687
FXUS66 KPDT 050511
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1011 PM PDT Thu Jul 4 2024

Updated Aviation Discussion

.AVIATION...06z TAFs...VFR conditions expected. Skies will remain
clear with light, terrain-driven winds less than 12 kts. Evans/74

&&

PREV DISCUSSION... /issued 303 PM PDT Thu Jul 4 2024/

SHORT TERM...An anomalously strong offshore upper-level ridge
continues to build and slowly migrate eastward. Heights are
rising across the forecast area, and temperatures have warmed in
response. In general, temperatures are 5-10 degrees warmer this
afternoon relative to yesterday. Expect continued warming of
similar magnitude tomorrow afternoon and Saturday afternoon. Heat
highlights go into effect tomorrow afternoon as the region will
see the onset of a long-duration heat wave. Temperatures in the
90s and lower 100s will be widespread for the lower elevations,
and nighttime cooling will be modest.

While winds are generally expected to be light and diurnally
driven across the region as the ridge builds overhead, two
exceptions will be Friday afternoon and evening through the
Kittitas Valley, and again Saturday afternoon and evening in
portions of central Oregon. Confidence is medium-high (50-70%
chance) in Red Flag conditions being met, thus Fire Weather
Watches are in effect for fire weather zones WA690 (Friday) and
OR610/OR611/OR640 (Saturday). Uncertainty in Red Flag conditions
Saturday is due to model differences in the magnitude of winds
aloft, and resultant winds that mix to the surface, as a
shortwave tracks across the northern Rockies. Plunkett/86

LONG TERM...Sunday through Thursday...High pressure ridging will
be in firm control of the region through the duration of the
long-term forecast period, shifting ever so slowly across with
minimal changes to daily conditions outside of overall quantity of
heat and thereby HeatRisk. Sunday the high begins just off to our
southwest with an upper level northwesterly flow anticipated. The
center of the ridge should place itself directly over the inland
PacNW by Tuesday, and then by Thursday we should see upper level
flow shift to a southwesterly direction. Highs will slowly and
steadily increase through the middle of next week, with widespread
triple digits for our lower elevations (90-100% confidence) and
temperatures nearing 110 for portions of the Columbia Basin
(70-90% confidence). The NBM presents the best chances for these
110 temperatures on Tuesday and Wednesday with similar
probabilities each day.

Our one chance at a cool down may occur on Wednesday into Thursday
when a shortwave trough should round the high pressure ridge. This
feature isn`t expected to help produce much in the way of
significant weather, but should help "temper" our conditions back
down into the upper 90`s to low triple digits - a meager cooling
trend, but one nonetheless. HeatRisk remains moderate to high
through Wednesday, with patches of major HeatRisk on Tuesday. This
threat begins to temper by Thursday with the high category
retreating as our afternoon highs drop around 5 to 10 degrees and
overnight lows start dropping back into the 50s to low 60s. In
any case, hope everyone is prepared for the heat, as it doesn`t
look like it`s going anywhere anytime soon. Goatley/87

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  56  95  60  96 /   0   0   0   0
ALW  60  98  63  98 /   0   0   0   0
PSC  61 100  64 101 /   0   0   0   0
YKM  58 100  61 100 /   0   0   0   0
HRI  59 100  62 101 /   0   0   0   0
ELN  59  99  64  99 /   0   0   0   0
RDM  51  97  56 100 /   0   0   0   0
LGD  53  92  57  93 /   0   0   0   0
GCD  52  95  55  97 /   0   0   0   0
DLS  64 104  66 104 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning from noon Friday to 10 PM PDT Thursday
     for ORZ041-044-507-508-510.

     Heat Advisory from noon Monday to 10 PM PDT Thursday for ORZ050.

     Heat Advisory from noon Friday to 10 PM PDT Thursday for ORZ505-
     511.

     Fire Weather Watch from Saturday afternoon through Saturday
     evening for ORZ610-611-640.

WA...Excessive Heat Warning from noon Friday to 10 PM PDT Thursday
     for WAZ024-026>029-521.

     Heat Advisory from noon Friday to 10 PM PDT Thursday for WAZ523.

     Fire Weather Watch from Friday afternoon through Friday evening
     for WAZ690.

&&

$$

SHORT TERM...86
LONG TERM....87
AVIATION...74