[ W WA | SW WA and W OR | SE WA and NE OR | NE WA and N ID ]

Western Washington


390 
FXUS66 KSEW 291136
GPHAFD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
318 AM PDT SUN MAY 29 2016

.SYNOPSIS...SHOWERS WILL GRADUALLY DIMINISH TODAY AS AN
UPPER LEVEL LOW OVER BRITISH COLUMBIA MOVES SLOWLY EAST. A STRONG
UPPER LEVEL RIDGE WILL BUILD OVER THE REGION MONDAY, BRINGING MOSTLY
SUNNY AND WARMER WEATHER FOR MEMORIAL DAY AND CONTINUING THROUGH THE
MIDDLE OF NEXT WEEK.

&&

.SHORT TERM...THE UPPER LEVEL LOW OVER B.C. THAT HAS BEEN
INFLUENCING WEATHER IN W WA THE PAST FEW DAYS (PIC0) DOES NOT SEEM
TO BE IN MUCH OF A HURRY TO GO AND PESTER SOME OTHER GEOGRAPHIC
LOCATION FOR A WHILE...AS MODELS PROG IT TO REMAIN NEARLY STATIONARY
TODAY...ONLY STARTING TO SHUFFLE ON LATE THIS AFTERNOON AND EARLY
EVENING. THIS WILL BE ENOUGH TO KEEP POPS IN FOR POINTS FROM THE
PUGET SOUND EAST...BUT WILL ALSO ALLOW FOR SOME CLEARING ALONG THE
COAST AND EVEN SNEAKING INTO THE NORTH INTERIOR AND SAN JUANS. BY
TONIGHT...THE INFLUENCE OF AN UPPER LEVEL RIDGE (PIC1) WILL START TO
BE FELT ALL OVER THE CWA AS CONDITIONS START TO DRY. SOME OVERNIGHT
CLEARING MIGHT BE POSSIBLE...EMPHASIS ON THE MIGHT...AS LINGERING
LOW LEVEL MOISTURE MAY CANCEL THAT OUT WITH SOME LOW CLOUDS.

THIS UPPER LEVEL HIGH MAKES THE REMAINDER OF THE SHORT TERM
DISCUSSION RATHER EASY...AS CLEAR AND SUNNY SKIES WITH WARMER
TEMPERATURES ARE EXPECTED FOR MUCH OF THE WEEK...AND IT CERTAINLY
DOES NOT WASTE ANY TIME WARMING THINGS UP. HIGHS ON MEMORIAL DAY
LEAP UP TO MID TO UPPER 60S...WITH 70 EXPECTED IN THE SEATTLE METRO
AREA...SO COOKOUT PLANS ARE GO. TUESDAY WILL MAKE A GOOD PUSH FOR 80
WHILE TEMPS WILL PEAK ON WEDNESDAY...WITH HIGHS GENERALLY IN THE
UPPER 70S TO LOW 80S. THE HEATING OF THOSE TWO DAYS LOOKS TO SET UP
A THERMAL PRESSURE TROUGH (PIC2)...TURNING FLOW OFFSHORE AND HELPING
TO RATCHET UP THE HEAT.  SMR

.LONG TERM...THE THERMAL PRESSURE TROUGH MOVES ON BY THE TIME
THURSDAY ROLLS AROUND...ALLOWING FOR ONSHORE FLOW TO RETURN AND
PROVIDING A MORE MODERATING INFLUENCE ON TEMPS. THE RIDGE ALSO LOOKS
TO FLATTEN OUT AROUND THIS TIME...ALLOWING FOR THE EMERGENCE OF POPS
THURSDAY AFTERNOON...MAINLY FOR THE OLYMPIC PENINSULA AND FOR POINTS
FROM MARYSVILLE NORTH. MODELS START TO DISAGREE SOMEWHAT AFTER THIS.
THE ECMWF WANTS TO KEEP POPS IN FOR FRIDAY...WHILE THE GFS DRIES
THINGS OUT QUICKLY AS THE RIDGE REAMPLIFIES. OPTED TO SPLIT THE
DIFFERENCE WITH SLIGHT CHANCE POPS FOR THE LOCATIONS MENTIONED WHEN
DISCUSSING THURSDAY. THE TWO MODELS FLIP POSITIONS FOR THE START OF
NEXT WEEK...WITH GFS PROVING THE WETTER SOLUTION AS IT WANTS TO MOVE
AN UPPER LEVEL TROUGH INTO THE AREA...WHILE THE ECMWF KEEPS W WA
UNDER THE RIDGE. KIND OF LEANED TOWARD THE DRIER SOLUTION AT THIS
TIME...BUT PLENTY OF TIME AND REASON TO CHANGE.  SMR

