208 
FXUS66 KPDT 161609
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
909 AM PDT Sun Oct 16 2022

.MORNING UPDATE... The forecast remains on track with very little 
changes needed this morning; minor updates were made based off the 
latest guidance. A robust area of high pressure continues to 
dominate the Pacific Northwest allowing for dry and abnormally warm 
conditions to persist into the middle of the week. Today, daytime 
high temperatures likely rise in to the 70s for a large portion of 
the region with near 80 possible for spots like the John Day Basin, 
Central Oregon, and locations near the base of the Blue Mtn 
foothills. Overnight low temperatures remain largely a persistence 
forecast, as little change in 850mb temperatures day to day combined 
with lighter winds, low dewpoints, clear skies, and thus 
efficient radiative cooling allows some of the higher mountain 
valley areas in central Oregon, eastern Mountains, and the 
Cascades to decouple and drop near or below freezing. It's still 
likely we’ll see a pattern change to more active fall-like 
conditions this coming weekend. Schuldt/99

&&

.PREV DISCUSSION... /issued 302 AM PDT Sun Oct 16 2022/ 

SHORT TERM...Today through Tuesday night...Water vapor 
imagery reveals an upper-level ridge axis over the Pacific 
Northwest, extending north through British Columbia and into the 
Yukon. Over our forecast area, seeing rapidly drying mid levels on 
the aforementioned water vapor imagery. Forecast soundings 
advertise precipitable water (PWAT) in the 0.3-0.5" range, drying 
through the morning to generally 0.4" or less across our entire 
forecast area. HREF ensemble mean PWATs corroborate the drying 
trend. Furthermore, nighttime microphysics imagery reveals mostly 
clear skies, and latest surface observations show mostly calm or 
very light winds for valley locations (certainly lighter than 
Saturday morning). This will lead to another chilly morning for 
high valley locations with lows in the lower 20s to lower 30s. 
Elsewhere, lows in the mid 30s to mid 40s are expected.

Yesterday's day shift introduced a Freeze Warning for the Grande 
Ronde Valley, valid 4am to 9am this morning. While confidence on
the midnight shift this morning is not quite as high in zone-
wide freezing to sub-freezing temperatures, thinking that there is
at least a 50-75% chance based on current conditions that all 
population centers in the zone reach or fall slightly below 
freezing, certainly enough to justify keeping the Freeze Warning. 
Moreover, with less wind aloft, seeing a much more uniform 
decoupling of the boundary layer and thus more uniform 
temperatures across the valley at the surface this morning.

Elsewhere, ridge top winds continue to gust 15-20 mph with
isolated gusts of up to 30 mph at particularly windy locations. 
This is expected to continue through the morning before diurnal 
winds kick in later today. Since the ridge axis is directly 
overhead, and the cross-Cascade thermal gradient will not be as 
strong today, sustained winds will be lighter than yesterday's 
offshore winds. Should see pleasant daytime highs in the 70s, with 
clear skies and dry conditions. Some haze and smoke will be 
present near active fires, and some frost is forecast this morning
for valleys in central and northeast Oregon.

Heading into Monday, a weakening trough offshore will be blocked 
from penetrating inland by the upper-level ridge, whose axis is 
anticipated to shift east over the northern Rockies, so the
forecast does not change much for Monday and Tuesday with cool 
mornings followed by pleasant afternoon temperatures and generally
light winds. Colder locations in central Oregon and the Grande 
Ronde Valley may continue to see freezing or near-freezing 
temperatures, though confidence is not high in zone-wide freezing 
temperatures to issue any freeze highlights at this time. 
Plunkett/86

LONG TERM...Wednesday through Sunday...High pressure will 
continue to influence the regions weather with above normal 
temperatures and dry conditions into Thursday. The high pressure 
begins to weaken and drift away from the area and by Friday the 
upper level pattern begins to shift into a nw direction. This may 
allow for a series of disturbances to move into the pacnw 
beginning on Friday. A moderate weather system is forecast to 
track across the two state area Friday night and into Saturday 
morning and some showers are expected across WA/OR. In addition 
pressure gradients tighten and breezy to windy conditions are 
possible. 

As the weather system pushes east...drier conditions can be 
expected. However another weather system over epac is forecast to 
move into our area late Sunday and lower snow levels. Despite the 
EOF variances indicating some uncertainty the models were aligning 
better with these next systems increasing the likelihood of 
showers and cooler temperatures anticipated for the weekend. 97

&&

AVIATION...vfr conditions will persist at all taf sites for the 
next 24 hours. However lcl mvfr conditions may be approached at taf 
site kpsc due to a lowering of vsby between 12z and 15 z. The winds 
are expected to remain light and variable. 97

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  77  40  74  41 /   0   0   0   0 
ALW  76  43  75  43 /   0   0   0   0 
PSC  75  43  73  42 /   0   0   0   0 
YKM  77  40  76  42 /   0   0   0   0 
HRI  76  41  75  42 /   0   0   0   0 
ELN  75  38  77  40 /   0   0   0   0 
RDM  79  31  76  32 /   0   0   0   0 
LGD  75  35  77  37 /   0   0   0   0 
GCD  80  41  81  39 /   0   0   0   0 
DLS  80  45  80  44 /   0   0   0   0 

&&

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

$$

UPDATE...99
SHORT TERM...86
LONG TERM....97
AVIATION...97