881
FXUS66 KPQR 170508 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
908 PM PST SUN FEB 16 2025
UPDATED AVIATION DISCUSSION.
SYNOPSIS
A LOW PRESSURE SYSTEM WILL MAINTAIN WIDESPREAD RAIN
AND CASCADE SNOW THROUGH MONDAY. HEAVY SNOW AND HAZARDOUS
TRAVEL IS EXPECTED FOR THE CASCADE PASSES THROUGH MONDAY
AFTERNOON. MILDER TEMPERATURES CONTINUE THROUGH THE WEEK, WITH
ANOTHER WEATHER SYSTEM ARRIVING LATER TUESDAY INTO WEDNESDAY.
LIKELY TRENDING DRIER AND WARMER LATER THIS WEEK, BUT POTENTIAL
FOR HEAVIER RAIN RETURNS FOR THE WEEKEND.
SHORT TERM...NOW THROUGH WEDNESDAY NIGHT
NOW THROUGH
WEDNESDAY...SATELLITE IMAGERY THIS AFTERNOON SHOWS A LOW
PRESSURE SYSTEM SPINNING OFFSHORE NEAR VANCOUVER ISLAND. MOIST,
ONSHORE FLOW WILL MAINTAIN RAIN SHOWERS ACROSS THE AREA, WITH
SNOW ACCUMULATING IN THE CASCADES ABOVE 3500 FEET. CURRENTLY,
SNOW LEVELS ARE HOVERING RIGHT AROUND PASS LEVEL (BETWEEN
4000-5000 FT) WITH TEMPERATURES AROUND 32-34 DEGREES. WEB CAMS
SHOW MOSTLY BARE OR SLUSHY ROADS AT CASCADE PASSES, BUT THAT
SHOULD CHANGE AS TEMPERATURES COOL LATER TODAY AND SNOW LEVELS
FALL TO 3500 FT OVERNIGHT. STILL EXPECTING AROUND 1 TO 2 FEET OF
SNOW TO FALL THROUGH MONDAY AFTERNOON. HEAVIEST SNOWFALL RATES
ARE EXPECTED THIS EVENING THROUGH MONDAY MORNING AS A SHORTWAVE
TROUGH MOVES ACROSS THE REGION, WITH HREF SUGGESTING RATES OF UP
TO 1 INCH PER HOUR DURING THIS PERIOD, WHILE NBM GUIDANCE ALSO
SHOWS A 70-80% CHANCE OF EXCEEDING 12 INCHES OF SNOW AT PASS
LEVEL THROUGH 4PM MONDAY. THEREFORE, HAVE EXTENDED THE WINTER
STORM WARNING THROUGH MONDAY AFTERNOON IN COORDINATION WITH
NEIGHBORING FORECAST OFFICES. THOSE TRAVELING THROUGH THE
CASCADES SHOULD PREPARE FOR WINTER WEATHER AND REFER TO
ODOT/WSDOT FOR THE LATEST ROAD CONDITIONS AND RESTRICTIONS.
ELSEWHERE, EXPECT THE GLOOMY, RAINY WEATHER TO CONTINUE THROUGH
MONDAY, WITH DISSIPATING SHOWERS BY LATE AFTERNOON/EVENING. HAVE
SEEN UP TO 1.50-2.00 INCHES OF RAINFALL DURING THE PAST 24 HOURS
OVER PARTS OF THE COAST RANGE AND CASCADE FOOTHILLS. EXPECT AN
UPTICK IN PRECIP AMOUNTS FOR THE NEXT 24-HOURS WITH AROUND 1 TO 3
INCHES OF RAINFALL POSSIBLE IN THE HIGHER TERRAIN. ALTHOUGH RIVERS
ARE ON THE RISE, THERE ARE STILL NO HYDRO IMPACTS EXPECTED.
