Area Forecast Discussion
Issued by NWS Portland, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KPQR 140501
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 PM PST SAT FEB 13 2016

.SYNOPSIS...A WARM FRONT APPROACHING THE COAST WILL BRING CONTINUED
RAIN OVERNIGHT WITH RISING SNOW LEVELS. THE FRONTAL ZONE WILL LINGER
OVER THE AREA SUNDAY...THEN LIFT NORTH SUNDAY NIGHT AND MONDAY FOR
DECREASING RAIN. HIGH PRESSURE WILL BRING DRIER WEATHER LATER MONDAY
INTO TUESDAY...ESPECIALLY FOR SOUTHERN ZONES. AN UPPER LEVEL TROUGH
IS EXPECTED TO BRING COOLER AND SHOWERY WEATHER LATER WEDNESDAY INTO
THURSDAY...WITH SNOW POSSIBLE FOR THE CASCADE PASSES AND ABOVE.

&&

.SHORT TERM...SATELLITE SHOWED TROPICAL MOISTURE SPREADING INTO THE
PACIFIC NW THIS EVENING...WITH PRECIPITABLE WATER VALUES EXPECTED TO
APPROACH 1.2 INCHES ALONG THE OREGON COAST TONIGHT. H8 WINDS WERE
STRONG THIS EVENING NEAR 50KT ALONG THE N OREGON COAST IN THE GFS
ANALYSIS...BUT MODELS CONTINUED TO INDICATE WEAKENING W WINDS
OVERNIGHT LEADING TO DIMINISHING MOISTURE TRANSPORT. WITH THE
WESTERLY FLOW...RAINFALL THIS EVENING HAS BEEN HEAVIEST OVER THE N
PART OF THE W SLOPES IN THE CASCADES...COAST RANGE AND WILLAPA
HILLS. DEEP MOIST ISENTROPIC LIFT THOUGH WILL KEEP POPS HIGH
THROUGHOUT THE REGION INTO SUN. WITH THE CLOUDS AND WARM AIR
ADVECTION TEMPS ARE NOT LIKELY TO FALL MUCH OVERNIGHT. WITH THE
WESTERLY FLOW AND WARM AIR ADVECTION...MODELS CONTINUE TO INDICATE
RISING SNOW LEVELS OVERNIGHT. OBSERVATIONS ON MT HOOD SUGGEST SNOW
LEVEL STILL IN THE 4000 TO 4500 FT RANGE LATE THIS EVENING...SO WILL
RUN THE WINTER WX ADVISORIES FOR THE N OREGON AND S WA CASCADES
THROUGH 12Z.

REMAINDER OF SHORT TERM DISCUSSION UNCHANGED...UPPER LEVEL RIDGING
WILL BEGIN BUILDING IN FROM THE SW SUNDAY...BUT WEAK SHORTWAVES WILL
LIKELY RIDE OVER THE TOP OF THE RIDGE AND REMAIN INTACT TO KEEP SOME
RAIN IN THE PICTURE THROUGH SUN EVENING. DRYING TREND IS EXPECTED
MON/TUE AS THE UPPER RIDGE SHOVES THE MAIN BAROCLINIC ZONE NORTHWARD
INTO WA/BC. SW WA MAY REMAIN CLOSE ENOUGH TO THE FRONTAL ZONE TO
KEEP SOME RAIN OR DRIZZLE AROUND...BUT AREAS PDX METRO SOUTHWARD
SHOULD BE MAINLY DRY MON/TUE. STRENGTHENING INVERSIONS MAY PROMOTE
NIGHT AND MORNING FOG... ESPECIALLY SOUTH OF SALEM WHERE SKIES HAVE
THE BEST CHANCE OF CLEARING. ANY FOG THAT DOES DEVELOP MAY BE
STUBBORN. DID NOT FACTOR THIS INTO MON/TUE MAX TEMP FORECASTS
YET...AS THERE REMAINS A GOOD DEAL OF UNCERTAINTY AS TO IF AND WHERE
FOG WILL DEVELOP.  WEAGLE

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS. TUESDAY NIGHT
THROUGH FRIDAY...THE UPPER RIDGE RESPONSIBLE FOR THE DRYING TREND
MON/TUE WILL SHIFT EAST MIDWEEK... WITH MODELS SHOWING GOOD
CONSENSUS IN BRINGING A WELL DEFINED UPPER TROUGH INTO THE PAC NW
AND POSSIBLY CALIFORNIA WED NIGHT/THU. THIS WILL CAUSE RAIN CHANCES
TO INCREASE LATER WED...WITH COOL AND SHOWERY WEATHER LINGERING INTO
THU. AIR MASS WILL START OUT RATHER WARM WITH SNOW LEVELS WELL ABOVE
THE CASCADE PASSES WED. COLDER AIR WILL MOVE IN WITH THE UPPER
TROUGH...WITH SNOW LEVELS LOWERING TO 3000 TO 3500 FEET IN SHOWERS
BY THURSDAY. EXPECT TEMPS TO DROP BACK TO NEAR NORMAL LATE WEEK AS A
RESULT OF THE UPPER TROUGH...POSSIBLY EVEN A LITTLE BELOW NORMAL.
MODELS SHOW DECENT AGREEMENT THAT THIS UPPER TROUGH WILL BE FOLLOWED
BY A MORE PROGRESSIVE FRONTAL SYSTEM FOR MORE RAIN AND CASCADE SNOW
FRI/FRI NIGHT.  WEAGLE

