Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 210328
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
830 PM PDT SAT SEP 20 2014

.SYNOPSIS...AN AREA OF LOW PRES ALONG THE OREGON COAST WILL SHIFT
NORTHWARD AND OFFSHORE OVERNIGHT...CAUSING MARINE AIR TO SURGE N UP
THE COAST AND ULTIMATELY RESULTING IN COOLER TEMPS SPREADING IN SUN
AND MON. A WEAK FRONT WILL ALSO BRUSH BY MONDAY...POTENTIALLY
BRINGING A COUPLE SHOWERS TO THE COAST AND CASCADES. A STRONGER
FRONT WILL BRING A BETTER CHANCE FOR RAIN THROUGHOUT THE DISTRICT
LATE TUESDAY OR WEDNESDAY...FOLLOWED BY A COOL SHOWERY PATTERN FOR
THE REST OF THE WEEK.

&&

.SHORT TERM...CLOUDS SEEN IN SATELLITE PICTURE RACING N UP THE
CENTRAL OREGON COAST THIS EVENING. WITH THE SURFACE LOW ALREADY
APPROACHING KAST LATE THIS EVENING...EXPECT CLOUDS TO CONTINUE TO
SPREAD N UP THE OREGON COAST OVERNIGHT. AS THE LOW WEAKENS AND
SHIFTS OFFSHORE SUN THE INLAND PUSH ON THE CLOUDS WILL BE WEAK...
BUT A RIDGE OF HIGH PRES FORMING ALONG THE COAST LATE SUN WILL
INITIATE A STRONGER PUSH OF MARINE AIR INLAND SUN NIGHT.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...THE REAL COOLING
OCCURS INLAND ON MONDAY AS THE THERMAL TROUGH PRESENTLY LINGERING
WEST OF THE CASCADES SHIFTS OVER TO THE EAST SIDE. THIS WILL ALLOW
MORE PROLIFIC ONSHORE FLOW... PERHAPS EVEN SOME LOW CLOUDS INTO THE
WILLAMETTE VALLEY MON MORNING.

AT THE SAME TIME...A FRONTAL SYSTEM ALONG 145W WILL BE APPROACHING
THE PAC NW COAST. THERE IS GOOD AGREEMENT THAT THIS SYSTEM WILL
STRETCH APART WHILE APPROACHING THE COAST...WITH THE BULK OF LEFTOVER
ENERGY HEADED TOWARD BRITISH COLUMBIA. THE FRONT MAY HOLD TOGETHER
LONG ENOUGH FOR A COUPLE SHOWERS ALONG THE NORTH COAST OR IN THE
CASCADES MONDAY...BUT THAT IS ABOUT ALL. INCREASED CLOUD COVER AND
FALLING 500 MB HEIGHTS/850 MB TEMPS SHOULD HOLD TEMPS IN THE 70S FOR
MOST INLAND AREAS MON AFTERNOON.

THE MONDAY SYSTEM LIKELY LEAVES A DISORGANIZED BAROCLINIC ZONE DRAPED
ACROSS WESTERN WA/OR MON NIGHT/EARLY TUE. THIS COULD PROVIDE A
CONDUIT FOR A MORE ORGANIZED SYSTEM TO PUSH ONSHORE LATE TUE/WED. 12Z
GFS/ECMWF SEEM TO SHOW FAIRLY GOOD AGREEMENT THAT THERE WILL AT LEAST
BE A PERIOD OF RAIN THROUGHOUT OUR DISTRICT SOMEWHERE AROUND MIDWEEK
AS THIS OCCURS. RIGHT NOW LATE TUE/WED APPEARS TO BE MOST LIKELY.
DEPENDING ON HOW THIS SYSTEM SETS UP...IT COULD ALSO BE OUR FIRST
BREEZY SOUTH WIND EVENT OF THE SEASON ALONG THE COAST.WEAGLE

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. MODELS
CONTINUE TO SHOW A STRONG COLD FRONT MOVING IN FROM THE NORTHEAST
PACIFIC OCEAN ON TUESDAY BRINGING WIDESPREAD RAIN TO THE REGION ON
WEDNESDAY. AS THE SYSTEM MOVES ONSHORE WE COULD SEE PRECIPITABLE
WATER VALUES CONTINUING TO APPROACH 1.5 INCHES. WITH DECENT UPPER
LEVEL SUPPORT...PROVIDED BY A STRONG JET STEAK...SOME AREAS MY
RECEIVE OVER AN INCH OF RAIN. SEVERAL SHORTWAVES EMBEDDED WITHIN THE
MEAN LONGWAVE FLOW WILL LIKELY CONTINUE TO BRING UNSETTLED WEATHER
TO THE REGION...AT LEAST INTO FRIDAY. DECREASED POPS AND SKY COVER
SLIGHTLY NEXT WEEKEND DUE TO SLIGHT DIFFERENCES AND A DOWNWARD TREND
SHOWN BY THE VARIOUS MODELS. TEMPERATURES IN THE EXTENDED WILL
GENERALLY BE NEAR SEASONAL NORMALS. TJ/64

&&

.AVIATION...VFR CONDITIONS PERSIST INLAND THROUGH TONIGHT UNDER
OFFSHORE FLOW. HOWEVER OFFSHORE FLOW QUICKLY EASES TONIGHT AND
ONSHORE FLOW DEVELOPS SUNDAY AFTERNOON. SOUTHERLY MARINE SURGE IS
CURRENTLY WORKING ITS WAY NORTH ALONG THE OREGON COAST WITH
SOUTHERLY WINDS AND MARINE STRATUS AS FAR NORTH AS ABOUT NEWPORT
AS OF 03Z. EXPECT IFR AND LIFR CONDITIONS TO CONTINUE TO SPREAD
NORTH THROUGH THE NIGHT ALTHOUGH CIGS WILL TAKE LONGER TO SPREAD
INLAND TO AST THAN TO THE ADJACENT COAST.

KPDX AND APPROACHES...VFR CONDITIONS NEXT 24 HRS WITH OCCASIONAL
CEILING 5000-6000 FT DUE TO SMOKE. BOWEN

&&

.MARINE...NORTH WINDS CONTINUE TO EASE AS THE THERMAL TROUGH
EXPANDS OVER THE WATERS. SOUTHERLY WINDS WILL SPREADS ACROSS THE
WATERS BY MORNING...CURRENTLY AS FAR NORTH AS ABOUT BUOY
50...ACCOMPANIED BY SHALLOW LOW STRATUS AND FOG. AS DEVELOPING
WEAK LOW PRES CENTER MOVES UP OFFSHORE...GUSTS WILL LIKELY REACH
15 TO 20 KT SUNDAY AFTERNOON.

WESTERLY SWELL 6 TO 7 FT WILL PREVAIL TONIGHT...THEN SEAS SLOWLY
SUBSIDE OVER THE NEXT FEW DAYS. A MORE ACTIVE PATTERN WILL ARRIVE
MID WEEK WITH SMALL CRAFT OR HIGHER WINDS AND SEAS BUILDING TO
OVER 10 FT BY WEDNESDAY. BOWEN/27

&&

.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 AS THE FORECAST AREA.



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