WILL SEE A BRIEF BREAK IN THE WET WEATHER THROUGH AT LEAST TUESDAY
MORNING FOR MOST AREAS AS AN UPPER SHORTWAVE TROUGH PASSES ACROSS
THE REGION. WITH HIGH PRESSURE AND LOW LEVEL MOISTURE OVER THE AREA,
WILL LIKELY SEE LOW STRATUS OR FOG SETTLE IN OVERNIGHT INTO TUESDAY
MORNING WITH LOW TEMPERATURES IN THE UPPER 30S TO LOWER 40S.
OFFSHORE WINDS WILL INCREASE ON TUESDAY WITH TEMPERATURES WARMING
INTO THE LOWER 50S. THE NEXT FRONTAL SYSTEM WILL PUSH A WARM FRONT
ACROSS THE AREA LATER TUESDAY, PUSHING SNOW LEVELS BACK UP OVER 4000
TO 6000 FT. RAIN SPREADS BACK ACROSS THE AREA BY TUESDAY EVENING.
WILL ALSO MENTION THERE IS AROUND A 30-50% CHANCE OF A WINTRY MIX OF
SNOW/SLEET RETURNING TO THE UPPER HOOD RIVER VALLEY TUESDAY NIGHT
INTO WED MORNING AS TEMPERATURES ARE FORECAST TO COOL TO AROUND 30-
34 DEG. THE NBM SUGGESTS THERE IS A 10-20% CHANCE FOR 1 INCH OR MORE
OF SNOW THERE.
WILL NEED TO CLOSELY MONITOR THIS WEATHER SYSTEM FOR A POTENTIALLY
STRONGER LOW SPINNING UP NEAR THE COAST LINE WEDNESDAY MORNING.
WHILE LATEST MODEL GUIDANCE DOESN'T SUGGEST THE LOW DEEPENS MUCH
(990 TO 995 MB), THERE IS AROUND A 20% CHANCE OF WIND GUSTS
EXCEEDING 50 MPH ALONG THE COAST. OTHERWISE, ANOTHER MILD, RAINY DAY
WITH ANOTHER ROUND OF HIGHER CASCADE SNOW THROUGH WED EVENING. /DH
LONG TERM...THURSDAY THROUGH SUNDAY
MODELS AND THEIR ENSEMBLES
ARE IN GOOD AGREEMENT LATER THIS WEEK OF UPPER LEVEL RIDGING
BUILDING OVER THE REGION. MOST CLUSTERS KEEP THE AREA DRY MUCH OF
THURSDAY AND FRIDAY, ALTHOUGH THERE IS AROUND A 30-40% CHANCE THAT A
FRONT IS ABLE TO PUSH RAIN BACK INTO SOUTHWEST WASHINGTON AND FAR NW
OREGON BY FRIDAY AFTERNOON. TEMPERATURES ARE LIKELY TO CONTINUE THE
GRADUAL WARMING TREND INTO THE MID TO UPPER 50S INTO THE WEEKEND.
THE NEXT WEATHER SYSTEM THAT BRINGS MORE RAIN TO THE PACIFIC NW OVER
THE WEEKEND WILL LIKELY BE ASSOCIATED WITH A WEAK TO MODERATE
ATMOSPHERIC RIVER, WITH POTENTIAL PWAT AMOUNTS OF OVER AN INCH AS
INDICATED BY THE EUROPEAN ENSEMBLE, THOUGH DETAILS OF WHERE THE BAND
OF HEAVIER MOISTURE SETS UP IS STILL QUITE UNCERTAIN. /DH
AVIATION
SATELLITE, RADAR, AND SURFACE OBSERVATIONS AS OF 445Z
MONDAY DEPICT RAIN CONTINUING TO PUSH ONSHORE AND A MIXED BAG OF
IFR, MVFR AND VFR CIGS. MVFR CIGS WERE MOST PREVALENT INLAND
AROUND THE PORTLAND/VANCOUVER METRO. EXPECT WIDESPREAD IFR TO MVFR
CIGS TO CONTINUE THROUGHOUT THE TAF PERIOD AT ALL TERMINALS,
ASIDE FROM BRIEF PERIODS OF VFR CONDITIONS. MVFR PROBS ALONG THE
COAST ARE GENERALLY +80% THROUGH MONDAY MORNING WITH IFR PROBS
FLUCTUATING BETWEEN 30-60%. PROBS FOR MVFR CIGS INLAND ARE
GENERALLY 40-80% BUT COULD BE A LITTLE MORE SPORADIC BETWEEN
SHOWERS. STRATIFORM PRECIP IS EXPECTED TO CONTINUE THIS
EVENING/NIGHT BEFORE BECOMING SHOWERY AGAIN MONDAY MORNING.
