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

Western Washington


168 
FXUS66 KSEW 161652
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
855 AM PST Fri Nov 16 2018

.SYNOPSIS...Drying and clearing from the north today as a weak 
weather system exits to the southeast today. Saturday through 
Tuesday will be dry, with patchy night and morning fog and cool 
overnight temperatures. A weather system will bring wet weather back 
by mid to late next week.

&&

.SHORT TERM...Light rain showers have tapered off this 
morning with a few lingering showers mainly over the central and 
south Washington coast. Conditions will continue to dry through the 
morning with clearing from the north this afternoon and tonight. 
Highs today will be in the low to mid 50s.

Clearing tonight will help low temperatures dip into the 30s, with 
near freezing temperatures in the far north. Patchy morning fog with 
some freezing fog Saturday will burn off to sunny skies and 
temperatures in the low 50s. Morning fog will return again Sunday 
with clearing and slightly warmer high temperatures,  especially 
through the eastern interior lowlands. Clear skies Sunday night will 
help lows dip again into the 30s near marine and urban areas, and 
into the 20s in outlying areas.

.LONG TERM...from previous discussion...A sharp upper level ridge 
will continue to influence our weather Monday and Tuesday, keeping 
conditions dry. Monday will be mostly sunny while a weak weather 
system tries and fails to make much headway against the ridge. There 
is a chance of rain in the offshore waters. On Tuesday, clouds will 
increase across Washington, and the chance of rain will spread to 
the coast. Highs both days will remain in the low to mid 50s.

The GFS and Euro are now in rough agreement that a weather system 
will impact the area on Wednesday, and conditions will remain 
relatively wet on Thursday. Have increased pops to likely or better 
both Wednesday and Thursday. Highs will be in the low 50s. Burke

&&

.AVIATION...Low clouds, along with spotty light rain showers, 
and reduced visibility are observed across the area this morning. 
Most terminals are IFR or lower at this point with some visby at 
1/4sm or less in spots. A mid level trough axis is diving south 
across the area and will exit throughout the day as a high pressure 
from the Pacific builds in. This will gradually bring improvement, 
but this morning should feature several more hours of reduced 
ceilings and visibility before improvement 18-21Z. 

Clear skies tonight may lead to localized areas of fog. Winds will 
remain southerly ahead of the front, with a northerly component to 
the winds in its wake. Wind speeds will generally be 5-10 knots.

KSEA...Winds have shifted northerly 6-8kts and will remain there 
through the day. Occasional visibility less than 1 mile and ceilings 
at 200 ft or less have been observed this morning and the 
possibility for these bad conditions will prevail through about 18Z 
or so before slow clearing and improvement brings conditions to 
better than IFR. Skies will clear after 21Z and there may be some 
patchy fog late overnight tonight into early Saturday morning. 
Johnson

&&

.MARINE...A trough of low pressure will exit through the area today 
and give way to a ridge of high pressure building east from over the 
Pacific. This will produce some Small Craft Advisory level winds 
through early Saturday morning before improving conditions as the 
ridge of high pressure takes over. Strongest winds today should 
remain in the northern inland waters and then expanding through the 
Strait and northern offshore waters tonight.  Johnson

&&

&&

HYDROLOGY...Models are indicating a rainy period to start up midweek 
through the end of next week. This would drive rivers up sharply. 
But so far, no river flooding looks likely through the next seven 
days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 7 PM this evening to 4 AM PST Saturday 
     for Central U.S. Waters Strait Of Juan De Fuca-Coastal 
     Waters From Cape Flattery To James Island 10 To 60 Nm-
     Coastal Waters From Cape Flattery To James Island Out 10 Nm-
     Coastal Waters From James Island To Point Grenville 10 To 
     60 Nm-Coastal Waters From James Island To Point Grenville 
     Out 10 Nm-East Entrance U.S. Waters Strait Of Juan De Fuca-
     West Entrance U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 4 AM PST early this morning for 
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance 
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 7 AM this morning to 4 AM PST Saturday 
     for Northern Inland Waters Including The San Juan Islands.

