Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 251723 AAA
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
925 AM PST Sat Feb 25 2017

Updated Aviation Discussion

.SHORT TERM...upper ridge over the area today with fairly dry
northwesterly flow. Expect partly cloudy skies with temperatures
in the 30s to mid 40s and light winds. Models consistent in
showing the next system moving southward into the Pacific
northwest later tonight with increasing clouds and light snow
developing late. The low will move slowly across Washington and
Oregon Sunday into Sunday night with snow likely. The Columbia
basin may mix over to rain for a while Sun afternoon with temps
warming into the upper 30s. Cold northwest flow aloft will likely
keep snow going into Monday over the Cascades and Blues. 94

&&

.AVIATION...18z TAFs. KBDN continues to observe OVC021 this
morning...although web cams show the stratus thinning out.  VFR
conditions will prevail at all TAF sites through 12Z/26th.  Mid
level clouds will increase tonight through early Sunday morning then
lower to near or slightly above MVFR between 12Z-18Z.  Light snow
showers  will develop in eastern Washington and northeast Oregon
during this time...resulting in MVFR VSBY/CIGS.  Winds will be less
than 10 knots for the next 24 hours.  Wister

&&

.PREV DISCUSSION... /issued 305 AM PST Sat Feb 25 2017/

SHORT TERM...Today through Monday afternoon...A mid/upper level
trough will move south and out of extreme southwest Oregon into
California today resulting in a mid/upper level ridge of high
pressure building over the forecast area for mainly dry conditions
today, except for a slight chance of snow showers in the Blue
Mountains this afternoon due to orographic lift. Another mid/upper
level upper trough then moves south out of British Columbia tonight
and spreads a chance of snow to the east slopes of the central
Washington Cascades late this evening with snow spreading south and
east to the Blue Mountains as well as along the Foothills of the
Blues overnight. After daybreak on Sunday snow will spread into
central Oregon and the Ochoco-John Day Highlands and also the
Wallowa and Elkhorn Mountains. The upper trough will move over the
region Sunday night through Monday afternoon. Below normal
temperatures and very low snow levels will yield predominantly snow.
Snow accumulations in the Blue Mountains will be on the order of 3
to 8 inches with this system from Sunday through Monday afternoon.
Polan

LONG TERM...Monday night through Saturday...EC and GFS in good
agreement showing northwest flow will gradually become more westerly
by Thursday. Weak disturbances moving through the northwest flow
will bring light rain and snow showers to mainly the mountain areas.
Snow levels 1-2k rising to between 2500-3500 feet by Thursday.  A
stronger short wave trof will likely bring stronger winds Friday
night into Saturday across mainly Washington. Although some warming
will occur by midweek, temperatures will likely average 3 to 5
degrees below normal.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  44  28  38  26 /  10  30  70  20
ALW  44  29  38  27 /  10  30  80  30
PSC  46  29  41  26 /   0  20  70  30
YKM  42  25  38  23 /   0  30  70  20
HRI  45  28  41  27 /  10  20  70  20
ELN  39  23  34  18 /   0  60  70  20
RDM  41  23  38  22 /   0  10  60  40
LGD  38  25  35  24 /  10  20  70  60
GCD  38  23  36  23 /  10  20  60  60
DLS  45  30  40  27 /   0  20  80  20

&&

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

$$

94



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