Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 310449
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
849 PM PST FRI JAN 30 2015

.SYNOPSIS...AN UPPER RIDGE AND OFFSHORE FLOW WILL PRODUCE RELATIVELY
MILD TEMPERATURES FOR JANUARY...WITH AREAS OF VALLEY FOG AND EAST
WINDS NEAR THE MOUTH OF THE COLUMBIA RIVER GORGE THROUGH SATURDAY
NIGHT. EXPECT A DECENT SHOT OF RAIN IN SOUTHWEST WASHINGTON AND
NORTHWEST OREGON SUNDAY INTO SUNDAY EVENING AS A PACIFIC FRONT MOVES
THROUGH. ANOTHER GOOD SHOT OF RAIN APPEARS LIKELY ON MONDAY AS
ANOTHER PACIFIC LOW AND FRONT MOVES BY. SOME MORE RAIN IS POSSIBLE
MID WEEK FROM A WARM FRONT THOUGH CONFIDENCE IN THE DETAILS AND
TIMING IS LOW. A SERIES OF WETTER COLD FRONTS IS LIKELY LATE NEXT
WEEK INTO NEXT WEEKEND. SIGNIFICANT SNOWS AT CASCADE PASS LEVEL
APPEAR UNLIKELY DURING THE NEXT WEEK.
&&

.UPDATE...ONLY SUBTLE FUSSING WITH THE FORECAST TONIGHT AS WE START
OUT WITH SOMEWHAT SIMILAR CONDITIONS TO LAST NIGHT. AS MENTIONED
BELOW...EASTERLY GRADIENTS WILL BE A LITTLE LIGHTER THAN LAST NIGHT
WHILE NORTHERLY GRADIENTS ALONG THE WILLAMETTE VALLEY ARE FAIRLY
SIMILAR. HAVE NUDGED TONIGHT`S FOG/STRATUS COVERAGE TOWARD WHAT WAS
OBSERVED EARLIER TODAY BUT ALLOWED FOR SOME FOG/STRATUS COVERAGE
DEVELOPMENT ACROSS THE REMAINDER OF THE I-5 CORRIDOR AND THE CENTRAL
VALLEY. STRONGER SUBSIDENCE HAS STRENGTHENED THE INVERSIONS BY A FEW
DEGREES SO UPPED MIDSLOPE TEMPERATURES CORRESPONDINGLY. ALSO SEEING
DRIER AIR OVERALL UNDER THE SUBSIDENCE. FOR EXAMPLE THE FREEZING
LEVEL IS NEAR 9000 FEET WITH A DEW POINT OF -56 AND A CORRESPONDING
RH OF 1 (ONE) PERCENT. FORTUNATELY...LOWER LEVELS ARE STILL IN MUCH
BETTER SHAPE BUT DO EXPECT THE LOW LEVEL INVERSION WILL RESULT IN
SOME SUMMERTIME LIKE TEMPERATURE AND HUMIDITY PROFILES THROUGH
SATURDAY. BE CAREFUL TOMORROW WITH BURNING SLASH AND YARD DEBRIS IF
ABOVE THE INVERSIONS AND OUT OF THE FOG/STRATUS. FIRE MAY GET MORE
ACTIVE THAN ONE MIGHT EXPECT FOR THIS TIME OF YEAR. UPDATES WILL BE
AVAILABLE SHORTLY.
/JBONK

