497
FXUS66 KPDT 132122
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
222 PM PDT Thu Jun 13 2024

.SHORT TERM...Tonight through Saturday...The upper level ridge
pattern over the region today will be shifting to the east overnight
and Friday as a closed upper level low pressure system in the Gulf
of Alaska moves closer to Vancouver Island Friday. This will begin
to tighten the pressure gradient across the forecast area overnight
and Friday resulting in some increasing westerly winds. This will
mainly be noticeable along the east slopes of the Cascades late this
afternoon and into the evening before spreading east into the
Columbia Basin overnight providing some breezy conditions which
continue through Friday. A wind advisory has been issued for the
Kittitas Valley from this evening through Friday morning.


The closed upper level low will move over Vancouver Island Friday
night into Saturday. This will further tighten pressure gradients
across the forecast area increasing winds to 15 to 30 mph with gusts
30-40 mph on Saturday. These speeds would be slightly below advisory
level so at this point not considering an advisory but will see how
later model runs trend. The low will begin moving some moisture and
precipitation into Cascades mainly along the crest Friday night with
a 30-50% of showers which increases to 40-80% on Saturday. This
moisture will also clip NE Oregon and SE Washington with a low
chance of showers (15-30%) on Saturday.  The low will pass to the
east late Saturday allowing a drier flow to bring an end to the
showers overnight.

High temperatures will begin to cool slightly on Friday but will
become significantly cooler on Saturday with high temperatures
running 10 to 15 degrees cooler than normal.


.LONG TERM...Sunday through Thursday...A challenging start to the
forecast period as variations in model solutions starts early.
Variances in the track of an incoming of low pressure system leaves
a lack of strong confidence in any specific solution. The ensemble
clusters for Sunday and Monday highlight the track and strength
differences, though all agree that there will be precipitation at
some point during the late weekend/early week timeframe. The current
NBM solution introduces precipitation over the Cascades by Sunday
afternoon, with activity spreading eastward into central Oregon by
early Monday morning with the core of the system moving through the
forecast area by Monday afternoon. As the system progresses
eastward, there is an indication for wrap-around moisture to impact
the eastern half of the forecast area. This looks to produce
moderate chances (40-60%) over the Blue Mountains and slight to
moderate chances (20-40%) across the lower elevations through Monday
evening. Winds of 10-15 mph favored with this pattern, with locally
higher gusts.

Lingering moisture will leave showers possible (20-40% chance)
through Tuesday. Northwest flow moves over the region Tuesday
evening and remains through Thursday. Remaining moisture/instability
could produce a few showers or storms on Wednesday afternoon mainly
over the higher terrain (15-25% chance) with dry conditions then
generally anticipated through Thursday.

Impacts from the initial low pressure system will produce
temperatures that are 10-15 degrees below normal on Sunday and
Monday. Warmer values return to the region Tuesday through Thursday,
with values on Thursday returning to near normal to slightly above
normal values. The Columbia Basin is favored to have some of the
warmer temperatures on Thursday, with a 70-90% chance for
temperatures reaching 80 degrees (10-20% chance of reaching 90
degrees). Branham/76

&&

.AVIATION...18Z TAFs...VFR conditions through the TAF period. The
main aviation forecast challenge remains the development of gusty
wind this afternoon. The strongest winds of 15 kt with gusts to 25
kt are favored at KDLS, KRDM, and KBDN after 22z today. Wind will
stay gusty at KDLS through the TAF period, though KRDM and KBDN will
see calmer wind develop after 05z tonight. KPDT and KALW will see
gusty wind develop after 13z Friday producing  15 kt with gusts to
25 kt. Most other locations will see wind 12 kt or less. Branham/76


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  49  73  48  66 /   0   0   0  10
ALW  51  77  52  69 /   0   0   0  10
PSC  55  80  56  72 /   0   0   0  10
YKM  49  76  47  68 /   0   0   0  10
HRI  53  78  53  71 /   0   0   0  10
ELN  51  69  48  64 /   0   0   0  10
RDM  43  71  41  62 /   0   0   0   0
LGD  46  71  45  62 /   0   0   0  20
GCD  48  75  43  64 /   0   0   0  10
DLS  52  74  52  67 /   0   0   0  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...Wind Advisory from 8 PM this evening to 11 AM PDT Friday for
     WAZ026.

&&

$$

SHORT TERM...91
LONG TERM....76
AVIATION...76