949 
FXUS66 KPDT 120515
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1015 PM PDT Mon Sep 11 2023

Updated Aviation Discussion

.EVENING UPDATE...Satellite imagery showing mid to high level 
cloud cover continuing to push east across the region this 
evening, while at the surface a marine push has resulted in breezy
winds through the Cascade gaps. The first of a series of weak
upper shortwaves with attendant frontal boundaries is the main
driver of the increased cloud cover and breezy gap winds this
evening. That said, conditions have remained dry overall, with the
dry trend continuing through tonight. Through the second half of
tomorrow, a shortwave trough will pass through the PacNW,
resulting in increased breezy winds through the Cascade gaps.
A majority of the forecast area will once again remain under dry
conditions through this system passage, however, the Washington
Cascade crest could see some light rain overnight Tuesday as the
shortwave axis clips this area. Temperatures will remain near
normal tomorrow, with mid 70s to mid 80s in the lower elevations,
and 60s to mid 70s in the mountains. Lawhorn/82

.AVIATION...06Z TAFs...VFR conditions to prevail through the
period. CIGS of sct-bkn AOA 20kft to 25kft AGL will affect all
sites. Winds will mostly be light, less than 12kts, through the
period at sites RDM/BDN/YKM/ALW/PSC. Site DLS will see winds
increase to 12-20kts with gusts 25-30kts develop tomorrow
afternoon. Site PDT will see winds increase to 12-15kts with gusts
up to 25kts possible in the afternoon tomorrow. Lawhorn/82

PREV DISCUSSION... /issued 402 PM PDT Mon Sep 11 2023/ 

.SHORT TERM...Tonight through Wednesday...Models continue to 
be in good agreement on the evolving weather pattern as an upper 
level trough has begun moving into the region. This is ushering in 
some mid and high level clouds and producing a weak marine push with 
breezy winds through the Columbia Gorge and Kittitas Valley to 
locally breezy elsewhere along the east slopes of the Cascades. 
Could cover and the advection of slightly cooler air is resulting 
in cooler high temperatures today. The trough axis will approach 
Tuesday with passage overnight. This will cause a further increase 
in westerly winds. Fortunately, min humidities will only be down to 
around 25-30% so do not see this as a Red Flag event but local 
winds of 15 to 30 mph along the east slopes of the Cascades will 
still be capable of causing control issues should fire start. Winds 
will become lighter Wednesday as we transition to a more NE-E flow. 
High temperatures Tuesday and Wednesday will be near normal which is 
upper 70s to near 80 in the Basin and low 70s in the mountains. 
Precipitation threat is low with only the Washington Cascade crest 
likely to see some light rain Tuesday night. 

.LONG TERM...Thursday through Monday...Not much change in the 
long term, which remains quiet as ensembles continue to key in on 
high pressure extending from the end of the work week through most
of the weekend. We'll see a bit of a warming trend as a result, 
with highs reaching the lower 90s throughout most of our 
population centers by the weekend. This runs about 10 to 15 
degrees above average for the time of year, but periods of dry and
warm conditions are certainly not unheard of around here for 
September. Sensible weather concerns remain limited due to high 
pressure, as winds will remain light even as RHs dip into the 
teens to lower 20s. Outside of potentially deteriorating air 
quality due to area smoke under subsidence aloft, much of the 
period looks to be quiet. 

Ensembles hint at a shortwave arriving around the tail end of the 
period, potentially bringing showers to our high mountain zones. 
This system, should guidance verify, will also reverse our warming 
trend to start off the next work week, but forecast confidence is 
low as much can change with subsequent model runs between now and 
day 7 onward. Evans/74

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  79  52  76 /   0   0   0   0 
ALW  60  81  55  78 /   0   0   0   0 
PSC  62  83  59  81 /   0   0   0   0 
YKM  54  82  51  80 /   0   0   0   0 
HRI  60  83  56  81 /   0   0   0   0 
ELN  54  76  55  76 /   0   0   0   0 
RDM  46  77  45  77 /   0   0   0   0 
LGD  53  79  50  75 /   0   0   0   0 
GCD  50  82  48  77 /   0   0   0   0 
DLS  59  80  57  82 /   0   0   0   0 

&&

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

$$

EVENING UPDATE...82
SHORT TERM...91
LONG TERM....74
AVIATION...82