730 
FXUS66 KPDT 200330
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
830 PM PDT FRI AUG 19 2016

.SHORT TERM...Tonight through Saturday afternoon...The Red Flag
Warnings for winds and low relative humidity will be allowed to
expire at 9 PM PDT this evening.

Forecast area is under the influence of the eastern flank of a
mid/upper level high pressure ridge near 130w, which will continue
to deliver dry conditions through Saturday afternoon.  Forecast is
on track and no updates are expected.  Polan

&&

.PREVIOUS DISCUSSION... /issued 227 PM PDT FRI AUG 19 2016/ 

SHORT TERM...Today through Monday...The dry generally quiet weather
pattern will continue tonight and tomorrow as our area remains in a
northerly flow. Northerly winds will continue to be breezy at times
through this evening before diminishing quickly overnight. Low
temperatures will be rather cool tonight under clear skies...expect
lows in the 50s...except upper 30s and 40 mountains...this is a few
degrees below average. Temperatures will remain very warm on
Saturday under mostly clear skies. There could be some sct cirrus
clouds over our northern Washington zones in the afternoon. Highs
will reach 95 to 102 in the lower basin and surrounding valleys.
winds will remain light through the day on Saturday...less than 10
mph areawide. On Sunday a rather strong marine push moves into the
central and western portion of our CWA out ahead of an approaching
upper level trough. Pressure and temperature gradients will increase
along the Cascades and eventually push into the Columbia Gorge and
Basin by afternoon. This will cause westerly winds to
increase...reaching 15 to 25 MPH with gusts up to 35 MPH Sunday
evening in these areas. This will combine with very low humidity to
cause additional fire weather concerns. Please see the fire weather
discussion below for more details. The winds may also be strong
enough late Sunday to produce some patchy blowing dust over the
Lower Columbia Basin and parts of the Blue Mountain Foothills.
Temperatures will remain hot on Sunday...except falling several
degrees in the Eastern Columbia Gorge, near The Dalles. On Monday
the dry upper level trough moves overhead...with just some
additional cloud cover and breezy conditions expected. Humidity
levels will begin to increase...especially in the Columbia
Gorge...but will still remain dry. 77

LONG TERM...Monday night through Friday...A quiet weather pattern
will continue through the extended period. There will be a lack of
storm systems next week with the pattern expected to shift from weak
ridging to a weak trough. There could be a little instability and
moisture over the eastern mountains by Friday...but potential for
thunderstorms appears too meager to include in the forecast at the
present time. There could be a bit of a north to northeast breeze on
Thursday. Relative humidities will be quite low so there could be
some fire weather concerns. Temperatures will remain near to above
normal for this time of year but not excessively hot. Nights are
also getting longer so it will be a bit cooler at night especially
in the mountain valleys. 78 

AVIATION...00Z TAFs...VFR conditions with just some very high cirrus
is expected through the forecast period. North-northeast winds
through early this evening will become terrain driven tonight.
Winds will be less than 10 kt on Saturday. 78

FIRE WEATHER...Red Flag Warnings are in effect until 9 PM for
gusty winds and low humidity for the Washington portion of the Lower
Columbia Basin and Simcoe Highlands (WA fire zones 639 and 641) as
well as the East Slopes of the Northern Oregon Cascades and Central
Oregon (OR fire zones 610...611 and 640). The gusty winds are not
widespread but enough sustained winds and gusts to keep the warning
in effect.  Winds should diminish overnight.  Although the winds
will not be a concern on Saturday through early Sunday...the dry and
marginally unstable air mass bringing the Haines to a 5 (moderate
category) and the low humidity will be a concern.  The Haines is not
expected to reach a high category of 6.  An upper-level shortwave on
Sunday evening will cause marine air to spill through the Eastern
Columbia River Gorge and possibly as far east-southeast as Boardman
and Ione.  This is the area of most concern for gusty winds and low
humidity Sunday afternoon...and a Fire Weather Watch has been issued
for Sunday afternoon through Monday evening for this area.  The
winds will not be as strong on Monday but enough to extend the watch.
Wister

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  95  59  96 /   0   0   0   0 
ALW  60  95  65  96 /   0   0   0   0 
PSC  52  97  60 100 /   0   0   0   0 
YKM  51  99  60  96 /   0   0   0   0 
HRI  51  97  58  98 /   0   0   0   0 
ELN  51  98  58  92 /   0   0   0   0 
RDM  45  96  48  94 /   0   0   0   0 
LGD  45  92  48  94 /   0   0   0   0 
GCD  49  95  51  95 /   0   0   0   0 
DLS  57 101  63  92 /   0   0   0   0 

&&

.PDT Watches/Warnings/Advisories...
OR...Fire Weather Watch from Sunday afternoon through Monday evening 
     for ORZ639-641.

     Red Flag Warning until 9 PM PDT this evening for ORZ610-611-640.

WA...Fire Weather Watch from Sunday afternoon through Monday evening 
     for WAZ639-641.

     Red Flag Warning until 9 PM PDT this evening for WAZ639-641-675.

&&

$$

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