452
FXUS66 KPQR 192331
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
331 PM PST WED FEB 19 2025
SYNOPSIS
FRONTAL SYSTEM CONTINUES TO SHIFT EAST WITH POST
FRONTAL SHOWERS OVER THE NEXT 24 HOURS. CASCADE SNOW WILL
DISSIPATE AS SNOW LEVELS RISE AND PRECIPITATION LESSENS. RAIN
CHANCES REMAIN ALONG THE COAST AND INLAND. A SERIES OF WEATHER
SYSTEMS MOVE IN THROUGH THE WEEKEND WITH HEAVY RAINFALL.
SHORT TERM...NOW THROUGH FRIDAY
SATELLITE SHOWS THE FRONTAL
BAND FROM THE RAINY SYSTEM SHIFTING EASTWARD THIS AFTERNOON,
WITH SHOWERY CONDITIONS OFFSHORE. SHOWERS WILL PERSIST THROUGH
THE DAY WITH SNOW FALLING ALONG THE CASCADES. AN ADDITIONAL 1-3
INCHES OF SNOW IS EXPECTED, THOUGH IT WILL NOT OCCUR DURING THE
DAY AS TEMPERATURES ARE WELL ABOVE FREEZING. SNOW RATIOS ARE
GOING TO BE QUITE LOW THOUGH AS SNOW LEVELS RISE. THIS MEANS
THAT SNOW THAT DOES FALL WILL BE ON THE WETTER SIDE AND THUS
TRUE ACCUMULATION MAY BE DIFFICULT. SNOW AT THE PASS LEVEL IS
EXPECTED.
TRANSITIONING INTO THURSDAY AND FRIDAY, CONDITIONS BECOME MUCH
MORE SETTLED WITH A TRANSIENT RIDGE MOVING OVERHEAD. SOME
LINGERING SHOWERS EARLY THURSDAY. EASTERLY WINDS WILL RETURN
WHICH WILL USHER IN DRIER AIR, CLEARER SKIES, AND COLDER
TEMPERATURES. OVERNIGHT THURSDAY INTO FRIDAY MORNING,
TEMPERATURES WILL BE THE LOWEST OF THE WEEK DUE TO A COMBINATION
OF EASTERLY WINDS AND RADIATIONAL COOLING FROM CLEARER
SKIES. COULD SEE SOME AREAS OF PATCHY FOG, IN AREAS THAT REMAIN
ABOVE FREEZING, AND NEAR THE COAST RANGE AND THE SOUTHERN
WILLAMETTE VALLEY WHERE WIND SPEEDS WILL BE LOWER. -MUESSLE
LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
SATURDAY IS WHEN
THE WEATHER BEGINS TO TURN AS A SERIES OF FRONTAL SYSTEMS MAKE
THEIR WAY TOWARDS THE PACIFIC NORTHWEST. GLOBAL MODELS ARE IN
FAIRLY GOOD AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN, BUT
DISAGREE IN REGARDS TO THE EXACT TRACK AND IMPACTS OF THE RAIN.
THE FIRST SYSTEM ARRIVES FRIDAY NIGHT AS A NORTHEAST PACIFIC
LOW ADVECTS DOWN THE COASTLINE FROM THE GULF OF ALASKA TO
VANCOUVER ISLAND. THIS COLD AIR WRAPPED LOW WILL NOT NECESSARILY
BE AS IMPACTFUL TO OUR AREA, BUT WILL BRING WITH IT
PRECIPITATION AND WILL AID IN BREAKING DOWN THE RIDGE. MOST RAIN
WILL FALL TO OUR NORTH.
THE NEXT SYSTEM IS MUCH MORE ROBUST AS A TRAILING WARM FRONT ADVECTS
IN. THIS FRONT WILL BE MUCH WETTER AND POTENTIALLY MORE
IMPACTFUL IN THE LONG RUN. THIS FRONT WILL START MOVING INLAND
ON SATURDAY AFTERNOON, THEN INTENSIFY AS THE BULK OF THE
MOISTURE SHIFTS SOUTHWARD NEARLY DIRECTLY OVER THE FORECAST
AREA. LOOKING AT THE GLOBAL CLUSTER ANALYSIS THERE IS STILL
QUITE A BIT OF UNCERTAINTY IN THE OVERALL MOISTURE INVOLVED IN
THIS SYSTEM. FOR EXAMPLE, THE ECMWF IS TRENDING WETTER, WHILE
THE GFS AND CANADIAN ARE MUCH DRIER. IN TILLAMOOK, THE 24-HR
RAINFALL TOTALS ENDING AT 7AM SUNDAY RANGE FROM A 5% CHANCE OF
0.5 INCH, TO A 5% CHANCE OF GREATER THAN 3.5 INCHES. IN
ADDITION, SOME MODELS ARE SUGGESTING A "RAIN SHADOW" EFFECT
WHICH WOULD KEEP THE WILLAMETTE VALLEY SLIGHTLY DRIER THAN THE
COAST RANGE AND CASCADES.
