THE WEATHER

1/31/2008 Weather Discussion: Moderate to heavy snow and lowering temps are expected to continue for the next 24 hours. We will see some windy periods as well. Long-term models show this winter storm cycle continuing through the weekend and beyond. There is some uncertainty about the weekend details so I will leave that until tomorrow. Forecast from Thursday 4pm to Friday 4am Precipitation .5-.75 in. Water 6-10 in. Snow Temperatures Low 22 High 26 Winds 5-10 W gusty Forecast for Friday 4am to 4pm Precipitation .25-.5 in. Water 3-6 in. Snow Temperatures Low 18 High 24 Winds 10-20 W TRENDS AND TIMING Precipitation: Moderate snow expected to continue through tomorrow afternoon. Precipitation is expected to lighten up late Friday evening into early Saturday morning. Freezing levels: Freezing levels expected to slowly drop through the next 24hours reaching 1000’ or lower by Saturday morning. Rising freezing levels are showing up for the weekend. Winds: A steady westerly wind pattern will be the norm for the next 24 hours. A frontal wave is expected to move through around midnight which could bring a period of strong 40+ winds for the early morning hours. Wind should subside through the day.

THE WEATHER

1/30/2008 Weather Discussion: A break in the snow is expected for today. We could have a very similar night as last night with a bit less wind. Snow is expected to continue until Friday. Long-term models show a break in the action Friday with another system moving in for the weekend. Forecast from Wednesday 4pm to Thursday 4am Precipitation .75 -1 in. Water 8-12 in. Snow Temperatures Low 24 High 30 Winds 5-10 W Forecast for Thursday 4am to 4pm Precipitation .25 -.5 in. Water 4-6 in. Snow Temperatures Low 20 High 26 Winds 0-5 W gusts TRENDS AND TIMING Precipitation: Light snow is expected to the rest of the day. Snow should intensify tonight with the heaviest period between 7pm and 4am. Snow intensity should taper some tomorrow. Freezing levels: Models are indicating a spike in the freezing levels to 3000/3500’ sometime after 7pm tonight. Temps should be back down below 2500’ by 4am. Winds: The winds should be reasonable for most of the day. The temperature spike this evening may produce a late night gusty period but this should be short lived as well. Light westerly winds with some gusty periods expected tomorrow.

POWDER FORECAST

1/29/2008 Weather Discussion: A strong NW jet stream will continue to drive winter storms into the PNW for the rest of the week. There wont’ be much of a break before another organized system hits tomorrow night. Temps will remain cool along with some gusty winds tonight. Long-term models show the northern jet stream holding its NW pattern through the weekend. There are some indications of warmer air invading by the weekend – we will have to keep an eye on that as the week progresses. In the mean time enjoy the epic powder. Forecast from Tuesday 4pm to Wednesday 4am Precipitation .75 -1 in. Water 8-14” in. Snow Temperatures Low 20 High 24 Winds 5-15 W gusty Forecast for Wednesday 4am to 4pm Precipitation .25 - .5 in. Water 4-6 in. Snow Temperatures Low 22 High 26 Winds 5-15 W gusty TRENDS AND TIMING Precipitation: Heavy snow will continue through the night. Storm totals will be measured in feet as a Puget Sound Convergence Zone develops this afternoon. Snow will lighten up after 4am tomorrow. The next systems ETA is after 4pm tomorrow. Freezing levels: Freezing levels will be between 1 and 2000’ for the next 24 hours. Surface temps should hold in the lower 20’s for the next 24 hours. Winds: Expecting a wind shift from east to west with the passage of today’s cold front. The potential for gusty convergence winds will grow through the afternoon and evening.

