000
FXUS66 KPQR 192222
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
321 PM PDT SUN MAY 19 2013

.SYNOPSIS...HIGH PRESSURE WILL BUILD INTO OREGON THIS EVENING...
CAUSING SKIES TO CLEAR FOR MUCH OF THE FORECAST AREA. 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...TONIGHT THROUGH WEDNESDAY...SKIES HAVE BEEN SLOW TO
CLEAR FOR MOST OF OUR FORECAST AREA TODAY...AS FLOW HAS REMAINED
RATHER LIGHT AND LOW LEVEL MOISTURE REMAINS PERSISTENT. HIGH PRESSURE
IS STRENGTHENING ACROSS THE REGION SO EXPECT SUBSIDENCE TO EVENTUALLY
TAKE OVER FOR CLEARING SKIES THIS EVENING.

EXPECT PLENTY OF SUNSHINE MONDAY AS HIGH PRESSURE BECOMES MORE
DOMINANT. THE AIR MASS WILL ALSO BE WARMING UP A BIT...WITH 850 MB
TEMPS UP FROM +4 DEG C TODAY TO AROUND +10 DEG C MON AFTERNOON PER
THE 12Z ECMWF. WITH NEAR FULL SUNSHINE THIS SHOULD BE GOOD FOR TEMPS
WELL INTO THE 70S FOR THE INLAND VALLEYS. FLOW WILL STILL BE ONSHORE
SO THE COAST WILL REMAIN COOL WITH HIGHS NOT STRAYING TOO FAR FROM 60
DEGREES.

HIGH CLOUDS WILL BE ON THE INCREASE LATER MONDAY INTO MONDAY NIGHT AS
A SIGNIFICANT COLD FRONT APPROACHES FROM ALASKA. RAIN WILL BECOME
LIKELY FOR MOST OF THE FORECAST AREA BY MIDDAY TUESDAY...WITH A SHARP
DROP IN TEMPERATURES AND SNOW LEVEL ASSOCIATED WITH THE COLD FRONT.
INTERIOR VALLEYS WILL SEE HIGHS 15 TO 25 DEGREES COLDER TUE/WED THAN
THEY DID MONDAY. WITH THE COLDER AIR MASS...SNOW LEVEL WILL DROP
BELOW THE CASCADE PASSES. ACCUMULATING SNOW WILL BE POSSIBLE DOWN AS
LOW AS 2500 TO 3000 FT BY TUE NIGHT AND WED...ESPECIALLY DURING THE
NIGHTTIME HOURS. HIGH TEMPS TUE/WED MAY BE COLD ENOUGH TO SET NEW
RECORD LOW MAXES...FOR PDX THIS WOULD BE 52 ON TUE AND 55 WED. OUR
FORECAST OF 54 DEGREES AT PDX WED WOULD ACHIEVE A RECORD.

WITH SUCH A COLD AND UNSETTLED AIR MASS DURING THE MIDWEEK PERIOD...
ALONG WITH LOW FREEZING LEVELS...IT IS LIKELY HEAVIER SHOWERS WILL
COME WITH SMALL HAIL. THERE IS ALSO THE POSSIBILITY FOR THUNDER
DEPENDING ON THE EXACT TRACK OF THE COLD POOL ALOFT. SOME MODEST
DIRECTIONAL SHEAR WEDNESDAY MAY AID THUNDERSTORM DEVELOPMENT...BUT
AGAIN THIS DEPENDS ON THE TIMING OF INDIVIDUAL SHORTWAVES ROTATING
AROUND THE BROADER UPPER LEVEL LOW. WILL HOLD OFF ON ADDING THUNDER
MENTION FOR NOW SINCE THERE IS STILL A LOT OF UNCERTAINTY AS TO HOW
THESE EXACTLY THESE ELEMENTS WILL COME TOGETHER.  WEAGLE


.LONG TERM...WEDNESDAY EVENING THROUGH SUNDAY...A LINGERING CLOSED
LOW PRESSURE SYSTEM WILL KEEP THE AREA SHOWERY AND COOL THROUGH THE
WEEK. WITH THE COLD NATURE OF THE LOW...EXPECT SNOW DOWN TO PASS
LEVEL IN THE CASCADES WEDNESDAY NIGHT....WITH SNOW LEVELS RISING
ABOVE THE PASSES THURSDAY AFTERNOON. MODELS HAVE COME INTO BETTER
AGREEMENT FOR THE LONG TERM AND TAKE THE LOW NORTHEAST ON
SATURDAY...WITH A FEW SHOWERS POSSIBLE AS MOISTURE WRAPS AROUND THE
WEST SIDE OF THE LOW. AT THIS TIME SUNDAY LOOKS DRY BUT
CLOUDY...WITH MODEL DISCREPANCIES EMERGING IN REGARD TO THE NEXT
SYSTEM THAT MAY IMPACT THE AREA LATE SUNDAY. BURGESS

&&

.AVIATION...HIGH PRESSURE WILL CONTINUE TO STRENGTHEN OVERNIGHT
INTO MONDAY ALLOWING VFR CONDITIONS TO PREVAIL FOR THE NEXT 24
HRS. CEILINGS AROUND 5K FT WILL CONTINUE THROUGH THIS AFTERNOON
AND EVENING... GRADUALLY DISSIPATING OVERNIGHT. SOME LOW
STRATUS/PATCHY FOG MAY ATTEMPT TO FILL BACK IN AT SITES THAT SAW
SOME LOW CLOUDS THIS MORNING...SUCH AS KSLE IN PARTICULAR. /27

KPDX AND APPROACHES...VFR CONDITIONS THROUGH THE NEXT 24 HRS. BKN
CLOUD DECK AROUND 5K FT WILL GRADUALLY LIFT LATER TONIGHT.

&&

.MARINE...HIGH PRES OVER THE NE PAC WILL STRENGTHEN OVERNIGHT...WITH
N TO NW WINDS. THE SMALL CRAFT ADVISORY FOR WINDS OVER THE CENTRAL
OREGON COASTAL WATERS IS STAYING STRONG AS PRESSURE GRADIENTS
TIGHTEN THROUGH MONDAY... ALLOWING GUSTS TO 25 KT FROM NEWPORT
SOUTH. A FEW GUSTS 20-25 KT ARE POSSIBLE OVER THE NORTHERN
WATERS...BUT OVERALL WINDS SHOULD STAY BELOW CRITERIA. 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.

MODELS ARE HINTING AT A LARGE FETCH OF 10 TO 15 FT SWELL ARRIVING
BY MID WEEK. SINCE SOLUTIONS HAVE BEEN RATHER CONSISTENT IN
INDICATING SOME HIGH SWELL BY WED AND THU...WENT AHEAD AND UPPED
SEAS CLOSER TO THE 10 TO 11 FT RANGE. WOULD LIKE A FEW MORE MODEL
RUNS TO DECIDE ON FORECASTING ANY HIGHER SWELL THOUGH.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 PM PDT MONDAY 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.