Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 230415
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
914 PM PDT Fri Jul 22 2016

.SYNOPSIS...Upper level low pressure now centered to the east of the
area near the Oregon/Washington border will slide into Eastern
Washington this evening. High pressure will then strengthen over the
region through the weekend with daytime temperatures returning to
seasonal normals. High pressure holds through much of next week with
temperatures warming slightly each day before reaching well
above normal by the end of next week.

&&

.SHORT TERM (Friday night through Monday)...Last daylight visible
satellite loops show slowly dissipating clouds inland. However lots
of stratocumulus remains over the waters and weak onshore flow will
bring cloud back to most of the coast and northern inland zones
overnight. Further south, northerly flow with a slight offshore
component should keep most of the south valley and mountain zones
mostly cloud free. Regional radar shows very light showers over the
south washington coastal waters.  These showers should end this
evening, but another weak shortwave will clip the northern Oregon and
southern Washington coastal areas and may bring some light patchy
drizzle to the coast late tonight through Saturday morning.

With stable westerly flow remaining in place, expect many areas to
see scattering in clouds for at least a partly sunny day by the late
afternoon. Temperatures will be back to around seasonal norms
tomorrow - but perhaps a few degrees cooler than normal across the
northern third of the area where clouds may linger a bit longer in
the day.

500 mb heights continue to rise on Sunday, with models suggesting 850
mb temperatures into the upper teens. This would support temperatures
well into the 80s, climbing a few degrees above normal.
A weaker surface pressure gradient Saturday night will prevent much
inland cloud cover overnight Saturday into Sunday morning. This
should allow temperatures inland to climb well into the 80s on
Sunday. Little change for Monday with temperatures well above normal
and plenty of sunshine for the forecast area. However, models suggest
an approaching shortwave later Monday could help to bring some
additional cloud cover into Monday evening as the onshore low-level
gradient increases. mhCullen

.LONG TERM...(Monday night through Friday)...The flat upper level
ridge will continue to dominate the long term forecast. This will
bring the typical summer pattern of morning clouds, afternoon sun,
and warm temps, with temps rising into the 90s across the interior
late next week. The main forecast challenge continues to be the
timing and strength of weak shortwaves that could help deepen the
marine layer. Made a few cosmetic changes to the forecast based on
recent model runs. Otherwise, previous forecast remains in good
shape. /64
&&

.AVIATION...VFR across the board at this hour but the north coast
may see a stratus deck return at around 020 and with some light
drizzle per Langley radar within the next couple hours. The
central Oregon coast will hold off a little longer and may not
pick up the drizzle either. MVFR cigs should push partially
inland overnight. Think there is a good chance that the northern
interior TAF sites, including KPDX, KTTD, and KHIO, see MVFR
develop between 12Z-18Z Sat. VFR is more likely over the central
and southern Willamette Valley.

KPDX AND APPROACHES...Mainly VFR conditions through tonight, with
a 4-5 kft cig this afternoon scattering out this evening. There is
a good chance that MVFR cigs push back in between 12Z and 18Z Sat.
Pyle/JBonk

&&

.MARINE...No changes...previous discussion follows. A typical
summer- time pattern is beginning to set up today, with high pres
settling over the NE Pac and a thermal trough over N Calif. This
pattern will become better defined on Sat and remain in place
through most of next week. This will bring gusty northerly winds
over the waters, particularly during the afternoon and evening
hours. Have issued a small craft advisory for winds for the
central OR waters from mid afternoon Sat through Sun evening, with
gusts to 25 kt expected. We will likely need small craft
advisories for winds through the weekend and much of next week.
The strongest winds will be south of Cascade Head, but gusts to 25
kt are also expected over the northern waters at times as well.

Seas will remain below 5 ft through Sat. However, the increasing
northerly winds will create choppy short-period seas starting Sun
and continuing through much of next week. Seas may push into the
7-9 ft range at times and may require advisories for hazardous
seas as periods are expected to be in the 7 to 9 sec range. Pyle

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory for winds from 3 PM Saturday to 2 AM PDT
     Sunday for Coastal Waters from Cascade Head OR to Florence
     OR out 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.



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