420 
FXUS66 KPQR 101711 AAA
AFDPQR

Area Forecast Discussion...Updated
National Weather Service Portland OR 
1010 AM PDT Mon Aug 10 2020

Updated Aviation Discussion

.SYNOPSIS...Another warm and breezy day on tap for the region. But,
onshore flow will increase later today into tonight, bringing cooler
marine air into the interior for Tuesday through Thursday. High
pressure will build towards the weekend, with a warming trend.
&&

.SHORT TERM...Today through Wednesday...High pressure over the region
continues. Not a lot of change with the overall air mass across the
region to start the day. Various models still show a few deg warmer
today as compared to Sunday, as suggested by the 850 mb temps. Last
several model runs continue to show a lowering of 500 mb heights and
increasing onshore flow later today. This would tend to slow the
heating this afternoon, with temperatures being down a few. Now,
final consideration is the temperatures this am, as compared to this
time on Sunday. At 2 am, most of the interior temperatures are 
running about 4 to 7 deg higher today. So, given all factors, should 
see temperatures this afternoon about 2 to 4 deg warmer than those 
seen on Sunday in the north interior, and 4 to 6 deg higher area 
areas to east and south of Salem.

Onshore gradients will again tighten today, with breezy northerly
winds expected once again. As the onshore flow begins to increase,
will see breezy northwesterly winds toward evening.   

Low clouds have been pushing southward along the Washington coast,
and will push into the coastal areas as far south as Seaside this am,
with clouds remaining just offshore on to the south. These clouds
will break up today. But, these clouds will reform this evening along
the coast, and spread into the coast mtns valleys. As the low level
onshore flow increase, these clouds will push inland, with most of
the clouds pushing up the Columbia River. Do think will have plenty
of clouds along the coast, into the Coast mtns, and a good part of
the interior to north of Salem for Tuesday morning. These clouds will
gradually dissipate over the interior around midday, but persist
longer along the coast.

Will be cooler on Tuesday, with temperatures in the 60s along the
coast, and mostly mid to upper 70s inland, and around 80 for a few
areas, such as Hood River Valley and far south Willamette Valley. In
addition, expect to see breezy westerly winds over the high Cascades
and through the central Columbia Gorge, where winds may gust up to 30
mph at times. 

Rather pleasant day on tap for Wednesday, as Wednesday looks to be a
repeat of Tuesday, but with somewhat less inland coverage of clouds. 
/Rockey

.LONG TERM...Thursday through Sunday...Models and their ensembles
show good agreement now that the upper trough responsible for the
midweek cooldown will push east of the Rockies by Friday. Trailing
weak shortwave energy may keep some clouds around Thursday night and
Friday, but long range models are clearly signaling a warming trend
Friday through the upcoming weekend as some form of upper ridging
amplifies over the western United States. This will likely result in
weaker onshore flow, a shallower marine layer, and a warmer air mass.
With the ECMWF ensemble mean 850 mb temperature warming to around +20
deg, inland high temperatures in the 90s are certainly possible by
Sunday. NBM guidance also reflects this, so we largely leaned on the
NBM for the forecast next weekend.  Weagle

&&

.AVIATION...VFR conditions for inland locations for today, with 
intermittent MVFR/IFR conditions along the coast with 
improvement towards VFR expected after 20Z Monday. Gusty winds 
this afternoon, especially along the coast. 

IFR to low MVFR cigs return to the coast this evening and push 
into the coast range valleys tonight and up lower Columbia River 
to near KSPB. These lower cigs could possibly reach KPDX after 
12Z Tuesday but, confidence is currently low.

KPDX and APPROACHES...VFR continues next 24 hours with gusty
northerly winds for several hours after 00Z Tue. Low MVFR cigs
approach KPDX near 12Z Tuesday but, confidence is currently low.
/42

&&

.MARINE...A ridge of high pressure extending onto the Washington 
coast and a trough of low pressure along the south Oregon coast will 
bring gusty north winds to the coastal waters today and tonight. The
strongest winds are expected generally south of Tillamook Head 
where gusts of 25 to 30 kt are possible. Seas will build to 8 to 
10 ft with the strong winds, and be dominated by steep short 
period swells and wind waves. As the ridge of high pressure 
shifts south tonight and Tuesday, the winds will ease, leaving 
northwest winds under 20 kt to persist through most of the week.
A northwest fresh swell arriving tonight will temporarily drive 
seas back to 8 to 10 ft Tuesday before subsiding again. /mh

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 6 AM PDT Tuesday for coastal waters 
     from Cape Shoalwater WA to Florence OR from 10 to 60 NM.

     Small Craft Advisory until 5 PM PDT this afternoon for Coastal 
     waters from Cape Shoalwater WA to Cascade Head OR out 10 
     NM.

     Small Craft Advisory until 11 PM PDT this evening for Coastal 
     waters from Cascade Head to Florence OR out 10 NM.

&&

$$

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