Z/24 TIME PERIOD...WITH IT TAPERING OFF INTO THE AFTERNOON HOURS AS THE DEFORMATION ZONE SLIDES EAST. ALL OF THIS HAS NECESSITATED EXPANDING OUR ADVISORY NORTH. THE NEW ADVISORY AREA NOW AFFECT AREAS ALONG AND SOUTH OF A LINE RUNNING FROM HILLSDALE KANSAS...TO HIGGINSVILLE MISSOURI...TO BRUNSWICK... AND MACON. SNOW FALL ACCUMULATIONS HAVE BEEN ADJUSTED UP FOR THESE AREAS TO REFLECT ACCUMULATIONS OF 2 TO 4 INCHES. AREAS TO THE NORTH AND WEST OF THIS LINE CAN STILL EXPECT TO SEE SNOW...AND MIGHT EVEN HAVE ACCUMULATIONS OF UP TO AN INCH...BUT EXPECTATIONS ARE THAT THE MOISTURE AND BEST DYNAMICS WILL SHIFT EAST BEFORE MUCH ACCUMULATION OCCURS. THE 00Z MEDIUM RANGE MODELS SHOW SIGNIFICANT DIFFERENCES FROM YESTERDAY IN HANDLING FEATURES WITHIN THE BROAD UPPER TROUGH TO DEVELOP ACROSS THE CONUS. DID NOT WANT TO MAKE MAJOR CHANGES TO THE EXTENDED FORECAST UNTIL SOME OF THE MODEL DISCONTINUITIES ARE IRONED OUT. TEMPORARY RIDGING IS EXPECTED LATE THURSDAY INTO FRIDAY AHEAD OF THE TROUGH DEVELOPING TO THE WEST...ALLOWING FOR A SLIGHT WARMING TREND. A SHORTWAVE TROUGH IS THEN FORECAST TO BRING A SLIGHT CHANCE OF PRECIPITATION ALONG WITH THE PASSAGE OF A SURFACE FRONT ON FRIDAY. ANOTHER SHORTWAVE AND ASSOCIATED SURFACE FRONT IS TO MOVE INTO THE AREA SUNDAY...BRINGING THE CHANCE FOR RAIN WITH A POSSIBLE CHANGEOVER TO SNOW LATE SUNDAY INTO MONDAY. CUTTER/STOFLET && .PREV DISCUSSION... 308 AM TUE... CLOSED LOW OF INTEREST IS NOW STRADDLING THE ARIZONA/NEW MEXICO BORDER. MODEL AGREEMENT REGARDING THIS FEATURE AS IT PASSES ACROSS THE CENTRAL CONUS IS STILL QUITE GOOD. MODEL SOLUTIONS CONTINUE TO PROGRESS THE SURFACE LOW ACROSS SOUTHERN MISSOURI AND NORTHERN ARKANSAS ON WEDNESDAY. RAIN ASSOCIATED WITH THE WARM AIR ADVECTION REGIME SHOULD BEGIN ACROSS THE SOUTHERN CWA THIS AFTERNOON...AND GRADUALLY SPREAD NORTH TO INCLUDE AREAS ALONG A KANSAS CITY TO KIRKSVILLE LINE BY THE EVENING. DO NOT ANTICIPATE AREAS TO THE NORTH OF THE AFOREMENTIONED LINE TO RECEIVE MUCH PRECIP AT ALL...AS REFLECTED IN ONLY LOW CHANCE POPS THERE. THE BIG QUANDARY WITH THIS EVENT IS THE TIMING OF THE PRECIPITATION TRANSITION TO SNOW. AS MENTIONED BY PREVIOUS FORECASTERS...THERE IS NOT COLD AIR IN PLACE FOR THIS SYSTEM. SNOW POTENTIAL WILL ANCHOR ON THE SPEED OF DYNAMIC COOLING IN THE WESTERN QUADRANT OF THE DEFORMATION ZONE. INTERROGATION OF ETA SOUNDINGS INDICATES THAT THE CHANGE-OVER TIME WILL BE DELAYED CLOSER TO WEDNESDAY MORNING VERSUS TUESDAY NIGHT. THIS WILL LIMIT AMOUNTS...AS THE POTENTIAL PERIOD OF TIME FOR SNOWFALL WILL BE DRASTICALLY SHORTENED. FORECAST SOUNDINGS ACROSS THE NORTHWEST HALF OF THE FORECAST AREA QUICKLY DRY OUT SHORTLY AFTER THE LAYER IS ACTUALLY COLD ENOUGH FOR SNOW. THE BETTER OPPORTUNITY FOR MEASURABLE SNOWFALL APPEARS TO BE ACROSS THE SOUTHERN TIER OF EAX COUNTIES FROM LA CYGNE KANSAS TO BOONVILLE. ADEQUATE DYNAMIC COOLING IN THIS AREA SHOULD HAVE OCCURRED BEFORE THE DEFORMATION ZONE SHIFTS EAST. ALTHOUGH AM EXPECTING THAT SNOWFALL TOTALS WILL MOST LIKELY BE IN THE 1 TO 3 INCH RANGE...HAVE ISSUED A WINTER WEATHER ADVISORY FOR THIS AREA. FEEL IT IS WARRANTED...AS IT IS THE PEAK TIME OF TRAVEL FOR THE THANKSGIVING HOLIDAY...AND IS ALSO THE FIRST WINTER EVENT OF THE SEASON. IN ADDITION...IF COOLING OCCURS MORE RAPIDLY THAN EXPECTED...THE STRONG DYNAMICS (IMPRESSIVE VERTICAL VELOCITY AT 700 MB...STRONG POCKET OF 700-500MB Q VECTOR CONVERGENCE...AND A NEARLY COUPLED JET STRUCTURE) COULD EASILY CONTRIBUTE TO A HEAVY SNOW BAND SOMEWHERE ALONG THE SOUTHERN EAX BORDER. DUE TO THE SLIGHTLY SLOWER SYSTEM PROGRESSION...HAVE ALSO INCREASED POPS ON WEDNESDAY AFTERNOON. NO MAJOR CHANGES WERE MADE AFTER WEDNESDAY. SCHMIT && .EAX WATCHES/WARNINGS/ADVISORIES... KS...WINTER WEATHER ADVISORY FROM 600 AM CST WEDNESDAY UNTIL 600 PM CST WEDNESDAY FOR ZONE KSZ057...KSZ060. MO...WINTER WEATHER ADVISORY FROM 600 AM CST WEDNESDAY UNTIL 600 PM CST WEDNESDAY FOR ZONES MOZ025...MOZ032>033...MOZ038>040... MOZ043>046...MOZ053>054. $$ WFO EAX