Area Forecast Discussion
Issued by NWS Spokane, WA

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965
FXUS66 KOTX 220045
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
545 PM PDT Mon Jul 21 2025

.KEY MESSAGES...

- Showers and thunderstorms with heavy rain this evening. Heavy
  rain will increase the potential for flash flooding near burn
  scars.

- Isolated to scattered thunderstorms region-wide Tuesday.

- Warmer with breezy winds Thursday and Friday.

&&

.SYNOPSIS...
Slow moving showers and thunderstorms will impact the northern
mountains this evening. Heavy rainfall will be the main concern
with these storms. Showers and thunderstorms will develop again
Tuesday across the Inland Northwest. A warming and drying trend
will prevail Wednesday into Friday with breezy conditions
returning Thursday and Friday.

&&

.DISCUSSION...
Tonight and Tuesday: Upper-level low has tracked into southern WA
and will begin to slowly eject to the east on Tuesday. Moisture
indices have been on the increase throughout the previous 24
hours with the 18z balloon data now showing almost 0.90" of
precipitable water. Sunbreaks over Central and Northern WA will
continue to fuel pulse thunderstorms with torrential downpours
and lightning as the main threat. Spotters this afternoon have
reported 0.50" in 30 min under some of the heavier cells. This
threat will continue until sunset then wane into decaying
showers. For Eastern WA and North Idaho, the thick blanket of
clouds currently over the area will begin to slowly break up.
This will bring a late day, small threat for some convective
cells and a few thunderstorms. Best chance for organized
thunderstorms this evening will be south of this cloud shield
stretching from northeastern Oregon to Missoula. A few of these
cells containing hail, gusty winds, and heavy downpours still
have a 30% chance to skirt southern Asotin and Lewis Counties
per the latest HRRR mainly before 9PM. Otherwise, scattered
showers will rotate across northern WA through the night with
generally light precipitation intensities.

On Tuesday, showers wrapping around the backside of the low will
pass through E WA and N ID in the morning then afternoon
heating will promote afternoon instability with surface based
CAPEs increasing between 500-1000 J/kg and CAPE through a deeper
layer reaching -20C to -25C. This will bring the potential for
a few stronger cells containing a combination of heavy rain and
hail. Effective shear will be the limiting factor for organized
updrafts as it only increases near 15kts. Higher CAPEs will
compensate some and many hi-res models indicate a few cells
tracking west to east through the northern tier of WA and N ID
Tuesday evening that would likely need to be close attention to.
This includes most communities along and north of Hwy 2
including Spokane-Cd`A. Isolated t -storms cannot be ruled out
around Wenatchee, Moses Lake, and into Ritzville as well. Threat
seems lower for Pullman, Lewiston, and Deary. Storms on Tuesday
will also bring the potential for scattered to potentially
frequent lightning strikes given the deeper instability into the
ice growth zone.

Wednesday through the weekend: There is good agreement in the
ensemble clusters for weak ridging Wednesday which begins to
flatten Thursday. A trough settles into the West Coast Friday
into the weekend with tendency to retrograde by Sunday and
Monday placing the Inland in southwest flow aloft. Wednesday`s
flat ridge will deliver drier conditions and warming
temperatures. Cumulus buildups are expected on the tail end of
the departing low over North Idaho with a 20% chance for very
light showers with little to no rainfall. Temperatures continue
to warm on Thursday and remain in the 80s to lower 90s Friday
with breezy conditions and elevated fire weather conditions. NBM
introduced 20-40% chances for wind gusts of 30 mph in the lee
of the Cascades and foothills of the Blue Mountains. Otherwise,
wind gusts across much of the region will be in the 15-25 mph
range. As the trough sets up along the WA Coast, there will be
10-20% chances for afternoon convection over the mountains near
the Canadian border though this comes with low confidence for
cells to set up south of the International border. All things
considered, the Inland NW will be entering another dry period
with warm temperatures and periods of breezy winds. /sb

&&

.AVIATION...
00Z TAFS: A low pressure system spinning over eastern Washington
will bring passing showers. Some stronger cells primarily over
the mountains will have embedded thunderstorms. Coverage of
convection this afternoon will decrease into the overnight hours
with the loss of surface heating. The atmosphere will remain
conditionally unstable on Tuesday under the trough of low
pressure. Models indicate better instability with more potential
for thunderstorms. Not enough confidence at this point to add
thunderstorms to the TAFs. Generally light and variable winds
across the region except for where convective outflows occur
with convective cells.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
for VFR conditions. The exception will be where covective cores
pass through that may briefly drop visibility below 6 SM with
MVFR conditions. There is a 15% chance for thunderstorms at
KEAT-KGEG-KSFF-KCOE-KLWS this evening, and less than 10% chance
at KMWH and KPUW. /SVH

&&

.Preliminary Point Temps/PoPs...
Spokane        57  78  56  87  60  90 /  40  50  20   0   0   0
Coeur d`Alene  56  77  54  86  59  89 /  50  60  30   0   0   0
Pullman        49  77  50  83  53  87 /  30  30  10   0   0   0
Lewiston       62  87  62  93  65  97 /  40  20  10   0   0   0
Colville       47  74  45  84  48  88 /  70  70  30  10   0   0
Sandpoint      52  70  49  81  54  85 /  70  80  50   0   0   0
Kellogg        56  70  56  81  61  86 /  60  70  40   0   0   0
Moses Lake     57  85  59  92  60  94 /  30  10  10   0   0   0
Wenatchee      62  85  64  92  66  93 /  50  40  20   0   0   0
Omak           58  85  58  92  60  94 /  60  40  10   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Flood Watch until 9 PM PDT this evening for Central Chelan
     County-Okanogan Highlands-Okanogan Valley-Wenatchee Area-
     Western Chelan County-Western Okanogan County.
ID...None.

&&

$$