Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus66 kpqr 192113 
afdpqr

Area forecast discussion
Weather Service Portland or
213 PM PDT Wed Jun 19 2019

Synopsis...the cooling trend which began Tuesday will continue today
as strong onshore flow persists across the pac northwest. Areas of morning
clouds will give way to partly to mostly cloudy skies and slightly
below normal temperatures for this afternoon. Thursday brings the
coolest day of the week along with a chance for showers.
Dry weather and seasonable temperatures return Friday and Saturday,
followed by the potential for cooler temperatures and scattered
showers again Sunday through Tuesday.

&&

Short term...tonight through Saturday...temperatures remain several
degrees cooler today than this time yesterday as the upper trough
continues to swing closer to the region. Meanwhile, krtx and klgx
Doppler radar does depict a few light showers swinging across the far
northwestern portions of the forecast area. This upper low pressure
will slide across the region on Thursday, maintaining another cooler
day with more abundant cloud cover and some light showers holding
temperatures several degrees below seasonal normals. A shortwave
embedded in the flow aloft will provide a mechanism for some more
widespread showers late tonight, but while more widespread in areal
extent these showers will nonetheless remain quite light. Showers
will be most widespread along the coast and in the terrain of the
Coast Range and Cascades. Snow levels may briefly lower to around
5000 feet Thursday, perhaps resulting in a quick dusting for the
higher elevations of the Cascades. Meanwhile, the Cascade passes
should remain just wet with perhaps a few occasional wet snowflakes
mixing in.

The upper low then slides east into The Rockies and the Great Basin
on Friday, which will lead to heights beginning to rise a bit above
the region. While some decent cloud cover will remain in the morning,
flow aloft will turn to be from a drier, northerly direction. This
will allow temperatures to rebound to normal values by the afternoon.
Little change on Saturday with onshore low-level flow bringing
morning clouds and some afternoon clearing. This should result in a
rather pleasant Saturday afternoon across the Willamette Valley as
temperatures will be close to seasonal normals.

Long term...Saturday night through Wednesday. However, the relative
break from Friday and Saturday will be short-lived with a change in
the pattern back to a more unsettled regime by late Saturday or early
Sunday. A deeper marine push will lead to more widespread cloud cover
by Sunday morning, with the potential for some light precipitation -
especially across the northern half of the forecast area. While
still some run-to-run variations in guidance, the model consensus
still depicts an upper trough to be near or over the region through
much of the first half of next week. This will maintain another round
of afternoon temperatures holding several degrees below normal and at
least some chance for showers through the week. As a result, the
temperature forecast was trended toward a model blend and away from
the statistical MOS guidance that would tend to trend temperatures
back to seasonal normals. The deep upper trough eventually swings
across the forecast area around midweek, but guidance does suggest
that the unsettled pattern will continue to the second half of next
week.

&&

Aviation...upper level trough settling over the forecast area
this afternoon. Onshore flow continues with the primary cloud
cover at 20z over northwest Oregon, generally north of ksle, and SW
Washington. Cigs are mainly 035-045. VFR conditions expected to
prevail into the evening. The South Washington and far north
Oregon coast will likely hold on to broken cloud cover the longest.
Similar pattern this evening and tonight compared to last night,
with MVFR to low-end VFR cigs developing along the coast north
of konp between 03z and 06z and then spreading to the interior
lowlands overnight into Thu morning. Increasing likelihood of
MVFR cigs and/or vis late tonight through Thu morning across SW
Washington and far north Oregon coast and Coast Range.

Kpdx and approaches...VFR at the terminal as of 20z, with cigs
045-060. VFR prevails through at least 10z Thu. Expect clouds to
fill back in late tonight or Thu morning, but cigs likely to
remain low-end VFR. Weishaar

&&

Marine...20z buoy reports indicated near square-sea conditions
with dominant periods 6-8 seconds and wave heights 5-6 ft. Spectral
analysis for buoy 029 valid 19z showed peak wave energy around 8
to 9 seconds, but a secondary peak around 6-7 seconds. Latest
wave guidance continues to indicate 8-9 second dominant periods.
Will hold off on issuing an advisory, but next shift will need to
closely monitor.

Otherwise, not much change to the pattern expected through the
rest of the week. Surface high pressure will remain over the NE
Pacific, with a thermal trough over norther California. This will
continue the northerly wind regime. There is potential for some
gusts of 20-25 kt south of Heceta Head this afternoon and
evening. Thereafter, expect winds to be 20 kt or less through the
weekend and early next week. A weak low pressure system will
settle over the waters later in the weekend or early next week.
This will keep winds light and potentially turn them to the
south/southwest.

Seas will remain around 6 to 7 ft through the next few days,
possibly touching 8 ft occasionally. The seas then subside to
around 5 ft over the weekend and into early next week. Weishaar

&&

Pqr watches/warnings/advisories...
or...none.
Washington...none.
Pz...none.

&&

$$

Interact with US via social media:
www.Facebook.Com/nwsportland

National Weather Service Glossary of Abbreviations