Heat Advisory 8, NWS Pendleton, OR

Area Forecast Discussion
National Weather Service Pendleton OR
1013 AM PDT Tue Aug 10 2021

Updated aviation discussion

.UPDATE...Minor tweaks to our temperatures and subsequently RH's
and dewpoints were the primary focus, looking specifically at
southern areas of our forecast zone where stronger cold pools have
allowed very cool morning temperatures. Reduced tomorrow's lows
by a couple to a few degrees while also increasing RH's.
Otherwise did not make significant touches to the weather as it is
becoming likely we will begin to see hazy skies as smoke fills in
aloft, as apparent from our own windows here at the office.
Goatley/87

.AVIATION...18Z TAFS. Cirrus moving across the region today with
FEW-SCT250. Mostly clear tonight SKC-FEW250. Winds less than 10kt.

&&

.PREV DISCUSSION... /issued 428 AM PDT Tue Aug 10 2021/

SHORT TERM...TODAY THROUGH THURSDAY...The departing upper level
trough continues to loosen its influence across the PacNW as a
strong upper level ridge pushes onshore from the northern Pacific
later today. This will lead to significant warming as the ridge
centers over our area through the remainder of the week. High
temperatures will be steadily increasing each day, with a 5-8
degree increase today then another 5-10 degree increase Wednesday
as highs hover between 100 and 107 across the Eastern Gorge, Lower
Columbia Basin, and the east slopes of the Cascades. Temperatures
will continue this trend into Thursday, but only increasing a
couple degrees between 103 and 110. Little overnight relief is
expected with morning lows staying in the upper 60s to low 70s
starting Thursday. Thus, the Excessive Heat Watch is still
warranted from Wednesday through Saturday.

The departing trough, incoming ridge, and northwest flow aloft
will lead to some breezy conditions through the Kittitas Valley
through Wednesday, which should peak between 17 and 25 mph during
the evening and early morning hours. Otherwise, winds should be
relatively light and terrain driven as the ridge infiltrates into
our area. Widespread haze is also expected through much of the
week as low winds and sinking air associated with the ridge will
keep smoke from nearby wildfires in the Basin. 75

LONG TERM...FRIDAY THROUGH TUESDAY...Main concerns for the
extended period will be continued hot weather through Saturday
along with a chance of thunderstorms then breezy to windy
conditions Sunday into Monday. Strong upper level ridge will be
over the region Friday and Saturday. 850mb temperatures are
25-30C. This will give highs of 100-110 with 90s for the mountains.
The excessive heat watch will remain in effect through Sat evening.
As the upper level ridge axis moves slowly to the east a southerly
flow aloft will overspread much of the forecast area. Moisture and
instability will increase and there will be a chance of thunderstorms
over central Oregon Fri and Sat afternoon and evening. The remainder
of the region will be partly cloudy and hazy. By Sunday an upper
level trough will move into the Pacific northwest. This will bring
a cooling trend with highs back into the 80s and 90s along with a
few showers over the mountains. Westerly winds will increase with
breezy to windy conditions likely. A larger upper level trough
will then set up over the northwest for Mon and Tue with cooler
temperatures. Expect partly to mostly cloudy and breezy
conditions. 94

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  93  62 100  66 /   0   0   0   0
ALW  94  67 103  71 /   0   0   0   0
PSC  96  65 103  70 /   0   0   0   0
YKM  95  64 104  71 /   0   0   0   0
HRI  97  63 105  68 /   0   0   0   0
ELN  94  63 104  67 /   0   0   0   0
RDM  95  57  99  60 /   0   0   0   0
LGD  91  60  97  62 /   0   0   0   0
GCD  93  59  99  64 /   0   0   0   0
DLS  97  68 105  73 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Watch from Wednesday afternoon through Saturday
     evening for ORZ041-044-049-505-507-508-510-511.

WA...Excessive Heat Watch from Wednesday afternoon through Saturday
     evening for WAZ024-026>029-521.

&&

SHORT TERM...87
LONG TERM....94
AVIATION...94