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

Western Washington


585 
FXUS66 KSEW 290447
GPHAFD

Area Forecast Discussion
National Weather Service Seattle WA
929 PM PDT Tue Mar 28 2017

.SYNOPSIS...Another warm front will bring more rain and higher 
mountain snow to the area later tonight through Wednesday morning. 
Low pressure will move into Vancouver Island with the associated 
cold front pushing through Western Washington by midday Wednesday.
An upper trough will follow on Thursday resulting in showers and 
sun breaks. High pressure will build Friday and Friday night 
providing mostly dry weather. Weak fronts may affect the region 
Sunday and early next week. 

&&

.SHORT TERM...Another batch of rain is moving onshore this evening
ahead of a warm front that will move into the area early Wednesday 
morning. The warm front will be quickly followed by a cold front 
(PIC10) associated with a low that is developing well offshore and 
moving toward central or northern Vancouver Island midday Wednesday. 
Precipitation will be heaviest on the western portion of the Olympic 
peninsula (where 2 or 3 inches more can be expected) and in the 
Cascades while ligher amounts are expected in the central portions 
of the Puget Sound area where there will be rain shadowing going on. 
The warm air is taking its time getting into the North Cascades this 
evening and Mt Baker is still getting snowfall at 5000 feet. The 
delay in the warm up is supported by the 00z NAM solutions this 
evening. Based on that, will extend the winter weather advisory into 
late Wednesday morning.

Rain will become showers on Wednesday as low pressure moves into 
Vancouver Island and cooler, somewhat drier air filters into 
Western Washington. Snow levels will drop back down to most pass 
levels and the strong flow give some orographic help in snowfall. 
But the lack of moisture should still keep amounts limited to just
a few inches or less, including the passes. A meso low is still 
expected to develop on the north Kitsap peninsula. Latest models 
are a little stronger that yesterday but the kbli-kpdx gradient 
never reaches +10 mb on most models and the wrf-gfs keeps winds 
generally sub-advisory from late morning to the afternoon. 
Strongest southerly gusts will occur from central/north Puget 
Sound to around Admiralty Inlet, reaching 35 to 40 mph at times. A
westerly push down the Strait may also bring some gusts to the 
land portions of the Strait and west side of Whidbey Island but 
still sub-advisory. With recent rainfall and saturated soil, it 
will not be surprising to see some trees topple in gusts of 35 or 
40 mph.

The weather begins to quiet down Wednesday night and Thursday. An 
upper trough will move across the region bringing showers. A Puget 
Sound convergence zone is also possible, with the best chance of 
this bringing enhanced showers to Snohomish and King counties. 
Showers will taper off Sunday afternoon and most areas will see sun 
breaks. 

High pressure aloft builds Thursday night and Friday giving a period 
of dry weather. The low level flow will be light and 500 mb heights 
over 5700m will support warming temperatures, possibly reaching near 
60s from around the central Sound to the southwest interior, 
especially inland from the water. If Sea-Tac reaches 60, it will be 
the first time this year.  Albrecht/Mercer

.LONG TERM...From the previous long term discussion: The 
gfs/ecmwf are in fair agreement agreement on showing the ridge 
flattening Friday night and Saturday as a system rides over the 
top of the ridge. Increased cloud cover should be expected, and a 
chance of light rain, especially toward the coast and further 
north. Western Washington will still be in the warm sector so high
temperatures should again be mild, possibly close to 60. If less 
clouds prevail, some areas like the southwest interior could reach
the low 60s. But any stronger onshore flow would certainly keep 
the area stuck in the 50s but still nice compared to recent 
temperatures.

Models show mainly weak systems to affect the region early next 
week. Some solutions keep cut off lows more offshore with less 
threat of precipitation while other models are a bit wetter. Neither 
the gfs or ecmwf show any significant rainfall so a lull in the 
active weather is expected. All signs point toward more typical 
spring like weather with some clouds, some sun, and a chance of some 
showers with near average temperatures. Mercer

&&

.AVIATION...Strong wly flow aloft will continue over the region
overnight. The low level flow will remain sly. A weak wmfnt will 
move across the area late tonight or early Wed morning (PIC10). 
Areas of MVFR CIGs/VSBYs will become more wdsprd overnight.

