503 
FXUS66 KPQR 100605
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR 
1104 PM PDT Sat Mar 9 2024

.SYNOPSIS...
A series of Pacific fronts will push across the region through 
Tuesday. First front has passed through and expecting another 
late tonight/Sunday morning, bringing breezy south winds through
early Sunday morning. Will see a few thunderstorms through this
evening, as well as Sunday afternoon/evening. Will see dry 
weather with warmer temperatures near the end of the week as a 
strong ridge aloft builds across the region.

&&

.DISCUSSION...TONIGHT THROUGH FRIDAY NIGHT...Currently, post-frontal 
showers through the region moving northeast through the 
northern coast and central Willamette Valley. Isolated
thunderstorms were observed in Astoria early this afternoon. 
Otherwise, brief light to moderate showers and locally gusty 
winds (30 to 40 mph). 

A weak ridge shifting inland continues to scour out the
remaining post-frontal showers, with a quick-moving front 
following behind, expected to arrive tonight. The coast will
have quickly returning rain near midnight, arriving inland 
early Saturday morning, and in the Cascades late Saturday
morning. Pressure gradients will tighten overnight, resulting in
a period of gusty southerly winds across all of northwest OR and
southwest WA, strongest at the coast.

For coastal communities, wind gusts up to 40-55 mph are 
expected, with chances to exceed 55 mph around 60-70%. Inland 
coastal communities such as Tillamook and Astoria will see gusts
up to 35-50 mph, strongest at Tillamook. As for open beaches 
and coastal headlands, expecting 50-60 mph wind gusts dropping 
off around sunrise. When it comes to the Willamette Valley and
Cowlitz Valley, there is only a 30-40% chance of wind gusts 
exceeding 40 mph inland overnight. Instead, wind gusts will most
likely peak between 25-35 mph for inland locations. While winds
of this magnitude do not warrant a Wind Advisory, it is still a
good idea to secure garbage cans and other loose outdoor
objects. However, impacts will be more noticeable at the coast
where downed trees and power outages possible, at least near
beaches and headlands.

For this quick-moving front, rainfall accumulation through 
Sunday evening is as follows. 1.0 to 1.25 inches of rain is 
expected along the coast, with chances of exceeding 1.25 inches
around 30-40%. For the interior, 0.25 to 0.50 inches of rain, 
with chances of exceeding 0.50 inches around 30-40%. For the 
Coast Range and Cascades, 1.25 to 1.75 inches of rain, with 
chances of exceeding 1.75 inches around 30-40%. Fortunately,
these rain amounts are not high enough to suggest river flooding
will occur, so minimal hydro impacts are expected.

For snow, will maintain current Winter Weather Advisories for 
areas above 3500 ft in the south Washington Cascades, and above 
4000/4500 ft for north Oregon Cascades as far south as Santiam 
Pass. While snow will not be all that heavy, will be enough to 
maintain snow-covered roads. New snow across the higher Cascades
from today through Sunday afternoon looks to be in 5 to 10 inch
range for areas 2500 to near 4000 feet, but 10 to 15 inches for
areas above 4000/4500 ft. Bulk of that will fall tonight into 
Sunday. 

Occasional thunderstorms will return Sunday afternoon/evening,
with continued light showers into Monday just before the next 
front arrives Monday evening. Rain on Monday evening will 
quickly transition to showers overnight and persist through
early Wednesday morning. As a result, more snow for the 
Cascades, with another 8 to 12 inches of snow expected for 
Monday afternoon through Tuesday evening. 

Wednesday morning, a strong ridge aloft builds across the 
region, with the WPC cluster analysis in good agreement about
this pattern. Offshore winds will return as the ridge will
persist through the weekend. The NBM has an 80-90% chance of 
temperatures reaching 65 degrees F by next Friday for much of 
the I-5 corridor, and a 30-40% chance of temperatures reaching 
70 degrees. On average, the first 70 deg of the year occurs in 
early April across the interior. With that warmer weather, will 
see the snow across the lower elevations (below 2000 ft) 
gradually melting. Rivers will be on the rise, but no flooding 
is expected.  -JH/CR

&&

.AVIATION...Cold front approaching coast with rain and windy
conditions ahead of the front. Cold front to coast 10-12Z Sun,
then weakening as it moves to inland. Front moves to the interior
valley around 11-14Z. Will see wind increase for the inland 
valleys with south to southwesterly wind gusts 20-30 kt ahead and
behind the front. Winds ease after 23Z Sun to 03Z Mon. Flight
conditions generally lowering to MVFR with spotty IFR possible at
the coast as the front moves through. 

*Note: The observations out of KONP are generally limited to wind
 and pressure at this time. Periodically cloud cover, vis, and
 present wx are reported but are unreliable.

