Scientific Forecaster Discussion
fxus66 kpqr 242232
Area forecast discussion
National Weather Service Portland or
332 PM PDT Sat Jun 24 2017
Synopsis...high pressure over the Pacific northwest will bring
unseasonably hot, potentially record breaking temperatures across
much of northwestern Oregon and southwestern Washington Saturday and
Sunday. A marine push should result in cooler temperatures beginning
late Sunday and Monday. Dry northwesterly flow sets up next week
across the region, bringing more seasonable temperatures and a
pattern of morning clouds and afternoon sunshine.
Short term...tonight through Tuesday...not much change in the
overall forecast in the short term, but some details to work out.
Current temps in the mid 90s in the interior valleys. Most of the
coastal areas range from the mid 80s on the central coast to around
90 at the north coast.The thermal trough is hanging just on the
coast this afternoon with northeasterly winds at the north coast
giving some downslope warming to some spots such as 95 at Tillamook.
The thermal trough is a little inland at the central Oregon coast
hence the slightly lower temperatures.The offshore flow weakens
tonight and turns onshore Sunday bringing relief to the coast, Coast
Range, and even the far southern portions of the Willamette Valley.
However the the north interior zones will see about the same
temperatures as today.Will keep the heat advisories/warning plans
unchanged. The advisories for the Coast Range and south Willamette
Valley zone end tonight, with the remainder of the interior lowlands
& Cascade foothill zones ending Sunday night. The thermal low
pressure will shift east of the Cascades Sunday night and result in
the entire forecast area cooling considerably by Monday.
As the upper ridge bringing the heat shifts east, a weak upper level
impulse lifting northeastward into northern California and Oregon
Sunday night and Monday will help to destabilize the atmosphere is it
brushes our southern County Warning Area. At this point, it appears there is a chance
of thunderstorms grazing primarily the Lane and Linn County Cascades
as well as the central Oregon coast and even the south half of the
interior lowlands. These will be elevated thunderstorms, so we'll
need watch for changes to the instability/moisture to expand or cut
back on the thunderstorm coverage. /Mh
Long term...Tuesday night through Saturday...low level onshore flow
will continue through much of the long term period. Models continue
to show a broad upper level trough moving across the forecast area
late Tuesday/Wednesday which will bring an increase in cloud cover
along, with some patchy morning fog or drizzle on the north coast.
Expect much more seasonal temps on Wednesday afternoon. Upper level
ridging will start to build over the pac northwest late next week which
will bring slightly warmer temps. The good news is that the ridge
will not be as strong next week which will prevent temps from
becoming outrageously hot. /64
Aviation...high pressure and offshore flow will bring
predominantly VFR conditions to most taf sites through 00z
Monday. The main exception to this will be along the coast
where a southerly wind reversal will bring IFR conditions to konp
sometime between 04-08z Sunday before transitioning to MVFR
conditions later on Sunday.
Kpdx and approaches...high pressure and offshore flow will bring
VFR conditions through 00z Monday. /Neuman
Marine...high pressure over the northeast Pacific will continue
well into next week. In the immediate short term, a weak low
pressure will move northward across the waters over the next 36
hours. This will result in gusty north to northeast winds across
the outer waters late this afternoon and evening before
southerly winds spread northward across all the waters tonight
A Summer-like northerly wind pattern then looks to return late
Monday or Tuesday and continue through much of next week. This
should result in northerly winds peaking generally each afternoon
and evening across the waters...with the strongest winds
generally occurring across the waters off the central Oregon
or...excessive heat warning until 9 PM PDT Sunday for western
Columbia River gorge.
Heat advisory until 9 PM PDT Sunday for Cascade foothills in
Lane County-central Columbia River gorge-central
Willamette Valley-greater Portland Metro area-lower
Columbia-northern Oregon Cascade foothills.
Heat advisory until 9 PM PDT this evening for central Coast
Range of western Oregon-Coast Range of northwest Oregon-
south Willamette Valley.
Washington...excessive heat warning until 9 PM PDT Sunday for western
Columbia River gorge.
Heat advisory until 9 PM PDT Sunday for central Columbia River
gorge-Greater Vancouver area-I-5 corridor in Cowlitz
County-South Washington Cascade foothills.
Heat advisory until 9 PM PDT this evening for Willapa Hills.
Pz...Small Craft Advisory for winds until 11 PM PDT this evening for
waters from Cape Shoalwater Washington to Florence or from 10 to
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