271
FXUS66 KOTX 301001
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
301 AM PDT Thu May 30 2024

.SYNOPSIS...
Overnight temperatures near to and below freezing are expected
through Friday morning. Drier weather is expected heading into
the weekend except lingering showers over north Idaho today and
light showers mainly over the mountains for Saturday. A dynamic
storm system will push across the region late Sunday into Monday
bringing rain followed by gusty winds and the potential for
afternoon thunderstorms on Monday. Next week will see a warming
and drying trend. Confidence is increasing for temperatures
warming into the 80s and 90s late next week.

&&

.DISCUSSION...

Today and Tonight: Lingering diurnally forced showers are expected
over far northeast Washington and the Northern Panhandle today on
the backside of an exiting upper level trough of lower pressure.
Temperatures aloft will be warming as a shortwave ridge of higher
pressure over the eastern Pacific begins to move onshore. There will
be just enough cooling at upper levels for shallow convection over
the aforementioned areas though. Won`t be enough to get charge
separation for thunderstorms, and precipitation will be light;
unlike yesterday with deeper convection observed across much of
the Inland Northwest. Winds will be less breezy today as well.
Weak winds with clear skies will result in another chilly night
into Friday morning. Current temperature trends are on track with
what was forecast. Valleys across the Okanogan Highlands and
Northeast Mountains are already dipping below the freezing mark.
These areas may be a degree or two warmer Thursday night into
Friday morning, but will once again see a good chance for getting
below freezing. The Freeze Warning looks good and no changes at
this time. Surrounding areas under a Frost Advisory look on track
as well with temperatures trending into the the lower to mid 30s.
I anticipate that these areas will see frost formation again early
Friday morning and we may need to extend part if not all of the
zones another 24 hours. Will make that determination later this
morning once we have a clear idea of how lows this morning shakes
out.

Friday through Saturday night: That shortwave ridge of high pressure
will slide across the Inland Northwest Friday into Friday night
resulting in temperatures warming to around normal into the
weekend. A weak shortwave disturbance will push across Saturday
into Saturday night. The mountains will see up to a 30% chance for
showers. With so much dry air in place now, it will be difficult
for the atmosphere to moisten up enough for valleys to see much if
any appreciable rainfall. Best chances will be for a shower to
develop over the higher terrain and move over a valley area. I did
add sprinkles to the forecast for Saturday afternoon and evening
from the eastern Columbia Basin into the Spokane/Coeur d`Alene
area, Palouse, Lewiston-Clarkston Valley and surrounding mountain
valleys. I don`t expect much more than than with this weak
shortwave. It will increase the gap winds through the Cascades
late Saturday afternoon with the Wenatchee Area and Waterville
Plateau into the western basin expected to see wind gusts in the
range of 20-30 mph. The added cloud cover and warmer temperatures
aloft will result in more mild overnight temperatures Friday into
Saturday morning squashing any additional risk of a frost/freeze
during this period. /SVH

Sunday through Wednesday: A notable increase in moisture is expected
from late Sunday into Monday across the Inland Northwest, with
largely beneficial rain forecast for the region. This is associated
with a low pressure system that will also bring locally gusty
westerly winds, especially across the Columbia Basin. Daytime temps
look to be a handful degrees below normal for Monday and Tuesday as
well. The synoptic pattern then shifts for the mid-to-latter stages
of next week, with building high pressure becoming more likely with
much warmer temperatures and dry conditions favored. /KD

&&

.AVIATION...
06Z TAFS: Convection is winding down with the loss of daytime
heating with just a few residual showers left in north Idaho and
down around the Blue Mountains. The showers moistened the boundary
layer over N Idaho Panhandle and around Spokane Felts Field with
the relative humidity already at 85-100% at some locations. While
the models are showing very little chances for fog, current RH,
clearing skies, and light winds does support as least some patchy
fog development. Given drier air above the boundary layer with NW
winds, confidence in coverage is low, but did indicate a TEMPO
group for IFR conditions at KSFF/KCOE. Thursday will not be as
unstable, but afternoon heating will trigger scattered to broken
flat cumulus over much of Eastern Washington and North Idaho
especially over the higher terrain. Slightly greater instability
over the North Idaho Panhandle will lead to a 20 percent chance
of a shower or thunderstorm at Sandpoint between 21z Thu-02z Fri.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Convection is high for VFR conditions at KGEG/KLWS/KEAT/KMWH.
Confidence is lowest for KSFF/KCOE where a moist boundary layer
left over from recent showers could lead to fog development
overnight. Fog has the potential to impact Bonners Ferry,
Sandpoint, Coeur d`Alene, and Kellogg as well. JW

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

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        65  34  71  48  73  49 /   0   0   0   0  10  10
Coeur d`Alene  63  36  69  46  71  49 /   0   0   0   0  10  10
Pullman        60  35  68  46  70  47 /   0   0   0   0  10  10
Lewiston       70  43  77  51  79  54 /   0   0   0   0  10  10
Colville       65  32  71  41  71  42 /  10  10   0   0  20  20
Sandpoint      62  36  67  44  68  47 /  20   0   0   0  10  20
Kellogg        58  38  66  48  68  51 /  10   0   0   0  10  10
Moses Lake     71  38  76  51  79  47 /   0   0   0   0   0   0
Wenatchee      69  43  75  56  75  51 /   0   0   0   0   0   0
Omak           71  38  75  51  76  48 /   0   0   0   0   0  10

&&

.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Frost Advisory until 8 AM PDT this morning for Central Panhandle
     Mountains-Idaho Palouse-Northern Panhandle.

WA...Frost Advisory until 8 AM PDT this morning for Spokane Area-
     Upper Columbia Basin-Washington Palouse-Western Okanogan
     County.

     Freeze Warning until 8 AM PDT Friday for Northeast Mountains-
     Okanogan Highlands.

&&

$$