000
FXUS66 KPQR 151550
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
850 AM PDT WED MAY 15 2013

.SYNOPSIS...A WEAK LOW PRESSURE SYSTEM WILL MOVE INTO SOUTHWEST
WASHINGTON AND NORTHWEST OREGON TODAY...SPREADING LIGHT RAIN INTO A
GOOD PORTION OF THE FORECAST AREA...ESPECIALLY ACROSS THE OREGON
COAST RANGE AND SOUTHWEST WASHINGTON. THE LOW PRESSURE WILL PERSIST
OVER THE FORECAST AREA THURSDAY INTO FRIDAY OCCASIONALLY SPREADING IN
SOME MOISTURE AT TIMES FOR A CHANCE FOR SHOWERS. ANOTHER WEATHER
SYSTEM WILL BRING SHOWERS TO THE PACIFIC NORTHWEST SATURDAY THAT WILL
DECREASE ON SUNDAY. YET ANOTHER POSSIBLY COOLER SYSTEM IS EXPECTED
AROUND TUESDAY.
&&

.SHORT TERM...WATER VAPOR PICTURES THIS MORNING SHOWED A COUPLE OF
SHORTWAVES APPROACHING THE OREGON COAST. FIRST VORT MAX WAS AROUND
42N 127W APPROACHING THE S OREOGN COAST...THE SECOND NEAR 43N 131W
HEADED TOWARD THE N OREOGN S WA COAST. VISIBLE PICTURES INDICATED
DEEPER MOISTURE WAS APPROACHING THE OREGON COAST...SUGGESTING HIGHER
POPS MIGHT BE IN ORDER TODAY ESP FOR THE S PART OF THE FORECAST
AREA. WITH PLENTY OF CLOUDS AND SOME RAIN...TEMPS ARE LIKELY TO BE A
BIT COOLER THAN YESTERDAY.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...
THERE IS A TRAILING MOISTURE FEED ALONG THE FRONTAL BOUNDARY THAT
EXTENDS WELL OFFSHORE ALONG 40N LATITUDE. AS THE UPPER TROUGH LINGERS
NEAR OUR AREA TONIGHT AND THURSDAY...THE MODELS ARE INDICATING THAT
THIS MOISTURE WILL BE AIMED TOWARD NORTHERN CALIFORNIA...BUT SOME MAY
SPREAD BACK NORTH INTO NORTHWEST OREGON TO FEED SOME SHOWERS OVER OUR
AREA LATER TONIGHT AND THURSDAY. THE GREATEST QPF FROM THIS WOULD BE
DOWN NEAR LANE COUNTY. WE MAY ALSO SEE A DIURNAL INCREASE IN THE
SHOWERS THURSDAY AFTERNOON AND EARLY EVENING AS SHOWERS BUILD OVER
THE HIGHER TERRAIN AND THE SPREAD OVER THE VALLEYS.

THE UPPER TROUGH WILL BEGIN TO MOVE EAST ON FRIDAY...BUT SOME
SHOWERS WILL LIKELY LINGER OVER OUR AREA. DAYTIME HEATING MAY AGAIN
CONTRIBUTE TO AN AFTERNOON AND EVENING INCREASE IN THE SHOWERS.

THE AIR MASS THE NEXT FEW DAYS WILL CONTINUE TO BE COOL...KEEPING
DAYTIME HIGHS NEAR NORMAL. SOME OF THE LATE DAY SHOWERS MIGHT HAVE
SOME SMALL HAIL OR BRIEF HEAVY SHOWERS THURSDAY AND FRIDAY AS WELL.
WHILE THIS SYSTEM IS NOT REAL COLD ALOFT...MODEL SOUNDINGS SHOW SOME
STEEPER LAPSE RATES DEVELOPING AND WE MIGHT GET CLOSE TO DEVELOPING
A CLAP OF THUNDER OR TWO THURSDAY AND FRIDAY. TOLLESON

.LONG TERM...FRIDAY EVENING THROUGH TUESDAY...THE MODELS SHOW ANOTHER
DECENT WEATHER SYSTEM DROPPING IN FROM THE NORTHWEST OVER SOUTHWEST
WASHINGTON AND NORTHWEST OREGON ON SATURDAY...LINGERING INTO SUNDAY.
THIS WILL BRING SHOWERS ACROSS THE AREA...WITH SOME POTENTIAL TO DROP
SNOW LEVELS A BIT IN THE CASCADES. WE MAY GET A DRY DAY MONDAY
BEFORE ANOTHER SYSTEM FOR MONDAY NIGHT AND TUESDAY. BOTH RECENT RUNS
OF THE GFS AND ECMWF SUGGEST SNOW LEVELS TUESDAY COULD LOWER TO
BELOW PASS ELEVATIONS IN THE CASCADES. TOLLESON
&&

.AVIATION...LIGHT RAIN IS BEGINNING TO PUSH INTO MUCH OF THE
WILLAMETTE VALLEY. CIGS WILL GENERALLY BE VFR THIS MORNING WITH MVFR
CIGS PROBABLE ALONG THE COAST THIS AFTERNOON...SPREADING TO INTERIOR
TAF SITES TONIGHT.

KPDX AND APPROACHES...EXPECT MAINLY VFR CONDITIONS THROUGH THIS
AFTERNOON. MVFR CIGS LOOK INCREASINGLY LIKELY OVERNIGHT...BUT
TIMING IN THEIR FORMATION REMAINS UNCERTAIN...MAYBE TOWARDS 09Z OR
SO. /NEUMAN

&&

.MARINE...A FRONT OFF THE OREGON COAST IS EXPECTED TO MOVE ACROSS
THE WATERS TODAY...LIKELY REACHING THE COAST THIS AFTERNOON. WIND
GUSTS AROUND 20 KT APPEAR LIKELY JUST AHEAD OF THE FRONT THIS
AFTERNOON ACROSS THE NORTHERN WATERS. WIDESPREAD WIND GUSTS OVER
20 KT APPEAR UNLIKELY SO WILL HOLD OFF ON A SMALL CRAFT ADVISORY
FOR NOW. OTHERWISE...A BROAD TROUGH OF LOW PRESSURE WILL HANG OVER
THE REGION KEEPING WINDS AND SEAS LOW THROUGH THE END OF THE WORK
WEEK. THE NEXT FRONT THAT MAY CAUSE WINDS TO JUMP ABOVE 20 KT
SHOULD ARRIVE AROUND SATURDAY MORNING. /NEUMAN

&&

.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.