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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 162124

Area Forecast Discussion
National Weather Service Pendleton OR
224 PM PDT Sun Jun 16 2019

.SHORT TERM...Tonight through Wednesday...Main weather concern
during the short term period with be the breezy to windy
conditions and how winds will impact fire behavior for any new 
and existing fires. There is also a potential for winds to reach
advisory criteria in the Kittitas Valley and the Eastern Columbia
River Gorge Tuesday and Wednesday. A weak marine surge is already
causing 20-25 mph winds in the Eastern Columbia River Gorge. The 
marine layer west of the Cascades is quite shallow-- approx. 2800 
feet on the 12Z Quillayute sounding. However, the marine layer 
will deepen over the next 48 hours aiding in a stronger marine 
push by Tuesday. The high pressure ridge has flatten and increased
a westerly flow aloft this afternoon, along with the increasing 
onshore flow. From Monday through Wednesday, high pressure will 
strengthen between 130-140W and the Pacific NW will be on the east
side of the ridge and under a west-northwest flow aloft. Monday's
winds will be about the same or a little stronger than today. On 
Tuesday, an upper level shortwave and surface cold front will 
bring dry but windy conditions to many areas. At this time, it 
does not appear to be critical fire weather conditions due to the 
cooler temperatures and higher humidity. But, there are areas that
need to be closely monitored, particularly the Hanford District 
and Yakima Training Center. A strong westerly flow aloft and tight
pressure gradients on Wednesday will mean another day of gusty 
winds on Wednesday. The air mass will be dry above the boundary
layer despite the increasing surface humidity due to the strong 
marine push. Fire weather highlights may be in order for 
Wednesday, and this will be addressed in future discussions.

Towering cumulus have developed in the Blues and Wallowas this
afternoon but too shallow for any convection today. However, on
Monday, a shortwave traveling southeast will encounter some
instability in this area and may bring a few showers or
thunderstorms in Wallowa County. This was included in the
forecast. The remainder of the short term period will be dry.

.LONG TERM...Tuesday night through next Sunday...A dry and stable 
northwest flow will dominate at least the first part of the extended 
period through at least Friday. There will be weak disturbances in 
the flow which may bring clouds and breezy to windy conditions at 
times. There could be a few showers from time to time in the 
mountains. It will be too stable for least at the 
beginning of the extended period. The combination of wind and low 
humidity with very warm conditions may pose a fire weather threat at 
times and may possibly need highlights for fire weather hazards. By 
Saturday the long range models will differ more significantly from 
each other with one showing a ridge and another showing a closed 
upper low at the same time. During these times (the latter part of 
the extended forecast period) did not make too many changes due to 
the model uncertainty. It will remain warm and mostly dry with 
breezy to windy conditions at times. The chances for showers and 
possibly afternoon thunderstorms will increase by Sunday. It will be 
warm through Wednesday and then there will be a cool down into the 
70s to around 80 in the lower elevations for Thursday and Friday. 
Then it will warm up again back into the 80s for all lower 
elevations by Saturday and Sunday. 88


.AVIATION...12Z TAFs...VFR conditions will prevail during the next 
24 hours. Winds will be light, except they will become locally 
breezy this afternoon and early evening in the eastern end of the 
Columbia River Gorge and north central Oregon. 88


PDT  58  85  58  83 /   0   0   0   0 
ALW  61  88  60  87 /   0   0   0   0 
PSC  62  92  61  90 /   0   0   0   0 
YKM  60  89  58  85 /   0   0   0   0 
HRI  61  90  60  88 /   0   0   0   0 
ELN  57  80  58  75 /   0   0   0   0 
RDM  48  84  48  82 /   0   0   0   0 
LGD  54  82  53  81 /   0   0   0   0 
GCD  52  82  52  81 /   0   0   0   0 
DLS  59  82  60  79 /   0   0   0   0