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000
FXUS66 KOTX 210449
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
949 PM PDT Sat Apr 20 2024

.SYNOPSIS...
A strong cold front arrives this evening and overnight ushering
gusty westerly winds and a chance for brief showers. Sunday will remain
breezy. Mild and dry weather returns for the start of work week
with 60s and 70s by Tuesday. The next cooling trend arrives
Wednesday with small chances for mountain showers.

&&

.DISCUSSION...
Tonight through Sunday night: Current satellite imagery at 2:00
PM this afternoon shows a cold front pushing into western
Washington off of the eastern Pacific. Radar mosaic also shows a
band of showers developing ahead of the front. The atmosphere is
so dry with dew points in the 20s and teens that precipitation is
expected to be fairly spotty with the front as it crosses east of
the Cascades. It will be quite robust and bring strong cold air
advection with 850 mb temperatures dropping 6-8 degree Celsius
from this afternoon into Sunday. The strong temperature drop and
potential for evaporative cooling suggests the potential for
stronger wind gusts with frontal passage. Winds up at 850 mb only
increase up to around 40 mph, some enhancement with the
evaporative cooling could result in gusts up to 45-50 mph for
places. The general consensus is for the potential of these higher
gusts being in the lee of the Cascades, including the Waterville
Plateau, and in the lee of the Northeast Blue Mountains. The
northern portions of the Columbia Basin, into the West Plains and
Palouse region will see the potential for stronger wind gusts
with the passage of the cold front. The timing of the cold front
looks to be between 10pm-12am in the lee of the Cascades late this
evening, and then into the Idaho Panhandle between 2am-4am on
Sunday. It will be during evening to overnight period where we
will see combination of mixing with the front, evaporative cooling
with showers, and a tightening surface gradient for the potential
of stronger wind gusts that may lead to light weight objects
becoming airborne. These stronger wind gusts will be relatively
brief occurring over a span of 2 to 4 hours before remaining
generally breezy through the rest of the morning into the
afternoon hours on Sunday. A wind advisory is in effect between
10pm tonight through 7am Sunday morning. Make sure to secure or
put away objects, such as trampolines, trash cans, and/or patio
umbrellas that may become airborne with sudden gusts of stronger
winds. There is also a small potential for patchy blowing dust
near recently worked fields. Be aware that visibility may drop
suddenly if dirt is picked up by the wind overnight.

By Sunday afternoon, wind gusts will have relaxed a bit to between
30-40 mph over much of the region. We will have lost the potential
for the stronger 45-50 mph wind gusts by this time with our winds
primarily being driven by a tight pressure gradient across the
region. A strong dry slot moving in behind the front will keep us
mostly dry. The exception will be the potential for diurnally driven
showers near the Canadian border over the Northeast Mountains and in
the Northern Panhandle. Temperatures will drop into the 50s for
Sunday for most locations before seeing a rebound next week. /SVH

Monday and Tuesday: Quiet weather is expected for the beginning of
the work week as a subtle ridge shifts over the Inland Northwest.
Widespread temperatures upper 50s to mid 60s on Monday and mid 60s
to low 70s for Tuesday. Widespread near to slightly below freezing
temperatures are expected again for Monday morning and then
retreating to the northeast Washington and Idaho Panhandle valleys
for Tuesday morning.

Wednesday through Saturday: The next system looks to arrive late
Tuesday into early Wednesday, although there remains uncertainty on
the timing and strength of this system. Precipitation will once
again be confined mainly to the mountains with widespread breeziness
expected. This will result in heightened concerns for grass fires
along with blowing dust around recently plowed fields in the
Columbia Basin Wednesday afternoon.

Models keep the region under an unsettled pattern through Saturday
as a broad longwave trough encompasses most of the western United
States. While most models are in general agreement with the
existence of the trough, there are solutions on the exact depth and
position. Because of this there is a high degree of uncertainty on
what this means precipitation wise for the Inland Northwest as
embedded shortwaves rotate around the trough. Right now, nothing is
raising concerns of significant weather impacts. /vmt

&&

.AVIATION...
00z TAFS: A vigorous cold front is sweeping east of the Cascades
now and into the Idaho Panhandle by 1000Z. With the dry air in
place, showers are expected to be primarily right along the front
as it pushes through. Much of the region will remain VFR with
brief MVFR conditions possible at KPUW to KCOE for Sunday
morning. Expect a sharp wind shift from the west and northwest
with gusts to between 25-35 kts with cold front passage. Stronger
wind gusts of 30+ kts will be brief on the order of a few hours.
The stronger wind gusts may bring a brief period of blowing dust
at KMWH. A brief period of low level wind shear will also be
possible right ahead of the front tonight between 06-10Z at KPUW
and KLWS.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence is high
that VFR conditions will prevail. There is low confidence for
blowing dust to reduce visibility at KMWH between 06-09Z tonight.
An alternate scenario includes a 20-30% chance for low stratus or
stratocumulus clouds to result in MVFR conditions at KPUW-KCOE
early Sunday morning.

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

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        37  56  32  60  36  66 /  40   0   0   0   0   0
Coeur d`Alene  36  53  31  58  34  66 /  50   0   0   0   0   0
Pullman        37  52  33  56  35  65 /  30   0   0   0   0   0
Lewiston       45  60  38  64  39  73 /  30   0   0   0   0   0
Colville       33  57  29  62  32  68 /  70  10  10   0   0   0
Sandpoint      36  52  32  57  34  65 /  70  20  10   0   0   0
Kellogg        39  50  34  56  37  66 /  70  10   0   0   0   0
Moses Lake     38  62  34  64  38  70 /  20   0   0   0   0   0
Wenatchee      39  58  37  63  43  67 /  20   0   0   0   0   0
Omak           37  61  34  65  39  70 /  30   0   0   0   0   0

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory from 10 PM this evening to 7 AM PDT Sunday for
     Idaho Palouse.

WA...Wind Advisory from 10 PM this evening to 7 AM PDT Sunday for
     Lower Garfield and Asotin Counties-Spokane Area-Upper
     Columbia Basin-Washington Palouse-Waterville Plateau.

&&

$$