797 
FXUS66 KPQR 021120
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
317 AM PST SUN MAR  2 2014

.SYNOPSIS...COLD HIGH PRESSURE HAS SETTLED INTO THE COLUMBIA BASIN
WITH LOWER PRESSURE THE OREGON COAST. AS A RESULT...EAST WINDS
CONTINUE TO PUSH COLD AIR THROUGH THE COLUMBIA GORGE...COLD ENOUGH
FOR WINTRY PRECIPITATION. TEMPERATURES ARE COLD ENOUGH FOR FREEZING
RAIN IN FAR EASTERN PORTIONS OF THE PORTLAND METRO THIS MORNING.
MILDER AIR WILL GRADUALLY PUSH IN AS LOW PRESSURE MOVES ONSHORE INTO
WASHINGTON TONIGHT AND EARLY MONDAY. THIS SYSTEM WILL ALSO BRING
GUSTY WINDS TO THE COAST AND WIDESPREAD RAIN ACROSS THE FORECAST
AREA. A SERIES OF POTENT PACIFIC FRONTAL SYSTEMS WILL THEN KEEP
THINGS WET AND WINDY AT TIMES FOR MUCH OF THE UPCOMING WEEK.

&&

.SHORT TERM...TONIGHT THROUGH TUESDAY...A SIGNIFICANT SNOW AND ICE
EVENT IS UNDERWAY IN THE COLUMBIA GORGE...AS TEMPERATURES ARE IN THE
MID TO UPPER 20S. AS MOST MODELS SUGGESTED YESTERDAY MORNING...COLD
HIGH PRESSURE HAS SETTLED INTO THE COLUMBIA BASIN WITH BRISK EASTERLY
FLOW THROUGH THE GORGE. COLD...DRY AIR IS DEEP ENOUGH TO PRODUCE SNOW
IN THE HOOD RIVER VALLEY FOR NOW. MEANWHILE THE COLD LAYER BECOMES
THINNER THE FURTHER WEST ONE GOES THROUGH THE GORGE. AS A
RESULT...FREEZING RAIN PREVAILS CASCADE LOCKS WESTWARD.

TEMPERATURES HAVE BEEN FALLING SLOWLY BUT STEADILY THROUGH THE NIGHT
IN EASTERN PORTIONS OF THE PORTLAND METRO AREA. CURRENTLY IT IS 31
DEGREES HERE AT THE OFFICE IN PARKROSE/NE PORTLAND. KTTD HAS REPORTED
SEVERAL HOURS OF -FZRA...AND IT APPEARS TO BE ACCUMULATING ACCORDING
TO THE ICE ACCRETION SENSOR. THE SENSOR IS SUGGESTING 0.15 INCH OF
ICE HAS ACCUMULATED AT THE AIRPORT. OTHER ACCOUNTS SUGGEST ICE IS
INDEED ACCUMULATING IN TROUTDALE AND GRESHAM...BUT NOT QUITE THAT
MUCH. THE ICE ACCRETION SENSOR IS MADE OF METAL...SO IT REPRESENTS
WHAT MAY BE ACCUMULATING ON THE COLDEST SURFACES. DESPITE TEMPS JUST
BELOW FREEZING SINCE 10 PM...THE ONLY FREEZING WE HAVE SEEN IS A
LITTLE BIT ON THE CARS IN OUR PARKING LOT AND METAL FENCES. THE ROADS
REMAIN WET HERE...BUT THERE HAVE BEEN SOME REPORTS ON SOCIAL MEDIA
THAT SURFACES ARE BECOMING SLICK IN TROUTDALE AND GRESHAM. SINCE
TEMPERATURES ARE NOT EXPECTED TO WARM UP EARLY THIS MORNING...AND
PRECIPITATION IS ONLY EXPECTED TO INCREASE...HAVE DECIDED TO ISSUE A
FREEZING RAIN ADVISORY FOR THE PORTLAND METRO AREA NEAR THE GORGE
UNTIL 10 AM.