KSEA...CIGs will bounce between VFR and MVFR categories overnight.
Expect CIGS (and occasionally VSBYs0 to be in the MVFR category 
during the day Wed. Winds will remain sly 10-15 kt.

&&

.MARINE...
A warm front will move across the area overnight, followed by a cold 
front on Wednesday (PIC10). High pressure offshore with lower 
pressure inland will result in onshore or westerly flow on Thursday.

&&

.HYDROLOGY...The heavy rain that fell on the Olympic Peninsula has
pushed the Skokomish River over flood stage a few hours earlier
than previously expected. The flood warning for the Skokomish was
updated to account for the slightly higher rises and the earlier
flood timing. Other rivers will see rises, but are not expected to
flood. 

Otherwise, rainfall is not expected to be sufficient to cause
flooding on area rivers for the next several days.

The threat of landslides has increased somewhat due to rainfall
over the past 24 hours and expected through Wednesday. A special
weather statement is out to cover this elevated risk. Albrecht

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...Flood Warning in effect for the Skokomish River in Mason 
County. 

 	 Winter Weather Advisory in effect until 10 AM Wednesday for	 the 
Cascades of Whatcom and Skagit Counties.

PZ...Small Craft Advisories are in effect for all waters except the 
central Strait of Juan de Fuca.

 	 Small Craft Advisory for rough bar in effect until 6 AM Wednesday 
for the Grays Harbor Bar.

&&

$$

www.weather.gov

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

Southwestern Washington and Western Oregon


375 
FXUS66 KPQR 290428
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR 
928 PM PDT Tue Mar 28 2017

.SYNOPSIS...Rain increasing this evening as front slowly approaches
from the west. This front will ensure quite a bit of rain tonight and
most of Wednesday. Then decreasing showers on Thursday. Still looks
like a nice and mild few days for Fri and Sat, though will see
increasing clouds on Sat. Rain threat, while not all that great,
returns for Sun into early next week.

&&

.SHORT TERM...(Tonight through Friday)...
New model QPF are a little higher than reality so far this evening,
but the radar is showing a rapid increase in rain moving inland over
the last hour.	This is the leading edge of increasing warm advection
that will move into the area overnight and Wednesday.  RAP model show
decent isentropic lift targeted at the central Oregon coast later
tonight and Wed.  Also this feature will be fairly slow moving to the
south and east, so expect abundant rainfall amount in that area. 
Also the Cascades around Mt. Jefferson will get a fair share of rain
as well. Snow level will be above 7000 ft so no snow impacts at pass
levels.  Have updated rain amount for the evening updated to reflect
new forecast.  Through Wed afternoon should see about 1" to 2.5" rain
for the coast range and Cascades while the valleys see 0.6" to 0.8". 
So far this fall/winter season, we have had two months with record or
near record rainfall (October and February). Now, with rain expected
over the next 36 hours, could add a third month. 

Models agree on dragging the trailing cold front into the region on
Wed am, so will transition to showers in the north zones. But,
another wave on the boundary will approach and move into southwest
Oregon later Wed and Wed evening. Net effect will be to slow the
fronts eastward progression, hanging it up over Lane and Linn
Counties at that time. So, will keep rain into early evening for that
area, then transition to showers late Wed evening once the front
moves east. 

Behind the front, a cooler air mass moves in, with the cold upper 
trough moving through late Wed night into Thu morning. There is
marginal instability over the coastal water for thunderstorms Wed
night.	 Expect  showers to become more orographically favored once
the upper trough  passes Thu morning. In fact, Thu likely to be lot
like it was yesterday, with mix of sun and clouds, with decreasing
threat of showers. 

