Marine Weather and Tide Forecast for Spokane Valley, WA

SYNOPSIS
Heavy mountain rain, high mountain snow, and gusty winds will continue through Wednesday evening and Wednesday night. Winds and rain will taper through the day Thursday. Friday and Saturday will bring a brief break. A weak system moves in Sunday bringing light rain the mountains. Confidence is increasing for another atmospheric river early next week but with lower snow levels.

DISCUSSION
...STRONG ATMOSPHERIC RIVER BRINGING FLOODING, ROCK/MUD SLIDES, AS WELL AS STRONG WINDS THROUGH THURSDAY MORNING...

Today through Friday: Round 2 of the Pacific northwest strong atmospheric river is well underway this afternoon.

* Rain: The Cascades have put up some impressive precipitation totals since midnight (Viewpoint Raws: Over 3", Dry Creek Raws: Over 2", Stehekin Raws: Over 2"). An additional 1 to 4 inches of rain is expected for locations west of Leavenworth/Mazama to the crest of the Cascades through tomorrow evening. In North Idaho, an additional 1-2" of rain is forecasted through tomorrow afternoon. Luckily strong shadowing is currently keeping locations east of Leavenworth dry and that will continue to be the case. The flood watch in Chelan County was upgraded to a flood warning and is in effect through Friday morning. The flood watch for Kootenai/Benewah/Shoshone Counties remain in effect until Friday morning to Friday evening as well. Lighter showery activity will continue through Thursday night to Friday night as the 150-200% of normal PWAT plume migrates north into Canada. This will give time for the river flows to decrease.

* Wind: Wind advisories and high wind warnings remain in effect until 7 AM tomorrow. Forecast looks on track still for sustained southwest winds around 25-35 mph gusting up to 45-55 mph for the Upper Columbia Basin, Palouse, and Spokane area.
There is a 10% chance for isolated pockets of gusts greater than 60 mph from highway 395 at the Adams/Franklin County line, to along I-90 from Ritzville to the West Plains, the Palouse, and wind prone locations of US-95 from Worley to Cda.
Sustained southwest 35-45 mph winds gusting up to 65 mph remains for locations between Clarkston and Dayton. With unfrozen and wet soils, wind impacts may be higher than usual.
A 16-18 mb gradient from Portland to Cut Bank MT will stay established through much of the night keeping wind gusts above 40 in the advisory area. The upper ridges of southwest Chelan County will continue to gust around 60 to 100 mph through this evening. Mission Ridge Summit NWAC sensor gusted to 107 mph at the 1PM observation. Winds will slowly decrease overnight into Thursday as the surface low in the lee of the MT rockies moves into eastern MT.

Saturday through Wednesday: Mild conditions with highs in the 40s and 50s will continue through this weekend into mid next week.
Saturday look showery in the mountains as the southern periphery of the next atmospheric river is touching the Canadian border. The cold front with this system will bring light rain to the Cascades up to 0.5" from Saturday night to Sunday night. Ensembles are hinting at another potent atmospheric river early to mid next week. Snow levels look lower for this event perhaps as low as 3000 feet near the Canadian border. It is too early to discuss expected precipitation amounts but there is a 20-50% chance of 2+" of precipitation in the Idaho Panhandle mountains and an 80% chance of 2+" of precipitation at the Cascade crest from 4 AM Monday to 4 AM Thursday. /DB



AVIATION
00Z TAFs: Ceilings have been fluctuating between VFR and IFR for the eastern third of WA and north ID including at KGEG, KSFF, and KCOE through the day with passing showers and variable cloud decks impacting TAF sites. For KGEG and KSFF, showers have moved east of the area and conditions are expected to be more consistently VFR through the night, while KCOE may continue to see MVFR conditions with showers lingering longer.
KEAT, KMWH, KPUW, and KLWS have been VFR through most of the day and will stay VFR thanks to downsloping winds drying out the boundary layer. Gusty southwest winds are expected through tomorrow morning with gusts ranging from 30-50 kts across the Basin and into the Spokane area. Winds will gradually subside into tomorrow afternoon.

.FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Confidence is high for VFR conditions for KEAT, KMWH, KPUW, and KLWS.
For KGEG, KSFF, and KCOE, confidence in the forecast is lower. Ceilings could hover around the MVFR/VFR line.

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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

HYDROLOGY
The ongoing atmospheric river event will continue to drive heavy precipitation into the high terrain through Thursday. While model guidance indicates a gradual weakening of moisture transport (IVT)
over the next 24 hours, the cumulative impacts of prolonged rainfall remain the primary concern. Observed 72-hour precipitation totals as of 2:30 PM range from 4 to 8 inches along the Cascades and east slopes, with 2 to 5.5 inches recorded across the Idaho Panhandle.
Through early Friday morning, additional QPF of 1 to 3 inches is forecast for the Cascade crest extending into central Chelan and Okanogan counties, while the higher terrain of the Idaho Panhandle can expect an additional 0.50 to 2 inches.

The combination of heavy rainfall, mid-elevation snowmelt, and saturated antecedent soil conditions continue to bring heightened concerns for rock and mudslides. Areas of steep terrain and recent burn scars in both the Cascades and central Idaho Panhandle are particularly susceptible to rock and mudslides. Reports of rock and mud on roadways have already been received in these throughout Chelan County.

River Forecasts

Central Washington: The Wenatchee and Stehekin Rivers are projected to crest within flood stage between this evening (Wednesday) and early Thursday morning. Beyond the mainstem river forecast points, rapid rises are occurring on smaller rivers and creeks, specifically Icicle Creek near Leavenworth and Peshastin Creek.

Idaho Panhandle: The Coeur d’Alene River at Cataldo is forecast to reach Minor Flood Stage by Thursday afternoon. Smaller creeks and streams across the region will remain elevated with high flows.

For the latest hydrographs and specific river stage forecasts, please refer to water.noaa.gov/wfo/otx.

Preliminary Point Temps/PoPs
Spokane 48 53 41 50 40 52 / 20 20 30 20 10 10 Coeur d'Alene 48 51 41 49 41 51 / 70 60 50 40 30 10 Pullman 48 52 45 52 41 52 / 10 60 50 20 20 10 Lewiston 53 58 49 59 43 55 / 10 20 40 10 10 0 Colville 39 48 31 43 32 44 / 30 10 10 30 20 10 Sandpoint 44 49 37 44 39 47 / 90 80 40 60 50 30 Kellogg 46 49 42 49 41 52 / 90 90 70 70 40 20 Moses Lake 48 56 39 54 37 51 / 10 10 10 0 10 0 Wenatchee 46 52 42 54 40 52 / 30 10 20 10 10 0 Omak 40 48 34 44 35 44 / 10 10 10 10 10 10

OTX WATCHES/WARNINGS/ADVISORIES
WA...Wind Advisory until 7 AM PST Thursday for Spokane Area-Upper Columbia Basin-Washington Palouse.
High Wind Warning until 7 AM PST Thursday for Lower Garfield and Asotin Counties.
ID...Flood Watch through Friday afternoon for Central Panhandle Mountains-Coeur d'Alene Area-Idaho Palouse-Northern Panhandle.
Wind Advisory until 7 AM PST Thursday for Coeur d'Alene Area- Idaho Palouse.