601  
FXUS63 KEAX 142333  
AFDEAX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO  
533 PM CST THU DEC 14 2017  
   
DISCUSSION
 
 
ISSUED AT 305 PM CST THU DEC 14 2017  
 
WATER VAPOR IMAGERY WITH 1.5PVU PRESSURES OVERLAID SHOWS A FAST  
MOVING CLIPPER SYSTEM DIVING SOUTHEAST THROUGH THE CENTRAL PLAINS.  
REGIONAL RADAR IMAGERY AND SURFACE OBSERVATIONS SHOW A BROAD AREA OF  
LIGHT PRECIPITATION, LIGHT RAIN AND SOME LIGHT SNOW AT TIMES, MOVING  
INTO NORTH CENTRAL KS. MODELS SHOW THE UPPER WAVE WEAKENING AS IT  
MOVES INTO THE FORECAST AREA AND BECOMING MORE STRUNG OUT AND NOT AS  
CONCENTRATED. THIS RESULTS IN THE LIGHT QPF MODELS SHOW IN NE AND  
KS, EVAPORATING AS IT TRACKS EAST. THIS TREND CAN BE OBSERVED ON  
THE LATEST RADAR IMAGERY WITH THE EASTERN MOST ECHOS DECREASING/  
DRYING UP. GIVEN THIS FEEL THAT THERE IS A SMALL CHANCE FOR SOME  
LINGERING FLURRIES AND/OR SPRINKLES TO MOVE INTO WESTERN PORTIONS  
OF THE FORECAST AREA LATE THIS AFTERNOON AND THIS EVENING. SOME OF  
THIS MAY TRANSITION EAST AS THE STRUNG OUT UPPER TROUGH MOVES  
OVER THE AREA.  
 
THE NEXT SYSTEM, WHICH WILL BRING MUCH BETTER CHANCES FOR MEASURABLE  
PRECIPITATION, WILL MOVE INTO THE AREA SUNDAY MORNING. WITH THE  
WESTERN UPPER RIDGE HAVING RETROGRADED WEST, OFF THE WEST COAST,  
A DEEP TROUGH WILL DEVELOP OVER THE SOUTHWEST. THIS WILL HELP  
ADVECT BETTER MOISTURE NORTHWARD. EVEN WITH THIS BETTER  
PRECIPITATION SCENARIO, THE NORTHWARD EXTENT OF PRECIPITATION  
REMAINS UNCERTAIN. BUT MODELS ARE IN GOOD AGREEMENT BRINGING LIGHT  
RAIN INTO SOUTHERN PORTIONS OF THE FORECAST AREA SO HAVE PLACED  
THE HIGHEST POPS IN OUR SOUTH AND SOUTHEAST. THERE WILL LIKELY BE  
A RELATIVELY SHARP GRADIENT TO THE NORTHWARD EXTENT OF THE  
PRECIPITATION DUE TO DRIER AIR FILTERING INTO THE REGION FROM THE  
NORTH. FOR NOW MODELS RANGE FROM DRY TO NORTHWEST MO GETTING 0.1"  
TO 0.2" OF RAIN. THIS HIGHER QPF IS AN OUTLIER AND IS WHAT'S  
LEADING TO HIGHER POPS IN OUR NORTHERN AND NORTHWESTERN ZONES. FOR  
NOW HAVE ONLY MADE MINOR TWEAKS TO SCALE BACK POPS IN THIS AREA.  
IT'S LIKELY AS THE SUNDAY TIME FRAME APPROACHES, A TIGHTENING OF  
POPS IN THE NORTHWARD EXTENT OF THE PRECIPITATION WILL CONTINUE.  
 
THE REMAINDER OF THE FORECAST LOOKS DRY AT THIS POINT AS WE RETURN  
TO MORE OF A NORTHWESTERLY FLOW. FOR THE LATER HALF OF NEXT WEEK,  
MODELS SHOW THE PATTERN BECOMING MORE AMPLIFIED. BUT THERE IS  
SUBSTANTIAL DIFFERENCES IN HOW DEEP AND HOW PROGRESSIVE A TROUGH  
MOVING ACROSS THE MIDDLE OF THE COUNTRY IS. THE ECMWF AND THE  
CANADIAN ARE IN DECENT AGREEMENT WITH THE UPPER PATTERN. THE GFS,  
WHILE IT LAGS THE TROUGH IN THE UPPER MIDWEST, IT DIGS A DEEP LOW  
OVER THE BAJA AND SOUTHERN CALIFORNIA AND ARIZONA. EVEN WITH THESE  
DIFFERENCES IN THE UPPER PATTERN, ALL THREE MODELS SHOW A VERY  
STRONG COLD FRONT MOVING THROUGH THE FORECAST AREA NEXT THURSDAY.  
WITH THE CONSIDERABLE DIFFERENCES IN THE UPPER PATTERN, THERE IS  
QUITE A BIT OF VARIABILITY IN THE TRACK OF THE SURFACE LOW AND WHERE  
PRECIPITATION MAY FALL. BUT THERE ARE INDICATIONS THAT WINTRY  
PRECIPITATION WILL IMPACT THE MIDDLE OF THE COUNTRY LEADING INTO A  
BUSY HOLIDAY TRAVEL WEEKEND.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)  
ISSUED AT 524 PM CST THU DEC 14 2017  
 
ALTHOUGH VFR CEILINGS ARE PREVAILING FOR THE START OF THIS TAF  
PERIOD, MVFR CEILINGS ARE ANTICIPATED TO OVERTAKE THE TERMINALS BY  
THE PRE-DAWN HOURS ON FRIDAY. THESE CONDITIONS ARE EXPECTED TO  
ONLY LAST THROUGH JUST AFTER DAWN, WITH PARTIALLY CLEARING SKIES  
BY MIDDAY FRIDAY. LOOK FOR LIGHT NW WINDS TONIGHT TO BECOME MORE  
WESTERLY TOMORROW.  
 

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

 
 

 
 
DISCUSSION...CDB  
AVIATION...LG  
 
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