Marine Weather and Tide Forecast for Clark Fork, ID

SYNOPSIS
An incoming weather system Friday will bring chances for rain and light mountain snow as well as cooler temperatures and gusty winds. Blowing dust will also be possible Friday and Sunday.
Colder air comes in this weekend and early next week, with many areas seeing freezing temperatures at night. Drier weather next week.

DISCUSSION
This evening and tonight: Weather will be relatively quiet for one a little longer, as high pressure begins to yield to a strong system approaching from the west. Sunshine has been filtered through high clouds today. Those clouds will begin to thicken from the west, especially over the Cascades and northern mountains, later tonight into early Friday. The first shower chances begin to touch the Cascade crest overnight, but it will remain dry. Lows tonight will be mostly in the 40s, with lower 50s near the Wenatchee Area and L-C Valley.

Friday to Sunday: A strong mostly dry cold front pushes across the region Friday, while an upper trough dives in behind it Friday night into Saturday, before it gradually moves out Sunday. The front Friday will bring rain to the Cascades in the morning, especially near the crest. By late morning to afternoon chances expand toward the eastern third of WA and ID, while the PoPs in the Cascades start to decrease. By Friday evening the precipitation chances continue over the ID Panhandle and near the Cascade crest, but will be waning over the eastern third of WA so that by overnight the main risk is at the Cascade crest and near the Canadian border and near the Camas Prairie and Clearwaters. Then as the trough axis start to migrate across the region from northwest to southeast the precipitation chances redevelop over the near the Cascades through northeast WA and north ID Saturday afternoon and into central WA and the central ID Panhandle in the evening, before chances start peter out overnight into Sunday. Overall precipitation amounts are most centered around the mountains and very light outside of the mountains, so the majority of the CWA the front will pass with mostly dry. We will watch for some fog Saturday morning, after precipitation and when winds decline. The best potential is over the sheltered valleys of northeast WA and north ID.

Snow levels start near 7-9kft Friday morning, then drop to 5-8kft by evening with strong CAA with the cold front, then between 4-5.5kft by Saturday morning then moderate slightly in the afternoon and evening, lowest near the Cascades. This is the main period where precipitation will fall, so snow is found in some of the mountain areas in between late Friday night into Saturday. The best chance for accumulating snow is around the Cascades crest, but other snow could also be found near places like Sherman Pass and Lookout pass. Accumulations look rather light in most areas. The main areas that could see a bit more is the higher back-country mountain near the Cascades, so those hiking or camping there will see to monitor things and take precautions for snow and colder weather.

Winds will be the more widespread impact between Friday to Sunday. Winds start to increase Friday morning, then peak in the afternoon to early evening. Winds will be out of the southwest, turning west in the afternoon, at 15-25 mph with gusts of 30-40 mph possible over the Columbia Basin eastward. Localized gusts of 50 mph are possible, but confidence is low with probabilities only near 10-15% per the NBM. I did increase winds above the NBM for the winds over the Palouse, which seems to under-do things. Winds start to wane Friday night, but starts to turn northerly over the Okanogan Valley from late evening to overnight into Saturday and increase to 10-20 mph with gusts to 30 mph. By late Saturday afternoon winds throughout the remainder of the CWA sees winds turning north to northeast and increase in late evening to overnight. Winds remain strong through Sunday out of the northeast. Winds Sunday are forecast to be similar to the strength as Friday, but out of the northeast; but it will come with the addition of the ID in that stronger wind potential.

Blowing dust is in the forecast Friday and again Sunday. Friday has the broadest blowing dust potential with winds out of the southwest to west. Most areas from the Waterville Plateau to WA/ID border have the potential, but strongest winds are Waterville Plateau to Upper Columbia Basin. Blowing dust advisories are in place from noon to 7 PM Friday for the potential for visibilities down to 1 mile or less. Not a lot of rain has fallen and not a lot is expected; last week there was some blowing dust that caused of impacts over the Upper Columbia basin and not much has changed. Blowing dust is also possible again Sunday. So we will monitor potential impacts then too.

Temperatures will be trending down over next several days.
Highs Friday will be in the 60s to mid-70s, then 50s to low 60s this weekend and some upper 30s and 40s in the mountains. Lows will in the 30s and 40s, with some 20s Saturday and Sunday night (into Monday morning). Many areas could see freezing temperatures this weekend, especially Sunday night/Monday AM.

Monday to Thursday: Going into the new work week models continue to show a fair amount of disagreement. Subtle ridging develops early in the week, then another trough tries to move into Tuesday night but how it evolves after that has low confidence.
Some indicate a deeper trough that lingers and other a weaker more transient trough that is followed by some ridging. The forecast goes with the more progressive weaker trough.
Precipitation chances come back in Tuesday into early Wednesday, then wane into the end of the week. But we will have to keep an eye on this. Highs will be in the 50s to lower 60s, with lows in the 30s to low 40s except for some upper 20s in the sheltered northeast valleys. /Solveig



AVIATION
18Z TAFS: Dry at lower levels of the atmosphere will promote VFR conditions. Winds will be light and less than 10 kts, and generally be diurnally driven today and tonight. A strong cold front is expected tomorrow (Friday). The front will bring gusty west winds with the potential for blowing dust in the afternoon across the Columbia Basin. There is a small chance (20%) of -RA for KCOE between 18-00z tomorrow with the cold front.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions at airport terminals.

-----------------------

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 48 67 39 56 37 53 / 0 20 0 0 10 0 Coeur d'Alene 47 66 39 55 36 52 / 0 30 10 0 10 0 Pullman 47 66 36 53 33 53 / 0 20 20 0 20 10 Lewiston 51 75 44 59 40 57 / 0 0 20 0 20 20 Colville 41 66 31 55 27 56 / 0 20 10 50 30 0 Sandpoint 44 63 34 52 29 49 / 0 40 20 20 10 0 Kellogg 48 65 37 52 32 47 / 0 30 50 10 20 0 Moses Lake 47 70 37 60 37 59 / 0 10 0 0 10 0 Wenatchee 55 67 45 59 44 59 / 0 10 0 30 60 0 Omak 50 69 37 57 36 59 / 0 10 0 40 50 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Blowing Dust Advisory from noon to 7 PM PDT Friday for Spokane Area-Upper Columbia Basin-Washington Palouse-Waterville Plateau.
ID...None.