Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
936 FXUS66 KOTX 221154 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 454 AM PDT Wed May 22 2024 .SYNOPSIS... A wet low pressure system will bring steady rain across the region through Wednesday. Snow levels will drop down to pass level with wet snow accumulations for travel over the Cascade crest. Another weather system will move in on Friday and Saturday bringing more unsettled weather into the Memorial Day weekend. Monday will be the warmest day of the holiday weekend. && .DISCUSSION... Today: Satellite shows the low moving through southern Vancouver Island early this morning. It will track to the southeast into south central WA later this morning. As it does, precipitation will wrap around the low and will keep rain and high mountain snow occurring across much of the region. Temperatures and cameras still show precip type as rain over the passes, but temperatures will lower further, and rain/snow mix or slushy snow could accumulate at the passes. Probability of an inch today for the passes are: Washington Pass 60%; Stevens Pass 20%; Sherman Pass 30%. There is a 20% chance of afternoon thunderstorms across northern WA/ID and across the Blue Mtns and Camas Prairie. Today will be the coolest day of the week with temps in the 50s, which is 10-15 degrees below average. Precip chances continue through the evening, especially for northern WA and the ID Panhandle. As the low slips into southeastern Idaho overnight, our chances of precipitation decreases except for the central and southern ID Panhandle. Slushy wet snow accumulation is possible over Lookout Pass. Thursday: We are between systems under northerly flow aloft as the next trough begins to move toward the BC coast. Some partially clearing skies Thursday morning and abundant low level moisture from the rain will aid in afternoon instability and a 20-30% chance of thunderstorms across northern WA and ID. Temperatures rebound 5-10 degrees into the 60s top low 70s, which is still a couple degrees below average. The 20-30% chance of thunderstorms continues through the evening hours, with showers confined to the north ID Panhandle overnight. Rivers will continue to fill from the rains, but none are expected to flood as we have been so dry, and these rains are proving very beneficial to our region. /Nisbet Friday through Wednesday: An upper level trough will continue through the weekend. It will keep the cool, wet pattern through the weekend. A Low will push through the region late Friday through early Sunday. It will not have as moisture as the previous system but still expected to bring amounts of 0.1-0.25". The band of highest precip will be along North Washington and the the Idaho Panhandle. With snow levels hovering around 4500ft in the Cascades, light snow could bring minor impacts to travel over the Passes. Little to no snow accumulation is expected. The Lower Central Basin is expected to be the driest with little to no precip. By Sunday, the shower potential decreases as a shallow ridge begins to cut off the moisture plume. Highs will be in the 60s and low 70s. Overnight lows will be in the upper 30s and 40s. By Memorial Day, a trend warming trend will begin. Any shower activity will be confined to the mountains. It will continue through Tuesday. Highs will reach into the 70s and low 80s. Overnight lows will be in the upper 40s and 50s. It will be short lived as ensembles are showing a strong Gulf of Alaska low bringing another fetch of moisture into the region late Tuesday and Wednesday. The Inland Northwest will see another round of widespread showers. /JDC && .AVIATION... 12Z TAFS: A weather system will bring MVFR/IFR conditions with rain over the east third of WA and ID, including GEG/SFF/COE/PUW/LWS. Some patchy fog/mist is possible thru the early morning too. The precipitation wanes briefly around TAF sites in the morning, but increase in the afternoon through evening at all TAF sites as the low tracks just south of the area, before starting to pull away later Wednesday evening. There will be a small risk for t-storms in the afternoon across northern WA/ID not impacting TAF locations, but around Republic, CQV, Bonners Ferry, and down across the Blue Mtns and Camas Prairie of ID. After sunset cigs for GEG/SFF/COE/PUW will lower down to MVFR conditions. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate to high confidence in ceiling improving throughout the day and then lowering again overnight. ----------------------- 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 57 40 64 45 67 45 / 80 20 30 10 10 40 Coeur d`Alene 53 40 60 45 65 45 / 90 30 40 20 20 50 Pullman 52 38 59 40 64 43 / 80 10 10 0 10 40 Lewiston 60 45 66 46 73 50 / 70 20 10 0 10 40 Colville 54 35 64 39 65 40 / 90 30 70 60 50 50 Sandpoint 50 38 58 44 62 44 / 100 60 60 50 50 60 Kellogg 50 42 57 45 62 46 / 100 60 40 20 40 60 Moses Lake 61 43 72 44 73 44 / 30 10 0 0 10 10 Wenatchee 59 47 71 47 70 47 / 20 10 0 0 10 10 Omak 60 43 72 45 70 45 / 70 20 30 10 20 30 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$