902
FXUS66 KPQR 250412 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
911 PM PDT TUE MAR 24 2026
SYNOPSIS
WIDESPREAD RAIN AND LOCALLY BREEZY TO WINDY
CONDITIONS CONTINUE THIS AFTERNOON BEFORE WE TRANSITION TO
SHOWERS FOR WEDNESDAY. MOUNTAIN SNOWFALL RETURNS TO THE PASSES
AS WELL BEFORE ALL LINGERING PRECIPITATION TAPERS OFF EARLY
THURSDAY MORNING. HIGH CONFIDENCE IN THE RETURN OF DRY WEATHER
ACCOMPANIED BY A WARMING TREND LATE WEEK INTO THE WEEKEND.
CHANCES ARE INCREASING FOR ANOTHER WEATHER SYSTEM LATE WEEKEND
INTO EARLY NEXT WEEK, ALTHOUGH THE EXACT DETAILS OF THIS EVENT
REMAIN UNCERTAIN AT THIS TIME.
DISCUSSION...NOW THROUGH MONDAY
CURRENT SATELLITE AND RADAR
OBSERVATIONS THIS AFTERNOON SHOW A COLD-FRONTAL BOUNDARY
SWINGING THROUGH THE REGION WITH WIDESPREAD RAINFALL ONGOING,
ALTHOUGH THIS WILL BEGIN TO CHANGE HEADED INTO THE EVENING
HOURS. WINDS, WHICH RECENTLY PEAKED ALONG THE COAST, HAVE BEEN
BREEZY TO LOCALLY WINDY (GUSTS GENERALLY 40-55MPH) WITH A FEW OF
THE MOST EXPOSED SURFACE OBSERVATIONS LIKE CAPE DISAPPOINTMENT
AND CLATSOP SPIT HAVING SEEN GUSTS 55-65MPH RANGE. HOWEVER,
INLAND WINDS HAVE BEEN MUCH LIGHTER COMPARATIVELY AND LIKELY
REMAIN THAT WAY - GUSTS CONTINUE IN THE 20-35 MPH RANGE FOR A
FEW MORE HOURS BEFORE RAMPING DOWN THIS EVENING. OVERALL THIS
FRONTAL FEATURE REMAINS RATHER PROGRESSIVE, QUICKLY PUSHING TO
OUR EAST THIS EVENING FOLLOWED BY A TRANSITION TO A SHOWERY,
COOLER, AND SLIGHTLY UNSETTLED POST-FRONTAL AIRMASS OVERNIGHT.
FOR WEDNESDAY OUR ATTENTION TURNS TO A SECONDARY UPPER-LEVEL
SHORTWAVE FEATURE EXPECTED TO PUSH INTO THE PACIFIC NORTHWEST
DURING THE MIDDAY AND AFTERNOON HOURS HELPING TO FURTHER, ALBEIT
TEMPORARILY, ENHANCE SHOWER ACTIVITY. DUE TO DAYTIME HEATING
AND THE COLDER AIRMASS ALOFT, DETERMINISTIC MODEL SOUNDINGS DO
INDICATE SOME WEAK INSTABILITY (100-250J/KG MUCAPE) DURING THE
AFTERNOON HOURS WHICH IF FULLY UTILIZED COULD PRODUCE A WEAK
THUNDERSTORM WITH INFREQUENT LIGHTNING, SMALL HAIL, AND LOCALLY
GUSTY WINDS THE MAIN IMPACTS. ALL IN ALL, CHANCES REMAIN RATHER
LOW FOR ANY GIVEN LOCATION (5-15%) TO EXPERIENCE ONE OF THESE
WEAK "ONE-HIT-WONDERS". ONCE WE APPROACH SUNSET AND DAYTIME
HEATING WANES, ANY THREAT FOR THIS ACTIVITY COMES TO AN END.
FOR ALL THE MOUNTAIN SNOWFALL ENJOYERS OUT THERE, SNOW LEVELS
FINALLY DROP BELOW THE CASCADE PASSES TONIGHT INTO EARLY
WEDNESDAY MORNING ONCE WE'VE FULLY TRANSITIONED TO THE
AFOREMENTIONED POST-FRONTAL AIRMASS. UNFORTUNATELY, THE SAD
STATE OF OUR SNOWPACK WON'T RECEIVE MUCH HELP AS THE SHOWERY
NATURE OF THE PRECIPITATION FROM THIS POINT ONWARD WILL LIMIT
OUR SNOWFALL ACCUMULATION POTENTIAL. THE LATEST NBM
PROBABILITIES OF AT LEAST 6 INCHES OF SNOW OVER THE CASCADES
(BOTH OR AND SW WA) REMAINS LESS THAN 5-15%, EXCEPT FOR THE
HIGHEST PEAKS. SNOW LEVELS LIKELY LOWER TO 1500-2000 FT FOR A
BRIEF PERIOD WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING AS
SHOWERS ARE ENDING, WITH A 5-10% CHANCE OF SNOW LEVELS FALLING
NEAR VALLEY FLOOR IN THE SOUTHWEST WASHINGTON LOWLANDS.
