406  
FXUS66 KPDT 282326  
AFDPDT  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PENDLETON OR  
426 PM PDT THU MAR 28 2024  
 
UPDATED AVIATION DISCUSSION  
   
SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT
 
SCATTERED SHOWERS  
HAVE DEVELOPED OVER THE FORECAST AREA, AND A COUPLE OF THUNDERSTORMS  
HAVE ALSO BEEN OBSERVED. HEAVY RAIN, SMALL HAIL AND OUTFLOW WINDS  
AS STRONG AS 35 MPH WERE REPORTED WITH SOME OF THE SHOWERS. THERE  
ARE STEEP MID-LEVEL LAPSE RATES OF 7.5 C/KM ALONG WITH SBCAPES OF  
250-500 J/KG AND 30-35KTS OF BULK SHEAR ON SPC'S MESOSCALE  
ANALYSIS. ALTHOUGH NOT EASILY DETECTED ON WATER VAPOR LOOPS, THERE  
ARE SEVERAL EMBEDDED WAVES ROTATING AROUND A DEEP UPPER LOW  
OFFSHORE. THESE DISTURBANCES COMBINED WITH DIURNAL HEATING HAVE  
CONTRIBUTED TO THE SHOWERS AND THUNDERSTORMS. SURPRISINGLY, PWATS  
ARE ONLY AROUND 0.35-0.5". THEREFORE, CONFIDENCE IS HIGH (70%)  
THAT SOME SHOWERS WILL BRING BRIEF HEAVY DOWNPOURS DUE TO THE  
INSTABILITY AND SHEAR BUT LOW (20%) OF ANY FLOODING THIS EVENING.  
SIMILAR TO YESTERDAY, THE CONVECTION WILL DECREASE THIS EVENING  
AND--FOR THE MOST PART-- END OVERNIGHT. BY EARLY FRIDAY, THERE IS  
A CHANCE (30%) OF SHOWERS ALONG THE CASCADES AND THE WALLOWA MTNS.  
 
A COMPLEX PATTERN WILL SET UP OVERNIGHT AND FRIDAY. AN UPPER LOW  
ABOUT 130 MILES WEST OF THE WA COAST WILL PINWHEEL AROUND A  
DEVELOPING LOW ALONG THE BACKSIDE OF THE MAIN UPPER LEVEL TROUGH AND  
MERGE TOGETHER. BY FRIDAY AFTERNOON, THE MERGING LOWS WILL TRAVEL  
SOUTH AND SET UP OFF THE NORTHERN CA COAST. THIS LEAVES THE PACNW  
UNDER A SPLIT FLOW ALOFT. MEANWHILE, A WEAK SHORTWAVE TROUGH WILL  
TRAVEL ACROSS NORTHERN WA FRIDAY AFTERNOON. SCATTERED SHOWERS WILL  
ONCE AGAIN DEVELOP ON FRIDAY, AND MAINLY OVER THE MOUNTAINS WITH  
ABOUT A 40% COVERAGE OVER THE CWA. THE AIR MASS ON FRIDAY WILL  
NOT BE AS UNSTABLE AS TODAY, AND SPC SHOWS MOST OF THE GENERAL  
THUNDERSTORM OUTLOOK OVER NORTHERN WA AND THE ID PANHANDLE  
ASSOCIATED WITH THE NORTHERN SHORTWAVE. I CANNOT RULE OUT A STRAY  
THUNDERSTORM OR TWO SOMEWHERE IN OUR FORECAST AREA.  
 
LATE FRIDAY NIGHT AND SATURDAY WILL BE MOSTLY DRY WITH A FEW  
SPRINKLES OR FLURRIES OVER THE MOUNTAINS. THE CA LOW WILL  
CONTINUE ITS PATH SOUTHWARD, AND A DRY NNW FLOW ALOFT WILL DEVELOP  
OVER WA AND NORTHERN OR. AFTER A CHILLY START TO SATURDAY MORNING  
WITH EARLY MORNING LOWS IN THE 20S AND 30S AND MOSTLY CLEAR  
SKIES, SATURDAY AFTERNOON WILL BE SEASONAL AND MOSTLY SUNNY.  
WISTER/85  
 
