Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 230940
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND
240 AM PDT SAT MAY 23 2015

.SYNOPSIS...AN UPPER LOW WILL REMAIN OVER THE WESTERN U.S. THROUGH
EARLY NEXT WEEK WITH A NARROW RIDGE OF HIGH PRES OFFSHORE. A LOW
LEVEL ONSHORE FLOW WILL KEEP MARINE AIR OVER THE FORECAST AREA
THROUGH EARLY NEXT WEEK. A GRADUAL WARMING TREND IS EXPECTED MID TO
LATE NEXT WEEK.
&&

.SHORT TERM...WATER VAPOR SHOWED MAIN UPPER TROUGH AXIS WAS WELL
INLAND OVER ID AND EASTERN NV. RADAR SHOWED SOME SHOWERS CONTINUED
TO SPREAD W AS FAR AS THE COAST EARLY THIS MORNING...AIDED IN PART
BY ANOTHER WEAK UPPER LOW MOVING S DOWN THE OREGON COAST. AS THIS
LOW MOVES S THE UPPER FLOW APPEARS LIKELY TO BECOME MORE NW AGAIN
LATER TODAY AND TONIGHT WHICH SHOULD LIMIT THE POTENTIAL FOR SHOWERS
TO SPREAD SO FAR W. WILL KEEP A SLIGHT CHANCE FOR SHOWERS THROUGH
THE MORNING OVER THE INTERIOR AREAS...THEN LIMIT THEIR CHANCES TO
THE CASCADES LATER TODAY AND TONIGHT. ONSHORE FLOW IS EXPECTED TO
CONTINUE THROUGH THE DAY TODAY...AND IN FACT THROUGH THE REST OF THE
SHORT TERM PERIOD. THIS WILL TEND TO KEEP PLENTY OF MARINE CLOUDS IN
OVER MOST OF THE FORECAST AREA FOR THE NEXT FEW DAYS...WITH PERHAPS
SOME LATE DAY BREAKS IN THE CLOUDS FOR SOME INLAND AREAS ESP IN THE
S. THE MARINE AIR AND CLOUDS WILL KEEP DAYTIME TEMPS NEAR NORMALS OR
A BIT ON THE COOLER SIDE OF NORMAL THROUGH MON. A CHANCE FOR MORNING
DRIZZLE WILL REMAIN ALONG THE COAST AND COAST RANGE THROUGH THIS
PERIOD...AND MAY SPREAD INLAND SUN AND MON MORNING AS ANOTHER UPPER
LOW CENTER DROPS S INTO WA BY MON.

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. MONDAY NIGHT
THROUGH FRIDAY...BY MONDAY NIGHT AN UPPER LEVEL LOW PRESSURE SYSTEM
WILL BE SLIDING GENERALLY THROUGH THE REGION...THOUGH CONFIDENCE IN
THE PRECISE TIMING AND TRACK REMAIN RELATIVELY LOW. MODELS SEEM TO
BE CLUSTERING ON A SOLUTION THAT DROPS THE LOW ALONG OR EAST OF THE
CASCADES AS IT MOVES SOUTH FROM CANADA...WHICH WILL PROVIDE FOR
PLENTY OF MARINE CLOUDS BUT KEEP MOST PRECIPITATION IN THE HIGHER
TERRAIN OF THE CASCADES. THEN...SHORTWAVE RIDGING WILL LIKELY BEGIN
TO BUILD OVER THE REGION FOR DRY CONDITIONS AND WARMING...
PARTICULARLY FOR THE SECOND HALF OF THE WEEK. WHILE MODEL SPREAD
REMAINS SOMEWHAT LARGE WITH RESPECT TO HOW HIGH HEIGHTS WILL
RISE...HIGH TEMPERATURES COULD CLIMB INTO THE LOWER 80S FOR THE
INTERIOR ON FRIDAY.  CULLEN
&&

.AVIATION...A SPREAD OF FLIGHT CONDITIONS ACROSS THE AREA AT THIS
HOUR. SOME SHOWERS AND WEAK MID LEVEL INSTABILITY REMAINS WITH A
SLIGHTLY MORE ORGANIZED LINE RUNNING JUST NORTH OF A KEUG-KONP
LINE AND MOVING SOUTH FOR THE NEXT FEW HOURS. FEEL INLAND CIGS
WILL LARGELY HOVER BETWEEN 025 AND 035 THROUGH EARLY AFTERNOON
BEFORE LIFTING TO BETWEEN 035 AND 050 FOR THE EVENING. MAY SEE THE
STRATUS GO SCATTERED LATER IN THE AFTERNOON BUT DO NOT HAVE ENOUGH
CONFIDENCE TO GO THAT STRONGLY AGAINST GUIDANCE. EVEN IF IT
DOES...FEEL THE CIGS WILL CLOSE BACK UP AROUND OR SHORTLY AFTER
SUNSET AROUND 345Z. COASTAL TERMINALS APPEAR TO BE ON THEIR WAY
TO WIDESPREAD IFR CIGS AS WAS PREVIOUSLY EXPECTED THOUGH KAST IS
TAKING THE LONGEST TO DROP AD HAS NOT QUITE REACHED THAT LOW YET.
THE COASTAL STRATUS OPTIMISTICALLY MAY BREAK UP A BIT AND LIFT
BACK TO 020-025 BUT WILL KEEP THEM CLOSER TO THE 015 AGL MARK AS A
PRELIMINARY THOUGH FOR THE 12Z TAF PACKAGE.

KPDX AND APPROACHES...CIGS BOUNCING BETWEEN 025 AND 035 WITH PATCHY
DRIZZLE/VERY LIGHT RAIN WILL CONTINUE UNTIL AROUND 19Z. FEEL CIGS
WILL LIFT AND BREAK UP SOMEWHAT THROUGH THE EARLY EVENING HOURS
BUT DO NOT EXPECT THEM TO RISE ABOVE THE 040 VISUAL APPROACH
THRESHOLD FOR MORE THAN A FEW HOURS THIS EVENING AT BEST. /JBONK

&&

.MARINE...PERSISTENT HIGH PRESSURE OFFSHORE AND LOW PRESSURE
INLAND BRINGS NORTHWEST TO NORTH WINDS ACROSS THE WATERS FOR THE
NEXT SEVERAL DAYS. NOT MUCH CONCERN FOR SPEEDS AS HIGHEST WIND
GUSTS STAY SEVERAL KTS BELOW THE 21 KT CRITERIA. WINDS OFF THE
BRITISH COLUMBIA COAST...HOWEVER...WILL BRING A CHOPPY FRESH
SWELL FOR THE NEXT COUPLE DAYS BEFORE A SLIGHTLY HIGHER AND LONGER
PERIOD WNW SWELL DOMINATES THE WATERS BEGINNING TUESDAY EVENING.
/JBONK

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND

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.


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