Area Forecast Discussion
Issued by NWS Pendleton, OR

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293
FXUS66 KPDT 240524
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1025 PM PDT MON MAY 23 2016

updated aviation discussion

.SHORT TERM...Tonight and Tuesday...Overall the Pacific Northwest
continues under a trough pattern with multiple shortwaves moving
trough the trough. Strongest one is over southern Canada which is
sending some moisture back into eastern Washington but just clouds
over the forecast area this evening. Otherwise there continues to be
a few lingering evening instability showers over central Oregon that
are coming to an end now that the heating of the day is over. The
other shortwaves are south and west of the forecast area which will
help drive the trough deeper into California overnight and Tuesday.
With the trough continuing to linger over the region Tuesday we
will again see some afternoon and evening instability showers mainly
over the mountains. Some of these could become thunderstorms over
far eastern and southern Oregon.

.AVIATION...06Z TAFS...VFR conditions will prevail through the
forecast period. SCT mid clouds with cirrus above can be
expected overnight then some possible afternoon showers over and
near the moutnains. Winds will be 5-15KT peaking Tuesday afternoon.

&&

.PREV DISCUSSION... /issued 232 PM PDT MON MAY 23 2016/

SHORT TERM...Tonight through Thursday...An upper level trough will
linger over the western U.S. tonight through Wednesday. Weak
disturbances will rotate through this trough causing varying chances
of showers. The best chances of showers will occur in the afternoons
and evenings. Instability during the afternoon into the early
evening Tuesday and Wednesday could be strong enough over for a few
thunderstorms. Thunderstorms will mainly occur over our eastern
mountain zones. Winds will be locally breezy through Wednesday,
especially through the Kittitas Valley and the Columbia River Gorge.
Another upper low will begin to move south through British Columbia
Thursday. This low will produce an increase in the west flow across
the region. As a result, will see winds across the area increase
with the winds in the Kittitas Valley and the Columbia Gorge
potentially reaching advisory speeds of 30 to 35 mph sustained.
Expect mainly dry conditions Thursday, though a few showers may
occur near the Cascade crest, and over the Blue mountains and
Wallowa county. Temperatures will run near seasonal through this
period. 90

LONG TERM...Thursday Night through Monday...Models in good
agreement in overall longwave pattern over the region. However...
there are temporal and spatial disagreements relating to the next
upper level system dropping down from Canada on Friday. GFS evolves
it into a cutoff low while the ECMWF is more progressive. At this
time...will lean more towards the GFS solution as the overall
pattern lends itself to producing cutoff lows. Overall...the
forecast area will be dominated by a troughy weather pattern through
much of the extended. As a result of the expected pattern...
unsettled weather will continue with showers forming in the
afternoon and dissipating overnight...especially over the northeast
Oregon. Daytime highs will be near to slightly above normal through
the period. Earle



&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  47  71  49  74 /  10  10  10  10
ALW  51  73  53  74 /  10  10  10  10
PSC  51  77  54  81 /  10  10  10  10
YKM  46  76  50  80 /  10  10  10  10
HRI  49  76  52  79 /  10  10  10  10
ELN  48  72  53  74 /  10  20  10  10
RDM  36  67  39  69 /  20  10  10  10
LGD  41  66  44  69 /  10  20  30  30
GCD  40  67  42  70 /  20  20  20  20
DLS  52  75  54  72 /  10  10  10  10

&&

.PDT Watches/Warnings/Advisories...
OR...None.
WA...None.
&&

$$

91/91/91



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