000
FXUS66 KPQR 190947
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
246 AM PDT SUN MAY 19 2013

.SYNOPSIS...SHOWERS WILL DECREASE THIS MORNING AS A WEAK
WEATHER SYSTEM MOVES EAST OF THE AREA AND HIGH PRESSURE BUILDS. MORE
SUNBREAKS SUNDAY AFTERNOON SHOULD LEAD TO MORE SEASONABLE
TEMPERATURES. HIGH PRESSURE WILL HOLD OVER THE AREA MONDAY WHICH WILL
BE SUNNY AND WARM. HIGH CLOUDS WILL BEGIN TO INCREASE FROM THE
NORTHWEST MONDAY EVENING IN ADVANCE OF THE NEXT SYSTEM...WHICH WILL
BRING A DRAMATIC CHANGE BACK TO CHILLY AND UNSETTLED WEATHER TUESDAY
THROUGH FRIDAY.

&&

.SHORT TERM...RADAR IMAGERY SHOWS SHOWERS ACROSS NW OREGON EARLY THIS
MORNING AS AN UPPER LEVEL SHORTWAVE TROUGH MOVES OVER THE REGION.
THIS WAVE WILL MOVE EAST OF THE CASCADES AROUND SUNRISE AND HIGH
PRESSURE WILL BUILD OVER THE AREA. THE SHOWERS WILL BE MOSTLY
CONFINED TO THE COAST RANGE AND THE CASCADES AFTER SUNRISE...THEN
DISSIPATE IN THE AFTERNOON. CLEARING THIS AFTERNOON WILL RESULT IN
MORE SUNSHINE AND INLAND TEMPERATURES SHOULD WARM TO THE MID AND
UPPER 60S.

MONDAY WILL BE THE SUNNIEST AND WARMEST DAY OF THE WORK WEEK WITH
HIGH PRESSURE REMAINING OVER THE AREA. MODELED 850MB TEMPERATURES
SUGGEST DAYTIME HIGHS WILL WARM A FEW DEGREES ABOVE NORMAL MONDAY.

A SIGNIFICANT CHANGE IN WEATHER IS EXPECTED TUESDAY AS AN
UNSEASONABLY DEEP AND COLD UPPER LOW WILL MOVE OVER THE REGION. THIS
LOW WILL RETURN RAIN ON TUESDAY...WITH SNOW LEVELS LOWERING TO THE
CASCADE PASSES TUESDAY NIGHT. WEDNESDAY WILL BE THE COOLEST DAY OF
THE WEEK WITH THE UPPER LOW CONTINUING RAIN AND MOUNTAIN SNOW
SHOWERS. INSTABILITY  WILL RESULT IN ENHANCED SHOWERS IN THE
AFTERNOONS TUESDAY AND WEDNESDAY WITH SOME OF THE HEAVIER SHOWERS
CONTAINING SMALL HAIL. QPF AND CORRESPONDINGLY SNOW AMOUNTS ARE
DIFFICULT TO FORECAST FOR THESE TYPE OF LOANS.

CURRENTLY MODELS SUGGEST THAT SNOW AMOUNTS WILL REMAIN BELOW ADVISORY
CRITERIA...BUT CONVECTIVE SHOWERS TEND TO PRODUCE MORE THAN EXPECTED
PRECIPITATION. FORECASTING WHERE THE SHOWERS WILL BE THE MOST
CONSISTENT AND LIKELY HAVE THE HIGHER ACCUMULATIONS ADDS ANOTHER
CHALLENGE TO THE FORECAST. THE CURRENT FORECAST IS FOR NON-ADVISORY
SNOW...BUT WOULD NOT BE SURPRISED IF THIS CHANGES AS WE HAVE MORE
CONSISTENT MODEL DATA THE NEXT COUPLE OF DAYS.

.LONG TERM...WEDNESDAY EVENING THROUGH SATURDAY. CLOSED LOW PRESSURE
SYSTEM WILL LINGER OVER THE PAC NW THROUGH AT LEAST FRIDAY. EXPECT A
MORE DIURNAL TREND OF THE SHOWERS THURSDAY AND FRIDAY WITH LESS
SHOWERS AND POSSIBLE SUN BREAKS IN THE MORNINGS WITH SHOWER
ENHANCEMENT IN THE AFTERNOONS...ESPECIALLY FOR THE HIGHER TERRAIN.
TEMPERATURES WILL REMAIN BELOW THE SEASONAL NORMAL. MODELS ARE COMING
INTO BETTER AGREEMENT ON THE LOW MOVING EAST OF THE AREA FRIDAY
EVENING. DESPITE THE DEPARTURE OF THIS LOW...GENERAL LOW PRESSURE
WILL REMAIN OVER THE AREA AND CONTINUE SHOWERY AND
COOL CONDITIONS THROUGH MEMORIAL DAY WEEKEND.

&&

.AVIATION...RATHER MOIST AIR MASS ACROSS THE REGION THIS MORNING
WITH A MIX OF VFR AND MVFR CEILINGS. LITTLE CHANGE EXPECTED
THROUGH THE MORNING. WILL LIKELY SEE WIDESPREAD MVFR CEILINGS
BEFORE SUNRISE...THEN GRADUALLY BREAKUP OF CLOUDS AFTER 18Z AS
FLOW TURNS MORE N TO NWLY.

KPDX AND APPROACHES...MVFR CEILINGS WILL LIKELY FORM BY 12Z...AND
PERSIST THROUGH MUCH OF THE MORNING. LOCAL GUIDANCE SUGGESTS A
RETURN OF VFR CONDITIONS AROUND 19Z TO 20Z SUN. WILL MAINTAIN
THIS TREND IN THE 12Z TAFS.

&&

.MARINE...HIGH PRES OVER THE NE PAC WILL STRENGTHEN TONIGHT AND
SUN...WITH N TO NW WINDS. THESE WINDS WILL INCREASE AS PRES
GRADIENTS TIGHTEN SUN AND MON...WITH WIND GUSTS TO 25 KT S OF
NEWPORT IN AFTERNOON/EVENINGS. WILL MAINTAIN SMALL CRAFT ADVISORY
FOR CENTRAL OREGON COASTAL WATERS FOR SUCH WINDS FROM SUN
AFTERNOON THROUGH MON EVENING. WINDS WEAKER TO THE N...BUT COULD
GET A BIT GUSTY ON MON.

SEAS HOLDING AT 4 TO 6 FT THROUGH TUE...THOUGH MAY GET BIT CHOPPY
WITH BRISK NW WINDS AT TIMES...MAINLY S OF CASCADE HEAD.

QUESTIONABLE WEATHER FOR MIDDLE OF NEXT WEEK. MODELS INDICATE
LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING BY WED AND THU. THIS IS
DUE TO MODELS SPINNING UP ANOTHER RATHER TIGHT LOW PRES OFF THE
OREGON COAST ON TUE AND WED. NOT CONVINCED THIS WILL PAN OUT AS
MODELS SUGGEST...SO WILL TREND CLOSER TO 10 FT AND WAIT FOR FURTHER
CONSISTENCY IN MODEL DATA BEFORE BITING.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM NOON TODAY TO MIDNIGHT PDT
     MONDAY NIGHT FOR COASTAL WATERS FROM CASCADE HEAD TO
     FLORENCE OR OUT 10 NM-WATERS FROM CASCADE HEAD TO FLORENCE
     OR FROM 10 TO 60 NM.

&&

$$

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.