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

Western Washington


753 
FXUS66 KSEW 220930
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
230 AM PDT Mon Jul 22 2019

.SYNOPSIS...Dry weather will continue into Monday with
temperatures slightly above normal. A cold front and upper level
trough will bring showers and a chance of thunderstorms in the
Cascades on Tuesday. Strong onshore flow will prevail on Wednesday
then weaken on Thursday. Mild weather will continue into the
weekend. 

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...Upper level ridging will 
continue to weaken today as an upper trough over the Northeast 
Pacific gradually shifts closer to the region. Low level onshore 
flow has increased over the past 24 hours. This has brought some 
shallow marine air inland. This combined with lowering heights will 
knock around 10 degrees off of high temperatures over the interior 
compared to yesterday. The main area of marine stratus is still 
offshore early this morning, but should spread onto the immediate 
coastline later this morning. For the remainder of the area, it will 
be another sunny day ahead. Onshore flow increases tonight and 
Tuesday as the upper trough offshore edges closer. This should 
initiate a solid marine push tonight with stratus reaching most of 
the lowlands by daybreak Tuesday. Temperatures will cool further on 
Tuesday with the stubborn marine layer likely only yielding some 
partial afternoon clearing over the interior lowlands. Increasingly 
moist and unstable southerly flow aloft ahead of trough will produce 
a slight chance of thunderstorms over the Cascades Tuesday afternoon 
and evening. The upper trough will quickly exit to the east on 
Wednesday with a flat upper ridge moving over the area. Any shower 
threat should end by Wednesday morning. Highs will be near normal on 
Wednesday.  

.LONG TERM /THURSDAY THROUGH SUNDAY/...Low amplitude ridging will 
produce dry conditions and slightly above average temperatures 
Thursday into Friday with persistent low level onshore flow. The 
models are advertising a weak trough passing mainly to our north on 
Saturday. Apart from a chance of showers in the North Cascades, it 
looks to do little more than deepen the marine layer and cool 
temperatures a bit. Ridging weakly rebuilds for the later half of 
the weekend for perhaps a slight warmup and continued dry weather. 

27

&&

.AVIATION...An upper trough over the Northeast Pacific will slowly
shift east today with southwest flow aloft for W WA. At the surface, 
onshore flow will continue to increase  through the day. The air 
mass remains dry and stable.

Current IR satellite shows some high clouds over portions of the 
area. With onshore flow expected to increase...low level clouds are 
expected to push inland at least as far as coastal obs sites this 
morning...perhaps a bit further...but given that these clouds have 
failed to push inland in as far as said coastal sites...suspect this 
push may not be as far inland as previous shift thought. VFR 
conditions in place for most of the area and that will likely 
persist with coastal locations such as HQM likely seeing MVFR to IFR 
conditions develop at some point with the aforementioned low clouds. 
Any cloud cover that sets up there will likely recede by noon. 
Stronger onshore flow tonight should bring about better penetration 
of marine low level clouds by Tuesday morning.

KSEA...Mostly clear today. Light and variable winds this morning 
will become more southwesterly this afternoon with speeds 5-10 
knots before becoming more northerly tonight.  SMR

&&

.MARINE...Onshore flow will increase today and then continue for the 
remainder of the week with high pressure offshore and lower pressure 
inland. Small craft advisory west winds are likely each day for the 
Central and Eastern Strait of Juan de Fuca with winds peaking each 
evening. In accordance with this expectation...have hoisted another 
SCA for this area...as well as the adjacent northern inland waters 
and Admiralty Inlet...starting this afternoon and extending into 
Tuesday. Models remain consistent that gales will be possible in the 
strait Tuesday..but timing falls just outside third forecast period. 
THus...will leave any needed headlines for that time frame to future 
shifts.  SMR

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed
until then.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 5 AM PDT 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 noon today to 5 PM PDT Tuesday for 
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance 
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 11 PM PDT this 
     evening for Admiralty Inlet-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


909 
FXUS66 KPQR 220940
AFDPQR

Area Forecast Discussion
National Service Portland OR 
240 AM PDT Mon Jul 22 2019

.SYNOPSIS...Cooler today, with a chance of thunderstorms over the
Cascades. System coming onshore on Tue will usher in cooler weather,
a lot more clouds, and even some spotty light showers later tonight
through Tue night. Then, high pressure builds over the Pac NW, with
dry weather for Wed through Sat, along with seasonable temperatures.
&&

