Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Portland or
1113 PM PDT sun Jul 13 2014
Synopsis... an upper level low pressure system will continue to
move across the Pacific northwest tonight. Showers decrease
throughout thenight. High pressure rebuilds over the area with a
return to a summertime weather pattern with coastal clouds and
varying amounts of inland intrusion. Inland temperatures will remain
well above normal through the latter part of the week.
Update...radar shows showers rotating around an upper low wrapping
back around into southwest Washington and have done a quick update
to increase probability of precipitation over the SW Washington coast and the Willapa Hills.
Do not expect the showers to move further south since the low
is moving to the NE. Tj
Short term...tonight through Wednesday...thunderstorms and
lightning that occurred earlier today waning this evening with
convection shifting into the Cascades and eventually east and north
of our area. There has been quite a bit of stratus lying underneath
the elevated convection today. This combined with convective clouds
held temperatures down in the pleasant range. As the showers
departed this evening...the last few frames of visible satellite
imagery before darkness set in revealed coastal stratus well into
the Coast Range and an extensive sheet of stratus in the foothills
of Lane and Linn counties. For tonight...some lingering showers and
perhaps an isolated thunderstorm may persisting the northern
Cascades until the upper low finally leaves our area early tomorrow
By Monday morning...expect the stratus to fill in the valley as we
get a reinforcing marine intrusion up the Columbia and seeping
through the Coast Range gaps. Temperatures tomorrow will likely
recover significantly from today as heights rapidly rebuild and skies
continue to clear. May get some fair weather cumulus over the terrain
and some spotty clouds over the valley. Stratus will have a hard time
burning off the north coast but should ease off the central coast.
Very warm and dry conditions return Tuesday and Wednesday with coastal stratus
backing slightly offshore during the late afternoon
and early evening. Tw
Long term...Wednesday night through Saturday...models generally
agree on an upper level trough over the region toward the latter part
of the week. This pattern should trend temperatures to more seasonal
Aviation...convection over the area has ended. Entrenched
stratus along the coast and well into the coastal mountains with
IFR and terrain obscuring conditions continuing through Monday. Konp
and vicinity may briefly have some VFR conditions late Monday afternoon.
Inland...satellite and metars show indicate extensive ceilings around
2500-3000 feet generally east of Interstate 5. This should expand
overnight. Expect ceilings to lower into the 1500 to 2500 feet range.
Local IFR conditions possible on the lower Columbia River to kpdx.
Conditions improving midday Monday with VFR for afternoon.
Kpdx and approaches...patches of MVFR ceilings around 3000 feet in the
area this evening will likely expand overnight. There is a 40
percent chance of ceilings near 1000 feet 12z-16z Monday. After 16z
conditions improving with VFR expected 19z Monday.
Marine...high pressure will remain over the NE Pacific through the week.
North to northwest winds likely to increase Monday afternoon as high
pressure builds offshore. Appears small craft criteria for winds
are likely over the central Oregon coastal waters by middle to late
Westerly long period swell...running about 3 feet crossing the
waters. Models indicate this will continue until Monday night
when the northwest winds generate a more dominant shorter period
7-9 second swell. Even though there is relatively low swell...with
the long period and the very strong Ebb current on the Columbia
River bar rough bar condition are expected during the strong Ebb
Monday morning. Schneider/mh
or... heat advisory from 11 am Monday to 11 PM PDT Tuesday for
foothills in Lane County-Cascades in Lane County-central
Coast Range of western Oregon-central Columbia River gorge-
central Willamette Valley-Coast Range of northwest Oregon-
greater Portland metropolitan area-lower Columbia-northern Oregon
Cascade foothills-northern Oregon Cascades-south Willamette
Valley-Upper Hood River Valley-western Columbia River gorge.
Washington...heat advisory from 11 am Monday to 11 PM PDT Tuesday for central
Columbia River gorge-Greater Vancouver area-I-5 corridor in
Cowlitz County-South Washington Cascade foothills-South
Washington Cascades-western Columbia River gorge-Willapa
Pz...Small Craft Advisory for winds from 3 PM Monday to 4 am PDT
Tuesday for coastal waters from Cascade Head or to
Florence or out 60 nm.
Small Craft Advisory for rough Columbia River bar from
5 am to 9 am PDT Monday.
More weather information online at...http://weather.Gov/Portland
Interact with US via social media
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.