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

Western Washington


857 
FXUS66 KSEW 241548
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
848 AM PDT Sun Sep 24 2017

.SYNOPSIS...High pressure aloft will produce a dry mild day 
today with clouds gradually increasing in advance of an incoming 
weakening weather system. This system is expected to bring a chance 
of rain tonight and Monday. Higher pressure aloft is expected to 
build off the coast Tuesday and move onshore mid week for a period 
of sunshine and above average late September temperatures.

&&

.SHORT TERM...There will be a mix of clouds over the area today 
but also sunshine at times in advance of an approaching weather 
system. The aforementioned frontal system will bring a rain threat
to the area later tonight through Monday evening. The best chance
for rain will be at the coast where rain will be likely Monday. 
Chances will be lower inland as the front falls apart. Highs today
will be near normal and then a few degrees cooler Monday with 
additional cloudiness. An upper ridge will build over the area 
Monday night and Tuesday. Any lingering showers should end Monday 
evening and clouds should decrease over the area Tuesday. Highs 
will return to near normal Tuesday. Schneider

.LONG TERM...Previous discussion...The ridge remains in control 
over W WA Wed and Thu...allowing for dry and warm conditions to 
persist. Temperatures will push into the mid 70s Wed...and a shift
to offshore flow thanks to a developing thermal pressure trough 
will push the temps Thu into the upper 70s and possibly a few 
locations seeing 80. While climatologically this is uncommon...it 
would seem this summer is not done with the area just yet. 

The ridge shifts eastward Friday and an incoming upper level trough 
will serve to cool things down after the brief summer flashback. 
However...models agree that any precip associated with this system 
really breaks down by the time it arrives allowing for slight chance 
POPs at best. SMR

&&

.AVIATION...An upper level ridge will remain over the region for
contd nly flow aloft today. The low level flow will be light
onshore. Local LIFR CIGs/VSBYs will dissipate by 1900 UTC.

KSEA...VFR. Winds will generally be light and variable.

&&

.MARINE...Previous discussion...High pressure over the NE Pacific
will maintain light onshore flow today. A warm front will clip 
the area on Monday with possible Small Craft Advisory winds over 
the Coastal Waters. The flow will turn offshore by midweek as a 
thermal trough forms along the coast. 33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$

www.weather.gov/seattle

You can see an illustrated version of this discussion 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


820 
FXUS66 KPQR 241553
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR 
853 AM PDT Sun Sep 24 2017

.SYNOPSIS...Morning low clouds will give way to passing high clouds 
this afternoon. A weak front arrives Monday, with light rain 
brushing southwest Washington and far northwest Oregon. High 
pressure builds later Tuesday and remains over the region through 
end of next week. Temperatures will peak in the mid 80s under 
offshore flow.
&&

.SHORT TERM...Today through Tuesday...Made some minor changes to 
cloud cover this morning with patchy stratus around the north 
interior. Also, stratus was more patchy in nature along the coast so 
have decreased clouds there. Low clouds will diminish through the 
morning leaving passing high clouds for the remainder of the day. 
remainder of the previous discussion follows. /JBonk

The mid/high clouds offshore will gradually increase over the region
tonight into Mon am as a weak front approaches. Weak front well to
the northwest today will push into the region later Mon and Mon
evening. But, not a lot of moisture with the front. Models in fair
agreement, so will not vary trends much away. Will keep increasing
chance of rain along the coast on Mon, and into the interior late in
the day into the evening. But again, with spotty precipitation with
the front, rainfall amounts will be light and sporadic. Still think
best threat of rain will be to the north, and much less threat as
move south towards Lane county. 

Upper ridge will build over the region on Tue, with decreasing
clouds. Will see somewhat warmer temperatures, thanks to increasing
light offshore flow.					Rockey. 

.LONG TERM...previous discussion. Upper ridge slowly pushes inland 
Wed and Thu, moving east towards the northern Rockies Fri. Low level 
flow remains offshore Wed through Fri as the inverted surface trough 
drifts offshore and weakens. This will bring warmer than normal 
temps to the region including the coast, with the warmest days 
likely to be Wed and Thu. By Fri night models in general agreement 
with pushing a weak shortwave through the Pacific NW, pushing down 
upper heights and allowing a weak cold front to move in. While still 
likely too dry to carry any sort of mentionable pop, the flattened 
flow should still allow some clouds back in, while cooling temps 
down a few degrees. 
&&

.AVIATION...Some IFR conditions around the Columbia River this
morning, but everywhere else is generally VFR. All terminals
should improve to VFR by 18Z.

KPDX AND APPROACHES...VFR conditions through today. Small chance
for MVFR CIG after 12Z Monday. Bowen

&&

.MARINE...Quiet marine weather continues through today and into 
next week with light winds less than 15 knots and seas less than
6 feet. However, the dominant wave period this morning is being
reported at most of the buoys as 7 seconds, which makes the seas
a bit choppy.

