Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 242126
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
226 PM PDT SUN JUL 24 2016

.SHORT TERM...Tonight through Wednesday evening...The Pacific
Northwest will continue under a mostly dry westerly flow through
this period. Will see clear conditions with terrain driven winds
tonight. A weak wave within this flow will move gradually across the
region late Monday and Tuesday. The threat of thunderstorms and
showers with this system will be limited due to a general lack of
moisture. The best available moisture will be over portions of the
Washington Cascade east slopes Monday afternoon and evening as the
wave moves into western Washington. Increasing westerly surface flow
across Cascade east slopes will work against convective development,
but there may be enough wind convergence along some of the ridges to
cause local convection. Thus will indicate a slight chance of
thunderstorms and showers over the ridges of the Washington Cascade
east slopes from near Cliffdell north through western Kittitas
county. Otherwise will continue the dry forecast elsewhere. Winds
will become breezy near the Gorge and in the Kittitas valley by
Monday evening. Breezy winds will extend from these areas into
portions of the Columbia Basin on Tuesday. The air mass across the
region will become increasingly dry Tuesday through Wednesday. Thus
expect fair and dry conditions Tuesday through Wednesday evening.
High temps will run a 2-6 degrees above seasonal through this period
with highs on Monday being the warmest. 90

.LONG TERM...Thursday through Sunday...The main forecast concern is
the warming trend that results in hot conditions and well above
normal daytime high temperatures that are expected for the latter
part of the work week. Highs Thursday will be in the 90s. Friday
will be the warmest day with highs in the mid 90s to lower 100s.
Highs in the mountains will be in the upper 70s to the upper 80s on
Thursday and Friday. Mid/upper level high pressure will be over the
desert southwest and the Great Basin and will put the forecast area
on the northern flank of the high pressure dome. Sinking motion in
the atmosphere associated with the High pressure will produce the
heat wave and dry conditions through Friday night.

Models are in good agreement on Saturday and Sunday and indicate
that a cooling trend will begin on Saturday and continue through
Monday due to a mid/upper level trough in the NE Pacific moving
through the interior Pacific Northwest on Saturday/Sunday. The upper
trough will bring a dry marine push and cooler air into the region
resulting in high temperatures on Sunday in the mid 80s to lower
90s, except in the upper 60s to lower 80s in the mountains. The
marine push will also bring breezy conditions to the Eastern
Columbia River Gorge, the Lower Columbia Basin, and the Foothills of
the Blue Mountains, and windy conditions to the Kittitas Valley.

The GFS model continues to show some mid level moisture being
transported northward Saturday into central and NE Oregon, but the
other models keep the forecast area dry through the weekend. Polan

&&

.AVIATION...00Z TAFs...VFR conditions and clear skies will occur for
the next 24 hours. Sustained winds will be 10 kts or less. Polan

&&

.FIRE WEATHER...The weak disturbance on Monday will increase the
onshore flow west of the Cascades and allow cool marine air to seep
through the Eastern Columbia River Gorge where the winds will
increase to around 15-25 mph in the afternoon and evening. The
relative humidity will be around 20-25 percent. These conditions are
just below red flag warning criteria but will be addressed in the
fire weather forecast. The marine layer west of the Cascades will
deepen slightly on Tuesday...and the marine surge will be a little
stronger with winds increasing along the WA/OR border from The
Dalles to Pendleton and south to Condon. Winds in this area will
mainly be 10-20 mph with higher gusts and the relative humidity
around 20-25 percent. Once again...it is a concern but not enough to
warrant any fire weather watches for Tuesday.  As stated in the
short and long-term discussions...it will be hot and dry this week.
The air mass will become more unstable by Saturday. Hot...dry and
unstable air at the end of the week could mean extreme fire weather
conditions. Wister

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  56  95  63  93 /   0   0   0   0
ALW  63  96  69  93 /   0   0   0   0
PSC  56  98  65  97 /   0   0   0   0
YKM  58  98  65  95 /   0   0   0   0
HRI  55  97  66  96 /   0   0   0   0
ELN  59  94  67  91 /   0   0   0   0
RDM  50  93  51  89 /   0   0   0   0
LGD  49  92  58  90 /   0   0   0   0
GCD  54  95  57  93 /   0   0   0   0
DLS  64  94  67  89 /   0   0   0   0

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

$$

90/99/99/85



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