000
FXUS66 KPQR 170946
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
245 AM PDT FRI MAY 17 2013

.SYNOPSIS...A FEW SHOWERS WILL CONTINUE TODAY ESPECIALLY IN THE
CASCADES AS A WEAK SYSTEM SLIDES TO THE EAST. TRANSITORY HIGH
PRESSURE MAY BRING A BRIEF BREAK IN THE SHOWERS TONIGHT BEFORE THE
NEXT SYSTEM BRINGS ANOTHER DECENT CHANCE FOR RAIN SATURDAY AND
LINGERING SHOWERS SUNDAY. DRIER WEATHER IS EXPECTED SUN NIGHT/MON...
BUT IT IS LOOKING MORE LIKELY THAT A COOL AND UNSETTLED PATTERN WILL
SET UP OVER THE PACIFIC NORTHWEST FOR THE MIDDLE OF NEXT WEEK.

&&

.SHORT TERM...SHOWERS WILL CONTINUE TODAY ESPECIALLY ACROSS THE
CASCADES AS A WEAK SYSTEM SLIDES TO THE EAST. MODEL SOUNDINGS SHOW
SHALLOW INSTABILITY UP TO 600-700 MB. THIS SHOULD GREATLY LIMIT
SHOWER POTENTIAL TODAY DESPITE A LITTLE MORE SUNSHINE...BUT THERE
WILL STILL BE ENOUGH INSTABILITY FOR SCATTERED SHOWERS THROUGHOUT
THE DAY. THESE WILL DISSIPATE THIS EVENING AS HIGH PRESSURE BRIEFLY
BUILDS OVERHEAD. HOWEVER...THE NEXT SYSTEM NOW NEAR 150W WILL LIKELY
SPREAD RAIN BACK ACROSS THE DISTRICT SATURDAY. QPF SHOULD BE MODEST
WITH AROUND 0.25 INCH IN THE VALLEYS AND UP TO 1 INCH IN THE HIGHER
TERRAIN. RAIN WILL TAPER TO SHOWERS SATURDAY NIGHT WITH A FEW
LINGERING INTO SUNDAY...MAINLY OVER THE HIGHER TERRAIN.

TEMPERATURES WILL HOVER A LITTLE BELOW NORMAL THROUGH THE WEEKEND.
SNOW LEVELS SHOULD REMAIN ABOVE THE PASSES THROUGHOUT THE
WEEKEND...BUT MAY GET AS LOW AS 4500-5000 FT AT TIMES.

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...SUNDAY NIGHT
THROUGH THURSDAY...AFTER A BRIEF BREAK OF POTENTIALLY SUNNY AND
SEASONABLE WEATHER MONDAY...IT APPEARS AN EXTENDED COOL AND
UNSETTLED PERIOD IS BECOMING INCREASINGLY LIKELY FOR MIDWEEK. MODELS
ARE SHOWING RELATIVELY GOOD AGREEMENT THAT A COLD AND CLOSED UPPER
LOW WILL DIG DOWN FROM ALASKA...SETTLING SOMEWHERE NEAR THE PAC NW
TUE AND LINGERING THROUGH THURSDAY. COLD AIR ALOFT WILL KEEP THE AIR
MASS UNSTABLE...WITH COOL SHOWERY WEATHER AND POSSIBLY EVEN A
THUNDERSTORM OR TWO DEPENDING ON HOW THINGS EVOLVE.

FAIRLY HIGH DEGREE OF CONFIDENCE OF BELOW NORMAL TEMPS DURING THIS
PERIOD ALONG WITH HIT AND MISS SHOWERS. SNOW LEVELS MAY VERY WELL GET
BELOW THE PASSES...BUT WE WILL PLAY IT CONSERVATIVE FOR NOW WITH SNOW
LEVELS BOTTOMING OUT AROUND 4000-4500 FT MIDWEEK. IF MODELS CONTINUE
TO BRING THE CENTER OF THE COLD POOL OVER THE PAC NW...THESE SNOW
LEVELS WILL NEED TO COME DOWN A BIT AND POSSIBLY AS LOW AS 2000-3000
FEET.  WEAGLE

&&

.AVIATION...CONSIDERABLE CLOUDS WILL CONTINUE OVER SOUTHWEST
WASHINGTON AND NORTHWEST OREGON TODAY AS A WEAK LOW CONTINUES OFF
THE COAST AND SLOWLY FILLS. THE SOUTHEAST FLOW AROUND THIS LOW WAS
SPREADING SHOWERS FROM CENTRAL OREGON ACROSS THE NORTH OREGON
CASCADES INTO SOUTHWEST WASHINGTON...AND WILL CONTINUE UNTIL AFTER
SUNRISE UNTIL THE MAIN UPPER TROUGH MOVES FARTHER EAST. THE FLOW
WILL TURN MORE SOUTHWESTERLY AND WESTERLY THIS AFTERNOON WITH A
FEW SHOWERS SPREADING OFF THE HIGHER TERRAIN OVER THE VALLEYS.
LOOK FOR VFR CIGS TODAY WITH SOME MVFR CIGS MIXED IN THIS MORNING.
EXPECT MOSTLY VFR CIGS TONIGHT WITH DECREASING SHOWERS BUT CANNOT
RULE OUT SOME PATCHES OF MVFR CIGS BY SUNRISE SATURDAY.

KPDX AND APPROACHES...VFR CIGS TODAY WITH POSSIBLE MVFR CIGS THIS
MORNING. SOME SHOWERS SPREADING IN FROM THE SOUTHEAST MAY AFFECT
THE AIRPORT AT TIMES THIS MORNING...AND ESPECIALLY THE EASTERN
APPROACHES. THE FLOW WILL TURN MORE WESTERLY THIS AFTERNOON AND
COULD STILL SEE A SHOWER OR TWO DRIFT OFF THE COAST RANGE AND
AFFECT THE AIRPORT THIS AFTERNOON AND EVENING. THERE IS A CHANCE
OF MVFR CIGS BY SUNRISE SATURDAY. PT
&&

.MARINE...WINDS WILL REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS
TODAY AND MOST OF TONIGHT AS ONE SYSTEM WEAKENS AND MOVES EAST AND
BEFORE THE NEXT SYSTEM ARRIVES. PREFRONTAL SOUTHERLY SMALL CRAFT
ADVISORY WINDS ARE POSSIBLE BY EARLY SATURDAY AND THROUGH MOST OF
SATURDAY. NORTHWEST WINDS WILL THEN PREDOMINATE THE REMAINDER OF
THE WEEKEND AND MUCH OF NEXT WEEK...AND MAY REQUIRE A SMALL CRAFT
ADVISORY AGAIN ESPECIALLY NEXT WEEK.

SEAS ARE FORECAST TO REMAIN AROUND 5 OR 6 FT FOR SEVERAL DAYS...
POSSIBLY 7 FT OR SO WITH THE FRONT SATURDAY. WE MAY SEE SEAS
REACH 10 FT NEXT WEEK DUE TO THE BRISK NORTHWEST WINDS. PT
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&

$$

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.