NWS Portland, OR wrote its last area forecast discussion before the first event at Jun 12, 9:27 PM PST, 2 hours 33 minutes earlier.
Area forecast discussion, Jun 12, 9:27 PM PST, 2 hours 33 minutes before
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
1027 PM PDT Fri Jun 12 2026
...Updated aviation discussion...
.SYNOPSIS...Minimal change in the forecast overall. Upper level
high pressure builds over the far northeast Pacific into
western WA/OR over the next several days, ushering in a
prolonged stretch of dry and hot conditions. Daytime
temperatures increase significantly this weekend into early next
week, peaking Sunday and Monday with interior lowlands in the
upper 90s to around 100 degrees. Low temperatures will not
provide much relief from the heat. Heat related impacts are
anticipated for much of the region with widespread Moderate to
High HeatRisk. Temperatures will trend cooler for Wednesday
onward with the return of onshore flow.
&&
.SHORT TERM...Now through Monday Night...High pressure continues
to build over the region today which is setting the stage for a
stretch of hot and dry conditions. Today has been fairly normal
with highs in the mid to upper 70s inland, and near 60 along the
coast. While temperatures were mild today, that will not be the
case over next several days.
On Saturday, we will see highs rise into the 80s but the big
consideration is actually wind. The overall flow will transition
into an offshore pattern which will add a mechanical warming
mechanism to the environment. As the easterly flow comes up and
over the terrain, it will not only mix down warm air aloft, but
it will also compress the air at the surface and thus cause
increased warming. This flow pattern will also cause winds to
ramp up within the Columbia River Gorge, and within the
Willamette Valley. Overall, the wind speeds are not unheard of
for this time of year, but rather they are impactful to some of
the industries like wildfire. More details on this below.
Temperatures rise further on Sunday into Monday as the ridge
axis aligns to the coastline. Daytime temperatures are expected
to quickly increase into the upper 80s to low 90s on Saturday
then to the mid to upper 90s for Sunday and Monday for the
interior lowlands and portions of the OR Coast Range. The coast
will be much warmer than normal as well, peaking in the 70s each
day and near 80 degrees on Sunday. With the newest forecast, the
HeatRisk for the coast has increased to Moderate and there was
enough confidence in an increased heat day to issue a Heat
Advisory for the coast. Probabilities for temperatures
exceeding 95 degrees are around 70-90% between Salem and
Vancouver and 50-70% for the rest of the interior lowlands on
Sunday. There is less than a 5% chance for the Cowlitz Valley
lowlands and Gorge. On Monday, those probabilities for 95
degrees F rise considerably with the NBM showing around a
85-99% chance of temperatures greater than 95 degrees F in the
Valley and around 30% in the Longview area. With Monday being
the hottest day in the forecast, there is around a 50% chance of
temperatures of 100 degrees or more from Salem northward.
Something we continue to monitor are the overnight low
temperatures. Typically we will see cooling overnight that
brings much needed relief. However, in this pattern we are
seeing very little as overnight lows are lingering around 65
degrees F in the interior lowlands where we see the highest
daytime temperatures. Low temperatures could even remain
above 70 degrees in some locations with a 30-40% chance for the
greater Portland-Vancouver Metro area Sunday night into Monday
morning and less than a 10% chance on Monday night into Tuesday
morning.
As previously mentioned, there are some fire weather concerns in
areas with cured grasses and finer fuels Saturday into Monday
due to hot, dry, and breezy conditions. The thermal trough will
bring breezy conditions within the western Columbia River
Gorge/Cascades gaps and the Willamette Valley Saturday through
Sunday night. As daytime highs increase, relative humidities
will also decrease to near critical levels. Based on feedback
from area partners, fuels are not quite cured enough to consider
any Red Flag Warnings at this point, but there is uncertainty
on how the fuels will be impacted by the continuous days of dry
and hot conditions. Currently, there is around a 15-30% chance
of relative humidity being below 25% and winds being greater
than 15 mph on Saturday and Sunday. Be aware of potential
ignition sources such as vehicle chains dragging on the
pavement, hot vehicle components, sparks created by power tools,
and cigarette butts as all of these could easily result in the
ignition of cured grasses and dry, fine fuels. Live vegetation
and larger fuels may not have enough time to dry out prior to
the dry and breezy conditions, but this is a variable that is
being closely monitored by our State and Federal Fire Partners.
-27
&&
.LONG TERM...Tuesday through Friday...Ensemble guidance
indicates high pressure continues Tuesday with heights
beginning to lower along with 850 mb temperatures, which would
allow for lowering temperatures on Tuesday. However, there is
uncertainty in the forecast spread of both of these elements,
leading to uncertainty in the high temperature for Tuesday.
