151
FXUS66 KPDT 140928
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
228 AM PDT Wed Aug 14 2024

.SHORT TERM...Today through Friday...Overnight satellite imagery
showing mostly clear skies over the forecast area as transitory
ridging builds in overhead. Most of Wednesday will be quiet as a
result, however our quiet weather will be short-lived as a series of
low pressure systems will impact the PacNW starting overnight
Wednesday into Thursday, keeping us in an active pattern through at
least early next week.

Not much to speak of weather-wise today, but models are in good
agreement showing a closed upper-level low arriving from the WSW
during the overnight hours heading into Thursday, bringing with it a
band of showers and thunderstorms along a warm front leading the
system. Fire Weather Watches are in effect as a result, however the
main complicating factor with this system is just how cool we`ll be
heading into Thursday, which will work toward cutting into
instability needed for storm activity. Currently looking at
overnight lows in the low 50s to even 40s for many of the zones
under a Fire Weather Watch, which isn`t too cold for convection, but
whether or not we`ll see "abundant lightning" remains to be seen.
We`ll leave the decision whether to upgrade or drop the Watch to the
day shift, but will say that as far as storm chances are concerned,
the best chances do look to be concentrated around central Oregon.

Shower and storm activity looks to spread northeastward up through
the Blues and Wallowas during the day Thursday, but forecast models
show a pretty saturated air mass with PWATs anywhere from 0.7 to 1
inches, certainly above average given the time of year. Storm
chances are certainly there, but current thinking is that wetting
rains may play enough of a factor to preclude issuing fire weather
headlines for our eastern mountain zones. That being said, it is mid-
August, and fuels are at their most vulnerable, but the forecast
does look to be wet overall for the eastern mountains Thursday.

A more robust low will begin to take shape on Friday, but with
prolonged SW flow and moisture over the forecast area, cloud cover
will work to severely inhibit instability, thus CAPE is expected to
be very limited. What looked to be another day of storms now looks
to be that of meager shower activity over the eastern mountains.
High temps are expected to remain around seasonal averages. Evans/74

.LONG TERM...Saturday through Wednesday...Ensemble models continue
to show good agreement that the long term weather pattern will
consist of an upper level closed low pressure off the coast of the
Pacific Northwest but in various locations over time. This will
place the forecast area under a south to southwest flow throughout
the long term period. The initial deepening of this low occurs late
Friday into Saturday which coincides with the best period of
instability across the forecast. area. This will lead to showers and
thunderstorms on Saturday. On Sunday the center of the low lifts a
little further north allowing a dry slot to cover most of the
forecast area while the better instability also shifts north and
east of the forecast area. Monday through Wednesday the closed low
will be located off the coast of Vancouver Island and a continuation
of a dry slot across the forecast area being on the southeast side
of the low. This keeps the better instability and moisture north and
east of the forecast area with precipitation chances at 10% of less
for the forecast area. Throughout it all, temperatures look to
remain near seasonal norms with highs generally in the 80s in the
lower elevations and 70s in the mountains.

&&

.AVIATION...12Z TAFS...VFR conditions are expected through the 24
hour forecast period but do expect the development of some
showers and possible thunderstorms in central Oregon after 00Z and
overnight that could impact RDM and BDN. Otherwise, generally
clear skies and winds of 5 to 15 kts expected. BDN/RDM and YKM may
still be locally impacted from smoke/haze from nearby wildfires.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  82  53  82  54 /   0   0  20  20
ALW  86  57  85  59 /   0   0  20  30
PSC  87  60  88  62 /   0   0  10  10
YKM  86  55  87  54 /   0   0  20  20
HRI  87  59  86  59 /   0   0  10  10
ELN  88  57  86  56 /   0   0  10  10
RDM  82  51  77  47 /   0  20  30  30
LGD  84  52  80  50 /   0   0  50  50
GCD  86  54  80  50 /   0  30  60  40
DLS  85  61  81  59 /   0   0  10  10

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from this evening through Thursday morning
     for ORZ611-640-642.

WA...None.
&&

$$

SHORT TERM...74
LONG TERM....91
AVIATION...91