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000
FXUS66 KPQR 191615
AFDPQR

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

.SYNOPSIS...CLOUDS AND SCATTERED SHOWERS WILL GRADUALLY DECREASE
TODAY AS HIGH PRESSURE BUILDS INTO THE PACIFIC NORTHWEST. MORE
SUNBREAKS THIS AFTERNOON SHOULD LEAD TO MORE SEASONABLE TEMPERATURES
ESPECIALLY FOR THE LOWLANDS. THE HIGH PRESSURE WILL BE STRONGEST OVER
THE AREA MONDAY...LEADING TO A SUNNY AND WARM DAY. HIGH CLOUDS FROM
OUR NEXT SYSTEM WILL BEGIN TO INCREASE LATER MONDAY AND MONDAY NIGHT
EVENTUALLY LEADING TO SOME RAIN BY TUESDAY. THIS SYSTEM WILL COME
WITH A SHARP DROP IN TEMPERATURES AND SNOW LEVELS...WITH COOL AND
UNSETTLED WEATHER THEN LIKELY TO CONTINUE FOR THE REST OF THE WEEK.

&&

.SHORT TERM...TODAY THROUGH WEDNESDAY...OBSERVATIONS AND RADAR
IMAGERY STILL INDICATE A FEW SHOWERS DOTTING THE FORECAST AREA...
MAINLY OVER THE CASCADES. VISIBLE SATELLITE IS BEGINNING TO SHOW SOME
CLEARING OVER THE TUALATIN VALLEY AND WESTERN PORTIONS OF THE
WILLAMETTE AS WELL. THIS LIKELY DUE TO INCREASED ONSHORE FLOW AND
DOWNSLOPING ON THE EAST SIDE OF THE COAST RANGE. THIS OVERALL PATTERN
WILL CONTINUE THROUGH THE DAY...WITH HIGH PRESSURE BUILDING IN CLOUD
COVER WILL GRADUALLY DECREASE WITH THE WEST HALF OF THE WILLAMETTE
VALLEY AND THE HOOD RIVER VALLEY BEING THE SUNNIEST. WITH THE
INCREASE IN SUNSHINE TEMPS SHOULD COME CLOSER TO SEASONAL NORMS...
WITH MID TO UPPER 60S.

MAIN CHANGE TO THE MORNING FCST WAS TO HANG ON TO THE CLOUD COVER
OVER THE HIGHER TERRAIN A LITTLE LONGER...BUT OTHERWISE THE FORECAST
LOOKS TO BE IN GOOD SHAPE. REMAINDER OF SHORT/LONG TERM DISCUSSION IS
FROM THE PREVIOUS SHIFT AND STILL VALID... WEAGLE

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...MOIST AIR MASS MAINTAINS MVFR AND VFR CEILINGS THIS
MORNING. EXPECT CLOUDS TO GRADUALLY BREAK UP CLOSER TO 19Z...WITH
PREDOMINANTLY VFR CONDITIONS CONTINUING THROUGH THIS EVENING. HIGH
PRESSURE STRENGTHENS OVERNIGHT...WITH SOLID VFR EXPECTED THROUGH
MON.

KPDX AND APPROACHES...MVFR CEILINGS PERSISTS THROUGH 19Z/20Z THIS
MORNING...THEN EXPECT VFR CONDITIONS THROUGH TONIGHT AND MONDAY.
BKN CLOUD DECK AROUND 5K WILL LIKELY LINGER THROUGH THIS EVENING.
/27

&&

.MARINE...HIGH PRES OVER THE NE PAC WILL CONTINUE TO STRENGTHEN
TODAY AND TONIGHT...WITH N TO NW WINDS. THESE WINDS WILL INCREASE
AS PRES GRADIENTS TIGHTEN THROUGH 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
THIS 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
     OUT 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.