Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 051112 AAA
AFDPQR

Area Forecast Discussion
National Weather Service Portland OR
309 AM PST Tue Mar 5 2024

.SYNOPSIS...Showers continue across NW Oregon and SW Washington
through tonight, slowly tapering off everywhere except for Lane
County. A rough of widespread precipitation will affect Lane
County tonight through early Tuesday, bringing additional snow
above 1000-1500 ft. Mostly dry weather returns Tuesday through
Friday with the potential for fog and frost in the evening
through early morning hours. Wet and warmer weather is expected
to return later Friday into the weekend with widespread rain and
mountain snow.

&&

.SHORT TERM...THROUGH WEDNESDAY NIGHT...As of 3am Tuesday, showers
have exited most of the region, with any remaining precipitation
looking quite weak, with no chance of accumulations. The only
exception is the southern Cascades and associated foothills in the
southern part of the CWA in Lane County, which will continue to see
the northern edge of a band of showers clipping them. Snow remains
possible above 1500 feet there, but this is expected to come to an
end within an hour or two, with no more substantial snow
accumulations. Afterwards, an upper level longwave ridge pushes in
that keep conditions fairly dry from Tuesday midday through near the
end of the workweek.

With clearing skies, temperatures are expected to dip below freezing
throughout the Willamette Valley on Tuesday night/Wednesday morning.
Ensemble guidance shows nearly 100% chance of all locations in the
CWA except for the immediate coast to drop below freezing on
Wednesday morning, with 50-70% chance of the lowland valleys below 28
degrees. The chance of below-freezing temperatures drops to 40-60% on
Thursday and Friday mornings. Frost will continue to be a possible
concern during this pattern due to cool clear conditions. /JLiu

.LONG TERM...THURSDAY THROUGH MONDAY...WPC cluster analysis shows
nearly universal agreement regarding the upper longwave ridge pushing
in near the end of the workweek, with temperatures rising on Friday.
During these few days, dry conditions dominate throughout the area.
The next system begins to push in on Friday as well, with mostly just
rain expected throughout the region. It remains showery and active
into the beginning of next week afterwards. /JLiu


&&

.AVIATION...Broad upper level trough over the region shifting east
today, while west to northwest flow aloft becomes drier. Surface
observations as of 10Z Tuesday show widespread MVFR stratus with
cigs generally around 1000-2000 ft. There is a 20-40% chance that
cigs fall to IFR through 18Z this morning. Stratus expected to
gradually lift and break through this afternoon, while VFR becomes
more likely after 19-21Z Tuesday. Surface high pressure builds
across the area today with increasing northerly winds this
afternoon.

*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...Decreasing showers with predominately MVFR
cigs through this morning. Stratus expected to help surface
temperatures remain above freezing. After 20Z this afternoon,
improvement to VFR likely with dry conditions. Southeast winds
around 5 kt this morning become northwesterly by Tuesday
afternoon. /DH

&&

.MARINE...High pressure builds across the waters today through
Wednesday while an area of low pressure persists along the
northern CA coast. This will maintain northerly winds around 10-15
kt across the coastal waters. A weak front approaching the area
late Wednesday into Thursday pushes the higher pressure south
while winds shift southerly. Seas are expected to hover around 4
to 6 ft through Thursday.

A stronger front will approach the area later this week
increasing southerly winds Friday into Saturday, with around a
30-40% chance of gale force wind gusts. Long range guidance
suggest an even stronger frontal system is likely later in the
weekend. Seas will begin to build again this weekend in response
to the aforementioned frontal systems. /DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...Winter Weather Advisory until 4 AM PST early this morning for
     Cascade Foothills in Lane County-Cascades in Lane County.

WA...None.
PZ...None.

&&


&&


&&

$$

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