103
FXUS66 KOTX 120947
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
247 AM PDT Sun May 12 2024

.SYNOPSIS...
Today will once again be warm, with highs reaching the 80s and a
few areas in the lower 90s. An approaching system will increase
the breeziness this afternoon and Monday, especially closer to the
Cascades and western Columbia Basin. A chance for showers will
come to the Cascade crest, northeast Washington and the northern
Idaho Monday, lingering over Idaho Tuesday. Temperatures will cool
for Monday and Tuesday, rebound around midweek, then decrease
again later in the week as the next shower and breezy winds
chances come in.

&&

.DISCUSSION...
Today through Tuesday: The Inland NW will experience once more
warm day, before a system moves in and cools thing at little bit,
with localized shower chances and gusty winds. Today the axis of
the ridge of high pressure will shift east, while the first
shortwave moves in from the west. The ridge will continue to
provide mostly dry conditions and temperatures reaching the upper
70s and 80s, along with a few areas approaching 90 in the deeper
Columbia Basin. The approaching shortwave will enhance the onshore
flow, leading to slightly cooler readings in the Cascades and
some afternoon breeziness.

Then tonight into Monday morning the first shortwave moves
through the region, followed by a second shortwave trough on its
heels Monday afternoon and evening. The first wave will lead to
more clouds and very limited shower chances near the immediate
Cascade crest and Canadian border. Winds will also increase more
noticeably near the Cascades into the Waterville Plateau early
this evening, with speeds near 15-25 mph, with gusts near 30-40
mph. Areas just downwind of the Blue Mountains will see some winds
near 15 mph and gusts of 20-30 mph. Speeds abate a little
overnight into early Monday.

The second wave moving in will keep shower chances alive near the
Cascade crest through afternoon and bring broader shower chances
across northeast WA and the north and central ID Panhandle,
including skimming by the northeast Spokane county area into the
CdA area. As that wave sags through in Monday evening it will draw
more clouds south and east and, per some guidance, expand shower
chances over more of the Spokane/CdA area and possibly as far
south as far northern Whitman county. No all guidance is in agree
with this precipitation scenario but the risk seems enough to
warrant at least a slight chance in these ares. Either way
precipitation amounts mostly look light. The exception could be in
the northeast WA mountains and north ID where some embedded
t-storms are possible Monday afternoon and evening. Winds will
pick up across the region Monday afternoon and evening. The
strongest speeds will continue near the Cascades and Waterville
Plateau at 15-30 mph and gusts of 35-40 mph. Elsewhere speeds of
10-20 mph and gusts 15-25 mph will be possible, especially
unsheltered areas.

Heading into Monday overnight into Tuesday the shortwave moves
east, leaving the area in a northeast flow and shifting the
primary shower chances to the northern and central ID Panhandle.
Winds remain breezy overnight with some decline toward day break,
before the pick up again in the afternoon over some the area. The
breezier conditions by Tuesday afternoon will be down the Okanogan
Valley into the Waterville Plateau, with winds changing from
westerly to more northerly with speeds of 10-20 mph and gusts of
25-30 mph.

Temperatures will be cooling to the upper 60s and 70s, with a few
low 80s in the deeper Columbia Basin and L-C Valley for Monday
and Tuesday, with overnight lows in the 40s to low 50s. /Solveig

Tuesday night through Saturday: Models are in good agreement for the
upper level ridge to at least temporary rebound over the Inland
Northwest on Wednesday. This will allow temperatures will warm
back into the upper 70s to mid 80s by Wednesday afternoon.

By Thursday, there still exists a lot of uncertainty in the
evolution of the ridge. While models do agree on the initial rebound
of the ridge on Wednesday, there are many opposing solutions on
the impact an upper level trough will have on it as it passes
through British Columbia on Thursday. 55% of ensembles out of a
100 ensemble suite show a deeper trough to move into the
northwest. However, among these ensembles, there are varying
possibilities on the overall strength of this trough. In general,
this would deflect the ridge to our south, bringing temperatures
down into the 50s and 60s on Thursday, breezy winds, and chances
for precipitation. A weaker trough would be a slightly "warmer"
solution, with breezier winds and less precipitation. A faster
moving, stronger trough solution would result in much cooler
temperatures, better chances for widespread preciptiation, and an
earlier onset of breezy winds.

Meanwhile, the other 45% of ensembles show a ridge remaining in
place, with less of an influence from the trough as it passes to our
north. Again, among these ensembles, there are varying degrees on
the strength of this ridge. A stronger ridge would would keep
temperatures in the 70s and 80s with clear skies and dry weather.
However, a weaker ridge would still allow there to be some influence
from the trough to our north, with these solutions showing breezy
winds and slightly "cooler" temperatures compared to the strong
ridge. Because of this, the forecast for Thursday and beyond will
change several times over the next couple of days as models begin to
trend toward a consensus.

Uncertainty in the forecast continues Friday through the weekend
with the potential for additional systems to pass through the Inland
Northwest. Models show a gradual decline in temperatures through
the weekend continuing into early next week, but the exact numbers
carry very low confidence at this time. /vmt

&&

.AVIATION...
12Z TAFS: High pressure starts to weaken and a shortwave system
starts to move int tonight. However VFR conditions expected at TAF
sites. A few more clouds are possible over the northern mountains,
with some fair cumulus build-ups in the afternoon, with isolated
shower chances near the Canadian border for this evening and
overnight. Winds increase this afternoon with gusts near 15-20 mph
in the 1300-1900 PDT time frame for most place. The exception
will be near the Cascade, including EAT where winds will remain
breezy through the night with gusts near 20-30kts possible. There
will be risk for LLWS as a low level jet strengthens in advance of
the shortwave, with the potential near PUW, MWH and, if the
mixing decouples, near EAT.


FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
There is high confidence in VFR conditions. Low confidence in
showers and precise timing of winds near the Cascades and EAT, as
well as low to moderate confidence in LLWS overnight/early Monday
near PUW, MWH and EAT.

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

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        82  51  75  47  75  49 /   0   0  10  20  10   0
Coeur d`Alene  80  51  73  47  71  47 /   0   0  20  20  10   0
Pullman        77  51  70  46  69  47 /   0   0   0  10  10   0
Lewiston       85  54  79  52  77  52 /   0   0   0  10  10   0
Colville       83  48  76  45  77  45 /   0  10  20  20  10   0
Sandpoint      78  50  70  48  69  46 /   0   0  30  30  20   0
Kellogg        76  53  68  49  68  49 /   0   0  20  20  20   0
Moses Lake     88  53  79  48  80  51 /   0   0   0   0   0   0
Wenatchee      86  56  74  50  80  54 /   0   0   0   0   0   0
Omak           89  53  79  48  81  51 /   0   0  10  10   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&

$$