309
FXUS66 KOTX 161007
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
307 AM PDT Fri Aug 16 2024

.SYNOPSIS...
Thunderstorms will return today across the northern mountains
with concerns for flash flooding over burn scars. More showers and
thunderstorms are possible Saturday evening and night for central
WA. Temperatures will be warmer on Saturday with dry and breezy
northeast winds across the Columbia Basin, West Plains, and
southeast Washington.

&&

.DISCUSSION...
Today through Saturday Night: Trough is swinging through the
region providing isolated to scattered showers across the
US/Canadian border, eastern WA and north ID. There have been a few
lightning strikes through the night, but they have been very
isolated in nature. The trough will continue to move north through
the day. Surface instability will increase through the afternoon
and bring a chance of additional showers and thunderstorms through
the evening. Precipitable water values increase to about 150% of
normal this afternoon across the north. In addition, there is good
deep instability and very light winds throughout the vertical
profile, looking at several soundings. Any storms that develop
will be slow moving. This raises concern for flash flooding and
debris flows from heavy rain from slow or stationary storms,
especially over current and recent burn scars. Will continue the
flash flood watch for Chelan and Okanogan counties for this
afternoon and evening.

Showers and thunderstorms will move out of the region this evening
with a quiet period through Saturday afternoon. Mostly sunny skies
Saturday with a shortwave ridge pumping up into the region briefly
will allow temperatures to warm into the mid 80s to mid 90s, which
is 4 to 8 degrees above average.

The low that is sitting off the coast will push a wave up into
Oregon Saturday afternoon. We will be keeping a close eye on
this. Models are suggesting clouds will increase in the late
afternoon across central WA. Good forcing with this wave and
elevated instability will move in during the evening and bring a
threat of showers and thunderstorms to mainly central WA through
the night. Have mention of showers further east into eastern WA
and north ID through the overnight hours, but wasn`t confident
enough at this time to add thunderstorms. Higher confidence is
across central WA. The concern with the thunderstorms will be
gusty outflow winds and lightning through the night. /Nisbet

Sunday through Friday: Unsettled conditions remain as the upper
level low meanders off the Washington coast. Chances for
showers/thunderstorms will linger into Sunday across the Cascades
and northern mountains (10-20%). By next Friday, ensembles have
the trough axis in nearly the same place! What is particularly
remarkable about this stretch of weather is the strength of the
desert southwest ridge. It is one of the strongest ridges in the
last 20 years for August for the southwestern United States.
Despite the Inland Northwest being influenced by the trough
offshore, the strong high pressure in the southwest will help us
sustain above average temperatures for much of next week. Models
do suggest a small break from the warmth Thursday as a negative
tilt shortwave comes ashore, which also signals greater
thunderstorm potential by Wednesday. /Butler


&&

.AVIATION...
06Z TAFS: An upper level low is currently passing from South to
North across the Idaho Panhandle. The thunder activity has
decreased across the region and have been removed from the
forecast area for tonight. Rain showers will continue to be an issue.
Moderate rain with lowering ceilings is expected across the
northern Idaho Panhandle into northeast Washington overnight into
Friday morning. Thunderstorms will begin across North Washington
late Friday morning and last through the end of the TAF period.
Thunderstorms are not expected to impact TAF sites.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence
for VFR conditions today across the majority of the TAF period.
Low confidence on shower activity impacting TAF sites.


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

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        80  55  90  59  86  57 /  30   0   0  20   0   0
Coeur d`Alene  76  54  87  58  84  56 /  50  10   0  20   0   0
Pullman        78  52  90  53  84  53 /  20   0   0  20   0   0
Lewiston       86  62  98  65  92  63 /  10   0   0  10   0   0
Colville       78  44  87  48  85  47 /  50  20   0  40   0   0
Sandpoint      72  50  84  55  83  53 /  80  10   0  20  10  10
Kellogg        74  57  86  60  83  60 /  60  10   0  20  10   0
Moses Lake     84  54  94  59  86  55 /  10   0   0  50   0   0
Wenatchee      84  62  90  63  84  62 /  10   0   0  60  10   0
Omak           86  58  94  63  90  58 /  40  10   0  60  10   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...Flash Flood Watch from 11 AM PDT this morning through this
     evening for Central Chelan County-Okanogan Highlands-
     Okanogan Valley-Upper Columbia Basin-Wenatchee Area-Western
     Chelan County-Western Okanogan County.

&&

$$