HOWEVER, PRECIPITATION PROBABILITIES ALONG WITH AMOUNTS ARE SO
LOW BY THIS POINT THAT EVEN IF SOME WET SNOW DOES MIX IN, IT
WOULD NOT ACCUMULATE OR LEAD TO ANY IMPACTS, ESPECIALLY AS ROAD
SURFACES WOULD BE TOO WARM.
ON THURSDAY THE SHORTWAVE MOVES EAST OF THE AREA WITH UPPER
LEVEL FLOW BECOMING MORE ZONAL BEHIND IT. GENERALLY ZONAL FLOW
WITH SLIGHT RIDGING CONTINUES FRIDAY INTO SATURDAY, BRINGING DRY
CONDITIONS WITH CLEARING SKIES. EXPECT A WARMING TREND WITH
DAYTIME TEMPERATURES IN THE MID TO UPPER 50S ON THURSDAY, LOW
TO MID 60S FRIDAY, AND MID TO UPPER 60S ON SATURDAY/SUNDAY FOR
THE INTERIOR LOWLANDS. OVER THE WEEKEND HITTING AND/OR EXCEEDING
70 DEGREES REMAINS WITHIN THE REALM OF POSSIBILITY BUT
PROBABILITIES HAVE DECREASED A FEW PERCENTAGE POINTS COMPARED
TO YESTERDAY. THE LATEST NBM INDICATES A 20-50% CHANCE FOR HIGH
TEMPERATURES TO MEET OR EXCEED 70 DEGREES ACROSS THE PORTLAND
METRO AREA AND WILLAMETTE VALLEY BOTH SATURDAY AND SUNDAY, WITH
SLIGHTLY HIGHER PROBABILITIES (40-50%) SOUTH OF SALEM NEAR
EUGENE.
BOTH DETERMINISTIC AND ENSEMBLE GUIDANCE STILL INDICATE A DEEP
TROUGH MOVING EAST OVER THE PACIFIC AND APPROACHING THE WEST
COAST LATER ON SUNDAY INTO MONDAY, BRINGING INCREASING CHANCES
OF PRECIPITATION. HOWEVER, THERE STILL REMAINS MUCH TO BE
DESIRED REGARDING THE EXACT TIMING, AMPLITUDE, AND THUS IMPACTS
WITH THIS DISTURBANCE - MODEL UNCERTAINTY REMAIN HIGH
SUNDAY/MONDAY. THIS UNCERTAINTY CONTINUES TO FACILITATE A
SIGNIFICANT NBM 25TH-75TH PERCENTILE TEMPERATURE SPREAD, SHOWING
HIGHS RANGING FROM THE UPPER 50S TO THE MID 70S FOR THE
INTERIOR LOWLANDS SUNDAY AFTERNOON DEPENDING ON HOW QUICKLY THE
NEXT SYSTEM ARRIVES. SHOULD ENSEMBLE GUIDANCE TREND SLOWER WITH
THE DEEP TROUGH OFFSHORE, SUNDAY MAY END UP BEING THE WARMEST
DAY OF THE UPCOMING LATE WEEK/WEEKEND TIME PERIOD. HOPEFULLY
WE'LL SEE FORECAST SOLUTIONS CONVERGE IN THE COMING DAYS. -99/03
AVIATION
THE FRONTAL SYSTEM THAT BROUGHT WIDESPREAD RAIN AND
MVFR CONDITIONS HAS ALL BUT EXITED THE AREA LEAVING IN IT'S WAKE
MOIST AIR WITH VFR CIGS. SOME AREAS OF MVFR CONDITIONS REMAIN THIS
EVENING, AND THERE WILL BE POCKETS, ESPECIALLY IN THE SOUTHERN
WILLAMETTE VALLEY WHERE THE FRONT HASN'T FULLY EXITED YET. WILL
HAVE TO MONITOR FOR THE PRESENCE OF FOG FORMATION TONIGHT WITH THE
LINGERING MOISTURE FROM THE RAIN. LUCKILY, CONDITIONS BEHIND THE
FRONT WILL MIX, BUT IT MAY NOT BE SIGNIFICANT ENOUGH. CANNOT RULE
OUT AREAS OF PATCHY FOG IN SOME OF THE RURAL AREAS AND IN THE
CASCADE VALLEYS WITH SOME MODELS SHOWING GREATER THAN A 20%
CHANCE. A BREAK IN THE RAIN WILL BE FOLLOWED BY A SHORT WAVE
TROUGH THAT WILL BRING AROUND AROUND A 20% CHANCE OF RAIN SHOWERS
AND THUNDERSTORMS IN THE AFTERNOON. THUNDERSTORM CHANCES ARE GOING
TO BE CONCENTRATED INLAND AND TO THE NORTH. THERE ARE SOME
COMPONENTS MISSING IN THE PATTERN TO INCLUDE PROB30S FOR TS IN
THE TAFS, BUT CANNOT RULE OUT SMALL HAIL, BREEZY OUTFLOW WINDS,
AND MAYBE A RUMBLE HERE OR THERE AFTER 21Z WED.
