821
FXUS66 KPDT 050510
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1010 PM PDT Fri Oct 4 2024

.UPDATED AVIATION...06 TAFs...VFR conditions expected through the
forecast period with the exception of lingering smoke at BDN
bringing CIGs to MVFR. Winds have begun to settle across the TAF
sites with all showing sustained at or less than 10 kts. Winds
will become calm and variable overnight. Bennese/90


&&

.PREV DISCUSSION... /issued 906 PM PDT Fri Oct 4 2024/

EVENING UPDATE...Red flag conditions are finally behind us,
though some breezy winds do remain. Thankfully relative humidity
values have significantly risen to help alleviate critical fire
weather conditions, and winds will continue to lessen through
tomorrow morning allowing for a relatively calm weekend. Outside
of the red flag warnings dropping alongside the brief blowing dust
advisory in the Grande Ronde Valley, no major changes to the
afternoon forecast package aside from some temperature
adjustments. Goatley/87


PREV DISCUSSION... /issued 239 PM PDT Fri Oct 4 2024/

SHORT TERM...Tonight through Sunday night...Satellite and radar
show a well defined cold front with a distinct back edge across
the eastern WA Cascades then extending to the southwest from The
Dalles to Coos Bay. There is a narrow band of cloud cover and
light precipitation ahead of the front. Of course, any
precipitation in our forecast area will not last long and any
rainfall amounts will be very light over the next several hours.
Winds have increased with widespread gusts 25-35 mph throughout
the Columbia Basin down to Central Oregon as well as the Grande
Ronde and John Day Valleys. Winds have stirred up blowing dust
this afternoon. So far, no reports of any significant reduction
in the visibility with the exception of KLGD. Looking at web cams
in the Grande Ronde Valley, the 2-3 mile visibility seems
localized to the airport.

Red Flag Warnings are in effect until 7 PM for the John Day Basin
and John Day-Ochoco Highlands as well as far southeast Washington
along the Grande Ronde Valley of Asotin County. The warning was
extended to include Central Oregon near Bend, Redmond, and
Prineville. Although the RHs have increased in Central Oregon this
past hour, RHs fell near the single digits earlier this afternoon
as the winds increased which warranted the extension of the Red
Flag Warning.

Winds will diminish tonight and skies will clear, giving good
opportunities to view the aurora borealis...if it decides to make
an appearance...with best viewing in Washington. According to
Space Weather Prediction, there is a GS watch through October 6.
The rest of the short term looks quiet. High pressure will return
tomorrow, and the inverted surface thermal trough strengthens some
along the Cascades. The thermal trough shifts eastward on Sunday
as the upper flow increases more from the southwest. It will be
warmer with lower humidity and slightly more unstable conditions
on Sunday. However, winds will be relatively light and no
critical RH values are anticipated. Looking at LREF ensembles, the
probability of RHs falling below 20% is very low with the
exception of south central and southeast Oregon with high
confidence that minimum RHs will range from 15-20% and moderate
confidence for 10-15%. Wister/85

LONG TERM...Monday through Friday...

The upper ridge will remain over the PacNW through Wednesday
afternoon as it slowly continues moving east from the region. The
westerly flow progresses over the forecast area Monday into Tuesday
afternoon with fairly light winds at 12 mph or less and dry
conditions (>70% confidence). Tuesday through Wednesday, the flow
will then change to southwest as a weak cold front makes its way
into the area. Due to orographic lifting, showers could occur at
the WA/OR Cascades. However, confidence is low due to lack of
moisture.

Thursday, the ridge starts breaking down as the shortwave trough
begins arriving to the PacNW off the OR coast. With increased
southwest flow and a cold front, showers could return Thursday
night at the WA/OR Cascades, and then across the Foothills
including some portions of central OR (15-30% chance). Breezy
conditions might also develop at the Kittitas and Yakima valleys
including Ochoco-John Day Highlands up to 20 mph. The probability
of wind gust>= 17kts is 10- 20% for the valley zones and 30-50%
for the Ochoco-John Day Highlands, suggested by NBM.

Friday, the shortwave trough will be over the forecast area. As the
cold front passes, gusty winds and showers could develop due to
orographic lifting and moisture advection (15-30% chance). The
probability of 10-m Wind Gust>= 17kts for the WA Cascades, central
OR and Foothills will be 30-60%. High temperatures will remain above
normal through the period. Feaster/97

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  38  69  40  72 /   0   0   0   0
ALW  43  71  42  74 /  10   0   0   0
PSC  43  70  42  73 /   0   0   0   0
YKM  35  69  37  72 /   0   0   0   0
HRI  40  71  41  74 /   0   0   0   0
ELN  38  69  39  74 /  10   0   0   0
RDM  33  74  38  81 /   0   0   0   0
LGD  37  71  41  79 /  20   0   0   0
GCD  37  75  44  82 /   0   0   0   0
DLS  43  74  46  78 /  10   0   0   0

&&

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

$$

EVENING UPDATE...87
SHORT TERM...85
LONG TERM....97
AVIATION...90