796
FXUS66 KPQR 111811 AAA
AFDPQR

Area Forecast Discussion...Updated
National Weather Service Portland OR
1111 AM PDT Sat May 11 2024

Updated Aviation...

.SYNOPSIS...A ridge of high pressure will remain overhead
today, bringing another day of unseasonably warm temperatures to
the area. Inland valley temperatures are expected to reach the
upper 80s to low 90s today. Saturday night into Sunday, winds
throughout will shift to onshore flow as a shortwave trough
moves over the region, bringing cool yet still above seasonal
normal temperatures into early next week.

&&

.SHORT TERM...Now through Monday... The positively tilted ridge
axis remains directly overhead but will slip southward through
the day as a trough moves eastward across the northeast
Pacific. The thermal trough has shifted inland toward the
Willamette Valley and will continue towards the Cascades this
afternoon. This has allowed the surface high to shift winds
along the coast from offshore to onshore. Hi-res models have
stratus developing along the coast this morning and observation
sites near Tillamook support this development. This will
moderate temperatures this afternoon. Temperatures along the
coast will be 8-10 degrees cooler than yesterday, peaking in the
upper 60s to low 70s. The Willamette Valley will see another
toasty day in the mid to upper 80s. Chances are high (70-90%)
that temps peak at or above 85 degrees but are much lower than
Friday to reach 90, peaking at 20-40% only around the
Portland/Vancouver metro. Widespread cooling is expected Sunday
as the upper- level shortwave trough moves towards the coast,
weakening the ridge overhead and pushing it eastward. Sunday
highs peak around 60 along the coast an in the upper 70s to near
80 in the interior valleys. Monday will see the shortwave come
onshore across the PNW which will drop temperatures even
further as northerly onshore flow increases. Highs along the
coast will remain near 60 while interior valleys only peak near
70.

With such unseasonably warm temperatures for early Spring and
coming out of cold weather, there is no doubt people will visit
rivers, lakes, and the ocean for SW Washington and NW Oregon
this weekend. It is important to remember that rivers and lakes
remain dangerously cold with water temperatures mainly in the
40s. Such temperatures can easily cause cold water shock for
those without proper cold water gear, resulting in an
involuntary gasp of air that can lead to drowning. Be sure to
bring a life vest and be extremely cautious around rivers,
especially with snowmelt causing cold and swift currents!
-Batz/JH

.LONG TERM...Tuesday through Friday...WPC cluster analysis has
moved more towards a solution favoring ridging re-developing by
the middle of next week. Nearly all ensemble members display
relatively strong and broad ridging by Wednesday next week,
allowing temperatures to climb to the upper 70s in the latter
half of the week. Agreement lessens into Friday as there is a
10-20% chance of a trough developing and pushing south into the
region. This trough would bring more seasonable temperatures
and light rain showers back to the area, but there is still not
enough model convergence to be certain. Cluster analysis trends
farther toward a trough developing into early next weekend.
-JH/Batz

&&

.AVIATION...High pressure continues to promote clear skies VFR
conditions across most of the region, with the exception of a
narrow band of low stratus continuing to hug the Oregon coast as
of 18z Sat. Visible satellite does show stratus eroding from the
coastal communities and retreating back towards the beaches,
leaving VFR conditions from KAST to KTMK. However, latest guidance
suggests stratus may continue to hinder KONP with intermittent
IFR/LIFR through much of the day. Expect stratus to redevelop and
push back into coastal communities later this evening, bringing
IFR back to KAST 03-06z Sun. Status will likely intrude farther
into the coast range valleys tonight as onshore flow begins to
increase, but the marine layer will remain too shallow to reach
into most inland locations during the period. Probabilistic
guidance does show a 20-30 percent chance for IFR stratus to make
it as far as KKLS in the north and KEUG in the south after 12z
Sun. Otherwise, expect clear sky VFR to prevail through the period
at all inland sites, with winds picking up to 8-10 kt out of the
NW this afternoon as onshore flow increases a bit.

PDX AND APPROACHES...Unrestricted VFR through the period as high
pressure continues to promote clear skies. Winds increasing to
8-10 kt out of the NW 21z Sat to 04z Sun as onshore flow picks up
a bit. /CB

&&

.MARINE...High pressure still anchored well offshore. Thermal
trough is just inland, and will continue moving farther inland
today. Will maintain north to northwest winds on the water today
into tonight. Gradients tighten just a tad, enough such to get
winds gusting 20 to 25 kt at times this afternoon into this
evening. As such, have put up Small Craft Advisory for that time.
Seas mostly 5 to 7 ft.

Little change for Sunday into early next week, as high pressure
remains anchored well offshore, and lower pressure well inland. As
such, will maintain north to northwest winds on the coastal
waters. Could see gusts 20 to 25 kt at times in afternoons and
evenings. Seas remain mostly at 5 to 7 ft.

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 1 AM PDT Sunday
     for PZZ251>253-271>273.
&&

$$

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