215
FXUS66 KPQR 141213 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
512 AM PDT FRI AUG 14 2026
..UPDATED PUBLIC AND AVIATION DISCUSSIONS
SYNOPSIS
WARM AND DRY CONDITIONS EXPECTED THROUGH NEXT WEEK
WITH PERSISTENT ONSHORE FLOW. SLIGHT CHANCES (10-20%) FOR
THUNDERSTORMS OR SHOWERS OVER THE CASCADES THIS AFTERNOON AND
SATURDAY AFTERNOON, WITH THE HIGHEST CHANCES ALONG THE CREST OF
THE CASCADES.
UPDATE
RADAR AND SATELLITE IMAGERY AROUND 2:30-3 AM EARLY THIS
MORNING SHOWED THUNDERSTORMS POPPING UP IN THE WESTERN PORTLAND
METRO AREA. MESOANALYSIS AT THE TIME INDICATED MUCAPE VALUES AROUND
100-500 J/KG. GIVEN THAT WE HAD A LOW-LEVEL INVERSION AROUND 2000-
4000 FEET THIS MORNING WHICH IS MAINTAINING LOW STRATUS CLOUDS, A
LOT OF THE INSTABILITY AND THUNDERSTORMS ORIGINATED IN THE MID TO
UPPER LEVELS OF THE ATMOSPHERE. THIS WAS EVIDENT BY THE METARS SHOWN
FROM KHIO AND KSPB WHICH REPORTED THUNDERSTORMS WITH CLOUD BASES
AROUND 9000-10000 FT. AS OF 5 AM FRIDAY, THESE THUNDERSTORMS HAVE
MOVED INTO THE NORTHERN CLARK COUNTY AND COWLITZ VALLEY AREAS. THESE
SEEM TO BE VERY ISOLATED THUNDERSTORMS, SO A SLIGHT CHANCE (15%) FOR
THUNDERSTORMS WERE ADDED TO THE FORECAST ACROSS PARTS OF THE
PORTLAND/VANCOUVER METRO, COWLITZ COUNTY, AND SKAMANIA COUNTY
THROUGH AT LEAST 6 AM THIS MORNING. -10
DISCUSSION...TODAY THROUGH THURSDAY
SATELLITE IMAGERY AND
SURFACE OBSERVATIONS AS OF EARLY FRIDAY MORNING DEPICTS ONSHORE
FLOW SUPPORTING A SOLID MARINE LAYER ALONG THE COAST WITH
STRATUS CLOUDS PUSHING THROUGH THE GAPS OF THE COAST RANGE AND
THROUGH THE LOWER COLUMBIA RIVER INTO THE COWLITZ VALLEY. BY 5-7
AM FRIDAY, EXPECT STRATUS CLOUDS TO MAKE IT'S WAY INTO THE REST
OF THE I-5 CORRIDOR INCLUDING THE WILLAMETTE VALLEY. AFTER 9-11
AM FRIDAY, CLOUDS ACROSS INTERIOR VALLEYS SHOULD BEGIN CLEARING
OUT AS DAYTIME HEATING PROGRESSES AND INCREASES MIXING.
MEANWHILE, THERE REMAINS UNCERTAINTY WITH HOW MUCH CLEARING WILL
OCCUR AT THE COAST. THERE IS ABOUT A 50-60% CHANCE AT ANY GIVEN
HOUR BETWEEN 2-7 PM FOR MARINE STRATUS BREAKING OUT ALONG THE
NORTH OREGON COAST, BUT LOWER CONFIDENCE FOR CLEARING ALONG THE
CENTRAL OREGON COAST.
EXPECT DRY AND WARM CONDITIONS TODAY AND THROUGH THE WEEKEND FOR
THE MAJORITY OF LOCATIONS AS WEAK RIDGING BUILDS OVER THE
PACIFIC NORTHWEST AND AN UPPER LEVEL TROUGH ELONGATES WELL-
OFFSHORE OVER THE NORTHEAST PACIFIC OCEAN. AN EXCEPTION WOULD BE
THE CASCADES, WHERE THERE IS A 10-25% CHANCE FOR ISOLATED
THUNDERSTORMS THIS AFTERNOON AND SATURDAY AFTERNOON. AS
SHORTWAVES FROM THE BROAD PARENT TROUGH OFFSHORE BRINGS MORE
SOUTHERLY FLOW ALOFT OVER THE AREA, WILL SEE INCREASING
INSTABILITY AND MONSOONAL MOISTURE SUPPORTING THESE THUNDERSTORM
CHANCES. ANY THUNDERSTORMS THAT DEVELOP MAY BRING LIGHTNING,
BRIEF HEAVY RAIN, AND ERRATIC WINDS. OTHERWISE, THE GENERAL
AIRMASS REMAINS TOO DRY TO SUPPORT ANY WIDESPREAD PRECIPITATION
WEST OF THE CASCADES. GUIDANCE SUGGESTS HIGH CONFIDENCE FOR NEAR
TO SLIGHTLY ABOVE AVERAGE TEMPERATURES FOR MID-AUGUST THROUGH
THE WEEKEND, WITH AFTERNOON HIGHS WARMING INTO THE MID TO UPPER
80S ACROSS INTERIOR VALLEYS.
