303
FXUS66 KOTX 301203
AFDOTX

Area Forecast Discussion
National Weather Service Spokane WA
503 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...
12Z TAFS: The fog band on this morning satellite loop reveals fog
expanding in the mountain valleys of northeast Washington and the
Idaho Panhandle. Airports that may see patchy fog and a range of
low IFR to MVFR conditions through 15Z include KSFF-KCOE-KDEW-
KSZT-K65S. Fog will quickly burn off by 15Z with cumulus build ups
forming over the higher terrain of northeast Washington into the
Idaho Panhandle. Isolated to scattered showers are expected with
cumulus clouds over the Panhandle this afternoon, especially near
the Sandpoint and Bonners Ferry airports. Few to scattered fair
weather cumulus is expected across KGEG-KSFF-KCOE corridor and on
the Palouse (KPUW) and Lewiston-Clarkston Valley (KLWS). Expect
VFR conditions and westerly winds of 8-12 kts this afternoon.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS:
Confidence is high for VFR conditions at KGEG-KLWS-KEAT-KMWH-
KPUW. Confidence is lowest for KSFF and KCOE where a moist
boundary layer left over from recent showers could lead to fog
development through 15Z. There is a 10% chance for fog and brief
IFR conditions at KSFF and less than 5% chance at KCOE. /SVH

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

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.

&&

$$