459
FXUS66 KPDT 062335
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
435 PM PDT Sat Jul 6 2024

.Updated for Aviation...



.PREV DISCUSSION... /issued 235 PM PDT Sat Jul 6 2024/

SHORT TERM...Tonight through Monday...High pressure ridge is in
firm control now, with minimal changes to the forecast reasoning
from the past several days. As this feature continues to slowly
move eastwards during the period, expect temperatures to steadily
rise 1-3 degrees each day, culminating with our hottest
temperatures just beyond the short term on Tuesday. Ensembles
continue to present the heat with high confidence in widespread
triple digit temperatures with near certain confidence (90-100%),
and high confidence (70-80%) locations such as the Columbia Basin
and Columbia Gorge will see temperatures near or just around 110
by Tuesday but possibly as early as Monday. HeatRisk shows
widespread moderate to major today, with widespread major and
pockets of extreme for Sunday and Monday. The one caveat to the
forecast has been morning lows, which the NBM has been notably
warm biased for many lower elevation locations. This has been
tempered with some edits based on the biases from the last couple
of days to help alleviate that.

Fire weather concerns today are already validating as we show
several sites starting to reach red flag criteria as of this
writing. Expect winds 10-20 mph with gusts of 25 for areas of
Central Oregon and into the Southern Blue and Strawberry Mountains
with significantly low RH`s into the single digits and teens.
Sunday winds look to temper just enough that concerns should fall,
but widespread teen and single digit RH values aren`t going
anywhere anytime soon, and fuels will continue to bake under the
summer heat. Goatley/87

LONG TERM...Tuesday through Saturday...The main concerns during the
period will be continued hot and dry conditions area-wide. Heat
highlights are currently out through Thursday evening for many of
our forecast zones, and temperatures are anticipated to peak Tuesday
and Wednesday.

Ensemble NWP guidance favors a slow eastward migration of the
anomalously strong mid- to upper-level ridge that is currently
centered over NW California, culminating in a Four Corners High
setting up by the weekend. Additionally, some semblance of offshore
troughing in the Northeast Pacific and a northeastward-propagating
shortwave will result in southwesterly flow across the forecast area
Wednesday and Thursday. Elevated fire weather concerns are appearing
more likely Wednesday afternoon and evening as a surge of westerly
winds envelops the region, strongest through the Cascade gaps and
across the Columbia Plateau. The increasing winds will be in
response to eastward-directed pressure gradients as a trough passes
offshore to the northwest. Moreover, the aforementioned eastward
progression of the ridge will place the hottest surface temperatures
inland, leading to a diurnal enhancement of surface pressure
gradients that will help drive westerly winds. Additionally,
cooling temperatures up through 850 mb will aid in 20-35 kt 850 mb
winds through the gaps and across the Columbia Plateau. While no
widespread Red Flag conditions are forecast on Thursday, localized
breezy conditions and fire weather concerns are forecast to
linger, mainly through the Cascade gaps.

Some solutions are advertising a mid-level speed max amidst
southwesterly flow transiting the Blue Mountains region Wednesday
afternoon. While this would normally favor thunderstorms, moisture
at all levels appears meager in forecast soundings, so confidence in
any thunderstorm threat (dry or wet) is very low (<10% chance) at
this time.

Through the remainder of the period, ensemble mean 500 mb heights
and individual ensemble clusters are in good agreement that warm to
hot temperatures will continue, but details of the pattern remain
unclear. By Saturday, some uncertainty develops with regard to
monsoonal moisture being advected northward into the PacNW.
Confidence is quite low (<10% chance) in this solution, and ensemble
means favor near-normal PWATs. Plunkett/86

.AVIATION...
00Z TAFS...VFR conditions (100%) probability with winds mainly
less than 10 kts. The only exceptions will be at DLS, BDN and RDM
where gusty winds to around 25 kts will linger through the evening
today before decreasing to less than 10 kts. Gusty winds will
redevelop again on Sunday afternoon in the 20 to 25 kt range.

&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  60 100  62 102 /   0   0   0   0
ALW  60 103  62 105 /   0   0   0   0
PSC  63 104  65 106 /   0   0   0   0
YKM  68 102  70 105 /   0   0   0   0
HRI  62 104  64 106 /   0   0   0   0
ELN  59 102  63 105 /   0   0   0   0
RDM  54 101  56 101 /   0   0   0   0
LGD  53  95  56  99 /   0   0   0   0
GCD  54  98  57 101 /   0   0   0   0
DLS  65 108  67 108 /   0   0   0   0

&&

.PDT WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 10 PM PDT Thursday for ORZ041-044-
     505-507-508-510-511.

     Heat Advisory from noon Monday to 10 PM PDT Thursday for ORZ049-
     050-502-503.

     Red Flag Warning until 9 PM PDT this evening for ORZ610-611-640-
     642.

     Heat Advisory from noon Monday to 10 PM PDT Tuesday for ORZ509.

WA...Excessive Heat Warning until 10 PM PDT Thursday for WAZ024-
     026>029-521-523.

     Heat Advisory from noon Monday to 10 PM PDT Thursday for WAZ030.

     Heat Advisory from noon Monday to 10 PM PDT Tuesday for WAZ522.

&&

$$

SHORT TERM...87
LONG TERM....86
AVIATION...77