&&

$$

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


540 
FXUS66 KPQR 161711 AAA
AFDPQR

Area Forecast Discussion...Updated
National Weather Service Portland OR 
910 AM PST Fri Nov 16 2018

Updated Short Term/Aviation/Marine

.SYNOPSIS...A weak disturbance will move over east Washington today
for a slight chance of rain across southwest Washington. High
pressure strengthens tonight through the weekend. Offshore flow
develops tonight and will intensify Saturday. This will result in
very windy conditions for the west end of the Columbia River Gorge.
The offshore pattern continues into early next week, but will be more
confined to the Gorge. The next chance of precipitation is expected
to return to the area Tuesday night or Wednesday. 

&&

.SHORT TERM...Updated...Today through Sunday...Minimal changes to the
short term. Morning Water vapor imagery shows a sharp upper level
ridge centered from near 55N 140W to 35N 130W. A couple of
short-waves within northwest to north flow aloft were noted on teh
back side of the ridge. The first was moving across NE Washington and
the second was sliding through north and central British Columbia.
GOES 16 and 17 imagery indicate considerable stratus and fog
throughout the Willamette Valley, especially south of KSLE. Earlier
NOWCAST covers this well. At 1630Z KRTX and KLGX dual-pol doppler
radars indicated some light returns across the SW Washington coast
and coastal valleys. KKLS was reporting -RA. Higher resolution
models, such as the Hi-RES ARW and NSSL suggest isolated showers or
very spotty light rain across SW Washington and the North Oregon
coast through the morning. North surface gradients develop in the
afternon as surface high pressure strengthens ovr the NE Pacific. 

Air quality readings this morning were generally good to moderate, an
improvement from 24 hours ago. The afternoon north low-level flow
should help to maintain decent air quality. Also, northwest to north
mid-level wind flow will not be conducive for California smoke to
advect into the area.  

Offshore low-level gradients develop this evening and strengthen
overnight through Saturday as the upper ridge axis moves toward the
coast. The KTTD-KDLS gradient is expected to be around -9 mb Saturday
afternoon. Initially, the offshore flow will have some degree of
impact across a larger area, since it will be more synoptic-scale in
nature. Thus, would expect fairly good air quality conditions
Saturday. Cold air damming on the east side of the Cascades Saturday
night through Sunday will result in more of a gap
wind flow through the Gorge. Expected max gusts should be on the
order of 65-75 mph for most exposed areas such as Crown Point, 50-60
mph at Corbett and 35-45 mph for KTTD. This event does not look as
strong as the previous one and not anticipating the need for a wind
advisory at this time. Weishaar

.LONG TERM...No Changes. Previous discussion follows...Monday night
through Thursday...A dry start to next week is expected with the
strong upper level ridge remaining in place over the Pacific
Northwest. East winds will become increasingly confined to the
eastern Columbia River Gorge. Elsewhere, winds will begin to become
lighter under the strengthening inversion. This pattern will remain
in place until around midweek. Forecast models continue to not be in
great agreement with respect to the timing of the next frontal system
approaching. Continued to utilize an ensemble based approach today,
resulting in highest rain chances holding off until around 
Thanksgiving. However, due to the aforementioned spread in models, 
confidence in the holiday forecast remains lower than normal. Cullen
&&

.AVIATION...Flight conditions vary across the area. In general,
MVFR cigs are in place KSLE northward, with a few patches of IFR
and -DZ embedded within. Further south, locally dense valley fog
is resulting in IFR/LIFR for inland terminals while the 
surrounding area is VFR. Weak frontal system will likely cause 
MVFR to persist for most of today north of KSLE. Willamette 
Valley terminals south of KSLE will continue to see IFR/LIFR this
morning, only gradually improvement into MVFR or possibly VFR as
fog lifts and/or clears mid to late afternoon.