&&

.AVIATION... AN UPPER LEVEL TROUGH OVER B.C. EXTENDING SOUTH ACROSS
WASHINGTON (PIC10) WILL SHIFT EASTWARD THROUGH TONIGHT. HIGH
PRESSURE ALOFT WILL BUILD OVER THE NORTHEAST PACIFIC. LIGHT
NORTHWESTERLY FLOW ALOFT BECOMING NORTHERLY TONIGHT AND MONDAY
(PIC11) (PIC12). GENERALLY STABLE AND MOIST IN THE LOWER LEVELS. AIR
MASS BECOMING DRIER LATER TONIGHT AND MONDAY WITH NORTHERLY FLOW
DEVELOPING IN THE LOW LEVELS. 

CIGS WILL VARY ACROSS THE AREA TODAY. PREDOMINATE MVFR STRATUS
EXPECTED THIS MORNING WITH ISOLATED POCKETS OF IFR...LIFTING TO
MOSTLY VFR IN THE AFTERNOON. SCATTERED SHOWERS CAN BE EXPECTED
THROUGH THIS EVENING...ESPECIALLY OVER HIGHER TERRAIN AND IN A
POSSIBLE CENTRAL PUGET SOUND CONVERGENCE ZONE WHICH MAY AFFECT THE
KSEA/KBFI/KPAE TERMINALS. A SWITCH FROM SOUTHERLY TO NORTHERLY WIND
IS EXPECTED THIS AFTERNOON IN GREATER PUGET SOUND INCLUDING
KSEA/KBFI.

KSEA...SOUTH TO SOUTHWEST WIND 8-12 KT...BECOMING NORTHERLY 7-10 KT
THIS AFTERNOON...EASING TONIGHT. MAINLY MVFR CIGS THIS MORNING
BEFORE IMPROVING TO MOSTLY VFR STRATUS. A PUGET SOUND CONVERGENCE
ZONE COULD FORM TODAY PRODUCING SHOWERS AS THE WINDS SWITCH FROM
SOUTHERLY TO NORTHERLY THIS AFTERNOON.  

&&

.MARINE...POST-FRONTAL ONSHORE FLOW WILL PREVAIL THROUGH TONIGHT
(PIC13) BUT GRADUALLY EASE. SMALL CRAFT ADVISORY WESTERLY WINDS IN
THE CENTRAL AND EAST STRAIT OF JUAN DE FUCA IS LIKELY THROUGH
TONIGHT. WINDS WILL GENERALLY STAY BELOW 20 KT ALL OTHER WATERS IN
THE NEAR-TERM.

HIGH PRESSURE WILL BUILD OFFSHORE ON MEMORIAL DAY. THIS WILL GIVE
THE POTENTIAL FOR NORTHWESTERLY WINDS UP TO 25 KT OVER PORTIONS OF
THE COASTAL WATERS MONDAY AFTERNOON AND EVENING. WINDS WILL BECOME
NORTHERLY INLAND AND DOMINATE ON TUESDAY AS A THERMALLY INDUCED
TROUGH OF LOW PRESSURE NUDGES NORTHWARD ALONG THE WESTERN OREGON AND
SOUTH WASHINGTON COASTS. THE TROUGH WILL PUSH INLAND WEDNESDAY WITH
A MARINE PUSH LIKELY IN THE EVENING. DTM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY CENTRAL AND EAST STRAIT THROUGH LATE TONIGHT.