THE WEATHER

1/26/2008 Weather Discussion: A cold front will drop down the coast today bring some good snow to the mountains. Tomorrow will change to an intermittent snow shower pattern with not much accumulation expected. Long-term models show a few days of snow showers before a more organized system drives in on Tuesday. Forecast from Saturday 4pm Sunday 4am Precipitation .25 .5 in. Water 4-8 in. Snow Temperatures Low 20 High 28 Winds 5-10 SW Forecast for Sunday 4am to 4pm Precipitation Lt .25 in. Water 1-3 in. Snow Temperatures Low 18 High 24 Winds 0-5 W TRENDS AND TIMING Precipitation: Snow should intensify through the day. Heaviest precipitation period will be between 4pm and 2am this evening. Snow should taper off in the early morning hours. Light snow showers expected to linger through the day tomorrow. Freezing levels: Freezing levels expected to drop to 1000’ by 4pm tomorrow. Freezing levels will remain very low through mid week. Winds: The current SW flow will slowly swing to a west through the day. A well establish NW flow by will take shape by Monday. The center of the low is right on the coast, this will actual shield us from any strong winds associated with the frontal passage.

THE WEATHER

1/25/2008 Weather Discussion: The big storm hitting California will actually affect our weather here in the NW by driving up warm air. Therefore we should see temperatures rise through the next 24hours. A cold front is expected to move through the PNW tomorrow morning bringing snow to the mountains for the second part of the weekend. Long-term models show a cool NW flow developing Sunday and continuing for most of next week. This should bring us back into a snowy pattern for a week or so. Forecast from Friday 4pm to Saturday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 16 High 20 Winds 0-5 SE Forecast for Saturday 4am to 4pm Precipitation Lt .25 in. Water 1-3 in. Snow Temperatures Low 22 High 30 Winds 0-10 SW TRENDS AND TIMING Precipitation: An interesting split in the moisture regime has the forecast models confused, therefore exact details will be a challenge. Snow will slowly develop through the day tomorrow with the main wave passing between 4pm and 4am. A relatively dry period is expected on Sunday. Things should organize better later Sunday and Monday – so not expecting any significant accumulations until then. Freezing levels: Freezing levels will briefly spike up to 3500’ by noon tomorrow. Temps should then drop over night as the cold front drops down from the north. Winds: East flow should slowly give way to a SW flow overnight. There could be a mild gusty period tomorrow but should be short lived. A cooler NW flow is expected in the wake of tomorrow night cold front.

THE WEATHER

1/24/2008 Weather Discussion: We will have a couple more days of dry and cool weather until things begin to change on Saturday. Long-term models show snow returning on Saturday and Sunday. Jet stream models show the northern jet setting up for a NW flow by early next week. This shows promise for another storm track development. Forecast from Thursday 4pm to Friday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 12 High 24 Winds 0-10 E Forecast for Friday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 14 High 26 Winds 0-5 SE TRENDS AND TIMING Precipitation: No moisture expected until after 4am Saturday. Freezing levels: Warmer air will encroach from the south tomorrow evening. This will briefly raise freezing levels to near pass level tomorrow night. A cold front is expected to follow Saturday morning which will drop temperatures for the weekend. Winds: East flow will strengthen as these fronts approach. East flow should be overtaken by SW flow sometime early Saturday morning.

THE WEATHER

1/23/2008 Weather Discussion: High pressure parked over the eastern basin will keep the mountains dry through Saturday. Cold nights will remain the norm with slightly warmer day time temps as the week progresses. Long-term models show a system sliding down the coast on Saturday. Beyond the weekend looks promising for a change back to wetter weather. Forecast from Wednesday 4pm to Thursday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 12 High 20 Winds 0-5 E Forecast for Thursday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 14 High 24 Winds 0-5 E TRENDS AND TIMING Precipitation: No precipitation for the mountains through Saturday. Freezing levels: Freezing levels will inch its way up to about 3000’ by Friday. East flow along with cold nights will hold down surface temps through Friday as well. Winds: East flow will stay around until Friday.

THE WEATHER

1/22/2008 Weather Discussion: Dry, cold weather will continue through the rest of the week. Long-term models show a system sliding down the coast on Thursdays but it does not look like it will make it to the mountains. The long-range jet stream model puts the next chance of any significant moisture for the mountains on Sunday. Forecast from Tuesday 4pm to Wednesday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 8 High 16 Winds 0-5 E Forecast for Wednesday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 10 High 24 Winds 0-5 E TRENDS AND TIMING Precipitation: No moisture expected in the mountain until after Friday or even Saturday. Freezing levels: Another cold 24 hours with very low freezing levels. Single digits expected again tonight. The general temperature regime will inch up for the middle of the week. More cold air from the north is expected by the weekend. Winds: Off shore/east flow will remain in place until Wednesday.

