312  
FXUS63 KTOP 300445  
AFDTOP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE TOPEKA KS  
1145 PM CDT FRI JUL 29 2016  
   
..UPDATE TO AVIATION FORECAST DISCUSSION
 
 
   
SHORT TERM
 
(THIS EVENING THROUGH SATURDAY)  
ISSUED AT 331 PM CDT FRI JUL 29 2016  
 
20Z WATER VAPOR IMAGERY SHOWS NORTHWEST FLOW PERSISTING OVER THE  
CENTRAL PLAINS AS A SHORTWAVE MOVES TOWARDS IL FROM THE MID MO RIVER  
VALLEY AND HIGH PRESSURE SITS ALONG THE AZ/UT STATE LINE. THERE DOES  
NOT APPEAR TO BE AN OBVIOUS SHORTWAVE UPSTREAM OF THE FORECAST AREAS  
THE ONLY WEAK WAVE SEEN APPEARS TO BE OVER SOUTHERN SASKATCHEWAN. AT  
THE SURFACE, WEAK SURFACE RIDGING OVER THE NORTHERN AND CENTRAL  
PLAINS IS GRADUALLY WEAKENING WITH A SURFACE TROUGH STRETCHING FROM  
THE SOUTHERN HIGH PLAINS INTO THE MID MS RIVER VALLEY.  
 
THE FORECAST FOR TODAY AND TONIGHT IS EXPECTED TO BE LARGELY DRIVEN  
BY MESOSCALE CONSIDERATIONS SINCE THERE DOES NOT APPEAR TO BE MUCH  
IN THE WAY OF LARGE SCALE FORCING. THE ISOLATED SHOWERS THAT HAVE  
POPPED UP ARE LIKELY DRIVEN BY DIURNAL HEATING SINCE IT IS LARGELY  
OCCURRING ON THE BACK SIDE OF THE SHORTWAVE. SO THIS SHOULD FALL  
APART BY SUNSET. THE MAIN UNCERTAINTY IN THE FORECAST IS WHAT  
CONVECTION OFF THE HIGHER TERRAIN OVER WY AND CO DOES. STORMS ARE  
ALREADY DEVELOPING AND IF A MCV FORMS, IT COULD CAUSE PRECIP TO  
POSSIBLY MOVE ACROSS THE AREA OVERNIGHT. MODELS PROG THE LOW LEVEL  
JET AND RETURN FLOW TO FOCUS ACROSS THE HIGH PLAINS OVERNIGHT, SO  
ANY ISENTROPIC LIFT IS EXPECTED TO BE FOCUSED TO THE WEST AS WELL.  
NEVERTHELESS MODELS CONTINUE TO SHOW SOME QPF DEVELOPING FROM  
NORTHWEST KS INTO SOUTHERN KS THROUGH THE MORNING HOURS SATURDAY.  
BECAUSE OF THIS, HAVE CONTINUED WITH SOME LOW END CHANCES POPS  
ACROSS THE SOUTHWESTERN PORTION OF THE FORECAST AREA. I WOULD EXPECT  
THE HIGH PLAINS CONVECTION HOLDING TOGETHER WITH SOME MCV FOR THIS  
TO VERIFY. SATURDAY WILL DEPEND ON WHAT HAPPENS OVERNIGHT AND  
WHETHER THERE ARE ANY BOUNDARIES OR REMNANT MID LEVEL VORTICITY IN  
THE AREA. FORECAST SOUNDINGS SHOW LITTLE OR NO INHIBITION SO IT IS  
JUST A QUESTION OF SOME LIFT OR WEAK FORCING TO SPARK SOME  
CONVECTION. AT THIS TIME HAVE BEEN CONSERVATIVE WITH THE POP  
FORECAST SINCE THE MODELS HAVE NO FORCING IMPACTING THE AREA.  
 
LOWS TONIGHT ARE FORECAST TO FALL INTO THE LOWER AND MID 60S DUE TO  
REASONABLE RADIATIONAL COOLING. WITH THE SURFACE RIDGE AXIS OVER THE  
AREA, WINDS SHOULD REMAIN LIGHT AND AS ALONG AS SKIES CLEAR OUT THE  
FORECAST SHOULD BE IN REASONABLE SHAPE. THIS BRINGS INTO QUESTION  
WHETHER THERE IS SOME GROUND FOG IN THE AREA. STORMS OUT WEST MAY  
CAST A CIRRUS SHIELD OVER THE REGION LIMITING THE FOG POTENTIAL. SO  
WITH LOW CONFIDENCE, HAVE OPTED TO NOT INCLUDE ANY MENTION OF FOG  
AND LET LATER SHIFTS MONITOR THE POTENTIAL. HIGHS SATURDAY AREA  
EXPECTED TO BE A DEGREE OR TWO WARMER THAN TODAY AS HEIGHTS RISE AND  
SOUTHERLY WINDS START TO ADVECT WARMER AIR NORTH. TEMPS IN THE MID  
TO UPPER 80S ARE EXPECTED FOR SATURDAY AFTERNOON.  
   