EASTERLY WINDS AROUND KTTD CONTINUE BUT GUSTS ARE STARTING TO WANE
LATE THIS EVENING. WOULD EXPECT WINDS TO FINALLY SHIFT SOUTHERLY
OVER THE NEXT COUPLE OF HOURS(6-9Z). ELSEWHERE, WINDS ARE ALREADY
OUT OF THE SOUTH TO SOUTHWEST AROUND 10 KT.
PDX AND APPROACHES...FREQUENT RAIN SHOWERS WILL CONTINUE
THROUGHOUT THE TAF PERIOD WITH PERSISTENT LOW-END MVFR CIGS, ASIDE
FROM BRIEF PERIODS OF VFR CIGS BETWEEN SHOWERS. CIGS COULD
BRIEFLY LOWER TO HIGH-END IFR THRESHOLDS AT TIMES, ESPECIALLY WITH
HEAVIER SHOWERS THAT MOVE OVER THE TERMINAL. SOUTHEAST WINDS
AROUND 10 KT SHOULD BECOME SOUTHERLY BY 08Z MONDAY. -BATZ/TK
MARINE
SOUTHWEST WINDS WILL GRADUALLY WEAKEN SUNDAY NIGHT
INTO MONDAY, WITH GUSTS LIKELY FALLING BELOW 20 KT BY LATE
MONDAY MORNING. HOWEVER, SEAS WILL INCREASE DURING THAT TIME DUE
TO AN INCOMING WESTERLY SWELL. EXPECT SEAS AROUND 10 FT AT 10
TO 12 SECONDS ON SUNDAY, BECOMING 12 TO 14 FT AT 14 TO 15
SECONDS SUNDAY NIGHT INTO MONDAY. HIGH PRESSURE WILL THEN BRING
A BRIEF LULL IN WINDS WITH SUBSIDING SEAS MONDAY NIGHT INTO
TUESDAY, WITH SEAS FALLING TO AROUND 10 FT AT 12 TO 13 SECONDS.
ANOTHER FRONTAL SYSTEM ARRIVES TUESDAY NIGHT INTO WEDNESDAY
MORNING, BRINGING ANOTHER ROUND OF INCREASED WINDS AND BUILDING
SEAS. FORECAST WIND SPEEDS WITH THIS SYSTEM HAVE INCREASED A BIT
COMPARED TO YESTERDAY'S FORECAST, WITH FORECAST WIND GUSTS NOW UP
TO 40 KT OVER THE OUTER WATERS AND UP TO 35 KT OVER THE INNER
WATERS. THE PROBABILITY FOR MAX WIND GUSTS OVER 35 KT RANGES
BETWEEN 70-90%, HIGHEST OVER THE OUTER WATERS. GIVEN THESE HIGH
PROBABILITIES AND INCREASING CONFIDENCE, A GALE WATCH WILL LIKELY
BE NEEDED WITH FUTURE FORECAST UPDATES UNLESS FORECAST WIND SPEEDS
TREND DOWNWARD. -TK
PQR WATCHES/WARNINGS/ADVISORIES
OR...WINTER STORM WARNING UNTIL 4 PM PST MONDAY FOR ORZ126>128.
WA...WINTER STORM WARNING UNTIL 4 PM PST MONDAY FOR WAZ211.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST MONDAY FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 4 AM PST TUESDAY FOR PZZ251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
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