324  
FXUS66 KPQR 071636 AAA  
AFDPQR  
 
AREA FORECAST DISCUSSION...UPDATED  
NATIONAL WEATHER SERVICE PORTLAND OR  
932 AM PDT TUE JUL 7 2020  
 
UPDATED AVIATION/MARINE SECTIONS  
 
.SYNOPSIS..COOL TEMPERATURES AND A FEW LIGHT SHOWERS TODAY.  
TEMPERATURES WILL GRADUALLY WARM THROUGH THE REMAINDER OF THE WEEK.  
ANOTHER SYSTEM WILL MOVE INTO THE AREA ON THURSDAY, AND WILL LIKELY  
REINFORCE MORNING CLOUDS AND BRING COOLER TEMPERATURES FOR THE  
WEEKEND, BUT CONFIDENCE IN WHETHER OR NOT IT WILL PRODUCE RAIN ACROSS  
THE AREA REMAINS LOW.  
 

 
   
SHORT TERM...TODAY THROUGH THURSDAY
 
SATELLITE IMAGERY CONTINUES  
TO SHOW A TROUGH ANCHORED OVER THE PACIFIC NW THAT IS SLOWLY MOVING  
EASTWARD TODAY. WITHIN THE OVERALL FLOW PATTERN A FEW SHORTWAVES CAN  
BE VIEWED, WHICH WILL HELP TO MAINTAIN THIS PATTERN OF COOL  
TEMPERATURES, EXTENSIVE CLOUD COVER AND LIGHT PRECIPITATION THAT  
HAS HAPPENED OVER THE PAST FEW DAYS. THERE IS THE CHANCE THAT TOWARDS  
THE AFTERNOON SOME SUNBREAKS COULD BE EXPERIENCED BUT WILL LIKELY NOT  
IMPACT THE OVERALL PATTERN. SHOWERS CHANCES WILL DIMINISH THROUGH THE  
EVENING HOURS AS A RIDGE SLOWLY STARTS TO BUILD IN ACROSS THE AREA.  
 
WEDNESDAY, THE RIDGE WILL BE WELL ESTABLISHED AND PROVIDE SLIGHTLY  
DRIER AND WARMER CONDITIONS ACROSS THE CWA. A WEAK FRONTAL SYSTEM  
WILL LIKELY STALL ACROSS THE EASTERN PACIFIC OCEAN. THERE ARE A FEW  
WEAK PERTURBATIONS IN THE GENERAL FLOW PATTERN, WHICH ORIGINATE FROM  
THE GULF OF ALASKA, THAT WILL LIKELY PUSH THIS STALLED FRONT ACROSS  
THE AREA.  
 
THIS SCENARIO WILL LIKELY RESULT IN A SLIGHT INCREASE TO  
PRECIPITATION CHANCES FOR AREAS ALONG THE FAR NORTH OREGON  
COAST/SOUTH WASHINGTON COAST, WITHIN THE NORTH AND CENTRAL WILLAMETTE  
VALLEY AND ALONG THE CASCADES FOR THURSDAY. HOWEVER, CONFIDENCE IS  
CURRENTLY LOW. /42  
 
   
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
 
MODELS AND THEIR  
ENSEMBLES ARE IN DECENT AGREEMENT A LONGWAVE TROUGH WILL PERSIST  
ACROSS THE NORTHEAST PACIFIC AND PACIFIC NORTHWEST DURING THE SECOND  
HALF OF NEXT WEEK AND INTO NEXT WEEKEND. IT APPEARS THE REGION WILL  
BE UNDER UPPER LEVEL SOUTHWESTERLY FLOW FRIDAY INTO SATURDAY WITH THE  
MAIN UPPER LEVEL TROUGH GENERALLY REMAINING OVER SOUTHERN BC AND JUST  
OFFSHORE WITH LOW AMPLITUDE UPPER LEVEL RIDGING BUILDING OVER THE  
ROCKY MOUNTAIN STATES. THIS SHOULD KEEP THE AREA MAINLY DRY, BUT  
CANNOT COMPLETELY RULE OUT AREAS OF MORNING DRIZZLE AND/OR A WEAK  
AFTERNOON SHOWER ACROSS MAINLY SOUTHWEST WASHINGTON. NONETHELESS, IT  
APPEARS INCREASINGLY LIKELY HIGH TEMPERATURES WILL TOP OUT NEAR  
AVERAGE TO POSSIBLY EVEN A COUPLE DEGREES ABOVE AVERAGE BY SATURDAY.  
 
