032
FXUS66 KPQR 260402 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
901 PM PDT MON MAR 25 2019
UPDATED AVIATION AND MARINE SECTIONS
SYNOPSIS
GENERALLY COOL AND SHOWERY WEATHER WILL PERSIST OVER
NORTHWEST OREGON AND SOUTHWEST WASHINGTON THIS WEEK EXCEPT FOR
TUESDAY AND SATURDAY, WHICH WILL STAND THE BEST CHANCE OF ENDING UP
DRY.
SHORT TERM...TODAY THROUGH THURSDAY
VISIBLE SATELLITE IMAGERY
THIS AFTERNOON SHOWS A SURFACE LOW PRESSURE OFF THE PACIFIC NORTHWEST
COAST. AN OCCLUDED FRONT IS CURRENTLY IN THE PROCESS OF MOVING ACROSS
WESTERN OREGON. THIS IS RESULTING IN WIDESPREAD LIGHT RAIN FALLING
ACROSS NORTHWEST OREGON AND SOUTHWEST WASHINGTON. AS COLDER AIR ALOFT
FILTERS OVER THE REGION THIS AFTERNOON, EXPECT THE LOWER TO MIDDLE
PART OF THE ATMOSPHERE TO DESTABILIZE AND PRECIPITATION TO TURN MORE
SHOWERY IN NATURE. THERE REMAINS A CHANCE THIS DESTABILIZATION ALOFT
WILL COUPLE AT LEAST BRIEFLY WITH DAYTIME HEATING TO ALLOW A STRONG
SHOWER OR TWO TO POP BETWEEN 4-7 PM, PARTICULARLY ACROSS THE CENTRAL
AND SOUTHERN WILLAMETTE VALLEY. SHEAR PROFILES SUGGEST THERE COULD BE
A LOW END WIND THREAT IF SOMETHING DEVELOPS. MODEL SOUNDINGS APPEAR A
BIT BETTER FOR THUNDER CHANCES OVER THE WATERS, BUT THE CONTINUED
LACK OF SUSTAINED CONVECTION UPSTREAM SUGGESTS THIS REMAINS A LOW
THREAT AS WELL.
GIVEN THERE SHOULD BE AT LEAST SOME CLEARING OVERNIGHT AND WITH
WEAKENING SURFACE WINDS, SOME PATCHY FOG SHOULD DEVELOP LATE TONIGHT
INTO TUESDAY MORNING IN THE VALLEYS OF THE COAST RANGE AND IN THE
WILLAMETTE AND LOWER COLUMBIA RIVER VALLEYS. WEAK SHORTWAVE RIDGING
WILL PUSH ACROSS THE REGION ON TUESDAY, WHICH SHOULD LEAD TO A
MAINLY DRY DAY ACROSS THE AREA WITH TEMPERATURES TOPPING OUT AROUND
60F.
HOWEVER, THE AFOREMENTIONED SURFACE LOW PRESSURE CURRENTLY FOUND OFF
THE OREGON COAST WILL DUMBBELL AROUND ITSELF AND EVENTUALLY MOVE
CLOSE ENOUGH TO BRING ANOTHER ROUND OF RAIN SPREADING
NORTH-NORTHEASTWARD ACROSS THE REGION ON WEDNESDAY. DEPENDING ON THE
TRACK OF THE SURFACE LOW PRESSURE, WE COULD SEE ADDITIONAL SHOWERS
LINGER INTO WEDNESDAY NIGHT, BUT GENERALLY WE SHOULD SEE A REDUCTION
OF RAIN CHANCES WITH THE LOSS OF DAYTIME HEATING. WITH THE COOL UPPER
LEVEL TROUGH STILL OVERHEAD ON THURSDAY, WE SHOULD SEE SHOWER
ACTIVITY INCREASE IN COVERAGE AND INTENSITY DURING THE AFTERNOON AND
EARLY EVENING HOURS ONCE AGAIN. /NEUMAN
LONG TERM...THURSDAY NIGHT THROUGH MONDAY
MODELS ARE IN GOOD
AGREEMENT THE SHORTWAVE TROUGH BRINGING SHOWERS TO THE AREA ON
WEDNESDAY AND THURSDAY WILL BE SLOWLY EXITING THE REGION ON FRIDAY.
