538
FXUS66 KPDT 071702
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1002 AM PDT Sat Jun 7 2025

Updated Aviation Discussion

.AVIATION...18z TAFs...VFR conditions will prevail over the next 24
hours. Expect mostly clear skies and light northerly winds less than
12 kts. Winds will become terrain-driven overnight. Evans/74

&&

PREV DISCUSSION... /issued 212 PM PDT Fri Jun 6 2025/

SHORT TERM...Today through Sunday night...

Key Messages:

1. Warming temperatures through the weekend.
   *Heat Advisories Issued*

2. Breezy afternoon winds today.

Current radar and visible satellite imagery showing dry conditions
as some high level clouds stream in from the northwest. This is in
response to northwest flow aloft being over the region as an
upper level ridge begins to push onshore this evening and move
overhead through the weekend. Temperatures will continue to trend
upward as highs approach triple digits on Sunday. Clear skies
tonight will allow for some overnight relief as the northwest flow
aloft slowly gets cut off to allow Saturday morning low
temperatures to drop into the 50s and low-60s. The flow becomes
more zonal, or from the west, Saturday and Sunday to keep lows in
the mid-to upper 60s as highs break into the mid-to upper 90s
across the Columbia Basin. These temperatures and lack of
overnight relief have warranted the issuance of Heat Advisories
across the Lower Columbia Basin, Gorge, Blue Mountain foothills,
and the Yakima/Kittitas Valleys from 11 AM through 9 PM Sunday.

A weak shortwave riding down the front side of the incoming ridge
has brought breezy conditions across the northern Blue Mountain
foothills and the Yakima/Kittitas Valleys today. Sustained west-
northwest winds of 15 to 25 mph and gusts of 25 to 35 mph will be
possible in these areas, peaking between 5 PM and 8 PM this
evening. Confidence in these wind values is high (70-90%) as the
HREF and NBM suggest a 75-95% chance of gusts reaching 30 mph or
greater. 75


LONG TERM...Monday through Friday...

Key Messages:

1. Hot Temperatures through Tuesday.
   *Excessive Heat Watches and Heat Advisories Issued*

2. Dry lightning potential Tuesday.

3. Breezy winds Tuesday through Thursday.

The extended period is characterized by an initial upper level
ridge of high pressure, followed by a cooling upper level trough
later in the week as an upper low lingers along the British
Columbia coast. The primarily concern will be related to heat
Monday and Tuesday, with Monday expected to be the warmest day as
highs peak in the 100-105 range across the Lower Columbia Basin,
Gorge, Northern Blue Mountain foothills, and the Yakima/Kittitas
Valleys. Overnight relief will be lacking into Tuesday as morning
lows will only drop into the mid-60s to low 70s across the
aforementioned areas. Confidence in Monday`s high temperatures is
high (75-95%) as the NBM suggests a 75-95% chance of 100 degree
temperatures or above on Monday. Confidence in reaching 100
degrees across the Columbia Basin, Blue Mountain foothills, and
the Yakima/Kittitas Valleys drops to a 30-50% chance on Tuesday as
an approaching shortwave from our southwest brings in additional
cloud cover. These hot conditions, coupled with little overnight
relief, has warranted the issuance of an Excessive Heat Watch
across the Columbia River Gorge, Southern Blue Mountain foothills,
and the Yakima/Kittitas Valleys Monday morning through Tuesday
night. Heat Advisories are also active Monday and Tuesday over the
Lower Columbia Basin and the northern Blue Mountain foothills.

The incoming upper level trough on Tuesday will breakdown the
backside of the departing ridge to provide a chance (20-25%) of
thunderstorms across Central and Eastern Oregon through the
afternoon and evening. The NBM advertises mean surface CAPE of
200-300 J/kg through Deschutes, Crook, Grant, Union, and Wallowa
counties. As a result of the strong upper level ridge of high
pressure over the weekend, lower levels of the atmosphere will be
rather dry. This will lead to any developing thunderstorms lacking
any substantial moisture as only a 5-10% chance of a wetting rain
(0.10" or greater) and a 20-40% chance of measurable rainfall
(0.01" or greater) is suggested by the NBM. A 10-15% chance of
thunderstorms exists for Wallowa county on Wednesday, but should
only be confined along the extreme east of the county/state
border.

The incoming shortwave will also bring with it the potential for
elevated winds Tuesday through Thursday as a fairly substantial
pressure gradient develops along the Cascades. The gradient looks
to be strongest Tuesday night into Wednesday as the GFS suggests a
12-13 mb difference between Portland and Spokane. This value does
reach the normal advisory threshold of 12 mb, which also aligns
with the NBM that advertises a 45-65% chance of advisory level
wind gusts (45 mph or greater). so at this time, it does look
probable (50-60%) that a Wind Advisory may be necessary across the
Kittitas Valley on Wednesday. 75

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  91  61  96  63 /   0   0   0   0
ALW  90  64  94  67 /   0   0   0   0
PSC  94  59  99  61 /   0   0   0   0
YKM  93  64  97  66 /   0   0   0   0
HRI  95  60  99  62 /   0   0   0   0
ELN  93  60  97  64 /   0   0   0   0
RDM  92  53  94  54 /   0   0   0   0
LGD  86  57  90  58 /   0   0   0   0
GCD  90  56  93  57 /   0   0   0   0
DLS  93  65  99  67 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory from 11 AM to 9 PM PDT Sunday for ORZ041-044.

     Extreme Heat Watch from Sunday evening through Tuesday evening
     for ORZ041-044-508.

     Heat Advisory from 11 AM Sunday to 9 PM PDT Tuesday for ORZ507.

WA...Heat Advisory from 11 AM to 9 PM PDT Sunday for WAZ024-026-027.

     Extreme Heat Watch from Sunday evening through Tuesday evening
     for WAZ024-026-027.

     Heat Advisory from 11 AM Sunday to 9 PM PDT Tuesday for WAZ028-
     029.

&&

$$

SHORT TERM...75
LONG TERM....75
AVIATION...74