PDX AND APPROACHES...Weak frontal system is bringing IFR/low MVFR
cigs this morning, and may cause a little -DZ at times until 21z.
Expect slow improvement to higher MVFR cigs later this 
afternoon, possibly breaking into VFR by 00z. Some patchy fog may
redevelop this evening before east winds ramp up Sat morning.
Weagle

&&

.MARINE...Seas are slowly coming down after their peak and are
now near around 8 ft at 13 seconds. Seas will settle around 7 ft
today and near 5 ft by the end of the weekend. 

A ridge of high pressure will lay over the waters through today,
then high pressure will strengthen inland for increasing N-NE 
flow through the weekend. Some localized gusts 25-30 kt will be 
possible in the offshore flow over the weekend, mainly below gaps
in the coastal terrain. /mh Weagle

&&

.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
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


071 
FXUS66 KPDT 161710 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
910 AM PST Fri Nov 16 2018

Updated Aviation Discussion

.SHORT TERM...Weak cold front moving slowly south across the
region today. Fairly solid area of clouds with the boundary
however precipitation is light. Mainly some light rain over the
Cascades and Blues. The front will move into central Oregon later
today with increasing clouds and rain showers over the mountains.
High pressure ridge then builds in Sat through early next week
with dry weather. Main concern will be freezing fog and low clouds
developing in the Columbia basin and adjacent valleys. 94

&&

.AVIATION...18Z TAFs...A slow moving cold front will continue to 
sink south through the Oregon terminals this afternoon with VFR 
ceilings 040-060. Some light rain showers will be possible through 
noon or so near PDT/ALW with upslope enhancement into the Blues. 
Skies clear out this evening with high pressure settling back into 
the region. Winds remain light, less than 10KTs. Peck

&&

.PREV DISCUSSION... /issued 233 AM PST Fri Nov 16 2018/ 

SHORT TERM...Today through Sunday night...A weak weather 
disturbance will move southeast today in a northwest flow aloft. 
This system has limited amounts of moisture with it, but there 
should be some light rain and high elevation (above pass level) snow 
over the Northern Blue Mountains and the Wallowa Mountains today, 
especially this morning. This system will gradually move out of the 
area tonight with high pressure aloft building in behind it for the 
remainder of the short term forecast period. As the ridge builds 
into the region there will be an increase in subsidence and 
strengthening of inversions in the lower valleys again. This will 
result in increasing patchy fog and low clouds which will become 
more widespread with time. Temperatures in the valleys will be below 
freezing, especially at night so there will be some freezing fog. 
The fog droplets will freeze to surfaces making them slick. Diurnal 
temperature changes under the areas of low clouds and fog will be 
little, but in the mountains at elevations above the inversions the 
diurnal temperature changes will be much greater. Overall highs will 
be mainly in the 40s to near 50 in these areas, but temperatures 
will have a tough time rising above the 30s in the valleys that are 
under the inversions. Winds will be light through the short term 
period. An air stagnation advisory remains in effect this morning 
for the Yakima Valley due to poor mixing out of pollutants in the 
lower valleys. This may be extended, and possibly expanded, this 
morning per coordination with local air quality officials. 88