&&

$$

WWW.WEATHER.GOV/SEATTLE

[ W WA | SW WA and W OR | SE WA and NE OR | NE WA and N ID ]

Southwestern Washington and Western Oregon


658 
FXUS66 KPQR 290909
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
210 am PDT Sun May 29 2016

.SYNOPSIS...An upper level low pressure system over southern British
Columbia will persist today, bringing onshore flow to southwest
Washington and parts of northwest Oregon. This will keep a small
chance for some precipitation across the northern and coastal parts
of the forecast area. Upper level ridging will start to build Sunday
night, then strengthen Memorial Day and Tuesday, resulting in much
warmer and drier conditions. Daytime temperatures are expected to
cool a bit late in the week. 
&&

.SHORT TERM...(Tonight through Tuesday)...A shortwave trough in
water vapor pictures was off the WA coast early Sun morning near
128w, rotating around the base of the BC upper level trough. Low
level flow was generally onshore across the forecast area, with a
fairly solid area of low clouds banked up against the coast and
coast range, and to a lesser extent the n part of the Cascades.
Surface observations and radar indicated scattered showers were
mainly over western WA and off the WA coast. As the shortwave moves
e across the Pacific NW today, will keep in some low pops for light
rain or drizzle this morning, mainly for areas where clouds had
already filled in. Will also hang on to a slight chance of showers
across the n this afternoon. Pops drop off quickly by evening as the
upper trough pushes off to the east, and ridging aloft begins to
build in from the west. With the trough brushing across and onshore
flow, may see high temps today a couple degrees cooler than Sat.

Mon and Tue models agree on the upper ridge shifting inland over the
Pacific NW. Low level flow turns more northerly, and eventually
offshore for most areas by Tue morning as a thermally induced
surface trough builds n up the Oregon coast. The trough appears
likely to move inland into the Coast Range by Tue afternoon, turning
flow back onshore on the coast. Dry weather and warming temps will
be the result, with inland high temps approaching 90 Tue afternoon
as model h8 temps rise to near 18 deg c. Should still be warm on the
coast Tue morning, before onshore flow brings cooling marine air in
the afternoon. 

.LONG TERM...Tuesday night through Saturday...The upper level ridge
will persist over the Pac NW through Wednesday keeping temps on the
warmer side of things. Models continue to show 850mb temps near 20C.
With the thermal trough shifting inland slightly on Wednesday this
should allow temps in the interior to warm significantly, with
widespread afternoon highs around 90F likely. SW flow aloft through
the end of the week likely to keep the region dry. Although still
warmer than normal through the end of the week under ridging aloft,
onshore flow should provide some moderation in temps late in the
week. 
&&

.AVIATION...Weak front over far northwest Oregon this am is
maintaining onshore flow. Mix of MVFR and VFR along the coast this
am, along with patchy drizzle. These clouds continue to work
inland up the Columbia River and over the Coast Ranges this am.
Still think will see these most inland extent of the MVFR clouds
may reach KPDX/KTTD by 13Z. 

Other area of clouds over the Cascades continue to backbuild, with
that deck around 4000 ft. This deck will gradually break apart
between 18z and 20z, with scattered clouds inland after 21z. 

PDX AND APPROACHES...A 4000 ft cloud deck will remain through 20z,
then break apart and scatter by 22z. While not likely, there is
small chance that will see scattered to broken clouds of 2000 ft
between 12z and 16z.                       TAFcaster...rockey. 
&&

.MARINE...High pressure over the northeast Pacific will build
today and Monday. Meanwhile, thermal low pressure over NW
California will build north along SW Oregon coast. This will
bring typical early summer of gusty north to northwesterly winds,
with the strongest winds to south of Cascade Head. While may see a
few gusts 20 to 25 kt around Florence southward later today. But,
it appears strongest winds will be Mon and Tue
afternoons/evenings, where winds 15 to 25 kt to south of Cascade
Head. To north of Cascade head, may see a few gusts reach 25 kt,
but think will be few and far between. Northerly winds continue
for Wed to Fri, but appears gradients will be weaker, with winds
only 10 to 20 kt.

Seas hovering at 3 to 5 ft trough Monday am, but as winds pick up
so will the short period wind waves. will see seas 5 to 8 ft for
late Mon through Wed, with higher seas south of Cascade Head.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&

$$ 

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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.

