993
FXUS66 KPQR 020558 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
957 PM PST SUN MAR 1 2026
..UPDATED AVIATION DISCUSSION
SYNOPSIS
A LOW PRESSURE SYSTEM MOVING INTO NORTHERN CALIFORNIA
WILL MAINTAIN RAIN SHOWERS ACROSS SOUTHERN PARTS OF THE FORECAST
AREA THROUGH TONIGHT, WITH SNOW CONFINED TO THE HIGHEST CASCADE
PEAKS. SEASONABLY WARM AND DRY CONDITIONS EXPECTED ON MONDAY AS HIGH
PRESSURE MOVES OVER THE REGION. THE NEXT FRONTAL SYSTEM ARRIVING
LATER TUESDAY WILL BRING MORE WIDESPREAD VALLEY RAIN AND CASCADE
SNOW THROUGH WEDNESDAY, FOLLOWED BY SHOWERS LATER WED AFTERNOON.
ANOMALOUSLY STRONG HIGH PRESSURE LIKELY DEVELOPS OVER THE NE PACIFIC
LATER THIS WEEK, THOUGH THE POSITION OF THIS RIDGE WILL DETERMINE IF
STORMS RIDING OVER THE RIDGE WILL BE ABLE TO IMPACT OUR REGION. THIS
UNCERTAINTY MAINTAINS CHANCES FOR PRECIPITATION THROUGH THE END OF
THE WEEK INTO NEXT WEEKEND.
DISCUSSION...NOW THROUGH SATURDAY
SATELLITE AND RADAR IMAGERY
THIS AFTERNOON REVEALS A LOW PRESSURE SYSTEM OFF THE NORTHERN
CALIFORNIA COAST SPREADING CLOUDS AND LIGHT RAIN SHOWERS NORTHWARD
INTO PARTS OF NW OREGON. THE MAJORITY OF RAIN SHOWERS ACROSS THE
FORECAST AREA ARE EXPECTED TO CONTINUE ACROSS MUCH OF LANE COUNTY
THROUGH THIS EVENING, WHILE THE NORTHERN PERIPHERY OF THE RAIN
LIKELY EXTENDS AS FAR NORTH AS LINN, BENTON, AND LINCOLN COUNTIES.
THERE IS AROUND A 30-40% (OR LESS) CHANCE OF A FEW SPRINKLES FROM
SALEM NORTHWARD, WITH MOST OF SW WASHINGTON EXPECTED TO REMAIN DRY
THROUGH TONIGHT. HIGHEST RAINFALL AMOUNTS ARE EXPECTED OVER THE
CENTRAL OREGON CASCADES AND FOOTHILLS ACROSS LINN AND LANE COUNTIES
DUE TO OROGRAPHIC ENHANCEMENTS AS THE UPPER LOW PUSHES INLAND OVER
NORTHERN CALIFORNIA TONIGHT. MEAN 24-HOUR QPF AMOUNTS RANGE FROM
0.50 TO 1.0 INCH, ALTHOUGH NBM PROBS SUGGEST THERE IS AROUND A 15-
35% CHANCE FOR RAINFALL TOTALS TO EXCEED 1 INCH. THIS COULD OCCUR
WITH ANY HEAVIER SHOWERS THAT DEVELOP. SNOWFALL IS NOT EXPECTED AT
CASCADE PASSES AS SNOW LEVELS SITTING AT AROUND 7000 FT ARE NOT
EXPECTED TO FALL BELOW 6000 FT TONIGHT.
WEAK, TRANSIENT RIDGING MOVES ACROSS THE PACIFIC NW ON MONDAY
RETURNING MOST OF THE AREA TO DRIER CONDITIONS. SLIGHTLY ABOVE
AVERAGE TEMPERATURES CONTINUE, ALTHOUGH SKIES ARE LIKELY TO REMAIN
MOSTLY CLOUDY TO PARTLY SUNNY. A FEW LIGHT SHOWERS WILL BE POSSIBLE
(15-30% CHANCE) AT THE COAST AND OVER HIGHER TERRAIN ON MONDAY. BY
TUESDAY, THE UPPER RIDGE SHIFTS EAST OF THE CASCADES AS MOIST
SOUTHWEST FLOW DEVELOPS ACROSS THE REGION. PRECIPITATION CHANCES
WILL INCREASE THROUGH THE DAY FROM WEST TO EAST, BUT ANY RAIN THAT
DOES FALL LIKELY REMAINS LIGHT THROUGH TUESDAY AFTERNOON.
MORE SUBSTANTIAL RAINS ARRIVES LATER TUESDAY NIGHT INTO WEDNESDAY AS
AN UPPER LEVEL TROUGH PUSHES A COLD FRONT ACROSS THE REGION. CHANCES
FOR EXCEEDING 1 INCH OF PRECIPITATION THROUGH WEDNESDAY NIGHT ARE
HIGHEST ACROSS THE TERRAIN (65-95%), WHILE THERE IS AROUND A 30-60%
CHANCE ALONG THE COAST, AND 5-25% CHANCE THROUGH THE INLAND VALLEYS.
NO WIND IMPACTS EXPECTED, THOUGH COULD SEE SOUTHERLY WINDS GUSTING
UP TO 30-35 MPH AT THE COAST AND UP TO 25 MPH INLAND AS THE FRONT
PUSHES INLAND LATE TUE NIGHT/EARLY WED MORNING. BY WEDNESDAY
AFTERNOON, COOLER AIR ALOFT ASSOCIATED WITH THE UPPER TROUGH MAY
ALLOW FOR SOME DEEPER SHOWERS TO DEVELOP, BUT CHANCES FOR
THUNDERSTORMS REMAINS CAPPED AT AROUND 10-15%.
