The Summit at Snoqualmie

000
FXUS66 KSEW 312019
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
119 PM PDT Sat Oct 31 2026

.SYNOPSIS...
Drier conditions will settle into the region into Monday as an
upper low moves south and a ridge builds into the region. The 
first half of next week will remain mostly dry, with chances of 
precipitation increasing mid to late week as a series of systems
approaches the Pacific Northwest.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
An upper level low will continue to weaken today as it moves 
onshore to the south, with split flow briefly developing aloft
over western Washington. This will allow conditions to dry out 
this evening as an upper level ridge builds in overhead. While 
cloudy skies will stick around, some sun breaks will help bring 
high temperatures back to seasonal normals generally in the low 
to mid 50s. Cool overnight lows in the 30s will bring areas of 
additional frost development to the area on Sunday morning while
moisture in the low levels promotes another round of morning 
fog. High pressure building into the Pacific Northwest will 
maintain dry conditions and seasonable temperatures through 
Monday, with periods of morning fog and afternoon sun breaks. As
the upper level ridge axis shifts eastward on Monday, ensembles
continue to show low chances of rain generally along the coast 
and over the Olympic Peninsula.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Chances for light rain continue into Tuesday as a splitting
frontal system passes over the region. Wetter and more unsettled
conditions are expected to return on Wednesday and beyond as a
series of systems are set to move over the region. While
ensembles continue to show a fair amount of variability heading
into next weekend, the system Friday looks to be the strongest
and will likely bring breezy winds alongside widespread lowland
rain and mountain snow.

15

&&

.AVIATION...
Widespread VFR conditions this afternoon. Fog is expected to 
develop late tonight into Sunday morning, leading to another 
round of IFR/LIFR conditions with highest chances for terminals 
south of PAE. Improvement to VFR expected after 18Z. Northerly 
surface winds 4-6 kt becoming light and variable tonight into 
Sunday morning. 

KSEA...VFR conditions today. Conditions will deteriorate Sunday 
morning with LIFR fog expected to form at the terminal after 10Z-
12Z. Conditions will improve to VFR after 18Z. NW winds this 
afternoon 5-6 kt, becoming NE this evening around 3-5 kt. 

29

&&

.MARINE...
Shower activity was decreased this afternoon across the coastal 
waters and the threat for brief waterspouts has ended. 

A surface low pressure will continue to dig south today. High 
pressure will build over the waters tomorrow through Monday. A 
system will approach the coastal waters to the north, leading to an 
increase in winds over the outer coastal waters on Monday. Latest 
guidance suggests there is a 55-70% chance for wind gusts briefly 
exceeding 21 kt Monday morning over zones PZZ170 and PZZ173. High 
pressure will move inland on Tuesday. The next system arrives 
Wednesday. Winds will increase across the coastal waters; however, 
latest probabilities indicate a 40-50% chance for wind gusts meeting 
small craft thresholds. A stronger system will impact the waters 
Thursday into Friday, bringing stronger winds across the coastal 
waters and interior waters, with latest probabilities at 65-75% for 
winds above 21 kt. 

Seas 4-6 feet this afternoon, decreasing below 5 feet tonight. Seas 
will build on Monday 7-10 feet and will hover around this range 
through late in the week. With the stronger system arriving Friday, 
latest guidance suggests seas will build  up to 13-16 feet. 

29

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.

&&

$$