000
FXUS66 KPQR 121559
AFDPQR

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

.SYNOPSIS...A FRONTAL SYSTEM NEAR THE COAST WILL WEAKEN AND DISSIPATE
AS IT MOVES ACROSS THE AREA TODAY. THE BULK OF THE RAINFALL WITH THIS
SYSTEM WILL REMAIN WELL TO THE NORTH...BUT WILL LIKELY CONTINUE TO
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. GIVEN THE RECENT WARM AIRMASS THERE MAY BE ENOUGH ENERGY
TO ENHANCE SHOWER ACTIVITY THIS AFTERNOON ACROSS THE INTERIOR AS WHAT
REMAINS OF THE FRONT MOVES THROUGH.

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
A BIT 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.

.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 SLOWLY PUSHING ONSHORE THIS MORNING.
EXPECT LIGHT SHOWERS AND PERIODS OF MVFR CIGS AS THE FRONT SLOWLY
MOVES THROUGH...ESPECIALLY THROUGH ABOUT 20Z. CHANCES FOR MORE
WIDESPREAD MVFR INCREASE THIS EVENING AS THE WINDS TURN MORE
SOUTHWESTERLY. A STRONGER FRONT WILL MOVE IN OVERNIGHT INTO
MON...BRINGING HEAVIER RAIN AND LOWERED CIGS.

KPDX AND APPROACHES...EXPECT PERIODIC LIGHT RAIN AND MVFR CIGS
TODAY AS A WEAK FRONT SLOWLY PUSHES THROUGH. A STRONGER FRONT WILL
BRING HEAVIER RAIN AND PREDOMINANTLY MVFR CIGS BETWEEN 12Z AND 18Z
TOMORROW MORNING. PYLE

&&

.MARINE...A WEAK COLD FRONT IS PUSHING INLAND THIS MORNING. WINDS
ARE RUNNING LOWER THAN THE MODELS ARE SUGGESTING...SO DECIDED TO
END THE SMALL CRAFT ADVISORY FOR WINDS THIS MORNING. A STRONGER
WAVE WILL MOVE ALONG THE FRONTAL BOUNDARY ON TOMORROW MORNING AND
MON...WHICH SHOULD 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...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.