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 282204
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
204 PM PST WED JAN 28 2015

.SYNOPSIS...A WEAK FRONTAL BOUNDARY REMAINS DRAPED OVER NORTHWEST
OREGON BUT CONTINUES TO FALL APART. ONE MORE WEAK UPPER SHORT WAVE
ALONG THE COAST WILL CONTINUE TO MOVE ONSHORE THIS AFTERNOON AND
TONIGHT AND POSSIBLY PRODUCE A FEW LIGHT SHOWERS...THEN DRIFT SOUTH
OF THE AREA LATER THURSDAY AND THURSDAY NIGHT. ANOTHER UPPER LEVEL
RIDGE IS EXPECTED TO DEVELOP OVER THE PACIFIC NORTHWEST THURSDAY
NIGHT AND FRIDAY AND CONTINUE OVER THE AREAS THROUGH SATURDAY FOR
MORE DRY AND RATHER MILD WEATHER...A BIT OF EASTERLY WINDS THROUGH
THE GORGE...BUT WITH AREAS OF FOG AND STABLE CONDITIONS BELOW
TEMPERATURE INVERSIONS IN MOST OF THE VALLEY AREAS. THE NEXT CHANCE
FOR RAIN IS PROBABLY NOT UNTIL SUNDAY AND MONDAY.
&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...THE BOUNDARY THAT HAS BEEN
OVER PARTS OF SOUTHWEST WASHINGTON LATE TUESDAY INTO THIS MORNING HAS
CONTINUED TO FALL APART AND THERE ARE NOT MANY CLOUDS LEFT. THE MAIN
CLOUDS ARE THE PERSISTENT VALLEY LOW CLOUDS AS WELL AS SOME HIGHER
CLOUDS ASSOCIATED WITH AN UPPER SHORT WAVE ALONG THE COAST.

THE UPPER SHORT WAVE ALONG THE COAST WILL BE OVER OUR FORECAST AREA
TONIGHT INTO EARLY THURSDAY...THEN SLOWLY BEGIN TO SLIDE SOUTHEAST
DURING THE DAY THURSDAY AND MOVE OUT OF THE AREA THURSDAY NIGHT. WILL
CONTINUE TO KEEP A SMALL CHANCE OF SHOWERS INTO THURSDAY MORNING AS
THIS FEATURE MOVES THROUGH THOUGH CONFIDENCE OF ANY SHOWERS HITTING A
RAIN GAGE IS NOT HIGH. WILL ALSO KEEP CLOUDS OVER THE AREA FROM IT AS
WELL.

THE CLOUDS WILL FINALLY COLLAPSE AND CLEAR THURSDAY NIGHT AS THE
UPPER SHORT WAVE MOVES AWAY AND AN UPPER RIDGE STARTS TO MOVE IN.
EXPECT AREAS OF FOG TO REDEVELOP THURSDAY NIGHT AND CONTINUE THROUGH
AT LEAST FRIDAY MORNING ESPECIALLY IN THE VALLEYS. WILL SEE SOME
MODEST EAST WINDS THROUGH THE GORGE AS WELL THURSDAY NIGHT AND
FRIDAY...THAT MAY BRING SOME CLEARING TO AT LEAST THE NORTH VALLEY
AREAS FRIDAY AFTERNOON. NOT MUCH CHANGE IN THE PATTERN FROM FRIDAY TO
SATURDAY...WITH VALLEY FOG CONTINUING AND ALSO MORE MODEST EAST WIND
NEAR THE GORGE. TOLLESON

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...THE UPPER RIDGE
BEGINS TO SHIFT INLAND SATURDAY NIGHT AS A LARGE LOW PRESSURE SYSTEM
REMAINS IN THE CENTRAL NORTH PACIFIC. MODELS REMAIN IN GOOD AGREEMENT
THAT A MOIST FRONTAL SYSTEM MOVES INTO THE REGION SUNDAY WITH PLENTY
OF SHOWERS CONTINUING INTO EARLY MONDAY. SNOW LEVELS LOWER A BIT BUT
STILL LOOK TO REMAIN WELL ABOVE THE CASCADE PASSES. ANOTHER FRONT MAY
ARRIVE AROUND TUESDAY. MODEL SOLUTIONS THEN DIVERGE A BIT FOR
MIDWEEK...WITH THE ECMWF CONTINUING A STREAM OF MOISTURE INTO THE
REGION WHILE THE GFS REBUILDS A RIDGE OVER THE AREA AND PUSHES THE
MOISTURE NORTH. GIVEN THIS UNCERTAINTY...AND THE FACT THAT THE GFS
ENSEMBLE MEMBERS MAINTAIN A WIDE RANGE ENCOMPASSING BOTH OF THESE
SOLUTIONS...OPTED TO BLEND AND MAINTAIN CHANCE POPS FOR TUESDAY AND
WEDNESDAY.  CULLEN
&&