Now, for last day of March, or Friday. Appears March will go out like
a lamb, under partly to mostly sunny skies and mild temperatures.
High pressure will bring lighter winds, and good deal of sunshine.
Temperatures in the 50s on the coast, with upper 50s to lower 60s
inland. If Mother Nature cooperates, could even get into the middle
60s from Salem southward.		     Rockey. 

.LONG TERM...(Fri night through Tuesday)...No changes. Previous 
discussion follows. Model agreement is better through Sat, 
with a more progressive pattern over the region. Models continue to 
show ridging east of the region on Saturday. Still looks dry and mild
on Saturday, with just increasing mid and high clouds. Now, while
there are still differences in the models, will have to keep some
minor threat of showers in forecast for Sat night into early next
week. 
 
&&

.AVIATION...Generally VFR across the area as of 03Z, except for
areas of MVFR along the S Washington and far N Oregon coast.
Coastal sites will lower to MVFR by 05Z and then become a mix of
IFR and low-end MVFR overnight through Wed morning, or possibly
into the afternoon. KONP most likely to see IFR conditions late
tonight through much of Wed. Inland TAF sites drop to MVFR late
tonight and will likely remain at MVFR into Wed afternoon. Areas
of IFR possible 12Z through 20Z Wed, especially in the Tualatin
Valley. Higher terrain becomes obscured late tonight. Secondary
trough or cold front reaches the coast around 03Z Thu, for
improved flight conditions, albeit more unstable. 


KPDX AND APPROACHES...VFR conditions as of 03Z and will prevail
until at least 08Z. Flight conditions deteriorate to MVFR
overnight as precipitation increases. IFR will be possible late
tonight through Wed morning in the Tualatin Valley. Improvement
to VFR at the terminal likely Wed afternoon. Weishaar

&&

.MARINE...Minimal changes to the current forecast. A developing
low pres out near buoy 46404 at 03Z is expected to migrate east
along a frontal boundary and make landfall along the N Washington
coast Wed morning. South wind will increase to gale force around
06Z as the low approaches the waters. GFS shows 25 to 35 kt
boundary layer wind over the waters at 09Z, then becoming sub-
gale around 15Z Wed. There will be an additional burst of wind with
the frontal passage early Wednesday morning. The NAM suggests 45
to 50 kt 975 mb wind speeds late tonight and early Wed morning,
but will cap gusts at 40 kt for now. 

Wind speeds continue to ease Wed afternoon, but veer to the NW
late Wed afternoon and early Thu evening. Models show a secondary
cold front rotating through the waters during that time. The back
side of the upper trough moves across the waters late Wed night
and Thu morning, which will likely produce solid small craft
advisory wind speeds. High pres settles over the waters Thu
afternoon for much lighter wind speeds. 

Seas are a mix of a long- period (16-18 second)and a medium (12 
second) period west swells, although the medium period swell set
appears to be waning. South wind waves will build overnight,
resulting in a chaotic sea state. Combined seas are expected to 
build to around 15 ft tonight. Seas fall below 10 ft late Wed
night or Thu morning. Weishaar

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds until 10 PM PDT this evening for 
     Coastal Waters from Cape Shoalwater WA to Florence OR out 
     60 nm.

     Gale Warning until 7 AM PDT Wednesday for Coastal Waters from 
     Cape Shoalwater WA to Florence OR out 60 nm.

     Small Craft Advisory for hazardous seas until 10 PM PDT this 
     evening for Coastal Waters from Cape Shoalwater WA to 
     Florence OR out 60 nm.

     Small Craft Advisory for Rough Columbia River Bar until 1 PM 
     PDT Wednesday.

