Marine Weather and Tide Forecast for Ponderay, ID

SYNOPSIS
Temperatures will gradually trend warmer into early next week.
Active weather returns Tuesday night into Wednesday, with mountain snow, lowland rain, and breezy winds. This is expected to bring winter travel conditions over the mountain passes.

DISCUSSION
Tonight - Monday: It will be a quiet start to the weather pattern heading into the first week of March for the Inland NW courtesy of high pressure aloft. This will result in a combination of clear to partly cloudy skies with mainly cirrus or high clouds coming around the northern periphery of a storm system passing well south of the region through Northern CA and Great Basin.
Nights will be cool with temperatures dipping into the 20s-30s then rebounding into the 40s-50s each afternoon.

Tuesday - Friday: An active and progressive weather pattern returns to the PacNW as a series of Pacific troughs traverse the region. The first will arrive on Tuesday delivering light mountain precipitation mainly in the form of rain or wet snow with minimal impacts. A deeper system arrives on its heels early Wednesday with cooler air and deeper moisture. Snow will become more common for the mountain passes with light to moderate amounts and moderate potential for winter travel conditions.
Away from the Cascade rain shadow, lowlands can expect a 60-90% chance for rain on Wednesday. In the lee of the Cascades, rain chances are closer to 30-50%. Precipitation will trend more convective Wednesday afternoon with the arrival of 500mb temperatures between -28C and -30C. Models are hinting at signs of surface cape ranging anywhere from 50-300 J/kg. Would not rule out a few lightning strikes but probabilities for lightning at this time remain below 15%. A third trough arriving on Thursday will usher an additional push of cooler air with continued snow showers for the mountains and mix of rain/snow/graupel for the lowlands. Winds will undoubtedly become breezy through the period, especially Wednesday and Thursday with the exchange of air masses. Not seeing much in the way of anomalous pressure gradients or gusts on the ensembles which is indicative for more typical gusts in the 25-35 mph range.

Saturday-Sunday: A transition back to upper-level northwest flow with broad ridge of high pressure over the Ern Pac and strengthening Polar jet coming across the Gulf of AK and into western Canada. The pattern is similar to what occurred just this past week with the main storm track crossing through north- central BC/Alberta/Saskatchewan. This equates to a dry forecast in the lee of the Cascades and into E WA and showers in the mountains. The pattern is also conducive to breezy to locally windy conditions for the Inland NW. The main uncertainty comes with the exact track and depth of the surface low pressure systems to our north and how this equates to pressure gradients (winds) across Eastern WA/North Idaho. We are already seeing 30-50% chances for wind gusts of 30 mph on the day 7 forecast further supporting the increased confidence for a breezy period but when examining the GEFS/ENS members pressure gradients from Portland to Kalispel, there is nearly a 20 mb spread with GEFS/ENS means residing around +10-12 mb or west/southwest winds. Roughly 10% of the members indicate a negative gradient supporting the ridge further offshore and cooler air driving down the Northern Rockies suggesting reverse or northeast/east flow. This has very little support from the 100 member ensemble though still in the realm of outcomes. /sb

AVIATION
18Z TAFS: VFR conditions will continue through the period with middle and high level clouds drifting in from the south. Winds will be light, following diurnal directions.

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 29 51 31 53 34 53 / 0 0 0 0 0 10 Coeur d'Alene 30 51 29 52 33 53 / 0 0 0 0 0 20 Pullman 33 52 35 52 34 53 / 0 0 10 10 0 10 Lewiston 37 55 39 57 37 59 / 0 0 10 10 0 10 Colville 27 51 28 52 31 50 / 0 0 0 0 0 20 Sandpoint 28 48 30 49 33 49 / 0 0 0 0 0 20 Kellogg 31 51 32 51 34 53 / 0 0 0 0 0 20 Moses Lake 30 55 31 56 34 55 / 0 0 0 0 0 10 Wenatchee 34 52 36 57 37 53 / 0 0 0 0 0 20 Omak 31 50 33 52 35 50 / 0 0 0 0 0 10

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