775  
FXUS63 KTOP 191144  
AFDTOP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TOPEKA KS  
544 AM CST SUN FEB 19 2017  
   
..UPDATE TO AVIATION FORECAST DISCUSSION
 
 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 349 AM CST SUN FEB 19 2017  
 
SOUTHERLY LOW LEVEL FLOW BRINGING INCREASED MOISTURE INTO THE AREA  
OVERNIGHT. ENOUGH CLEARING AND WEAKER WINDS ABOVE THE BOUNDARY LAYER  
IN THE SOUTHEAST TO ALLOW SOME FOG TO FORM. CALLS TO LAW ENFORCEMENT  
IN THIS AREA REVEAL FOG IS PATCHY AND SOME VARIATION OF OBSERVATION  
VISIBILITIES SUPPORTS THIS. WILL WATCH TRENDS BUT AT THIS TIME WILL  
HOLD OFF ON DENSE FOG ADVISORY. HIGH CLOUD BECOMING MORE PERSIST  
INTO WESTERN AND CENTRAL KANSAS AHEAD OF SOUTHERN STREAM UPPER LOW.  
 
HIGH CLOUD SHOULD CONTINUE ON EAST THIS MORNING WITH LOW LEVELS  
CONTINUING TO SATURATE AS WELL. WITH SOUTHERLY FLOW ALSO PICKING UP,  
THIS MAKES FOR A TOUGH HIGH TEMPERATURE FORECAST. MODELS HAVE BEEN  
CONSISTENTLY TOO COOL IN RECENT DAYS, BUT EVEN THE RAP IS KEEPING  
DIURNAL RISES IN CHECK IN THIS MORE MOIST REGIME. HAVE STAYED CLOSER  
TO IT FOR HIGHS. EXPECT MORNING FOG TO SLOWLY DISSIPATE WITH THE  
STRONGER WINDS DEVELOPING OVER THE BOUNDARY LAYER BUT WILL KEEP SOME  
MENTION INTO THE LATE MORNING. PRECIP CHANCES INCREASE THIS EVENING  
AS THE UPPER LOW WEAKENS AS IT ENTERS THE SOUTHERN PLAINS. MODELS  
CONTINUE TO HAVE A DECENT SPREAD IN WHERE BEST FORCING FOR ASCENT  
WILL BE AS A NORTHERN BRANCH WAVE ENTERS THE NORTHERN PLAINS NEARLY  
COINCIDENT WITH THE SOUTHERN WAVE. PW VALUES THAT WERE ALREADY 50%  
ABOVE NORMAL SATURDAY EVENING NEARLY TRIPLE BY 12Z MONDAY PER EVERY  
GEFS ENSEMBLE MEMBER AND WILL BE NEAR RECORD HIGH VALUES. EXPECT AT  
LEAST SCATTERED SHOWERS AND A FEW THUNDERSTORMS FOR EASTERN AREAS BY  
LATE IN THE NIGHT DESPITE WEAK FORCING BUT ANY SIGNIFICANT AMOUNTS  
LOOK UNLIKELY.  
   
LONG TERM
 
(MONDAY THROUGH SATURDAY)  
ISSUED AT 349 AM CST SUN FEB 19 2017  
 
ON WASHINGTONS BIRTHDAY,MONDAY,THE UPPER TROUGH WILL MOVE THROUGH  
EASTERN BY EARLY EVENING. ASSOCIATED COLD FRONT IS FORECAST TO MOVE  
THROUGH MUCH OF NORTHEAST KANSAS BY 00Z TUESDAY. MODELS SHOW A FEW  
HUNDRED JULES OF MUCAPE IN THE MORNING IN NORTHEAST AND EAST CENTRAL  
KANSAS AND WILL CONTINUE TO MENTION A SLIGHT CHANCE OF  
THUNDERSTORMS. BY AFTERNOON, THE DEEPER MOISTURE WILL ADVECT  
EASTWARD INTO MISSOURI AS WINDS SHIFT TO THE SOUTHWEST AND WEST  
WHILE THE FORCING FOR ASCENT SHIFTS EAST AS WELL. CONTINUED TREND OF  
DRYING OUT THE CWA FROM WEST TO EAST IN THE AFTERNOON HOURS. NOT  
MUCH IN THE WAY OF COOLER TEMPERATURES IN THE WAKE OF THE FRONTAL  
BOUNDARY. ON TUESDAY, WESTERLY DOWNSLOPE WINDS WILL DEVELOP ACROSS  
KANSAS AND NEBRASKA. FORECAST SOUNDINGS SHOW MIXING DOWN FROM 900MB-  
850MB IN THE AFTERNOON WITH 850 MB TEMPERATURES AVERAGING AROUND 13  
CELSIUS AND SHOULD YIELD TEMPERATURES IN THE MID TO UPPER 70S.  
TUESDAY THROUGH EARLY THURSDAY IS LOOKING DRY AND MILD WITH NEARLY  
ZONAL FLOW ALOFT. TEMPERATURES WILL CONTINUE TO BE ABOVE NORMAL WITH  
HIGHS IN THE MID 70S ON WEDNESDAY. ON THURSDAY AN UPPER TROUGH WILL  
MOVE ACROSS THE ROCKIES AND INTO THE WESTERN HIGH PLAINS. MODELS ARE  
BEGINNING TO COME INTO A LITTLE MORE AGREEMENT WITH THE NEW  
OPERATIONAL GFS TRENDING TOWARD THE ECMWF AND THE CMC SOLUTIONS.  
THIS SYSTEM LOOKS TO BRING A CHANCE OF RAIN AND THUNDERSTORMS  
INITIALLY THURSDAY AFTERNOON AND EVENING. COLDER AIR ON THE NORTH  
SIDE OF THE SURFACE LOW WILL ALLOW PRECIPITATION TO CHANGE OVER TO A  
RAIN AND SNOW MIX THEN EVENTUALLY OVER TO ALL SNOW FOR MUCH OF NORTH  
CENTRAL KANSAS THURSDAY NIGHT. THERMAL PROFILES SHOW A CHANGE BACK  
TO ALL RAIN ON FRIDAY BEFORE THE SYSTEM MOVES OUT. TEMPERATURES ON  
FRIDAY WILL BE MUCH COLDER WITH HIGHS IN THE UPPER 30S TO LOWER 50S  
WITH THE COLDER TEMPERATURES IN NORTH CENTRAL KANSAS. CHANGES IN  
TRACK AND SPEED ARE LIKELY YET, SO KEEP ABREAST OF LATER FORECASTS.  
NEXT SATURDAY WILL START OUT IN THE 20S FOR LOWS WARMING INTO THE  
40S IN THE AFTERNOON. DRY WEATHER IS EXPECTED ON SATURDAY IN THE  
ABSENCE OF ANY WEATHER SYSTEMS.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 544 AM CST SUN FEB 19 2017  
 
TIMING OF LIMITING CONDITIONS IS THE MAIN CHALLENGE THIS CYCLE.  
MOST PERSISTENT FOG HAS REMAINED TO THE SOUTH OF THE TERMINALS BUT  
COULD SEE THIS BECOME MORE PREVALENT IN THE NEXT FEW HOURS. SHOULD  
SEE SLOW IMPROVEMENTS THROUGH 19Z BUT DOWNWARD TRENDS COME AGAIN  
BY 04Z AS MOISTURE DEEPENS WITH IFR ANTICIPATED BY THE END OF THIS  
FORECAST.  
 

 
   
TOP WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...65  
LONG TERM...53  
AVIATION...65  
 
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