681
FXUS66 KPQR 200458
AFDPQR
AREA FORECAST DISCUSSION... UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
958 PM PDT MON OCT 19 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
LARGELY DRY WEATHER EXPECTED THROUGH MIDWEEK. NEAR
NORMAL TEMPERATURES TODAY WILL WARM ABOVE AVERAGE TUESDAY AND
WEDNESDAY. CHANCES FOR WETTER AND COOLER WEATHER RETURN LATE IN
THE WEEK WITH POTENTIAL FOR A MORE ROBUST SYSTEM NEXT WEEKEND.
DISCUSSION...NOW THROUGH SUNDAY
AN UPPER-LEVEL TROUGH OVER
THE NORTHEAST PACIFIC IS TAKING ON AN ELONGATED APPEARANCE IN
SATELLITE IMAGERY AS IT BEGINS TO CUTOFF FROM THE MEAN FLOW. THE
DEVELOPING UPPER LOW IS CENTERED NEAR 44.5N/131.5W AS OF MIDDAY
MONDAY, OR JUST OVER 350 MILES WEST OF NEWPORT, AND IS EXPECTED
TO TRACK SOUTH OFF THE CALIFORNIA COAST THROUGH TONIGHT. A
NARROW BAND OF CLOUDS WITHIN A DEFORMATION ZONE ON THE EASTERN
FLANK OF THE TROUGH IS CONTINUING TO PRODUCE MODEST RADAR
RETURNS EAST OF THE CASCADE CREST, HOWEVER OBSERVATIONS OF RAIN
REACHING THE SURFACE HAVE BEEN FEW AND FAR BETWEEN. AS THIS
FEATURE PIVOTS WEST, THERE ARE LOW CHANCES, 10-20%, OF LIGHT
RAIN IN THE LINN AND LANE COUNTY CASCADES THROUGH THIS EVENING.
OTHERWISE, DRY CONDITIONS ARE EXPECTED THROUGH AT LEAST
THURSDAY. UPPER-LEVEL RIDGING DEVELOPING OVER TOP OF THE CLOSED
LOW WILL SUPPORT OFFSHORE FLOW, ALTHOUGH THE MAGNITUDE OF THE
PRESSURE GRADIENT SHOULD NOT BE ENOUGH TO YIELD IMPACTFUL WINDS.
NONETHELESS, TYPICALLY WINDY SPOTS IN THE WESTERN COLUMBIA GORGE
AND NEAR EXPOSED RIDGES IN THE CASCADES WILL LIKELY SEE PERIOD
OF BREEZY EAST WINDS, ESPECIALLY OVERNIGHT AND IN THE EARLY
MORNING. THIS OFFSHORE FLOW WILL ALSO SUPPORT TEMPERATURES
REACHING AROUND 10 DEGREES ABOVE NORMAL TUESDAY AND WEDNESDAY,
TRANSLATING TO AFTERNOON HIGHS IN THE 60S ON THE COAST AND IN
TERRAIN, AND IN THE LOW TO MID 70S WITHIN INLAND VALLEYS.
THERE CONTINUES TO BE GOOD CONSENSUS THAT PROGRESSIVE TROUGHING
WILL RETURN TO THE REGION THURSDAY INTO FRIDAY, WHILE THE UPPER
LOW ALSO MOVES INLAND OVER CALIFORNIA SUPPORTING MOISTURE
TRANSPORT ABOUT ITS EASTERN FLANK AND INTO CENTRAL OREGON. THIS
COMBINATION WILL SUPPORT MODEST PRECIPITATION CHANCES AS HIGH AS
25-50% IN THE LANE AND LINN COUNTY CASCADES, BUT MORE WIDESPREAD
CHANCES OF 10-15%. WHERE RAIN DOES FALL, IT WILL LIKELY BE VERY
LIGHT AND FAIL TO AMOUNT TO SIGNIFICANT ACCUMULATIONS. THE
APPROACHING TROUGH WILL ALSO RESTORE ONSHORE FLOW AND SEE
TEMPERATURES FALL BACK TO MORE SEASONABLE VALUES FROM THURSDAY
THROUGH THE WEEKEND.
