105  
FXUS63 KTOP 190750  
AFDTOP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TOPEKA KS  
250 AM CDT SAT AUG 19 2017  
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 250 AM CDT SAT AUG 19 2017  
 
THE WEAK SURFACE TROUGH THAT WAS MOVING THROUGH THE AREA YESTERDAY  
HAS BECOME RATHER DIFFUSE, AND IS EXPECTED TO LIFT NORTHWARD TODAY.  
LIGHT TO CALM SURFACE WINDS AND CLEAR SKIES IS SUPPORTING DECENT  
RADIATIONAL COOLING. THEREFORE GROUND FOG DEVELOPMENT IS POSSIBLE  
BETWEEN NOW AND SUNRISE ESPECIALLY IN THE LOW LYING AREAS. TODAY  
SKIES REMAIN MOSTLY SUNNY AND WINDS RELATIVELY LIGHT WITH HIGHS IN  
THE 90S. THESE TEMPERATURES IN COMBINATION WITH DEW POINTS IN THE  
60S WILL CAUSE HEAT INDICES TO REACH THE MID TO UPPER 90S THIS  
AFTERNOON. LATER TODAY STORMS ARE EXPECTED TO DEVELOP ALONG THE  
DEEPER SURFACE TROUGH OR DRY LINE ACROSS NORTHWEST KS AND WESTERN  
NE. THE ARE INDICATIONS THAT THESE STORMS CLUSTERS COULD FORM INTO  
AN FORWARD PROPAGATING MCS. THE MODELS ARE INDICATING A VERY SUBTLE  
SHORTWAVE THAT LIFTS OUT OF WY, WHICH COULD SUPPORT THIS SCENARIO AS  
WELL AS AMPLE LOW LEVEL MOISTURE AND A LOW LEVEL JET. ALTHOUGH THE  
MODELS DIFFER ON THE EXACT LOCATION AND COVERAGE OF THE POSSIBLE  
CONVECTION LATER THIS EVENING, BUT THE CONSENSUS OF THE LATEST  
GUIDANCE IS TRACKING A POSSIBLE MCS NEAR THE KS/NE STATE LINE. AS  
TYPICAL WITH THESE SYSTEMS STRONG TO SEVERE WIND GUSTS WILL BE  
POSSIBLE IF THIS MCS CAN MATERIALIZE AND MAINTAIN STRENGTH AS IT  
PROGRESSES EAST-SOUTHEASTWARD THROUGH THE LATE EVENING AND EARLY  
MORNING. THERE IS SOME AGREEMENT BETWEEN THE HRRR AND WRF ENSEMBLES  
WITH TRACKING SOMETHING INTO NORTH CENTRAL KS, WHILE THE NAM  
SLIGHTLY FURTHER NORTH. A FEW OF THE HRRR ENSEMBLES EVEN BRING THE  
MCS INTO PORTIONS OF EASTERN KS. BOTH THE EC AND GFS DO NOT SHOW  
MUCH CONVECTION AFTER MIDNIGHT LET ALONE ANYTHING REACHING OUR AREA  
WITH THE EXCEPTION OF FAR NORTH CENTRAL KS.  
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 250 AM CDT SAT AUG 19 2017  
 
WILL KEEP SMALL PRECIP CHANCES GOING FOR MUCH OF SUNDAY WITH SOME  
POTENTIAL FOR OVERNIGHT CONVECTION TO LINGER. SOUTHERLY WINDS BRING  
DEWPOINTS ABOVE 70 IN THE EASTERN COUNTIES WITH LITTLE INHIBITION  
FOR AFTERNOON STORMS. DEEP SHEAR LOOKS LIMITED BUT COULD SEE A  
STRONG STORM OR TWO GIVEN ML CAPE ABOVE 3000 J/KG. THIS MOISTURE  
WILL CONTRIBUTE TO HEAT INDEX VALUES PEAKING AROUND 100 FOR THE  
BULK OF THE AREA. WILL KEEP SMALL PRECIP CHANCES GOING INTO THE  
NIGHT WITH DEEP MOISTURE INCREASING FROM THE SOUTHWEST.  
 
NOT MUCH CHANGE IN THINKING FOR MONDAY'S FORECAST. MODELS ARE  
CONSISTENT WITH A WEAK WAVE OVER THE GULF OF CALIFORNIA THIS  
MORNING MEANDERING INTO THE STATE LATE SUNDAY NIGHT INTO MONDAY  
WITH SIGNIFICANT MID AND UPPER MOISTURE. THESE FEATURES KEEP A  
CHANCE FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST. HAVE  
INCREASED CLOUD COVER SOMEWHAT, IN KIND WITH MOST MODEL GUIDANCE,  
BUT THERE REMAINS SOME OPPORTUNITY FOR BREAKS IN THE CLOUD  
COVER. HIGH TEMPS MAY BACK OFF A BIT IN THE INCREASED CLOUD BUT  
APPARENT TEMPS WILL STILL REACH THE 90S TO AROUND 100.  
 
BEST PRECIP CHANCES COME LATE MONDAY NIGHT INTO TUESDAY AS A  
STRONGER COLD FRONT PASSES THROUGH. TIMING OF THIS FEATURE KEEPS  
SEVERE WEATHER CONCERNS LIMITED. A MODIFIED SOUTHERN CANADIAN  
AIRMASS IN PLACE FOR TUESDAY NIGHT THROUGH FRIDAY KEEPS THESE  
PERIODS MAINLY DRY.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1142 PM CDT FRI AUG 18 2017  
 
EXPECT VFR CONDITONS FOR MOST OF THE NEXT 24 HOURS AT ALL THE  
TERMINAL SITES. THERE IS A CHANCE THAT SOME SHALLOW GROUND FOG MAY  
DEVELOP AT KTOP AND KMHK BY 11Z BUT SHOULD MIX OUT SHORTLY AFTER  
SUNRISE.  
 

 
   
TOP WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...SANDERS  
LONG TERM...65  
AVIATION...GARGAN  
 
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