966
FXUS66 KPDT 061023
AFDPDT

Area Forecast Discussion
National Weather Service Pendleton OR
323 AM PDT Sat Jul 6 2024

.SHORT TERM...Today through Monday...An upper level ridge of high
pressure will continue to dominate the synoptic pattern into next
week. The upper ridge will continue to produce hot and dry
conditions throughout the region, with critical fire weather
concerns developing this afternoon. Confidence remains very high
(90-100%) that most of the lower elevation zones across the
forecast area will reach or exceed the 100 degree mark by Sunday.
Temperatures through early next week will continue a warming
trend of 1 to 4 degrees in both high and low temperatures, with
lows in the 60s to low 70s by Monday night. The weak to modest
overnight relief combined with hot afternoon temperatures will
result in HeatRisk values increasing into the high moderate to
locally extreme values, with even moderate to major HeatRisk
developing in most mountain zones. Excessive heat warnings and
heat advisories across most of the forecast area will continue
into portions of next week.

Besides heat, another shortwave trough sliding down the ridge into
the northern Rockies today will tighten pressure gradients in the
area, resulting in breezy conditions across central OR into the
Malheur National Forest further east. The winds combined with
relative humidities in the single digits to lower teens will
result in critical fire weather conditions this afternoon.
Lawhorn/82

.LONG TERM...Tuesday through Saturday...

Bottom Line Up Front

1. HEAT.

2. Breezy conditions return Wednesday.

3. Fire weather concerns Wednesday.


Models are in firm agreement with an upper level ridge continuing to
dominate the region through the midweek. Dry and hot conditions will
persist through much of the long term. High temperatures will
steadily increase through the period with the `hottest` day being
Tuesday followed closely by Wednesday. 89% of the raw ensembles
shows the Pendleton area to be between 100 to 110 degrees with the
NBM putting Pendleton at 108 Tuesday, 110 through the Basin, 105 in
central Wa and 110 through the Gorge. These temperatures are
expected to continue through the work week with confidence in
temperatures staying above or near 100 degrees being high (80-
90%). EFI shows temperatures remaining well above seasonal normal
of nearly 10 to 20 degrees. Looking at the HeatRisk tool, Tuesday
is the day with the highest concern with HeatRisk levels reaching
level 4 or extreme. You can find the definitions of the
categories on the Heatrisk page wpc.ncep.noaa.gov/heatrisk/. With
temperatures remaining above 100 for multiple days and overnight
lows remaining in the upper 60s to low 70s, there is no real cool
off period. Please see weather.gov/safety/heat for tips to remain
safe during remainder of this heat event.

Temperatures may `cool` ever so slightly Thursday with the models in
firm agreement with a shortwave rippling across the region. 70% of
the raw ensembles have the Pendleton area between 90 to 100 with the
NBM showing Pendleton`s high Wednesday to be 98, the Basin at
102/103, Yakima and Kittitas Valleys at 95 as well as the Gorge, and
central OR between 95 and 97 degrees. Along with `cooling`
temperatures, this shortwave will bring with it a tightening of the
pressure gradients at the surface along the Cascades. The pressure
gradient tool is already showing a 9 to 10 mb change and
deterministic guidance shows a tightening along the Cascades. This
will increase the winds through the Cascade Gaps and east slopes of
the OR Cascades. Raw ensembles show a 80% probability of seeing
winds of 15 mph or greater through the Kittitas Valley, the Columbia
River Gorge as well as the foothills of the Southern Blues and
central OR.

Lastly, fire weather concerns will pick up Wednesday as the winds
increase through the aforementioned areas as the shortwave moves
across. While the winds are not entirely `elevated` this still
brings us to the final point. Winds of 15 mph and relative
humidities expected to be in the single digits to below 15% (80-100%
of the raw ensembles show this) across the majority of the region.
With the increase in the winds and the critically low daytime RH
values, there are some fire weather concerns across those areas at
this time with confidence at this time being 60%. Bennese/90


&&

.AVIATION...12Z TAFs...VFR conditions will persist through the period
with mostly terrain driven winds with the exception of a brief
period of elevated winds at DLS/RDM/BDN. DLS will see increased
winds between 00Z and 02Z with sustained winds of 15 kts and gusts
to 25 kts. RDM/BDN will see increased winds between 19Z to 02Z of 15
to 20 kts and gusts of 15 to 25 kts. CIGs will be non-existent with
SKC. Bennese/90


&&

.FIRE WEATHER...Red Flag Warnings remain in effect from 2PM to
9PM today for wind and low relative humidity for fire weather
zones OR610, 611, 640, and 642. Relative humidities in the single
digits to lower teens will combine with breezy winds of 10-20mph
this afternoon, resulting in critical fire weather conditions
conducive to rapid fire spread and extreme fire behavior. Winds
are expected to be lighter Sunday into early next week, precluding
the need of any additional fire weather highlights at this time.
Lawhorn/82


&&

.PRELIMINARY POINT TEMPS/POPS...
PDT  96  62 100  64 /   0   0   0   0
ALW  98  64 102  66 /   0   0   0   0
PSC 101  65 105  66 /   0   0   0   0
YKM 101  63 102  65 /   0   0   0   0
HRI 101  64 105  66 /   0   0   0   0
ELN  98  62 101  66 /   0   0   0   0
RDM 101  56 100  58 /   0   0   0   0
LGD  92  57  96  60 /   0   0   0   0
GCD  96  58  98  60 /   0   0   0   0
DLS 103  68 105  69 /   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 from 2 PM this afternoon to 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...82
LONG TERM....90
AVIATION...90