FXUS63 KEAX 052327
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
527 PM CST SAT DEC 5 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

MAIN THING TO FOCUS ON IN THE VERY SHORT TERM IS THE SHORT WAVE AND 
ASSOCIATED PRECIPITATION SUNDAY AFTERNOON AND SUNDAY NIGHT BEFORE 
THE BIGGER SYSTEM HANDLED IN THE MEDIUM RANGE DISCUSSION BELOW. 
MODELS CONTINUE TO AGREE ON THIS INITIAL SYSTEM RAPIDLY PROGRESSING 
FROM THE NORTHERN ROCKIES/NORTHERN GREAT BASIN RAPIDLY INTO UPPER 
MIDWEST BY SUNDAY AFTERNOON. ISENT UPGLIDE AHEAD OF THE WAVE WITH 
INITIATE PRECIP ESPECIALLY IN NW MO DURING THE MIDDAY. THE 
PRECIPITATION SHOULD INCREASE BY LATE AFTERNOON INTO THE EVENING 
HOURS OVER FAR NW MO. EXPECT THE PRECIPITATION UP THERE TO BE LIGHT 
SNOW WITH AN INCH OR TWO ACCUMULATION BY THE TIME IT ENDS BY LATE 
EVENING. AS STATED IN PREVIOUS DISCUSSIONS DRY MID LEVEL AIR MAY 
PRECLUDE ICE CRYSTAL SEEDING MEANING AN AREA OF FREEZING DRIZZLE 
MAINLY ALONG AND N OF I70. FLY IN THE OINTMENT WILL BE LOW LEVEL 
TEMPERATURES. WE MAY NOT COOL OFF FAST ENOUGH IN THE EVENING FOR THE 
PRECIP TO BE FREEZING ALONG AND NORTH OF THE I70 CORRIDOR. FURTHER 
SOUTH FROM THERE TEMPS WILL ALMOST CERTAINLY REMAIN ABOVE FREEZING 
SO ONLY LIGHT DRIZZLE EXPECTED. DONT THINK THERE WILL BE ENOUGH 
TURBULENCE IN THE LOWER LAYERS TO PRODUCE HEAVY DRIZZLE...SO EXPECT 
ANY DRIZZLE THAT DEVELOPS...FREEZING OR NOT...TO BE LIGHT.

BAILEY

MEDIUM RANGE (MON NIGHT-SAT)...

GENERALLY SPEAKING...LITTLE HAS CHANGED IN THE MEDIUM RANGE PORTIONS 
OF THE FCST REGARDING THE PENDING WINTER STORM FOR TUE AND WED.  AS 
ANTICIPATED YESTERDAY FROM ENSEMBLE PROGNOSTICATIONS...DETERMINISTIC 
GUIDANCE HAS CONVERGED ONTO A SIMILAR SYSTEM EVOLUTION THROUGH THE 
MIDDLE OF THE WEEK. PATTERN HAS TRANSITIONED NICELY TOWARDS A 
CLIMATOLOGICALLY FAVORED PROGRESSIVE UPR WAVE...A PATTERN CONDUCIVE 
TO LOCALLY HEAVY SNOWFALL. THIS MORE PROGRESSIVE WAVE MAY FEATURE 
THREE DISTINCT TRANSITIONS.  STRONG WAA AND ISENTROPIC LIFT WILL 
COMMENCE AFTER 06Z TUE AND BEGIN TO FOCUS IN PORTIONS OF NORTH 
CENTRAL KS AND NW MO AIDED WITH A BIT OF EXTRA LIFT BY A DUAL JET 
STRUCTURE ALOFT. THIS WAA PRECIP WILL RANGE WELL AHEAD OF THE UPR 
WAVE AND MAY CONTINUE FOR SOME TIME.  INITIALLY IT APPEARS SOUNDINGS 
MAY QUICKLY SATURATE AS NO STRONG EAST DRY AIR ADVECTION APPEARS 
LIKELY. SOUTH OF THIS AREA...MAY NEED TO WATCH INTRUSION OF DRY AIR 
ALOFT IN AREAS FROM CLINTON TO SEDALIA AS THESE LOCATIONS COULD BE 
CUTOFF FROM SIGNIFICANT PRECIP FOR A PERIOD IN THE DAY.  BY THE 
MIDDLE TO LATER PARTS OF TUE...AS WAA BEGINS TO SHIFT 
EAST...INCREASING DYNAMICS OF THE UPR WAVE WILL COME INTO PLAY 
ENHANCING THE MOISTURE INFLUX INTO THE CWA.  THE FINAL STAGE OF 
PRECIPITATION WILL LIKELY FALL ON THE BACKSIDE OF THE UPR WAVE AS A 
SHORT DURATION OF FRONTOGENESIS AND Q-VECTOR CONVERGENCE MAY PRODUCE 
AN INTENSE LAST BAND OF PRECIP AS COLDER AIR RUSHES IN. IT APPEARS 
THIS EVENT WILL BE STRETCHED OVER ABOUT A 12-18 HOUR WINDOW. 

