Marine Weather and Tide Forecast for Leavenworth, WA

SYNOPSIS
Dry, warm conditions through Tuesday. Unsettled weather returns Tuesday afternoon into Wednesday next week with potential for moderate rains, thunderstorms, and gusty winds.

DISCUSSION
Sunday afternoon through Tuesday morning: A ridge of high pressure remains over the Western US, keeping conditions dry and warm through Tuesday morning. Passing high clouds will lead to filtered sunshine. Afternoon high temperatures peak in the 70s to low 80s Monday and Tuesday. Overnight lows will range from the 40s to low 50s.

Tuesday afternoon through Wednesday: Chances for precipitation start to move over the Cascade crest Tuesday morning as the closed low off the northern CA coast tracks inland. By late Tuesday afternoon, precip chances will spread east across the northern mountains, southeast WA, and ID panhandle. PoPs become focused over the eastern third of WA and the ID Panhandle Tuesday night into Wednesday. Very wet conditions are in store for these areas with PoPs ranging from 70-90 percent Tuesday night through Wednesday night. Snow levels will start out around 8000 feet Tuesday afternoon and will fall to around 5000 feet by Wednesday night. Expect precip to be in the form of rain and high mountain snow.

The bulk of the rain is expected to fall overnight Tuesday into Wednesday as a deformation axis sets up over the region. The highest precip amounts are forecast across southeast WA and the central ID Panhandle. The NBM 50th percentile has 0.7 to 0.9 inches of rain in the forecast over this time period for locations including Pullman, Lewiston, Kellogg, Orofino, and Saint Maries. Amounts generally decrease to the northwest, with 0.2 to 0.4 inches of rain in the forecast for Ritzville, Davenport, Spokane, and Bonners Ferry. For locations like Omak, Twisp, Wenatchee, and Coulee City, less than 0.1 inches of rain is forecast. It is worth noting that ensembles are still depicting a large range of possible precip amounts, indicating significant uncertainty as to how this event will play out and where exactly that deformation band will set up. The spread between the NBM 10th percentile (low end) and NBM 90th percentile (high end) QPF forecasts is over an inch for much of southeast WA and the ID Panhandle. Even the 25th-75th percentile spread is over half an inch for most locations.

In addition to precip chances, the track of the low will result in upper level diffluence and instability across the Inland Northwest, bringing potential for thunderstorms Tuesday afternoon and evening. Highest thunderstorm chances (20 to 30 percent) will be across southeast WA and the central ID panhandle with lower chances (15 to 20 percent) across the Cascades, northern mountains, northern ID panhandle, and eastern third of WA. The main risks with storms that develop will be gusty winds and pea sized hail.

As for temperatures, Wednesday onward will be around 15 degrees cooler than Monday and Tuesday. Afternoon highs will be in the mid 50s to upper 60s (coolest over the ID Panhandle, warmest over the western Columbia Basin and Okanogan Valley). With the cooling temperatures, expect breezy winds with gusts 20 to 30 mph Tuesday night into Wednesday.

Thursday through Saturday: Temperatures remain constant in the 50s and 60s, but precip potential wanes across the region.
/Fewkes

AVIATION
00Z TAFS: An upper-level ridge is currently over the Inland Northwest with a deep upper-level closed low offshore. VFR conditions will continue with passing mid and high level clouds through the period. Winds will generally be light, less than 10 kts.

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 44 75 48 75 46 54 / 0 0 0 10 50 80 Coeur d'Alene 44 75 48 75 46 54 / 0 0 0 10 60 90 Pullman 45 74 48 70 43 49 / 0 0 0 10 70 90 Lewiston 47 78 51 75 49 54 / 0 0 0 10 70 90 Colville 41 78 45 80 47 66 / 0 0 0 10 40 60 Sandpoint 45 70 47 72 44 54 / 0 0 0 10 50 90 Kellogg 46 74 50 76 46 51 / 0 0 0 10 60 90 Moses Lake 45 81 49 77 49 68 / 0 0 0 10 40 50 Wenatchee 50 78 53 76 53 66 / 0 0 0 10 30 30 Omak 47 74 50 74 50 69 / 0 0 0 10 20 30

OTX WATCHES/WARNINGS/ADVISORIES
WA...Flood Watch from late tonight through Monday afternoon for Western Chelan County-Western Okanogan County.
ID...None.