Marine Weather and Tide Forecast for Dover, ID

SYNOPSIS
A wet weather system will be situated over the Inland Northwest through Friday. Moderate to heavy precipitation with rain and a mix of rain and snow in the valleys. Rain over the Palouse into the southern Idaho Panhandle will lead to rises on rivers and small streams. A transition to snow for northern valleys in northeast Washington into the Northern Panhandle may lead to travel impacts in the valleys for Friday morning. Drier over the weekend and warming above normal next week.

DISCUSSION

Tonight through Saturday: A moderately strong Atmospheric River will be situated across the region through Friday. The prognoses is for the moisture plume with P-Wats up to 0.8-0.9 into the coastal areas to remain nearly stationary across southern Washington into the southern Idaho Panhandle. The plume does shift north slight through the night, but not by much.
There is high confidence for heavy precipitation in the neighborhood of 2 inches to fall from the Northeast Blue Mountains to the southern and central Idaho Panhandle. There are two primary questions introducing uncertainty into the forecast: (1) what will snow levels be at across the Palouse, and (2) how much moisture pivots north across the Spokane/Coeur d'Alene Area overnight into Friday morning? Addressing the first questions:

The latest forecast from the National Blend of Models shows snow levels over the Palouse, but with a tight gradient. The northern Palouse region around Rosalia and Tekoa is expected to see snow levels between 2,500-3,000 feet with mostly wet snow falling, and the southern portion of the Palouse around Colton and Uniontown rising to between 4,000-5,000 feet where precipitation is expected to fall as rain. Then a lot of uncertainty in between with the precipitation type potential, including Pullman- Moscow. A winter weather advisory remains in effect for the Palouse region through Friday morning east of Highway 195 for the potential of wet snow to create slippery conditions, but latest trends indicate that we may see more rain than snow. As such, we are also issuing a Flood Watch that will cover Whitman, Latah, Garfield, Asotin, Nez Perce, and Lewis counties. There is a concern for small stream flooding across this area along with a risk for rock slides.

Addressing the second question of moisture pushing north overnight and what that means for winter weather across the Spokane Area, Coeur d'Alene Area, Silver Valley and mountain valleys north of these locations. Dew point temperatures indicate a much drier air mass for these areas, and confidence is increasing that precipitation type would fall as snow. It will just be a matter of how moisture will be available for accumulating snow, as well as, how efficiently it will accumulate on roads. Slightly more northward shift of the AR and then we're looking at heavy wet snow for Friday morning that may impact the commute for the Spokane and Coeur d'Alene areas.
Confidence for impacts due to snow in the lowlands is low and will elect to forego issuing a Winter Weather Advisory right now, but it will be a situation to monitor for this evening.

This then brings us to the mountain snow potential. Heavy mountain snow will continue across the Cascades and in the Idaho Panhandle. An additional 1 to 2 feet of snow is expected over Stevens Pass through Friday before tapering off as a cold front shunts the moisture southeast. Lookout Pass is expected to receive around an additional 2 feet of snow through Saturday with the heaviest snowfall expected tonight through Friday. Snow will continue through Friday night into Saturday, but we will also see snowfall rates become less. The cold front will sweep across the rest of Eastern Washington and the Idaho Panhandle Friday night. Westerly winds will increase for Saturday with gusts generally up to around 30-40 mph across the exposed areas of the Columbia Basin. These winds will be much less than what we just experienced.

Saturday night through Thursday: A drying trend commences over the weekend. This will result in rivers and streams to subside.
Temperatures will remain below normal. This will quickly change next week with a warm front pushing across Sunday into Sunday night. Not much moisture with this front. It will bring light snow to the mountains, but more notably will be the increase in temperatures for next week as it will usher in much warm air.
Temperatures climb into the upper 60s to near 70 in the Columbia Basin by Tuesday into Wednesday. The main concern with the warmer temperatures is to monitor river levels for rises with snow melting at low to mid elevations. /SVH

AVIATION
00Z TAFS: A moisture laden frontal boundary with subtropical moisture has stalled across southern Washington into the southern and central Idaho Panhandle this evening. Persistent rain will fall at KPUW and KLWS. Ceilings will also lower at both airport terminals with MVFR conditions by this evening IFR to low IFR overnight. Preciptiation type will be tricky at KPUW with incr precip intensity lowering snow levels but trends are toward less snow and more rain at PUW. There is marginal wind shear at PUW this evening with winds 1000-2000 ft AGL around 35kts. The marginal wind shear will decrease 6-7Z. The band of precipitation will slowly meander further north overnight with wet snow or a rain/snow mix also expected at KGEG/KSFF/KCOE and IFR conditions developing. Any snow accumulation will be wet and slushy into Friday morning. GEG/COE has a 20% for 2 inches or more accum with PUW chances at 10%.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for IFR conditions to develop with precipitation tonight after 04Z at KEAT/KGEG/KSFF/KCOE/KPUW airport terminals; however, confidence remains low for precipitation type. Thermal profiles aloft will support snow, but temperatures near the surface may result in at least some melting. Confidence is lowest around EAT/MWH given persistent westerly flow in the midlevels and tendency for this flow pattern to work against low-level moistening and MVFR/IFR conditions with HRRR probs from 30-50%.
/SB

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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

Preliminary Point Temps/PoPs
Spokane 45 33 42 32 44 24 / 30 80 80 70 40 0 Coeur d'Alene 45 32 41 31 43 21 / 50 90 90 80 70 10 Pullman 45 33 37 33 41 25 / 90 100 100 100 80 20 Lewiston 52 38 47 40 48 30 / 90 100 100 100 80 10 Colville 48 29 45 26 45 22 / 30 50 50 40 30 0 Sandpoint 43 30 40 30 40 21 / 60 80 80 70 80 20 Kellogg 41 32 38 33 38 19 / 80 100 100 90 90 30 Moses Lake 51 35 49 31 49 28 / 20 60 70 50 10 0 Wenatchee 46 34 46 30 43 28 / 50 80 80 40 10 0 Omak 50 30 47 28 47 27 / 20 50 40 30 10 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Flood Watch from 11 PM PDT this evening through Saturday afternoon for Lower Garfield and Asotin Counties- Northeast Blue Mountains-Washington Palouse.
Winter Weather Advisory from 11 PM this evening to 11 AM PDT Friday for Washington Palouse.
Winter Weather Advisory until 11 AM PDT Friday for Central Chelan County.
Winter Storm Warning until 5 AM PDT Saturday for Western Chelan County.
ID...Flood Watch from 11 PM PDT this evening through Saturday afternoon for Central Panhandle Mountains-Idaho Palouse- Lewis and Southern Nez Perce Counties-Lewiston Area.
Winter Weather Advisory from 11 PM this evening to 11 AM PDT Friday for Idaho Palouse.
Winter Storm Warning until 11 AM PDT Saturday for Central Panhandle Mountains.
Winter Weather Advisory until 5 AM PDT Friday for Lewis and Southern Nez Perce Counties.