Area forecast discussion...updated 
National Weather Service Pendleton or 
358 PM PDT Wednesday Oct 22 2014 

Updated aviation discussion 

Short term...tonight through Friday upper trough over 
the Gulf of Alaska and the eastern Pacific will keep the flow over 
the Pacific northwest west-southwesterly through Thursday. An upper 
level disturbance will push an associated cold front through the 
region tonight. As such, expect good chances of precipitation areawide 
during the tonight period. Winds will continue locally breezy over 
the mountains, the Grande Ronde Valley, the Wallowa valley and the 
Blue Mountain foothills prior to the frontal passage. A brief period 
of breezy winds may also accompany the frontal passage. On Thursday, 
expect showers to persist, especially near the Cascade crest and 
over the northeast Oregon mountains. There is just enough 
instability indicated over extreme northeast Oregon Thursday 
afternoon to warrant including a mention of thunder. The showers 
will wind down Thursday evening as high pressure aloft builds over 
the region in response to a southward digging of the offshore upper 
trough. The amount of expected digging by the trough has resulted in 
an expected slow down of the arrival of the next Pacific system. At 
this time still expect this next system's warm front to move north 
across the region, but with a slower timing. Thus will show the warm 
frontal precipitation mainly affecting our Oregon zones Friday and our 
Washington zones Friday night. Snow levels will remain above 5000 
feet through this entire period. 90 

Long term...Saturday through Wednesday...Saturday will begin mostly 
dry...except along the Cascades. However...breezy southerly winds 
can be expected of 15 to 25 miles per hour. Then as the upper trough and cold 
front move across the area late Saturday and Sunday...winds will 
shift westerly and surges of moisture will affect mainly the 
mountains. Snow levels will fall...but will remain above 4500 in 
Washington and above 5000 in Oregon so impacts will be minimal. 
Slightly drier conditions return Monday...but another upper level 
trough is expected to move across the area Tuesday and Wednesday. It 
is possible this trough may contain some leftover moisture and 
energy from tropical system Ana as it gets entrained into the 
westerly flow and merges with a middle-latitude system. However...the 
models do not agree well on the timing and intensity of the 
disturbance as it crosses the Pacific northwest. At this time there 
is confidence that unsettled weather will continue into the middle 
of next week...but it is uncertain how much precipitation will fall 
when and where. Cobb 


Aviation...00z tafs...mostly overcast skies will lower to near MVFR 
in rain tonight. Ceilings will begin to lift and showers will 
diminish on Thursday afternoon. Winds will be mostly out of a 
southerly direction and gusty at times. Winds will lessen some 
between 03z and 18z...then become 15 to 25 miles per hour and shift 
southwesterly around 20z. 82 


Preliminary point temps/pops... 
PDT 51 68 47 61 / 80 50 20 30 
alw 54 68 50 62 / 80 60 20 30 
psc 54 70 47 64 / 80 30 10 10 
ykm 46 63 41 59 / 90 20 20 20 
hri 51 70 46 63 / 70 30 20 20 
eln 46 63 39 60 / 100 20 20 10 
rdm 47 63 39 58 / 90 40 30 70 
lgd 54 62 47 58 / 70 70 40 50 
gcd 47 63 43 58 / 70 60 40 60 
dls 51 65 45 60 / 100 40 20 50 


PDT watches/warnings/advisories... 

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