&&


$$

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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


548 
FXUS66 KPDT 290538
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1030 PM PDT Tue Mar 28 2017

.SHORT TERM...Light rain showers have been moving across the
region over the past few hours with weak warm advection pattern. 
Expect this will increase overnight. Satellite shows larger area 
of enhanced clouds approaching the coast associated with a surface
low and warm front. Models have been indicating rain will increase
this evening and overnight as this feature moves through. A strong
upper level trough will then push the cold front through on Wednesday
with additional rain. The Cascades and northeast Oregon mountains
will receive a fairly significant rainfall over the next 36 hours
which will likely cause most rivers and streams to increase. 
Steady precipitation will turn to showers Thursday as the upper 
trough moves overhead. Could have some gusty winds associated 
with the cold front Wed night into Thursday. 94

.AVIATION...06z tafs. Rain will be increasing in coverage overnight 
and continue into Wednesday. Ceilings lowering to 030-060 with 
visibility lowering to 4-6sm -ra br at times. Winds 5-15kt overnight 
and 10-20kt Wed. 

&&

.PREV DISCUSSION... /issued 432 PM PDT Tue Mar 28 2017/ 

SHORT TERM...Tonight through Thursday night...A warm front with 
attendant moisture and lift will move into the forecast area tonight.
Rain expected beginning this evening along the east slopes of the 
Washington Cascades and rain arriving at the crests of the Oregon 
Cascades late in the evening. Rain will spread east across the 
region overnight with valley rain likely in the Lower Columbia Basin 
and the northern Foothills of the Blue Mountains as well as rain and 
snow likely in the Blue Mountains where snow levels will be 5000-
6000 feet overnight. Rain shadowing expected in central Oregon 
overnight so went with just a slight chance of rain through tonight 
for Bend and Redmond. Mesoscale models are showing rain shadowing 
immediately east of the Cascades at lower elevations during the day 
on Wednesday so significant measurable rain is not expected at the 
usual rain shadowed locations from daybreak through Wednesday 
afternoon. Snow Levels rise through the day on Wednesday to 6500-
7500 feet in the afternoon along the east slopes of the Washington 
Cascades and rise to 7500-8500 feet in the afternoon in the central 
and eastern mountains in Oregon.

The rain and high snow levels will produce runoff due to the rain 
and snowmelt, thus yielding rising creeks streams and rivers through 
the day on Wednesday and water levels continuing to rise Wednesday 
night into Thursday morning. Crests at main stem river forecast 
points are expected late Wednesday into Thursday morning.

Wednesday night a cold front enters the interior Pacific Northwest 
and moves slowly east through overnight for the best chance of 
significant rainfall. Thursday morning the cold front exits into 
Idaho while the mid/upper trough that pushed the cold front through 
the region closes off and moves southeast across central and 
northeast Oregon during the the day on Thursday, which results in 
wrap around moisture giving a chance of snow showers in the Blue 
Mountains and the Wallowa Mountains through Thursday afternoon into 
Thursday evening. Snow levels lower to around 3500 feet by Thursday 
morning in the northeast Oregon mountains. Snow showers in the 
eastern mountains taper off and end Thursday evening with overnight 
prior to daybreak on Friday morning dry areawide.  Polan

LONG TERM...Friday through Tuesday...The region looks to be under a 
weak upper ridge, and between systems, Friday and Friday night. Thus 
expect mainly dry conditions during these two periods. A moist and 
unsettled west to northwest flow looks to develop Saturday. This 
pattern then looks to persist into Monday. For now, precip chances 
on Saturday look to be limited to the mountains. Precip chances then 
are expected to increase Saturday night through Monday with the best 
chances over the higher terrain. Confidence is still low enough 
during this period to only indicate precip chances of 20 to 40 
percent. Weak ridging may move over the area Tuesday for a decrease 
in precip chances. Temps look to be near or slightly below seasonal 
through this period. 90 

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  43  59  42  54 /  70  70  80  40 
ALW  47  60  45  56 /  70  90  80  50 
PSC  46  61  45  59 /  70  60  50  20 
YKM  44  59  41  60 /  70  50  30  20 
HRI  43  60  43  59 /  70  60  60  30 
ELN  39  53  39  52 /  80  60  30  20 
RDM  42  57  36  49 /  30  60  70  30 
LGD  41  54  40  50 /  60  90 100  60 
GCD  40  57  41  47 /  40  80  90  80 
DLS  46  57  44  58 /  60  60  60  20 

&&

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

$$

94

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

Northeastern Washington and Northern Idaho


298 
FXUS66 KOTX 290525
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1025 PM PDT Tue Mar 28 2017

.SYNOPSIS...