THIS HAS ALL THE MAKINGS OF A SUBSTANTIAL SNOW AND ICE EVENT IN THE
GORGE...IN FACT THERE HAVE ALREADY BEEN SIGNIFICANT TRAVEL ISSUES
WITH THE RATHER LIGHT AMOUNTS OF PRECIPITATION RECEIVED SO FAR. LOW
PRESSURE IS STRENGTHENING NEAR 42N/134W...AND APPROACHING THE PAC NW
COAST. THIS SYSTEM WILL ONLY SERVE TO PULL MORE COLD...DRY AIR FROM
THE COLUMBIA BASIN INTO THE GORGE AS IT SPREADS STEADY RAIN ACROSS
THE ENTIRE FORECAST AREA. LOOKING AT HIGHER RESOLUTION MODELS SUCH AS
THE UW WRF-GFS AND OUR OWN 4 KM LOCAL WRF...AS WELL AS THE LOWER
RESOLUTION 12 KM NAM AND ECMWF...IT APPEARS GRADIENTS REMAIN EASTERLY
THROUGH THE GORGE INTO AT LEAST MIDDAY. THIS WILL SERVE TO LOCK THE
COLD AIR IN PLACE IN THE HOOD RIVER VALLEY...S WA CASCADE VALLEYS... 
AND THE MOUNT ADAMS AREA WHILE THE HEAVIEST PRECIPITATION STARTS TO 
FALL LATER TODAY. GIVEN THE PRECIPITATION THAT HAS ALREADY FALLEN... 
AND THE SNOW AND ICE EXPECTED TODAY...FEEL A WINTER STORM WARNING IS 
WARRANTED FOR THESE AREAS AS WELL AS THE WEST AND CENTRAL COLUMBIA 
GORGE. ALSO DECIDED TO ADD A FREEZING RAIN ADVISORY FOR THE NORTH 
OREGON CASCADES...MAINLY FOR THE PASSES AND THE EAST SIDE OF MOUNT 
HOOD.

THE CHANGEOVER TO PLAIN RAIN WILL LIKELY OCCUR SOMETIME THIS
AFTERNOON IN THE WEST GORGE...BUT AREAS FURTHER EAST WILL PROBABLY
NOT CHANGE OVER UNTIL THE UPPER TROUGH AXIS MOVES ACROSS THE CASCADES
THIS EVENING. THIS WILL SWITCH THE SFC PRESSURE GRADIENT AND OPEN UP
THE ENTIRE GORGE AND ADJACENT VALLEYS TO W-SW FLOW MONDAY...BRINGING
MUCH MILDER AIR AND AN END TO THE THREAT OF WINTRY PRECIP.

WILL NEED TO KEEP AN EYE ON RAINFALL TOTALS THIS WEEK...AS A SERIES
OF FAIRLY MOIST SYSTEMS MOVES ACROSS THE PAC NW. EACH SYSTEM HAS THE
POTENTIAL TO BRING 1-2 INCHES OF RAIN TO HIGHER TERRAIN...AND MODELS
SHOW REASONABLE AGREEMENT ON BRINGING ONE THROUGH EVERY 24-36 HRS. IT
APPEARS THE JUICIEST SYSTEM WILL COME MIDWEEK...AS MODELS SHOW IT
HAVING A STRONG TAP TO SUBTROPICAL MOISTURE. IF RAINFALL AND FAIRLY
HIGH SNOW LEVELS PAN OUT AS PRESENTLY EXPECTED...THERE COULD BE SOME
HYDROLOGIC ISSUES BY THE END OF THE WEEK.  WEAGLE 

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
TUESDAY NIGHT THROUGH SATURDAY...MILD BUT WET CONDITIONS ARE EXPECTED
NEXT WEEK AS STRONG WESTERLY FLOW PREVAILS. BOTH THE GFS AND ECMWF
REMAIN IN FAIR AGREEMENT SHOWING BACK TO BACK SYSTEMS MOVING THROUGH
THE REGION LATE TUESDAY AND ANOTHER LATE WEDNESDAY OR THURSDAY. THERE
ARE SOME NOTABLE DIFFERENCES...PRIMARILY CONCERNING THE STRENGTH AND
POSITION OF A SURFACE LOW WEDNESDAY NIGHT. THE ECMWF IS MAINTAINING A
MORE ORGANIZED SURFACE LOW FARTHER SOUTH THAN THE GFS...SUPPORTING A
CONTINUED CHANCE OF STRONG WINDS AT THE COAST AS THE LOW MOVES
ONSHORE WEDNESDAY NIGHT. WET WEATHER WILL CONTINUE THROUGH LATE WEEK
AS MODELS MAINTAIN AN UPPER LOW IN THE GULF OF ALASKA...WHICH WILL
KEEP WESTERLY FLOW INTO THE PAC NW. THERE MAY BE A BRIEF BREAK IN THE
RAIN ON FRIDAY AS UPPER LEVEL HIGH PRESSURE NOSES IN...BUT THE
ALASKAN GULF LOW LOOKS TO PRECLUDE ANY PERSISTENCE IN THE RIDGING.
LASTLY...AT THIS TIME THERE IS SOME POTENTIAL FOR CONVECTION TUESDAY
NIGHT THROUGH THURSDAY...PRIMARILY FOR THE NORTHERN PORTIONS OF THE
CWA. BB

