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Area Forecast Discussion (AFD)

Issued by Pendleton, OR (PDT)

FXUS66 KPDT 240523 AAA

Area Forecast Discussion
National Weather Service Pendleton OR
1030 PM PDT Sat Mar 23 2019

Updated Aviation Discussion

.UPDATE...Band of moisture/light rain continues to move from
southeast Oregon northwest into the lower Columbia Basin. The
upper low will continue to push into northern California tonight
with moisture being funneled across eastern Oregon into central 
Washington. The system may be a little slower to move out on 
Sunday. Mainly updates to pop and qpf and bumped up overnight 

There are hydro concerns about the amount of moisture that will 
continue across northeast Oregon with snow levels not lowering as
fast as originally thought. Per RFC, the higher pops and qpf were
incorporated and forecast points along the Umatilla River, Grande
Ronde River and Touchet River will see strong rises, but at this 
time should remain below flood stage. 93


.AVIATION...06Z TAFS...MVFR cigs at times overnight and through the 
morning hours at PDT/ALW/PSC as band of showers continue to spread 
northwest from Oregon into Washington. The upper low will shift east 
on Sunday with showers ending from west to east and VFR conditions. 
Winds will 10-15 kts tonight, then under 10 kts on Sunday. 93


.PREV DISCUSSION... /issued 430 PM PDT Sat Mar 23 2019/ 

SHORT TERM...Tonight through Monday night. A low pressure system
was moving across Oregon and will combine with moisture to produce
showers across the region tonight. The best chance of pcpn will
occur over our se cwa where the models were generating upwards to
a quarter inch of pcpn that could further aggravate swollen 
rivers and streams. Some snow accumulation is possible for 
elevations as low as 3500k feet tonight. Elsewhere scattered 
showers will persist especially in the mountains into Sunday while
the bulk of the pcpn will shift into the eastern mountains. Some 
drier air will work its way into the western sections tomorrow 
before pushing east Sunday night. Another disturbance will 
approach the two state area Monday with increasing clouds and 
showers expected along the wa/or cascades that will migrate into 
the remainder of the region Monday afternoon. The showers will 
move east with some drying expected Monday night. Temperatures
will remain near normal through the period.

LONG TERM...Tuesday through Sunday...An elongated upper low off the 
Pacific Northwest coast will be pushing a moist southwest flow aloft 
over the forecast area on Tuesday. A weather disturbance within the 
flow will move through the CWA Tuesday night into Wednesday. This 
will bring at least scattered showers over the forecast area, 
especially in the mountains where upslope will be the greatest. This 
will be over the Blues and Wallowa Mountains due to the southwest 
flow. There will also be scattered showers over the Cascades. Snow 
levels will be around 3000 feet to 4000 feet from north to south. 
Then the models begin to diverge from each other after this point 
and the upper low will weaken, but the Canadian and GFS keep a 
trough over the region while the ECMWF tries to build a ridge for 
Thursday. Will go with the wetter solution of the models and keep 
the forecast showery and unsettled through at least Friday. After 
that the ECMWF comes more into alignment with the GFS and ECMWF and 
all want to dry conditions out with an upper ridge trying to build 
over the region. Thus will start a drying trend on Saturday and 
continue it through Sunday. Temperatures will be slightly below 
normal with max readings in the 50s for the lower elevations. Winds 
will be breezy at times, mainly on the ridge tops, and especially on 
Tuesday through Friday. 88


PDT  39  56  37  55 /  70  50   0  20 
ALW  39  56  38  57 /  70  60  10  20 
PSC  41  59  37  57 /  50  50   0  30 
YKM  39  58  36  52 /  30  30   0  40 
HRI  42  60  37  56 /  60  50   0  30 
ELN  37  57  33  50 /  30  40  10  40 
RDM  27  56  32  51 /  30   0  10  70 
LGD  33  49  32  51 /  90  60   0  20 
GCD  32  52  35  54 /  90  30   0  40 
DLS  39  59  36  51 /  10   0   0  70