&&

.PREV DISC... /ISSUED 221 PM PST FRI JAN 30 2015/

SHORT TERM...TONIGHT THROUGH MONDAY...THE PATTERN OF FOG AND LOW
CLOUDS THIS AFTERNOON IS PRETTY MUCH WHAT WE SAW THURSDAY AFTERNOON
JUST BEFORE IT ALL CLEARED...AND EXPECT IT TO MOSTLY CLEAR AGAIN THIS
AFTERNOON AND EARLY EVENING. THERE WAS A BIT OF A LULL IN THE
GRADIENT THROUGH THE GORGE THIS MORNING BUT THE GRADIENT IS BACK UP
TO 6.3 MB EARLY THIS AFTERNOON. THE NAM12 MODEL SAYS THE GRADIENT IS
GOING TO WEAKEN A BIT AGAIN TONIGHT AND EARLY SATURDAY...AND IF IT
DOES...THE FOG COVERAGE TONIGHT AND SATURDAY MORNING WOULD BE A BIT
MORE EXTENSIVE THAN THIS MORNING...AND HAVE TRENDED THE GRIDS THAT
WAY. WOULD ALSO EXPECT A BIT SLOWER CLEARING SATURDAY AFTERNOON. BUT
CONFIDENCE IN THAT IS ONLY MODERATE AT BEST AS THE LOW CLOUDS IN THE
COLUMBIA BASIN REMAIN SOLID AND THIS WOULD SUGGEST THE WINDS MIGHT
NOT CHANGE TOO MUCH.

THE GRADIENT THROUGH THE GORGE INCREASES LATE SATURDAY AND SATURDAY
NIGHT AS THE HIGH PRESSURE EAST OF THE CASCADES STRENGTHENS SOME DUE
TO THE PASSAGE OF A WEAK SYSTEM WELL TO OUR NORTH AND EAST. THIS MAY
AFFECT THE FOG FORMATION SOME NEAR PORTLAND AND VANCOUVER...BUT THE
REST OF THE VALLEY AREAS SHOULD SEE MORE FOG AGAIN OVERNIGHT SATURDAY
NIGHT.

THE MODELS ARE SHOWING THE NEXT FRONTAL SYSTEM APPROACHING THE NORTH
COASTAL AREAS LATE SATURDAY NIGHT AND MOVING THROUGH SOUTHWEST
WASHINGTON AND NORTHWEST OREGON DURING THE DAY SUNDAY AND EARLY
SUNDAY EVENING. SPED UP THE ARRIVAL OF THE PRECIPITATION UP A TOUCH
AND RAISED POPS PREVIOUSLY IN THE MORNING UPDATE. WE SHOULD SEE A
DECENT SHOT OF QPF FROM THIS SYSTEM...WITH THE HIGHER TERRAIN SEEING
A HALF INCH OR MORE AND THE VALLEYS MAYBE A QUARTER OF AN INCH. A BIT
WETTER SYSTEM IS EXPECTED MONDAY...WITH AMOUNTS A BIT HIGHER THAN ON
SUNDAY...MAYBE ONE AND A HALF TO TWO TIMES HIGHER. MAY SEE SOME
BREEZES ON THE COAST MONDAY AS A 1005 MB SURFACE LOW HEADS TOWARD
VANCOUVER ISLAND. UNFORTUNATELY...SNOW LEVELS REMAIN RATHER HIGH WITH
THESE SYSTEMS...WITH ANY SNOW IN THE HIGHER CASCADES IN THE NORTH
PART OF OUR FORECAST AREA. TOLLESON

LONG TERM...MONDAY NIGHT THROUGH FRIDAY...IN THE WAKE OF THE SYSTEM
THAT MOVES THROUGH MONDAY...THE MODELS DEVELOP A WARM FRONT AND
ATTEMPT TO EVENTUALLY LIFT IT NORTH THROUGH THE PACIFIC NORTHWEST IN
THE MID WEEK PERIOD. UNFORTUNATELY...THE MODELS ARE HAVING A TOUGH
TIME SETTLING ON WHEN AND WHERE IT WILL FORM AND HOW WET IT WILL BE.
IT WILL LIKELY FORM SOMEWHERE OVER SOUTHWEST OREGON OR EXTREME
NORTHERN CALIFORNIA...THEN LIFT NORTH AROUND WEDNESDAY. FOR NOW HAVE
BROAD BRUSHED THE POPS A BIT DUE TO THE TIMING AND INTENSITY
PROBLEMS. THE NEXT RATHER MATURE AND DECENTLY STRONG OCCLUDED FRONT
COMES IN AROUND THURSDAY...FOLLOWED BY A SERIES OF RATHER WET FRONTS
LATE NEXT WEEK INTO THE WEEKEND. THE GENERAL TREND NEXT WEEK IS
TOWARD A WETTER MORE ACTIVE PATTERN. AT THIS POINT...OTHER THAN A
COUPLE OF BRIEF DIPS...SNOW LEVELS REMAIN RATHER HIGH AND THESE
SYSTEMS WILL NOT LIKELY ADD MUCH IF ANYTHING TO THE DEFICIENT SNOW
PACK IN THE CASCADES. TOLLESON
&&

