Area Forecast Discussion
Issued by NWS Portland, OR
FXUS66 KPQR 242149 CCA
Area Forecast Discussion...Corrected
National Weather Service Portland OR
242 PM PDT Wed Aug 24 2016
Fixed formatting of the climate section.
.SYNOPSIS...An upper level ridge and offshore winds will result in
warming through Friday. A thermal trough over the Willamette Valley
Thursday and Friday will support afternoon inland temperatures
peaking in the upper 90s, with localized temperatures to 105. Onshore
winds will return Friday night and Saturday. A persistent upper level
trough will continue onshore winds and inland morning clouds for near
or below seasonal temperatures Saturday through mid next week.
.SHORT TERM...(Tonight through Saturday)...An upper level ridge
building into the Pac NW, combined with a thermal trough and offshore
winds over NW Oregon and SW Washington, will result in another
stretch of hot weather through Friday. Expect temps to peak in the
low 90s across the interior this afternoon, but this is just the
beginning as highs for Thursday and Friday will be even warmer.
The thermal trough over southern Oregon will continue to build north
overnight and looks to be over the Willamette Valley on Thursday.
This will help to strengthen the offshore flow across the forecast
area which will allow inland temps to warm into the upper 90s, with
isolated areas a few degrees over 100 possible. Offshore flow should
be strong enough on Thursday to allow coastal temps to warm into the
80s. Not much change is expected for Friday as the general pattern
remains similar to Thursday. With the hot weather pending and not
much change expected in the temps will continue the current heat
advisory through Friday evening. Despite the coast warming into the
80s on Thursday weak onshore flow will return by Friday so they
continue to not be included in the advisory.
The upper level ridge looks to weaken late Friday with the thermal
trough shifting east of the Cascades. This will bring a cooler air
mass to the forecast area Friday night as onshore flow increases
across the region. Models continue to suggest that we will see a
southerly surge Friday night which should bring the return of marine
stratus and patchy fog to the coast, with marine stratus filtering
locally inland Saturday morning. Expect any stratus in the interior
to dissipate Saturday afternoon with temps a good 10 to 15 degrees
.LONG TERM...(Saturday night through Wednesday)...General period of
troughiness settles in to the PacNW by the latter part of the weekend
and into early next week. This will bring cooler temperatures,
cloudiness, and chances for showers to the area. The best chance of
showers will be for far NW Oregon and SW Washington as well as marine
areas Sunday evening through Monday as a weak low forms off the coast
on Sunday night and moves into Vancouver Island on Monday night.
There are still timing and strength differences between the ECMWF and
GFS, but either way, confidence in precipitation is high enough to
introduce PoPs during the period with highest chance during the day
on Monday. /Bentley
.AVIATION...With offshore flow, generally VFR conditions continuing
tonight into Thu. A small chance for some ifr fog to develop along
the coast this evening, mainly KONP, between 01z and 05z before winds
KPDX AND APPROACHES...VFR tonight and Thu.
.MARINE...High pressure will continue over the northeast Pacific
through end of the work week. Thermal low pressure over western
Oregon will produce breezy northerly winds across the waters with
short period choppy seas of 4 to 7 ft through Friday.
Winds have been slow to pick up early this afternoon, but still looks
marginally likely for seeing some gusts in the 20 to 25 kt range this
evening in the southern waters, so will hang on to the small craft
advisory there. Probably a slightly better prospect for small craft
winds in the southern waters late Thu and Thu night as the thermal
induced trough intensifies. With a small short period swell from the
nw continuing, steep seas will remain but with heights peaking in the
4 to 7 ft range through Fri.
Winds diminish some by Sat as the trough of low pres moves inland.
.CLIMATE...Record breaking temperatures are possible Thursday and
Friday. The table below lists the current forecast high temperatures
and the daily record high temperature for selected locations. The
`(YEAR)` is the year that the daily record was last set or tied.
LOCATION THURSDAY, AUG 25 FRIDAY, AUG 26
FCST T/REC T (YEAR) FCST T/REC T (YEAR)
Vancouver, WA 96 / 96 (2010) 98 / 99 (1935)
Portland, OR 96 / 94 (2010) 98 / 100 (1986)
Troutdale, OR 96 / 95 (1986) 96 / 103 (1986)
Hillsboro, OR 98 / 96 (2010) 99 / 100 (1986)
McMinnville, OR 98 / 96 (1996) 99 / 99 (1924)
Salem, OR 99 / 97 (1967) 99 / 98 (1986)
Eugene, OR 98 / 97 (2010) 99 / 96 (2014)
Hood River, OR 94 / 95 (1996) 95 / 98 (1986)
OR...Red Flag Warning from noon to 9 PM PDT Thursday for Central
Oregon Cascade Foothills-Central Oregon Coastal Strip-East
Slopes of the Central Oregon Coast Range-Mt. Hood National
Forest -West of Cascade Crest-North Oregon Cascade
Foothills-North Oregon Coast-North Oregon Coast Range-
Willamette National Forest-Willamette Valley.
Heat Advisory from 2 PM Thursday to 8 PM PDT Friday for Cascade
Foothills in Lane County-Central Coast Range of Western
Oregon-Central Columbia River Gorge-Central Willamette
Valley-Coast Range of Northwest Oregon-Greater Portland
Metro Area-Lower Columbia-Northern Oregon Cascade
Foothills-South Willamette Valley-Upper Hood River Valley-
Western Columbia River Gorge.
Red Flag Warning until 8 PM PDT this evening for Willamette
WA...Red Flag Warning from noon to 9 PM PDT Thursday for Clark
County Lowlands-East Willapa Hills-Extreme South
Washington Cascades-South Washington Coast Including The
West Willapa Hills.
Heat Advisory from 2 PM Thursday to 8 PM PDT Friday for Central
Columbia River Gorge-Greater Vancouver Area-I-5 Corridor
in Cowlitz County-South Washington Cascade Foothills-
Western Columbia River Gorge-Willapa Hills.
PZ...Small Craft Advisory for winds until 3 AM PDT Thursday for
Waters from Cascade Head to Florence OR from 10 to 60 nm.
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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.