844
FXUS66 KPQR 021208
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
408 AM PST MON MAR 2 2026
SYNOPSIS
HIGH PRESSURE OVER THE AREA TODAY WILL BRING
SEASONABLY WARM AND DRY CONDITIONS. THE NEXT FRONTAL SYSTEM
ARRIVES TUESDAY, BRING WIDESPREAD RAIN AND CASCADE SNOW THROUGH
WEDNESDAY, FOLLOWED BY SHOWERS WEDNESDAY NIGHT INTO THURSDAY.
ANOMALOUSLY STRONG HIGH PRESSURE LIKELY DEVELOPS OVER THE NE
PACIFIC OCEAN LATER THIS WEEK, THOUGH MOISTURE RIDING OVER THE
RIDGE WILL MAINTAIN CHANCES FOR PRECIPITATION THROUGH THE END OF
THE WEEK AND INTO THE WEEKEND.
DISCUSSION...NOW THROUGH SATURDAY
SATELLITE AND RADAR IMAGERY
AS OF EARLY MONDAY MORNING DEPICTS OVERCAST SKIES AND DECREASING
SHOWERS ACROSS THE LINN/LANE COUNTY CASCADES AS A AN UPPER-
LEVEL LOW PRESSURE SYSTEM MOVES INTO NORTHERN CALIFORNIA AND
SOUTHERN OREGON. SHOWERS WILL CONTINUE TO DECREASE THIS MORNING
AS THIS SYSTEM PROGRESSES FURTHER INTO THE GREAT BASIN AND
WEAKENS.
WEAK, TRANSIENT RIDGING MOVES OVER THE PACIFIC NORTHWEST TODAY,
RETURNING DRIER CONDITIONS TO MOST OF THE AREA. SLIGHTLY ABOVE
AVERAGE TEMPERATURES CONTINUE WITH HIGH TEMPERATURES FORECAST
NEAR 60 DEGREES AGAIN FOR INTERIOR LOWLAND VALLEYS. SKIES REMAIN
OVERCAST THIS MORNING, BUT BY THE AFTERNOON WE SHOULD SEE SOME
INCREASING CLOUD BREAKS. WHILE CONDITIONS WILL BE PREDOMINATELY
DRY, THERE IS STILL A 20-40% CHANCE FOR RESIDUAL SHOWERS ALONG
THE COAST AND OVER HIGHER TERRAIN. TONIGHT, THE UPPER RIDGE
QUICKLY SHIFTS EAST OF THE CASCADES AS MOIST SOUTHWESTERLY FLOW
DEVELOPS ACROSS THE REGION AHEAD OF THE NEXT SYSTEM.
TUESDAY, AN UPPER-LEVEL TROUGH APPROACHES AND PRECIPITATION
CHANCES INCREASE THROUGHOUT THE DAY FROM WEST TO EAST. HOWEVER,
ANY RAIN THAT DOES FALL LIKELY REMAINS LIGHT THROUGH TUESDAY
AFTERNOON. THE MAJORITY OF ENSEMBLE MEMBERS (>90%) SUGGEST THAT
MORE WIDESPREAD, SUBSTANTIAL RAIN WILL ARRIVE TUESDAY NIGHT INTO
WEDNESDAY AS THE UPPER TROUGH PUSHES A COLD FRONT ACROSS THE
REGION. CHANCES FOR LIQUID PRECIPITATION EXCEEDING 1 INCH ENDING
BETWEEN 4 PM TUESDAY TO 4 PM THURSDAY ARE AROUND 10-20% ALONG
THE I-5 CORRIDOR FROM COWLITZ TO LANE COUNTY, 40-60% ALONG THE
COAST, AND 50-80% FOR THE COAST RANGE AND CASCADES. AT THIS
POINT, NOT EXPECTING WIND IMPACTS WITH THIS SYSTEM, THOUGH COULD
SEE SOME SOUTHWESTERLY WIND GUSTS UP TO 25-30 MPH ALONG THE
COAST AND INLAND, WITH LOCALLY STRONGER GUSTS OVER HIGHER
TERRAIN AS THE FRONT PASSES THROUGH ON WEDNESDAY. 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%.
