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

Western Washington


344 
FXUS66 KSEW 280319
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
820 PM PDT Tue Jun 27 2017

.SYNOPSIS...A surface ridge offshore will maintain onshore flow 
across Western Washington into early next week. This will produce 
typical early summer weather with mild temperatures and morning low 
clouds and afternoon sunshine. An upper level ridge will weaken the 
onshore flow and produce a minor warming trend Thursday and Friday. 
Stronger onshore flow will bring a bit more cloud cover this 
weekend. A weak front could bring a few showers to mainly the coast 
on Sunday.

&&

.SHORT TERM...Satellite imagery shows mostly clear skies across W WA 
this evening except for low marine stratus that has pushed inland 
along the central WA coast. Onshore pressure gradients are around 
1.5 MB. This will help recharge the already somewhat moist marine 
layer over the interior tonight, so Wednesday morning should start 
off with our familiar low stratus clouds covering most of the 
interior lowlands. Burn-off should occur around midday again 
followed by mostly sunny skies Wednesday afternoon. 

An upper level ridge offshore along 135W this evening will move 
steadily eastward, with the axis reaching the offshore waters on 
Thursday then moving slowly across WA on Friday. The ridge will 
weaken the onshore flow for less morning cloud cover Thursday and 
especially on Friday. More sunshine coupled with warming from the 
ridge will bring a minor warming trend. Inland high temperatures 
should be in the 70s on Thursday and in the mid 70s to lower 80s on 
Friday. Coastal highs will be cooler, 60s on Thursday with some 
lower 70s around on Friday. Kam

.LONG TERM...The upper level ridge will exit over the ID panhandle 
Friday night leaving the way clear for a weak front to approach the 
region this weekend. Onshore flow will increase again Friday night 
which will produce more stratus and a deeper marine layer Saturday 
morning. High temperatures will drop back into the 70s. The weak 
front approaching the coast will slide inland on Sunday. There is a 
slight chance for some spotty showers along the coast and maybe the 
north interior. The marine layer will be pretty deep but this could 
allow some intermittent sunbreaks to occur in the afternoon. 

The onshore flow pattern will continue early next week with a 
surface ridge offshore and moderate W flow aloft over the region. So 
Independence Day will have the familiar morning low clouds with some 
afternoon clearing and mild temperatures. Kam

&&

.AVIATION...Weak upper level trof over the region will cont moving
slowly E, with upper level ridge following in its wake. Contd NW 
flow aloft. The low level flow will remain onshore. Areas of coastal 
marine stratus should spread back inland overnight but Wednesday 
should see a bit less of the stratus and it should burn off a bit 
quicker.

KSEA...Morning low clouds from about 12-18z are a pretty good bet 
again Wednesday morning--although OTH-SEA is only +2mb and yesterday 
at this time it was +4mb, so I may trim it back a bit and it could 
be that a four hour tempo group might be enough to cover it on Wed.

&&

.MARINE...Higher pres offshore with lower pres E of the Cascades 
will maintain onshore flow of varying strength through this weekend. 
The flow will become strong Friday afternoon and evening for the 
possibility of gale force winds over parts of the Strait of Juan de 
Fuca.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisories central/eastern Strait of Juan de Fuca.

&&

$$

www.weather.gov/seattle

An illustrated version of this forecast discussion can be seen at 
www.wrh.noaa.gov/sew/gafd/latest_webafd.html

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

Southwestern Washington and Western Oregon


638 
FXUS66 KPQR 280414
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
914 PM PDT Tue Jun 27 2017

.SYNOPSIS...Dry, onshore flow continues through the forecast period.
An upper ridge will traverse the area Thursday and Friday, bringing 
less morning low clouds and slightly warmer afternoon temperatures.
Otherwise, the seasonable pattern of morning clouds and afternoon sun
continues through the weekend. 

&&

.SHORT TERM...Tonight through Saturday...Forecast appears to be in
good shape, with classic summertime weather expected for the next
week across the Pacific Northwest. Only minor changes were made with
the evening update, mainly to allow for a bit more morning low
cloudiness Wed/Thu mornings. 

An upper ridge near 135W keeps northwest flow over the region through
Wednesday. A weak but dry shortwave in the northwest flow moves over
the area early tomorrow, so expecting another robust marine layer in
the morning. Model soundings suggest a robust marine layer about
3000-4000 ft deep around 12z Wed, which should allow stratus to push
all the way to near the Cascade crest. Coastal areas may see some
spotty drizzle due to the deep onshore flow. Clouds will be slow to
clear, but eventually most of the forecast area should break into a
mostly sunny afternoon with seasonable temps in the 70s inland
valleys and 60s along the coast. 