UNCERTAINTY IN THE FORECAST INCREASES THIS WEEKEND AS LONG-RANGE
GUIDANCE REMAINS MIXED ON THE EVOLUTION OF YET ANOTHER TROUGH
OVER THE GULF OF ALASKA. MOST ENSEMBLE MEMBERS DEPICT AN
OCCLUDING SURFACE LOW APPROACHING THE COAST SOMEWHERE BETWEEN
FLORENCE AND CAPE FLATTERY AT THE NORTHWESTERN TIP OF THE
OLYMPIC PENINSULA, WITH SOME THEN BRINGING THE SYSTEM INLAND
WHILE OTHERS SEE IT FILL AND RETROGRADE OVER THE WATERS OFF
WASHINGTON STATE. THE INTENSITY OF THIS LOW ALSO REMAINS IN
QUESTION, WITH A LOW TO MODERATE CHANCE OF DEEPENING TO AROUND
990 HPA OR LOWER. IMPACTS FROM THIS SYSTEM MAY BE TWO-FOLD:
THERE IS POTENTIAL FOR WIDESPREAD RAINFALL AND STRONG WINDS
CANNOT BE RULED OUT. IN TERMS OF RAINFALL, EASTWARD MOISTURE
TRANSPORT ON THE SOUTHERN FLANK OF THE LOW COULD AMOUNT TO THE
FIRST ATMOSPHERIC RIVER OF THE SEASON, HOWEVER THE DURATION OF
THE MOISTURE FLUX AS WELL AS THE MOISTURE FLUX MAGNITUDE DO NOT
AT THIS POINT APPEAR SUFFICIENT TO YIELD PRECIPITATION TOTALS
WHICH WOULD RAISE FLOODING CONCERNS AS AREA RIVERS REMAIN NEAR
ANNUAL MINIMUM STREAMFLOW THANKS TO A LARGELY DRY OCTOBER THUS
FAR. IF THE SURFACE LOW BECOMES DEEP ENOUGH AND APPROACHES NEAR
ENOUGH TO THE COAST, COASTAL COMMUNITIES MAY EXPERIENCE STRONG
WINDS. AT THIS POINT, THE CHANCES FOR PEAK WIND GUSTS OF 40 MPH
OR HIGHER AT THE COAST ON SATURDAY ARE 15-25%.
AVIATION...THROUGH 06Z WEDNESDAY
AT 05Z TUE, SATELLITE IMAGERY
INDICATES A BAND OF BKN TO OVC MID TO HIGH LEVEL CLOUDS ALONG AND
EAST OF INTERSTATE 5 DUE TO A LOW PRESSURE SYSTEM DROPPING SOUTHWARD
WELL OFFSHORE. THIS CLOUD COVER WILL BECOME MORE WIDESPREAD ACROSS
NW OR AND SW WA OVER THE NEXT FEW HOURS, THEN WILL BECOME MORE
SCATTERED AFTER 12-15Z TUE AS THE LOW PRESSURE SYSTEM CONTINUES
MOVING EAST. THESE HIGH CLOUDS SHOULD PREVENT FOG AND LOW STRATUS
DEVELOPMENT TUESDAY MORNING. CONFIDENCE IS HIGH (>90% CHANCE) FOR
PREDOMINANTLY VFR FLIGHT CONDITIONS THROUGH THE TAF PERIOD. WINDS
WILL REMAIN LIGHT TONIGHT LESS THAN 5-10 KT AT MOST TERMINALS,
THOUGH DEVELOPING OFFSHORE FLOW AND EASTERLY WINDS OVER THE CASCADES
WILL CAUSE AN INCREASE IN WINDS THROUGH THE WESTERN COLUMBIA RIVER
GORGE WITH GUSTS UP TO 25 KTS. OFFSHORE FLOW CONTINUES TO INCREASE
AFTER 15-18Z TUESDAY, BRINGING INCREASING EASTERLY WINDS TO KTTD AND
PORTLAND METRO TERMINALS AND INCREASING NORTHEAST WINDS TO KUAO.
