Sunrise 5:29 AM   Sunset 8:42 PM Moonrise 6:11 PM   Moonset 3:17 AM

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FXUS66 KPQR 220434 AFDPQR

Area Forecast Discussion...Updated Aviation National Weather Service Portland OR 934 PM PDT Tue May 21 2024

SYNOPSIS
Slow moving front continues to move southeast, gradually blanketing the region with widespread rain. Rain will become scattered showers tonight into Wednesday. Dry and warmer Thursday before becoming unsettled for Friday into the weekend.

SHORT TERM
Tuesday afternoon through Thursday...Satellite imagery around 2 PM Tuesday, front slowly moves southeast bringing widespread rain through most of the region (North of Eugene and Newport). With this front bringing northwesterly winds at the surface, lowlands and south areas of the region are expected to receive less rain due to the rain shadow effect.
Rain will turn showery this evening, then isolated overnight for areas west of the Cascades.

Behind this front, a closed low moving south southeast through western British Columbia will reach western Washington around 5 AM Wednesday. This low will then drift southeast into northeast Oregon through the rest of Wednesday. The core of this low will just miss our region, resulting in showers, similar to today.
With northwesterly winds and the closed low coming from the north, precipitation along the Coast Range will be limited, with majority of the precipitation along the Cascades. Through Wednesday evening, chances to exceed 0.5 in of precipitation over 24 hours is 10-30% chance for the valley lowlands and 50-70% for coastal areas north of Tillamook. With the aforementioned low just missing our region, instability will be rather limited, therefore thunderstorm chances will be low across the Cascade foothills. The high Cascades will receive snow but snow levels will remain well above mountain passes.

Thursday, a weak shortwave ridge builds over the region as the closed low moves east over the northern Rockies. This will bring sunny skies and warm temperatures up into the upper 60s (20-30% to exceed 70) for the interior lowlands and mid 50s/upper 50s along the coast.
-JH

LONG TERM
Friday through Monday...An unsettled weather pattern is expected to continue through at least Saturday.
WPC's 500 mb cluster analysis indicates a week shortwave could bring light showers Friday followed by an upper level low bringing slightly more showers to the region Saturday. Timing and amount of precipitation continues to remain uncertain, though temperatures are expected to be near seasonal normals.

The pattern becomes a bit more uncertain Sunday on whether troughing will still be present to continue showers. By Monday, dry conditions are expected, with 20% of clusters suggesting a weak trough approaching and 80% of clusters suggesting a ridge overhead or nearby (location and timing still uncertain). This brings significant uncertainty in temperatures with NBM 25th to 75th percentiles for inland valleys ranging anywhere from upper 60s to low 80s.
-JH

AVIATION
The front has passed, and we slowly transition into a post-frontal environment for the rest of Tuesday night. Continued showers at the coast will keep conditions there MVFR or lower at least until 10z Wed. The northern coast (KAST) continues to see MVFR conditions, while the southern coast (KONP) sees LIFR conditions. Ceilings slowly begin to rise around 10z Wed, but this will be a gradual process, with periods of lowered cigs still possible (40-60%) for the rest of the period.

Further inland, northern terminals in the Willamette Valley have already mostly transitioned to VFR conditions, and will likely remain that way for the rest of the TAF period. The southern Willamette Valley continues to see some showers intermittently lowering cigs to MVFR, but these end by 10-12z Wed, after which VFR conditions dominate (90% confidence).

Winds are also expected to begin to increase after sunrise on Wed, with stronger gusts up to 25 kt possible at all terminals from the west. KAST will be the exception, and could see slightly stronger gusts up to 30 kt.

PDX AND APPROACHES...The front has passed through the area, and VFR conditions are expected to dominate through the rest of the TAF period with 90% confidence. Winds will pick up after around 18z Wed from the west, with gusts up to 20 kt possible. /JLiu

MARINE
Post frontal conditions are creating breezier winds and elevated seas for all waters except inner southern waters.
Currently the northern waters are gusting to around 25-30 kt, with the southern waters closer to 20-25 kt. Seas in the northern waters will see a sharp but temporary increase in wave heights, peaking around 12-13 ft at 9 seconds Wednesday morning. The southern waters should not be affected. The Small Craft Advisory thus continues until Thursday afternoon as winds and seas remain elevated.

As we move into Thursday, calmer winds/seas return for a day followed by yet another weather disturbance moving into the region from the NNW late Friday/Saturday continuing the rather progressive and active weather pattern. Seas likely rise to 7-10 feet at 8-9 seconds on Saturday before decreasing Sunday into early next week - wave steepness may again be a concern Saturday.
-mh/JLiu

PQR WATCHES/WARNINGS/ADVISORIES

OR...None.
WA...None.
PZ...Small Craft Advisory until 5 PM PDT Wednesday for PZZ210-251-252- 271>273.

Vancouver
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Tue -- 01:48 AM PDT     0.44 feet Low Tide
Tue -- 04:20 AM PDT     Moonset
Tue -- 05:32 AM PDT     Sunrise
Tue -- 06:10 AM PDT     1.76 feet High Tide
Tue -- 02:29 PM PDT     -0.14 feet Low Tide
Tue -- 07:05 PM PDT     1.26 feet High Tide
Tue -- 07:14 PM PDT     Moonrise
Tue -- 08:42 PM PDT     Sunset
Tue -- 10:09 PM PDT     1.00 feet Low Tide
Tue -- 11:02 PM PDT     1.00 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION

Vancouver, Columbia River, Washington (dubious accuracy), Tide feet

Knappa
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Tue -- 12:46 AM PDT     8.18 feet High Tide
Tue -- 04:22 AM PDT     Moonset
Tue -- 05:34 AM PDT     Sunrise
Tue -- 08:14 AM PDT     -0.12 feet Low Tide
Tue -- 01:58 PM PDT     6.52 feet High Tide
Tue -- 07:19 PM PDT     Moonrise
Tue -- 07:51 PM PDT     2.23 feet Low Tide
Tue -- 08:48 PM PDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION

Knappa, Knappa Slough, Columbia River, Oregon, Tide feet

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Portland, OR,