795
FXUS66 KPQR 191722 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1022 AM PDT THU MAR 19 2026
..UPDATED AVIATION DISCUSSION
SYNOPSIS
THE REGION REMAINS ON THE NORTHERN PERIPHERY OF AN
UPPER LEVEL RIDGE THROUGH FRIDAY, BRINGING MUCH WARMER THAN
NORMAL TEMPERATURES TO MOST OF NORTHWEST OREGON. MEANWHILE, A
WEAKENING ATMOSPHERIC RIVER AIMED AT WESTERN WASHINGTON AND
VANCOUVER ISLAND WILL OCCASIONALLY WOBBLE SOUTHWARD FROM TIME TO
TIME, BRINGING OCCASIONAL LIGHT RAIN DOWN TO THE NORTH OREGON
COAST AT TIMES WITH MORE PERSISTENT RAIN OVER PACIFIC, WAHKIAKUM,
AND NORTHERN COWLITZ/SKAMANIA COUNTIES. AS THE WEEKEND
APPROACHES, COOLER CONDITIONS WITH ISOLATED LIGHT SHOWERS ARE
EXPECTED THROUGH MONDAY. A PATTERN CHANGE IS ON THE HORIZON AS A
BROAD, LOW PRESSURE SYSTEM COMES DOWN FROM THE GULF OF ALASKA,
BRINGING WIDESPREAD RAIN WITH BREEZY SOUTH TO SOUTHWEST WINDS BY
TUESDAY. PRECIPITATION IN THE CASCADES ON TUESDAY WILL FALL AS
EITHER RAIN, SNOW, OR A RAIN/SNOW MIX DEPENDING ON SNOW LEVELS
(WHICH COULD RANGE ANYWHERE FROM 2000 TO 9000 FEET PER MODEL
SPREAD).
SHORT TERM...NOW THROUGH FRIDAY NIGHT
MINIMAL CHANGES IN THE
FORECAST FOR TODAY AS THE SYNOPTIC PATTERN REMAINS RATHER
STAGNANT. THE REGION IS STILL CAUGHT IN-BETWEEN TWO SIGNIFICANT
SYNOPTIC SCALE FEATURES, THOSE BEING A BROAD UPPER LEVEL RIDGE
CENTERED OVER THE GREAT BASIN AND A BROAD TROUGH OVER THE GULF
OF ALASKA, THIS SET UP IS MAINTAINING PERSISTENT WEST TO SOUTHWEST
FLOW ALOFT OVER THE PACIFIC NORTHWEST. SANDWICHED BETWEEN THESE
TWO FEATURES IS A WEAKENING ATMOSPHERIC RIVER (AR) POINTED
TOWARDS THE OLYMPIC PENINSULA AND VANCOUVER ISLAND AREA. OUR
REGION REMAINS ON THE FAR SOUTHERN END OF THE AR WHICH IS
MAINTAINING A BAND OF RAIN MAINLY IMPACTING PACIFIC AND
WAHKIAKUM COUNTIES AS WELL AS THE FAR NORTHERN OREGON COAST.
HI-RESOLUTION MODEL REFLECTIVITY CONTINUES TO SHOW THIS BAND OF
PRECIPITATION OCCASIONALLY MEANDERING TO THE SOUTH AND NORTH
WHICH DOES BRING LIGHT PRECIPITATION TO NORTHERN PORTIONS OF
COWLITZ AND SKAMANIA COUNTIES AND WELL AS FURTHER SOUTH ALONG
THE OREGON COAST THROUGH AT LEAST LATE TONIGHT.
THE AREAS MENTIONED ABOVE WILL ALSO REMAIN CLOUDY AND COOLER
WHEN COMPARED TO OTHER AREAS WITHIN OUR CWA. OTHER AREAS REMAIN
PARTLY TO MOSTLY SUNNY WHICH IS BRINGING WARMER DAYTIME HIGH
TEMPERATURES INTO THE UPPER 60S TO MID 70S, WITH THE MID 50S TO
MID 60S ALONG THE COAST. THE WARMEST TEMPERATURES ARE EXPECTED
OVER THE CENTRAL AND SOUTHERN WILLAMETTE VALLEY AND THE CASCADE
FOOTHILLS; NOTE RECENT SURFACE WEATHER OBSERVATIONS SHOW RELATIVE
HUMIDITIES FALLING INTO THE 20-40% RANGE OR LOWER IN THESE
AREAS DURING PEAK DAYTIME HEATING. THIS MEANS HUMIDITY LEVELS
ARE LOW AND THE AIRMASS REMAINS QUITE DRY TO THE SOUTH OF THE
AFOREMENTIONED BAND OF RAIN. THE NBMV5.0 WAS UTILIZED TO HELP
LOWER THE RELATIVE HUMIDITY FORECAST IN THESE AREAS.