EARLY NEXT WEEK, CLUSTER ANALYSIS OF 500 MB HEIGHTS CONTINUE TO
SUGGEST DRY AND SEASONABLY WARM CONDITIONS AS BROAD UPPER LEVEL
TROUGHING REMAINS WELL-OFFSHORE AND AN UPPER LEVEL RIDGE AXIS
OVER THE ROCKIES TILTS INTO THE PACIFIC NORTHWEST. BY MID-WEEK,
ENSEMBLES DIVERGE INTO VARIOUS UPPER LEVEL PATTERNS. A LITTLE
OVER HALF OF ENSEMBLE MEMBERS ARE FAVORING A TROUGH ENTERING THE
PACIFIC NORTHWEST AND RETURNING COOLER TEMPERATURES, WHILE THE
OTHER HALF FAVORS WARMER CONDITIONS DUE TO ZONAL FLOW OR
AMPLIFIED RIDGING. EITHER WAY, NO PRECIPITATION IS FORECAST AS
WE MAINTAIN A DRY SUMMERTIME AIRMASS. -10
AVIATION...THROUGH 12Z SAT
SATELLITE IMAGERY AND TERMINAL
OBSERVATIONS AS OF EARLY FRIDAY MORNING DEPICTS WIDESPREAD MARINE
STRATUS ALONG THE COAST, WITH LOW-END MVFR CIGS (1-2 KFT) ALONG THE
NORTH OREGON COAST AND LIFR CIGS ALONG THE CENTRAL OREGON COAST.
SOME OF THE STRATUS AS MADE ITS WAY INTO THE I-5 CORRIDOR ALSO WITH
LOW-END MVFR CIGS ACROSS THE EASTERN PORTLAND/VANCOUVER METRO AREA
AND THE SOUTHERN WILLAMETTE VALLEY. STILL SOME UNCERTAINTY IF THESE
MVFR CIGS WILL MAKE IT INTO THE CENTRAL WILLAMETTE VALLEY. FOR THE
INTERIOR VALLEYS WITH MVFR STRATUS ALREADY, THERE IS HIGH CONFIDENCE
THESE TRENDS CONTINUE THROUGH THE MORNING. AFTER 17-19Z FRI, DAYTIME
HEATING WILL INCREASE MIXING AND HELP CLEAR OUT STRATUS ACROSS
INTERIOR VALLEYS, RETURNING VFR CONDITIONS THROUGH THE REST OF THE
TAF PERIOD. ALONG THE COAST, THERE IS A 50-60% CHANCE AT ANY GIVEN
HOUR BETWEEN 21Z FRI-01Z SAT FOR BRIEF IMPROVEMENT TO VFR AT KAST,
BUT LOWER CHANCES (20-30%) FOR KONP. WESTERLY TO NORTHWESTERLY WINDS
GENERALLY AROUND 5-10 KT TODAY, STRONGEST IN THE AFTERNOON.
WILL NOTE THERE WERE SOME THUNDERSTORMS OBSERVED THIS MORNING AROUND
THE PORTLAND METRO AREA. THESE THUNDERSTORMS HAVE MOVED NORTHWARD
INTO THE COWLITZ VALLEY AND ARE NOT EXPECTED THE REST OF THE DAY
(<10% CHANCE FOR THUNDERSTORMS).
KPDX AND APPROACHES...MVFR CIGS THROUGH 18Z FRI, SCATTERING OUT AND
IMPROVING TO VFR AFTER 18Z FRI. EXPECT VFR CONDITIONS THE REST OF
THE TAF PERIOD WITH FEW HIGH CLOUDS. NORTHWESTERLY WINDS AROUND 3-7
KT, STRONGEST IN THE AFTERNOON. -10
MARINE
NO SIGNIFICANT CHANGES IN THE OVERALL PATTERN AS HIGH
PRESSURE OFFSHORE WILL CONTINUE TO SUPPORT NORTHERLY WINDS ALONG
WITH BENIGN CONDITIONS ACROSS ALL WATERS THROUGH NEXT WEEK. WINDS
FROM THE NORTH TO NORTHWEST WITH GUSTS LESS THAN 21 KTS WILL
CONTINUE THROUGH AT LEAST THE WEEKEND, WITH WIND DRIVEN SEAS
EXPECTED TO REMAIN AROUND 3-5 FT. -10/42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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