Marine Weather and Tide Forecast for Leavenworth, WA

SYNOPSIS
Dry, warm conditions through Monday. Unsettled weather returns Tuesday into Wednesday next week, with potential for some moderate rains.

DISCUSSION
Today through Tuesday morning: A ridge centered over the state of Washington will result in mostly dry and warming conditions with little to no impacts through early Tuesday morning. High temperatures will rise into the mid 70s with some isolated low 80s by Monday. Low temperatures will rise into the high 40s by Monday night.

Tuesday through Thursday: Chances for precipitation increase as a low pressure system nears the PNW coast and moves inland over the California/Oregon border. By midday Tuesday, PoPs will have increased across the forecast area. As the low pressure system moves further inland and to the northeast, heights will lower across the eastern third of Washington and the Idaho Panhandle through Wednesday. Paired with a surface low resulting in a frontal passage, much of the heavier precipitation associated with the low will be confined to this area, though the majority of the forecast area will see at least a wetting rain (0.10 inches) by Wednesday evening.
Wednesday morning through Thursday morning, much of the Idaho Panhandle and southeast Washington see 0.5 inches of rain. Isolated higher rainfall totals nearing 0.75 inches of rain are possible in the WA/ID Palouse and in the foothills of the Central ID Panhandle.
This will lead to rises on rivers and streams, and possible nuisance flooding in poor drainage areas. In particular, Kootenai River at Bonners Ferry is forecast to go into Action Stage by early Thursday morning. Stehekin River is seeing ongoing hydrologic issues, and is expected to reach Minor Flood Stage by Monday.

Aside from the rain, there are a few other characteristics of this weather pattern that will result in impacts across the area. Snow levels with this system will be very high, starting at 8000 feet and lowering to 4500-5000 feet by Thursday. Much of this snow will be above pass level. Lookout Pass does have a chance of an inch or so of snow through Wednesday through Thursday. Bottom line: expect little to no wintry travel impacts along mountain passes. Chances for thunderstorms increase, particularly on Tuesday as temperatures will still be warm ahead of the incoming frontal passage. CAPE values are modest on Tuesday night, with 300-500 J/kg expected through Tuesday evening. Main risks with these thunderstorms will be gusty outflow winds and small hail. With the frontal passage, winds will increase Wednesday afternoon, especially across the Cascades, Okanogan Valley and Highlands, Waterville Plateau, Moses Lake, Basin, and northern Blues areas, with gusts 20-25 mph expected and locally higher wind gusts near 35-40 mph. Additionally, high temperatures will drop considerably, nearly 15-20 degrees, from Tuesday to Wednesday. Low temperatures will not see quite as dramatic a drop, though it will still be noticeable at 10-15 degrees.

Friday through Sunday: By Friday, the low pressure system will have moved out of the area and heights will have increased due to a ridge off the coast of Canada. This is where clusters and long term models diverge. There is little agreement in how far the higher heights move inland. However, even with this disagreement, there will overall be a warming and drying trend through next weekend with the departure of the low. /AS

AVIATION
06Z TAFS: VFR conditions with mostly light and variable winds will prevail through the forecast period. High cloud decks will mostly be few or scattered through 18-20Z, when a more broken deck will settle in as upper level moisture increases. PUW will see 10-12kt winds through this morning, but those winds will decrease around 00Z.

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

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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 70 44 75 48 76 48 / 0 0 0 0 0 40 Coeur d'Alene 70 44 75 48 76 48 / 0 0 0 0 0 50 Pullman 67 45 75 48 72 46 / 0 0 0 0 10 60 Lewiston 73 47 79 51 76 51 / 0 0 0 0 10 60 Colville 71 41 78 45 80 48 / 0 0 0 0 10 40 Sandpoint 67 43 72 46 75 48 / 0 0 0 0 10 50 Kellogg 68 46 75 49 77 48 / 0 0 0 0 10 50 Moses Lake 76 46 81 49 79 52 / 0 0 0 0 10 40 Wenatchee 72 50 77 54 77 55 / 0 0 0 0 10 30 Omak 72 46 79 51 79 53 / 0 0 0 0 10 20

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