111
FXUS66 KPDT 022343
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
450 PM PDT Tue Jul 2 2024

Updated Aviation Discussion

.SHORT TERM...Tonight through Thursday...Forecast area continues to
be under a dry northwest flow with a ridge of high pressure off the
coast and an upper level trough over the central USA. Some locally
breezy conditions (15-25 mph) will occur along portions of the east
slopes of the Cascades through the evening before decreasing
overnight. Overall pattern and conditions remain fairly constant
through Wednesday indicating persistent conditions for temperatures
and winds.

Main changes begin to take place on Thursday as the ridge of high
pressure over the eastern Pacific begins pushing into the Pacific
Northwest. This will be the beginning of a long hot dry period that
will persist into next week. High temperatures will climb into the
lower to mid 90s across the lower elevations with pleasant 80s in
the mountains. Skies will be generally clear through the day
providing easy viewing of evening firework displays. Winds will also
be light and generally under 10 mph. Conditions will be dry with
afternoon and evening relative humidities down to 10-20 percent with
fine grass fuels being extremely dry. All said, be wise in the use
of fireworks to avoid sparking fires in the "Land of the Free and
the Home of the Brave"!

.LONG TERM...Friday through Tuesday...No changes in messaging.
Forecast confidence is high (>90%) that we will see the hottest
temperatures of the summer so far as strong, persistent ridging
moves over the PacNW during the day Friday and sticks around for the
foreseeable future. The only thing ensembles really waver on is the
exact positioning of the ridge axis, and the extent to which a
shortwave on Friday riding the ridge to our northeast modulates the
high pressure position at all. This would only serve to delay the
inevitable, however, as guidance exhibits a strong signal on the
region being enveloped by high pressure by Saturday at the latest,
and likely (70-80%) lasting through most of next week.

We have issued an Excessive Heat Watch for most of our non-mountain
zones starting this Friday and lasting through the middle of next
week. NBM probabilistic shows high probabilities (generally 60-80%)
in highs eclipsing the century mark starting on Saturday for the
majority of our population centers. We`ll have to keep an eye on
where this ridge of high pressure ultimately centers itself early
next week, as the NBM may be a bit gun-shy on temps should the high
fall directly overhead as the deterministic GFS and ECMWF currently
suggest.

Otherwise, fire weather concerns will be low, as hot temperatures
will cause RHs to sink well into the teens, but winds are expected
to be weak, outside of the usual cross-Cascade gradient that will
only be exacerbated under this heat wave. Still, the forecast looks
to be very stagnant: hot, dry, and clear. Stay hydrated! Evans/74


.AVIATION...00z TAFs...Clear skies will continue through Wednesday
afternoon. WNW winds 10-20kt gusting to 25-30kt this evening will
diminish overnight, and winds on Wednesday will be primarily light
and terrain driven with the exception of breezy winds at DLS.
Wister/85


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  55  83  55  90 /   0   0   0   0
ALW  57  86  58  93 /   0   0   0   0
PSC  59  89  59  94 /   0   0   0   0
YKM  55  88  56  92 /   0   0   0   0
HRI  58  88  57  95 /   0   0   0   0
ELN  55  83  55  90 /   0   0   0   0
RDM  46  84  49  92 /   0   0   0   0
LGD  50  79  51  87 /   0   0   0   0
GCD  48  83  50  90 /   0   0   0   0
DLS  56  88  59  97 /   0   0   0   0

&&

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

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

&&

$$

SHORT TERM...91
LONG TERM....74
AVIATION...85