458
FXUS66 KPDT 151733 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
930 AM PST Fri Nov 15 2019

Updated Aviation Discussion

.SHORT TERM...A cold front is tracking across WA/OR, and satellite
clearly shows the back edge right along the Cascade Range. Less
than 0.10 inch of rain has fallen so far in our western forecast
area. The fast moving front will sweep across the Columbia Basin
and central OR over the next 4-5 hours then the remainder of the
forecast area this afternoon. The good news is that the front will
help break the low level stratus that has covered the lower
elevations for several days. It will still be mostly cloudy with
broken- overcast mid and high level clouds. Southwest-west winds
will increase with local gusts around 25-30 mph. The east slopes
of the WA/OR Cascades and the Blue Mountains will receive about
0.1-0.3 inch of rain (snow levels 6000-7000 feet) and up to 0.10
inch elsewhere. Scattered mountain showers will continue this
evening then end overnight. Snow levels will lower to around 5000
feet tonight with less than an inch of snow accumulation.

The weather will be mild and benign over the weekend as a flat
ridge remains over the area. Pacific moisture will override the
ridge and across the northern half of WA, and our forecast area
will be partly to mostly cloudy. There may be some patchy fog but
the westerly flow and cloud cover should limit a widespread fog
development. Wister

&&

.PREV DISCUSSION... /issued 335 AM PST Fri Nov 15 2019/

LONG TERM...Sunday night through Thursday...Ridging will build
back Sunday into Monday over the region with less cloud cover and
clearing conditions for much of Oregon and the Washington Basin.
However, cloud cover and some isolated showers remain possible for
the Washington Cascade crest. Meanwhile, a mid-level shortwave
will pivot around the parent Aleutian low working it`s way toward
the Pac NW coast on Monday. Mid range models are aligning more,
indicating a sfc low pressure system will move through the area
late Monday night into Tuesday. Rain along the Cascade crest will
be likely. Showers and brief periods of rain will be likely for
the Blue Mountains of OR and WA and, at this time, passing showers
seem possible for the Columbia Basin. Breezy conditions will
accompany the systems passage. Snow levels will remain relatively
high around 7-8kft but will drop steadily as the system slides to
our east. At this time, only the Cascade peaks, Wallowas, and
highest areas of the Blue Mtns are likely to see snow.
Temperatures will cool off early to mid-week as a generally colder
airmass settles in. Model solutions begin to diverge as this Mon-
Tue system moves across our region though consensus is for a
cutoff low to form to our south as tailing vorticity from the
trough drops toward southern California and interacts with
southern stream momentum. Such a pattern would favor ridging and
generally cool and tranquil weather for mid week next week.

AVIATION...18Z TAFS...Band of rain with lower stratus will affect
PSC/PDT/ALW with IFR cigs and vsby through 23z with low clouds
causing IFR cigs at DLS through 24z.  Partial clearing will spread
west to east through the afternoon and continue through the evening
with VFR expected at all sites through the rest of the period. Winds
will become west 5 to 10 kts across the area and is expected to keep
airmass mixed and only some patchy fog overnight and early morning
Saturday. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  51  36  54  37 /  60  20  10  10
ALW  50  39  54  39 /  70  20  10  10
PSC  51  35  53  37 /  60   0  10  10
YKM  50  32  52  35 /  80   0  10  10
HRI  51  36  53  35 /  60  10  10  10
ELN  50  34  50  35 /  80  10  20  10
RDM  54  29  57  30 /  30  10   0   0
LGD  51  34  52  34 /  70  30  10  10
GCD  52  34  54  33 /  40  20   0   0
DLS  53  39  55  36 /  80  10  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Air Stagnation Advisory until noon PST today for WAZ027.

&&

$$

85/93

NWS PDT Office Area Forecast Discussion