.SHORT TERM...Today through Wednesday...Water vapour channel from
NOAA satellite imagery showing southerly flow aloft over the region.
Also, can see the slug of moisture that moved from California
northward into Oregon, with bulk to east  of the Cascades. In that
flow, have had showers and thunderstorms well east of the Cascades.
However, over the Cascades and over southwestern Oregon, have seen
enhanced cloud tops with cooling, likely associated with weak
convection. But, mid levels are fairly dry, so any moisture that is
occurring is light, and likely not amounting to much once hits the
ground, if it even is doing that. So, will keep minor PoPs over the
Cascades and Oregon foothills for this am into early afternoon, with
generally some sprinkles or a few showers. 

By afternoon, most of this shower potential will have shifted on to
the east of the Cascades. However, another weak upper level vort
center will lift up across southwestern Oregon and into central
Oregon towards evening. Models vary on strength and amount of
mid/high level moisture available for convection, but think should be
instability with the steadfast southerly flow aloft and surface
heating to pop a few showers and thunderstorms over the Cascades,
mainly after 3 or 4 pm and continuing to about 8 or 9 pm. Will adjust
forecasts to reflect this trend. 

The thunderstorm threat will end over the Cascades by late evening,
thanks to the upper flow becoming more west to southwesterly. This
due to incoming upper trough offshore. Not a lot of moisture with the
trough, but enough to keep minor chance (PoPs up to 20 pct) over
along the coast and into western Washington and far northwest Oregon
for later tonight through Tue night. This trough will allow for
increasing onshore flow tonight, and moderate to strong onshore flow
for Tue and Tue night. This will keep much more widespread marine
stratus across the region tonight and Tue, with some patchy drizzle
along the coast, and possibly inland north. 

Upper trough shifts east of the Cascades Tue night, with drier
westerly flow aloft and building 500 mb heights over region for Wed.
Morning clouds will gradually burn off Wed am, but will burn off much
faster for areas south of a Newport to Salem line. This due to fairly
quick transition from northwest to northerly flow in lower levels,
allowing for rapid drying of the marine layer.	         Rockey. 

.LONG TERM...Wednesday night through Saturday...Guidance continues 
to keep the bulk of the energy to our north. This should result in 
dry and somewhat seasonable weather across the forecast area with 
temperatures in the low to mid 80s inland and mid 60s to around 70 
along the coast. Will also see periods of late night/morning stratus 
along the coast and portions of the interior, generally along the 
Lower Columbia River. Otherwise, expect plenty of sun across the 
region.  /64

&&

.AVIATION...VFR conds inland with MVFR/IFR stratus forming along
the coast. Expect onshore winds will push the stratus further
inland this morning than yesterday with KEUG seemingly more 
likely to start MVFR at best for the morning arrivals. Not
convinced stratus will make it up the Columbia much past KKLS
this morning. 

KEUG should scatter around 18Z, but a larger offshore stratus
field shown on satellite is advancing eastward and may arrive to
the coast before the radiational stratus can dissipate. Will 
give a short window of VFR before coastal conds drop back to MVFR
or worse. Elsewhere inland, the Cascades will be on the cusp of
showers and possible thunderstorms as early as this morning but
lasting through the evening hours.

Overnight, expect coastal stratus will easily penetrate inland
with all terminals possibly seeing MVFR cigs sometime around, or
shortly after, 12Z Tuesday.

KPDX AND APPROACHES...VFR with an outside chance of MVFR stratus
cigs at 015 through the morning push. Eastern approaches west of
the Cascade crest may be impacted by tstms through 23/06Z but 
confidence is low. Am fairly confident MVFR stratus cigs at or
below 015, possibly IFR, will affect operations aft 23/09Z.
/JBonk 
&&

.MARINE...Quiet weather with no significant concerns for the next
couple days. Wednesday and Thursday, another thermal trough 
strengthens along the southern Oregon coast bringing gusts up to
25 kt mainly across the central Oregon waters. Seas 6 feet or 
less through the forecast period. /JBonk

&&

.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


065 
FXUS66 KPDT 220922
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
222 AM PDT Mon Jul 22 2019

.SHORT TERM...(Today through Wednesday Afternoon)...A large scale 
upper trough will remain fixed off the coast of British Columbia. To 
the south and east, a powerful ridge of high pressure will remain 
over the Four Corners region. Between these two, we will remain 
within a southwest flow pattern.

