079  
FXUS66 KPDT 280507  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
1010 PM PDT WED OCT 27 2021  
 
UPDATED AVIATION DISCUSSION  
   
SHORT TERM
 
A BAND OF PRECIPITATION EXTENDS ACROSS THE SOUTHERN  
HALF OF WA AND NORTHEAST OR AT THIS TIME, ASSOCIATED WITH A WARM  
FRONT LIFTING ACROSS WASHINGTON STATE. A STRONG WESTERLY FLOW  
ALOFT IS PROVIDING RAIN SHADOWING OFF THE CASCADES, LEAVING A  
LARGE GAP IN PRECIPITATION ACROSS THE LOWER COLUMBIA BASIN. AS THE  
WARM FRONT LIFTS INTO NORTHERN WA, PRECIPITATION WILL BE MAINLY  
CONFINED TO THE WA CASCADES AND FAR NORTHERN BLUE MOUNTAINS BY  
EARLY THURSDAY MORNING. WINDS HAVE DECREASED ACROSS THE AREA AND  
SHOULD REMAIN LIGHT FOR MOST OF THE NIGHT BEFORE INCREASING BEHIND  
THE FRONT THURSDAY MORNING. FORECAST ON TRACK AND ONLY MINOR  
UPDATES WERE MADE. WISTER  
 

 
   
AVIATION...06Z TAFS
 
A WARM FRONT MOVING ONSHORE WILL LOWER  
CIGS OVER THE NEXT SEVERAL HOURS BUT STILL REMAIN VFR AT THE  
TERMINAL AIRPORTS. ANY RAINFALL THIS EVENING WILL BE VERY LIGHT WITH  
AROUND A TRACE. WINDS HAVE DECREASED THIS EVENING AND MOSTLY 15 KTS  
OR LESS BUT WILL INCREASE AFTER THE WARM FRONTAL PASSAGE WITH WSW 10-  
15 KTS GUSTING TO 25 KTS THURSDAY MORNING. THURSDAY WILL BE MET WITH  
VARIABLE MID AND HIGH LEVEL CLOUDS WITH BASES AROUND 7K-15K FEET,  
AND WSW WINDS GUSTING TO 20-25 KTS. WISTER  
 

 
 
   
PREV DISCUSSION
 
/ISSUED 500 PM PDT WED OCT 27 2021/  
 
SHORT TERM...HEADING INTO THURSDAY, BREEZY TO LOCALLY WINDY S-SW  
WINDS WILL DEVELOP, AND AFTERNOON HIGHS WILL BE AROUND 10-15  
DEGREES WARMER THAN TODAY. STRONGEST WINDS WILL BE ALONG EXPOSED  
RIDGES IN THE SIMCOE HIGHLANDS AND EASTERN SLOPES OF THE CASCADES,  
THOUGH AREAS OF NORTH-CENTRAL OR AND THE COLUMBIA BASIN OF WA  
COULD SEE GUSTS OF 30-35 MPH. NO WIND HIGHLIGHTS ARE EXPECTED AT  
THIS TIME. PRECIPITATION ON THURSDAY WILL LARGELY BE CONFINED TO  
THE MOUNTAINS, PRIMARILY THE WA CASCADES, AS THE WARM FRONT PUSHES  
NORTH AND A PLUME OF MOISTURE IS DIRECTED INTO THE WA CASCADES.  
 
