410  
FXUS66 KPDT 160258  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
758 PM PDT MON OCT 15 2018  
   
UPDATE
 
CLEAR SKIES AND LIGHT WINDS ARE EXPECTED TO PERSIST  
THROUGH TONIGHT AND TUESDAY. PATCHY FOG POSSIBLE NEAR RIVERS.  
CURRENT FORECAST ON TRACK. COONFIELD  
 

 
   
AVIATION...06Z TAFS
 
MOSTLY CLEAR SKIES WITH WINDS LESS THAN  
10 KT THROUGH THE NEXT 24 HOURS. PATCHY BR POSSIBLE NEAR THE KPSC  
AFTER 10Z BUT MINIMAL IMPACTS. 76  
 

 
   
PREV DISCUSSION
 
/ISSUED 219 PM PDT MON OCT 15 2018/  
 
SHORT TERM...TONIGHT THROUGH THURSDAY..AN UPPER LEVEL RIDGE OF  
HIGH PRESSURE CENTERED OFF THE COAST WILL CONTINUE TO SHIFT  
INLAND AND SETTLE OVER THE PACIFIC NORTHWEST. THIS WILL STRENGTHEN  
AND LOWER THE SUBSIDENCE INVERSION ASSOCIATED WITH THE HIGH  
PRESSURE. THIS WILL RESULT IN MORE WARMING IN THE HIGHER  
ELEVATIONS THAN AT THE LOW ELEVATIONS THROUGH TUESDAY AS SOME  
COOL AIR REMAINS TRAPPED BENEATH THE INVERSION. TEMPS WILL CLIMB A  
FEW DEGREES EACH DAY WITH VALLEY HIGHS IN THE 60S TO LOW 70S.  
NIGHTTIME LOWS IN THE UPPER 20S/LOWER 30S IN THE MOUNTAINS TO  
UPPER 30S/LOWER 40S IN THE VALLEYS.THERE COULD BE SOME SPOTS OF  
FOG DEVELOPING UNDER THIS PATTERN BUT MAINLY NEAR OR AROUND LARGE  
BODIES OF WATER LIKE LAKES AND RIVERS OR IN SMALL MOUNTAIN  
VALLEYS. WINDS WILL BE VERY LIGHT THROUGH THE SHORT TERM PERIOD,  
ALONG WITH DRY CONDITIONS UNDER MOSTLY CLEAR SKIES.  
 
LONG TERM...THURSDAY NIGHT THROUGH MONDAY...UPPER LEVEL RIDGE  
LOOKS TO REMAIN IN CONTROL THROUGH AT LEAST SUNDAY WITH MOSTLY  
CLEAR SKIES, LIGHT WINDS, MILD DAYTIME HIGHS AND CHILLY OVERNIGHT  
LOWS. WITH HIGH PRESSURE EXPECTED TO REMAIN OVERHEAD WE WILL SEE  
AN INCREASINGLY STAGNANT AIRMASS WITH STRONG SUBSIDENCE INVERSIONS  
KEEPING AFTERNOON MIXING HEIGHTS FOR THE LOWER ELEVATIONS LESS  
THAN 2000 FEET. AS POLLUTANT AND MOISTURE LEVELS UNDER THE  
INVERSION CONTINUE TO BUILD SHOULD SEE AN INCREASE IN MORNING  
PATCHY FOG COVERAGE ESPECIALLY SATURDAY AND SUNDAY WITH THE RIDGE  
AXIS DIRECTLY OVERHEAD, BUT OVERALL COVERAGE AND DURATION WILL BE  
LIMITED BY A COMBINATION OF DRY/WARM GROUND CONDITIONS AND STILL  
REASONABLE MID OCTOBER SUN ANGLES. HAVE KEPT ANY MENTION OF HAZE  
OUT OF THE FORECAST FOR NOW, AS SIGNIFICANT VISIBILITY REDUCTIONS  
IN HAZE WILL BE LARGELY DRIVEN BY LOCAL BURN DECISIONS. THERE ARE  
SOME TIMING DIFFERENCES IN THE MODELS REGARDING THE EVENTUAL SHIFT  
OF THE RIDGE TO THE EAST WITH A RETURN TO A MORE ACTIVE PATTERN,  
GIVEN THE SPREAD IN SOLUTIONS FROM MONDAY AFTERNOON TO WEDNESDAY  
HAVE KEPT THE FORECAST DRY FOR NOW THROUGH TUESDAY MORNING. PECK  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 35 61 36 62 / 0 0 0 0  
ALW 37 64 39 64 / 0 0 0 0  
PSC 35 66 36 66 / 0 0 0 0  
YKM 36 66 36 67 / 0 0 0 0  
HRI 34 66 36 66 / 0 0 0 0  
ELN 33 65 36 67 / 0 0 0 0  
RDM 27 68 30 70 / 0 0 0 0  
LGD 33 65 36 68 / 0 0 0 0  
GCD 34 67 37 69 / 0 0 0 0  
DLS 37 67 38 69 / 0 0 0 0  
 

 
   
PDT WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  

 
 

 
 
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