.AVIATION...FOG HAS DEVELOPED NORTH OF KKLS AND WILL CONTINUE TO
SPREAD SOUTH OVERNIGHT. WITH LIGHT WINDS AND A MOIST LOWER
ATMOSPHERE FORECASTED FOR THE INTERIOR VALLEY...EXPECT TO SEE
WIDESPREAD FOG AND LOW STRATUS REDEVELOP AND PERSIST THROUGH
SATURDAY MORNING. PERIODS OF IFR TO LIFR CIGS AND VIS ARE POSSIBLE
LATE TONIGHT THROUGH SATURDAY MORNING. VFR CONDITIONS EXPECTED TO
RETURN BY SATURDAY AFTERNOON FOR THE INTERIOR VALLEY. THE
EXCEPTION WILL CONTINUE TO BE KTTD...WHICH WILL SEE VFR CONDITIONS
UNDER EASTERLY WINDS THROUGH SATURDAY EVENING. LIGHT OFFSHORE
FLOW ALONG THE COAST COULD ALSO BRING A MIXTURE OF LIFR TO MVFR
CIGS AND VIS EARLY SATURDAY MORNING WITH CONDITIONS BECOMING VFR
IN THE AFTERNOON.

KPDX AND APPROACHES...VFR CONDITIONS WILL GIVE WAY TO IFR CIGS AND
VIS LATE TONIGHT. EXPECT FOG AND LOW STRATUS TO RETURN BETWEEN
07-10Z SATURDAY AND PERSIST THROUGH AROUND 19Z SATURDAY. BRIEF
PERIODS OF LIFR CIGS AND VIS ARE POSSIBLE EARLY SATURDAY MORNING.
VFR CONDITIONS RETURN SATURDAY AFTERNOON AS EAST WINDS BEGIN TO
INCREASE AT THE TERMINAL. /64

&&

.MARINE...OTHER THAN A BRIEF PERIOD OF ISOLATED SMALL CRAFT
ADVISORY GUSTS...THINGS CONTINUE TO PROGRESS AS PLANNED. AS
SUCH...NO CHANGES WERE MADE WITH THE EVENING UPDATE. HIGH PRES
WILL REMAIN OVER THE REGION THROUGH SAT. SEAS WILL CONTINUE TO BE
AROUND 5 TO 6 FT WITH WIND GUSTS TO 20 KT POSSIBLE. /64

PREVIOUS DISCUSSION FOLLOWS...WILL SEE PATTERN CHANGE NEXT
WEEK...AS A SERIES OF FRONTS PUSH INTO THE REGION. EACH WILL BE
PROGRESSIVELY STRONGER...WITH WINDS 20 TO 25 KT AT TIMES LATER SUN
AND SUN NIGHT...WITH GUSTS 30 TO 35 KT LIKELY ON MON AS NEXT FRONT
PUSHES INTO THE REGION. IF PATTERN HOLDS...GOOD CHANCE OF
SOUTHERLY GALES NEXT THU AND FRI...WITH SEAS BUILDING INTO THE
MID AND UPPER TEENS. ROCKEY.

&&

.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.



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