773 
FXUS66 KPDT 231716
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
916 AM PST Sat Nov 23 2019

.UPDATE...
The morning forecast update has been issued. Fog and low clouds
linger, but for the most part, visibilities are increasing and
temperatures are slowly rising to at or above freezing. Therefore,
the freezing fog advisory is being cancelled. There could still be
some areas of dense fog, but think conditions will continue to
improve and will handle with a special weather statement.  

Otherwise, made some adjustments to cloud cover and temps.  

&&

.PREV DISCUSSION... /issued 230 AM PST Sat Nov 23 2019/ 

SHORT TERM...Today through Monday...The freezing fog advisories
in effect for the Lower Columbia Basin and the WA Blue Mtn
Foothills will be expanded to include the Oregon side of the
Foothills this morning. The ridge is flattening as a westerly flow
aloft increases, and high clouds have spread over the area. This
will help provide mixing for improving conditions this afternoon,
but the lack of sun for most of the day will keep areas blanketed
by the stratus clouds cold with temperatures in the mid-30s to
mid-40s. The remainder of the forecast area will observe highs in
the mid-40s to mid-50s. Overall, a quiet weather day with light
winds (locally breezy in the Grande Ronde Valley).

More active weather is on the way beginning tonight through the
middle of the week. As the westerly flow increases, a Pacific
front will make its way across WA/OR tonight and Sunday. Rain and
high elevation snow will develop along the WA Cascades tonight. 
The front will slide southward on Sunday with increasing chances 
of precipitation over the OR Cascades as well as our eastern zones 
on Sunday. Due to rain shadowing off the Cascades, the Columbia 
Basin down to the Columbia Deschutes Plateau will observe little 
to no precipitation with this system. Precipitation will taper off
or end Sunday evening. Liquid precipitation amounts will vary from
a trace to 0.25 inch with the heaviest amounts along the east 
slopes of the WA Cascades and the northern Blue Mtns. Snow levels
will lower Sunday and will range from 3000 feet in south central
WA sloping upwards to 5000-6000 feet over central and northeast
OR. Winds along exposed ridgetops, particularly in south central 
WA, will be strong Sunday. Breezy winds can be expected elsewhere.

There will be a break in precipitation Sunday night before the
next system arrives on Monday. The cold front will bring breezy winds
as well as snow down to around 2500 feet. Even elevations between
2000-2500 feet may observe a rain/snow mix. Snow accumulations on
Monday will be around 1-3 inches for most of the region, but 
amounts around 3-6 inches are forecast along the higher 
elevations of the OR Cascades, including Mt. Bachelor. It will be
a chilly Monday with highs in the 30s in the mountains and 40s in
the lower elevations. Wister

LONG TERM...Monday night through Friday. A disturbance over the 
pacnw will remain stationary over the pacnw through the period. Snow 
levels will hover around 3k feet before lowering by midweek to 
around 1k feet or lower. Rain and snow showers could become all snow 
showers by Wednesday as an upper level low drops into the two state 
area and brings even colder temps and breezy winds. Snow 
accumulations are possible especially over the area mountains during 
the extended while afternoon temps struggle to reach freezing mark 
Wednesday and Thursday. The upper level low pressure drifts away but 
our area will remain in the snow showers into Friday.

AVIATION...Areas of mvfr and local ifr can be expected at taf sites 
kalw and kpsc along with kpdt through 18z. The fog may be slow to 
burn off and areas of mvfr may persist after 18z. Meanwhile the 
other taf sites should remain mostly vfr except for taf site kykm 
that may experience lcl mvfr between 12z and 18z. 

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  36  53  35  43 /   0  10  20  40 
ALW  34  52  34  44 /   0  30  30  50 
PSC  32  56  35  47 /   0   0  10  30 
YKM  32  53  27  47 /  10  10  10  20 
HRI  35  56  34  48 /   0   0  10  30 
ELN  34  49  28  43 /  30  20  20  20 
RDM  29  51  25  42 /   0  10  30  40 
LGD  32  47  30  40 /   0  40  30  60 
GCD  34  47  29  40 /   0  20  30  50 
DLS  36  53  36  47 /  10  20  20  20 

&&

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

$$

77/93/93