887
FXUS66 KOTX 300538
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
1038 PM PDT Tue Jul 29 2025

.KEY MESSAGES...

- High Temperatures 90s to 100s through Thursday with Moderate
  and Major HeatRisk.

- Isolated dry thunderstorms Wednesday. Scattered, wet and dry
  thunderstorms on Thursday and scattered, wet thunderstorms on
  Friday.

- Gusty winds and lightning primary hazards for Wednesday into
  Thursday with a transition to heavy rainfall, hail, and gusty
  winds Thursday afternoon into Friday.

&&

.SYNOPSIS...
Temperatures be very warm through Thursday with highs in 90s
and low 100s. Isolated dry thunderstorms on Wednesday over the
mountains will bring a risk for new fire starts. There are
increasing chances for wet thunderstorms with gusty winds and
isolated hail Thursday and Friday.

&&

.DISCUSSION...
Tuesday night through Friday: A deep upper-level closed low remains
nearly stationary in the Gulf of Alaska as the upper-level ridge
over the Inland Northwest amplifies. It will be quite warm through
Thursday with lows in the 60s and 70s and highs in the 90s to low
100s. Widespread Moderate and Major HeatRisk will bring the risk for
heat-related illnesses those without adequate cooling, but
thankfully this heat looks short-lived with temperatures cooling on
Friday.

Increasing southerly flow tonight will allow for elevated moisture
to begin advecting into the Inland Northwest. SBCAPE increases to
500-1500 J/kg across the Cascades, northeast and southeast with
Washington and the Idaho Panhandle Wednesday afternoon combined with
-30 to -75 of SBCIN. Weak lift will limit overall convection
initiation, with CAMs showing cells developing primarily over the
mountains (Cascades, Okanogan Highlands, northeast Washington, Idaho
Panhandle) Wednesday afternoon. Stray cells will be possible (10-20%
chance) over the Spokane/CdA metro area, but this carries low
confidence. Forecast soundings depict inverted-V soundings with very
dry sub-cloud layers, which would support little precipitation and
gusty outflow winds.

For Thursday, models continue to show a more organized shortwave
slowly moving northward across Oregon on Thursday and moving
into eastern Washington and north Idaho Thursday afternoon and
evening. The airmass will become increasingly moist as the
shortwave moves into Washington on Thursday with PWATs
increasing to 1-1.25 inches (150-200% of normal) by late
Thursdaymorning. Initially, impulses ahead of this shortwave
bring a 15-20% chance for elevated thunderstorms over the
central Washington Thursday morning, supporting a mix of wet and
dry thunderstorms. Increasing instability for Thursday
afternoon and evening with additional impulses moving in the
Inland Northwest will expand the thunderstorm potential (25-50%
chance) to the entire region. Weak steering flow and inverted-V
soundings on Thursday suggest the primary hazard to be heavy
rain and gusty outflow winds (DCAPE >800 J/kg). The best shear
(25-30 knots of 0-6km) will be across southeast Washington and
the southern Panhandle which could support more organized,
longer- lived thunderstorms and hail. Any showers that form over
burn scars and steep terrain will bring a threat of debris
flows.

For Friday, the shortwave will slowly continue northward with the
best chances (30%) for thunderstorms shifting to the northern
mountains and the Idaho Panhandle. Further moistening of the
boundary layer will to support slow-moving thunderstorms with a 55-
65% chance for rain totals greater than 0.25 inches. This will bring
a continued threat of flash flooding and debris flows in steep
terrain and burn scars. Temperatures on Friday will cool by 10-15
degrees.

Saturday and Sunday: The deep upper-level low in the Gulf of Alaska
looks to begin shifting eastward with a return to southwest flow
aloft. There is uncertainty in the ensembles with how the track and
strength of this low and an additional shortwave south of this low
will evolve as they travel eastward. but current forecast leans
toward temperatures trending back to near normal values (80s to low
90s) for the weekend. /vmt

&&

.AVIATION...
06Z TAFS: VFR conditions will continue with some high clouds
moving across the region from the south. Winds will be light and
terrain driven through the period. Low chance of thunderstorms
this morning around Lewiston and southward but not high enough
confidence to include in the KLWS TAF.

Moderate confidence in thunderstorm chances increasing across
the forecast area around 20-21Z, but there is not enough
confidence to put TS in specific TAFs at this time. These
thunderstorms are anticipated to be dry so main concerns include
localized gusty outflow winds and lightning strikes. Main areas
that could see thunderstorms include the Cascades, Okanogan
Highlands, Northern Mountains, and the northern Idaho Panhandle.
The Spokane area, Upper Columbia Basin, and the Lewiston area
and southward could see a few cells but guidance right now
favors most cells in the mountains.


FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
in VFR conditions through the TAF period. Low confidence in
morning thunderstorms, and moderate confidence in afternoon
thunderstorms.

&&

.FIRE WEATHER...
A Red Flag Warning is in effect for Fire Weather Zone 696 from
Wednesday 1 PM to 9 PM due primarily for hot and unstable
conditions. Southerly flow will allow for elevated moisture to
advect into the Cascades with PWATs increasing to 0.60-0.70
inches (~120%) of normal on Wednesday. Very warm temperatures
with highs in the 80s and very steep low level lapse rates
(8-10C/km) will support deep mixing with mixing heights 12k-13k
feet AGL over the Cascades. This will increase the risk of
active fire behavior for the Pomas Fire and any new fires
Wednesday afternoon and evening. Additionally, there will be a
small risk (15%) chance for isolated thunderstorms. The
boundary layer will be very dry on Wednesday with deep
inverted-V soundings that support mostly dry thunderstorms if
development occurs. These sounding profiles also indicate the
potential for gusty and erratic outflow winds, as precipitation
from elevated storms evaporates aloft and the rain-cooled air
descends into a hot, dry airmass below.

&&

.Preliminary Point Temps/PoPs...
Spokane        64  97  67  97  64  84 /   0  20  20  10  40  40
Coeur d`Alene  65  96  66  97  64  83 /   0  10  10  10  40  50
Pullman        59  95  61  92  58  80 /   0   0  20  10  50  40
Lewiston       69 103  71 100  69  90 /   0   0  10  10  50  50
Colville       54  96  56  97  54  84 /   0  30  10  10  40  60
Sandpoint      60  92  61  93  59  80 /   0   0  10  10  40  70
Kellogg        67  93  68  94  64  79 /  10   0  20  10  50  60
Moses Lake     63 101  68 100  66  88 /   0   0  10  10  30  20
Wenatchee      72 100  76  98  72  87 /   0   0  10  30  30  40
Omak           67 100  69 101  67  87 /   0   0  10  20  30  50

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
WA...Red Flag Warning from 1 PM to 9 PM PDT Wednesday for East
     Washington Central Cascades (Zone 696).
ID...None.

&&

$$