092
FXUS66 KPDT 202205
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
305 PM PDT Thu Jun 20 2024

.SHORT TERM...This afternoon through Saturday night...Day Cloud
Phase RGB imagery reveals some cumulus build-ups across the WA
Cascade crest and Blue Mtns. Any convection that develops is still
expected to remain isolated this afternoon and evening.

The weak shortwave trough overhead will exit to the east
overnight. Flow aloft will transition to a zonal pattern Friday,
followed by continued height rises across the PacNW Saturday as an
upper-level ridge amplifies over the northern Rockies. The result
will be warming temperatures tomorrow and Saturday. Afternoon RH
values will be low to very low.

HeatRisk values will increase to Moderate across much of our
population centers Friday and Saturday. Additionally, the
probability of 90+ degree afternoon high temperatures is 70-95%
for Saturday across non-mountain areas.

Late Saturday, a mid/upper-level low will track towards the PacNW,
resulting in a switch to onshore-directed surface pressure
gradients and increasing gap winds. Plunkett/86

&&

.LONG TERM...Sunday through Thursday...A upper level ridge exits
eastward Sunday as the zonal pattern moves over the region
through Monday. The ridging will continue building into the PacNW
late Monday through Wednesday. As the ridge exits to the east, a
upper level trough will then move across the PacNW off OR coast
through Thursday. Thunderstorms are possible in the eastern
mountains for late Wednesday and late Thursday, given the
orographic lifting from the cold front associated with a closed
low off British Columbia. However, chances are on the low end with
surface CAPE values below 100 J/Kg and weak instability (<15%).
Confidence is low for mountain showers at the crest of WA/OR
Cascades late Wednesday through Thursday from the dry cold front.
Seasonable temperatures will be Sunday through Monday as the zonal
pattern passes. Tuesday into late Wednesday, temperatures start
warming up again due to the transient ridge before decreasing
Thursday with the arrival of the upper trough off the coast.

Wind gusts at 25-35 mph will begin Sunday afternoon into early night
along the lower Columbia Basin, Columbia River and Kittitas Valley
(>70% chance). Probability is moderate for wind gusts exceeding to
40 mph (60-80%). Due to increased northwesterly winds and dryness,
fire weather remains to be a concern for Sunday around Columbia
Basin. Nonetheless, winds will continue to decrease late Sunday
night. Breezy conditions continue across the forecast area with wind
gusts at around 20 mph or less through Wednesday (40-50%
probability). Though, confidence increases for increased wind gusts
in these areas Thursday from the arrival of the cold front
associated with the trough. Feaster/97


&&

.AVIATION...18Z TAFS...VFR conditions are expected during this
period with light winds, aside from afternoon gusts to around
15-20 kts. Mostly clear skies with some mid to high clouds during
the next 24 hours. Feaster/97

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  54  89  57  93 /   0   0   0   0
ALW  53  92  59  96 /   0   0   0   0
PSC  59  94  61  98 /   0   0   0   0
YKM  56  92  60  95 /   0   0   0   0
HRI  56  94  61  98 /   0   0   0   0
ELN  50  91  59  92 /   0   0   0   0
RDM  51  88  54  91 /   0   0   0   0
LGD  52  85  55  92 /  20   0   0   0
GCD  49  88  55  95 /   0   0   0   0
DLS  57  95  64  92 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
&&

$$

SHORT TERM...86
LONG TERM....97
AVIATION...97