Marine Weather and Tide Forecast for Manson, WA

SYNOPSIS
A broad ridge remains over the Central US, driving a warming trend across the Inland Northwest through Wednesday. Hot and unstable conditions, low humidity, lightning potential, and periodic gusty winds will maintain elevated to critical fire weather conditions across portions of Central and Eastern Washington through at least Thursday. Hot and dry weather returns early next week.

DISCUSSION
Wednesday: The Inland Northwest remains under southwest flow aloft with an area of low pressure spinning off the Washington/Oregon coast and a broad ridge of high pressure over the Central US. An influx of monsoonal moisture will persist through the day on Wednesday, bringing a 15-30% chance of showers and thunderstorms over the Cascades and northern mountains Wednesday afternoon and evening. The sub-cloud layer will be rather dry, so initial showers will likely be light in intensity (or may just fall as virga, evaporating entirely before they reach the ground). Some early morning cloud cover is forecast to clear by late morning into early afternoon. If clouds can clear out quickly over lowland areas, this will allow temperatures to warm into the mid to upper 90s for most locations with potential for a few triple-digit readings. The latest NBM gives Moses Lake a 10% chance of hitting 100 degrees, Omak a 20% chance, and Lewiston a 35% chance. Late morning clearing and subsequent surface heating would also increase chances for convective showers and thunderstorms by afternoon and evening. The Storm Prediction Center has placed the Cascades and northern mountains under an area of Isolated Dry Thunderstorm Risk given the dry sub-cloud layer.

Thursday: Recent model runs have maintained good agreement on the evolution of the low pressure system off the coast heading into Thursday. The upper-level low will meander toward Central Oregon Wednesday night into Thursday, placing the Inland Northwest in a region of diffluence. The resulting lift combined with monsoonal moisture in place will be favorable for thunderstorms starting overnight Wednesday and lasting through the day on Thursday. Compared to Wednesday, the dynamics and thermodynamics on Thursday look more conducive to the formation of stronger thunderstorms. Profiles look fairly impressive for hail with the bulk of the instability concentrated above the freezing level and moderately steep lapse rates in the 700-500 mb layer between 7.5-8.5 C/km. Shear profiles also look favorable for stronger cells with 35-50 kts of bulk shear across the region. Deep inverted-V soundings are concerning for strong outflow gusts with any storms that develop. Best chances for thunderstorms look to be overnight Wednesday into early Thursday over the Cascades, western Columbia Basin, and north- central mountains, but there is at least a 10% chance of thunderstorms regionwide. The Storm Prediction Center has nearly all of Eastern Washington and portions of North Idaho under an Isolated Dry Thunderstorm Risk for Thursday. In addition, Fire Weather Watches have been issued for the Cascades, Waterville Plateau, western Columbia Basin, and northern mountains Wednesday night into Thursday for dry lightning.

Friday through Monday: By Friday, the upper-level low will migrate toward Vancouver Island, keeping the main thunderstorm risk limited to far northeastern Washington and North Idaho.
Forecast confidence increases for hot and dry weather returning over the weekend into early next week as the trough departs the region and ridging nudges back in over the Inland Northwest.
Temperatures over the weekend will range throughout the 90s. By Monday and Tuesday next week, temperatures will further warm into the mid 90s to low triple digits. /Fewkes

AVIATION
12Z TAFS: High confidence for VFR conditions across Eastern WA and North Idaho. High clouds are moving into the region this morning and will decrease 16-20z. There is a 10-20% chance of showers and thunderstorms developing over the higher terrain of the Cascades and mountains along the Canadian border. Greatest risk will be between 20-03z. Confidence on a shower or storm impacting terminals is low. Will need to closely monitor trends around Wenatchee, Chelan, Winthrop, Colville, and Republic.

FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: High confidence for VFR conditions for the area. Confidence is low on showers or thunderstorms impacting any terminals and greatest risk thunderstorms is focused along the Canadian border per the latest HRRR thunderstorm probabilities. There are a few hi-res models that do indicate a few cells developing over the Waterville Plateau between Wenatchee and Chelan Wednesday afternoon/evening which will need to monitored closely for thunderstorms in close proximity of Omak, Chelan, and Wenatchee.
/sb ----------------------- 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 95 61 99 63 91 59 / 0 0 10 20 10 0 Coeur d'Alene 95 63 99 64 90 60 / 0 0 10 20 10 0 Pullman 92 56 94 55 85 53 / 0 0 0 20 0 0 Lewiston 99 66 101 66 94 63 / 0 0 10 20 0 10 Colville 95 57 98 59 92 55 / 0 10 10 50 10 0 Sandpoint 93 66 97 62 91 60 / 0 0 10 30 10 0 Kellogg 90 59 96 61 88 58 / 0 0 10 30 10 10 Moses Lake 98 66 98 61 92 58 / 0 20 20 10 0 0 Wenatchee 98 73 96 66 91 64 / 0 50 30 10 0 0 Omak 99 69 98 65 94 60 / 10 10 20 40 10 0

OTX WATCHES/WARNINGS/ADVISORIES
WA...Fire Weather Watch from late tonight through Thursday morning for East Washington Central Cascades (Zone 696)-Foothills of Central Washington Cascades (Zone 705)-Waterville Plateau (Zone 706)-Western Columbia Basin (Zone 707).
Fire Weather Watch from late tonight through Thursday evening for Colville Reservation (Zone 702)-East Portion of North Cascades National Park/Lake Chelan National Recreation Area (Zone 697)-East Washington North Cascades (Zone 698)- Methow Valley (Zone 704)-Okanogan Highlands and Kettle Mountains (Zone 699)-Okanogan Valley (Zone 703).
ID...None.