Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 272215 AAA
AFDPDT

Area Forecast Discussion...UPDATED.
National Weather Service Pendleton OR
415 PM PDT Wed May 27 2020

.SHORT TERM...Tonight through Saturday. Upper ridge over the
region with a dry westerly flow aloft. Satellite imagery indicates
some cirrus moving through overnight. Several degrees warmer today
however dew points have decreased significantly. For the most part
expect lows to be in the 40s tonight. The upper flow turns more
southwesterly Thursday combined with the surface thermal trough
moving into the region. This will increase the instability over
southern and central Oregon. Could have isolated thunderstorms
develop late afternoon into early evening over the Oregon Cascades
to the John Day highlands. Coverage would be fairly minimal if
storms develop and they would likely diminish after sunset. Temps
will be several degrees warmer with highs in the 80s. The upper
low will near the California coast on Friday. Better instability
over Oregon and expect more coverage of thunderstorms in the
afternoon and evening. Dynamics are still weak as the low and jet
are well to the south. These would be more pulse type storms.
Friday will be the hottest day with highs in the 80s to lower 90s.
The low will move into northern California on Saturday with a
strong jet crossing the forecast area. Showers and thunderstorms
are likely. May have some stronger storms with heavy rain this
day.  94

.LONG TERM...Saturday night through Wednesday. The primary
sensible highlights include a cooler turn in temperatures compared
to the short term period (albeit highs leaning near to slightly
warmer than normal for this time of year) and more or less
periodic precip chances. Precipitation from the system at the
start of the period expected to be tapering off with respect to
coverage and chances with possible lingering showers Sunday.
Otherwise, unsettled conditions Monday and beyond with slight
chances-chances for showers and isolated thunderstorms, higher
chances across central OR and Blue Mountains/northeast mountains.

Deterministic guidance and ensembles in fair agreement at the start
of the long term with an upper level trough over the northeast
Pacific and the main shortwave trough lifting north across the
Pacific Northwest and Columbia Basin Saturday night. The upper
trough lifts northward into northern Alberta by Sunday night while
the next upper level trough evolves offshore the West Coast. Current
thinking is Sunday could be drier than forecast with highs
anticipated to be 5-10 degrees or so cooler than Saturday. Monday on
then start to see more differences in phase and amplitude with the
aforementioned upper-level trough upstream. The influence of the
upper trough, offshore or on the West Coast, will then be seen
through early next week promoting the previously said precip
chances. 80

&&

AVIATION...00Z TAFS...VFR conditions will continue through the TAF
period. Visible satellite imagery shows sunny skies with some
cirrus. Mostly clear skies will prevail through early tonight. High
clouds will then increase late tonight and will persist tomorrow.
Winds are currently light and mainly out of the north with light
winds continuing tonight followed by increasing north/northeast
winds tomorrow. 80

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  46  85  56  91 /   0   0  10  10
ALW  48  86  58  90 /   0   0   0  10
PSC  49  88  56  94 /   0   0   0  10
YKM  48  86  55  92 /   0   0   0  10
HRI  47  88  56  94 /   0   0   0  10
ELN  45  84  52  90 /   0   0   0  10
RDM  44  85  51  89 /   0   0  10  20
LGD  43  82  54  85 /   0   0  10  20
GCD  45  85  55  88 /   0  10  20  20
DLS  51  88  57  93 /   0   0   0  10

&&

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

$$

94/80/80


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