Ongoing shower activity over northeast Oregon will continue to 
develop northward through the morning hours before diminishing by 
midday. Additional showers and perhaps a few thunderstorms will be 
possible this afternoon and evening as a weak shortwave trough moves 
from south-central into northeast Oregon. The greater chances for 
showers and storms will reside over central and northeast Oregon, 
where forcing will be greatest and aligned with daytime heating. 
Highs will come in about 5 degrees above seasonal normals in the 
middle and upper 90s most areas outside of the mountains.

On Tuesday, the larger scale upper low off British Columbia will 
lift northward as a strong and compact shortwave takes on a negative 
tilt and lifts northeast across Washington. This will drive a cold 
front through the region late Tuesday, bringing increasing winds and 
increasing chances for showers and a few thunderstorms to much of 
the region late Tuesday afternoon through Tuesday night. As much of 
the forcing with this system will remain over northern/central 
Washington, the greater chances for showers and storms will 
generally remain over north-central/northeast Oregon and south-
central/southeast Washington. Ahead of the front, temperatures will 
once again climb into the middle and upper 90s over much of the 
region.

A much drier and slightly cooler day is on tap for Wednesday in the 
wake of Tuesdays front. Highs will generally be in the mid to upper 
80s lower elevations with 70s in the mountains.

.LONG TERM...Wednesday night through next Monday...The flow will 
become westerly which will be dry and stable. The medium to long 
range models are in good agreement with this pattern to begin with. 
The result will be near seasonal normal temperatures and dry 
conditions. Winds will be mostly diurnally terrain driven, but they 
may become locally breezy in the afternoons and early evenings due 
to mixing during the heat of the day. This pattern is expected to 
persist throughout the entire extended forecast period with no 
precipitation expected. There will be a greater spread between the 
models by next Sunday with the GFS showing more of a trough pattern 
by then. The ECMWF and Canadian both show more of a ridge pattern by 
next Sunday. However, none of the models are showing any kind of 
significant weather system. Due to the uncertainty and the fact that 
all models are dry, will only make minor adjustments to the far 
extended period. This kind of pattern and resultant weather is 
typical for mid summer in the forecast area. 88

&&

.AVIATION...12Z TAFs...A weather system will bring a slight chance 
of showers and mostly afternoon and evening thunderstorms to the 
mountains and in portions of central Oregon today, which could 
impact TAF KBDN. TAF sites KPDT and KALW may also be impacted by a 
few showers this morning, which are moving mostly to the east of 
these locations. However, there are more showers and isolated 
thunderstorms developing to the south, which are moving northeast. 
All other TAF sites will remain dry for the next 24 hours. Winds 
will be mostly terrain driven. However, they will become locally 
breezy in north central Oregon this afternoon and evening affecting 
mainly TAF KDLS. 88

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  93  62  93  57 /  20  10  10  20 
ALW  96  67  98  62 /  20  10  10  30 
PSC  98  67  98  62 /  10   0   0  30 
YKM  96  63  94  56 /  10   0  10  10 
HRI  98  65  98  60 /  10   0   0  30 
ELN  92  62  89  56 /   0   0  10  10 
RDM  90  55  89  48 /   0  10  10  10 
LGD  93  63  93  57 /  20  20  20  20 
GCD  96  60  97  55 /  20  10  10  10 
DLS  93  66  89  60 /   0   0  10  10 

&&

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

&&

$$

79/88/88

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

Northeastern Washington and Northern Idaho


899 
FXUS66 KOTX 220925
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
225 AM PDT Mon Jul 22 2019

.SYNOPSIS...
Much warmer weather will arrive today and Tuesday with 
widespread highs in the upper 80s and 90s. The possibility of 
high based thunderstorms will also develop during this hot period 
especially Tuesday night. A cold front passage will moderate 
temperatures back to near normal Wednesday, but will bring with 
it breezy winds. Dry and seasonably warm conditions are expected 
for the end of the work week.


