070  
FXUS66 KPDT 131110 AAA  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
410 AM PDT THU JUN 13 2024  
 
UPDATED AVIATION DISCUSSION  
   
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
 
MOSTLY CLEAR SKIES  
AND A DRY AIR MASS HAVE LED TO EFFICIENT RADIATIONAL COOLING FOR  
MOST AREAS, RESULTING IN COOL TEMPERATURES NEARLY AREA-WIDE.  
AFTER THE CHILLY START TO THE MORNING, TEMPERATURES WILL INCREASE  
THIS AFTERNOON WITH ANOTHER WARM, DRY DAY ANTICIPATED ACROSS THE  
FORECAST AREA. WINDS WILL BE LIGHT THROUGH AFTERNOON, BUT A SHARP  
UP-RAMP IN WINDS IS ANTICIPATED THIS EVENING THROUGH THE CASCADE  
GAPS AND INTO THE COLUMBIA BASIN AS ONSHORE-DIRECTED PRESSURE  
GRADIENTS STRENGTHEN IN RESPONSE TO AN APPROACHING TROUGH.  
FORECAST SOUNDINGS INDICATE A 30-40KT LLJ OVER THE COLUMBIA RIVER  
GORGE (CRG) AND KITTITAS VALLEY (KV) THIS EVENING THROUGH FRIDAY  
MORNING. CONFIDENCE IS HIGH (80% CHANCE) THAT WIND-PRONE  
LOCATIONS IN THE KV WILL APPROACH OR EXCEED 45 MPH WIND GUSTS SO  
HAVE OPTED TO ISSUE A WIND ADVISORY, VALID 8PM THIS EVENING UNTIL  
11AM FRIDAY MORNING. IN THE CRG AND ACROSS THE ADJOINING PORTIONS  
OF THE COLUMBIA BASIN (CB), NORTH-CENTRAL OR (N-C OR), AND THE  
FOOTHILLS OF THE BLUE MOUNTAINS (BMF), CONFIDENCE IS MODERATE  
(40-60% CHANCE) IN WINDS REACHING ADVISORY CRITERIA SO HAVE OPTED  
TO FORGO ANY HIGHLIGHTS. OF NOTE, THE NOCTURNAL NATURE OF THE  
EVENT DECREASES CONFIDENCE RELATIVE TO A DAYTIME EVENT.  
 
FRIDAY, WINDS WILL REMAIN BREEZY TO WINDY AS THE FIRST IN A SERIES  
OF SHORTWAVES WRAPS AROUND A DEEP, UPPER-LEVEL CLOSED LOW AND  
EJECTS NORTHEASTWARD INTO NORTHERN WA AND SOUTHERN BC. DUE TO THE  
TRAJECTORY OF THE IMPULSE, PRECIPITATION CHANCES (15-60%) WILL BE  
CONFINED TO THE CASCADE CREST OF WA ON FRIDAY.  
 
SATURDAY, THE SECOND SHORTWAVE IS ADVERTISED TO PUNCH ACROSS THE  
FORECAST AREA, RESULTING IN ANOTHER ROUND OF BREEZY TO WINDY  
ONSHORE WINDS. WINDS MAY APPROACH ADVISORY CRITERIA FOR WIND-  
PRONE LOCATIONS SUCH AS THE KV, CRG, AND PORTIONS OF THE CB AND  
BMF (50-80% CHANCE), BUT HAVE OPTED TO HOLD OFF ON ANY HIGHLIGHTS  
FOR NOW.  
 
PRECIPITATION CHANCES WILL INCREASE SATURDAY, BUT THE BEST CHANCES  
(60-90%) WILL STILL BE PINNED TO THE CASCADE CREST. ELSEWHERE,  
CHANCES ARE <15% FOR MOST OF THE CB AND CENTRAL OR (C OR), WHILE  
CHANCES ARE HIGHER (15-40%) FOR THE BMF AND BLUE MOUNTAINS (BM).  
CONFIDENCE IS LOW (<20% CHANCE) IN THUNDERSTORMS SATURDAY  
AFTERNOON, BUT STEEP LOW- AND MID-LEVEL LAPSE RATES WILL LEAD TO  
MODEST INSTABILITY. PLUNKETT/86  
 

 
   
LONG TERM...SUNDAY THROUGH THURSDAY
 
THE FORECAST STARTS OUT  
ON SUNDAY WITH SOME DISCREPANCIES ON THE TIMING AND LOCATION OF AN  
UPPER LOW THAT WILL IMPACT THE REGION EARLY NEXT WEEK. THE  
MAJORITY OF THE CLUSTERS FAVOR A MORE OFFSHORE SOLUTION ON SUNDAY  
SIMILAR TO THE DETERMINISTIC GFS COMPARED TO THE MORE PROGRESSIVE  
ECMWF. THIS WILL KEEP SHOWER ACTIVITY (30-40% CHANCE) CONFINED TO  
THE CASCADE CREST DURING THE DAY ON SUNDAY.  
 
