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000 
FXUS66 KPDT 212040
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1240 PM PST Thu Nov 21 2019

.SHORT TERM...Tonight through Sunday night...The upper level ridge 
will remain over the region through Saturday but begin flattening as 
a shortwave passes through Canada overnight and Friday. There will 
be some fog and stratus development mainly around the Columbia Basin 
overnight, some of which will persist through Friday and into 
Saturday. The ridge will eventually flatten enough that by late 
Saturday night and Sunday a cold front will sweep across the region 
under a northwest flow. This will favor the Cascades and Blue 
mountains for precipitation but not so much along the east slopes of 
the Cascades or Columbia Basin. Snow levels will lower late Sunday 
and overnight getting down to 2000 to 3000 feet. As mentioned, the 
northwest flow will favor the Cascades and Blue Mountains with 
precipitation and with lowering snow levels there will be some snow 
accumulations to deal with Sunday night for travelers over the
mountains. 

.LONG TERM...Monday through Thanksgiving...Initial shortwave/cold 
front will have shifted south and east of the CWA by Monday, but 
expect mountain unsloped snow showers to continue through Monday 
night as the region falls under moist northwest flow aloft. Locally 
breezy winds behind the front on Monday will diminish Monday night. 
A couple of weak waves passing through the flow could help to 
enhance precip, but only expect a slight chance in the basin. Snow 
levels will start off around 2-3kft. More uncertainty exists with 
the second stronger system as model solutions differ. Potent trough 
expected to dig south along the BC coast, moving into the PacNW on 
Tuesday. Upper low/long wave trough then expected to develop 
somewhere over the western US. Initial front expected to pass 
through Tue/Tue night and bring a chance of precip. Snow levels 
start off low (1500-2500ft) with cold air in place in wake of 
initial system. Models differ quite a bit towards Wednesday in 
placement and strength of upper low. GFS has been more consistent 
and more in line with the ensembles and has been dropping the low 
further south into NorCal. That would mean heavier precip for 
southern and far eastern Oregon. If surface and upper low track 
further north, then expect better threat of impactful precip amounts 
over most of our area. This could bring moderate to heavy snow for 
the mountains with the potential of snow for lower elevations, 
possibly down to around 500-1000ft. Trended towards drier GFS 
solution but still bring a decent shot of impactful snow for the 
central and northeast mountains with a chance of snow elsewhere. The 
brunt of the system should push east by Thanksgiving with drier 
conditions expected ahead of another potential potent system towards 
the weekend. Either way, temps expected to continue their downward 
trend as cold Canadian air filters into the Inland Northwest. Highs 
Monday in the mid 30s to mid 40s, and only reaching he mid 20s to 
mid 30s on Thanksgiving.


&&

.AVIATION...00Z TAFs...Lingering strato-cu over central/northeast 
Oregon will dissipate this afternoon. Otherwise expect VFR 
conditions through this evening with a few passing high clouds and 
light winds. Late tonight into tomorrow morning expect haze and 
possible fog to develop, especially near ALW and PSC, which could 
lead to MVFR or lower conditions.


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  27  44  30  51 /   0   0   0   0 
ALW  28  44  32  49 /   0   0   0   0 
PSC  26  43  29  46 /   0   0   0   0 
YKM  23  46  27  47 /   0   0   0   0 
HRI  26  44  28  48 /   0   0   0   0 
ELN  22  47  29  47 /   0   0   0   0 
RDM  19  53  24  56 /   0   0   0   0 
LGD  26  48  29  49 /   0   0   0   0 
GCD  27  50  29  53 /   0   0   0   0 
DLS  29  48  32  49 /   0   0   0   0 

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.

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