KPDX AND APPROACHES...VFR CONDITIONS THROUGH THE NEXT 24 HOURS
WITH ISOLATED SHOWERS AFTER 20Z WED WITH A PASSING SYSTEM. AROUND
A 15-30% CHANCE OF IFR VIS IN FOG BETWEEN 10-16Z WED BUT IF
MIXING REMAINS THOSE CHANCES WILL BE FAR LOWER AND MAY REMAIN IN
THE VICINITY OF THE TERMINAL. 10-20% CHANCE OF TS BETWEEN 18Z WED
AND 00Z THU. -27
MARINE
SOUTHERLY GALES ARE EXPECTED TO EASE BY 5 PM THIS
EVENING AS A COLD FRONT PUSHES INLAND. BREEZY SOUTHWEST WINDS WILL
CONTINUE WITH GUSTS UP TO 25 KT ACROSS THE COASTAL WATERS THROUGH
WEDNESDAY MORNING. ANOTHER LOW PRESSURE SYSTEM WILL PUSH A WEAK
COLD FRONT ACROSS THE WATERS LATER WED MORNING, FOLLOWED BY MORE
WESTERLY ONSHORE FLOW EASING THROUGH WED NIGHT.
AS OF EARLY TUESDAY AFTERNOON, COMBINED SEAS AT AROUND 13 TO 14
FT CONTINUE TO BUILD IN RESPONSE TO THE STRONG SOUTHERLY WINDS,
PRODUCING STEEP AND CHOPPY SEAS WITH A PERIOD OF 8 TO 9 SECONDS.
BUOY 46089 IS REPORTING SEAS OF AROUND 18 FT AT 11 SECONDS,
INDICATING THE ARRIVAL OF A FRESH SOUTHWESTERLY SWELL. LOCAL
GUIDANCE SUGGESTS SEAS SHOULD BUILD TO AROUND 17 FT AT BUOY 46029
LATER THIS AFTERNOON. SEAS THEN ARE EXPECTED TO GRADUALLY SUBSIDE
TONIGHT THROUGH WEDNESDAY, THOUGH WILL LIKELY REMAIN ELEVATED
ABOVE 9 TO 10 FT THROUGH WED AFTERNOON. WILL MAINTAIN THE
HAZARDOUS SEAS WARNING FOR THE NORTHERN COASTAL WATERS THROUGH
THIS EVENING, FOLLOWED BY SMALL CRAFT ADVISORIES THROUGH
WEDNESDAY.
HIGH PRESSURE THEN BUILDS OVER THE WATERS ON THURSDAY. NORTHERLY
WINDS RETURN THROUGH FRIDAY AS A SURFACE THERMAL TROUGH
STRENGTHENS ALONG THE COAST. SEAS GENERALLY REMAIN AROUND 7 TO 8
FT. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...HAZARDOUS SEAS WARNING UNTIL 11 PM PDT THIS EVENING FOR PZZ210-
251-271.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO NOON PDT
WEDNESDAY FOR PZZ210.
SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 5 PM PDT
WEDNESDAY FOR PZZ251-271.
SMALL CRAFT ADVISORY UNTIL 5 PM PDT WEDNESDAY FOR PZZ252-253-272-
273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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