000
FXUS66 KPDT 041534
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
834 AM PDT Wed Aug 4 2021

.MORNING UPDATE...
Morning satellite imagery depicts a thick band of high level smoke
emanating from southern OR and northern CA where large fires
continue to burn. Otherwise, a few passing mid level clouds are
present across far northeast OR and southeast WA. For the
remainder of the day, with upper ridging extending across eastern
OR and WA, expect southerly flow to persist. With modest remnant
moisture and adequate heating, at least isolated thunderstorm
potential will linger mainly over the eastern mountains of OR and
southeast WA. This is noted in recent HREF runs with meager
instability and most convective-allowing members depicting a few
showers or storms developing from southeast through east central
OR late this afternoon into the evening. Unlike yesterday, the
potential for severe thunderstorms appears limited somewhat due to
capping concerns and less impressive instability. This does not
mean storms wont be accompanied by gusty winds and lightning,
however. Aside from thunderstorm chances, another hot day is
expected, though this should be the final day of upper 90s to low
100s in this streak as cooler air is poised to invade the region
beginning tomorrow.

As for the forecast, the only changes made this morning were to
winds, hourly temperatures and humidities/dewpoints to reflect
recent trends. The rest of the forecast looks to be on track.
79/Austin

&&

.AVIATION...12Z TAFs...
Once again, VFR conditions will be expected, for the most part.
There will be some areas of reduced VSBYS to MVFR in HZ or smoke
mainly this morning or afternoon, with the most likely areas being
PSC, RDM and BDN.

Otherwise, expect gusty winds at DLS to around 20 kts and BDN and
RDM in the 15 to 20 kt range.

There is a chance of some afternoon/evening TSRA again mainly
over the eastern Oregon mountains. However, coverage should be
less than on Tuesday and any TSRA should remain east of the TAF
sites.

&&

.PREV DISCUSSION... /issued 434 AM PDT Wed Aug 4 2021/

SHORT TERM...Today through Friday...Warm temperatures continue to
occur today as the ridge remains the primary influence for the
region. Upper 90`s to low 100`s will once again be possible across
the Columbia Basin, with a low-end risk of some thunderstorms
across the Blues and Wallowas. Weak wind flow should also allow
for one final full day of haze across most of the forecast area as
well.

Attention turns to Thursday as an upper low off the coast moves
inland across the CA/OR border and then up towards ID. Showers
are expected to be possible across much of Central OR up into
Southeast WA, with a slight chance at thunderstorms that could
possibly become strong enough to be severe. The risk is modest at
best giving way to a marginal threat for winds and possibly some
hail. With this low, temperatures should also drop around 5-10
degrees on average for the day as cloud cover and cooler air begin
to move in. Models have been the most inconsistent with this
portion of the forecast period, with some models such as the ECMWF
drier than others, while others still expecting little
thunderstorm activity let along severe potential.

Friday should then be much cooler still as we once again see
another 5-10 degree temperature difference with NW`ly flow. Some
lingering showers may be possible across the Wallowas Friday
morning, but should move out through the day. Another deep upper
low NW of the region will move inland across Canada, and the
trough associated with it will bring widespread precipitation for
the coastal areas of both states. This should end right at the
Cascades, though some activity could spill over before falling
apart. Goatley/87

LONG TERM...Saturday through Wednesday. Much cooler temperatures
through the weekend and early next week with westerly flow through
the weekend with a large area of low pressure over southwest Canada.
Models are still showing some differences in the pattern with
deterministic EC still the outlier in bringing a strong closed low
down over Washington and Oregon Sunday through Wednesday, while the
ensembles and GFS have more of an open trough over the Pacific
Northwest through Tuesday and then drop a low down over Idaho by
Wednesday. Have gone with the ensembles and kept forecast dry and
there will be some locally windy periods through the weekend. 93

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  99  65  92  60 /   0  10  20  30
ALW 100  68  94  64 /   0  10  30  30
PSC 100  71  97  68 /   0  10  20  20
YKM  99  68  96  63 /   0   0  10  10
HRI 102  68  96  65 /   0  10  20  20
ELN  97  66  91  64 /   0   0  10  10
RDM  97  58  86  52 /   0  10  20  10
LGD  98  64  90  57 /  10  20  40  50
GCD 101  64  93  56 /  20  20  40  40
DLS 102  70  89  67 /   0  10  10  20

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory until 11 PM PDT this evening for ORZ041-044-507-
     508.

     Fire Weather Watch from Thursday morning through Thursday
     evening for ORZ642>645.

WA...Heat Advisory until 11 PM PDT this evening for WAZ024-026>029-
     521.

     Fire Weather Watch from Thursday morning through Thursday
     evening for WAZ643-645.

&&

$$

SHORT TERM...79
LONG TERM....93
AVIATION...77

NWS PDT Office Area Forecast Discussion