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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 171518

Area Forecast Discussion
National Weather Service Pendleton OR
818 AM PDT Sat Aug 17 2019

.UPDATE...A weak disturbance will track to our north but some mid
and high level clouds will pass through the region today.
Otherwise the dry conditions will continue and afternoon high
temps are forecast to climb into the 80s with 70s in the


.PREV DISCUSSION... /issued 210 AM PDT Sat Aug 17 2019/ 

SHORT TERM...Today through Monday night...A northwest flow will 
prevail over the region and the forecast area today and tonight with 
an upper trough over the northern Rockies and a high pressure system 
over the Pacific, about 950 miles off the Oregon coast. This will 
keep dry and stable conditions over the forecast area. Temperatures 
today will be similar to Friday with maximum readings a little below 
normal due to the cooler northwest flow. High temperatures today 
will be in the mid to upper 80s in the lower elevations and mostly 
70s in the mountains. These are just a couple degrees below normal. 
The flow will then back and become more westerly and eventually 
southwest by Sunday and Monday. Even though a southwest flow usually 
means more instability and increasing moisture, there just is not 
that much moisture to be pulled into the PacNW. As a result 
conditions will remain dry. However, it will be a little warmer due 
to the flow having a more southern origin. Temperatures will rise 
back to become slightly above normal with max readings in the upper 
80s to around 90 by Sunday and Monday in the lower elevations and in 
the mid 70s to mid 80s mountains. Precipitation is not expected 
anywhere in the forecast area through the entire short term forecast 
period (through Monday night). It will become locally breezy in the 
afternoons and evenings through the Cascade gaps and the eastern 
Columbia River Gorge. Elsewhere winds will be mostly diurnally 
terrain driven. 88

LONG TERM...Tuesday through Friday...A southwesterly flow aloft 
with dry weather and hot temps to start the long term, climbing into 
the upper 80s to mid/upper 90s for Tuesday and Wednesday. Models 
begin to diverge a bit towards late week, but the overall general 
trend is for an weakening upper-level trough to swing through the 
PacNW Thursday, with the flow then turning more zonal to northwest 
next weekend. Not overly deep moisture push with trough passage and 
for now only looking for potential of a few mountain showers, mainly 
over the WA Cascades later Wednesday into Thursday, with dry 
westerly flow out in the Columbia Basin. Another weak trough could 
swing through over next weekend, with a few showers possible again 
for the WA Cascades. Cooler, more seasonable temps expected behind 
the initial trough/frontal passage with highs in upper 70s to around 
90 on Thursday through Saturday. There will be occasional breezy 
periods with marine pushes mainly Wednesday and Friday evening... 
with the strongest wind in the Kittitas Valley and Columbia Gorge. 

AVIATION...12Z TAFs...VFR conditions through the period with 
increasing high cirrus. Winds will be a bit less than yesterday 6- 
14kts, still a little stronger at DLS 10-18g20-24kts. Winds will 
decrease overnight.


PDT  82  52  87  55 /   0   0   0   0 
ALW  86  57  90  59 /   0   0   0   0 
PSC  87  58  90  60 /   0   0   0   0 
YKM  86  53  89  55 /   0   0   0   0 
HRI  87  55  90  58 /   0   0   0   0 
ELN  83  54  86  54 /   0   0   0   0 
RDM  82  48  89  50 /   0   0   0   0 
LGD  80  52  88  54 /   0   0   0   0 
GCD  85  51  93  53 /   0   0   0   0 
DLS  83  59  88  60 /   0   0   0   0