Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 201003

Area Forecast Discussion
National Weather Service Pendleton OR
303 AM PDT Sat Apr 20 2019

.SHORT TERM...Today through Monday night. Showers continue across
much of the forecast area early this morning with strong upper
level trough moving into the Pacific northwest. Heaviest 
precipitation remains over central and northeastern Oregon. The
trough will slowly move across the region today. Little change to
the overall pattern through the morning with showers continuing 
especially over central and northeast Oregon. This area has 
received a fair amount of rainfall. With additional rain today 
amounts will likely be 1/2 to 1 inch for many locations. Already 
seeing some rises on rivers and streams and expect this will 
continue through the day. By afternoon the precipitation will be 
moving further east toward the Idaho border. Central Oregon 
northward to the Yakima valley and into the Washington Columbia 
basin should have decreasing clouds and rain at this point. Upper 
ridge builds into the area Sunday with mostly sunny skies and 
warmer temperatures. The ridge remains in place Monday however a 
warm front will be moving through with increasing mid and high 
level clouds. 94

.LONG TERM...Tuesday through Saturday...A ridge will remain over the 
forecast area through most of the long term period though a few weak 
disturbances will cross over the ridge and through the area. On 
Tuesday and Tuesday night one disturbance will be crossing the area 
and flattening the ridge. This will bring a chance of showers along 
the Cascade crest and a slight chance of showers to the northern 
Blue Mountains and northeast Oregon. The rest of the area will be 
dry. Precipitation amounts will be just a few hundredths of an inch. 
Snow levels will be 8000-9000 feet though it will drop to around 
6000 feet behind the system. A slight chance of light upslope 
showers will continue Wednesday over the Cascade crest and eastern 
Oregon mountains. By Thursday the ridge axis will shift east into 
western Idaho and then into eastern Idaho and Montana on Friday. 
Wednesday night through Thursday night will be generally dry aside 
from a slight chance of rain showers over northeast Oregon Thursday 
afternoon. The GFS is hinting at some instability but held off on 
added a slight chance of thunderstorms for now. On Friday, the GFS 
brings a system into the area on a southwest flow that would favor 
thunderstorms while the ECMWF keeps a dry northwest flow over the 
area. Went with a slight chance of showers along the Cascade crest 
and over the northeast Oregon mountains but again held off on 
mentioning thunderstorms until better agreement is seen in the 
models. On Saturday, the GFS continues to have a more moist 
southwest flow and the ECMWF turns more to the west. Once again have 
a slight chance of showers along the Cascade crest and from the Blue 
Mountains eastward. Temperatures will start out Tuesday in the mid 
60s to mid 70s then cool a degree or two each day ending up in the 
mid 50s to mid 60s by Saturday. Perry


.AVIATION...Previous discussion...06Z TAFs...An area of ra extends 
from BDN newd to ALW and covers a large portion of Nern OR and a 
small portion of sern WA. Most of the guidance has this rain 
dissipating or lessening overnight before additional rain moves in 
during the mrng. The latest guidance also now brings MVFR CIGS for 
PDT, BDN, RDM and ALW. Conditions will improve to VFR everywhere 
later Saturday afternoon as an upper trough/cdfnt cross the region, 
rainfall comes to an end and the sky begins to clear out. 77


PDT  62  40  64  40 /  70  20   0   0 
ALW  62  43  66  43 /  70  20   0   0 
PSC  68  42  71  43 /  30  10   0   0 
YKM  68  40  70  42 /  10  10   0   0 
HRI  67  42  70  43 /  40  10   0   0 
ELN  63  38  65  40 /  10  10   0   0 
RDM  58  33  62  35 /  70  20   0   0 
LGD  54  39  59  35 /  80  60  10   0 
GCD  55  38  59  35 /  80  70  10   0 
DLS  65  43  66  43 /  30  10   0   0