THE WEATHER

1/20/2008 Weather Discussion: The cold front heading south will allow dry artic air to rush down and out of the Fraser River valley. This will create cold windy conditions throughout the state for the next few days. Long-term models show it beginning to warm up on Tuesday. A return to unsettled winter weather with cold temperatures is expected by the weekend. Forecast from Sunday 4pm to Monday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 10 High 16 Winds 10-20 E gusty Forecast for Monday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 5 High 16 Winds 10-20 E TRENDS AND TIMING Precipitation: No precipitation expected for the next 48 hours after this mornings flurries. Freezing levels: Freezing levels will drop to sea level by 10pm tonight. Winds: Strong off shore winds will push through the pass starting around noon today -could see gust to 40 as the gradient increases through the next 12hours. Models are showing winds subsiding by noon tomorrow. East flow should stay in place until Tuesday.

THE WEATHER

1/19/2008 Weather Discussion: Light mountain snow will continue today. Tomorrow will be dry and cold. Very cold temperature and a stiff wind will be the topic of conversation for the next few days. Long-term models show the cold air mass remaining in place until Tuesday. Thing will begin to warm up by the middle of the week. 7-10 day jet stream models are starting to indicate a return to a potential storm track by the end of next week. We will keep and eye on that potential as we try to stay warm for a few days. Forecast from Saturday 4pm to Sunday 4am Precipitation Lt .10 in. Water Trace in. Snow Temperatures Low 18 High 25 Winds 0-10 N Forecast for Sunday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 12 High 20 Wind chill - 0f Winds 5-15 E gusty TRENDS AND TIMING Precipitation: As suspected, the snow amounts have been downgrade for today. Probable won’t get much more than a .25” of water. Radar shows another push of snow that should arrive this afternoon – could see 1-3 more inches of snow before its all said and done. Freezing levels: Freezing levels will slowly drop through the day. Cold arctic air will begin to flow in from the NE tomorrow morning dropping freezing levels to sea level and below by noon tomorrow. Fidget temps will stay around until at least Wednesday. Wind chills could easily by well below zero by tomorrow afternoon. Winds: A north than northeast swing will occur overnight. A chilly E flow will rush through the pass tomorrow and Monday. Could see easterly wind gust above 20mph tomorrow. BURRRRR.

THE WEATHER

1/18/2008 Weather Discussion: The dry weather will continue through the night. Snow will be on the menu tomorrow as a system slides in from the north. Sunday things should dry out and cool down. Long-term models show cold air from central Canada moving in for the start of the week. This will bring very cold temperature and a dry air mass for next week. Forecast from Friday 4pm to Saturday 4am Precipitation Lt .10 in. Water trace in. Snow Temperatures Low 24 High 32 Winds 0-10 NE Forecast for Saturday 4am to 4pm Precipitation .25 - .5 in. Water 4-8” in. Snow Temperatures Low 24 High 28 Winds 0-10 NE TRENDS AND TIMING Precipitation: Snow should show up in the mountain after 4am tomorrow. Moderate snow should begin to taper Saturday night and begin our next dry trend on Sunday. Freezing levels: Freezing levels will slowly drop as the cold front moves in tomorrow. Freezing levels will drop below 3000’ by tomorrow noon. Cold NE flow will drop freezing levels to sea level by Sunday afternoon. Winds: A north/northeast flow will remain in place until Sunday’s NE push. NO huge wind events expected with tomorrows front.

THE WEATHER

1/17/2008 Weather Discussion: High pressure off the coast will produce a few more dry days for the PNW. Ridge top convection clouds will pass through from time to time but should be dry until tomorrow night. A system is flowing in from the north tomorrow night that will bring light snow to the mountains for Saturday. Long-term models shows a cold dry Canadian air mass moving in on Sunday. This could bring us very cold temps and dry weather for most of next week. Forecast from Thursday 4pm for Friday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 12 High 24 Winds 0-5 N Forecast for Friday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 24 High 30 Winds 0-5 N/NW TRENDS AND TIMING Precipitation: Models indicated snow developing after 4pm tomorrow night and continuing into Saturday. Saturday is looking to be a snowy and cool. Freezing levels: Cold air aloft flowing in from the north will keep surface temps on the cool side. Freezing levels will hover around 3000’ for the next few days and slowly drop over the weekend. Winds: A steady northerly flow will continue as cold air flows over the ridge of high pressure ridge. Wind should shift to NW flow later tomorrow. Could see a period of gusty cold winds tomorrow afternoon as the cold front drops in from above.

