Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 200250
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
750 PM PDT Thu Apr 19 2018

.SHORT TERM...Tonight and Friday...High pressure ridge building over
the region will persist through Friday. Skies will be mostly clear
tonight but then some increasing high clouds Friday. Temperatures
will be a little warmer Friday and winds will continue to be light.


&&

.PREV DISCUSSION... /issued 315 PM PDT Thu Apr 19 2018/

SHORT TERM...Tonight through Sunday...Upper level low pressure
continues to dig across the southern Great Basin, with ridging
approaching the WA/OR coast. Mostly sunny skies prevail this
afternoon across most areas, with a few more clouds lingering
across central and far northeast OR. Ridging will enter the
region tonight, crossing the area Friday. Dry conditions will
prevail, with seasonably cool lows tonight, and seasonably warm high
temperatures Friday. The ridge will flatten by Friday night as a
shortwave and surface cold front approaches from the northwest. The
wave will clip the area late Friday night and Saturday. Deep layer
moisture will be quite limited and located mostly to the north of
the area. Will use chance PoPs late Friday night and Saturday for
the east slopes of the WA Cascades, with little/no precip expected
elsewhere. The main effect of the system will be breezy to windy
conditions Saturday afternoon/evening. Model guidance continue to
have a decreasing trend, so expect windy, but not advisory level
winds for the Kittitas Valley, with breezy to locally windy
conditions for the Columbia Basin and Blue Mountain foothills.
Dry zonal flow will prevail Saturday night, with another weak
short wave progged to dig across the interior Pacific northwest
Sunday. With very little moisture to work with, dry conditions can
be expected. Near normal high temperatures can be expected for the
weekend, with mild temperatures Friday night with more cloud cover
overnight.

LONG TERM...Sunday night through Thursday...Models in good
agreement in building an upper level ridge over the forecast area
through at least Monday night.  However, the models begin to differ
in their break down of the ridge Tuesday.  GFS flattens the ridge
quicker while the ECMWF shows the ridge pushing eastward over Idaho.
By Tuesday night, the GFS shows a weak disturbance moving over the
area. The ECMWF shows this same disturbance moving through the area
Wednesday morning and is farther north. Given the discrepancies,
will keep a slight chance of afternoon and evening mountain showers
over Oregon on Tuesday.  A weak shortwave ridge is expected to build
over the region Wednesday in the wake of the aforementioned
disturbance.  Finally, there may be just enough instability and low
level moisture to introduce a slight chance of afternoon and evening
showers over the mountains Thursday.  Otherwise, the weather will
remain dry through the period.  Temperatures will remain above
normal. Earle

AVIATION...00Z TAFs...VFR conditions will continue the next 24
hours. Thin cirrus will spread across the area tonight with some mid
clouds in the western CWA towards morning. Winds will be less than
12 kts with higher gusts in the afternoon and early evening hours.
Earle

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  38  68  45  62 /   0   0  10   0
ALW  39  70  46  63 /   0   0  10  10
PSC  41  72  48  66 /   0   0  10   0
YKM  40  70  43  62 /   0   0  10   0
HRI  40  72  46  65 /   0   0  10   0
ELN  37  66  40  56 /   0  10  20  10
RDM  31  69  35  61 /   0   0  10   0
LGD  34  65  43  58 /   0   0  10  10
GCD  32  66  40  61 /   0   0   0   0
DLS  42  71  46  63 /   0   0  10  10

&&

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

$$

91/91/91



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