Additionally, it is not uncommon for models to degrade highly
amplified ridges such as this one too early in the extended
forecast period. There is no robust weather system in the models
that is causing the lowering heights, so there is the potential
that the high pressure may not break down as much as ensembles
indicate on Tuesday. NBM still indicates warm daytime
temperatures at least in the upper 80s for the interior
lowlands. Ensembles are in good agreement that the surface
thermal trough over OR will break down sometime Monday into Tuesday,
so Tuesday is not expected to be quite as warm for the coast
and Coast Range. With the flattening ridge, we there is the
potential for a more unique wind direction pattern though. We
will see a transition to northwesterly winds which will usher in
cooler air to the northern portions of the forecast area while
the southern zones will remain warmer. Therefore, there may be a
5 degree spread between the north and south on Tuesday. But, if
the ridge remains amplified, that difference will be less
significant. Either way, past heat events have shown that
impacts from the heat can continue despite a cool- down,
especially since morning low temperatures are expected to remain
very warm Tuesday morning.
Ensemble guidance indicates the high pressure axis shifts west
back over the E Pacific Wednesday and Thursday as a strong upper
trough digs into the Midwest. However, uncertainty in the
strength of the trough leads to uncertainty in the high pressure
over the Western US/E Pacific. There is high confidence that
temperatures will be quite cooler than Sunday and Monday, but
50-60% of ensemble members still keep just enough high pressure
over the region for high temperatures to remain in the low to
mid 80s for the interior lowlands. -HEC
&&
.AVIATION...High pressure will maintain VFR conditions with clear
skies through the TAF period across all terminals. Tonight, variable
winds around 5 kt or less inland with light offshore winds along the
coast. After 15-18z Sat, offshore pressure gradients will tighten
and support northerly to northeasterly winds across the region, with
gusts up to 20-25 kt at any given terminal. After 03-04z Sun, winds
should gradually weaken as pressure gradients ease.
In addition, temperatures between 90 to 100 degrees F are forecast
across the Willamette Valley Saturday through early next week. Be
aware of high density altitude which may reduce aircraft
performance.
KPDX AND APPROACHES...VFR with clear skies through the TAF period.
Light northwesterly winds around 5 kt or less overnight, turning
more northeasterly after 16-18z Sat with gusts up to 20 kt through
the afternoon. Winds weaken in the evening after 03z Sun. -10
&&
.MARINE...Expect a typical summertime pattern persist into next
week as high pressure builds offshore. Diurnal northerly winds
will strengthen, peaking each afternoon and evening. Expect winds
of 15-20 kt with gusts up to 25 kt south of Cape Falcon on Friday,
increasing to 15-25 kts with gusts up to 30 kts on Saturday.
Overnight, wind gusts may fall below Small Craft Criteria for the
inner water zones, but still expecting gusts up to 25 kt for the
outer waters. Will maintain the current suite of Small Craft
Advisories, but they could get extended through Sunday as there is
minimal changes in overall conditions. Seas 4-7 ft at 9-11
seconds with a persistent westerly swell.
Long-range guidance brings a more active weather pattern towards
the end of next week. Which could result in seas near 10 ft as
well as gusts up to 30 kt, but overall confidence in this pattern
change is low at this time.
&&
.CLIMATE...
Record high temperatures and warm low temperatures for Sunday,
June 14
High Temperatures: Warm Low Temperatures:
Portland Int'l 89F (1988) 62F (1985)
Vancouver, WA 93F (1986) 61F (1931)
Hillsboro 96F (1961) 60F (1963)
McMinnville 93F (1986) 59F (1936)
Salem 92F (1961) 59F (1936)
Eugene 92F (1914) 57F (1993)
Astoria 86F (1914) 58F (1972)
Record high temperatures and warm low temperatures for Monday,
June 15
High Temperatures: Warm Low Temperatures:
Portland Int'l 95F (1966) 60F (1969)
Vancouver, WA 95F (1930, 1966) 62F (1961)
Hillsboro 99F (1961) 60F (1963)
McMinnville 96F (1961) 59F (1936)
Salem 100F (1966) 59F (1931)
Eugene 96F (1966) 60F (1961)
Astoria 91F (1966) 58F (1997)
Record high temperatures and warm low temperatures for Tuesday,
June 16
High Temperatures: Warm Low Temperatures:
Portland Int'l 95F (1958) 60F (2012)
Vancouver, WA 92F (1961) 67F (1966)
Hillsboro 100F (1961) 65F (1961)
McMinnville 98F (1961) 59F (1966)
Salem 97F (1961) 61F (1961)
Eugene 95F (1961) 62F (1961)
Astoria 87F (1958) 59F (1997)
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory from 11 AM to 11 PM PDT Sunday for ORZ101>103.
Heat Advisory from 11 AM Sunday to 11 PM PDT Tuesday for
ORZ104>108-113>119-121>125.
Extreme Heat Warning from 11 AM Sunday to 11 PM PDT Tuesday for
ORZ109>112-120.
WA...Heat Advisory from 11 AM to 11 PM PDT Sunday for WAZ201.
Heat Advisory from 11 AM Sunday to 11 PM PDT Tuesday for
WAZ202>205-208-210.
Extreme Heat Warning from 11 AM Sunday to 11 PM PDT Tuesday for
WAZ206-207-209.
PZ...Small Craft Advisory until 5 AM PDT Sunday for PZZ252-253-272-
273.
&&
www.weather.gov/portland
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