DESPITE A VERY CONSISTENT UPR FLOW PATTERN...THERE WILL BE SEVERAL 
DETAILS OF THE LOWER TROPOSPHERE THAT WILL HAVE SIGNIFICANT 
IMPLICATIONS ON THE PRECIP TYPE INCLUDING BOUNDARY LAYER TEMP AND 
WARM NOSE TEMPS.  THIS BEING SAID...EXCELLENT CLUSTERING FROM THE 
GEFS ENSEMBLE MEMBERS ALONG WITH CONSISTENT LOWER PROFILE SOLNS FROM 
THE 12Z ECWMF/GFS AND TO SOME DEGREE THE GEM HAVE PRODUCED HIGHER 
THAN NORMAL CONFIDENCE THAT A PRECIP TRANSITION LINE WILL LIFT 
SOMEWHERE ALONG A KANSAS CITY TO MACON LINE BY 18-21Z TUE. FURTHER 
NORTH AND NORTHWEST...ATMOSPHERIC SOUNDINGS AND CONCEPTUAL MODELS 
INDICATE THAT COLDER AIR SHOULD REMAIN IN PLACE IN THE MID-MO VALLEY 
SUPPORTIVE OF PREDOMINATELY SNOW IN NE KS AND NW MO.  ATTM...THE 12Z 
NAM/SREF IS CONSIDERED AN OUTLIER. 

AS FAR AS THE PRECIP TRANSITION AREA...SOUNDINGS SUGGEST A RATHER 
UNIFORM WARMUP IN THE LOWER COLUMN NOT COMPLETELY SUPPORTIVE OF 
FREEZING RAIN.  HOWEVER...DO SEE A SOLN THAT COULD PLACE A MIXTURE 
OF SNOW/RAIN/SLEET FOR A SUSTAINED PERIOD IN AREAS ALONG AND SOUTH 
OF THE MO RIVER. PERHAPS A COMPLETE TRANSITION TO RAIN MAY OCCUR 
WELL SOUTH.

CONTINUING THE THEME FROM YESTERDAY...FROM A PROBABILITY STANDPOINT 
USING CURRENT DATA...INDICATIONS POINT TO THE HIGHEST PROBABILITY OF 
HEAVY SNOW (+6") TO FALL IN NORTHERN KANSAS AND NORTHERN MO IN AREAS 
ALONG AND NORTH OF HWY 36. PROBABILITIES AND SNOWFALL TOTALS ARE 
EXPECTED TO DECREASE FURTHER SOUTH INTO CENTRAL/SOUTHERN MO DUE TO 
THE PENDING UNCERTAINTY IN THE INFLUX OF WARM AIR ALOFT. AS TYPICAL 
IN THESE SYSTEMS THERE WILL LIKELY BE A SHARP CUTOFF/GRADIENT TO 
SNOWFALL WITH THE POTENTIAL FOR SOME AREAS TO RECEIVE LITTLE 
SNOWFALL. THEORETICALLY THIS ALL COULD SHIFT N OR S.
 
BEHIND THIS SYSTEM...REMAIN CONFIDENT IN A TEMPORARY INTRUSION OF 
VERY COLD TO PERHAPS ARCTIC AIR (GIVEN POTENTIAL CROSS POLAR FLOW 
SETUP AND SHIFTING OF POLAR LOW FURTHER SW).  WITH A GOOD LIKELIHOOD 
OF SNOW COVER IN NORTHERN MO BY WED NIGHT INTO THUR MORNING HAVE 
FURTHER DROPPED LOWS TO SINGLE DIGIT READINGS.  WINDS WILL ALSO BE A 
MAJOR CONCERN ON WED GIVEN THE EXPECTED DEEPER CYCLOGENESIS AT THE 
SFC.  THIS BEING SAID WILL INTRODUCE BLOWING SNOW WORDING TO AREAS 
WHICH MAY RECEIVE THE HIGHEST SNOW.

DUX

&&

.AVIATION...

FOR THE 00Z TAFS...EXPECT AN OVERALL INCREASE IN HIGH CLOUD COVER 
STEADILY LOWERING FROM 20KFT TO 10KFT OVER THE 24 HOUR PERIOD AHEAD 
OF AN ADVANCING SHORTWAVE TROUGH. WEAK SURFACE WAVE EXPECTED TO RIDE 
UP AN INVERTED SURFACE TROUGH JUST WEST OF THE TERMINALS LATE IN THE 
PERIOD WHICH SHOULD ALLOW SOUTHERLY WINDS TO GRADUALLY BACK TOWARD 
THE EAST-SOUTHEAST BY 00Z MONDAY. SPEEDS SHOULD AVERAGE AT OR BELOW 
8 KNOTS.

BOOKBINDER

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$