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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 170517 AAA

Area Forecast Discussion
National Weather Service Pendleton OR
1020 PM PDT Tue Apr 16 2019

Updated Aviation Discussion

.SHORT TERM...A weak flat ridge extends from the eastern Pacific
to the Rockies, and a westerly flow is over the forecast area. A
shortwave is riding over the ridge and bringing widespread
precipitation across western WA and northwest OR with slopover to
the eastern slopes of the Cascades. Although models keep
precipitation mainly as orographic mountain showers along the
Cascades, Blue Mountains and Wallowas, WSR-88D is showing
increasing returns at the 0.5 degree slice across south central
WA and north central OR. Forecast was updated to show isolated
evening showers or sprinkles across the Columbia Basin down to
north central OR. As the ridge strengthen overnight and Wednesday
morning, precipitation will lift northward with dry conditions in
the afternoon. Afternoon temperatures on Wednesday will be in the
mid-50s to around 70--about 5 to 10 degrees warmer than today. 
Hydrology concerns are getting less and less each day, but 
continued snowmelt runoff will still pose a problem for high 
waters and fast flowing rivers and streams. Wister


.AVIATION...06Z TAFs...VFR conditions for the next 24 hours with 
varying cumulus and altocumulus clouds.  CIGS AOA 5K feet AGL for 
the next 24 hours.  Isolated showers this evening should be 
very light with no significant impact on CIGS and VSBY at the 
TAF sites. Winds will be light tonight and increase to 5-15 
knots with gusts to 20 knots on Wednesday.  Wister


.PREV DISCUSSION... /issued 141 PM PDT Tue Apr 16 2019/ 

SHORT TERM...The ridge will intensify enough late Wednesday and 
Thursday to keep precipitation west and north of the forecast 
area. We will see warming temperatures through Thursday with highs
approaching 80 in the lower Columbia Basin by Thursday. The ridge
will break down Friday and allow a cold front to sweep through 
the region and bring some precipitation back into the forecast 
area and cool temperatures. 

LONG TERM...Friday night through Tuesday. Long term begins with a 
cold front continuing to drop south and east of the region Friday 
evening with showers over the mountains and Central OR dissipating 
through the night. Gusty winds during the evening hours will 
decrease through the night. Mainly dry and cooler conditions 
expected over the weekend with ridging building in behind the cold 
front. Next chance for precip looks to be early to mid next week as 
the pattern looks to become more westerly zonal, allowing for an 
increase of Pacific moisture and cloudiness over the PacNW. While 
there looks a be a chance for a few showers Monday and Tuesday as a 
couple of weak waves move through the upper flow, but looks like the 
better chance for precip will be towards mid-week with a more 
energetic short-wave approaching. Model consensus is rather poor for 
next week, so leaned towards the GEFS ensemble mean. Expect cooler 
but still seasonable temps behind the front with highs in the upper 
50s to 60s and lows in the mid 30s to mid 40s for the weekend into 
early next week.

Snow melt from daytime highs in the upper 50s and 60s in the Blues 
Thursday and Friday coupled with additional rainfall (potentially up 
to half an inch) Friday afternoon/evening will yield an additional 
bump up on many rivers, creeks and streams draining the Blues but at 
this time only the John Day River at Service Creek and the Grande 
Ronde at Troy are expected to rise above flood stage. 


PDT  45  66  46  76 /  10  10   0   0 
ALW  45  68  47  76 /  20  10   0   0 
PSC  49  72  48  79 /  20  10   0   0 
YKM  43  70  46  76 /  20  10   0   0 
HRI  47  71  49  79 /  10  10   0   0 
ELN  42  62  43  71 /  20  10   0  10 
RDM  37  66  43  76 /  10  10   0   0 
LGD  38  58  40  71 /  20  20   0   0 
GCD  36  62  41  73 /  10  10   0   0 
DLS  45  67  47  77 /  20  10   0   0