ON SUNDAY, THERE IS A SECOND SURGE OF PRECIPITATION THOUGH IT
MAY NOT BE AS IMPACTFUL AS THE SATURDAY SYSTEM. HOWEVER, THE
COMBINATION OF THE TWO WILL MAKE FOR A VERY WET WEEKEND. IN THE
48 HOURS COVERING BOTH SATURDAY AND SUNDAY, RAINFALL TOTALS WILL
RANGE IN THE "INCHES". FOR EXAMPLE, WITHIN THE COAST RANGE,
THERE IS AROUND AN 80% CHANCE OF 3 INCHES OR MORE OF RAIN, AND
NEARLY A 25% CHANCE OF 5 INCHES OR MORE. THE WILLAMETTE VALLEY
IN CONTRAST HAS LESS THAN A 5% CHANCE OF 3 INCHES OF RAIN. WITH THIS
AMOUNT OF PRECIPITATION, WILL NOT BE SURPRISED IF WE GET SOME
LOCALIZED RIVER FLOODING ALONG THE COAST. SNOW LEVELS WILL RISE
UP TO 6500-7000 FT SO DON'T EXPECT A DUMPING OF SNOW THIS
WEEKEND. ULTIMATELY, THERE IS A GREAT AMOUNT OF UNCERTAINTY IN
REGARDS TO WHERE THIS SYSTEM WILL END UP, AND JUST HOW WET IT
WILL BE. -MUESSLE
AVIATION
COVERAGE OF RAIN SHOWERS CONTINUES TO TREND DOWNWARD,
YIELDING SOME CONTINUED MVFR CIGS WITH CLOUD BASES AT 1-3 KFT BUT
UNRESTRICTED VIS AT BOTH INLAND AND COASTAL TERMINALS. SHOWERS
WILL FURTHER DIMINISH BY 02-03Z THU, WITH CIGS TRENDING TOWARD
VFR ACROSS THE REGION ASIDE FROM AST/ONP WHERE ONSHORE FLOW WILL
SEE PERSISTENT MVFR CIGS. GUSTY EAST WINDS AT TTD WILL FINALLY
GIVE WAY TO SOUTHWESTERLY FLOW BY 03-05Z THU, WHILE WEST TO
SOUTHWEST FLOW AT 5-10 KT WILL CONTINUE ELSEWHERE. ANOTHER WEAK
BATCH OF RAIN SHOWERS MAY AFFECT COASTAL TERMINALS AFTER 09-12Z
THU, BUT CONFIDENCE IN ANY IMPACTS TO FLYING CONDITIONS IS LOW.
OTHERWISE, VFR CONDITIONS ARE EXPECTED TO PREVAIL ON THURSDAY.
PDX AND APPROACHES...CURRENT MVFR/LOW-VFR CIGS ARE EXPECTED TO
TREND TOWARD VFR AS RAIN SHOWERS EXIT EASTWARD BY 03Z THU WITH
UNRESTRICTED VIS THROUGHOUT THE PERIOD. EASTERLY WINDS HAVE BEGUN
TO TURN BEHIND THE DEPARTING FRONTAL SYSTEM, WITH SOUTH TO
SOUTHWEST FLOW AT 5-10 KT DEVELOPING THIS AFTERNOON AND CONTINUING
THROUGH THURSDAY. -PICARD
MARINE
A FRONTAL SYSTEM TRACKING INLAND FROM THE NORTHEAST
PACIFIC WILL CONTINUE TO YIELD DIMINISHING WESTERLY WINDS THROUGH
TONIGHT. GALE WARNINGS HAVE THEREFORE BEEN CANCELLED AND REPLACED
WITH SMALL CRAFT ADVISORIES FOR BOTH INNER AND OUTER WATERS
THROUGH 4 AM THURSDAY. SEAS OF 12-14 FT WILL SUBSIDE TO 8-10 FT
BY THURSDAY MORNING, CONTINUING THROUGH THURSDAY NIGHT.
ANOTHER FRONTAL SYSTEM WILL APPROACH THE WATERS FRIDAY INTO
SATURDAY, ALTHOUGH SOME UNCERTAINTY REMAINS IN THE POTENTIAL TRACK
AND INTENSITY OF THIS LOW. CONFIDENCE IN THE OCCURRENCE OF
SOUTHERLY GALE-FORCE WINDS SATURDAY OR SATURDAY NIGHT IS
INCREASING, CURRENTLY ASSESSED AS A 70-90 PERCENT LIKELIHOOD.
THERE IS CONTINUED MODERATE CONFIDENCE IN MAXIMUM GUSTS EXCEEDING
STORM-FORCE, ASSESSED AT 50-60% LIKELIHOOD AT THIS LEAD TIME. SEAS
LOOK TO SIMILARLY BUILD TO 12-14 FT, WHILE THERE IS A 25% CHANCE
SIGNIFICANT WAVE HEIGHTS EXCEED 15 FT. SEAS OF 9-12 FT THEN LOOK
TO CONTINUE THROUGH AT LEAST MONDAY. -PICARD
PQR WATCHES/WARNINGS/ADVISORIES
OR...WINTER WEATHER ADVISORY UNTIL 4 AM PST THURSDAY FOR ORZ126>128.
WA...WINTER WEATHER ADVISORY UNTIL 4 AM PST THURSDAY FOR WAZ211.
PZ...SMALL CRAFT ADVISORY UNTIL 1 AM PST THURSDAY FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 4 AM PST THURSDAY FOR PZZ251>253-
271>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