ON MONDAY AND MONDAY NIGHT RAIN SHOWERS WILL SPREAD ACROSS THE  
REGION AS THE UPPER LOW MOVES ACROSS THE REGION...WITH THE  
POTENTIAL FOR WRAP AROUND PRECIPITATION OVER THE FOOTHILLS AND  
BLUE AND WALLOWA MOUNTAINS ON TUESDAY. THERE IS A LOW CHANCE  
(10-20%)OF TSTMS MONDAY AFTERNOON AND EVENING MAINLY IN GRANT  
COUNTY BUT ANY STORMS WILL REMAIN RATHER ISOLATED AND BRIEF GIVEN  
MARGINAL INSTABILITY.  
 
QPF AMOUNTS MONDAY THROUGH TUESDAY ARE FORECAST TO BE AROUND  
.50 INCHES IN THE FOOTHILLS OF THE BLUES AND AROUND 1.00 INCH IN  
THE EASTERN MOUNTAINS WITH LIGHTER AMOUNTS ELSEWHERE. RIGHT NOW  
THERE IS A DISCONNECT BETWEEN THE NBM QPF AND POPS. DESPITE THE  
HIGHER QPF AMOUNTS THE POPS ARE MODEST AT ONLY 30-50%. CONSIDERED  
BUMPING POPS UP BUT THE ECMWF AND GFS ENSEMBLE MEMBERS SHOW  
CONSIDERABLE SPREAD IN QPF AMOUNTS WITH SOME MEMBERS SHOWING HEAVY  
QPF AND OTHERS NONE AT ALL (AT KPDT AND KMEH FOR REFERENCE).  
ROUGHLY 10% OF THE ENSEMBLE MEMBERS ARE INDICATING THE POTENTIAL  
FOR RAINFALL EXCEEDING 1.00 INCH AT KPDT AND 2.00 INCHES AT KMEH.  
THINK THE QPF AND POP INCONSISTENCY WILL DECREASE WITH TIME AS THE  
EVENT GETS CLOSER.  
 
THE CLUSTERS SHOW CONSIDERABLE SPREAD ON HOW QUICKLY THE UPPER LOW  
MOVES EAST OF THE REGION ON WEDNESDAY. WENT WITH THE NBM WHICH  
DRIES THINGS OUT ON WEDNESDAY BUT IF THE LOW EXITS THE REGION  
MORE SLOWLY, THERE COULD BE LINGERING SHOWERS OVER THE NORTHEAST  
MOUNTAINS.  
 
THERE IS LOW-MODERATE CONFIDENCE (40-50%) IN THE FORECAST FOR  
THURSDAY GIVEN THE DIFFERING CLUSTER SOLUTIONS. IT DOES APPEAR  
THAT THE FLOW WILL BE SLIGHTLY LESS AMPLIFIED WHICH WILL ALLOW  
TEMPERATURES TO WARM UP. IN FACT AFTER HIGH TEMPERATURES BOTTOM  
OUT AT 10-15 DEGREES BELOW NORMAL SUNDAY AND MONDAY A WARMING  
TREND WILL OCCUR THROUGH THURSDAY SUCH THAT HIGH TEMPERATURES WILL  
BE RIGHT ABOUT NORMAL THURSDAY AFTERNOON. 78  
 

 
   
AVIATION...12Z TAFS
 
VFR CONDITIONS ARE EXPECTED THROUGH THE  
PERIOD WITH INCREASING CLOUDS AT 15-25 KFT AGL. WINDS WILL BE 5-12  
KT EXCEPT 15G25KT LATE THIS AFTERNOON AND TONIGHT AT KDLS...KRDM AND  
KBDN. 78  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 83 51 73 48 / 0 0 0 0  
ALW 86 55 77 51 / 0 0 0 0  
PSC 88 56 80 54 / 0 0 0 0  
YKM 85 48 76 46 / 0 0 0 0  
HRI 88 55 79 52 / 0 0 0 0  
ELN 82 49 71 45 / 0 0 0 0  
RDM 82 42 72 41 / 0 0 0 0  
LGD 84 49 72 45 / 0 0 0 0  
GCD 88 48 75 43 / 0 0 0 0  
DLS 84 51 73 51 / 0 0 0 0  
 

 
   
PDT WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...WIND ADVISORY FROM 8 PM THIS EVENING TO 11 AM PDT FRIDAY FOR  
WAZ026.  
 

 
 

 
 
SHORT TERM...86  
LONG TERM....78  
AVIATION...78  
 
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