702
FXUS66 KOTX 071001
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
301 AM PDT Sun Jul 7 2024

.SYNOPSIS...
Weather conditions are expected to be hot and dry the next seven
days. Winds will be light through Tuesday. Breezy to gusty winds
return Wednesday with increasing fire weather concerns.

&&

.DISCUSSION...

...SIGNIFICANT HEATWAVE TO IMPACT THE INLAND NW THIS WEEK...

Key messages for the week

- Hot to very hot temperatures will be in place through Wednesday
  increasing the risk for heat related illnesses
- Tuesday and Wednesday will deliver the hottest afternoon
  temperatures and warmest overnight lows
- No precipitation is in sight throughout the week
- Smoke from the Pioneer fire will impact air quality around
  Lake Chelan and nearby communities at times
- The weakening of the heat on Wednesday will bring breezy to gusty
  winds increasing fire weather concerns
- Prior to Wednesday, the heat + drying of fuels coupled with an
  unstable atmosphere will result in elevated fire weather conditions
- Temperatures cool 10 degrees Thursday then look to slowly warm
  again heading into next week prolonging the risk of above normal temperatures

Sunday through midday Wednesday:  A significant heatwave is poised to impact
the Inland Northwest this week delivering widespread triple digit
heat. Confidence has not changed and remains high with very
little spread in the models. High temperatures will warm from the
90s to lower 100s Sunday to 100`s Monday, Tuesday, and Wednesday.
Tuesday and Wednesday will feature the hottest readings of this
heatwave with numerous communities between 105-110F. Excessive
heat warnings are meant to capture the areas that will carry the
greatest risk for overnight lows of 65-75F offering little to no
relief at night. Valleys of NE WA and N ID carry a higher
probability of cooling into the 50s to 60s which has led to
advisories vs warnings. The heat is courtesy of a anomalously
strong upper-level ridge of high pressure that promotes subsidence
and atmosphere warming and also allows the heat that has been
festering across the Southwest to expand northward. Keep the sun
glasses handy as any moisture or cloud cover for that matter will
be deflected well around the Northwest.

The Pioneer Fire burning south of Stehekin on Lake Chelan will have high
probabilities to remain active given the projected weather
pattern. Smoke from the fire will settle into the lake basin
overnight with a drift downlake toward Manson and Chelan overnight
and uplake during the day. Deeper plumes of smoke during the day
will bring the potential for smoke into the Methow Valley as well.
Air quality is likely to be impacted at times. Please refer to
fire.airnow.gov for the latest readings and smoke outlooks.

Wednesday afternoon through Saturday: Changes arrive in this period with
the initial blow and flattening of the upper-level ridge. This
will usher a dry "cool" front through the region with the most
impactful element coming as breezy to gusty winds. This has been
advertised for a few days and confidence is starting to grow.
Strongest winds look to channel through the Cascade Gaps and spill
into the Western Columbia Basin but an increase in winds will
definitely be noticeable for many across the Eastern Basin,
Spokane-Cd`A Area, Palouse, and L-C Valley. Uncertainty right now
is whether these eastern zones will experience strong enough wind
speeds for any fire weather highlights. The highest probabilities
for sustained winds greater than 15-20 mph are focused around
Chelan, Wenatchee, Waterville, Wilbur, Ephrata, Moses Lake, and to
some degree Ritzville (40-70%) and continue to increase with each
run. The eastern Basin (Spokane to Pullman to Lewiston) are close
to 10-20% at this time. Nonetheless, any wind will be a major
concern with temperatures in the 100s, RH in the teens, and
following an extended period of hot weather.

Temperatures will be 10-15 degrees cooler on Thursday with a flatter
ridge in place but still 10 degrees above normal as readings
remain in the 90s. The air mass also becomes quite dry behind the
front with PWATs lowering from 0.50 to 0.25 Wednesday night and
Thursday so despite the cooling, RH values will remain very low.
The good news, if the winds can calm overnight, the drier air
should allow for more adequate cooling at night. Friday will
feature similar afternoon readings then the thermometer will be on
the rise again for the weekend. How warm? This comes with a
moderate amount of uncertainty. Models are having a hard time
resolving the placement of an offshore low and the interior ridge
which is impacting temperatures. It is conceivable that
temperatures rebound back into the upper 90s or even lower 100s.
When this offshore low rotates inland some point early next week,
will be keeping a close eye on the bout of wind and potential for
lightning. /sb

&&

.AVIATION...
06Z TAFS: VFR conditions will prevail, except near the Pioneer
Fire (Lake Chelan area). Smoke aloft (haze) from the fire will
spread into portions of Central WA so retained a FEW200 group for
KEAT/KMWH. Strong high pressure will result in terrain driven
winds of 10 kts or less through Tuesday. JW

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence in
VFR conditions. Low confidence for localized visibility
reductions due to smoke.

-----------------------

Confidence descriptors:
Low - Less than a 30 percent chance
Moderate - 30 to 70 percent chance
High - Greater than a 70 percent chance

For additional probabilistic information for NWS Spokane airports,
please refer to the Aviation Dashboard on our webpage:
https:/www.weather.gov/otx/avndashboard

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        96  67 100  69 103  70 /   0   0   0   0   0   0
Coeur d`Alene  92  63  97  67 100  68 /   0   0   0   0   0   0
Pullman        93  60  96  63 100  65 /   0   0   0   0   0   0
Lewiston      101  70 105  72 108  74 /   0   0   0   0   0   0
Colville       93  57  98  60 101  61 /   0   0   0   0   0   0
Sandpoint      89  57  93  60  97  63 /   0   0   0   0   0   0
Kellogg        88  65  94  68  98  70 /   0   0   0   0   0   0
Moses Lake    101  65 104  68 108  72 /   0   0   0   0   0   0
Wenatchee     101  74 105  76 107  77 /   0   0   0   0   0   0
Omak          102  70 105  72 107  73 /   0   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Heat Advisory from noon today to 10 PM PDT Friday for Central
     Panhandle Mountains-Northern Panhandle.

     Excessive Heat Warning until 10 PM PDT Friday for Coeur d`Alene
     Area-Idaho Palouse-Lewis and Southern Nez Perce Counties-
     Lewiston Area.

WA...Heat Advisory from noon today to 10 PM PDT Friday for Northeast
     Mountains-Okanogan Highlands.

     Excessive Heat Warning until 10 PM PDT Friday for Central Chelan
     County-Lower Garfield and Asotin Counties-Moses Lake Area-
     Northeast Blue Mountains-Okanogan Valley-Spokane Area-Upper
     Columbia Basin-Washington Palouse-Waterville Plateau-
     Wenatchee Area-Western Okanogan County.

     Heat Advisory until 10 PM PDT Friday for Western Chelan County.

&&

$$