The upper ridge will move closer to shore later Wednesday and 
Thursday, then traverse western OR/WA Friday morning. While offshore 
flow never develops, the upper ridging should compress the marine
layer to 1500-2000 ft Wed night/Thu morning. This should lead to a
less extensive marine push, with any morning clouds likely quicker to
burn off Thu morning. As a result of this and 850 mb temps warming to
around +14 to +15 deg C, temps should warm up 5-10 degrees
inland...with highs in the lower to mid 80s in the valleys. Even less
stratus is expected Friday morning as the upper ridge axis moves
across the Pac NW. However, flow remains onshore, so temps should be
similar or just slightly warmer Friday. 

Saturday sees the ridge flatten and move eastward, bringing a benign
westerly flow and thickening marine layer, for morning clouds
followed by afternoon sun.  Weagle/DRB

.LONG TERM...Saturday night through Tuesday...Westerly flow continues
through the extended period. A couple of embedded, low amplitude
ridge/trough systems pass mostly to the north of area, with GFS/GEFS
timing favoring weak shortwaves late Saturday and again on Monday.
The main result will be a thickening marine layer over the weekend
and particularly on Monday. Depending on the strength of these
shortwaves, some drizzle/very light precipitation along coastal zones
is not out of the question. That said, the odds favor a dry forecast
with many dry ensemble members through the period. Temperatures 
should be close to seasonal normals this weekend, and near or 
slightly below normal early next week. DRB 

&&

.AVIATION...Cigs may lower to below 1000 feet along the coast 
tonight. A shortwave upper trough moving over the area tonight 
will maintain a deep marine layer and expect coastal MVFR stratus
to move inland into the Willamette Valley and Cascade foothills 
early Wednesday morning (~12z). Inland areas should clear to VFR 
Wednesday afternoon.

KPDX AND APPROACHES...Marine stratus will return MVFR cigs very 
early Wednesday morning (11-13z), and clear to VFR Wednesday 
afternoon. ~Bowen/TJ

&&

.MARINE...A persistent surface pressure pattern with high 
pressure over the NE Pacific and a thermal low in Northern CA 
will result in little changes to the overall marine weather 
through the weekend. N-NW winds will mostly remain below 25 kt, 
although there will be a few gusts around 25 kt in the waters 
beyond 20 nm this evening. The next chance for winds of that
strength will be when surface high pressure increases a tad on 
Sunday and the north winds will likely strengthen to 25 kt, 
especially south of Cascade Head. 

A combination of wind wave and fresh swell will create choppy 
seas with heights 5 to 8 feet and dominant periods around 8 
seconds today and Wednesday. A strong ebb Wednesday morning may 
steepen the seas nearshore (0-5 nm) a few hours around the 845 AM
ebb. A weak low moving across the Gulf of Alaska Wednesday night
and Thursday will increase wave periods to around 10-11 seconds 
beginning early Thursday. ~Bowen/TJ

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for Rough Columbia River Bar from 8 AM to 
     11 AM PDT Wednesday.

&&

$$

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This discussion is for Northwest Oregon and Southwest Washington 
from the Cascade crest to 60 nautical miles offshore. This 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


310 
FXUS66 KPDT 280323
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
823 PM PDT Tue Jun 27 2017

.SHORT TERM...Tonight and Wednesday...Forecast area will be
under a weak cyclonic flow as an upper level low passes through 
western Canada overnight and Wednesday. This will places us under a 
dry northwest flow aloft with mostly clear skies and seasonable 
temperatures. It will also generate some locally breezy winds along 
the east slopes of the Cascades spilling out into the Columbia Basin 
through this evening and again Wednesday afternoon and evening.   


