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000
FXUS66 KPQR 212137
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
237 PM PDT TUE MAY 21 2013

.SYNOPSIS...A COLD UPPER LOW WILL ANCHOR ITSELF OVER THE PACIFIC NW
FOR THE REMAINDER OF THE WEEK...KEEPING A COOL SHOWERY WEATHER
PATTERN IN PLACE FOR THE NEXT FEW DAYS. THE LOW WILL WEAKEN OVER THE
WEEKEND...REDUCING THE CHANCES FOR SHOWERS...AND ALLOWING TEMPS TO
WARM BACK CLOSER TO NORMAL.

&&

.SHORT TERM...EARLY TUE AFTERNOON SATELLITE SHOWED THE MAIN TROUGH
AXIS PUSHING ONTO THE COAST. WATER VAPOR PICTURES SHOWED THE UPPER
LOW WITH TWO MAIN VORTICTY MAXIMA...ONE ROTATING INLAND OVER SW
OREGON AND THE SECOND DIGGING DOWN THE BACKSIDE OF THE LOW NEAR 46N
131W. MODELS INDICATE THE UPPER LOW IS TO REMAIN OVER THE PACIFIC NW
FOR THE NEXT FEW DAYS...WITH SHORTWAVES ROTATING AROUND THE LOW
CAUSING A DUMBELL EFFECT. INITIALLY THIS SHOULD FAVOR WIDESPREAD
SHOWERS TONIGHT THROUGH THU AS THE LARGE AREAS OF SHOWERS SEEN
OFFSHORE MOVE INLAND WITH WITH AN ONSHORE FLOW. PROBABLY DUE TO A
COOL BOUNDARY LAYER...BUFR SOUNDINGS TENDING TO NOT LOOK UNSTABLE
ENOUGH TO CARRY ANY MENTION OF THUNDER...EVEN AS THE COLDEST AIR
ALOFT MOVES ACROSS TONIGHT. WILL HOWEVER CONTINUE TO MENTION SMALL
HAIL WITH THE SHOWERS DUE TO LOW FREEZING LEVELS.

WILL TREND TOWARDS LOWER POPS LATE WED NIGHT AND THU AS MODELS
SUGGEST THE POSSIBILITY OF DRIER AIR WORKING IN UNDER THE LOW AS THE
MAIN LOW CENTER ROTATES UP THROUGH NORTHERN WA. WHILE THE DETAILS
ARE QUESTIONABLE AT THIS POINT...WILL SHOW A LITTLE BETTER CHANCE
FOR SHOWERS AGAIN FRI AS THE UPPER LOW SWINGS BACK AROUND THROUGH
OREGON. TEMPS ARE LIKELY TO BE AT THEIR COOLEST WED WITH A DEEP
CLOUD LAYER AND ONSHORE FLOW.

.LONG TERM...FRIDAY EVENING THROUGH MONDAY...SEVERAL SHORTWAVE
SYSTEMS ROTATE THROUGH A BROAD UPPER LEVEL LOW OVER THE NORTHEAST
PACIFIC AND WEST COAST. THE UPPER LOW LINGERS ACROSS THE REGION
THROUGH THIS WEEK AND INTO THE WEEKEND...KEEPING PERIODS OF SHOWERS
MIXED WITH SPORADIC SUN BREAKS IN THE FORECAST.
SNOW LEVELS RISE ABOVE CASCADE PASS LEVEL AND TEMPERATURES WARM UP
CLOSER TO NORMAL TOWARD THE BEGINNING OF NEXT WEEK...THOUGH WET AND
UNSETTLED WEATHER APPEARS TO CONTINUE THROUGH EARLY NEXT WEEK.
KWELSON

&&

.AVIATION...EXPECT A MIX OF MVFR AND VFR CONDITIONS ACROSS THE
WILLAMETTE VALLEY LATE THIS AFTERNOON AS A BAND OF STEADY RAIN
SHIFTS ACROSS THE REGION. CONDITIONS SHOULD TURN MORE SHOWERY THIS
EVENING AND BECOME GENERALLY VFR WITH ONLY AN OCCASIONAL BRIEF DIP
INTO THE MVFR CATEGORY. LIFT AHEAD OF THE NEXT LOW PRESSURE DROPPING
DOWN THE COAST SHOULD PRODUCE WIDESPREAD MVFR CIGS ACROSS THE REGION
LATE TONIGHT INTO WEDNESDAY MORNING.

KPDX AND APPROACHES...CONDITIONS SHOULD GENERALLY BE VFR THROUGH
THIS EVENING. HOWEVER...WE MAY SEE SOME TEMPORARY MVFR CONDITIONS
LATE THIS AFTERNOON AS A STEADIER BAND OF LIGHT RAIN MOVES INTO
THE AREA. CONDITIONS LOOK TO TREND MORE TOWARDS MVFR LATE TONIGHT
INTO WEDNESDAY MORNING AS AN AREA OF LIGHT RAIN SPREADS INTO THE
REGION FROM THE WEST. /NEUMAN

&&

.MARINE...EXPECT PERIODS OF 15 TO 20 KT WINDS WITH GUSTS UP TO 30
KT...MAINLY TIED TO SHOWERS THROUGH WEDNESDAY. THERE MAY SOME
DISTINCT LULLS IN THE WINDS...PARTICULARLY BETWEEN SHOWERS AND NORTH
OF THE COLUMBIA RIVER...BUT TIMING THESE DETAILS REMAINS UNCERTAIN
ENOUGH THAT WE WILL NOT GET CUTE WITH THE HEADLINES.

THE TREND WILL BE TOWARD MORE BENIGN WEATHER LATE THIS WEEK INTO
NEXT WEEKEND AS THE UPPER LOW WEAKENS AND HIGHER SURFACE PRESSURE
BUILDS INTO THE WATERS.

SEAS SHOULD GENERALLY HOVER IN THE 10 TO 12 FT RANGE FOR THE NEXT
24 HOURS BEFORE GRADUALLY SUBSIDING THURSDAY THROUGH THE WEEKEND.
/NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 PM PDT WEDNESDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 PM PDT WED
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL
     5 PM PDT WEDNESDAY.
&&


$$

MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.