&&

.DISCUSSION...
Today: Very tricky and difficult forecast for the next 36 hours. 
Some elevated showers have been moving up overnight from eastern 
Oregon. They are already into the LC Valley and Camas Prairie. 
Have not been able find any precip reaching the ground yet in our 
forecast area. Lightning has waned overnight, but the NAM is 
showing aft 5am some stronger elevated CAPE moving into the 
aforementioned area. So have kept our threat of thunder through 
the morning hours. Then in the afternoon the chance of showers and
thunderstorms expands across much of eastern WA and N ID, as well
as along the Canadian border of the northern Cascades and 
Okanogan Valley. We are expecting some moderately dense mid and 
high level clouds this morning into the early afternoon. This 
could hamper our daytime highs. The models seem to think the 
thicker clouds will move out of the area by mid to late afternoon 
and we will still see high temperatures probably reached early 
this evening. 

Tonight and Tuesday: The threat of thunderstorms will continue
through the evening and overnight hours...and through Tuesday.
Once again, elevated instability will be moving in and stretch 
from the Blues into the north ID Panhandle. Then on Tuesday the 
threat expands in the afternoon into portions of the Cascades and 
Okanogan Valley. The models had been hinting at convection in the 
Cascades yesterday and today the confidence continues to grow and 
expand across the area. Temperatures will be just a few degrees 
warmer, for potentially the warmest day we have seen this summer 
for many locations. /Nisbet

Tuesday night and Wednesday: Everything comes together for an active weather
event on Tuesday night. The hot temperatures in the 90s, combined with dew
points in the lower 50s, create a rather unstable atmosphere on Tuesday
afternoon. Meanwhile a very strong negative-tilt short wave moves onshore. This
is an excellent pattern for severe weather in our area. However, the timing is
not good for severe storms. The short wave moves through our area overnight,
rather than during the afternoon. This later arrival time allows the lower
atmosphere to decouple, decreasing the instability. 

Even so, there is still a large amount (500-1000 J/kg) of elevated CAPE, along
with about 1 inch of precipitable water. So as this short wave swings through 
in the evening, thunderstorms are expected to develop around 5pm along the 
WA/OR border, spreading into the upper Columbia Basin by 8pm, and then covering
most of eastern WA and the Idaho Panhandle by midnight. The main threat will be
strong wind gusts (from the thunderstorms and the cold front) and small hail. 
Expect brief downpours, but the storms will be moving too fast to cause any 
flooding concerns. Lightning could start some fires, and the gusty winds could
help spread fires. But the rain and high humidity should limit the number of 
fire starts and spread.

The system exits the region quickly by Wednesday morning, with just a few
morning showers over the northern/eastern mountains. Temperatures will be
about 15 degrees cooler on Wednesday.  RJ

Wednesday night through Sunday...From mid week onward there is
loose model agreement featuring a couple days of warming under a
flat ridge followed by a cold front passage on or about Saturday.

For Thursday and Friday a surface thermal trough will re-
establish itself over the Columbia Basin as a short wave ridge 
pops up over the area. This will allow temperatures to rise back 
into the mid 80s on Thursday and peak in the upper 80s to lower 
90s on Friday with light winds and abundant sunshine. The expected
arrival of the next weak Pacific short wave disturbance Friday 
night or Saturday does not appear to bring any appreciable 
precipitation threat but may manifest itself as a dry and breezy 
period on Saturday with temperatures cooling back into the mid 80s
over most locations with the rest of the upcoming weekend 
remaining dry and benign with seasonably normal temperatures.
/Fugazzi

&&

.AVIATION...
06Z TAFS: Dry conditions tonight with VFR conditions. 
After 10Z expect to see mid and high level clouds increase 
from the south, with an increased chance for spotty high based 
early morning showers and thunderstorms at KLWS/KPUW aft 12Z 
Monday and near KGEG and vicinity near 15Z Monday. /Pelatti


&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        90  61  93  58  78  52 /  10  10  10  50   0   0 
Coeur d'Alene  89  60  93  58  76  52 /  20  10  20  60  10   0 
Pullman        90  58  92  55  75  49 /  30  20  20  60   0   0 
Lewiston       97  68  99  65  84  58 /  20  20  10  50   0   0 
Colville       91  53  97  53  83  45 /  20   0   0  50  20   0 
Sandpoint      84  58  91  58  75  50 /  20  20  10  60  20   0 
Kellogg        88  63  92  61  73  54 /  20  20  20  60  10   0 
Moses Lake     96  63  95  59  84  55 /  10  10   0  30   0   0 
Wenatchee      93  67  92  62  81  58 /   0  10  10  10   0   0 
Omak           93  63  95  61  83  56 /  10   0  10  50  10   0 

&&

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

&&

$$

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