Wildfire in Washington, June 24 to 25, 2023

Area Forecast Discussion
National Weather Service Spokane WA
401 PM PDT Sat Jun 24 2023

.SYNOPSIS...
A low pressure trough with passing weak disturbances will keep a
chance for showers and thunderstorms at times through the weekend
and into next week. Best chances for showers will be over the
mountains. Temperatures will see a very gradual warming trend this
weekend and next week to above normal readings.

&&

.DISCUSSION...

Tonight through Monday Night: An upper trough will continue to
linger over the region into Sunday, before a low closes off over
Oregon on Monday. Net result in light steering flow over the
region with continued moisture, resulting in slow moving showers
and thunderstorms mainly over the higher terrain each day. A flood
watch remains in effect for mainly the burn scars in Okanogan
county through 8 PM PDT this evening. The air mass under this
trough remains warm due to relatively high heights over the
region. The warm air mass combined with dewpoints in the 40s is
resulting in large temperature/dew point spreads this afternoon of
35-45F. This will lead to enhanced wind gust potential out of
these storms in and near the Cascades, as well as down by the
Lewiston area through the evening. CAM's models are showing
potential wind gusts ranging from 25-35 MPH. With lack of large
scale lift this activity is expected to end with the loss of
daytime heating after sunset. On Sunday and Monday a near repeat
performance is expected. We will have to keep an eye on the burn
scars for the next several days due to continued high precipitable
water and slow storm motion. The good news is that with the weak
shear environment the storms have tended to only last 15-30
minutes before weakening and suspect a similar performance on
Sunday.  JW

Tuesday to Saturday: The Inland Northwest will remain unsettled
through the middle of the week, before the precipitation chances
start to retreat toward the east. A trough lingers over the the
western United States with instability showers and thunderstorm
chances each afternoon through Wednesday. The best 0-6km shear is
near the Cascades, but it is still only about 20-25kts; so the
potential for organized t-storms is not high. However PWATs rise
to around 140-170% of normal or around 1 inch and models show a
decent amount of SBCAPE at 300-850 J/kg in the afternoon hours. So
these showers/t-storms will continue carry the potential for brief
heavy downpours. We may have to monitor for localized flooding,
especially north and near burn scars. T-storms could also produce
small hail and the obvious lightning potential. The risk for these
will wane each evening with the loss of daytime heating. Thursday
to Saturday the PWATs start to decline so that by Friday into
Saturday they are around 60-100% of normal. The main trough starts
to shift east, but a long-wave trough over northeast Pacific/Gulf
of AK sends some impulses into the region. Shower and t-storm
chances will continue over the NE WA and ID Panhandle mountains
Thursday afternoon and then primarily near the north ID Panhandle
for Friday afternoon, with ensemble probabilities for measurable
precipitation (at least 0.01") dropping to around 20-30% in that
area and 10% or less elsewhere. The dry weather remains in the
forecast for Saturday. Temperatures are expected to sit slightly
above normal around mid-week, with areas then warming into the
upper 80s to mid-90s later in the week. Look for a bit of
afternoon breeziness, especially later in the week and toward the
western zones and deeper basin as the cross-Cascade flow
increases. Gusts in the 15-20 mph look like the more likely wind
gust potential at this point. /Solveig

&&

.AVIATION...
00Z TAFs: Thunderstorms over the mountains will continue to
produce locally gusty winds up to 30 MPH into the early evening
near the Cascades and around the Lewiston area. The storms will
dissipate this evening with the loss of daytime heating. Another
round of showers and thunderstorms will develop over the mountains
on Sunday afternoon with the greatest focus over the North
Cascades and Okanogan Highlands. There will be a 40 percent
chance of showers and thunderstorms in the Methow Valley, 30
percent around Republic and Omak, and a 20 percent chance in
Wenatchee and Chelan. Storms will also be capable of producing
outflow wind gusts up to 30 MPH. JW

&&

.PRELIMINARY POINT TEMPS/POPS...
Spokane        53  84  56  85  57  84 /   0   0   0  10  10  10
Coeur d'Alene  53  82  55  84  57  83 /   0   0  10  10  10  20
Pullman        54  80  54  81  54  80 /  10  10   0  10  10  10
Lewiston       60  88  62  91  63  88 /  20  10   0  10  10  20
Colville       48  82  51  84  54  84 /  10  20  10  20  10  30
Sandpoint      51  80  53  82  54  80 /  10  10  10  20  20  30
Kellogg        56  78  57  79  58  76 /  10  20  10  20  10  30
Moses Lake     54  88  57  90  59  89 /   0   0   0   0  10  10
Wenatchee      60  86  63  87  64  87 /  10  20   0  10  10  10
Omak           56  86  59  90  60  90 /  20  30   0  20  10  30

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flood Watch until 8 PM PDT this evening for Okanogan Highlands-
     Okanogan Valley-Western Okanogan County.

&&