LONG TERM
 
(SATURDAY NIGHT THROUGH FRIDAY)  
ISSUED AT 331 PM CDT FRI JUL 29 2016  
 
LATE SATURDAY NIGHT INTO SUNDAY MORNING CONTINUE TO PRESENT THE MOST  
LIKELY WET PERIODS OF THIS FORECAST. DETAILS IN SPECIFICS REMAIN,  
AND WITH LITTLE IF ANY UPPER LEVEL SUPPORT CONFIDENCE IS NOT HIGH IN  
A WIDESPREAD RAIN, BUT ISENTROPIC UPGLIDE THROUGH MUCH OF THE MID  
TROPOSPHERE INCREASES THROUGH THE NIGHT WITH GOOD LOW LEVEL  
CONVERGENCE AS PW VALUES INCREASE TO SUPPORT HIGH CHANCE FROM  
SOUTHWEST TO NORTHEAST IN THE OVERNIGHT INTO EARLY MORNING HOURS.  
AGAIN HARD TO COMPLETELY RULE OUT A FEW STRONG TO NEAR SEVERE  
UPDRAFTS BUT SCENARIO REMAINS UNFAVORABLE FOR ANYTHING WIDESPREAD.  
COULD SEE SOME TRAINING FOR LOCALLY HEAVY RAIN AS WELL. WILL KEEP A  
SMALL POP IN THE NORTHEAST SUNDAY NIGHT WITH SOME CHANCE FOR THE  
ELEVATED BAROCLINIC ZONE TO LINGER, BUT THE WARM AND DRY AIR ALOFT  
WILL BE MOVING IN FROM THE SOUTHWEST THROUGH THE NIGHT. HAVE KEPT  
TEMPS NEAR PREVIOUS LEVELS WITH HIGHS WELL INTO THE 90S BY MONDAY  
AND APPARENT TEMPS NEAR ADVISORY LEVELS.  
 
TUESDAY THROUGH FRIDAY NIGHT TIME FRAME WILL LIKELY BE MAINLY DRY  
WITH WEAK UNORGANIZED FLOW ALOFT AND MAINLY A HIGH PRESSURE RIDGE IN  
PLACE SUGGESTING A FAIRLY STRONG EML BEING ADVECTED INTO THE AREA  
WITH GENERALLY WEAK SOUTHWEST FLOW ALOFT. THE MAIN BELT OF THE  
WESTERLIES WILL REMAIN ALONG THE NORTHERN CONUS/CANADIAN BORDER, SO  
NORTH CENTRAL AND NORTHEASTERN KANSAS WILL SEE LITTLE IN THE WAY OF  
PRECIPITATION PRODUCING SHORTWAVES WITH PERHAPS FRIDAY BEING THE  
BEST CHANCE FOR A MINOR WAVE TO BREAK DOWN THE RIDGE OVER THE  
OUTLOOK AREA. EACH MORNING LEADING UP TO THE FRIDAY TIME FRAME WILL  
STILL KEEP SLIGHT CHANCE POPS IN PLACE MAINLY NORTH OF I-70 DUE TO  
POTENTIAL MCS DEVELOPMENT AND MOVEMENT INTO PORTIONS OF SOUTH  
CENTRAL AND SOUTHEAST NEBRASKA WITH AN ISENTROPIC RESPONSE TO ANY  
POTENTIAL COLD POOLS WORKING INTO THE REGION AS A RESULT. SHOULD  
SOME PARCELS REACH THE LFC DURING THIS TIME, THERE COULD BE A FEW  
ELEVATED SHOWERS AND PERHAPS A FEW THUNDERSTORMS. IT STILL APPEARS  
THAT THIS RIDGE WILL BE WEAKER THAN THE LAST RIDGE WHICH BROUGHT A  
HEAT WAVE TO THE REGION. THAT BEING SAID THE HEAT WILL STILL BE VERY  
NOTICEABLE WITH HEAT INDICES INTO THE LOW TO MID 100S ESPECIALLY  
TUESDAY AND WEDNESDAY. OVERNIGHT LOWS FOR THE PERIOD PROBABLY HOLD  
IN THE MIDDLE 70S.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 1140 PM CDT FRI JUL 29 2016  
 
EXPECT VFR CONDITIONS THROUGH MOST OF THE NEXT 24 HOURS. THERE  
COULD BE SOME SHALLOW GROUND FOG DEVELOPING AT KTOP AROUND SUNRISE  
BUT SHOULD MIX OUT BY AFTER 13Z. IF CIRRUS CLOUD COVER MOVES IN  
THEN GROUND FOG WILL NOT DEVELOP. A FEW MODEL RUNS SHOW ISOLATED  
TO SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING AROUND THE  
TERMINALS FROM THE MID MORNING HOURS OF SATURDAY INTO THE  
AFTERNOON HOURS.  
 

 
   
TOP WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
SHORT TERM...WOLTERS  
LONG TERM...DRAKE/65  
AVIATION...GARGAN  
 
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