NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION. Privacy and Cookie policy

FXUS66 KOTX 052305 AFDOTX

Area Forecast Discussion National Weather Service Spokane WA 305 PM PST Tue Dec 5 2023

SYNOPSIS
Mild and wet weather will be in place through Wednesday with a significant snow melt expected in the valleys and potential for minor flooding issues. Cooler temperatures return Thursday into next weekend with several opportunities for snow.

DISCUSSION

...MILD WITH PERIODS OF MODERATE TO HEAVY RAINFALL FOR AREAS OF THE INLAND NORTHWEST THROUGH WEDNESDAY...

Tonight through Wednesday Night: An atmospheric river remains aimed at the region with subtropical moisture aimed at the Inland NW ahead of an upper trough. The highest precipitable water anomalies will persist over NE Washington into the North Idaho Panhandle tonight into Wednesday with values 200-300% of normal...or in the 95th to 99th percentile for this time of year.
In addition 850mb winds out of the southwest at 20-30 kts will provide added upslope flow into the rising terrain of NE Washington into the ID Panhandle. An additional 1-2 inches of rain is forecast in the valleys of Stevens, Pend Oreille, Boundery, Bonner, Shoshone, and portions of Kootenai county which has been placed in a flood advisory. The mountains will see heavier amounts with an additional 2-4" of rain. Chelan county has also been included in the advisory where 2-3 inches of rain has already fallen in the western part of the county. Rain and melting snow will lead to sharp rises on small streams, with field flooding and flooding in poor drainage areas. Snow levels will be very high between 7000-8000 feet which will add to runoff into area rivers and streams. The air mass will remain very mild over the region into Wednesday, with overnight lows tonight in the 40s for the Columbia Basin, Palouse, LC Valley, and up into the North Idaho Panhandle. A few of the northern mountain valleys and the East Slopes where the colder air has been slow to moderate will see lows in the mid to upper 30s such as Winthrop, Wenatchee, and Colville.

A cold front moving into the Cascades Wednesday morning will move into Central WA Wednesday afternoon and then Eastern WA/N Idaho in the late afternoon and evening. This will keep steady precipitation going, but also dropping snow levels from west to east. But with the bulk of the precipitation falling ahead of the cold front snow amounts are expected to be light in the mountains. Snow levels drop to 2500-4000 feet behind the front with up to 1" forecast for the Cascade crest and ID Panhandle. This should aid in reducing runoff from mountain snow melt in the Cascades by early Wednesday evening, and over NE Washington and North Idaho by early Thursday morning. JW

AVIATION
00Z TAFs: An axis of subtropical moisture draped across the Inland Northwest will result in persistent rain for North Idaho and Eastern WA. Pullman and Lewiston will be south of the main precipitation axis and have the greatest probabilities for several hours of dry conditions and VFR skies. South and southeast boundary layer winds into Moses Lake, Spokane area, and Coeur d'Alene makes for a tricky ceiling forecast as some of this drier air penetrates north with a mix of VFR/MVFR conditions expected.
For the East Slopes of the Cascades into the northern mountain valleys, persistent low clouds producing IFR to MVFR conditions are likely as rain continues to feed into an already saturated boundary layer.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS: Confidence is low/moderate at KMWH/KGEG/KSFF/KCOE with precise CIGS and visibilities as this area is near the boundary of a saturated boundary layer, with some drying in the boundary layer from south- southeast boundary layer winds over the palouse area moving north- northwest. Confidence is moderate/high for IFR/MVFR conditions along the East Slopes of the Cascades and northern mountain valleys. Confidence is moderate/high for VFR conditions through the TAF period at KPUW/KLWS. 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 46 49 33 40 29 36 / 100 80 100 70 50 20 Coeur d'Alene 45 49 36 40 30 35 / 100 70 100 80 60 40 Pullman 43 51 36 42 30 36 / 50 40 100 80 70 40 Lewiston 47 57 41 48 35 42 / 10 30 90 50 60 30 Colville 35 43 30 37 25 36 / 90 90 90 70 50 20 Sandpoint 43 44 36 38 30 35 / 100 100 100 90 80 60 Kellogg 41 47 35 38 32 33 / 90 50 100 100 80 80 Moses Lake 42 49 34 45 29 42 / 90 90 70 20 10 0 Wenatchee 36 42 33 42 31 40 / 40 80 50 30 20 0 Omak 39 43 30 40 29 38 / 60 80 60 30 20 0

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

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Spokane, WA,