POTENTIAL FOR ADVISORY-LEVEL SNOW ALSO RETURNS TO THE CASCADE
PASSES AS SNOW LEVELS DROP TO AROUND 3500-4500 FEET ON
WEDNESDAY. THE BULK OF THE SNOW IS EXPECTED BETWEEN 4 AM
WEDNESDAY TO 4 AM THURSDAY, WITH HIGHEST SNOWFALL RATES LIKELY
OCCURRING WEDNESDAY MORNING WHEN TEMPERATURES ARE COLDEST.
CHANCES FOR 6+ INCHES OF SNOW DURING THIS 24 HOUR PERIOD ARE
AROUND 70-80% ALONG THE SANTIAM AND WILLAMETTE PASSES AND 25%
FOR HIGHWAY 26 AT GOVERNMENT CAMP. SINCE WE'LL BE IN MILD
ONSHORE FLOW, SNOW WOULD MOST LIKELY BE WET AS TEMPERATURES ARE
MARGINALLY FREEZING ALONG SANTIAM AND WILLAMETTE PASSES (850 MB
TEMPS AROUND 0 TO -1 DEG C WEDNESDAY MORNING). SNOW AMOUNTS
APPEAR LOWER NORTH OF SANTIAM PASS AS TEMPERATURES ARE LOOKING A
FEW DEGREES ABOVE FREEZING. THOSE PLANNING TO TRAVEL THROUGH
THE CASCADES MID-WEEK SHOULD CHECK ROAD CONDITIONS BEFORE
LEAVING AND CARRY AN EMERGENCY SUPPLY KIT.
THURSDAY THROUGH THE WEEKEND, THE MAJORITY OF ENSEMBLE MEMBERS
SUGGEST ANOMALOUS, BROAD UPPER-LEVEL RIDGING OFFSHORE OVER THE
NORTHEAST PACIFIC. THE OFFSHORE PLACEMENT OF THIS RIDGE WILL NOT
BE 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 5-10%, HIGHEST
TO THE NORTH. -10/DH
AVIATION
SATELLITE IMAGERY AND TERMINAL OBSERVATIONS AS OF
EARLY MONDAY MORNING DEPICTS A MIX OF MVFR/VFR CIGS ACROSS
NORTHWEST OREGON AS AN UPPER LEVEL LOW PRESSURE SYSTEM MOVES
INTO NORTHERN CALIFORNIA AND SOUTHERN OREGON. RESIDUAL SHOWERS
SOUTH OF KSLE CONTINUE TO DECREASE AND WILL EVENTUALLY DRY OUT
LATER THIS MORNING. WILL SEE A MIX OF MVFR/LOW-END VFR CIGS FOR
MOST TERMINALS THROUGH 18Z MON. AN EXCEPTION WOULD BE THE
CENTRAL AND SOUTHERN WILLAMETTE VALLEY AND CENTRAL OREGON COAST
WHERE CIGS WILL TREND MORE LIFR/IFR GIVEN THE MORE MOIST SURFACE
CONDITIONS. HIGH PRESSURE ALOFT WILL HELP MAINTAIN LOW LEVEL
STRATUS THROUGH THE MORNING. CIGS TREND BACK TO VFR AFTER 18Z
MON WITH 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 VFR CIGS THROUGH THE TAF
PERIOD WITH INCREASING CLOUD BREAKS IN THE AFTERNOON AS HIGH
PRESSURE BUILDS. VARIABLE WINDS UNDER 5 KT. -10
MARINE
BENIGN CONDITIONS EXPECTED THROUGH TONIGHT. WINDS TURN
MORE SOUTHERLY ON MONDAY AHEAD OF THE NEXT SYSTEM, BUT REMAIN
LIGHT. SEAS REMAIN AROUND 3-4 FT AT 11-12. THE NEXT FRONTAL
SYSTEM ARRIVES ON TUESDAY, LIKELY RETURNING BREEZIER SOUTHERLY
WINDS. A SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR ALL WATERS
INCLUDING THE COLUMBIA RIVER BAR FROM 7 AM TUESDAY TO 4 AM
WEDNESDAY FOR SOUTHERLY WIND GUSTS UP TO 25 KT. SEAS WILL ALSO
GRADUALLY BUILD ON WEDNESDAY AND THURSDAY AS A WESTERLY SWELL
MOVES IN. CHANCES FOR SEAS EXCEEDING 10 FT ARE 40-60% DURING
THIS TIME, WITH THE HIGHEST CHANCES BEYOND 10-20 NM OFFSHORE.
-10
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 7 AM TUESDAY TO 4 AM PST WEDNESDAY FOR
PZZ210-251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
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