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.
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page