PDX AND APPROACHES...VFR lowering to MVFR with cigs between 2000
and 3000 feet after 12Z Sun. MVFR prevailing through early
afternoon then chances for MVFR decreasing after 21-23Z. South to
southwest winds 20-30 kt as the front approaches and moves 
through later tonight. /mh

&&

.MARINE...Observations at buoy 46050 as of 3 PM PST show southerly
winds gusting to 35 kt with steep and choppy seas around 13 ft at
8 seconds. Buoy 46243 also shows 13 ft at 9-10 seconds. Based on 
these observations, (albeit they're the only few reliable buoy 
obs in our outer waters), the current Gale and Hazardous Seas 
Warnings are verifying. 

Another frontal system is expected to impact the waters tonight 
into early Sunday morning, returning strong winds and building
seas. There is high confidence (greater than 90% chance) of Gale
force gusts greater than 40 kt across the waters. There is also a
60-80% chance of frequent storm force gusts up to 50-55 kt in the
outer waters, with the strongest winds between 7 PM Saturday to 1
AM Sunday. Therefore, the Storm Warning for outer water zones
PZZ271-273 remains on track through early Sunday morning. There
also about a 50/50 chance the inner waters will see gusts to 
50-55 kt, but they will be more isolated and sporadic to support a
Storm Warning. Therefore, the Gale Warning for inner water zones
PZZ251-253 remains in effect through early Sunday morning. 

Seas will also build close to 20 ft tonight, peaking around 20-22
ft in the outer waters and 18-20 ft in the inner waters. After 5 
AM PDT Sunday (note Daylight Saving Time begins 2 AM Sunday), the 
front will move inland and wind speeds will gradually weaken.
However, a long period westerly swell will begin moving through
the waters. Therefore, seas will remain elevated in the mid to 
upper teens (15-17 ft) through early next week. A Hazardous Seas 
Warning has been issued following the Storm/Gale Warnings beginning
early Sunday morning and lasting through at least early Monday 
morning.						       
-Alviz/Weagle

&&

.BEACH HAZARDS...Minor tidal overflow is forecast for the south
Washington coast around late morning to early afternoon Sunday.
Minor flooding, up to one foot above ground level during high
tides is expected in low lying areas near bays, sloughs, and the
lower reaches of the coastal rivers. The Toke Point gauge is
expected to reach 11.2 ft at high tide 2 PM PDT Sunday. Tidal
observations from today (Saturday) matched our forecast, so we
expect tomorrow's Coastal Flood Advisory for the south Washington
County to remain on track.					     
  -Alviz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...High Wind Warning until 5 AM PST Sunday for ORZ101>103-106-107.

     Winter Weather Advisory until 5 AM PST Monday for ORZ126-127.

WA...High Wind Warning until 5 AM PST Sunday for WAZ201-203.

     Winter Weather Advisory until 5 AM PST Monday for WAZ211.

     Coastal Flood Advisory from noon to 4 PM PST Sunday for WAZ201.

PZ...Gale Warning until 8 AM PST Sunday for PZZ210-251>253.

     Hazardous Seas Warning from 8 AM Sunday to 5 AM PST Monday for 
     PZZ210-251>253-271>273.

     Storm Warning until 8 AM PST Sunday for PZZ271>273.
&&


&&

.BEACH HAZARDS...Minor tidal overflow is forecast for the south
Washington coast around late morning to early afternoon Sunday.
Minor flooding, up to one foot above ground level during high
tides is expected in low lying areas near bays, sloughs, and the
lower reaches of the coastal rivers. The Toke Point gauge is
expected to reach 11.2 ft at high tide 2 PM PDT Sunday. Tidal
observations from today (Saturday) matched our forecast, so we
expect tomorrow's Coastal Flood Advisory for the south Washington
County to remain on track.					     
  -Alviz

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...High Wind Warning from 10 PM this evening to 5 AM PST Sunday for

     ORZ101>103-106-107.

     Winter Weather Advisory until 5 AM PST Monday for ORZ126-127.

WA...High Wind Warning from 10 PM this evening to 5 AM PST Sunday for

     WAZ201-203.

     Winter Weather Advisory until 5 AM PST Monday for WAZ211.

     Coastal Flood Advisory from noon to 4 PM PST Sunday for WAZ201.

PZ...Small Craft Advisory until 4 PM PST this afternoon for PZZ210.

     Gale Warning until 8 AM PST Sunday for PZZ210-251>253.

     Hazardous Seas Warning from 8 AM Sunday to 5 AM PST Monday for 
     PZZ210-251>253-271>273.

     Hazardous Seas Warning until 4 PM PST this afternoon for 
     PZZ251>253.

     Gale Warning until 4 PM PST this afternoon for PZZ271>273.

     Storm Warning until 8 AM PST Sunday for PZZ271>273.

&&

$$

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