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000
FXUS66 KPQR 231021
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
321 AM PDT THU MAY 23 2013

.SYNOPSIS...AN UNSEASONABLY COLD UPPER LEVEL CLOSED LOW REMAINS OVER
THE PAC NW TODAY AND WILL REMAIN NEARLY STATIONARY THROUGH FRI. THE
LOW WILL CONTINUE TO FEED WRAPAROUND MOISTURE ACROSS MUCH OF
SOUTHWEST
WASHINGTON AND NORTHWEST OREGON INTO FRIDAY. THE LOW WILL BEGIN TO
MOVE EAST FRIDAY AND THE PRECIPITATION WILL BREAK UP INTO A MORE
SHOWERY PATTERN. TEMPS WILL WARM A BIT OVER THE WEEKEND... BUT A
CHANCE FOR SHOWERS WILL REMAIN AS WEAK ENERGY MOVES THROUGH. A COUPLE
OF SYSTEMS ARE EXPECTED NEXT WEEK FOR MORE PRECIPITATION CHANCES.
&&

.SHORT TERM...THE UPPER LEVEL CLOSED LOW THAT HAS BEEN NEARLY
STATIONARY OVER THE PAC NW FOR THE PAST FEW DAYS IS CURRENTLY
CENTERED OVER NW WASHINGTON. WRAPAROUND MOISTURE COMBINED WITH A
PIECE OF EMBEDDED SHORTWAVE ENERGY HAS KEPT A BAND OF ENHANCED
PRECIPITATION GOING SINCE YESTERDAY AFTERNOON. MODEL CROSS-SECTIONS
SHOW A FAIRLY DEEP LAYER OF FRONTOGENESIS CONTRIBUTING TO THE
ENHANCED LIFT FROM THE SHORTWAVE. THE PRECIP BAND BECAME MORE FOCUSED
AND HEAVIER DURING THE EVENING AND HAS BEEN FOCUSED ALONG A LINE
ROUGHLY FROM TILLAMOOK FOR THE PDX/VUO METRO AREA AND INTO CLARK
COUNTY ALL THE WAY TO THE S WA CASCADES. RAINFALL TOTALS OVER THE
PAST 6 HRS HAVE TOTAL 3/4 TO 1.5 INCHES THROUGH THIS CORRIDOR.
COMBINING THIS WITH RAINFALL EARLIER IN THE DAY...A FEW SITES HAVE
RECORDED 24 HR RAINFALL TOTALS IN THE 2 TO 3 INCH RANGE.

A DRY SLOT OR BACK EDGE TO THE PRECIP IS VISIBLE ON THE LATEST RADAR
IMAGERY WORKING ITS WAY THROUGH COLUMBIA AND WASHINGTON COUNTY AND
INTO THE PORTLAND METRO AREA. EXPECT THIS SOUTHWARD PUSH TO CONTINUE
OVER THE NEXT FEW HRS...WITH THE HEAVIEST PRECIP FOCUSED THROUGH
YAMHILL AND CLACKAMAS COUNTIES THROUGH THE EARLY MORNING HRS. THE
LATEST FCST MODELS ARE INDICATING THAT THE BOUNDARY SHOULD LOSE SOME
OF ITS ORGANIZATION AND INTENSITY BETWEEN 12Z TO 18Z. BUT EXPECT
LIGHT PRECIPITATION TO CONTINUE ACROSS MOST OF THE REGION TODAY.

ANOTHER SHORTWAVE EMBEDDED IN THE LOW CURRENTLY NEARING VANCOUVER
ISLAND WILL ROTATE S AROUND THE LOW INTO THE REGION LATE THIS
AFTERNOON AND EVENING. THIS WILL BRING ANOTHER PERIOD OF ENHANCED
PRECIPITATION TO MOST OF THE FCST AREA THROUGH THE NIGHT. THE BACK
EDGE OF THE WAVE SHOULD PASS THROUGH TOWARDS DAYBREAK FRIDAY...WHICH
SHOULD BRING AN END TO THE HEAVIEST PRECIP.

SNOW LEVELS WILL HOVER AROUND 3500 FEET INTO FRIDAY...WITH THE SKI
RESORTS AND HIGHER TERRAIN OF THE CASCADES EXPECTED TO PICK UP
SIGNIFICANT ACCUMULATIONS. THE HIGHER MOUNTAIN PASSES WILL ALSO SEE
SOME SNOW. A COUPLE OF INCHES MAY STICK TO THE ROADS EARLY THIS
MORNING BEFORE ROAD TEMPS RISE ABOVE FREEZING TODAY...MELTING ANY
SNOW THAT ACCUMULATED OVERNIGHT. SNOW MAY STILL TRY TO STICK AT TIMES
LATER TODAY DURING ANY PERIODS OF HEAVIER SNOWFALL. THEN EXPECT SOME
ADDITIONAL LIGHT ACCUMULATIONS EARLY FRI MORNING AS TEMPS COOL AGAIN.
MOUNTAIN CLIMBING AND HIKING UP IN THE MOUNTAINS WILL BE HAZARDOUS
THROUGH FRI. A SPECIAL WEATHER STATEMENT HAS BEEN ISSUED TO HIGHLIGHT
THESE HAZARDS.