AS FRIDAY APPROACHES, A PATTERN CHANGE IS ON THE HORIZON AS THE
TWO AFOREMENTIONED SYNOPTIC FEATURES PUSH EASTWARD. THE LOW
FROM THE GULF OF ALASKA WILL BRING WHAT REMAINS OF THE AR AS
WELL AS A COLD FRONT. THIS WILL BRING RELATIVELY COOLER
TEMPERATURES AS WELL AS RAIN TO MORE OF THE CWA. AS A RESULT,
DAYTIME HIGHS ON FRIDAY WILL GENERALLY BE IN THE 50S ALONG THE
COAST AND INTO THE 60S FOR INLAND LOCATIONS. EXPECT THE COOLEST
TEMPERATURES NORTH OF SALEM AND WARMEST SOUTH OF SALEM. THERE IS
ALSO A 55-85% CHANCE OF LIGHT RAIN SHOWERS ON FRIDAY AS THE
COLD FRONT MOVES THROUGH, WITH THE HIGHEST PROBABILITIES ALONG
THE COAST, NORTH OF THE PORTLAND/VANCOUVER METRO AREA AND IN THE
CASCADES. RAIN AMOUNTS ARE EXPECTED TO BE LIGHT WITH NO NOTABLE
IMPACTS TO DISCUSS. /42
LONG TERM...SATURDAY THROUGH WEDNESDAY
THE LONG TERM
FORECAST REMAINS HIGHLIGHTED BY A RELATIVELY COOLER WEATHER
PATTERN WITH SEASONABLE TEMPERATURES AND MAINLY DRY CONDITIONS,
EXCEPT TUESDAY AND WEDNESDAY WHEN WETTER CONDITIONS ARRIVE AS A
MORE ROBUST SYSTEM IS EXPECTED TO DIVE SOUTHWARD FROM THE
EASTERN PACIFIC. FOR THE SATURDAY THROUGH MONDAY TIME FRAME,
MODELS AND THEIR ENSEMBLES ARE IN GOOD AGREEMENT FOR NEARLY
ZONAL FLOW ALOFT WITH SURFACE HIGH PRESSURE IN PLACE ON THE EAST
SIDE OF THE CASCADES.
WITH THE START OF NEXT WEEK TAKEN CARE OF, LETS FOCUS ON THE
MIDDLE OF NEXT WEEK AS A ROBUST EASTERN PACIFIC SYSTEM MOVES
INTO THE PACIFIC NW. THIS SYSTEM LOOKS TO BRING 850 MB TEMPERATURES
FROM -8 TO 5 C (YES THAT IS THE SPREAD BETWEEN ENSEMBLES) ALONG
WITH WIDESPREAD RAIN. NBM PROBABILITIES FOR PRECIPITATION PICK
UP ON THIS WELL AND PEAK BETWEEN 65-90% BY TUESDAY EVENING/NIGHT.
ALTHOUGH CONFIDENCE IS HIGH PRECIPITATION WILL RETURN, CONFIDENCE
IS NOT AS HIGH REGARDING EXACT PRECIPITATION AMOUNTS AS MODEL
SPREAD FOR QPF IS LARGE. THE NBM 10TH PERCENTILE FOR 48-HOUR QPF
AMOUNTS FROM 5 AM TUESDAY TO 5 AM THURSDAY RANGES FROM AROUND
0.10-0.50 INCHES, WHILE THE NBM 90TH PERCENTILE RANGES FROM
1.15-3.70 INCHES (HIGHEST AMOUNTS AT THE COAST AND ACROSS THE
WESTERN SLOPES OF THE COAST RANGE AND CASCADES). REGARDLESS OF
THE EXACT OUTCOME, IT APPEARS FLOODING WILL NOT BE A CONCERN.
AS MENTIONED PREVIOUSLY, THE ALMOST 15 C DEGREE SPREAD WITHIN
THE ENSEMBLES FOR 850 MB TEMPERATURES, IS RESULTING IN A VERY
HIGH UNCERTAINTY IN SNOW LEVELS FOR TUESDAY AND WEDNESDAY. THE
NBM 10-90TH PERCENTILE FOR SNOW LEVELS DURING THAT TIME RANGES
FROM 2000-9000 FEET, RESPECTIVELY. THE MOST LIKELY OUTCOME IS
AROUND 2500-4500 FEET, HIGHEST OVER THE LANE AND LINN COUNTY
CASCADES AND LOWEST OVER THE SOUTH WASHINGTON CASCADES. AS SUCH,
IS NOT CLEAR YET WHETHER OR NOT THE CASCADES WILL SEE RAIN, A
RAIN/SNOW MIX, OR ACCUMULATING SNOW. IT IS ALSO NOT CLEAR YET IF
THE CASCADE PASSES WILL BE IMPACTED WITH ACCUMULATING SNOW.
