National Weather Service Raw Text Product

625 
FXUS66 KPDT 091059
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
259 AM PST Mon Nov 9 2020

.SHORT TERM...Today through Wednesday...Snowfall across the
forecast area has mostly ended this early morning with a large
portion of the forecast area having cleared out. There is still
some cloud cover from southern Deschutes county northeast into
Wallowa county where a few embedded pockets of light snow could be
falling in the higher elevations. Expect the rest of this cloud
cover to continue to decrease this mornings as northerly flow
aloft filters in a dry and cold air mass into the region.
Temperatures this morning will likely be the coldest of this work
week, with temperatures in the Columbia Basin in the upper teens
to lower 20s and in the teens everywhere else.

Today, quick moving upper level ridge will move over the forecast
area, allowing temperatures to rebound and warm into lower to mid
40s across the lower elevations and mid to upper 30s for the 
mountains. Clear skies this afternoon will begin to give way to 
increasing cloud cover ahead of the next weather system 
approaching the forecast area from the northwest. This evening 
into early tomorrow, upper level shortwave and cold front will 
swing around an approaching upper low and move across the forecast
area from the northwest, producing mainly mountain snow and lower
elevation rain. Precipitation may start off as mixed across 
foothill locations overnight, transitioning to rain before sunrise
Tuesday morning. Breezy westerly winds will develop behind the 
frontal boundary across the forecast area early Tuesday, lingering
into Tuesday night. Another shortwave swinging around the upper 
low and across the forecast area starting Tuesday afternoon will 
reinforce precipitation chances across the forecast area, with 
lower elevation rain and mountain snow continuing into Wednesday 
morning. With the longevity and intensity of these combined 
systems Tuesday, will keep a close eye on snow amounts in the Blue
Mountains and Wallowa County as winter weather advisories may 
needed. Precipitation chances will taper off by late Wednesday 
morning with clearing skies through the afternoon and evening as 
an upper level ridge moves across the PNW. Lawhorn/82


.LONG TERM...Thursday through the Weekend... 
Models continue to depict a rather active series of storm systems 
from late week on through the weekend. This will bring episodes of 
low elevation rain and mountains snow, which may be moderate to 
heavy at times.

Within a fast northwest flow pattern, several storm systems are 
expected to move from northwest to southeast across the region. The 
first, and less impressive system looks to arrive late Thursday into 
Friday. A second more potent systems then looks to impact the region 
Friday night into Saturday. Thereafter, models diverge slightly in 
terms of additional shortwave energy, but the pattern will generally 
remain favorable with a strong jet stream overhead and the potential 
for additional fast moving impulses through the remainder of 
the weekend.

With back to back episodes of precipitation, lower elevations look 
to pick up on some additional beneficial rains ranging from a tenth 
of an inch of liquid in the heart of the Columbia Basin to perhaps a 
half inch of liquid in ares where upslope flow leads to more 
efficient rain processes.

The most impactful aspect of this rapid fire set of storms will be 
mountain snow accumulations, with little time for melting or 
compacting between waves of snow. Snow levels generally look to 
fluctuate between 2500 and 4000 ft with the lower snow levels across 
central Washington. The heaviest snow totals will likely reside 
above 3000 feet, which will certainly affect the Cascade passes and 
more traveled routes over the mountainous terrain of central and 
northeast Oregon into southeast Washington. A great deal of 
uncertainty remains in terms of exactly how much snow can be 
expected during this timeframe, and how much melting or compacting 
might occur, but confidence is high that there will be some travel 
impacts from late week into the weekend, so it would be wise to 
check the forecast frequently. 79/Austin


&&

.AVIATION...12z TAFs...
VFR conditions expected for much of the period as we remain between 
storm systems. Winds to generally remain 10 knots or less. By 03z to 
06z, clouds and precipitation will increase from west to east. KDLS, 
KPDT, and KALW look to have the better chance at seeing -RA with 
lesser chances elsewhere. At this time, confidence remains low on 
any impacts to visibilities or ceilings.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  40  33  45  34 /   0  50  50  50 
ALW  42  33  46  34 /   0  50  50  70 
PSC  45  35  50  35 /   0  30  20  30 
YKM  43  26  49  26 /  10  20  20  20 
HRI  45  34  51  35 /   0  30  30  30 
ELN  42  26  45  26 /  10  30  30  30 
RDM  42  26  45  27 /   0  10  40  40 
LGD  36  27  38  30 /   0  60  70  70 
GCD  37  28  41  29 /   0  50  60  70 
DLS  46  33  49  37 /  10  30  50  40 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

SHORT TERM...82
LONG TERM....79
AVIATION...79