.AVIATION...IFR/MVFR STRATUS REMAINS OVER MOST OF THE WILLAMETTE
VALLEY THIS AFTERNOON...EXCEPT FOR THE FAR SOUTH NEAR KEUG. THE
STRATUS IS SLOWLY LIFTING AND THINNING...AND THINK THERE IS A DECENT
CHANCE THAT CONDITIONS WILL IMPROVE TO VFR LATER THIS AFTERNOON FOR
MOST OF THE VALLEY. HOWEVER ANY IMPROVEMENT WILL LIKELY BE
SHORT-LIVED...AS IFR OR LOWER STRATUS AND FOG WILL LIKELY FORM OVER
THE LOWLANDS AGAIN AFTER 03Z THU. EASTERLY WINDS ARE EXPECTED TO
DEVELOP THROUGH THE COLUMBIA RIVER GORGE THIS EVENING AND STRENGTHEN
OVERNIGHT...WHICH WILL LIKELY KEEP KTTD VFR TONIGHT AND POTENTIALLY
THE COASTAL TAF SITES AS WELL. EXPECT THE FOG AND LOW STRATUS IN THE
VALLEY TO DISSIPATE MORE QUICKLY TOMORROW AS NORTHERLY FLOW DEVELOPS
ACROSS THE REGION. THE EXCEPTION MAY BE KEUG...WHERE THE NORTHERLY
WINDS TEND TO KEEP LOW STRATUS LOCKED IN PLACE LONGER THAN IN OTHER
VALLEY LOCATIONS.

KPDX AND APPROACHES...IFR STRATUS DECK IS SLOWLY LIFTING AND THINNING
THIS AFTERNOON. THINK THERE IS A BETTER THAN 50 PERCENT CHANCE OF
SEEING A PERIOD OF VFR CONDITIONS LATER THIS AFTERNOON. DEVELOPING
EASTERLY WINDS TONIGHT WILL LIKELY KEEP AREAS AROUND THE WEST END OF
THE GORGE VFR OVERNIGHT...BUT DO NOT THINK WINDS WILL BE STRONG
ENOUGH TO KEEP FOG AND LOW CLOUDS FROM REFORMING AT KPDX AFTER 03Z.
EXPECT IFR OR MVFR CONDITIONS OVERNIGHT...BUT SHOULD SEE CONDITIONS
IMPROVE BY MID-MORNING THU. PYLE
&&

.MARINE...A LOW PRES CIRCULATION IS APPARENT IN SATELLITE IMAGERY
ABOUT 220 NM WEST OF NEWPORT THIS AFTERNOON. THIS LOW IS LIFTING A
WEAK WARM FRONT NORTHWARD THROUGH THE WATERS...BUT THIS IS HAVING
LITTLE IMPACT ON THE SENSIBLE WEATHER. THE LOW WILL MOVE INTO THE
NORTHERN WASHINGTON COASTAL WATERS TONIGHT...ALLOWING HIGH PRES TO
BUILD OVER THE NE PAC FOR THE NEXT FEW DAYS. AT THE SAME TIME THERMAL
LOW PRES WILL STRENGTHEN OVER N CALIFORNIA...SETTING UP A SUMMER-LIKE
NORTHERLY FLOW PATTERN OVER THE REGION THROUGH SAT. EXPECT WINDS TO
REMAIN BELOW 20 KT DURING THIS TIME. SEAS WILL ALSO REMAIN WELL BELOW
10 FT.

THE NEXT FRONTAL SYSTEM APPEARS TO BE ON TAP FOR SAT NIGHT INTO EARLY
SUN. THIS SYSTEM APPEARS TO WEAKEN SIGNIFICANTLY BEFORE IT NEARS
SHORE...AND ASSOCIATED WINDS ARE NOT MODELED TO REACH SMALL CRAFT
CRITERIA. A SECOND STRONGER FRONT IS BEING ADVERTISED FOR SUN NIGHT
INTO MON. THEN A MORE ACTIVE PATTERN APPEARS POSSIBLE FOR NEXT
WEEK...ALTHOUGH CONFIDENCE IN THE DETAILS IS LOW AT THIS TIME. PYLE
&&

.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.


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