Another round of widespread moderate precipitation will arrive 
overnight and last until early Thursday. This may aggravate 
flooding issues. Friday will bring a dry break period before more 
unsettled weather for next weekend.

&&

.DISCUSSION...

´╗┐Tonight thru Wednesday night...Our next system and strong 
moisture fetch are evident on water vapor imagery as of late this 
afternoon. A warm front lifting through the region will provide 
mild overnight lows and good isentropic lift for an expanding 
precipitation swath through the overnight hours. The previously 
mentioned moisture fetch/atmospheric river will allow PWATs to 
rise to 0.6 to 0.9, or well into the 90th percentile. Rain will be
the predominant precipitation type from this system with snow 
generally above 4-5k feet. By Wednesday night and into Thursday 
morning, the best moisture fetch begins to sink to the south and a
cold front will sweep through the area. This will focus the best 
chances for continuing precipitation over the central Idaho 
Panhandle and far southeast Washington. 

Precipitation totals continue to look healthy and have been 
trended upward some with this forecast package, especially across 
the southeast zones (where NAEFS and GEFS climatological anomalies
are highest) and across the mountains of the Idaho Panhandle and 
NE WA mountains. In general, look for 0.4 to 0.7 inches across the
eastern 1/3rd of Washington, 0.6 to 0.9 across the Panhandle 
valleys and in excess of an inch of liquid in the mountains. The 
deep Basin and Wenatchee area will probably see the lightest 
totals as the isentropic lift looks weakest in this area. The 
immediate Cascade crest will likely see liquid amounts in the 1 to
2 inch range with some of that being tied up as snowfall in the 
higher elevations. 

Impacts: The additional rainfall will likely continue to aggravate
ongoing flooding issues. At this time, hydrographs for the main
stem river show some response, but don't deviate much from their
general ongoing trends. Smaller streams and rivers, such as the
Little Spokane River at Dartford and Paradise Creek at Moscow,
will likely react with rises and low-land and lake flooding will
continue to be an issue. The other area of concern will be the
continued risk of mud and landslides in steeper terrain,
especially across far eastern Washington and the Idaho Panhandle.
For these reasons, a Flood Watch has been issued for portions of
northeast Washington and all of our Idaho Panhandle counties.
/Kalin

Thursday to Friday night: The Inland NW will remain in a 
showery pattern, before a ridge of high pressure dries things out 
for most of the region Friday, but there will be localized 
exceptions. 

First between Thursday morning and Thursday evening a stretching 
upper trough will migrate across the western United States. This 
will provide the Inland NW will broad-scale lift and unstable 
lapse rates and some pockets of weak afternoon/evening CAPE. At 
the surface a boundary stretched across southeast WA and lower ID 
early Thursday will edge away. However a deformation axis wraps 
back from a surface low sitting over the High Plains and trails 
across north Idaho into central Washington. All these factors will
mean a threat of showers, with the highest risk around the 
mountains and southeastern WA/ID and smaller chances back into the
Columbia Basin/northeastern WA. The risk will wane through the 
evening. 

As for thunderstorms, I'm not seeing any indication that instability
will be strong enough to warrant an inclusion. Overall precipitation
amounts will be highly variable, with some areas in a showery 
set-up not seeing anything. The higher risk locations, especially 
the southeastern CWA and mountains may stand a chance of seeing 
some locally moderate precipitation amounts. Snow levels will be 
around 3.5-4.5kft so this will mean the potential for some snow in
the mountain passes but impacts may be limited by the showery 
nature. It will be locally breezy from the west to northwest, 
especially toward the western and southern CWA but this too should
not be strong enough to have any significant impacts.