THIS SHOULD BRING A BIT MORE SUNSHINE TO THE AREA, BUT THERE MAY YET
BE ANOTHER ROUND OF AFTERNOON AND EARLY EVENING SHOWERS ON FRIDAY,
PARTICULARLY FOR AREAS AWAY FROM THE COAST AND ACROSS THE HIGHER
TERRAIN. MODELS AND THEIR ENSEMBLES ARE IN FAIR AGREEMENT SHORTWAVE
RIDGING WILL MOVE OVER THE PACIFIC NORTHWEST SOMETIME SATURDAY. THIS
SHOULD LEAD TO A MAINLY DRY DAY WITH LOWLAND LOCATIONS LIKELY RISING
WELL INTO THE 60S SATURDAY AFTERNOON. MODELS THEN SUGGEST THE
SHORTWAVE RIDGE WILL SHIFT EAST OF THE REGION SATURDAY NIGHT INTO
SUNDAY AND OPEN THE DOOR TO INCREASINGLY MOIST SOUTHWESTERLY FLOW.
THIS WILL LIKELY RESULT IN ANOTHER FRONTAL STORM SYSTEM BRINGING
ANOTHER ROUND OF COOL AND SHOWERY WEATHER TO THE AREA SUNDAY AND/OR
MONDAY, BUT TIMING UNCERTAINTY REMAINS. AS A RESULT, POPS WERE
INCREASED TO NEAR OR ABOVE CLIMATOLOGY PER A BLEND OF MODEL AND
ENSEMBLE GUIDANCE. /NEUMAN
AVIATION
THE OCCLUDED FRONT MOVED NORTH INTO WA LATE THIS
AFTERNOON. POST FRONTAL SHOWERS WILL CONTINUE THIS EVENING WITH A
MIX OF VFR AND MVFR CONDITIONS. SHOWERS WILL EASE OVERNIGHT WITH
A WEAK SURFACE RIDGE DEVELOPING OVER WESTERN OREGON. A BIT OF A
CHALLENGE FOR LATE TONIGHT WITH REGARDS TO CIGS AND VIS, BUT
THINK THERE WILL BE ENOUGH MOISTURE MORE STABLE CONDITIONS FOR
MVFR CIGS TO DEVELOP. ALSO MAY SEE IFR CIGS AND VIS DEVELOP AS
WELL BUT DO NOT EXPECT IT TO BE WIDESPREAD. MODELS INDICATE THE
AIR MASS DRYING BY MIDDAY TUE, SO EXPECT VFR CONDITIONS THEN.
KPDX AND APPROACHES...A MIX OF VFR AND MVFR CONDITIONS IN POST
FRONTAL SHOWERS THROUGH TONIGHT, BUT MAY SEE MORE PERSISTENT MVFR
CIGS DEVELOP AFTER 10-12Z TUE AS THE AIR MASS SETTLES. DRIER
OFFSHORE FLOW WILL BRING VFR CONDITIONS BY MIDDAY TUE. /MH
MARINE
SOUTHERLY WINDS CONTINUE TO GUST TO AROUND 25 KT OVER
THE WATERS, BUT A LITTLE LESS NEARSHORE. EXPECT WINDS WILL
GRADUALLY SUBSIDE EARLY TUE, AND GENERALLY REMAIN 20 KT OR LESS
THROUGH TUE NIGHT. A SECOND SURFACE LOW WILL APPROACH THE COAST
ON WED, RESULTING IN ANOTHER OCCLUDED FRONTAL PASSAGE. THIS ONE
LOOKS TO BE A BIT STRONGER THAN TODAY'S FRONT, SO EXPECT ANOTHER
ROUND OF SOLID SMALL CRAFT ADVISORY WINDS, WITH AN OUTSIDE SHOT
AT SOME LOW-END GALES. WINDS SUBSIDE JUST A LITTLE ON THU, BUT
PROBABLY REMAIN GUSTY AS THE WEAKENING SURFACE LOW SLOWLY PUSHES
ONTO THE CENTRAL OR SOUTHERN OREGON COAST. ANOTHER FRONT MAY
ARRIVE OVER THE WEEKEND.
SEAS WILL BE HOVERING AROUND 10 FT THROUGH TONIGHT. IN ADDITION,
THEY WILL BE QUITE CHOPPY AS LONGER-PERIOD WESTERLY SWELL
INTERACTS WITH SHORT-PERIOD WIND WAVES AND FRESH SWELL BEING
GENERATED BY THE GUSTY SOUTHERLY WINDS. SEAS SHOULD DROP BACK
BELOW 10 FT BY EARLY TUE. THE WED/THU SYSTEM SHOULD PUSH SEAS
BACK INTO THE LOW TEENS FOR A PERIOD, BEFORE THEY DROP BACK BELOW
10 FT LATE IN THE WEEK. PYLE
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 AM PDT TUESDAY FOR
COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
60 NM.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT TUESDAY
FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
OUT 60 NM.
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THIS AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
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