LONG TERM...Monday through Friday...Long term period begins with 
good model agreement between operational and ensemble guidance with 
persistent upper level ridging over the Pacific NW continuing 
through at least Tuesday and likely into Wednesday. While dry 
weather and light winds expected, low stratus/fog/freezing fog is 
expected to continue in the Lower Columbia Basin and other 
valleys/basins due to the strengthening low level inversion and air 
stagnation. Like early this past week, diurnal temperature ranges in 
foggy areas, especially the Columbia Basin, will see spreads 
generally less than 10 degrees with highs likely only in the 30s. 
Areas outside the fog - central Oregon and mountains will see much 
larger diurnal temp swings and highs in the 40s to lower 50s. By 
late next week beginning to see the breakdown of and eastward shift 
of the ridge as a series of short waves is expected to bring a good 
chance of rain and mountain snow to the Pacific NW. Models coming 
into better agreement with the approach of the first quick-moving 
open shortwave and cold front pushing through around Wednesday night 
into Thanksgiving. Best chances for precip would be in the mountains 
as the Basin looks to remain fairly shadowed under the westerly 
flow. The arrival of the next system won't be far behind on Friday. 
This system looks to have a better plume of Pacific moisture and 
better upper-level dynamics and could bring a good chance of 
rain/mountain snow for the region, but location and timing are 
inconsistent between the models this far out. Snow levels will hover 
around 3800 to 5000 feet range for the period, so little snow 
impacts for the major corridors. Expect an uptick in winds beginning 
Wednesday ahead of the first wave which will likely help clear up 
some of the persistent stratus and fog. Thursday into Friday will 
likely be windier and any remaining fog and stratus will be 
extinguished. The active pattern is expected to continue into the 
weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  47  30  39  25 /  20  10   0   0 
ALW  48  29  40  27 /  20  10   0   0 
PSC  48  26  43  22 /  10   0   0   0 
YKM  49  26  44  21 /  10  10   0   0 
HRI  49  28  42  24 /  10  10   0   0 
ELN  51  26  45  22 /  10  10   0   0 
RDM  55  28  44  17 /   0  10  10   0 
LGD  50  29  43  24 /  30  20   0   0 
GCD  52  30  47  25 /  10  10   0   0 
DLS  55  31  47  28 /  10  10   0   0 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Air Stagnation Advisory until 1 PM PST this afternoon for WAZ027.

&&

$$

94/74

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

Northeastern Washington and Northern Idaho


391 
FXUS66 KOTX 161147
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
347 AM PST Fri Nov 16 2018

.SYNOPSIS...
A cold front will drop through the region this morning and result
in a chance of rain and mountain snow showers this morning, with
drying from the north this afternoon. Temperatures will be cooler
today with locally breezy winds through north-south valleys. 
The cool and dry weather will persist through the weekend into 
early next week. The weather pattern may become more active as 
Thanksgiving approaches. 



&&

.DISCUSSION...
Today and this evening...An upper level trough will swing through
the forecast area today. Most of the moisture and precipitation 
has been with the warm front and that is currently moving south 
through the southern zones and should be out of the area by
sunrise. The cold front will follow this morning and will open 
the door for scattered rain and snow showers through the morning, 
and mainly in the up-sloping favored areas, but also expect a few
showers moving off the northern mountains through the early 
morning hours. Drier air will move into the region this afternoon 
behind the front and this will bring a drying trend to the area. 
So, for today expect showers across the Cascades this morning 
decreasing rapidly this afternoon. Showers will be a little slower
to dissipate across the Idaho Panhandle. Expect widespread 
showers this morning, showers will continue from I-90 south to the
Camas Prairie and the Blue mountains through sunset with gradual 
dissipation from north to south through the afternoon. Snow 
accumulations will be mainly above 3500-4000 with additional 
accumulations 1-3 inches possible. There may be some isolated 
pockets of freezing rain for the Cascade valleys and the Okanogan 
valley through sunrise. Accumulations will be light, by the 
morning commute could be tricky in places. Temperatures will be 
down 2-4 degrees over Thursday with highs only in the 40s. Winds 
will be out of the north-northeast. These winds will get channeled
down the Okanogan valley and the Purcell Trench with gust 15-25 
mph. The northerly winds will spill out onto the Waterville 
Plateau and the Idaho Palouse as well with gusts 15-20 mph at 
times. 