THE WEATHER

1/16/2008 Weather Discussion: High pressures will keep a dry weather pattern over the PNW for the remainder of the week. There is some moisture passing to our north, which could bring us a light snow shower or two. Cool nights and warm days will be the temperature regime for the next few days. Long-term models show a weak system sliding down from the north on Saturday. This may bring some snow and cooler temps to the mountains. A cool and dry air mass is expected to move in from Canada on Sunday. Forecast from Wednesday 4pm to Thursday 4am Precipitation 0 in. Water 0 in. Snow Temperatures Low 12 High 20 Winds 0-10 N/NW Forecast for Thursday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 16 High 24 Winds 0-10 NE TRENDS AND TIMING Precipitation: No moisture expected until Saturday. Morning fog burning off to broken daytime clouds will be the pattern for a few days. Freezing levels: Freezing levels will slowly rise to near pass level by Friday. However, daytime temps will take a while to recover from cold nighttime temps but the days should be progressively warmer through Saturday. Temps will then lower Sunday and Monday. Winds: A north-northeast flow should remain in place for a few days. This will help keep surface temp low along with cold nighttime temps.

THE WEATHER

1/12/2008 Weather Discussion: Building high pressure will slowly taper the snow off through the day. This will bring us a few days of dry and warmer weather – may even get a glimpse of the sun. Long-term models show a strong cold front arriving late Monday to give us another does of snow before strong high pressure bringS us dry cool weather for the remainder of the week. Forecast from Saturday 4pm to Sunday 4am Precipitation Lt .25 in. Water 1-3 in. Snow Temperatures Low 24 High 32 Winds 0-10 W Forecast for Sunday 4am to 4pm Precipitation 0 in. Water 0 in. Snow Temperatures Low 24 High 34 Winds 0-5 E TRENDS AND TIMING Precipitation: Snow should taper to showers through the day and come to an end by 10pm tonight. The following 36+ hours looks dry. The next precipitation is currently showing up for Monday afternoon. Freezing levels: Freezing levels will drop to around 2500’ tonight. Freezing levels are then expected to slowly rise reaching 5000’ by Monday morning. East flow should help to hold surface at or just below the freezing mark. Warm temps expected Monday until the cold front moves in later in the day. Winds: Could see a brief gusty period this afternoon as post frontal waves fill in behind the front. East flow should develop tomorrow as stay in place until Monday.

THE WEATHER

1/11/2008 Weather Discussion: The snow is expected to taper off through the day leaving us with a pretty quiet night. Snow is expected to return tomorrow, dry on Sunday with another system on Monday. Temps will bounce up and down with the passing of the fronts. Long-term models continue to show a strong high-pressure ridge developing midweek. This will cut off the storm track and bring dry weather to the PNW starting Wednesday and most likely continuing into the weekend. Forecast from Friday 4pm to Saturday 4am Precipitation Lt .10 in. Water trace in. Snow Temperatures Low 22 High 28 Winds 0-5 W Forecast for Saturday 4am to 4pm Precipitation .25+ in. Water 3-6” in. Snow Temperatures Low 24 High 34 Winds 0-10 SW TRENDS AND TIMING Precipitation: We should see a dry night with snow re-developing after 10am tomorrow. Could see and intense period of snow between 10am and 4pm but should be done by late afternoon. Sunday looks dry with another similar push or moisture on Monday. Freezing levels: Freezing levels will dip to 3000’ today. Freezing levels will briefly rise back up to pass level tomorrow by 10am but should quickly fall back down by evening. A similar event with warmer temps will happen on Monday. Winds: Gusty ridge top winds should subside today. Should be pretty mellow tonight. A SW flow will develop with the approach of tomorrow’s warm front.

