455
FXUS66 KPQR 170358 AAA
AFDPQR

Area Forecast Discussion...Updated
National Weather Service Portland OR
858 PM PDT Thu May 16 2024

Updated Aviation...

.SYNOPSIS...A weak cool front just offshore will push inland tonight.
Spotty drizzle or light rain possible, but mainly this front will
reinforce the cooler onshore flow. So, back to typical mid-spring
pattern, with morning clouds giving way to partly sunny afternoons.
Temperatures will be more typical of mid-May. Another weakening front
will arrive later Friday into Friday night, with a better chance of
showers. Unsettled weather will continue into early next week.

&&

.SHORT TERM...(Thu afternoon through Sunday)...Weather patterns have
shifted, bringing weather and temperatures more in alignment with
what would expect for mid-May. Upper trough will sit over the
southeast Gulf of Alaska into western Canada through the weekend. A
weakening front is pushing into far northwest Washington this
afternoon, and drapes down off the north Oregon coast. This front
will push inland over rest of western Washington and western Oregon
through this evening. But, not a lot of lift with precipitation, as
main effect will be increasing lower-mid level clouds. That said,
will keep for spotty light rain and occasional drizzle along the
coast into the nearby Coastal mtns. Otherwise, only spotty sprinkles
farther inland overnight as the front moves inland. With the marine
layer deepening, could see areas of drizzle inland early Fri am, but
suspect that mainly as move closer to the Cascades foothills.

With the deep marine layer around on Friday, will see quite a bit of
clouds around region. With cooler upper trough over the region, and
with the breaks in the cloud cover on Friday, will see isolated to
scattered showers around region. Best chance will be over the higher
terrain, including the Coast Range/Willapa Hills and the south
Washington Cascades. Still rainfall not all that much, with a Trace
to 0.05 for most areas, though a few spots could get up to 0.15 inch,
but those more likely in the Willapa Hills into south
Washington Cascades.

Another weakening front will arrive later Friday into Friday night.
This front will be much like the system today, with spotty rain or
drizzle into the coastal and coastal mtn areas. But, with air mass a
bit more moist, do have a better chance of showers for Sat. Again,
any rainfall is not all that much again, and even that will favor
areas along the coast, and into the higher terrain from around
Tillamook inland towards south Washington Cascades.   /Rockey

.LONG TERM...(SUN to WED)...Little to minimal change in the
forecast for Sunday and Monday as mild temperatures and a few
sprinkles remain. Monday appears to be warmer than Sunday as
the NBM shows ranges between 66-74 degrees F (the 25th-75th
percentile) in Portland, 59-62 degree F along the coast, and
64-71 degrees F in Hood River. Any rain that does fall on these
two days will be light and showery. Long term ensembles have
narrowed in on a pattern finally where as yesterday there was
still quite a bit of variation between them. On Tuesday, there
is a trend towards troughing but the depth of that trough still
remains unknown. Given that that is 6 days out, there is still
time for it to shift. Have trended in the route of the grand
ensemble which is showing moderate troughing, rain, northerly
winds and moderate temperatures. The long-term forecast is
unremarkable but there remains high uncertainty on Tuesday and
Wednesday in regards to temperatures and precipitation
accumulation. /Muessle

&&

.AVIATION...Onshore flow along with a weak frontal passage will
bring increasing cloud cover and light precipitation through
around 15Z Friday. Widespread MVFR, with occasional IFR
conditions along the coast, with increasing cloud cover for inland
locations. Overall, likely to remain VFR inland, but could see
pockets of MVFR after 10Z, with patchy drizzle/light rain in
spots. Slow improvement expected across the airspace after 15Z
Friday with predominately VFR flight conditions. Gusty
north/northwesterly winds up to 20 kt for inland locations
through 11Z Friday. Higher westerly gusts likely near KTTD with
gusts up to 30 kt through the same time frame.

PDX AND APPROACHES...VFR, with increasing clouds. Generally, CIGS
will remain VFR 3500 to 4500 ft through the TAF period. Breezy
northwest winds with gusts up to 20 kt through 11Z Friday. /42
&&

.MARINE...A weak front moved across the waters this afternoon.
Behind the front will see northwest winds increase to around 20-25
kt over most of the waters. It does appear the nearshore zones
PZZ252 & 253 will attain Small Craft Advisory winds tonight or
Friday. However with relatively short period fresh swell moving
into the waters later tonight and Friday seas will be rather
choppy at 7 to 9 ft with a 9 second period.

Friday and into the weekend will see a return of high pressure
which will result in a typical summertime northerly flow regime
with wind gusts peaking in strength during the afternoon/evening
hours each day. The strongest winds will occur over the southern
waters where small craft advisory level wind gusts to 25 kt are
likely to occur again.
/mh

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...Small Craft Advisory until 8 PM PDT Friday for PZZ251-271-272.
     Small Craft Advisory from 6 AM to 8 PM PDT Friday for PZZ252.
     Small Craft Advisory until 6 AM PDT Friday for PZZ273.

&&

$$

www.weather.gov/portland

Interact with us via social media:
www.facebook.com/NWSPortland
www.twitter.com/NWSPortland