497  
FXUS66 KPDT 210527 AAA  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
1030 PM PDT FRI SEP 20 2019  
 
UPDATED THE AVIATION DISCUSSION  
   
UPDATE
 
THE LATEST RADAR WAS SHOWING A FEW SHOWERS THAT MAY MOVE  
INTO THE NORTHEAST SECTIONS OF THE REGION SUCH AS OUR NORTHERN  
BLUES AND WALLOWAS. THE SHOWERS WERE ASSOCIATED WITH A WEAK  
DISTURBANCE THAT IS FORECAST TO CLIP OUR NE CWA OVERNIGHT.  
ELSEWHERE THE REGION SHOULD REMAIN DRY AS TEMPERATURES FALL INTO  
THE 50S WITH 40S IN THE HIGHER ELEVATIONS. MINOR CHANGES WERE DONE  
TO POPS AND TEMPS AND SKY AND NOW THE SHORT TERM FORECAST APPEARS  
ON TRACK.  
   
AVIATION
 
MID AND HIGH LEVELS CLOUDS ARE LIKELY WHILE VFR  
CONDITIONS WILL PERSIST AT ALL TAF SITES FOR THE NEXT 24 HOURS.  
 

 
   
PREV DISCUSSION
 
/ISSUED 137 PM PDT FRI SEP 20 2019/  
 
SHORT TERM...REST OF TODAY THROUGH MONDAY...NORTHERLY FLOW  
CONTINUES TO RESULT IN A FEW UPSLOPE SHOWERS OVER THE  
BLUE/WALLOWA MOUNTAINS. EXPECT COVERAGE TO CONTINUE TO DECREASE  
THROUGH THE EVENING BEFORE ENDING OVERNIGHT. UPPER LEVEL RIDGE  
WILL SET UP OVERHEAD FOR SATURDAY WITH PARTLY CLOUDY SKIES AND  
TEMPERATURES WARMING INTO THE MIDDLE TO UPPER 70S ACROSS THE  
COLUMBIA BASIN WITH 60S FOR THE MOUNTAINS. NEXT SYSTEM ARRIVES  
SUNDAY WITH SHOWERS ARRIVING ALONG THE CASCADES NEAR DAWN THEN  
GRADUALLY SPREADING EAST THROUGH THE FORECAST AREA BY THE EARLY  
AFTERNOON. RAIN AMOUNTS WILL BE HIGHEST IN THE MOUNTAINS RANGING  
FROM 0.1-0.3" WITH AMOUNTS OF ONLY A FEW HUNDRETHS OF AN INCH  
EXPECTED ACROSS THE COLUMBIA BASIN. ANY LINGERING SHOWERS  
ASSOCIATED WITH THE FRONTAL BOUNDARY END BEFORE SUNRISE MONDAY  
WITH A MORE WESTERLY, MAINLY DRY, FLOW PATTERN SETTING UP FOR  
EARLY NEXT WEEK. RICHARDS  
 
LONG TERM...MONDAY NIGHT THROUGH FRIDAY...MODELS IN FAIRLY GOOD  
AGREEMENT THROUGH MID-WEEK. SHORT-WAVE RIDGING SHIFTS SOUTH AND EAST  
MONDAY NIGHT AS THE REGION FALLS UNDER FAST NORTHWEST FLOW ALOFT.  
EXPECT DRIER CONDITIONS THROUGH MID-WEEK. HOWEVER THERE WILL BE  
VARIABLE CLOUD COVER AND POSSIBLE MOUNTAIN SHOWERS, ESPECIALLY OVER  
THE WA CASCADES, AS PACIFIC MOISTURE AND A COUPLE OF QUICK MOVING  
FRONTS TRY TO CLIP THE REGION. MODELS DIFFER A BIT FOR LATE WEEK,  
BUT THERE IS INCREASING CONFIDENCE FOR A STRONG COLD FRONT TO SWING  
THROUGH ON WEDNESDAY NIGHT OR THURSDAY, FOLLOWED BY A DEEPENING  
UPPER-LEVEL LOW DROPPING SOUTH AND SETTING UP OVER THE WESTERN US  
THURSDAY NIGHT INTO FRIDAY. EXPECT A GOOD CHANCE OF SHOWERS FOR THE  
REGION, BUT OVERALL MODEL SPREAD AND RUN-TO-RUN VARIABILITY IN THE  
UPPER-LOW STRENGTH, TIMING AND LOCATION MAKE IT DIFFICULT TO NAIL  
DOWN ANY HIGH END PROBABILITIES NEARLY A WEEK OUT. MOUNTAIN SNOW A  
STRONG POSSIBILITY FOR LATE WEEK AS FREEZING LEVELS EXPECTED TO DROP  
SIGNIFICANTLY. SOME BREEZY TO WINDY CONDITIONS POSSIBLE AS STRONGER  
WINDS ALOFT MIX DOWN WITH EACH FRONTAL PASSAGES, ESPECIALLY TUESDAY.  
SEASONAL TEMPS EXPECTED THROUGH MID-WEEK WITH HIGHS IN THE 60S TO  
MID 70S. WELL BELOW NORMAL TEMPS EXPECTED THURSDAY AND FRIDAY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 49 74 50 72 / 0 0 0 30  
ALW 53 76 54 76 / 10 0 0 30  
PSC 54 78 54 76 / 0 0 0 30  
YKM 48 76 49 71 / 0 0 0 50  
HRI 52 78 52 75 / 0 0 0 30  
ELN 49 75 50 69 / 0 0 0 60  
RDM 42 73 45 67 / 0 0 0 60  
LGD 44 70 47 72 / 10 0 0 40  
GCD 44 71 47 71 / 10 0 0 40  
DLS 54 76 55 71 / 0 0 0 60  
 

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

 
 

 
 
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