Flooding in Washington, June 13 to 14, 2022

Area Forecast Discussion
National Weather Service Pendleton OR
500 AM PDT Mon Jun 13 2022

updated the aviation discussion

.SHORT TERM...Today through Tuesday...Overall, the forecast area
remains under the influence of an upper level trough with multiple
shortwave impulses moving through it. This trough will eventually
shift to the east and be replaced by a ridge of high pressure late
Tuesday.

The first of these systems impacted the forecast area yesterday and
overnight which is continuing to slowly lift into northern Idaho
this morning. Moisture wrapping around it will impact SE Washington
and northeast Oregon today with continued rain and showers with some
snow above 5000 feet. A second weaker shortwave is approaching the
coast in the northwest flow. This will move over the forecast area
this afternoon and evening helping to trigger some showers mainly
along the Cascade crest and eastern mountains. The northwest flow
will rain shadow the east slopes of the Cascades and out into the
Columbia Basin with little to no precipitation. A strong pressure
gradient will also accompany the shortwave producing some windy
conditions today along the Cascades east slopes and Columbia Basin.
Showers will decrease overnight before one last shortwave in the
form of a small closed circulation arrives on Tuesday passing over
the forecast area and exiting into southern Idaho in the late
afternoon and evening. This system will provide one last shot of
showers mainly over the mountains Tuesday with precipitation ending
by late afternoon. A ridge of high pressure will then begin to move
into the region from the eastern Pacific Tuesday night with skies
clearing and winds decreasing. Some high mountain valleys could see
some near freezing temperatures and frost Monday and Tuesday night.

Recent rain has brought many rivers to near bankfull with some still
possibly approaching flood stage before receding. Good news is that
precipitation amounts will now be lighter today and Tuesday which
decreases the overall potential for flooding. As such expect to
allow the overall flood watch for northeast Oregon and southeast
Washington to expire this morning. The flood watch for the lower
Grande River will continue as runoff over will continue over the
next couple of days as the river drainage continue to process the
recent rains.

.LONG TERM...Wednesday through Sunday. A ridge of high pressure will
bring mainly dry conditions to the area along with warmer
temperatures as afternoon highs climb into the 70s on Wednesday. The
EOF Variance appears to be in agreement however confidence seems to
decrease somewhat with the next weather system that is forecast to
effect the area Thursday and Friday and into the weekend.

A low pressure system over the epac is forecast to approach the two
state area Wednesday night and a few showers are possible along the
east slopes of the WA Cascades into Thursday. Some of the models
indicate some instability that may develop over our eastern portions
of the area Thursday afternoon. However the confidence appears low
at this time and will keep this pcpn free for now. Meanwhile the low
pressure system moves toward the Oregon coast Friday and showers are
expected to expand in coverage over our WA/OR cascades and migrate
further inland Friday afternoon. Also a few tsra are possible over
and near the Blue/Wallows mountains Friday afternoon and evening and
afternoon temps across the area will be a few degrees cooler than
the previous day.

The low pressure is forecast to slowly dip into N Cali Saturday and
becomes an elongated trough over the pacnw into Sunday. Showers are
expected to remain in the forecast for this weekend as temperatures
remain slightly below normal through the period.

&&

.AVIATION...a weather system will bring showers to some taf sites
this morning mainly taf site kpsc until 16z while taf sites kpdt and
kalw may experience showers throughout the day. Heavier showers
could make conditions approach lcl mvfr conditions. However mostly
vfr conditions can be expected. Meanwhile winds are expected to
increase and become breezy to windy with gusts between 25 to 35 kts
possible until 02z.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  64  45  67  44 /  30  10  20   0
ALW  62  47  67  47 /  90  20  20   0
PSC  69  50  73  49 /  40  10  10   0
YKM  66  43  69  44 /  10  10  10   0
HRI  68  47  71  46 /  10  10  10   0
ELN  58  43  61  43 /  10  10  10   0
RDM  61  36  65  37 /  10  10  10   0
LGD  54  41  58  39 /  40  20  30   0
GCD  55  38  60  37 /  20  20  20   0
DLS  65  50  70  48 /  20  10  20   0

&&

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

WA...Wind Advisory from 10 AM this morning to 8 PM PDT this evening
     for WAZ026.

&&

SHORT TERM...91
LONG TERM....97
AVIATION...97