WINDS WILL INCREASE OUT OF THE NORTH FROM KSLE TO KEUG. STRONGEST
WINDS WILL BE AT KTTD AND EAST INTO THE GORGE WITH GUSTS UP TO 25
KTS AT KTTD AND UP TO 30-35 KTS THROUGH THE WESTERN GORGE.
ELSEWHERE, WINDS WILL BE LIGHTER UP TO 8-10 MPH.
KPDX AND APPROACHES...VFR FLIGHTS CONDITIONS WILL CONTINUE THROUGH
THE TAF PERIOD WITH BKN HIGH CLOUDS TONIGHT, SCATTERING AFTER 12-15Z
TUE. NORTHWEST WINDS AROUND 5 KT INTO TUESDAY MORNING. EASTERLY
WINDS ARE EXPECTED TO DEVELOP AT KPDX AROUND 18-20Z TUESDAY,
SUSTAINED AROUND 8-11 KT WITH OCCASIONAL GUSTS UP TO 22 KTS. WINDS
BEGIN DECREASING AFTER 00-02Z WED. -03
MARINE
A LOW PRESSURE SYSTEM DROPPING SOUTHWARD WELL OFFSHORE
WILL GENERATE A STRONGER WESTERLY SWELL ARRIVING THIS EVENING
WHICH WILL PUSH SEAS TO NEAR 10 FT, HIGHEST BEYOND 10-20 NM
OFFSHORE WHERE A SMALL CRAFT ADVISORY IS IN EFFECT STARTING AT 5
PM TODAY.
WINDS TURN NORTHERLY AFTER SUNSET TODAY AND INCREASE NOTICEABLY
TONIGHT IN THE WAKE OF THE PASSING SYSTEM. WIDESPREAD WIND GUSTS
UP TO 25 KT WILL BE POSSIBLE OVER THE OUTER WATERS BEYOND 10 NM
OFFSHORE LATE TONIGHT INTO TOMORROW AFTERNOON. ALTHOUGH WAVE
HEIGHTS WILL BE ON THE DECREASE TOMORROW, THE INCREASE IN WIND
SPEEDS WILL MAINTAIN HAZARDOUS CONDITIONS FOR SMALL CRAFT.
THEREFORE, THE SMALL CRAFT ADVISORY IN EFFECT FOR THE OUTER
WATERS BEGINNING AT 5 PM TODAY WILL REMAIN IN EFFECT THROUGH 5
PM TOMORROW. BEYOND 5 PM TOMORROW, WINDS AND SEAS WILL BE ON THE
DECREASE AS HIGH PRESSURE RETURNS.
WINDS AND SEAS ARE SET TO INCREASE AGAIN THURSDAY INTO FRIDAY
MORNING WITH THE PASSAGE OF A WEAK COLD FRONT, ESPECIALLY OVER
THE NORTHERN WATERS TO THE NORTH OF CAPE FALCON WHERE
CONDITIONS WILL LIKELY BE HAZARDOUS TO SMALL CRAFT. THERE IS THE
POTENTIAL FOR A STRONGER LOW PRESSURE SYSTEM OVER THE UPCOMING
WEEKEND, BRINGING A 20-40% CHANCE FOR GALE FORCE WIND GUSTS AND
SEAS OVER 10 FEET. OVERALL CONFIDENCE IN THE EXACT TRACK AND
STRENGTH OF THIS POTENTIAL LOW PRESSURE SYSTEM IS LOW AT THIS
TIME, AND THE FORECAST IS WORTH MONITORING OVER THE NEXT SEVERAL
DAYS. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 PM PDT TUESDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page