041
FXUS66 KPQR 190937
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
235 AM PDT Fri Jul 19 2024

.SYNOPSIS...Above-average temperatures continue as high pressure
strengthens through Saturday. Chance of light showers, mainly along
the coast late Sat night to Sunday morning. Then, upper level
troughing brings cooling trend early next week, with temperatures
closer to seasonable normals.

&&

.SHORT TERM...Today through Sunday...Water vapor satellite imagery
shows weak upper level shortwave troughing sliding northeastward
over the Pacific NW this morning. Should continue to deepen the
marine layer along the coast. Heights rebuild over the region this
afternoon, so expect temperatures to warm again to around 90 degrees
for the interior lowlands. The upper level ridge will amplify over
the region on Saturday while 850 mb temperatures warm to around 22-
24 deg C. Inland highs are expected to reach the mid 90s (60-80%
probability), while highs near Hood River will push triple digits
(50-60% probability). This may lead to localized areas of major
HeatRisk from the Portland metro through the Columbia River Gorge.

Upper level ridge begins to shift eastward on Sunday. Models are
showing better agreement of a negatively tilted shortwave trough
lifting north over the coastal waters Sat night into Sunday morning,
albeit rather weak. Bumped up chances for showers across the area
(best chances along the coast), but have held off on mentioning
thunder as both NBM and SREF probabilities max out around 10%. That
said, elevated convection still possible so will need to continue to
monitor the situation. Temperatures Sunday afternoon expected to be
around 10 degrees cooler than Saturday, along with stronger onshore
winds.  /DH

&&

.LONG TERM...Monday through Thursday...Temperatures are very likely
to trend cooler near seasonable normals early next week. Upper level
troughing nudges into the Pacific NW on Monday with strong onshore
flow. Marine stratus more likely to push inland Monday morning with
highs topping out around 80 degrees. WPC cluster analysis remains in
good agreement with model ensembles showing upper level low centered
near Haida Gwaii on Tuesday, slowly shifting east into British
Columbia by mid-week. NBM guidance suggests temps will likely trend
closer to the mid-80s as near seasonal normals and dry weather
persists next week. /DH

&&

.AVIATION...High pressure remains over the region, along with
mild southwest flow aloft, will maintain VFR under clear skies.

Onshore low level flow will maintain moist air mass on the coast
into the Coast Range valleys, with widespread IFR marine stratus,
which will continue to obscure terrain below 1500 ft this am.
Pockets of IFR stratus also will be in Cowlitz Valley and Lower
Columbia River Valley as far inland as Ridgefield across to
southeastern Clark County until 17Z. Stratus will burn back to
the beaches by late morning, but will surge back onshore after
sunset.

PDX AND APPROACHES...Little change, with clear skies under high
pressure and mild southwest flow aloft. Like past few days, areas
of IFR stratus expected across Clark County down to around KTTD
from 12Z to 16Z, but should stay too far north to affect KPDX.
But, will be close. For now, will just have SCT IFR clouds for
KPDX with coming 12Z TAF.                             /Rockey

&&

.MARINE...High pressure offshore will gradually strengthen today
into this weekend, and with thermal low pressure on south Oregon
coast, will see return of north winds on the waters. As pressure
gradients tighten on Saturday, will see gusts to 25 kt at for Sat
and Sun, mainly in the afternoons/evenings from Cascade Head
southward. Seas mostly stay in the 3 to 5 ft range, with a mix of
variable period swell, but with gusty winds, will have locally
choppy steep seas to 6 or 7 ft. Again, this mainly for areas south
of Newport.                                          /Rockey

&&

$$

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