FXUS66 KPQR 100329 AAA

AFDPQR



Area Forecast Discussion

National Weather Service Portland OR

828 PM PDT Fri May 9 2025



Updated Aviation discussion



.SYNOPSIS...Benign weather conditions through the end of the 

week with daytime highs in the 60s-70s through the weekend and

into next week. Today is expected to be the warmest, but as a

broad area of low pressure starts to push eastward, temperatures

are expect to slowly cool towards the 50s along the coast and

60s for inland locations. Wetter weather is also expected to

make a return on Sunday into early next week.



&&



.SHORT TERM...Today through Sunday Night...Dry and warm today with

mostly clear skies as ridging continues to build into the area.

Temperatures this afternoon peaking in the mid to upper 70s in the

inland lowlands, closer to low 60s at the coast. Temps slightly

elevated in the Portland metro area due to heat island effect. Winds

will be westerly shifting NNW for most areas. Top gusts this

afternoon will max out around 10-15 mph. These winds decrease doing

into the evening, with light and variable winds throughout tonight.



Cloud cover begins to increase tonight going into Saturday as the

leading edge of the next incoming low begins to move in. Temperatures

will be much more moderate on Saturday, with inland areas seeing a

high around 70 and the coast seeing a high in the low to mid 50s.

Rainfall begins Saturday night, though the bulk of the rain is

expected to fall during Sunday daytime hours. Between 5am Sun and 5am

Mon, there is only around a 20-40% chance of exceeding 0.25 inches of

rainfall in the Willamette Valley and SW Washington lowlands. At the

coast and over elevated terrain (Willapa Hills, Coast Range,

Cascades), this chance is closer to 50-70%. From early Sunday morning

onwards, winds switch southwesterly, with gusts up to 15-25 mph

possible. Also of note, with upper air temperatures will be cooler

with Sunday's system, can't rule out some isolated weak

thunderstorms. CAPE values right around 100 J/kg, with NBM putting a

10% chance of thunderstorms Sunday afternoon. /JLiu



.LONG TERM...Monday through Thursday...Moisture continues into

Monday, with continued showers until Monday evening. Once again

around a 10-15% chance of some isolated thunderstorms Monday

afternoon near the tail end of the system due to moderate instability

aloft. However, this will be heavily dependent on whether or not

sufficient clearing in cloud cover occurs as well as the path of the

incoming low. If the low moves more northward towards our CWA, the

probability of thunderstorms will increase, while if the low tracks

more towards the OR/CA border the probability will be lower. Showery

conditions with light precipitation remain in the forecast through

Friday as WPC 500mb Cluster guidance shows strong agreement in

troughing continuing through at least Thursday. /42/JLiu



&&



.AVIATION...Southwest flow aloft increases tonight into Saturday

along with increasing mid/high clouds. Conditions remain

predominately VFR across the area, except at the coast where

marine stratus is likely to push onshore around 10-12z Saturday.

Expect a southerly wind reversal to bring MVFR stratus to the

coast through Saturday morning, with the highest probabilties 

along the central Oregon coast. 



PDX AND APPROACHES...VFR with increasing mid/high clouds through

Saturday. Predominately northwest winds 4-6 kt become light and

variable after 12z Saturday. /DH



&&



.MARINE...High pressure will maintain steady conditions through at

least Sunday. Seas will be 5-7 ft at 10 seconds. Winds will be

northerly 5-10 kt through Saturday morning before transitioning to

the south in the evening as a low pressure system moves towards

the northeast Pacific. On Sunday, winds will be 10-20 kt with 

gusts up to 25 kt, mainly from Cape Falcon to Florence. A small

craft advisory may be needed but given the marginal conditions,

will hold off for now. 



The next pattern shift occurs on Monday. A strengthening low

pressure system will move over the coastal waters causing winds

and seas to increase. There is still a lot of inconsistency in

modeled location of the low. However, with the colder air filling

in behind the low, cannot rule out a few thunderstorms embedded 

within the precipitation. -Batz/Muessle



&&



.PQR WATCHES/WARNINGS/ADVISORIES...



OR...None.

WA...None.

PZ...None.



&&



$$



www.weather.gov/portland



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