   
LONG TERM...SUNDAY THROUGH THURSDAY
 
A FEW SHOWERS REMAIN POSSIBLE  
AT THE START OF THE FORECAST PERIOD AS THE PREVIOUS AREA OF LOW  
PRESSURE CONTINUES TO DIVE SOUTH. AS IT PROGRESSES SOUTHWARD, IT  
WILL TAKE THE REMAINING MOISTURE WITH IT, BUT COULD PRODUCE SOME  
GUSTY WIND ACROSS CENTRAL OREGON. DEVELOPING NORTHWEST FLOW WILL AID  
IN THE DEVELOPMENT OF GENERALLY DRY AND CALMER CONDITIONS BY SUNDAY  
EVENING. CLUSTER ANALYSIS SUPPORTS THIS DEVELOPMENT WITH A DECENT  
AGREEMENT SEEN BETWEEN THE CLUSTERS. DRY CONDITIONS WILL PERSIST  
THROUGH MONDAY NIGHT. WARMING TEMPERATURES ON MONDAY WILL PRODUCE  
VALUES AROUND 10 DEGREES ABOVE NORMAL ACROSS THE REGION, ESPECIALLY  
ACROSS THE COLUMBIA BASIN.  
 
THE NEXT APPROACHING TROUGH WILL SEND SOME MOISTURE OVER THE PACNW AS  
EARLY AS TUESDAY MORNING ALONG THE OREGON/WASHINGTON COAST, THOUGH  
ANY SHOWER ACTIVITY ACROSS THE FORECAST AREA REMAINS VERY LOW (0-  
10%) THROUGH TUESDAY AFTERNOON, WITH THE ONLY EXCEPTION BEING THE A  
FEW SHOWERS OVER THE PEAKS OF THE WASHINGTON CASCADES IN EXTREME  
WESTERN KITTITAS COUNTY. TEMPERATURES WILL HAVE ONE LAST DAY OF  
ANTICIPATED WARMING, WITH VALUES PEAKING AT 15 TO 20 DEGREES ABOVE  
NORMAL. THESE VALUES ARE BEING HIGHLIGHTED AS CLIMATOLOGICALLY  
ABNORMAL ON THE EXTREME FORECAST INDEX.  
 
SHOWERS WILL INCREASE THROUGH WEDNESDAY ACROSS THE FORECAST AREA.  
THE CASCADES REMAIN THE MOST FAVORABLE LOCATION FOR PRECIPITATION (30-  
60%), WITH THE BLUE MOUNTAINS ALSO SEEING A SLIGHT TO MODERATE  
CHANCE (25-45%). LOWLAND LOCATIONS GENERALLY ANTICIPATED TO SEE A  
CONTINUED LOW PROBABILITY OF LESS THAN 20%. GUSTY TO BREEZY  
AFTERNOON WIND CURRENTLY FAVORED ON WEDNESDAY WITH THE MORE DEFINED  
ARRIVAL OF THE TROUGH. THE TROUGH WILL CONTINUE TO IMPACT WEATHER  
CONDITIONS AS IT PROGRESSES SOUTHEAST ON THURSDAY. BETWEEN TUESDAY  
AND THURSDAY, TEMPERATURES WILL SEE A 15 TO 20 DEGREE DIP.  
BRANHAM/76  
 

 
   
AVIATION...00Z TAFS
 
OVERALL EXPECTING VFR CONDITIONS BUT WITH  
SOME ISOLATED MVFR POSSIBLE THROUGH 04Z DUE TO SHOWERS WHICH  
DECREASE AND END AFTER THIS TIME. PARTLY CLOUDY CONDITIONS FRIDAY  
WITH SOME ISOLATED SHOWERS MAINLY OVER AND NEAR THE MOUNTAINS. SOME  
GUSTY WINDS REMAIN POSSIBLE THROUGH THE EVENING ASSOCIATED WITH  
SHOWERS THEN BECOMING LESS THAN 10KTS OVERNIGHT THROUGH FRIDAY.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
PDT 33 54 31 56 / 20 10 0 0  
ALW 36 56 33 59 / 30 30 0 0  
PSC 38 61 35 64 / 10 0 0 0  
YKM 32 59 31 63 / 10 10 0 0  
HRI 35 60 33 63 / 20 10 0 0  
ELN 31 55 31 60 / 10 10 0 0  
RDM 30 52 28 54 / 10 20 10 0  
LGD 31 51 30 55 / 50 30 0 0  
GCD 28 51 30 56 / 30 30 10 0  
DLS 37 59 37 65 / 20 10 0 0  
 

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

 
 

 
 
SHORT TERM...85  
LONG TERM....76  
AVIATION...76  
 
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