&&

.AVIATION...NOT A GREAT DAY FOR FLYING IN THE REGION. WIDESPREAD
MVFR WITH POCKETS OF IFR WILL CHANGE LITTLE AS WARM FRONT LIFTS
ACROSS REGION LATER TODAY. MTNS REMAIN OBSCURED. LIGHT RAIN WILL
INCREASE AFTER 18Z FROM THE SW. AREAS OF IFR CIGS OVER THE
INTERIOR WILL IMPROVE A BIT...BUT WILL REMAIN MVFR. WORST WEATHER
REMAINS IN COLUMBIA GORGE AND EASTWARD...WHERE OCCASIONAL -FZRA
WILL CONTINUE INTO THE EVENING. ONCE FRONT LIFTS N THIS EVENING...
CIGS WILL GRADUALLY IMPROVE TO LOW VFR TONIGHT.

KPDX AND APPROACHES...LITTLE CHANGE IN CIGS TODAY. WARM FRONT WILL
PUSH INCREASING RAIN INTO AREA AFTER 16Z. CIGS WILL GRADUALLY
IMPROVE TO LOW VFR AFTER 04Z AS WARM FRONT LIFTS N OF KPDX. WILL
HAVE OCCASIONAL FREEZING RAIN BELOW 4000 FT IN E APPROACHES
THROUGH 20Z.					    ROCKEY. 

&&

.MARINE...WARM FRONT WILL LIFT N ACROSS REGION TODAY AND THIS
EVENING. WILL SEE INCREASING S WINDS BEHIND THE FRONT...WITH GUSTS
30 TO 35 KT AT TIMES. WITH WIND CHOP...COMBINED SEAS WILL BUILD UP
TO 8 TO 9 FT. WINDS RELAX LATER TONIGHT AS GRADIENT WEAKENS A BIT.

THE NEXT SIGNIFICANT FRONT ARRIVES LATE TUE INTO WED...WITH GOOD
POTENTIAL FOR SOUTHERLY GALES. UNSETTLED PATTERN CONTINUES THIS
WEEK WITH MORE FRONTS ARRIVING...WITH WINDS 25 TO 35 KT AT TIMES
AND SEAS RUNNING 9 TO 12 FT.				 ROCKEY.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR WESTERN 
     COLUMBIA RIVER GORGE.

     FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER 
     PORTLAND METRO AREA NEAR THE GORGE.

     WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR CENTRAL 
     COLUMBIA RIVER GORGE-UPPER HOOD RIVER VALLEY.

     FREEZING RAIN ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR 
     NORTHERN OREGON CASCADES.

WA...WINTER STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR WESTERN 
     COLUMBIA RIVER GORGE.

     FREEZING RAIN ADVISORY UNTIL 10 AM PST THIS MORNING FOR GREATER 
     VANCOUVER AREA NEAR THE GORGE.

     WINTER STORM WARNING UNTIL 10 PM PST THIS EVENING FOR CENTRAL 
     COLUMBIA RIVER GORGE-SOUTH WASHINGTON CASCADES.

PZ...GALE WARNING UNTIL 3 AM PST MONDAY FOR COASTAL WATERS FROM CAPE 
     SHOALWATER WA TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 8 AM    
     PST THIS MORNING.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 3 PM 
     THIS AFTERNOON TO 8 PM PST THIS EVENING.

&&

$$

MORE WEATHER INFORMATION ONLINE AT..
    HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
    WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
    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.