&&

.AVIATION...WARM FRONTAL RAIN TO CONTINUE OVERNIGHT. THIS WILL
KEEP THE COAST MAINLY MVFR WITH POCKETS OF IFR. THE INTERIOR WILL
LIKELY BE A MIX OF MVFR AND VFR CONDITIONS. THE RAIN SHOULD BECOME
MORE CONFINED TO THE COAST AND HIGHER TERRAIN TOMORROW AS THE WARM
FRONT LIFTS NORTHWARD. CONDITIONS MAY TREND TOWARD VFR OVER THE
INTERIOR DURING THE LATE MORNING AND AFTERNOON...BUT EXPECT MVFR
TO REMAIN AT THE COAST THROUGH THE DAY. EXPECT THE MOUNTAINS TO
REMAIN OBSCURED THROUGH SUN AS STRONG 850 MB FLOW RESULTS IN
ENHANCED OROGRAPHIC LIFT.

KPDX AND APPROACHES...EXPECT A MIX OF MVFR AND VFR CONDITIONS AS
RAIN CONTINUES TONIGHT INTO SUN MORNING. CONDITIONS MAY IMPROVE TO
MAINLY VFR LATER SUN MORNING AND SUN AFTERNOON. PYLE

&&

.MARINE...GUSTY SOUTHERLY WINDS ACCOMPANIED THE ARRIVAL OF A
FRONTAL SYSTEM EARLIER THIS AFTERNOON AND EVENING. THE FRONT IS
MOVING ONSHORE NOW...AND WINDS HAVE SWITCHED TO THE SOUTHWEST
OVER MOST OF THE COASTAL WATERS BEHIND THE FRONTAL PASSAGE. THE
STRONGEST WINDS ARE NOW OVER...BUT WILL MAINTAIN A GALE WARNING
FOR THE NORTHERN INNER WATERS...ZONE PZZ250 THROUGH 10 PM. EXPECT
SW WINDS 15 TO 20 KT WITH GUSTS TO 25 KT TO CONTINUE OVERNIGHT AND
THROUGH MOST OF SUNDAY. BREEZY SW WINDS TO CONTINUE AT TIMES MON
INTO EARLY TUE BEFORE WINDS EAST LATER TUE. ANOTHER SYSTEM ARRIVES
WED AND THU. THERE ARE CONSIDERABLE UNCERTAINTIES IN THE FCST
MODELS FOR THE SECOND HALF OF THE WEEK...BUT IT APPEARS THAT THERE
WILL BE POTENTIAL FOR GALES AT TIMES.

A LONG PERIOD NW SWELL WILL MAINTAIN SEAS 12 TO 15 FT THROUGH
TONIGHT AS THE WIND WAVE COMPONENT INCREASES. SEAS WILL SUBSIDE
TO AROUND 10 FT SUN AFTERNOON. LATEST ENP RUN HAS SEAS INCREASING
TO NEAR 15 FT LATE NEXT WEEK AND POSSIBLY NEAR 20 FT NEXT WEEKEND.
WANT TO SEE A FEW MORE RUNS BEFORE GOING THAT HIGH. CAPPED SEAS TO
AROUND 15 FT FOR NOW. PYLE/WEISHAAR

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 4 AM PST SUNDAY FOR NORTHERN
     OREGON CASCADES.

WA...WINTER WEATHER ADVISORY UNTIL 4 AM PST SUNDAY FOR SOUTH
     WASHINGTON CASCADES.

PZ...GALE WARNING UNTIL 10 PM PST THIS EVENING FOR COASTAL WATERS
     FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 10 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 4 AM PST MONDAY FOR WATERS
     FROM CAPE SHOALWATER WA TO CASCADE HEAD OR FROM 10 TO 60 NM.

     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM PST SUNDAY
     FOR COASTAL WATERS FROM CASCADE HEAD TO FLORENCE OR OUT 10
     NM-WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR FROM
     10 TO 60 NM-WATERS FROM CASCADE HEAD TO FLORENCE OR FROM 10
     TO 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 6 PM PST SUNDAY FOR COASTAL
     WATERS FROM CASCADE HEAD OR TO FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 10 AM 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.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.