487
FXUS66 KPQR 142134
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
234 PM PDT FRI AUG 14 2026
SYNOPSIS
WARM AND DRY CONDITIONS EXPECTED THROUGH NEXT WEEK
WITH PERSISTENT ONSHORE FLOW. SLIGHT CHANCES (15-30%) FOR
ISOLATED THUNDERSTORMS OR SHOWERS OVER THE CASCADES THIS
AFTERNOON AND SATURDAY AFTERNOON, WITH INCREASING CHANCES FOR
ISOLATED ELEVATED THUNDERSTORMS OVER THE WILLAMETTE VALLEY,
COAST RANGE, AND CASCADES AFTER 2 AM SATURDAY.
DISCUSSION...FRIDAY AFTERNOON THROUGH THURSDAY
UPPER LEVEL
PATTERN CONTINUES TO SHOW LONGWAVE TROUGHING OVER THE PACIFIC
OCEAN WITH RIDGING OVER THE CENTRAL US. SHORTWAVES ALONG THE
TROUGH ARE SLOWLY MOVING NORTH FROM N CA INTO OR TODAY AND
SATURDAY, BRINGING SOUTHERLY FLOW AND MONSOONAL MOISTURE TO THE
AREA. THIS PATTERN IS PRODUCING A 15-30% CHANCE OF AFTERNOON AND
EVENING THUNDERSTORMS TO THE CASCADE CREST TODAY AND SATURDAY.
STORMS THAT FORM WILL SLOWLY MOVE NORTHEAST OFF OF THE CREST.
THESE THUNDERSTORMS COULD PRODUCE HEAVY RAIN, GUSTY WINDS, SMALL
HAIL, AND FREQUENT LIGHTNING.
ADDITIONALLY, LATEST CAMS ARE INDICATING INCREASING POTENTIAL
(10-15% CHANCE) FOR ELEVATED CONVECTION IN THE EARLY MORNING
HOURS OF SATURDAY SPREADING ACROSS THE ENTIRETY OF NW OR AND SW
WA. A SUBTLE SHORTWAVE ALONG THE FLOW COULD PRODUCE ENOUGH
VORTICITY TO TAP INTO JUST ENOUGH EXISTING ELEVATED INSTABILITY
COMBINED WITH THE MONSOONAL MOISTURE FOR ISOLATED THUNDERSTORMS
TO FORM, MAINLY OVER THE WILLAMETTE VALLEY AND COST RANGE,
THOUGH CAN'T RULE ANY OUT OVER THE COAST OR CASCADES. IF ANY
STRONGER CELLS OR THUNDERSTORMS DO FORM, THEY WOULD MOVE
GENERALLY NORTH TO NORTHEAST AND COULD FORM ANYTIME AFTER 2 AM
WITH CHANCES LINGERING THROUGH THE MORNING HOURS. SINCE BASES
WILL BE HIGHER WITH THESE, THE MAIN IMPACTS WOULD BE FREQUENT
LIGHTNING WITH LOCALLY MODERATE TO HEAVY RAIN. GUSTY WINDS AND
SMALL HAIL ARE NOT AS LIKELY. A SIMILAR PATTERN OCCURRED EARLY
THIS MORNING, LEADING TO A FEW ISOLATED THUNDERSTORMS TO FORM
WEST OF PORTLAND AROUND 2-3 AM AND SLOWLY MOVE NORTHEAST INTO
SKAMANIA COUNTY, LINGERING THERE UNTIL LATE MORNING. THIS
PROVIDES HIGHER CONFIDENCE IN THE FORECAST SATURDAY MORNING,
THOUGH THE AREA THAT COULD RECEIVE THUNDERSTORMS IS WIDER THAN
THIS MORNING.
OTHERWISE, EXPECT MOSTLY DRY AND SEASONABLE TEMPERATURES TODAY
AND THROUGH THE WEEKEND FOR THE MAJORITY OF LOCATIONS. MARINE
STRATUS CONTINUES ALONG THE COAST THROUGH THE WEEKEND DUE TO THE
GENERAL ONSHORE FLOW WITH STRATUS PUSHING INLAND AT TIMES.
GUIDANCE SUGGESTS HIGH CONFIDENCE FOR NEAR NORMAL TEMPERATURES
FOR MID-AUGUST THROUGH THE WEEKEND, WITH AFTERNOON HIGHS WARMING
INTO THE LOW TO MID 80S ACROSS INTERIOR VALLEYS.
EARLY NEXT WEEK, CLUSTER ANALYSIS OF 500 MB HEIGHTS CONTINUE TO
SUGGEST DRY AND SEASONABLE 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. -03/10
AVIATION...THROUGH 00Z SUNDAY
SATELLITE AND TERMINAL
OBSERVATIONS SHOW VFR CONDITIONS WITH MOSTLY CLEAR SKIES INLAND
AND PERSISTENT MARINE STRATUS ALONG THE COAST. ALSO,
OBSERVATIONS ARE SHOWING SMOKE/HAZE ACROSS THE AIRSPACE, BUT
ABOVE THE SURFACE AND SLOWLY CLEARING. SMOKE/HAZE ACROSS THE
AIRSPACE COULD IMPACT SLANT RANGE AND VERTICAL VISIBILITIES
ANYTIME THROUGH 06Z SATURDAY FOR INLAND LOCATIONS.
