Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 070325

Area Forecast Discussion
National Weather Service Pendleton OR
825 PM PDT Sat Jun 6 2020

.UPDATE...There were a few thunderstorms that developed over north
central Oregon a few hours ago and then tracked east to the Blue
Mountains and then suddenly dissipated. Other showers around the
forecast area are beginning to decrease now as well with the lost
of daytime heating. However, there still could be a shower or two
and cannot rule out a thunderstorm until sunset. Snow levels will
lower to around 4000 feet overnight. Otherwise next weather
feature of concern will be increasing winds with a strong jet
stream moving across the region on Sunday. When heating takes
place on Sunday this will allow mixing to cause strong winds aloft
to mix down to the surface, especially through the Cascade gaps
and in the Kittitas Valley where wind advisories are in effect
beginning at 8 AM Sunday morning and continuing until 2 AM Monday
morning. May potentially need to add other areas to the advisory
area such as the Blue Mountain Foothills, and may possibly need to
upgrade to a High Wind Warning in some areas if there is
indication that winds will get strong enough for a warning. Cannot
rule out a shower or possibly even a thunderstorm on Sunday as
well. Then on Monday the weather will settle down and become quiet
for the rest of the short term period, though still cannot rule
out a mountain shower from time to time, mainly due to heating
and orographic lift. 88


.AVIATION...06Z TAFs...VFR conditions will prevail for the next 24
hours. However, there will be isolated to scattered showers which
could cause MVFR for brief periods due to lower CIGS in rain
showers. Winds will increase on Sunday causing potential turbulent
conditions, especially for small aircraft, and especially in the
lee of the Cascade range such as at KDLS, KYKM, KRDM and KBDN
where mountain wave activity is most likely. 88


.PREV DISCUSSION... /issued 247 PM PDT Sat Jun 6 2020/

..Windy tomorrow, especially in Columbia Gorge and Kittitas

SHORT TERM...Today through Sunday night...Afternoon satellite
shows some decent cumulus field with some likely showers along the
east Cascade slopes. This afternoon, shower coverage will increase
to isolated, particularly along east Cascades, Central OR, and
other elevated areas of OR. A few of these may produce some
lightning or graupel considering low freezing levels. Showers will
ease this evening and shift east. A few lingering showers this
evening or overnight may be snow rather than rain for elevations
above 4000ft. Other than mountain residents, this is likely to
stay away from populated areas except for high elevations of US-97
south of La Pine. Overnight, gradients will tighten allowing winds
to remain elevated. Sunday, continued tight gradients, a well
mixed boundary layer, and some weak mountain wave-like activity
will promote downright windy conditions. Have issued wind advisory
to highlight potential for 50mph gusts in Kittitas and Gorge
regions. Winds will ease somewhat overnight though remain
elevated. Wind max will also shift east toward Blue Mtn foothills
though max winds may not necessarily meet highlight criteria.
Moisture will promote some continued showers again, especially
with the heat of the day. Again, a very slight chance of thunder
remains for the mountains. A drier airmass works it`s way in on
Monday leading to much lighter rain chances and commencing a
warming trend.

LONG TERM...Tuesday through Saturday...A low amplitude storm system
will be weakening as it moves across the region Tuesday and Tuesday
night...bringing just a few showers to mainly the mountains. On
Wednesday an upper level ridge will build over the area in advance
of an upper level low off the BC coast. This will result in mostly
dry conditions. Thursday and Friday look potentially interesting
from a thunderstorm standpoint. As the upper low/trough deepens
along the coast the mid-level flow will turn southwesterly and
increase. Low level moisture will be increasing as well with surface
dewpoints of 55-60F over central and eastern Oregon and extreme
southeast WA. This could set the stage for a round of strong storms
Thursday and Friday afternoon and evening. There will be a chance
for lingering showers on Saturday but the atmosphere will be more
stable. It will warm significantly from much below normal
temperatures Tuesday to near normal readings Wednesday through
Saturday. 78

AVIATION...00Z TAFS...VFR conditions will prevail through the
period...SCT-BKN cumulus/stratocumulus at 040-070 will become BKN-
SCT tonight. There will be some mid and high clouds above the lower
deck. Will carry VCSH at KBDN and KRDM late this afternoon and
evening. Winds of 12-25 kt with higher gusts late this afternoon
will tend to stay up overnight instead of the usual diurnal
decrease. Winds on Sunday will be 20-30 kt with gusts to 35 kt
especially after 18Z. Winds could gust to 40 kt at KDLS Sunday
afternoon. 78


PDT  45  63  46  66 /  20  30  20   0
ALW  46  65  46  68 /  20  30  30   0
PSC  50  71  50  73 /  10  10  10   0
YKM  44  69  44  70 /  10  10   0   0
HRI  48  68  49  70 /  10  10  10   0
ELN  44  63  45  64 /  20  10  10   0
RDM  35  57  35  64 /  40  40  20   0
LGD  42  55  42  61 /  60  70  40  10
GCD  39  53  38  62 /  80  70  40   0
DLS  48  64  50  68 /  20  20  10  10


OR...Wind Advisory from 8 AM Sunday to 2 AM PDT Monday for ORZ041.

WA...Wind Advisory from 8 AM Sunday to 2 AM PDT Monday for WAZ024-026.



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