868  
FXUS64 KOUN 172337 AAA  
AFDOUN  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE NORMAN OK  
637 PM CDT THU AUG 17 2017  
   
AVIATION
 
 
18/00Z TAFS. VFR CONDITIONS WILL BE FORECAST THROUGH PERIOD  
OUTSIDE OF POTENTIAL RESTRICTIONS WITH TSRA IN THE 6-12Z TIMEFRAME  
ACROSS NORTHERN OKLAHOMA TERMINALS. ADDITIONAL TSRA POSSIBLE LATE  
TOMORROW BUT CONFIDENCE TOO LOW FOR PLACEMENT ATTM.  
 

 
   
PREV DISCUSSION
 
/ISSUED 338 PM CDT THU AUG 17 2017/  
 
DISCUSSION...  
SUBSIDENCE BEHIND EASTWARD MOVING SHORTWAVE TROUGH OVER THE GREAT  
LAKES AND IN THE WAKE OF MCS HAS RESULTED IN MOSTLY CLEAR SKIES  
ACROSS THE AREA THIS AFTERNOON. SOME DIURNAL CUMULUS DEVELOPMENT  
HAS BEEN NOTED WHERE LOW LEVEL MOISTURE REMAINS HIGHEST, MAINLY  
ACROSS SOUTH-CENTRAL AND SOUTHEAST OKLAHOMA. MORE EXTENSIVE  
VERTICAL GROWTH OF CUMULUS AND CONVECTIVE DEVELOPMENT SHOULD BE  
CONFINED TO JUST SOUTH OF OUR FORECAST AREA.  
 
STRENGTHENING MOIST SOUTHERLY FLOW OVER THE HIGH PLAINS SHOULD  
SUPPORT SOME DIURNAL SURFACE BASED CONVECTIVE DEVELOPMENT LATER  
TODAY WHERE 0-2 KM STREAM LINES ARE SLIGHTLY CONVERGENT AND NEAR  
THE RATON MESA. THIS WOULD THEN MOVE EASTWARD WITH MEAN FLOW AND  
POSSIBLY GROW UP SCALE SLIGHTLY POTENTIALLY REACHING OUR NORTHWEST  
COUNTIES LATE THIS EVENING AND PROGRESSING EASTWARD IN A WEAKENED  
STATE OVERNIGHT. MODELS SHOW A THIN LAYER OF ENHANCED MID-LEVEL  
MOISTURE ON THE 315K SURFACE. MODELS CAN SOMETIMES STRUGGLE WITH  
DEPICTING THE DETAILS OF MOISTURE IN THESE SCENARIOS AND THIS IS  
THE MAIN SOURCE OF UNCERTAINTY IN THE OVERNIGHT FORECAST. IF MID-  
LEVEL MOISTURE IS AS EXTENSIVE OR MORE EXTENSIVE THAN SHORT TERM  
GUIDANCE SUGGESTS, THIS WOULD CONTRIBUTE TO AT LEAST WEAK MUCAPE  
AND SUPPORT ELEVATED CONVECTION THROUGH TOMORROW MORNING,  
PRIMARILY OVER THE NORTHERN HALF OF THE FORECAST AREA.  
 
CURRENT THINKING IS THAT OVERNIGHT AND EARLY MORNING CONVECTION  
SHOULDN'T BE AS DELETERIOUS TO LATER AFTERNOON POTENTIAL AS SOME  
OF THE RECENT MORE INTENSE MCSS. LATER IN THE AFTERNOON, MODERATE  
TO STRONG INSTABILITY SHOULD DEVELOP NEAR A WEAK COLD FRONT ACROSS  
NORTHWEST OKLAHOMA. MID-LEVEL HEIGHT RISES MAY WORK AGAINST  
CONVECTIVE DEVELOPMENT, BUT GIVEN THE DEGREE OF DIABATIC  
HEATING/DESTABILIZATION, ISOLATED TO SCATTERED THUNDERSTORM SHOULD  
FORM WITHIN THIS ZONE OF CONVERGENCE. DEEP LAYER SHEAR SHOULD BE  
MARGINALLY SUPPORTIVE OF STORM ORGANIZATION AND SOME WIND/HAIL  
POTENTIAL. SOME CONSOLIDATION AND INCREASE IN COVERAGE MAY OCCUR  
THROUGH LATE EVENING AS STORMS MOVE EASTWARD POTENTIALLY LASTING  
INTO THE NIGHT.  
 
A DRIER PATTERN SHOULD DEVELOP THIS WEEKEND INTO NEXT WEEK AS MEAN  
RIDGING BUILDS SLIGHTLY. WE'LL NEED TO WATCH BOUNDARY LAYER  
MOISTURE CHARACTERISTICS. IF MODELS ARE UNDER FORECASTING LOW  
LEVEL MOISTURE SLIGHTLY, ISOLATED DIURNAL CONVECTIVE DEVELOPMENT  
MAY BECOME MORE LIKELY. OTHERWISE, THERE MAY BE A PERIOD OF WEAK  
SYNOPTIC SCALE FORCING TO AID IN CONVECTIVE DEVELOPMENT LATE  
TUESDAY AND TUESDAY NIGHT.  
 
BRB  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
OKLAHOMA CITY OK 70 91 73 94 / 10 30 40 10  
HOBART OK 72 95 74 96 / 20 20 30 10  
WICHITA FALLS TX 73 94 74 96 / 10 10 20 10  
GAGE OK 68 93 69 94 / 30 40 40 10  
PONCA CITY OK 69 91 70 92 / 20 30 40 10  
DURANT OK 72 92 74 95 / 10 20 30 20  
 

 
   
OUN WATCHES/WARNINGS/ADVISORIES
 
 
OK...NONE.  
TX...NONE.  

 
 

 
 
17/11/11  
 
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