&&

.PREV DISCUSSION... /issued 130 PM PDT Tue Jun 27 2017/ 

SHORT TERM...Upper level flow will shift from west to northwest
tonight as a ridge builds offshore. Winds will be locally breezy
to windy in the Kittitas Valley and Columbia River Gorge Wednesday
as cross Cascade pressure gradients increase gap winds.  The 
upper level ridge will drift toward the coast Wednesday and 
Thursday. Dry northerly flow will keep skies mostly clear with a 
slow warming trend. The ridge will move inland and weaken Friday 
as a short wave dives into MT. This wave will increase sky cover 
Friday in Wallowa County but precipitation is expected to remain 
east of the CWA Friday.  Coonfield

LONG TERM...Friday night through Sunday. Dry westerly flow aloft
over the region this weekend. Skies will be clear to partly cloudy.
Temperatures will be a few degrees above normal with highs in the
80s to lower 90s. Lows in the upper 40s and 50s.  94

Monday through Wednesday morning...Models remain in good agreement
of a continued zonal pattern with seasonable temperature...mostly
clear skies and little chance of precipitation. 74

AVIATION...00Z TAFS...VFR conditions will persist across all 
terminal locations through the next 24 hours. FEW-SCT cumulus will
persist through sunset at most terminals with additional SCT-BKN 
cirrus associated with a weak mid-level wave moving out of the
region by late tonight. 74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  82  54  85 /   0   0   0   0 
ALW  60  84  59  87 /   0   0   0   0 
PSC  58  88  56  90 /   0   0   0   0 
YKM  57  87  56  89 /   0   0   0   0 
HRI  58  85  55  88 /   0   0   0   0 
ELN  56  82  55  86 /   0   0   0   0 
RDM  43  81  41  85 /   0   0   0   0 
LGD  49  78  46  82 /   0   0   0   0 
GCD  47  80  40  84 /   0   0   0   0 
DLS  58  81  58  88 /   0   0   0   0 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

91/91/91

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

Northeastern Washington and Northern Idaho


020 
FXUS66 KOTX 272348
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
448 PM PDT Tue Jun 27 2017

.SYNOPSIS...
A weak weather disturbance will bring the threat of thunderstorms
to the northern mountains on Wednesday. Otherwise, the weather
will be dry and mild through the remained of the week. The weekend
will see continued dry weather but warmer temperatures. The a dry
cool front will bring breezy and milder weather to the region by
the 4th of July.

&&

.DISCUSSION...
Tonight through Thursday: The low that was partly responsible for
yesterday's weather is still up in BC/Alberta. The northerly flow
on the backside of this low will bring the chance of thunderstorms
to form over the northern mountains of Washington and Idaho. The
models are quite disparate on this situation. They also show
surface-based instability, but most don't show any precipitation
being generated. The ECMWF and SREF about the only models with
precipitation. I've decided to put a slight chance of thunder
storms for northeast WA, the Pasayten Wilderness, an the northern
Panhandle. If any storms do develop, the northerly flow has the
potential to carry them off the mountains and in to the Spokane
metro area. At this point I've left the mention of showers/storms
out of the Spokane/CdA forecast, but the night shift may need to
add it.

By Thursday, the offshore ridge will amplify which should push any
shower chances off to the east. This will also begin the start of
the next round of warming temperatures.  RJ

Friday through Tuesday: The ridge that was in the area will begin
to flatten into a zonal flow pattern allowing a weak push of 
moisture along the Canadian border and will bring a chance of some
light precip and possible isolated lightning strike. After a
brief ridge, a trof will move into the region beginning late
Sunday. The model agreement of how deep the trof digs is pretty 
low but is expected to be a drier trof with very little precip
chances. This is expected to bring breezy conditions to the 
Columbia Basin as the gradient tightens across the region. 
Sustained winds in the low teens and gusts into the mid 20s will 
be expected. Temperatures will be near normal with highs in the
upper 70s to 80s and lows in the 50s. /JDC 

&&

.AVIATION...
00Z TAFS: Expect dry weather and mostly clear skies for the next 
24 hours. Winds will pick up through the Cascade gaps with gusts
of 20-25 kts expected at KEAT this evening.  JW

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        56  82  57  84  60  89 /   0   0  10   0   0   0 
Coeur d'Alene  53  78  53  81  55  86 /   0  10  20   0   0   0 
Pullman        51  77  52  80  56  86 /   0   0   0   0   0   0 
Lewiston       58  84  57  87  60  92 /   0   0   0   0   0   0 
Colville       51  82  52  85  54  90 /   0  20  20   0   0   0 
Sandpoint      47  78  47  79  50  83 /   0  30  30  10   0   0 
Kellogg        51  75  51  78  53  83 /  10  20  20  10   0   0 
Moses Lake     54  87  55  89  57  94 /   0   0   0   0   0   0 
Wenatchee      59  84  59  88  62  93 /   0   0   0   0   0   0 
Omak           53  85  54  88  56  92 /   0  10   0   0   0   0 

&&

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

$$

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