MOVING INTO SUNDAY, UNCERTAINTY IN THE FORECAST GROWS DUE TO THE  
AMPLITUDE AND TIMING OF ANOTHER TROUGH MOVING ACROSS THE PACIFIC  
NORTHWEST. THE WPC CLUSTER ANALYSIS CONTAINING CMCE, EPS AND GEFS  
ENSEMBLE DATA SUGGESTS ~45% OF THE MEMBERS SUPPORT A SOLUTION THAT  
WOULD DROP A FRONT INTO THE REGION ON SUNDAY THAT WOULD BRING AT  
LEAST SOME RAIN, POSSIBLY WETTING RAINS IN FAVORED TERRAIN, TO THE  
NORTHERN HALF OF THE CWA. ANOTHER 20% OF THE MEMBERS SUGGEST A SLOWER  
SOLUTION THAT WOULD LIKELY HOLD THIS OFF UNTIL SUNDAY NIGHT OR  
MONDAY. MEANWHILE, ANOTHER 40% SUGGEST A MUCH LOWER AMPLITUDE  
SHORTWAVE TROUGH THAT BRUSHES THE REGION AS IT MOVES EASTWARD ACROSS  
SOUTHERN CANADA. THIS LATTER SCENARIO WOULD LIKELY RESULT IN SOME  
COOLING AND AN INCREASE IN MORNING CLOUD COVER, BUT THE AREA WOULD  
LIKELY REMAIN DRY. NBM POPS AND TEMPERATURES SEEM TO CAPTURE THE  
UNCERTAINTY WITH THIS FEATURE WELL SO FEW DEVIATIONS WERE MADE FROM  
THIS FORECAST GUIDANCE. /NEUMAN  
 

 
   
AVIATION
 
EXTENSIVE MARINE LAYER COVERS THE FORECAST AREA THIS  
MORNING. 12Z KSLE SOUNDING SHOWED TOPS 060-070. MIX OF FLIGHT  
CONDITIONS AS OF 1630Z, WITH MVFR BECOMING THE MORE PREDOMINANT  
CATEGORY. PERIODIC -DZ AND/OR -RA RESULTING IN SPOTTY IFR  
CONDITIONS, ESPECIALLY ALONG THE COAST. DO NOT SEE MUCH CHANGE IN  
OVERALL CONDITIONS THROUGH AT LEAST EARLY AFTERNOON. WILL  
LIKELY SEE GRADUALLY INCREASING LOW-END VFR COVERAGE OVER THE  
INLAND AREAS MID-AFTERNOON THROUGH THE EVENING. COASTAL AREAS  
EXPECTED TO BE PRIMARILY MVFR THROUGH WED MORNING, WITH AREAS OF  
IFR, ESPECIALLY OVERNIGHT THROUGH WED MORNING. ALSO CANNOT RULE  
OUT LOCAL IFR AGAINST THE LOWER SLOPES OF THE CASCADES. FEW  
SHOWERS LIKELY THROUGH THE AFTERNOON AND EVENING.  
 
KPDX AND APPROACHES...LITTLE CHANGE TODAY, WITH PERSISTENT LOW  
VFR CIGS THROUGH THIS EVENING. MVFR POSSIBLE THROUGH EARLY  
AFTERNOON AND AGAIN LATE TONIGHT THROUGH WED MORNING. WEISHAAR  
 

 
   
MARINE
 
NO CHANGES TO CURRENT MARINE FORECAST. BENIGN  
CONDITIONS WILL PERSIST OVER THE WATERS FOR THE NEXT FEW DAYS.  
WIND SPEEDS GENERALLY 15 KT OR LESS. SEAS WILL HOVER IN THE 3 TO  
5 FT RANGE INTO THE WEEKEND. A DOMINANT LOW-AMPLITUDE SOUTH  
SWELL EVENTUALLY TRANSITIONS TO A SHORTER-PERIOD WEST TO  
NORTHWEST SWELL BY WED. WEISHAAR  
 

 
   
PQR WATCHES/WARNINGS/ADVISORIES
 
 
OR...NONE.  
WA...NONE.  
PZ...NONE.  

 
 

 
 
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