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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 201520

Area Forecast Discussion
National Weather Service Pendleton OR
820 AM PDT Tue Aug 20 2019

.SHORT TERM...Today and tonight...One more day under a ridge of high 
pressure which will provide warmer then normal temperatures and 
mostly clear skies today. Will start to see some increasing clouds 
overnight from an approaching upper level trough that will push a 
cold front through the forecast area on Wednesday. This cloud cover 
will help provide warmer than normal temperatures for overnight too. 
Overall winds will be light with just some usual breezy conditions 
through the Columbia River Gorge this afternoon.  


.PREV DISCUSSION... /issued 310 AM PDT Tue Aug 20 2019/ 

SHORT TERM...Today through Thursday night...SW flow aloft will be 
over the area for one more day resulting in hot afternoon 
temperatures under mostly clear skies. High temperatures will be in 
the 90s with 80s in the mountains. An upper level trough will 
approach the area Wednesday and swing across the region Wednesday 
night. This will move a strong cold front across the forecast area 
late in the day into the evening. Main impacts from this front will 
be a burst of gusty winds and a few rain showers. Winds could gust 
in excess of 30 mph with the front and perhaps a bit stronger in a 
few locations. However do not think there will be a prolonged wind 
advisory event. Models are trending a little wetter with the front 
and have at least some chance of showers over the entire forecast 
area. QPF amounts look light. Airmass does not appear to be 
supportive of thunderstorms so have left mention of thunder out of 
the forecast. By Thursday the upper trough is east of the area and a 
cool northwest flow aloft takes over. Highs on Thursday will be in 
the upper 70s to mid 80s in the lower elevations with upper 60s to 
mid 70s in the mountains. It will be cool Thursday night with lows 
50-55 in the lower elevations and upper 30s to mid 40s mountains and 
high plateaus. 78 

LONG TERM...Friday through Tuesday...Models in good agreement 
through Sunday, but begin to diverge thereafter.  Dry northwest flow 
aloft will continue at least into Sunday.  Some weak embedded 
shortwaves in the northwest flow will produce a short-lived increase 
in cloud cover.  Otherwise, the tranquil weather will continue.  By 
Sunday night, the new run of the ECMWF shows an upper level low 
diving out of BC and clipping our northeast CWA by Tuesday. 
Meanwhile, the GFS continues the dry, west to northwest flow aloft. 
At this time, will lean towards the more persistent GFS solution and 
keep the weather dry.  Daytime temperatures will remain near to 
slightly above normal through the period. Earle

AVIATION...12Z TAFS....VFR conditions are expected through the 
period with only thin cirrus moving through the area.  Winds 
will generally be 10 kts or less with higher gusts possible during 
the afternoon, except KDLS will increase to 12-16 kts by afternoon 
with higher gusts.  Winds will decrease overnight to less 
than 8 kts.  Earle


PDT  93  62  88  55 /   0   0   0  30 
ALW  95  63  90  60 /   0   0   0  20 
PSC  95  62  90  59 /   0   0  10  30 
YKM  93  58  83  52 /   0   0  40  30 
HRI  95  63  90  54 /   0   0  10  30 
ELN  92  57  81  54 /   0   0  40  30 
RDM  92  52  87  44 /   0   0  20  40 
LGD  93  55  90  52 /   0   0   0  30 
GCD  93  58  92  54 /   0   0   0  20 
DLS  92  61  79  57 /   0   0  40  40