SNOW LEVELS ARE ALSO EXPECTED TO DROP TO AROUND 4000 FT ON
WEDNESDAY, BRINGING POTENTIAL FOR ADVISORY LEVEL SNOWFALL TO THE
CASCADE PASSES. CHANCES FOR 6+ INCHES OF SNOWFALL IN 24-HOURS AT THE
SANTIAM AND WILLAMETTE PASSES IS AROUND 50%, WITH HIGHEST SNOWFALL
RATES LIKELY OCCURRING WEDNESDAY MORNING. THOSE PLANNING TO TRAVEL
THROUGH THE CASCADES MID-WEEK SHOULD CHECK ROAD CONDITIONS BEFORE
LEAVING AND CARRY AN EMERGENCY SUPPLY KIT.
THURSDAY TO SATURDAY, THERE REMAINS SOME UNCERTAINTY WITH THE UPPER
LEVEL PATTERN OVER THE REGION, BUT THE MAJORITY OF ENSEMBLE MEMBERS
SUGGEST ANOMALOUS, BROAD UPPER LEVEL RIDGING OFFSHORE OVER THE
NORTHEAST PACIFIC. THE OFFSHORE PLACEMENT OF THIS RIDGE IS NOT
FAVORABLE FOR A RETURN TO DRY AND SUNNY WEATHER. MOST ENSEMBLE
GUIDANCE SUGGESTS THAT MOISTURE WILL RIDE THE NORTHERN OR EASTERN
PERIPHERY OF THE RIDGE AND TRACK TOWARDS THE PACIFIC NORTHWEST,
MAINTAINING CHANCES FOR PRECIPITATION THROUGH THE END OF THE WEEK.
THOUGH MEAN QPF AMOUNTS REMAIN RELATIVELY LIGHT, THERE ARE A FEW
SCENARIOS WHERE MORE SUBSTANTIAL PRECIPITATION OCCURS, BUT CHANCES
FOR THOSE IS CURRENTLY AROUND 10-20%, HIGHEST TO THE NORTH. DH/10
AVIATION
SATELLITE IMAGERY AND TERMINAL OBSERVATIONS AS OF
LATE SUNDAY EVENING DEPICTS A MIX OF MVFR/VFR CIGS ACROSS NORTHWEST
OREGON AS A LOW PRESSURE SYSTEM MOVES INTO NORTHERN CALIFORNIA AND
SOUTHERN OREGON. SHOWERS SOUTH OF KSLE FROM THIS LOW ARE BEGINNING
TO DECREASE OVER OUR AREA, EVENTUALLY DRYING OUT COMPLETELY BY 12Z
MON. HIGH CONFIDENCE (>80% CHANCE) FOR MVFR CIGS CONTINUING THROUGH
18Z MON ACROSS ALL TERMINALS AS CONDITIONS MOISTEN OVERNIGHT. THERE
IS ALSO A 40-60% CHANCE FOR IFR CIGS AT ANY GIVEN HOUR BETWEEN 12-
18Z MON FOR THE CENTRAL/SOUTHERN WILLAMETTE VALLEY AND CENTRAL
OREGON COAST. THE HIGHEST CHANCES FOR IFR CIGS OR LOWER WILL BE AT
KEUG, WHERE SURFACE CONDITIONS ARE THE MOST MOIST FROM TODAY'S
SHOWERS. HIGH PRESSURE RE-BUILDS ON MONDAY WITH CIGS TRENDING BACK
TO VFR AFTER 18Z MON. SHOULD BEGIN TO SEE INCREASING CLOUD BREAKS
AFTER 21Z MON-00Z TUE.
VARIABLE WINDS GENERALLY UNDER 5 KT EXCEPT FOR LIGHT EAST WINDS
THROUGH THE COLUMBIA RIVER GORGE AND FAR EAST PORTLAND METRO AREA.
KPDX AND APPROACHES...PREDOMINATELY MVFR CIGS THROUGH 18Z MON, THEN
IMPROVING TO VFR IN THE AFTERNOON WITH INCREASING CLOUD BREAKS AS
HIGH PRESSURE BUILDS. VARIABLE WINDS UNDER 5 KT. -10
MARINE
BENIGN CONDITIONS EXPECTED THROUGH MONDAY NIGHT. SURFACE
HIGH PRESSURE OFFSHORE AND A WEAK THERMAL TROUGH ALONG THE COAST
WILL MAINTAIN NORTHEASTERLY WINDS 5-10 KT ACROSS THE WATERS TODAY.
SEAS FALL TO 3-4 FT AT 9-10 SEC TONIGHT INTO MONDAY. WINDS TURN MORE
SOUTHERLY ON MONDAY AHEAD OF THE NEXT SYSTEM, BUT REMAIN LIGHT. THE
NEXT FRONTAL SYSTEM ARRIVES ON TUESDAY, LIKELY RETURNING SMALL CRAFT
CONDITIONS. THERE IS A 60-80% CHANCE FOR FREQUENT AND WIDESPREAD
SOUTHERLY WIND GUSTS OF 22 KT OR GREATER ACROSS THE WATERS ON
TUESDAY. SEAS WILL ALSO GRADUALLY BUILD ON WEDNESDAY AND THURSDAY AS
A WESTERLY SWELL MOVES IN. CHANCES FOR SEAS EXCEEDING 10 FT ARE 30-
50% DURING THIS TIME, WITH THE HIGHEST CHANCES BEYOND 10-20 NM
OFFSHORE. -19/10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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