844
FXUS66 KPDT 071743
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
1043 AM PDT Sun Jul 7 2024

Updated Aviation Discussion

.AVIATION...18Z TAFs...VFR conditions and SKC over the next 24
hours. Breezy winds for DLS/BDN/RDM this afternoon, with gusts
15-23 knots, but otherwise winds 10 knots or less all other sites.
Goatley/87


&&

.PREV DISCUSSION... /issued 302 AM PDT Sun Jul 7 2024/

SHORT TERM...Today through Tuesday...Little change in the
forecast tonight as upper level ridging will dominate the synoptic
pattern through the next several days. Water vapor imagery tonight
shows the ridge slowly moving east, with the ridge axis inching
ever closer onshore. As the ridge continues to move east, expect
afternoon temperatures to increase another 1 to 3 degrees and
morning lows to increase another 2 to 4 degrees through Tuesday.
Confidence remains very high(90-100%) that widespread triple digit
degree temperatures will develop by tomorrow in the lower
elevations, with NBM probabilities showing a 60-75% chance that
areas of the Columbia Basin, eastern Gorge, and the John Day Basin
will reach or exceed 110 degrees Tuesday. As for HeatRisk values,
today will see a mix of moderate to major, with major HeatRisk
increasing areawide Monday and Tuesday and localized extreme
HeatRisk developing Tuesday. Otherwise, the only other weather
phenomena to note are increasing mid to upper level cloud cover
Tuesday. Ensemble guidance and their deterministic counterparts
indicate a weak vort and speed max coming up southwest flow aloft at
500mb, resulting in increased cloud cover at this layer. While the
southwest flow aloft would bring concerns of thunderstorms, little
to no moisture support is noted at all levels, resulting in very
low confidence(< 10%) in any dry or wet thunderstorm development.
Lawhorn/82

LONG TERM...Tuesday through Saturday...

Bottom Line Up Front

1. Breezy conditions return Wednesday.

2. Fire weather concerns Wednesday.

3. Continued dry and warm conditions.

Models remain in firm agreement with the upper level high pressure
system slowly migrating eastward. By Wednesday an upper level off
shore weak trough will set up allowing for a slight ridge breakdown
and a shift in the upper level winds. Looking at the pressure
gradient tool, there is 9 to 10 mb difference between PDX and GEG
which leads to the conclusion that Gap winds will set up. Looking at
the raw ensembles, between 60 to 70% show that winds will be between
15 to 20 mph through the Gorge, Kittitas Valley as well as along the
lower Columbia Basin. With the warm temperatures and dry air
residing over the region, relative humidities have dropped into the
critical range with 90-100% of the raw ensembles showing relative
humidities to be below 15%. This coupled with the slight increase in
winds through the Gaps, fire weather concerns are elevated Wednesday
between 11 AM and 8 PM with high confidence of 70-80%.

Models show southwest flow to continue over the region even with the
breakdown of the upper level ridge. The incoming upper level trough
will bring with it slightly "cooler" conditions. EFI shows the
region to remain well above the climatological normal with
temperatures still averaging 10 to 15 degrees above normal with
above normal overnight temperatures. Wednesday will be the hottest
day of the long term with 73% of the raw ensembles showing the
Pendleton area to be in the upper 90s to near 104 degrees, 81%
showing the Basin to be between 105 and 110 degrees, 69% showing the
Gorge in the upper 90s to near 100 degrees and 64% having central OR
in the mid to upper 90s. Temperatures will decrease by 2 to 5
degrees by Thursday as the trough sweeps across and temperatures
will remain through the period. Remain diligent with the heat.
Find more ways to protect yourself and others at
www.weather.gov/safety/heat. Bennese/90


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT 100  59 102  62 /   0   0   0   0
ALW 103  62 105  64 /   0   0   0   0
PSC 104  64 105  66 /   0   0   0   0
YKM 103  65 105  68 /   0   0   0   0
HRI 104  63 106  64 /   0   0   0   0
ELN 102  62 105  64 /   0   0   0   0
RDM 100  54 101  59 /   0   0   0   0
LGD  96  53  98  58 /   0   0   0   0
GCD  98  56 100  60 /   0   0   0   0
DLS 104  67 108  71 /   0   0   0   0

&&

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

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

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

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

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

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

&&

$$

SHORT TERM...82
LONG TERM....90
AVIATION...87