248
FXUS66 KOTX 041017
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
317 AM PDT Tue Jun 4 2024

.SYNOPSIS...
A weaker weather system will swing through today with windy
conditions picking up this afternoon. Winds will not be as windy
as Monday. This weather system will also bring additional light
precipitation to the region, especially over the Idaho Panhandle
and into extreme eastern Washington. A significant warming trend
will then commence mid week. Very warm temperatures up into the
mid 80s to mid 90s is expected by Friday into the weekend.

&&

.DISCUSSION...

Today into tonight: A second frontal system will swing through
today. It will bring another healthy plume of moisture to the
Inland Northwest similar in magnitude to the moderate Atmospheric
River event over the past 48 hours. The big difference with this
weather system is that the the track of the surface low will
remain off of the northern BC coastline. Upper level dynamics will
remain well off to the north as a result. Primary forcing
mechanism will be moist isentropic ascent with the warm front that
is beginning to push onshore around 2 AM this morning. Radar will
begin to fill in as warm air advection along the front increases
through this morning. A strong westerly jet aloft will result in a
substantial rain shadow in the lee of the Cascades and across the
basin. Windward slopes of the Cascades will wring out a good
amount of moisture, which will then slop over the crest with
around a half an inch of precipitation expected. Precipitation
will then increase over the Idaho Panhandle where accumulations
will vary considerably as orographics will play a large factor in
which areas will see more than others. The valleys will see up to
a quarter of an inch where the mountains will see closer to around
a half of an inch. Snow levels will be rising up to around 6,000
feet. This should result in snow only over the highest peaks and
unlike to have impacts for even our highest mountain passes (e.g.
Washington Pass and Sherman Pass).

The trailing cold front will swing through in the afternoon. It
will bring a good amount of cold air advection with winds at 850
mbs at around 40-45 mph. We should easily see gusts approaching
these wind speeds with the front moving through during peak mixing
of the day. I increased winds a bit from what was previously
forecast. Winds will be close to advisory criteria and I expect
isolated spots to achieve criteria of sustained winds near 30 mph
and gusting to 45 mph. It`s isolated enough and not near the level
of the winds from yesterday, that elected to not issue a wind
advisory. Impacts will be minor and mainly reserved to strong
cross winds, especially for high profile vehicles. Light weight
objects may be blown around, so hopefully those objects remain
secured after taking action due to the winds from yesterday.

Wednesday through next Tuesday: The longwave pressure pattern will
shift over this period with the Four Corners High strengthening
and becoming more amplified. The ridge axis will build over the
Inland Northwest Wednesday into Saturday. Subsidence under the
ridge will warm temperatures aloft and those warmer temperatures
will translate down to the surface. Expect a warming trend, and
this trend will be significant. We are expected to see the warmest
temperatures of the season thus far and looks to peak on Saturday
with highs around 15 degrees above normal in the upper 80s to mid
90s for most valley locations. Something to keep in mind if
planning outdoor activities over the weekend. Make sure to have a
plan in place to stay hydrated and to seek cooler temperatures,
especially if planning an activity that will be strenuous. Below
are the probabilities for greater than 85, 90, and 95 degrees for
Saturday:

* 85 degrees - Spokane: near 100%, Sandpoint: 65-70%, Omak: near
  100%, Wenatchee: near 100%, Moses Lake: near 100%, Lewiston:
  near 100%, Pullman/Moscow: 55-60%

* 90 degrees - Spokane: 65-70%, Sandpoint: 20-25%, Omak: 90%,
  Wenatchee: 80-85%, Moses Lake: 90%, Lewiston: 90%, Pullman-
  Moscow: 20%

* 95 degrees - Spokane: 25-30%, Sandpoint: near 0%, Omak: 45-50%,
  Wenatchee: 40%, Moses Lake: 50-55%, Lewiston: 45-50%, Pullman-
  Moscow: 0%

Something else that bares watching is the potential for convection
Saturday evening into Sunday. Around 80% of the model ensembles
shows the high pressure ridge axis shifting east of the region at
this time with moisture increasing into the region. Guidance also
indicates a shortwave trough pushing across Saturday evening into
Saturday night. There is uncertainty with the strength of this
wave. Early indications is that it will be fairly weak, but
thermal profiles are favorable for elevated instability to be in
place with the potential for nocturnal convection. The potential
for convection extends into Sunday mainly over the mountains of
northeast Washington and the Idaho Panhandle.

Ensembles begin to diverge more so further into the extended for
next week. The leading consensus is that the ridge will rebound,
but not to the strength of this weekend with temperatures expected
to peak around the middle of next week short of what is
anticipated for this Saturday. /SVH

&&

.AVIATION...
06Z TAFS: West winds have decreased into the 10 to 20 mph range
across the majority of the Inland Northwest after a windy day. Our
next round of light rain will spread east of the Cascades around
12z with the most significant stratiform precipitation occurring
south of Interstate 90. Ceilings of 2000 ft or less are progged by
the HREF and GFS MOS at Pullman, Spokane, and Coeur d`Alene with
the arrival of the light rain. More post-frontal wind will develop
after 21z and persist into the evening with gusts of 25 to 35kts
at Wenatchee, Moses Lake, Spokane, Couer d`Alene and Pullman.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Confidence in ceilings in the 12z-20z time frame are moderate.
Guidance is in good agreement with ceilings between 1000-2000 feet
at GEG, SFF, COE, PUW and smaller airports like Deer Park,
Sandpoint, and Kellogg. However, amendments may be needed to
refine the start and end time of the low clouds. /GKoch

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

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        66  41  69  45  78  51 /  60  10   0   0   0   0
Coeur d`Alene  60  42  67  45  77  52 /  70  20   0   0   0   0
Pullman        63  42  66  44  77  50 /  70  10   0   0   0   0
Lewiston       71  52  77  52  86  59 /  50  10   0   0   0   0
Colville       65  34  69  39  78  45 /  40   0   0   0   0   0
Sandpoint      58  41  66  42  75  49 /  60  40   0   0   0   0
Kellogg        57  46  64  46  76  54 /  90  40   0   0   0   0
Moses Lake     74  43  76  46  85  54 /  30   0   0   0   0   0
Wenatchee      69  45  74  50  83  58 /  40   0   0   0   0   0
Omak           72  41  75  46  83  52 /  20   0   0   0   0   0

&&

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

$$