[ W WA | SW WA and W OR | SE WA and NE OR | NE WA and N ID ]

Southeastern Washington and Northeastern Oregon


853 
FXUS66 KPDT 291127 AAA
AFDPDT

Area Forecast Discussion...Update
National Weather Service Pendleton OR
425 AM PDT SUN MAY 29 2016

Updated Aviation Discussion

.SHORT TERM...Today through Tuesday...Another upper trough and
vorticity maximum will move across the CWA today...though it is a
weak system. The flow will be from the southwest which will
transport some moisture and instability into the northeast mountain
today. There will also be some moisture from the west spilling over
the crest of the Washington Cascades onto the east slopes. These
areas can expect a chance of afternoon showers and a slight chance
of afternoon thunderstorms. Any thunderstorms that develop will be
mostly weak...though a couple could become strong but not severe.
Showers and thunderstorms will end by late this evening and then a
strong upper ridge will begin to build over the CWA on Monday and
Tuesday. Temperatures will be near normal today and Monday but then
they will quickly warm to above normal on Tuesday. Tuesday will be
the beginning of an extended warm spell with lower elevation highs
Tuesday in the lower to mid 80s. Winds will pickup today becoming
breezy to windy...mainly in the Lower Columbia Basin and adjacent
valleys and Blue Mountain foothills. Winds will diminish by late
this evening and then winds will be light for the remainder of the
short term forecast period. 88

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY...The extended period will
start off with a large upper level ridge firmly in place over the
forecast area Tuesday night and Wednesday AM. As the ridge axis
slides just east a return southerly flow may be just enough to see a
slight chance of an afternoon thunderstorm in Deschutes and Crook
Counties Wednesday PM. Otherwise the remainder of the CWA should
remain dry with warming temperatures (mid-80s to lower 90s). A
trough then moves by well to our north on Weds night and will act to
lower heights as it suppresses the ridge. How much the ridge is
suppressed remains to be seen as our forecast area is caught in the
middle (between the ridge over NV/UT and the advancing trough over
Northern WA / BC). Later Thursday into Thursday night the latest
guidance is in good agreement that yet another upper level ridge
will rebuild over our CWA from the south. There will be a slight
chance of thunderstorms...mainly in the mountains in the developing
southerly flow around this ridge. As heights continue to rise
believe Friday ends up being generally dry and warm for much of the
area. The ridge continues to build over the intermountain west for
Saturday...putting our area on the NW side of it...this means a
slight chance for afternoon/evening thunderstorms yet again as
moisture continues to increase from the south. Saturday will be
downright hot...with highs reaching at least the lower to mid-90s in
the valleys/basins and 80s in the mountains. This is 15-20 degrees
above average for this time of year and could even be close to a
record for some locations. Model uncertainty increases for Sunday as
the latest GFS/CMC bring a trough into the area with increasing
chances for showers and thunderstorms. The increasing clouds would
also mean temperatures lowering at least a few degrees. The latest
ECMWF does not have the well defined trough...but instead only very
slowly moves the upper ridge east...allowing for diurnal
showers/storms to develop. For now took a blend of the latest
available guidance until a viable...clear solution emerges. 77

&&

.AVIATION...12Z TAFS...VFR conditions forecast at all terminals
through the TAF period. A Weak system moving across the region will
bring SCT to BKN clouds between 6k to 12k FT AGL through much of the
day Sunday. Look for a gradual clearing trend at most terminals
after 30/06z.

Winds AOB 12 kts through 29/15z. Then westerly winds quickly
increase to between 15-25 kts region wide during the afternoon and
early evening hours. Winds should gradually decrease after 30/06z
back under 12 kts. 77

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  75  44  75  45 /  10  10   0   0 
ALW  76  48  76  46 /  10  10   0   0 
PSC  79  51  79  49 /  10   0   0   0 
YKM  75  47  79  47 /  10   0   0   0 
HRI  78  49  78  46 /  10   0   0   0 
ELN  67  46  76  47 /  10  10   0   0 
RDM  71  39  74  39 /  10   0   0   0 
LGD  70  44  70  41 /  30  20   0   0 
GCD  72  43  73  41 /  10  10   0   0 
DLS  73  48  80  48 /  10  10   0   0 

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

$$

88/77/77

[ W WA | SW WA and W OR | SE WA and NE OR | NE WA and N ID ]

Northeastern Washington and Northern Idaho


092 
FXUS66 KOTX 291143
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
443 AM PDT SUN MAY 29 2016

.SYNOPSIS...
The rest of the Memorial Day weekend will be locally breezy with a
slow warm up. Scattered showers are expected to impact the Idaho
Panhandle and northeast Washington at times over the holiday
weekend. Sunday's system will also produce wind gusts of 20 to 35
mph during the afternoon and evening along the East Slopes of the
Cascades into the Columbia Basin. Much warmer weather will develop
Tuesday through Wednesday before a brief cooldown in the presence
of isolated showers and thunder Thursday.