Tonight through Saturday night...High pressure will creep into the
region tonight with the ridge axis between the coast and the
Cascades through Sunday. This will put the area in a dry and cool
northerly flow. Temperatures will continue to cool off a couple of
degrees each day. Winds will be light out of the northeast. The
forecast challenge then will be how much fog and stratus that will
form tonight and saturday night. Typically fog and stratus is 
likely after light precipitation and building high pressure, 
however, very dry air will move into the region through the day 
and will likely mitigate any widespread fog/stratus tonight. 
Saturday night there will be a better chance for fog and stratus, 
especially for the northern valleys and the lower Columbia basin. 
Tobin 


Sunday through Thursday: Dry conditions continue early this week,
with some fog potential, before a precipitation threat develops 
mid-week on. Through Tuesday the area remains under a ridge of 
high pressure. Some middle to upper level clouds spill across the 
region Sunday and then again toward Tuesday. Otherwise the first 
part of the week will feature limited mixing, light winds and no 
precipitation. However this will bring the threat of some late 
night/morning fog and some air stagnation. Depending on how 
persistent low clouds and fog are, temperatures may be held back 
more than the current forecast. I attempted to show that potential
in the forecast. 

Tuesday night to Thursday the ridge axis shifts east and a 
trough moves onshore. Timing differences persist, with some model
solutions quicker to bring precipitation chances back in than 
others. Most, however, keep the main threat in the Cascades 
through Wednesday before expanding chances east Wednesday night 
and Thursday. There is reasonable consistency/agreement to have 
some high chance to low-end likely PoPs by late Wednesday into 
Thursday near the Cascades crest. Some modest chances will also 
be found toward Idaho by Thursday too. Thus some snow is possible 
over the passes, which may impact Thanksgiving travel. What is 
less certain is how much may fall, if any, as there is wider 
disagreement in this respect. If there is a higher threat of
impacts it appears it would be for the Cascades passes. Some 
solutions have only a couple inches (the most recent EC) and 
others have several more inches (the most recent GFS). So stay 
tuned. Overnight/morning temperatures would support the potential 
for a rain/snow mix in some of the valleys and higher benches too,
but at this time precipitation here looks light. Model so suggest
some increase in winds going into the end of the week, so this
should help stir things up enough to trend temperatures upward
slightly by then. /Cote'

&&

.AVIATION...
12Z TAFs: The stratiform precipitation has moved out of the area
and the radar this morning is showing isolated to scattered
showers moving through the eastern portion of the forecast area.
Showers will continue through mid-morning then should be focused
over the Panhandle mountains south to the Blue mountains. 
Mountain obscurations should be expected. Otherwise much drier 
air is moving into the region as the flow turns northerly and 
this will bring an end to showers for all of the TAF sites between
15z-18z. The northerly winds are piling up the boundary layer 
moisture for KMWH/KEAT and expect MVFR vsby through 15-16z before 
the drier air dissipates the fog. VFR conditons at all TAF site
before 18z. The drier air previously mentioned will inhibit 
fog/stratus formation tonight. There may be some fog at KSFF
overnight but confidence is low. Northerly winds will have the
tendency to push any remaining boundary layer moisture up against 
the Cascades and would effect KEAT. Guidance keeps KEAT VFR, but 
this will need to be monitored the next 24 hours. Tobin



&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        42  24  38  22  39  25 /   0   0   0   0   0   0 
Coeur d'Alene  44  25  39  23  43  26 /  10   0   0   0   0   0 
Pullman        45  25  42  24  44  27 /  30   0   0   0   0   0 
Lewiston       49  30  46  27  48  29 /  40  10   0   0   0   0 
Colville       43  27  40  22  39  25 /   0   0   0   0   0   0 
Sandpoint      42  27  38  22  40  25 /  10   0   0   0   0   0 
Kellogg        41  25  38  25  42  27 /  60   0   0   0   0   0 
Moses Lake     49  24  43  19  41  21 /   0   0   0   0   0   0 
Wenatchee      46  29  42  23  39  26 /  20   0   0   0   0   0 
Omak           45  25  42  22  41  24 /  10   0   0   0   0   0 

&&

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

&&

$$

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