Damaging Wind in Oregon, November 22, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
929 AM PST SAT NOV 22 2014

.SYNOPSIS...POST FRONTAL SHOWERS UNDER A COOLER AIR
MASS THROUGH TONIGHT...WITH SNOW LEVELS JUST BELOW THE
CASCADE PASSES. UPPER LEVEL HIGH PRESSURE WILL STRENGTHEN OVER THE NE
PAC BEGINNING LATE SUN INTO MON. HOWEVER...SEVERAL LOW PRES SYSTEMS
MOVING THROUGH TO THE NORTH WILL KEEP PRECIPITATION CHANCES AROUND AT
TIMES THROUGH MIDWEEK.

&&

.SHORT TERM...A LINE OF THUNDERSTORMS PUSHED ONSHORE THIS MORNING
PROVIDING SEVERAL LIGHTNING STRIKES FOR THE IMMEDIATE COAST. THIS
BAND HAS NOW PUSHED INLAND AND IS CURRENTLY OVER THE WILLAMETTE
VALLEY. THE THUNDERSTORMS HAVE NOT CONTINUED AS THE BAND MOVED INLAND
AS THE WARMER SEA SURFACE TEMPERATURES PROBABLY ADDED TO THE
INSTABILITY AND HELPED TRIGGER THE COASTAL STORMS. THE INSTABILITY
MAY INCREASE THIS AFTERNOON AS THE SURFACE TEMPERATURES WARM AND WILL
CONTINUE THE SLIGHT CHANCE FOR THUNDERSTORMS FROM THE COAST THROUGH
THE EAST EDGE OF THE WILLAMETTE VALLEY THROUGH THE LATE AFTERNOON.

SNOW LEVELS HAVE LOWERED THIS MORNING WITH SURFACE OBSERVATIONS AND
WEB CAMS SUGGESTING THE SNOW LEVEL IS CURRENTLY AROUND 4500 FEET. WEB
CAMS SHOW ACCUMULATING SNOW FOR THE SANTIAM AND WILLAMETTE PASSES.
THE RAIN BAND THAT IS OVER THE WILLAMETTE VALLEY NOW WILL MOVE OVER
THE CASCADES LATER THIS MORNING...AND HELP SNOW TOTALS FOR THE
CASCADES. THE WINTER WEATHER ADVISORY LOOKS ON TRACK FOR 5-10 INCHES
OF SNOW ABOVE 3500-4000 FT AND POSSIBLY A FOOT OF SNOW ABOVE 5000 FT
BY TONIGHT.

THERE WILL BE A BREAK IN PRECIPITATION TONIGHT BEFORE ANOTHER FRONT
MOVES IN FROM THE NORTH EARLY SUNDAY MORNING. THIS FRONT WILL BRING
MORE ACCUMULATING SNOW TO THE CASCADES...ESPECIALLY THE SOUTH
WASHINGTON CASCADES...THROUGH SUNDAY AFTERNOON. SNOW LEVELS SHOULD
REMAIN JUST BELOW THE CASCADE PASSES...AROUND 4500 FEET. THERE WILL
NOT BE AS MUCH PRECIPITATION...AND DO NOT ANTICIPATE THE NEED FOR
ANOTHER WINTER WEATHER PRODUCT. HOWEVER...WE WILL TAKE A CLOSER LOOK
AT THE POTENTIAL SNOW TOTALS WITH THIS AFTERNOON'S FORECAST PACKAGE.
TJ

FOR THE LOWER ELEVATIONS...EXPECT A FAIRLY MILD AND SEASONAL WEEKEND.
THERE WILL BE PLENTY OF SHOWERS AROUND...BUT DO NOT EXPECT
SIGNIFICANT QPF TOTALS AS A DIRTY RIDGE REMAINS SITUATED OVER THE
PACIFIC NORTHWEST INTO EARLY NEXT WEEK. THE NEXT SIGNIFICANT FRONTAL
SYSTEM RIDES OVER THE UPPER LEVEL RIDGE AND DROPS INTO THE FORECAST
AREA EARLY TUESDAY. HEAVY PRECIPITATION WILL LIKELY IMPACT THE
NORTHERN ZONES. TJ/27

