Area Forecast Discussion
Issued by NWS Pendleton, OR

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FXUS66 KPDT 202123
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
223 PM PDT Wed Sep 20 2017

.SHORT TERM...Tonight through Saturday...An upper level low is
moving over southeastern WA this afternoon. The associated trough
is digging offshore because a vort max is moving down the backside
of the trough. Another vort max is moving over WA/OR this
afternoon. The colder air aloft from the low and dynamic lift from
the second vort max has triggered a few thunderstorms this
afternoon. The first vort max will move into central CA tonight
and elongate the trough along the coast. This will keep northerly
flow and showers over the mountains in eastern WA and OR tonight.
The upper part of the trough will shift slowly east Thursday
while an upper level low forms in the southern part. Moisture and
instability rotating around this low will keep showers in the
mountains Thursday night. Showers will linger in the central OR
mountains to Wallowa County Friday as this low moves slowly east.
Saturday a ridge will build offshore with drier northerly flow
developing in eastern WA and OR. Temperatures will increase each
day as the upper level low moves out and warmer air aloft moves
into the CWA. Coonfield

.LONG TERM...Saturday Night through Wednesday...Sunday night an
upper trough will move east into Montana and Utah and an offshore
ridge will expand over the Pacific Northwest. The ridge will remain
the dominant feature through the long term period this will lead to
dry weather with a warming trend. The ridge axis will remain
offshore through Monday with a few disturbances riding over the
ridge into Canada. The main impact will be partly cloudy skies at
times. Winds will be generally under 10 mph through the period.
Temperatures on Sunday will be in the 60s and lower 70s then will
warm to the mid 60s to mid 70s on Monday. On Tuesday, the ridge axis
will move overhead and temperatures will warm to the upper 60s and
70s. By Wednesday the ridge axis will move into Idaho but our area
will remain warm with highs in the 70s to around 80. Perry


&&

.AVIATION...00Z TAFs...An upper level trough will continue to send
partly to mostly cloudy skies and unsettled weather across the area
this evening. Conditions will be mainly VFR, though MVFR CIGs and
visibilities may occur with some moderate rain showers and or
thunderstorms at times through around 03Z this evening. Thunderstorm
activity will be too limited to mention at any TAF site. After 03Z,
cloud cover will be more scattered and rain showers will be mainly
confined to the mountains through 00Z tomorrow afternoon. Winds at
KRDM, KBDN, KPDT, KALW and KDLS will continue at 10-20 kts with
gusts to 25 kts this evening then decrease to below 12 kts by 05Z.
Otherwise, winds will remain below 12 kts through 00Z tomorrow
afternoon. Perry

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  41  58  41  62 /  40  10  20  10
ALW  45  60  45  63 /  40  20  20  10
PSC  44  65  44  68 /  20  10  10  10
YKM  38  62  44  68 /  20  10  20  10
HRI  43  63  43  67 /  20  10  10  10
ELN  40  62  42  67 /  20  20  20  10
RDM  30  54  33  59 /  30  20  20  10
LGD  36  53  36  58 /  60  30  30  20
GCD  37  52  36  56 /  60  20  20  20
DLS  48  65  48  72 /  30  20  10  10

&&

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

$$

76/83/83



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