CURRENT NBM PROBABILITIES FOR 6 INCHES OF SNOW OR MORE IN A
48-HOUR PERIOD ENDING 5 PM THURSDAY ARE QUITE LOW, AROUND 20% AT
PASS LEVEL. THIS WILL BE AN AREA OF FOCUS AS MORE DATA BECOMES
AVAILABLE. LASTLY, BREEZY SOUTH/SOUTHWEST WINDS ARE ALSO WORTH
KEEPING AN EYE ON, BUT CURRENT ENSEMBLE GUIDANCE HAS GUSTS
LIKELY STAYING BELOW 35 MPH WITH MINIMAL IMPACTS. /42
AVIATION
AN UPPER LEVEL RIDGE TO THE SOUTH AND A BROAD UPPER
LEVEL TROUGH OVER THE GULF OF ALASKA CONTINUES TO DIRECT AN
ATMOSPHERIC RIVER TOWARDS WESTERN WASHINGTON. THE SOUTHERN PORTION
OF THIS ATMOSPHERIC RIVER WILL BRING LIGHT RAIN SHOWERS ALONG THE
FAR NORTH OREGON COAST (KAST) THROUGHOUT THE TAF PERIOD. CAN'T RULE
OUT A FEW STRAY SHOWERS OR SPRINKLES OVER THE NORTHERN WILLAMETTE
VALLEY. HIGH CONFIDENCE (60-80% CHANCE) THAT MVFR CIGS PERSIST AT
KAST THROUGHOUT THE DAY, WHILE THERE IS MODERATE CONFIDENCE (30-50%
CHANCE) THAT LIFR STRATUS AT KONP DISSIPATES AND RETURNS VFR
CONDITIONS BY 19-21Z THU. HIGH PRESSURE ALOFT COULD EASILY KEEP THE
STRATUS BELOW 500 FEET AT KONP AS ONSHORE FLOW MAINTAINS MOIST
CONDITIONS.
MEANWHILE, VFR CONDITIONS PREVAIL FOR WILLAMETTE VALLEY TERMINALS
WITH HIGH LEVEL CLOUDS. CIGS ACROSS THE VALLEY WILL GRADUALLY DROP
TO AROUND 5 KFT OR LESS FRIDAY MORNING AS THE UPPER LEVEL RIDGE
SHIFTS EASTWARD AND TROUGHING ENTERS THE AREA. WINDS GENERALLY
SOUTHERLY TO SOUTHWESTERLY ACROSS THE AREA AND UNDER 10 KT, WITH
OCCASIONAL GUSTS UP TO 20 KT ALONG THE COAST.
KPDX AND APPROACHES...VFR CONDITIONS WITH HIGH CLOUDS THROUGHOUT THE
TAF PERIOD. CIGS BEGIN TO GRADUALLY FALL TO LOW-END VFR AFTER 09-12Z
FRI AS THE UPPER LEVEL RIDGE SHIFTS EASTWARD. SOUTHERLY TO
SOUTHEASTERLY WINDS UNDER 10 KT. -10
MARINE
LOW PRESSURE OFFSHORE WILL MAINTAIN BREEZY SOUTHERLY
WINDS THROUGH LATE TONIGHT/EARLY FRIDAY MORNING, MAINLY FOR THE
WATERS NORTH OF CAPE FALCON INCLUDING THE COLUMBIA RIVER BAR. A
SMALL CRAFT ADVISORY HAS BEEN ISSUED FOR THESE AREAS THROUGH 5 AM
FRIDAY FOR SOUTHERLY WINDS WITH GUSTS UP TO 25 KT. WINDS REMAIN
WEAKER SOUTH OF CAPE FALCON. SEAS AROUND 7-9 FT AT 10-11 SEC
THROUGH FRIDAY. ALSO, FOR THE COLUMBIA RIVER BAR, WE ARE ENTERING
A STRONG TO VERY STRONG EBB CYCLE THROUGH AT LEAST THE WEEKEND.
A BROAD, UPPER LEVEL LOW AND ASSOCIATED WEAK SURFACE COLD FRONT
WILL RESULT IN WINDS BECOMING NORTHERLY BY SATURDAY AND REMAINING
UNDER 20 KT. SEAS ALSO GRADUALLY FALL TOWARDS 5-7 FT AT 10-12 SEC.
BENIGN MARINE CONDITIONS CONTINUE THROUGH MONDAY BEFORE ANOTHER,
MORE ROBUST SYSTEM RETURNS TUESDAY/WEDNESDAY. THIS SYSTEM WILL
BRING A RETURN OF STRONGER SOUTHERLY WINDS ACROSS ALL WATERS.
CURRENT GUIDANCE SUGGESTS A 60-80% CHANCE FOR WIDESPREAD, SMALL
CRAFT WIND GUSTS OF 25 KT OR GREATER AND A 40-60% CHANCE FOR GALE
GUSTS OF 35 KT OR GREATER ON TUESDAY. SEAS ON TUESDAY AND
WEDNESDAY ARE ALSO EXPECTED TO BUILD IN RESPONSE TO INCREASING
WIND WAVES AND LOOK TO BUILD TOWARDS 11-13 FT. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 5 AM PDT FRIDAY FOR
PZZ210-251-271.
WWW.WEATHER.GOV/PORTLAND
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