648
FXUS66 KPQR 140957
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
254 AM PDT Fri Jun 14 2024

.SYNOPSIS...
A bit cooler today, as weakening front arrives. Unsettled weather for
the weekend, with onshore flow, clouds and even showers. High
pressure rebuilds offshore early next week, with dry and mild weather
returning towards middle of next week.

Key Messages...

-  Cooler, with increasing clouds today. Chance of showers
   along the coast (Tillamook northward) and west Washington.

-  Showers Saturday through Monday. A small chance (15-25%)
   of afternoon/evening thunderstorms on Sat and maybe Sun.

-  High pressure builds next week, bringing dry and warm
   conditions back to the region later next week.

&&

.SHORT TERM...Now through Sunday...
Today is a transition day, with increasing onshore flow. This will
result in cooler temperatures today, along with breezy westerly winds
over the high terrain, as well as through the Columbia Gorge. A weak
front offshore push onshore today, but not much in way of any
precipitation, aside from a few showers along the coast.

Broad upper trough offshore and over the Gulf of Alaska will push
into  the Pac NW Fri night and Sat. As such, will see bit cooler air
aloft, with showers increasing. But, overall, precipitation amounts
not all that impressive, with most areas getting 0.10 inch or less.
Given potential of breaks in the clouds on Sat, could see a few
`beefier` showers, with potential of bit more rain. Add to that, may
get enough instability to support a few thunderstorms. Will maintain
current forecasts, with little change.

More clouds around the region on Sat, than to continued moderate to
strong onshore flow. Still, will maintain high chance of showers as
upper level disturbance in the westerly flow shifts inland and over
the inland Pac NW. Will keep small (15-25%) chance of thunderstorms,
but bit question will be whether or not will get enough breaks in
the clouds to boost low level warming, and hence any steepening of
lapse rates. With more warming, better the chance of a few
thunderstorms, while less sun breaks and thus less warming, the
lower the potential for thunderstorms. Based on current trends, any
thunderstorms likely to remain rather isolated at best on Sat.
Showers decreasing Sat night.

Sunday remains to be challenging forecast. Some models still have
somewhat unstable air mass over the region, supporting showers. But,
more recent runs of GFS and NAM models indicate decent potential of
showers, given upper trough shifting overhead. But, does seem this
potential decreasing through the day, given main upper support is
swinging east of the Cascades. WIll make no big changes in forecasts,
but if trends continue, Sunday could be more dry than current
expected. But, still plenty of clouds and coolish.

.LONG TERM...(Monday through Thursday)...Still have upper trough over
the region on Monday, with continued showers. By Tuesday, most models
(GFS, UKMET and ECMWF) show upper trough shifting well east of the
Cascades. So, shower potential will end in the afternoon for most all
areas except the Cascades. High pressure offshore will build again
for middle of next week, bringing return of dry weather. Overall air
mass will gradually warm again, with return of bit warmer than normal
temperatures. Will trend to 60s along the coast, and 70s inland.

&&

.AVIATION...Inland terminals are all seeing clear sky VFR
conditions, while the coast is seeing intermittent low marine
cloud cover ahead of a weak front arriving around 15-16z Thu,
reducing conditions to MVFR at times at coastal terminals. Threat
of MVFR conditions at the coast should end by around 19-20z Fri,
after which VFR conditions should stay locked in for the rest of
Friday. Winds are fairly light and variable at all terminals, with
winds generally under 6 kt. Slightly stronger southerly winds
pick up with the frontal passage, up to maybe 10-15 kt at times.

The front reaches inland around 20z or so, creating a low end VFR
deck. Chance for MVFR ceilings has decreased to under 10%, and
impacts looks to be minimal other than maybe a few light showers.
Winds gradually shift westerly and weaken after the frontal
passage ends.

PDX AND APPROACHES...VFR under clear skies. Northwesterly winds
are currently under 8 kts. A weak front reaches the area around
20z, possibly bringing some weak showers and slightly stronger
southerly winds up to 10 kt, but chances are under 10% of MVFR
ceilings. Expect a low end VFR broken deck to develop at that
time. Winds will shift westerly and weaken after the front passes.
/JLiu

&&

.MARINE...Small Craft Advisory has ended for all waters, and winds
are currently near zero. Seas are currently around 5-7 ft at 11
seconds, and swells should not change much over the next few days.
A weak front will bring some slightly stronger southerly winds
Friday morning, and will be followed by a stronger front around
midnight Friday night. This marks a return to relatively
stronger, westerly winds across all waters. Seas will be slightly
elevated Saturday due to this front, rising to 5 to 7 ft on
Sunday, before subsiding again towards 4 to 6 ft by the start of
the upcoming week.    /42/JLiu

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...None.

&&

$$

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