FXUS66 KPDT 272151

Area Forecast Discussion
National Weather Service Pendleton OR
250 PM PDT Thu Apr 27 2017

.SHORT TERM...Tonight through Sunday afternoon...Scattered rain and
snow showers over the southern Blue Mountains will continue through
this afternoon and then taper off and end by late this evening.
Water vapor satellite imagery loop shows a mid/upper level ridge of
high pressure with ridge axis near 140W this afternoon. The ridge
will move slowly eastward over the next couple of days, thus
providing dry conditions to the interior Pacific Northwest. Then a
weak mid/upper level shortwave moves over and through the ridge on
Saturday night and Sunday spreading showers over the mountains with
snow level 6000-7000 feet Saturday night and Sunday. Wind Advisory
remains in effect for the Kittitas Valley until 9 PM PDT. Polan

.LONG TERM...Sunday night through Tuesday night...A dry nwly flow
will be over the region on Sunday night. On Monday a low amplitude
ridge will build over the area with dry and warm conditions. Highs
will be well into the 60s lower elevations with 50s mountains. On
Monday night and into the first part of Tuesday a weak disturbance
embedded in the nwly flow aloft will graze the area...passing mostly
to the north. This may produce a few light mountain rain showers. It
will be warm on Tuesday with highs in the 70s lower elevations with
mid 50s to lower 60s mountains. 78

Wednesday morning through Friday morning...Models are in reasonable
agreement that a ridge will be centered along the coast with little
in the way of sensible weather expected through the day on Thursday.
Temperatures on Wednesday will be warm with highs in the upper 70s
in the lower elevations and 60s in the mountains. Thursday will be
even warmer with a good portion of the area approaching 80 for a
high. Model agreement begins to fade on Thursday with the ECMWF
breaking down the ridge quickly as a trough approaches from the
west. The GFS is slower and weaker with this feature. Have opted to
defer to the GFS for now as it been most consistent over the last
couple runs while substantial differences have appeared between
ECMWF runs. As the ridge begins to break down Thursday night into
Friday showers and possibly a few rumbles of thunder will return to
the area. Peck


.AVIATION...00Z TAFS...VFR conditions will prevail through the
forecast period. Fairly extensive SC field developed today with
daytime heating. Expect much of this activity to dissipate after
sunset. However there will be a few lingering clouds at 5-7 kft and
some mid cloud above tonight. There will be fewer clouds on Friday.
Winds will be 15-25 kt early this evening but decrease overnight to
5-15 kt and continue on Friday. 78


PDT 37 58 37 63 / 10 10 0 0
ALW 42 61 42 65 / 10 10 0 0
PSC 40 65 38 68 / 10 0 0 0
YKM 37 64 37 66 / 10 10 0 0
HRI 40 63 37 66 / 10 0 0 0
ELN 38 60 36 62 / 10 10 0 0
RDM 25 55 25 63 / 20 10 0 0
LGD 35 54 34 61 / 20 10 10 0
GCD 30 53 27 62 / 50 10 0 0
DLS 42 62 41 65 / 10 10 0 0


WA...Wind Advisory until 9 PM PDT this evening for WAZ026.



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