Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 242129
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
230 PM PDT Mon Jun 24 2019

.SHORT TERM...Tonight through Thursday...A closed upper level low
pressure system off the west coast of Canada will drop south and
take up a position just off the Pacific Northwest coast on Tuesday.
This will turn our current westerly flow to southwesterly and
introduce some atmospheric instability that will translate into
showers and potential thunderstorms Tuesday afternoon and overnight.
By Wednesday the low will be along the Oregon coast and our flow
will be more southerly with even better instability and moisture
leading to more widespread showers and thunderstorms by afternoon
and overnight. Some of these showers and thunderstorms could produce
some brief heavy rainfall. On Thursday the low moves onshore and
begins to usher in cooler air and shift the better instability to
the east of the forecast. Still, there will be showers and some
thunderstorm potential but not as great as on Wednesday and mainly
over the eastern mountains.

.LONG TERM...Thursday Night through Monday...Thursday night a trough
will remain over the area with its central upper low on the west
side of the Cascades. After thunderstorms end in the evening, a
slight chance of showers will continue over the mountains and
central Oregon through Friday morning. Friday afternoon, the low
will be weakening and beginning to move northeast. A slight chance
to chance of showers will continue in the mountains and central
Oregon with the rest of the area dry. A slight chance of afternoon
and evening thunderstorms will be confined to the Ochoco-John Day
Highlands and from the Blue Mountains eastward. Friday night the low
will lift into British Columbia with a shallow trough lingering over
the area. Showers will taper off in the evening. Saturday through
Sunday will see the trough remaining but do not see much in the way
of moisture or disturbances so have a dry forecast. Sunday night and
Monday models diverge with the GFS and Canadian having a ridge over
us while the ECMWF has a weak low and trough over the area. Have
leaned towards the GFS/Canadian solutions and have kept the forecast
dry. Temperatures will be in a warning trend through the period.
Friday will be cool and below normal with highs in the 70s with 60s
in the mountains. Temperatures will then warm 3-5 degrees each day
ending up in the mid 80s to lower 90s with mid 70s to lower 80s in
the mountains next Monday. Perry


&&

.AVIATION...Previous discussion...18Z TAFs...Skies will be generally
clear through this evening aside from a few cumulus clouds over the
mountains and some high cirrus. As an upper low and trough slides
south along the coast later today and tonight, cloudiness will
increase with SCT-BKN mid and high level clouds above 7K feet AGL
developing after 08Z-12Z. No precipitation is expected for the next
24 hours though more unsettled conditions will begin to develop just
beyond the end of this forecast period Tuesday afternoon. KDLS will
have winds 10-17 kts with gusts to 25 kts through this afternoon
then will drop below 12 kts through tomorrow morning. Other TAF
sites will remain below 12 kts though KRDM and KBDN may have some
gusts to 20 kts from 21Z-04Z this afternoon. Perry


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  52  80  54  76 /   0  10  20  40
ALW  55  82  57  79 /   0  10  20  40
PSC  55  85  58  80 /   0   0  20  20
YKM  51  80  54  75 /   0  10  20  40
HRI  55  83  57  80 /   0   0  20  30
ELN  49  76  51  71 /   0  10  20  60
RDM  44  75  47  69 /   0  20  30  60
LGD  48  76  50  76 /   0  30  30  60
GCD  48  76  49  75 /   0  20  30  50
DLS  55  79  57  72 /   0  10  20  40

&&

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

$$

91/83/83


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