THE LOW BEGINS TO WEAKEN AND PUSH EAST OF THE REGION ON FRI. EXPECT
THE PRECIPITATION TO TURN MORE SHOWERY AND BROKEN UP. WE MIGHT SEE A
FEW BREAKS IN THE CLOUDS LATER FRIDAY WHICH COULD LEAD TO A MORE
DIURNAL SIGNAL TO THE SHOWERS FRIDAY AFTERNOON AND EVENING. TEMPS MAY
REACH 60 IN THE INTERIOR LOWLANDS.

MORE LIGHT SHOWERS ARE POSSIBLE ON SAT. MODEL UNCERTAINTIES INCREASE
OVER THE WEEKEND...BUT CONFIDENCE IS HIGH THAT THE PAC NW WILL REMAIN
UNDER THE INFLUENCE OF A TROUGHING PATTERN. HOWEVER...ANY SHOWERS
SHOULD REMAIN ON THE LIGHTER SIDE AND TEMPS WILL CONTINUE TO
MODERATE. MID 60S ARE A GOOD BET FOR MOST VALLEY LOCATIONS. SUNDAY
LOOKS QUITE SIMILAR TO SATURDAY...WITH LIGHT DIURNAL SHOWER CHANCES
EXPECTED TO CONTINUE. PYLE

.LONG TERM... THE MODELS SHOW MORE ORGANIZED SYSTEMS ARRIVING ALONG
THE WEST COAST EARLY NEXT WEEK WITH A CHANGE FROM INTERMITTENT
SHOWERS TO STEADY RAIN LIKELY DURING THE BEGINNING OF NEXT WEEK. SNOW
LEVELS RISE SLIGHTLY EARLY NEXT WEEK WITH TEMPERATURES STILL
REMAINING SLIGHTLY BELOW NORMAL. THERE IS STILL NO TENDENCY IN THE
LONG RANGE FORECAST FOR RIDGING TO RETURN TO THE NORTHWEST. KWELSON
&&

.AVIATION...UPPER LEVEL LOW OVER REGION CONTINUES TO GENERATE
AREAS OF RAIN. AREAS MOST LIKELY TO SEE IFR WILL BE THE COASTAL
AREAS WITH AREAS OF RAIN AND FOG. MVFR/VFR CIGS INLAND WITH AREAS
OF RAIN...LOCALLY HEAVY AT TIMES. MOUNTAINS WILL GENERALLY BE
OBSCURED THROUGH THE DAY. WITH A SLIGHTLY UNSTABLE AIR MASS WE
CANNOT RULE OUT A STRAY THUNDERSTORM TODAY...BUT THE BETTER CHANCE
WILL BE NORTH AND EAST OF OUR FORECAST AREA.

KPDX AND APPROACHES...HEAVIEST RAIN FROM OVERNIGHT APPEARS TO HAVE
SHIFTED SOUTHEAST OF KPDX FOR THE TIME BEING. EXPECT MVFR WITH
POSSIBLE BREAKS INTO VFR THIS MORNING WITH RAIN CONTINUING EAST
AND SOUTH OF THE METRO AREA. MIX OF MVFR/VFR TO CONTINUE INTO THIS
EVENING WITH OCCASIONAL RAIN AND LIGHT-MODERATE S-SE FLOW.  WEAGLE

&&

.MARINE...HAD TO HOLD ON THE SMALL CRAFT ADVISORY FOR SEAS A FEW
MORE HOURS AS BUOYS ARE RUNNING 10-11 FT THIS MORNING. SUSPECT BY
7 AM MOST OF THEM SHOULD BE BELOW 10 FT AND WILL BE ABLE TO DROP
THE SCA AT THAT POINT. WITH BROAD LOW PRESSURE STALLED OFF THE WA
COAST AND WEAK PRESSURE GRADIENTS...WINDS ARE GENERALLY LIGHT
ACROSS THE WATERS. A DISTURBANCE ROTATING AROUND THIS SYSTEM WILL
PROBABLY BRING SOME S WIND GUSTS TO 20 KT LATER THIS AFTERNOON AND
EVENING.

LOW PRESSURE WILL MOVE INLAND AND WEAKEN FRI/SAT...WITH LIGHT
WINDS AND DIMINISHING SEAS GOING INTO THE WEEKEND. THE NEXT SYSTEM
COULD INCREASE WINDS/SEAS LATE SUN OR MON...BUT THERE IS STILL
SOME UNCERTAINTY ON THE TRACK AND STRENGTH OF THIS SYSTEM.

MORNING EBBS WILL BE RATHER STRONG THE NEXT SEVERAL DAYS DUE TO
THE FULL MOON. THIS WILL LIKELY CREATE ROUGH BAR CONDITIONS DURING
THE STRONGER MORNING EBBS.  WEAGLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 AM PDT THIS
     MORNING FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE
     OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 AM
     EARLY THIS MORNING.

&&


$$

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.