Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 250545 AAA
AFDPDT

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
945 PM PST Fri Nov 24 2017

Updated Aviation Discussion

.SHORT TERM...Mainly clear skies over the forecast area this
evening. Satellite shows a low pressure system well off the
California coast with a large cloud shield moving northward.
Expect mid and high level clouds will gradually overspread the
region tonight into Sat morning. Models continue to show a warm
front moving through during the day. This will bring a period of
rain mostly in the afternoon and evening. Offshore cold front then
moves across the area on Sunday with additional rain and possible
late day snow for the Cascades. This system will result in some
breezy to windy conditions. 94

.AVIATION...06Z TAFs...A band of mid and upper level cloudiness is
slowly shifting into the region from the south ahead of a warm front
with SCT-BKN skies at BDN/RDM and SKC elsewhere. Under clear and
calm conditions may see some patchy morning fog developing near
YKM/PSC but do not anticipate visibilities dropping below MVFR. As
the warm front continues to push north through Saturday afternoon
light rain and VIRGA will overspread the terminals by 20-23Z.
Conditions are expected to be mainly VFR with this activity, but may
dip to MVFR at DLS and YKM in any heavier showers. Winds are
expected to be light through the period before increasing early
Sunday morning. 74

&&

.PREV DISCUSSION... /issued 400 PM PST Fri Nov 24 2017/

SHORT TERM...Tonight through Monday night...No major weather
impacts seen in the short term. Upper level ridge to continue
giving mostly clear conditions tonight with increasing clouds
after midnight. As axis of ridge moves to the east on Saturday,
the resulting southwest flow aloft returns Pacific moisture to
central Oregon by late morning and overspreading the rest of the
area during the afternoon. There is a break in the moisture surge
Saturday night and then another round arrives for Sunday. A
Pacific cold front pushes through on Monday morning and brings a
cooler and drier airmass. Snow levels above 6k should be high
enough to prevent most problems on the busy travel Sunday. And by
the time the snow levels lower on Monday, most of the moisture
will be gone. Rainfall amounts in the Washington Cascades of 1/2
to 1 inch should be less than earlier this week, so don`t expect
flood concerns at this time.

LONG TERM...Tuesday through Friday...Progressive mid/upper level
pressure pattern through Friday. Next upstream, mid/upper level
trough approaches the coast Monday night pushing a cold front
onshore and precipitation to the Cascades overnight. The trough
makes landfall Tuesday afternoon and pushes the cold front into the
forecast area during the day on Tuesday. Snow levels on Tuesday will
be 3000-4000 feet in central and SE Washington and mainly 3500-4000
feet in eastern Oregon, except 4000-5000 feet in Deschutes and Crook
Counties through Tuesday afternoon. Tuesday night the upper trough
sweeps across the region for unsettled conditions and dynamic
lift producing Basin and valley rain showers and snow showers in
the mountains. Wednesday a mid/upper level ridge of high pressure
builds over us for dry conditions. The forecast area will continue
under the ridge Thursday and Friday for dry conditions. Polan

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  32  51  41  62 /   0  30  40  60
ALW  34  52  43  62 /   0  30  40  60
PSC  31  47  38  56 /   0  30  40  60
YKM  29  45  36  53 /   0  30  50  50
HRI  30  47  38  59 /   0  30  40  60
ELN  28  43  33  50 /   0  30  60  50
RDM  26  52  41  59 /   0  30  20  50
LGD  29  48  43  57 /   0  30  20  60
GCD  29  51  45  59 /   0  30  20  50
DLS  32  47  39  55 /   0  50  40  70

&&

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

$$

94/74



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