&&

.DISCUSSION...
...Breezy to Windy conditions this afternoon and early evening
   across portions of Central and eastern WA...

Today through Monday Night: A weak wave is moving across E WA and
N ID this morning ahead of the main trough. This has produced some
very light rain or sprinkles across the aforementioned areas.
Expect this to be out of the area in the next few hours and the
main trough to move south out of Canada into northeast WA and
north ID. Instability increases in the afternoon for a slight
chance of thunderstorm development stretching from the Blue
Mountains northeast towards Lookout Pass and into north ID and WA
mountains. The main concern today is the afternoon and evening
winds as a pressure gradient sets up along the Cascades. Westerly
winds 15-25 mph with gusts up to 35 mph will be possible across
portions of the Wenatchee Valley, Waterville Plateau and into the
Columbia Basin/Moses Lake area. Slightly lighter winds is expected
further east into the Spokane area and Palouse. The winds will
peak btwn 4 and 8 pm. Clouds will decrease through the night. Some
of the 'typical' cooler valleys could see lows in the upper 30s by
Monday morning. Monday the upper level ridge will begin to build
into the Pac NW. We will see less clouds than we have seen the
last week and temps will finally warm to right around average for
this time of the year...upper 60s to mid 70s for the valleys. Have
some residual showers across extreme NE WA and north ID with
thunder in the afternoon, but otherwise a nice looking day!
/Nisbet

Tuesday through Sunday: Rapidly warming temperatures through the
first half of the week still looks on track as a sharp upper ridge
with significant ht rises strengthens over the region. The 850mb
temps warm 9-15C by Wed... depending on what model guidance is
favored. Concerning this, the GFS has shown a bit more run to run
consistency compared to the ECMWF and ensemble means, backed up by
the Canadian. However, confidence decreases significantly by late
week with the ridge breakdown as all model guidance is having
timing issues with bringing in a weak short- wave trough and
dropping pcpn in the form of isolated showers and thunder across
the Pac Nw. We did not make significant changes to the fcst.
However...there is a decent signal (especially with the GFS) for
elevated nocturnal showers, with isolated thunder not out of the
question, across SE WA and adjacent parts of the Idaho Panhandle
Wed Nt. We have no pcpn in the fcst until the Thurs afternoon
thunder, so this Wed Nt threat will need to be looked at in more
depth. Cloud cover moving into region from the south Wed and Thurs
would certainly influence the current mid 80s to lower 90s we have
in the fcst. These are all issues that will be worked out the next
few days...including potential rises on some streams in the E
slopes of the Cascades.bz

&&

.AVIATION...
12Z TAFS: Light sprinkles possible at KLWS for the next hour.
Otherwise sites will remain dry the rest of the morning. Today
will bring a threat of showers around the mountains and
KGEG/KSFF/KCOE sites in the afternoon. There will also be a
threat of thunderstorms, but the risk will mainly be north and
east of the TAF sites. Winds increase again, especially after
20Z. Gusts near 20-35kts are possible, strongest btwn 23-03Z near
the EAT. The shower threat and winds will then start to abate
after 04Z with skies clearing overnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        68  44  70  45  76  49 /  20   0   0   0   0   0 
Coeur d'Alene  68  44  69  42  74  46 /  20  10  10  10   0   0 
Pullman        68  43  67  41  73  46 /  10   0   0   0   0   0 
Lewiston       75  49  74  47  81  53 /  10   0   0   0   0   0 
Colville       69  44  72  42  81  41 /  30  20  10  10   0   0 
Sandpoint      66  42  67  39  73  43 /  40  20  10  10   0   0 
Kellogg        65  43  64  39  73  44 /  20  20  10  10   0   0 
Moses Lake     75  46  76  44  82  48 /   0   0   0   0   0   0 
Wenatchee      72  49  76  51  81  56 /   0   0   0   0   0   0 
Omak           72  45  75  47  81  50 /  20   0   0   0   0   0 

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$

[ W WA | SW WA and W OR | SE WA and NE OR | NE WA and N ID ]

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