North winds will start to increase late in the day on Tuesday as
the thermal tough builds up the coast. Small craft strength 
winds are likely and will begin in the southern waters before 
expanding northward. These gusty winds will likely be short lived
as the gradient relaxes and winds switch to offshore by late in 
the day Wednesday. Bowen/Bentley

&&

.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. This area is

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

Southeastern Washington and Northeastern Oregon


798 
FXUS66 KPDT 242106
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
206 PM PDT Sun Sep 24 2017

.SHORT TERM...Tonight through Wednesday. Upper ridge over the 
area today although high level clouds are starting to increase 
ahead of the next offshore system. This system will move through 
overnight and Monday with mostly cloudy skies. Much of the 
cloudiness will be mid and high level. Any precipitation will be 
confined to just light rain showers over the Cascades. By Tuesday 
the upper ridge will strengthen over the Pacific northwest and 
remain in place through Wednesday. This will bring clear to partly
cloudy skies and warmer temperatures. High temps Monday in the 
60s to lower 70s then warming into the 70s to near 80 Tue/Wed. 
Winds will remain fairly light through the period mostly in the 
5-10 mph range. 94

.LONG TERM...Wednesday night through Sunday...An upper level 
ridge will move over eastern WA and OR Wednesday night. Strong 
radiational cooling will occur Wednesday night under clear skies and 
light winds...especially in mountain valleys including Seneca 
Meacham and Ukiah. As the ridge axis moves east of the CWA Thursday 
night or Friday southwest flow aloft will bring increasing moisture 
to eastern WA and OR. A weak front will move through Canada Friday 
night. Since the dynamic lift will remain in Canada the main effects 
will be increased cloud cover and a slight chance for rain showers 
along the East Slopes of the Washington Cascades. Both the GFS and 
ECMWF 12Z models rebuild the upper level ridge behind the 
front...but previous runs have varied solutions and GFS ensembles 
have a mixture of troughs...ridges...and zonal flow. This 
variability provides low confidence in any solution so I based 
forecast for Saturday and Sunday on a more zonal pattern from 
SuperBlend and CONSALL models rather than operational models. 
Coonfield

&&

.AVIATION...00z TAFS...VFR conditions will prevail through the 
period. There will be intermittent mid and high level clouds moving 
across the region from north to south over the next 24 hours. These 
will be mainly above 8K FT AGL. Winds will remain generally under 12 
kts through the period. 76

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  43  70  48  73 /   0  10  10   0 
ALW  47  71  51  74 /   0  10  10   0 
PSC  46  72  50  77 /   0  10  10   0 
YKM  46  71  48  76 /   0  10  10   0 
HRI  45  72  50  78 /   0  10  10   0 
ELN  45  69  46  75 /   0  10  10   0 
RDM  37  69  41  73 /   0  10  10   0 
LGD  37  66  42  70 /   0  10  10   0 
GCD  36  66  40  73 /   0  10  10   0 
DLS  49  73  52  79 /   0  10  10   0 

&&

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

$$

94/76/76

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

Northeastern Washington and Northern Idaho


194 
FXUS66 KOTX 242108
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
208 PM PDT Sun Sep 24 2017

.SYNOPSIS...
Fall coolness and considerable cloudiness will be across the 
Inland Northwest into Monday. Light showers or sprinkles will 
possible with temperatures in the 60s. The weather will warm up 
and dry out Tuesday through the end of the week. Look for 
temperatures topping out in the upper 70s and lower 80s Thursday 
and Friday. More seasonal and showery weather can be expected for
the upcoming weekend. 

&&

.DISCUSSION...
Tonight through Tuesday: Northerly flow aloft will continue into
early next week as bands of moisture brush through the regions.
Each band is associated with a weak warm air front aloft and
leading to light showers or sprinkles from the mid level cloud
deck with its passage. One of features will graze along the
Canadian border late tonight and overnight, weakening as it moves
east. Could see some isolated mountain showers overnight, but not
much measureable precipitation. A second but strong warm front
will arrive Monday into Monday evening with a slightly better
chance of showers across the mountains and mere sprinkles across
the low lands. Overnight lows will moderate tonight, although the
increase in clouds and added moisture for Monday looks to limit
the warming at the surface. It's not until Tuesday that less cloud
cover and the building ridge will yield to warming temperatures.
As temperatures stay below normal, winds will remain light through
the start of the new week. /rfox. 

Tuesday night through Sunday: An upper ridge builds Wednesday and
Thursday. This will result in mostly clear skies and a warming
trend with 850mb temperatures warming to 13-15C Wednesday and 15-17C
Thursday. This should translate to valley highs climbing well into
the 70s with the warmest spots in the lower 80s. The ridge
flattens Friday through the weekend which should bring a gradual
cool down as west to northwest flow develops with mid level clouds
spilling into the area. Not much moisture showing up through this
period as the jet axis remains primarily north of the area into
British Columbia. Although there may be just enough moisture/lift
to squeeze out light showers at times over the Cascade crest, 
northern mountains, and Idaho Panhandle. JW

&&

.AVIATION...
18Z TAFS: Mid level cloud band with sprinkles will be exiting
KPUW-KLWS by midday. Meanwhile next band of mid clouds moving
south from BC and looks to blanket the region this afternoon.
Within the clearing area, patchy fog has lifted and cumulus is
forming on the ridges especially over northeast WA and north
Idaho. Anticipate varying mid and high overcasts this afternoon
and overnight as weak warm advection continues. Winds will remain
light through the period and cloud bases VFR. Light showers or
sprinkles can be expected, mainly in the mountains this afternoon
and overnight. /rfox. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        46  66  47  69  49  74 /  10  10  10   0   0   0 
Coeur d'Alene  45  64  45  69  45  74 /  10  10  10  10   0   0 
Pullman        43  65  46  69  45  73 /   0  10  10  10   0   0 
Lewiston       48  69  50  73  50  76 /   0  10  10   0   0   0 
Colville       45  69  44  74  45  78 /  10  20  10   0   0   0 
Sandpoint      43  62  42  67  42  72 /  10  20  20  10   0   0 
Kellogg        41  61  42  65  44  71 /  10  10  20  10   0   0 
Moses Lake     47  72  47  76  48  79 /   0  10  10   0   0   0 
Wenatchee      52  71  52  76  53  79 /  10  10  10   0   0   0 
Omak           49  71  48  77  48  80 /  10  10  10   0   0   0 

&&

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

&&

$$

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