Then late Thursday evening and overnight, continuing into Friday,
deeper subsidence and more stable conditions start in. This will 
shut off the threat of precipitation for most of the region. The 
main threat of any linger showers will be over the Idaho Panhandle
mountains in the westerly flow. Friday night into Saturday 
morning the flow starts to flatten with another system approaching
from the west. This will lead to some increasing middle to high 
clouds from the west. A slight chance of precipitation will also 
return to the Cascade crest overnight. Patchy fog will be a threat
in the sheltered northeastern WA and ID Panhandle valleys 
Thursday night/Friday morning and again Friday night. /J. Cote'

Saturday through Tuesday: The upper level jet stream and
associated dynamics will be primarily directed toward southern BC
on Saturday. A cold front will push across the region, but 
without much support from aloft, it doesn't appear that this front
will bring much in the way of precipitation. The upper level 
trough is then progged to dig in over the region Saturday night
into Sunday. The atmosphere is expected to be conditionally
unstable by this point with showers likely expanding in coverage
through the afternoon on Sunday. Temperatures will be a bit cooler
as well with our coldest night in the extended expected Sunday 
night.

Shortwave ridging will build in over the region for the beginning
of next week, which is expected to result in a drier period for 
Monday into Tuesday. However, models are in decent agreement with
fair confidence for more precipitation to return to the region 
around the middle portion of next week. Another upper level low 
pressure system is set to develop in the Gulf of Alaska. This will
direct a better tap of Pacific moisture into the Inland 
Northwest. Snow levels will potentially rise above mountain tops 
with rain at mid elevations and snow changing over to rain at 
higher elevations as well. Although confidence is low for any 
specific impacts, this will be another period to look to for 
additional flood impacts/rock and mud slides across the region. 
/SVH

&&

.AVIATION...
06Z TAFS: Moist westerly flow will lead to rain for the TAF sites
tonight into Wednesday. Downslope flow off the Cascades into
Central Washington as well as off the Blue Mountains into the
Lewiston area should keep prevailing CIGS VFR for these areas while
a moistening boundary layer over Eastern Washington and north 
Idaho will lead to lowering CIGS with MVFR conditions becoming 
prevalent overnight into Wednesday. Steady rain may begin to
diminish over NE WA/N Idaho Wednesday afternoon but a very moist
boundary layer combined with low level upslope flow will yield an
abundance of stratus...with forecast soundings from the GFS and
NAM indicating a good chance for IFR conditions at KGEG. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        40  51  39  52  35  55 /  80 100  70  40  10   0 
Coeur d'Alene  38  49  38  50  34  53 /  80 100  80  50  10   0 
Pullman        41  51  41  49  34  52 /  60 100  90  60  20   0 
Lewiston       44  56  43  54  37  56 /  50  90  90  60  10   0 
Colville       40  48  37  52  34  55 /  90 100  60  40   0   0 
Sandpoint      37  47  35  49  33  52 /  90 100  90  50  10   0 
Kellogg        37  46  37  46  33  50 /  70 100  90  70  30  10 
Moses Lake     44  58  40  59  34  60 /  80  80  30  20   0   0 
Wenatchee      42  54  38  55  34  58 /  80  80  20  10   0   0 
Omak           41  52  36  55  33  58 /  80  90  30  20   0   0 

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Flood Watch from late tonight through Friday morning for Central 
     Panhandle Mountains-Coeur d'Alene Area-Idaho Palouse-Lewis 
     and Southern Nez Perce Counties-Lewiston Area-Northern 
     Panhandle. 

WA...Flood Watch from late tonight through Friday morning for Lower 
     Garfield and Asotin Counties-Northeast Blue Mountains-
     Northeast Mountains-Spokane Area. 

&&

$$

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