THE WARMER TEMPERATURES WILL BE SHORT LIVED AS A COLD FRONT WILL  
SWEEP ACROSS THE REGION FROM NW TO SE FRIDAY MORNING, BRINGING  
HIGHS SIMILAR TO THIS AFTERNOON AND A RENEWED CHANCE OF  
PRECIPITATION FOR OUR ENTIRE CWA. THE BEST CHANCES FOR  
PRECIPITATION WILL BE FAVORED UPSLOPE AREAS SUCH AS THE BLUES,  
THOUGH LOWER ELEVATIONS COULD ALSO PICK UP A FEW HUNDREDTHS OF AN  
INCH OF RAIN. PRECIPITATION WILL LINGER ACROSS THE SOUTHERN AND  
EASTERN PORTIONS OF OUR CWA FRIDAY AFTERNOON AND EVENING WITH  
DRIER CONDITIONS RETURNING OVERNIGHT. PLUNKETT/86  
 
LONG TERM...SATURDAY THROUGH WEDNESDAY...A LOT OF MODEL UNCERTAINTY  
THROUGH THE EXTENDED PERIOD. MODEL ISSUES BEGIN SATURDAY WITH THE  
WAY MODELS HANDLE THE CLOSED LOW OFF THE SW COAST OF OREGON. GFS IS  
MOST AGGRESSIVE IN OPENING THE CLOSED LOW INTO A TROUGH AND MOVE IT  
INTO THE GREAT BASIN BY LATE SATURDAY. OTHER MODELS HOLD THE CLOSED  
LOW AROUND SW OREGON INCLUDING THE ECMWF AS A RIDGE PATTERN BUILDS  
ALONG THE COAST. THE ECMWF ATTEMPTS TO BRING THE DECAYING LOW INTO  
THE PACIFIC NORTHWEST LATE SATURDAY AND SUNDAY UNDER THE RIDGE AXIS  
WHICH IS ALSO MOVING ONSHORE. NBM BLENDS THE DIFFERENCE TO INDICATE  
A SLIGHT CHANCE OF PRECIPITATION IN CENTRAL OREGON SATURDAY BUT WITH  
LOW CONFIDENCE.  
 
THE RIDGE AXIS BEGINS TO SHIFT EASTWARD LATE SUNDAY INTO MONDAY AS  
THE NEXT SYSTEM APPROACHES FROM THE WEST. ONCE AGAIN MODELS DIFFER  
ON THE INTENSITY AND PLACEMENT OF THE FEATURES BY MONDAY WITH THE  
ECMWF BEING THE MORE AGGRESSIVE WHILE GFS MAINTAINS MORE OF A FLAT  
RIDGE OVER THE REGION. STAYED WITH THE NBM WHICH MITIGATES A  
WEAKENING SYSTEM PASSING OVER THE FORECAST AREA ON MONDAY.  
 
MODELS SOMEHOW MANAGE TO AGREE ON A TRANSITORY RIDGE OF HIGH  
PRESSURE OVER THE FORECAST AREA ON TUESDAY. HOWEVER, THE GFS RIDGE  
AXIS IS OVER THE FORECAST AREA BY TUESDAY AFTERNOON WHILE THE ECMWF  
KEEPS IT ALONG THE COAST. THE RESULT IS THE GFS BEING FASTER AT  
MOVING THE NEXT WEATHER SYSTEM INTO THE FORECAST AREA ON WEDNESDAY  
WHILE THE ECMWF STILL HAS THE RIDGE AXIS PASSING OVER THE FORECAST  
AREA. AGAIN THE NBM SPLITS THE DIFFERENCE INDICATING AT LEAST A  
SLIGHT CHANCE OF PRECIPITATION. ALL THIS UNCERTAINLY LEAD TO A VERY  
LOW CONFIDENCE IN THE EXTENDED FORECAST AT THIS POINT.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 44 73 48 59 / 30 10 10 60  
ALW 47 74 51 61 / 40 10 10 70  
PSC 49 73 55 63 / 40 10 10 50  
YKM 39 66 45 59 / 40 20 10 20  
HRI 46 74 52 62 / 30 10 10 60  
ELN 39 62 44 55 / 70 50 50 20  
RDM 43 69 44 56 / 10 0 10 50  
LGD 42 63 47 57 / 40 10 10 50  
GCD 43 70 45 61 / 20 0 0 30  
DLS 48 69 53 61 / 60 20 20 50  
 

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

 
 

 
 
SHORT TERM...85  
LONG TERM....91  
AVIATION...85  
 
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