Area forecast discussion 
National Weather Service Pendleton or 
230 PM PDT sun may 29 2016 


Short term...tonight through Wednesday...an upper level trough 
passing to the north but still impacting the forecast area will be 
exiting to the east overnight and Monday. Main impact is some breezy 
west winds through this evening. Could still be some isolated 
convective showers over northeast Oregon through early this evening. 
Ridge of high pressure will begin to build behind the departing 
trough which will bring a warming trend to the forecast area through 
Wednesday and beyond. High temperatures will be in the 80s and low 
90s by Wednesday. 


Long term...Wednesday night through Sunday...overview...very warm 
and dry conditions expected for the extended. The European model (ecmwf) which has 
been the outlying extended model over the past few days seems to be 
the model that is now panning out. The GFS, Canadian, and dgex all 
have trended towards this solution. So what does this mean? 
Thunderstorms have almost completely been removed from the forecast. 
There is a very minimal chance along the Washington Cascades on 
Thursday, but Thursday through Saturday is now forecast to be dry. 
There may be a need to add thunder over the central Oregon area but 
confidence is not high enough to add into the current forecast. With 
hot temperatures forecast for the extended from the Columbia River 
gorge to the Blue Mountain foothills, the lower Columbia Basin, and 
the Yakima Valley look to be approaching or even exceeding 100 
degrees on Sunday. 


Synopsis...the ridge of high pressure over the interior Pacific 
northwest that was more amplified on previous forecasts is now 
suppressed by a low pressure system off the Gulf of Alaska. This 
pulled down the high temperatures for Thursday and Friday into the 
upper 80s to lower 90s across the lower elevations, but as we move 
into the weekend the high pressure will amplify as a Four Corners 
high, with hot and dry southerly flow over the area. GFS and European model (ecmwf) 
both suggest highs to be near to over 100 degrees on Sunday. Models 
also develop a weak low pressure system off the California coast 
towards the weekend. This is where the thunderstorm threat could be 
tricky. There is some mid level moisture forecast over central 
Oregon on Saturday with the south flow ahead of the low. The 
question is, will there be enough instability or a trigger to set 
off convection. For now will leave central Oregon dry, but will 
continue to monitor and make adjustments accordingly. Sunday models 
are in decent agreement that enough moisture and instability should 
be present for thunderstorms over central and northeast Oregon, but 
will only go with slight chance until confidence grows with run to 
run continuity. Weber 




&& 


Aviation...00z tafs...VFR conditions forecast at all terminals 
through the taf period. Scattered-broken clouds 6k to 12k feet above ground level this 
afternoon and evening with gradual clearing trend at most terminals 
will occur after 30/06z. 


Winds at or below 12 kts through 29/15z. Then westerly winds quickly 
increase to between 15-25 kts region wide during the afternoon and 
early evening hours. Winds should gradually decrease after 30/06z 
back under 12 kts. Weber 




&& 


Preliminary point temps/pops... 
PDT 45 75 44 82 / 0 0 0 0 
alw 48 76 48 83 / 0 0 0 0 
psc 49 78 49 85 / 0 0 0 0 
ykm 45 78 46 84 / 0 0 0 0 
hri 47 78 46 85 / 0 0 0 0 
eln 44 75 46 82 / 0 0 0 0 
rdm 38 74 39 83 / 0 0 0 0 
lgd 42 70 41 77 / 10 0 0 0 
gcd 42 73 41 81 / 0 0 0 0 
dls 48 81 49 89 / 0 0 0 0 


&& 


PDT watches/warnings/advisories... 
or...none. 
Washington...none. 
&& 


$$ 


91/89/89 






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