COASTAL LOCATIONS ARE EXPECTED TO MAINTAIN MVFR CONDITIONS
THROUGH AT LEAST 06Z SATURDAY. AFTERWARDS, CONDITIONS ALONG THE
COAST ARE EXPECTED TO FALL BACK TOWARDS IFR/LIFR THROUGH AT LEAST
16Z SATURDAY, BECOMING MVFR ONCE AGAIN THROUGH THE MAJORITY OF THE
REST OF THE TAF PERIOD. AS FOR INLAND LOCATIONS, MVFR CONDITIONS
VIA MARINE STRATUS ARE EXPECTED TO RETURN AROUND 10Z-12Z SATURDAY,
IMPROVING TO VFR BY 18Z-21Z. WEST TO NORTHWEST WINDS GENERALLY
AROUND 5-10 KT WITH THE STRONGEST IN THE AFTERNOON. AROUND 03Z-05Z
SATURDAY, WINDS ARE EXPECTED TO BECOME LIGHT AND VARIABLE ACROSS
THE AIRSPACE.
STARTING AROUND 09Z SATURDAY AND THROUGH AT LEAST 15Z SATURDAY,
MODELS ARE SHOWING AROUND A 10-15% CHANCE FOR ELEVATED THUNDERSTORMS
DEVELOPING ANYWHERE WITHIN THE WILLAMETTE VALLEY AND COAST RANGE.
ANY THUNDERSTORMS THAT DEVELOP COULD RESULT IN FREQUENT LIGHTNING,
HEAVY RAIN, AND GUSTY AND ERRATIC WINDS.
KPDX AND APPROACHES...VFR CONDITIONS WITH MOSTLY CLEAR SKIES,
THOUGH ELEVATED SMOKE COULD MIX DOWN AT TIMES AND IMPACT SLANT
RANGE AND VERTICAL VISIBILITIES THROUGH 06Z SATURDAY. MVFR
CONDITIONS EXPECTED TO RETURN AROUND 12Z-15Z SATURDAY, IMPROVING
TO VFR BY 18Z-21Z. NORTHWESTERLY WINDS AROUND 3-7 KT, STRONGEST IN
THE LATE AFTERNOON AND EARLY EVENING. /42
MARINE
NO SIGNIFICANT CHANGES IN THE OVERALL PATTERN AS HIGH
PRESSURE OFFSHORE WILL CONTINUE TO SUPPORT NORTH/NORTHWESTERLY
WINDS WITH GUSTS LESS THAN 21 KTS. SEAS ALSO EXPECTED TO REMAIN
AROUND 3-5 FT. THESE BENIGN CONDITIONS ARE EXPECTED ACROSS ALL
WATERS THROUGH AT LEAST THE START OF NEXT NEXT WEEK. /42
FIRE WEATHER
THERE'S A 15-30% CHANCE OF ISOLATED
THUNDERSTORMS ALONG THE CASCADE CREST DURING THE AFTERNOON AND
EARLY EVENING HOURS TODAY AND SATURDAY. ADDITIONALLY, THERE'S A
10-15% CHANCE OF ISOLATED ELEVATED THUNDERSTORMS FORMING IN THE
WILLAMETTE VALLEY, COAST RANGE, AND CASCADES AFTER 2 AM
SATURDAY WITH CHANCES CONTINUING THROUGH THE MORNING HOURS. ANY
THUNDERSTORM THAT FORMS COULD HAVE FREQUENT LIGHTNING THAT COULD
STRIKE OUTSIDE OF AREAS RECEIVING RAIN. HOWEVER, DUE TO
PERSISTENT ONSHORE FLOW (WINDS GENERALLY FROM THE WEST TO
NORTHWEST), MINIMUM RELATIVE HUMIDITIES ARE WELL ABOVE CRITICAL
LEVELS (40S IN THE INTERIOR LOWLANDS, 30S TO 40S ALONG THE
CASCADE CREST), AND OVERNIGHT RECOVERIES WILL BE EXCEPTIONAL
(70S TO 90S). AVAILABLE WATER POTENTIAL IN THE ATMOSPHERE (PWAT)
VALUES ARE AROUND 0.75-0.8 INCHES OVER THE CASCADES AND
1.0-1.25 INCHES OVER THE INTERIOR LOWLANDS, WHICH MEANS ANY
THUNDERSTORM THAT FORMS WILL LIKELY PRODUCE MODERATE TO HEAVY
RAIN. ALTHOUGH STORMS OVER THE CASCADES COULD HAVE BRIEF PERIODS
OF GUSTY AND ERRATIC WINDS, IT WILL BE DIFFICULT FOR THESE WINDS
TO REACH WHERE LIGHTNING MIGHT STRIKE OUTSIDE OF RAIN CORES,
LIMITING CONCERN FOR POTENTIAL FIRE SPREAD. ALSO, GUSTY WINDS
ARE LESS OF A CONCERN FOR THE SATURDAY MORNING THUNDERSTORMS AS
THEIR BASES WILL BE MUCH HIGHER. BECAUSE OF THE COMBINATION OF
ALL OF THESE FACTORS, THERE IS LIMITED CONCERN FOR RAPID SPREAD
OF FIRE IF LIGHTNING DOES IGNITE NEW FIRES. THEREFORE, A RED
FLAG WARNING HAS NOT BEEN ISSUED SINCE CONDITIONS ARE NOT
REACHING CRITICAL, THOUGH THERE IS STILL AN ELEVATED CONCERN AS
LIGHTNING CAN STILL STRIKE DRY FUELS OUTSIDE OF AREAS THAT HAVE
RECEIVED RAIN. -03
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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