662
FXUS66 KPDT 131120
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
230 AM PDT Mon May 13 2024

.SHORT TERM...Today through Wednesday...An upper level shortwave
trough will pass over the region today producing breezy to windy
conditions but very little if any precipitation. Sustained winds of
15 to 30 mph with gusts around 40 mph will be common throughout the
lower elevations. The Kittitas Valley is expected to see a little
stronger winds with gusts 45 to 50 mph so a wind advisory is in
effect through this evening. The winds will usher in some cooler
air with high temperatures running 5 to 15 degrees cooler today
compared to Sunday.

The trough will exit to the east overnight with a ridge of high
pressure in its wake building over the eastern Pacific Ocean. This
will keep the forecast area under a dry northwest flow Tuesday
through Wednesday with lighter winds. Temperatures will remain
steady to slightly warmer on Tuesday and then rise another 5
degrees or so on Wednesday.

.LONG TERM...Thursday through Monday...Not much of a change to the
forecast through the long term. Temperatures remain steady with dry
conditions continuing  through the lower elevations. There continues
to be below 15% probabilities of rain along the far northern
Cascades and increasing to 22-36% probabilities Sunday into Monday.

Models are in firm agreement with the upper level high shifting
slightly southwest away from shore and broadening the upper level
flow as an upper level shortwave moves down the coast of B.C..
Clusters shows there is a timing and positioning variance between
the models however. Both Thursday and Friday have signaled an
increase in the cross Cascade pressure gradient which will increase
the chances of westerly flow and windy conditions beginning in the
Kittitas Valley and progressing southward through the day. Latest
raw ensembles shows there is 20-30% chance of the Gorge and lower
Columbia Basin seeing sustained winds of 25 mph, 40-60% along the
Simcoe Highlands and through Kittitas Valley. These chances increase
to 30-40% through the Gorge and lower Columbia Basin and Kittitas
Valley and 40-60% along the Simcoe Highlands. Confidence in the
winds in moderate with the timing being the largest variance. EFI is
showing a slight increase in above normal temperatures mainly
through the Basin with the NBM putting temperatures in the upper
80s. Over 70% of the raw ensembles put the entirety of the Columbia
Basin, Gorge, foothills of the Blues and John-Day Basin above 80
degrees dropping to the upper 70s to low 80s by Friday. The
shortwave passage also brings a less than 15% probability of rain to
the higher elevations of the far northern Cascades near Snoqualmie
Pass.

Saturday and Sunday confidence between the models lessens a bit more
with the timing and the strength of the upper level low. EURO shows
the shortwave to broaden bringing increased chances of rain while
the GFS tightens into an upper level low with precipitation locked
against the Cascades.  Models also show a surface embedded cold
front ahead of the upper level system which will bring a decrease in
the temperatures Saturday. EFI shows the temperatures Saturday and
Sunday to moderate to near normal with 70-80% of the raw ensembles
showing the aforementioned areas dropping nearly 10 degrees Saturday
steadily increasing Sunday. Guidance shows the winds to shift to a
more northwesterly component allowing diurnally breezy conditions
with 70% probabilities for the more wind prone regions to see near
20 mph winds.

Lastly, models fall out of phase by Monday with the Euro bringing in
a brief transient ridge ahead of another upper level low while the
GFS keeps the original low overhead and deepening across the region.
With that, let the NBM take the reins which has 22-36% probabilities
of rain along the northern Cascades , light westerly winds and
temperatures in the upper 70s for the lower elevations. Bennese/90



&&

.AVIATION...12Z TAFs...VFR conditions through the forecast period.
Li and there will be more cumulus with similar bases on Monday.
Lingering high level cirrus around 18+ kft will fluctuate across
eastern WA and northeast OR during the day. It has been breezy for
DLS overnight while under 10kts elsewhere. However, westerly winds
of 10-15 kt gusting to 20-35kt will ramp up across the remaining TAF
sites between 17Z & 21Z. Bennese/90

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  75  48  74  49 /   0   0   0   0
ALW  78  51  76  53 /   0   0   0   0
PSC  82  53  81  54 /   0   0   0   0
YKM  78  46  81  49 /   0   0   0   0
HRI  80  50  80  51 /   0   0   0   0
ELN  70  49  76  51 /   0   0   0   0
RDM  72  41  73  44 /   0   0   0   0
LGD  73  44  72  45 /   0   0   0   0
GCD  74  42  73  44 /   0   0   0   0
DLS  74  50  81  54 /   0   0   0   0

&&

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

&&

$$

SHORT TERM...91
LONG TERM....90
AVIATION...90