.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY...EXTENDED MODELS HOLD
ONTO THE UPPER LEVEL RIDGE OVER THE REGION THROUGH MID-WEEK...YET THE
GFS IS ATTEMPTING TO FLATTEN THE RIDGE MORE SO THAN THE ECMWF TUESDAY
NIGHT INTO WEDNESDAY. THIS WOULD MEAN THE PACIFIC NORTHWEST WOULD
REMAIN UNDER DAMP AND COOLER CONDITIONS...WHILE THE ECMWF HAS
STRENGTHENED THE RIDGE AND BREAK IT DOWN LATER IN THE WEEK WITH
ANOTHER PACIFIC FRONT. HAVE TRENDED TOWARDS THE GFS WHICH WOULD
MAINTAIN A THREAT FOR LIGHT SHOWERS ACROSS THE REGION. THIS SHOULD
KEEP SEASONAL WEATHER AROUND FOR THE THANKSGIVING TRAVEL PERIOD AS NO
SIGNIFICANT WEATHER SYSTEMS ARE CURRENTLY ANTICIPATED. PYLE/27

&&

.AVIATION...WITH PLENTY OF LOW LEVEL MOISTURE IN PLACE...A FEW
AREAS OF IFR/MVFR FOG AND LOW STRATUS MANAGED TO FORM EARLY THIS
MORNING. HOWEVER...CONDITIONS HAVE IMPROVED TO PREDOMINANTLY VFR
OVER THE PAST HOUR. WE WILL REMAIN IN A SHOWERY PATTERN THROUGH
THE WEEKEND. WITH A FAIRLY UNSTABLE AIR MASS IN PLACE...EXPECT
MAINLY VFR CONDITIONS THROUGH TONIGHT...WITH BRIEF PERIODS OF
MVFR OR IFR POSSIBLE DURING ANY HEAVIER SHOWERS. THERE IS ALSO A
SLIGHT POSSIBILITY OF THUNDERSTORMS THROUGH THIS AFTERNOON...WITH
THE BEST THREAT ALONG THE COAST. BASED ON THE PATCHY FOG THAT WAS
OBSERVED THIS MORNING...CANNOT RULE OUT A SIMILAR SCENARIO FOR
EARLY SUN MORNING. WILL ADD A BRIEF PERIOD OF MVFR/IFR FOG OR LOW
STRATUS FOR WITH THE 18Z SET OF TAFS.

KPDX AND APPROACHES...A POST FRONTAL SHOWERY AIR MASS WILL LEAD
TO PREDOMINANTLY VFR CONDITIONS THROUGH TONIGHT. AN OCCASIONAL
BRIEF MVFR FLIGHT RESTRICTION WILL BE POSSIBLE DURING ANY HEAVIER
SHOWERS. PATCHY MVFR/IFR FOG OR LOW STRATUS MAY AFFECT THE
TERMINAL EARLY SUN MORNING. PYLE

&&

.MARINE...EXPECT OCCASIONAL GUSTS TO 25 KT...POSSIBLY EVEN 30 KT
TODAY ACROSS THE WATERS...BUT IN GENERAL WINDS SHOULD BE ON THE
DECREASE. SEAS WILL REMAIN IN THE LOW TEENS TODAY AND TONIGHT.
ANOTHER FRONT CURRENTLY OFF THE QUEEN CHARLOTTE ISLANDS WILL SKIRT
THE WATERS ON SUNDAY AND BRING WIND GUSTS BACK UP INTO THE 25 TO
30 KT RANGE. SEAS WILL RESPOND ACCORDINGLY AND RISE BACK INTO THE
MID TEENS ON SUNDAY. YET ANOTHER FRONT WILL AFFECT THE WATERS ON
MON...LIKELY BRINGING ANOTHER ROUND OF SMALL CRAFT ADVISORY WINDS
AND KEEPING SEAS ABOVE 10 FT. SEAS SHOULD FINALLY DROP BELOW 10 FT
BY TUE OR WED AS HIGH PRES BUILDS OVER THE NORTHEAST PACIFIC. A
SLOWER MOVING PACIFIC FRONTAL SYSTEM MAY IMPACT THE WATERS LATE IN
THE WEEK. PYLE/NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR CASCADES
     IN LANE COUNTY-NORTHERN OREGON CASCADES.

WA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT PST TONIGHT FOR SOUTH
     WASHINGTON CASCADES.

PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 PM PST THIS AFTERNOON FOR

     COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST SUNDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT 60
NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 4 PM PST
     SUNDAY.

&&

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.