Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 240325
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
725 PM PST Thu Feb 23 2017

.SHORT TERM...Tonight and Friday...A northwest flow with decreasing
showers over the region this evening which will end shortly leaving
mostly clear to partly cloudy skies overnight. Another shortwave
dropping out of western Canada will move off the Pacific Northwest
coast on Friday. This will turn the flow southwesterly and will see
a few snow showers develop over the mountains in the afternoon that
will end in the evening.


&&

.PREV DISCUSSION... /issued 340 PM PST Thu Feb 23 2017/

SHORT TERM...Tonight through Sunday Night...A mid/upper level
trough will continue to persist across the Pacific Northwest
through the short term period. A weak wave will exit the area to
the northeast this evening...with isolated/scattered snow showers
decreasing across the eastern mountains. Another area of low
pressure will dive south offshore the WA/OR coast Friday into
Saturday...digging across CA and the Desert Southwest Saturday.
Mainly dry conditions will prevail for the lower elevations...with
slight chance to low end chance PoPs for the mountains. Snow levels
will generally run in the 750-1500 ft range...so most of the precip
will remain snow. A brief period of dry conditions area wide can be
expected Saturday as shortwave ridging crosses the area as the low
digs well to the south. A more potent system will approach from the
NW Sunday...moving inland across OR Sunday Night. With the initial
trajectory of the system...will keep lower elevation PoPs in the
slight chance to low end chance range for Sunday...with some
increase in coverage Sunday Night as the trough moves inland.
With increasing upslope flow...will use mainly likely PoPs for the
higher elevations. With precip amounts in the one tenth inch per 6
hour range for the mountains...and snow levels remaining
low...several inches of snow will be possible across the NE OR
mtns and the immediate east slopes of the Cascades. Do not expect
significant snows for the lower elevations...but some minor accums
cannot be ruled out. With the continued troughy pattern...expect
temperatures to run 5-7 degrees below normal.

LONG TERM...Monday through Thursday. The Pacific NW will be located
between a longwave ridge offshore and a broad upper trough east of
the Rockies Monday through Tuesday...leaving the forecast area under
a N-NW flow aloft.  Unseasonably cold temperatures...low snow levels
and scattered-numerous snow showers will result.  The best chance of
snow will be over the eastern Oregon zones...as drier air from the
north will spread across eastern Washington and any snow will
primarily be orographic...especially on Tuesday.  The ridge offshore
will shift eastward across WA/OR the remainder of the extended
period with drier conditions and near seasonal temperatures
returning Wednesday-Thursday. The 12Z ECMWF is flatter with the
ridge compared to the GFS on Thursday which would mean more cloud
cover and cooler temperatures. No wind concerns are anticipated
during the long term period. Wister

AVIATION...00Z TAFs. VFR conditions and winds less than 15 knots
will prevail for the next 24 hours.  Skies will mainly be SCT at
3500-6000 feet AGL and SCT-BKN AOA 15K.  After 15Z on Friday...mid
level clouds will increase from the west with BKN-OVC 7K-10K feet by
00Z/25th. Wister

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  26  40  25  39 /   0  10  10  10
ALW  27  41  26  41 /   0  10  10  10
PSC  26  44  25  44 /   0  10  10  10
YKM  21  40  23  41 /   0  10  20   0
HRI  27  43  25  43 /   0  10  10  10
ELN  17  37  18  36 /  10  20  20   0
RDM  18  37  20  39 /  10  10  20  10
LGD  22  34  19  35 /  10  20  20  20
GCD  18  33  19  34 /  10  10  20  20
DLS  26  43  25  43 /  10  20  20  10

&&

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

$$

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