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000
FXUS66 KOTX 131036
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
336 AM PDT Sat Apr 13 2024

.SYNOPSIS...
Expect an unseasonably warm weekend across the Inland Northwest.
High temperatures for the next two days will generally be more
typical for what we would expect to see in early June. Most
locations will be dry, however there will be a small chance of
showers and thunderstorms over extreme southeast Washington and
the southern half of the Idaho Panhandle on Sunday afternoon and
night. A cold front will bring a return of cooler, showery
weather early next week. The front will bring breezy. conditions
Sunday night through Monday.

&&

.DISCUSSION...
Today...The weekend will kick off with weather more
typical for early June. The reason for the warm weather will be
directly related to an anomalously strong upper level low just
west of the Bay Area. This low is expected to drift slowly to the
south-southeast through the day. The positioning of the low will
build a shortwave ridge over the area over much of the Inland NW
today...with the upper level jet poised over central BC. This
ridge will slowly warm the lower atmosphere...with 850 mb
temperatures climbing into the 10-12c range or several degrees
warmer than yesterday. This will equate to high temperatures in
the upper 60s to middle 70s today. As for the chances of
precipitation, it appears it should be considerable less than
yesterday. The presence of the shortwave ridge should suppress any
synoptic scale forcing however the 850-500 mb lapse rates are
expected to remain similar to what we saw yesterday. What will
ultimately limit any chances for convection late this afternoon
and evening will be a formidable convective inhibition (CIN) or a
convective cap. If we did see a thunderstorm this afternoon or
evening it would likely occur over the Blue Mountains where the
convective cap is weakest.

Sunday and Sunday night...The latter half of the weekend will be
even warmer for most location as 850 mb temperatures climb another
degree or two with the NorCal upper level low moving inland. The
exceptions will be near the Cascades and through the Columbia
Gorge to the LC Valley which will cool slightly as the flow turns
onshore and deepens the marine layer west of the Cascades. This
deepening will also bring increasing winds initially in the
Cascade gaps by late afternoon overspreading the majority of the
Inland NW overnight care of a strong cold front. Right now we are
expecting to see wind gusts mainly in the 30-35 mph range late in
the afternoon and perhaps approaching 30-40 mph over the Blue
Mountains and western Palouse overnight. The incoming marine layer
followed by the cold front will also lead to an uptick in the
chances for thunderstorms, again primarily over SE Washington and
NC Idaho. The CIN values will be much smaller during this period
while model CAPE values could range from 500-1000 j/kg. Forecast
shear values will pale in comparison to yesterday (20-25 kts on
Sun vs. 50 kts) and consequently we wouldn’t expect to see any
strong storms. The initial threat of convection will initiate due
to the mix of daytime heating, orographic ascent, and low-level
convergence ahead the increasing winds. It looks like this chance
of showers/storms could continue through a good portion of the
evening and perhaps into the early morning hours as a weak upper
level shortwave trough moves in from the west-northwest and feeds
on the moistened air and residual instability. fx

Monday through Friday: Monday will mark the beginning of a
significant pattern change. A trough to our north will send a fairly
strong cold front through the Inland Northwest Monday morning, which
will drop temperatures by 10+ degrees. Accompanying the temperature
drop will be an increase in winds regionwide. Most of the region
will see gusts into the 30s, and gusts upward of 40 mph will be
possible for some of our windier spots including the Waterville
Plateau, exposed areas of the Basin, and Cascade ridge tops.

Behind the cold front, snow levels will plummet, introducing chances
for light snow down to valley floors Tuesday morning. Little to no
lowland accumulations are anticipated, and even for the mountains
the risk of significant snowfall is low. Stevens Pass has a 50%
chance of seeing at least 3 inches, and Snoqualmie has a 80% chance
of 3 inches. If the convergence zone sets up over a pass, heavier
snowfall rates may lead to minor travel disruptions, but generally
roads will be warm enough to mitigate impacts.

Winds on Sunday night into Monday in combination with dry air moving
in from the north will increase grass fire and blowing dust
concerns, particularly for the Waterville Plateau and Columbia Basin.

Temperatures will drop by a few more degrees on Tuesday putting
afternoon highs in the 50s before steadily rebounding through the
rest of the week. Intermittent showers will continue through
Wednesday before things dry out Thursday and Friday. /Fewkes

&&

.AVIATION...
06Z TAFS: Showers and the threat of isolated -tsra will shift
through the southern ID Panhandle, moving east toward MT toward
08-10Z. Mainly middle to high clouds will impact southeast WA and
central and southern ID with this exiting precipitation, thinning
some through the night, with additional high clouds spreading in
through Saturday. Some lower clouds are possible around the
Palouse and L-C Valley in the wake of the precipitation which may
have brought enough boundary layer moisture to bring some local
MVFR cigs, but the better chances are forecast away from PUW/LWS.
So VFR conditions are primarily forecast at TAF sites.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
High confidence in persistent VFR conditions, with low confidence
for possible MVFR cigs around 08-15Z near PUW/LWS.


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

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        71  45  75  43  61  38 /   0   0   0   0   0   0
Coeur d`Alene  70  44  72  43  58  36 /   0   0   0   0   0  10
Pullman        70  47  71  43  56  37 /   0   0  10  10   0  10
Lewiston       75  52  77  48  66  42 /   0  10  20  20   0  10
Colville       71  41  75  42  65  35 /   0   0   0   0   0  10
Sandpoint      67  44  71  43  57  36 /   0   0   0   0  10  20
Kellogg        68  49  72  44  56  38 /   0   0  10  10  10  10
Moses Lake     74  45  79  44  67  40 /   0   0   0   0   0   0
Wenatchee      73  49  77  47  62  40 /   0   0   0   0   0   0
Omak           72  46  77  45  65  38 /   0   0   0   0   0   0

&&

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

$$