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000
FXUS66 KPQR 121010
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
310 AM PDT SUN MAY 12 2013

.SYNOPSIS...A FRONTAL SYSTEM NEAR THE COAST WILL WEAKEN AND DISSIPATE
AS MOVES ACROSS THE AREA TODAY. THE BULK OF THE RAINFALL WITH THIS
SYSTEM WILL REMAIN WELL TO THE NORTH...BUT WILL LIKELY SEE SOME LIGHT
PRECIP IN OUR NORTHERN ZONES TODAY. A REINFORCING UPPER LEVEL
SHORTWAVE WILL BRING MORE WIDESPREAD AND HEAVIER RAIN TO THE REGION
MONDAY. A FEW THUNDERSTORMS MAY DEVELOP ACROSS THE NORTHERN ZONES ON
MONDAY AS WELL. SEVERAL WEAK STORM SYSTEMS WILL SKIRT THE REGION NEXT
WEEK BRINGING CLOUDS...PERIODIC SHOWER ACTIVITY AND TEMPERATURES NEAR
SEASONAL NORMALS.

&&

.SHORT TERM...THE STRONG RIDGE OF HIGH PRESSURE THAT DOMINATED THE
WEATHER OVER THE PACNW FOR THE PAST SEVERAL DAYS HAS MOVED EASTWARD.
NEAR THE COAST...A FRONTAL SYSTEM WILL WEAKEN AND DISSIPATE AS IT
PUSHES INLAND TODAY. MOST OF THE ENERGY AND HEAVIER PRECIP WITH THIS
FRONT CONTINUES TO BE AIMED WELL TO THE NORTH TOWARD BC AND THE
OLYMPIC PENINSULA. THE HRRR MODEL SHOWS THE FRONT DISSIPATING AS IT
MOVES OVER THE COAST RANGE...WITH ANY SIGNIFICANT PRECIP MAINLY
AFFECTING THE NORTH COAST AND THE SOUTH WA AND NORTH OR CASCADES AND
FOOTHILLS.

A MORE POTENT SHORTWAVE WILL MOVE INTO THE REGION ON MONDAY. THIS
SYSTEM WILL DROP FURTHER SOUTH...WITH THE BASE OF THE TROUGH MOVING
THROUGH OREGON. THIS TRACK WOULD RESULT IN SIGNIFICANTLY MORE FORCING
OVER SW WASHINGTON AND NW OREGON WITH INCREASED WESTERLY OROGRAPHIC
FLOW.  SO...MONDAY APPEARS TO HOLD A MUCH BETTER SHOT FOR RECEIVING
SOME DECENT RAINFALL ACROSS OUR DISTRICT. MODELS ALSO SHOW QUITE
ABIT OF INSTABILITY FROM ABOUT SALEM NORTHWARD ON MONDAY
AFTERNOON...SO THERE IS ALSO A THREAT OF THUNDERSTORM ACTIVITY
MONDAY AFTERNOON INTO THE EARLY EVENING HOURS. TW

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
TUE THROUGH FRIDAY...AFTER THE SYSTEM ON MON PASSES THROUGH...THE PAC
NW WILL BE LEFT IN A RELATIVELY ZONAL PATTERN FOR THE REST OF THE
WEEK. A COUPLE OF WEAK TROUGHS ARE DEPICTED MOVING THROUGH THE UPPER
FLOW...SO WE WILL HAVE THE POTENTIAL FOR SOME SOME PERIODIC SHOWER
ACTIVITY. HOWEVER...NOTHING VERY WELL ORGANIZED IS EXPECTED.
OTHERWISE...EXPECT CLOUDS AND COOLER MORE SEASONAL TEMPS FOR NEXT
WEEK. PYLE

&&

.AVIATION...A COLD FRONT IS STALLED OFFSHORE THROUGH TONIGHT.
EXPECT SOME LIGHT RAIN AT TIMES ON THE COAST AND FAR NW OREGON AND
SW WASHINGTON. ON THE COAST...GENERALLY VFR CONDITIONS THIS
MORNING WITH OCCASIONAL MVFR CONDITIONS ESPECIALLY NORTH. CHANCES
FOR MORE WIDESPREAD MVFR INCREASE IN THE AFTERNOON AS THE WINDS
TURN MORE SOUTHWESTERLY. INLAND AREAS ARE EXPECTED TO REMAIN VFR
TODAY WITH MVFR CIGS POSSIBLE LATER TONIGHT.

KPDX AND APPROACHES...VFR EXPECTED THROUGH 06Z MON. AFTER THAT
MODELS ARE INDICATING INCREASING CHANCES FOR MVFR CIGS AROUND
2500-3000 FEET. BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE MVFR
CONDITIONS IN THE 12Z TAFS.

&&

.MARINE...FRONT REMAINS OFFSHORE WITH SLOW EASTWARD PROGRESS AS
SEVERAL WAVES RIDE ALONG THE FRONT. MAIN CHANGES FOR TODAY IS TO
ADJUST TIMING OF THE MARGINAL SMALL CRAFT ADVISORY FOR THE
NORTHERN OUTER WATERS TO 5 AM TO 11 AM TODAY. A STRONGER WAVE WILL
MOVE ALONG THE FRONTAL BOUNDARY ON MON AND WILL PROBABLY BRING A
MORE SOLID SMALL CRAFT ADVISORY EVENT.

SEAS SHOULD REMAIN 4 TO 6 FT RANGE TODAY THEN INCREASE FURTHER
WITH THE SYSTEM ON MON...POTENTIALLY REACHING NEAR 10 FT LATE MON.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 5 AM TO 11 AM PDT THIS
     MORNING FOR WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD
     OR FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 5 AM
     TO 9 AM PDT 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.