THE WEATHER

1/10/2008 Weather Discussion: A steady Puget Sound Convergence Zone will produce heavy snow through the night. Freezing levels will bounce between 3000 and 4500’ a few times through the next 36-48 hours. Long-term models show a break tomorrow night before another snowy system moves through on Saturday. High-pressure is expected to develop late Saturday night producing a brief dry period for Sunday/Monday. The 8-10day jet stream model is still showing the northern jet pushing way north by the middle of next week. This has the potential to break the storm track for a while. Forecast from Thursday 4pm to Friday 4am Precipitation 1 -1.5” in. Water 12-16” in. Snow Temperatures Low 28 High 34 Winds 5-15 W gusty Forecast for Friday 4am to 4pm Precipitation .25 in. Water 4-6” in. Snow Temperatures Low 28 High 34 Winds 5-15 W TRENDS AND TIMING Precipitation: A Puget Sound Convergence will be in full force through the night. This has potential to push storm totals to the 2-3”of water range. The snow machine should be pretty much done by noon tomorrow. Freezing levels: Freezing levels will peak between 4 and 4500’ today and stay there until noon tomorrow. Freezing levels are expected to fall through the day tomorrow to 3000’ and then rise back up on Saturday to near pass level once again. Winds: Consistent westerly winds with gusty periods should continue to blow through the night. Winds should start to mellow by 4pm tomorrow.

THE WEATHER

1/9/2008 Weather Discussion: Snow should taper to showers today as the weak high-pressure ridge moves east of the crest. The next system will enter the mountains tonight. This system looks very similar to yesterdays storm. Snow with warmer temperatures will be possible through Friday. Long-term models show snow tapering off Friday with mountain snow showers through the weekend. Models are currently showing Saturday’s storm tracking north - this will bring warmer temps and some precipitation, but for now it’s not looking all that major. Early indications of a shift in the jet stream are showing up on long term jet stream models. This could be a sign of a change in our weather pattern sometime next week. Forecast from Wednesday 4pm to Thursday 4am Precipitation .25 -.5 in. Water 2 - 6 in. Snow Temperatures Low 20 High 24 Winds 0-5 E/SE Forecast for Thursday 4am to 4pm Precipitation .5 in. Water 4-8” in. Snow Temperatures Low 22 High 32 Winds 5-15 W gusty TRENDS AND TIMING Precipitation: The main front of moisture should reach the mountains after 10pm tonight. Snow expected to increase in intensity after 2am and continue through most of the day. Storm totals by Friday afternoon could be near 1-2” of water. Models are showing the potential for a Puget Sound Convergence Zone tomorrow afternoon and evening. Freezing levels: Freezing levels should hold steady through the night. A warming trend driven by isentropic lifting * will begin early tomorrow morning. Freezing level could push to 3500 -4000’ by noon tomorrow and hold there into the weekend. Winds: Westerly flow will give way to a short period of east flow as the front approaches the mountains tonight. West winds will then kick in by 7am tomorrow. Could see some periods of gusty westerly winds through the Pass tomorrow. *Todays weather lesson: Isentropic Lifting - This is the mechanism for the swing in winds from east flow and west flow, as well as, a way to achieve inversion layers. We could see this develop in the next few days as warm air from the west overrides the cold air "trapped" in the eastern basin. The science: The density varies between cold air and warm air with cold air being relatively more dense. Due to the higher density, cold dense air sinks to the surface and has a high resistance to being lifted in the vertical. In a differential advection situation, relatively warm air will lift over shallow surface cold air because the warm air is less dense. The idea of isentropic lifting is air "prefers" to move toward a region with the same density (potential temperature surfaces (a.k.a. along a constant theta surface)). Warm air resists undercutting cold air. To stay at the same density (by preserving potential temperature) it must override the cold air. The depth of cool air on the cool side of a warm front generally increases moving to the north of the surface warm front boundary. As warm air advects over colder air, it advects to a higher altitude above sea level as it moves north of the warm front boundary. The warm, less dense air rises gradually in the vertical as it overrides the sloping cold dense air (less potential temperature air).