Wildfire in Washington, August 11 to 31, 2017

Area Forecast Discussion...Updated
National Weather Service Pendleton OR
500 PM PDT Fri Aug 11 2017

Updated AVIATION Discussion

.SHORT TERM...Tonight through Monday night...We are in the final
stages of the upper level ridge that has been parked over the region
for the past couple of weeks. The ridge will move off to the east
allowing an upper level trough off the coast to move inland over the
weekend. This will usher in cooler air beginning tomorrow with highs
staying below 100 degrees thus today will be the final day of the
heat advisory. Significantly cooler air will arrive Sunday and
Monday as the trough settles over the region with highs only in the
70s and 80s.

A small weak shortwave with its remnant of moisture will pass over
the forecast area today and overnight. This will provide some
isolated to scattered thunderstorm activity across portions of the
forecast area at times. The approaching upper level trough will push
the convective potential over to the eastern mountains Saturday
afternoon then exit the area overnight. The approaching trough will
also push a cold front into the area late Saturday night and Sunday
which will usher in the much cooler air and breezy westerly winds.
Even though it is still summer in which most cold fronts are dry the
weather models continue to indicate the front will have a band of
precipitation associated with it as it passes over the forecast
area. Thus the pops for Sunday have been updated to reflect this.
Cool yet dry conditions will prevail on Monday.

Air Quality will begin to improve Saturday and Sunday as the weather
pattern changes bringing back westerly winds which will push the
smoke and haze out of the region. However, smoke from local
wildfires will still be an issue going forward. An Air Quality Alert
for smoke (product PDXAQAPDT) remains in effect for central and SE
Washington until noon PDT Saturday. An Air Quality Alert for smoke
remains in effect until 11 AM PDT Saturday for the east slopes of
the Oregon Cascades, lower terrain elevations in central and north
central Oregon, the Columbia Basin in Oregon, the southern and
northern Foothills of the Blue Mountains in Oregon, the Ochoco-John
Day Highlands, the John Day Basin, and the Blue Mountains in eastern
Oregon. An Air Quality Alert for smoke remains in effect until noon
PDT Sunday for the Grande Ronde Valley and Wallowa County.

.LONG TERM...Tuesday through Friday night...A flat high pressure
ridge over the NE Pacific on Tuesday will gradually increase in
amplitude as it approaches the coast through Wednesday night.  This
mid/upper level pressure pattern will provide westerly to
northwesterly flow aloft over the interior Pacific Northwest
resulting in sinking motion east of the Cascades, which keeps dry
conditions through Wednesday night. The ridge then moves inland
around daybreak on Thursday and across the forecast area Thursday
afternoon/evening. The ridge will push eastward with the ridge axis
moving into Idaho overnight thus yielding winds aloft backing from
west to southwest during the day on Friday. Relative humidity in the
mid levels will be too low to support moist convection leading to
showers on Friday for a continuation of dry conditions areawide
through Friday night. Polan

&&

.AVIATION...00Z TAFs...VFR conditions will prevail through the
period, except for MVFR/IFR visibilities due to thunderstorms this
afternoon through this evening in central Oregon and the mountains
in NE Oregon. Occasional MVFR visibilities due to smoke and haze
from area wildfires will continue at KPDT, KALW and KPSC through 18Z
on Saturday. VFR conditions are expected Saturday afternoon as a
cold front brings increasing surface winds to the forecast area,
which will start to scour out the smoke and haze in the Yakima
Valley, in central and north central Oregon and the Lower Columbia
Basin through Saturday afternoon.

Moisture and an unstable airmass will trigger isolated to widely
scattered thunderstorms in the vcnty of KBDN through this afternoon
and into this evening.

Isolated to widely scattered thunderstorms will spread northeast
across the Blue Mountains through the remainder of this afternoon
and into this evening.

Gusty, variable surface winds to 45kt associated with thunderstorms
are expected at KRDM until around 02Z/12th as well as in the
vicinity of thunderstorms generally through this evening.

Winds will be less than 10kt through tonight at most TAF sites,
except at KDLS where northwest winds will be 15-20 kt with gusts to
25kt possible this afternoon through this evening. In addition,
gusty and variable winds to 45kt are expected at KRDM until around
02Z/12th and generally in the vicinity of thunderstorms through this
evening.  Polan

&&

.FIRE WEATHER...A disturbance will ride to the north and northeast
this evening, with scattered thunderstorms as far north as the
Oregon Columbia Basin/Gorge. Thus, will continue the Red Flag
Warnings for most of northern OR through this evening. Another round
of scattered thunderstorms is expected Saturday mainly over the
higher elevations as the greatest forcing shifts to the east. Red
Flag Warnings continue for Saturday aftn/evening from the Central OR
highlands northeastward to the WA Blue Mountains. Breezy conditions
will be likely tonight and Saturday, and once again Sunday afternoon
and night, but with humidities increasing, no wind/RH highlights
will be issued.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  67  95  63  83 /  10  20  20  20
ALW  71  96  65  83 /  10  20  20  20
PSC  62  98  66  85 /  10  20  10  20
YKM  66  97  61  83 /  10  20  10  20
HRI  65  97  64  84 /  10  20  10  20
ELN  65  94  63  80 /  20  20  10  20
RDM  57  90  51  81 /  30  20  10  10
LGD  52  93  59  80 /  20  20  30  20
GCD  57  92  56  81 /  30  20  30  10
DLS  77  92  66  81 /  20  20  10  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning until 10 PM PDT this evening for ORZ610-611-
     639>642-644.

     Heat Advisory until 8 PM PDT this evening for ORZ041-044-507.

     Red Flag Warning from noon to 11 PM PDT Saturday for ORZ640-
     642>645.

WA...Heat Advisory until 8 PM PDT this evening for WAZ024-026>029.

     Red Flag Warning from noon to 11 PM PDT Saturday for WAZ643-645.

&&

91/99/99/80

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PENDLETON OR
550 PM PDT FRI AUG 11 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0540 PM     HAIL             2 WNW MADRAS            44.64N 121.17W
08/11/2017  M0.50 INCH       JEFFERSON          OR   TRAINED SPOTTER

&&

PECK