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Area forecast discussion 
National Weather Service Pendleton or
300 am PDT Tuesday may 26 2015

Short through Wednesday upper low over
eastern Washington early this morning will slowly drift southeast
through this period. This low will be centered over extreme
northeast Oregon by Wednesday morning and southern Idaho by early
Thursday morning. Thus a seasonally mild, but unstable air mass will
persist over the interior northwest through much of this period. A
few showers will be possible through this morning over some of our
northern zones. Daytime heating will cause the potential for showers
to increase over the region, while also allowing for isolated
thunderstorms. At this time expect all of our Washington zones and
our eastern zones in Oregon to see the potential for showers and
storms this afternoon and evening. A few showers should persist
overnight into Wednesday morning across many of our northern and
eastern zones. Isolated to scattered showers and isolated
thunderstorms are expected again Wednesday afternoon and evening.
Some stabilization is expected from the basin south into central
Oregon. Thus will continue to indicate showers and storms along and
near the Cascade crest, and from the northern Blue Mountain
foothills south to Grant County and east to Wallowa County. 90

Long term...Thursday through Monday...Thursday a weak ridge builds
over the region, but have kept a chance of a shower in the higher
terrain in the eastern mountains and along the east slopes of the
central Washington Cascades for Thursday. Thursday night a weak flat
middle/upper level ridge is over the region with associated sinking air
providing dry conditions overnight through Friday morning. Friday
the ridge remains over US with the ridge axis having moved east into
Idaho, which allows flow aloft to back to the southwest, which
enables Pacific moisture to begin entering the region. This moisture
flux into the forecast area increases through the weekend for a
chance of showers in the higher terrain of central and northeast
Oregon on Saturday and Sunday as well as in the Blue Mountains of
southeast Washington. Daytime surface heating will yield marginally
instability for a slight chance of afternoon and early evening
thunderstorms over the mountains through Monday. Polan


Aviation...12z tafs. Few remaining showers moving across the
Columbia Basin late this evening with ceilings 050-080. Showers and
isolated thunderstorms will increase in coverage Tuesday afternoon
and evening for ykm dls psc PDT alw. Clear to partly cloudy skies
for rdm bdn the next 24 hours. Polan


Preliminary point temps/pops...
PDT 76 51 78 53 / 20 20 30 10
alw 76 56 78 57 / 30 30 30 20
psc 80 54 84 53 / 20 20 20 10
ykm 77 54 82 54 / 40 30 20 10
hri 80 52 83 52 / 20 20 20 10
eln 76 52 82 54 / 40 30 20 20
rdm 74 41 77 43 / 10 10 10 10
lgd 72 49 73 48 / 40 30 40 30
gcd 75 46 76 47 / 10 10 20 20
dls 78 56 83 58 / 20 20 10 10


PDT watches/warnings/advisories...

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