Marine Weather and Tide Forecast for Dover, ID

DISCUSSION

...COLDEST TEMPERATURES OF THE SEASON WITH NEAR TO BELOW ZERO TEMPERATURES POSSIBLE EARLY NEXT WEEK...

Today through Sunday Night: Ahead of the next shortwave that will slide through the region, snow flurries have formed around eastern WA and the ID Panhandle overnight due to the low stratus. Light accumulations are expected with these before the heavier snow moves in this afternoon. Low stratus will continue through the day. A northwesterly flow will bring a fresh round of snow, with the heaviest accumulations in southeast WA and the central/southern ID Panhandle. A Winter Weather Advisory remains in effect for these ares. Snowfall could be intense due to the cold temperatures aloft, leaving snow ratios to be in the 15:1 to 20:1 ratio. Winds will be a bit breezy, with gusts of 15 to 20 mph that could cause blowing snow around the Palouse. Snow will vary significantly around the Spokane area depending on the track of the shortwave. Any slight shift could leave Spokane either more or less than forecasted. Sunday will be quieter for much of the region with light snow showers expected over southeastern WA and southern ID Panhandle ahead of the arctic air that will bring the coldest temperatures of the season.

Highs will remain in the 20s and 30s, still below normal, with overnight lows in the 20s for the LC Valley and single digits in the northern Mountains. /KK

Monday through Wednesday night: The beginning of next week will be dry and COLD!!! Expect our coldest temperatures with a late season cold snap. A weak Arctic boundary will push down out of Canada on Monday and this will deliver widespread single digit temperatures to below zero temperatures across the region Tuesday morning and again Tuesday night into Wednesday morning. North to northeast winds will also increase Monday morning down the Okanogan Valley and Purcell Trench that will then fan out across the Columbia Basin. The 1 1/3 km resolution WRF model out of the University of Washington is just now able to go out through Monday morning, and it is indicating the potential for wind gusts up to around 40 mph down the Okanogan Valley. This model tends to capture the relatively smaller scale features of winds squeezing down the Okanogan Valley than say the global models further out in the extended. Winds up to 40 mph may be a bit overzealous, but I do think that wind gusts of 30-35 mph are definitely within the realm of possibility. Similar wind speeds can be expected on the Waterville Plateau, and could see gusts of 25-30 mph down the Purcell Trench into the Coeur d'Alene Area on Monday. Winds look to relax overnight Monday into Tuesday, but will remain a little breezy. The combination of breezy winds and cold modified Arctic air will result in bitterly cold wind chill values of -5 to -15 degrees across much of the region, especially the northern half. Temperatures this cold will increase the potential for frostbite and hypothermia if not dressed appropriately for the outdoor conditions. Tuesday night will be another cold night and could result in colder ambient temperatures as there is expected to be less in the way of wind to keep the boundary layer mixed. Tuesday and Wednesday mornings look to be the coldest days over the next week.

Thursday through Saturday: There is uncertainty in the model ensembles with how much southerly flow we will be able to introduce into the region late next week. A shortwave trough of lower pressure will move in off of the eastern Pacific, but model solutions vary with how far north to transport this moisture up into the Northwest Region. The uncertainty in the extended model guidance is resulting in a wide range of temperatures and snow potential.
As an example, the ECMWF Ensemble shows Pullman picking up to 6 inches of snow over a 24 hour period on Friday, but this is from fringe model members that indicate moisture on the higher end of the envelope. The low temperature in Spokane varies from 11 to 23 degrees between the 25th percentile and 75th percentile off of the National Blend of Models. The colder low temperature potential for Friday represents a drier scenario with less in the way of moisture/cloud cover, whereas the more mild low temperature of 23 degrees represents a better potential for moisture, cloud cover, and snow. Needless to say, details for later next week still need time to be figured out, but there continues to be the potential for wintry weather and associated impacts. /SVH

AVIATION
18Z TAFS: Low stratus continues across KGEG-KSFF-KCOE-KPUW-KMWH with light snow. Stronger snow showers will develop around 20z in the KGEG-KSFF-KCOE-KPUW vicinity capable of producing IFR visibility restrictions. The higher confidence of the heavier snow showers is over the Palouse and PUW. Brief reductions to LIFR in the heavier bands is possible. Showers will generally exit the GEG/SFF/COE area to the south and east aft 00Z. The showers will continue through 03-06Z for the southeast corner of WA and the southern ID Panhandle including PUW/LWS.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: The main activity will end by 06Z, but cannot rule out some additional -sn through the night for PUW/LWS. Cigs will improve for MWH/EAT through the night, with skies partially or completely clearing towards sunrise. Alternate scenario is fog developing at any taf location towards sunrise, tho confidence is low. Many models suggest drier air moving in from the north through the period, but given the snow expected through the day, the boundary layer may remain saturated enough for fog development, especially if there is a brief break in the clouds.

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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

PRELIMINARY POINT TEMPS/POPS
Spokane 30 12 27 8 24 1 / 60 30 10 10 10 0 Coeur d'Alene 29 14 28 8 25 0 / 70 40 10 10 10 0 Pullman 29 20 28 12 24 2 / 70 80 20 20 20 10 Lewiston 34 24 33 18 29 7 / 30 80 20 10 10 10 Colville 29 5 27 3 25 -2 / 30 20 10 10 0 0 Sandpoint 28 14 27 10 23 4 / 70 20 0 10 10 0 Kellogg 29 17 27 8 22 2 / 80 70 10 10 20 10 Moses Lake 32 14 32 13 29 8 / 20 10 0 10 10 0 Wenatchee 29 15 30 15 25 8 / 20 10 0 10 10 10 Omak 28 9 27 8 26 4 / 20 20 10 0 0 0

OTX WATCHES/WARNINGS/ADVISORIES
ID...Winter Weather Advisory from 1 PM this afternoon to 4 AM PST Sunday for Central Panhandle Mountains-Idaho Palouse-Lewis and Southern Nez Perce Counties-Lewiston Area.

WA...Winter Weather Advisory from 1 PM this afternoon to 4 AM PST Sunday for Washington Palouse.