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Blog Entries posted by Weatherman

  1. Weatherman
    This MLK weekend promises to be a great one for the New England skier. We're facing a sizable snowstorm Saturday night through Sunday. Look for widespread accumulations of a foot or more across ski country. Amounts will be highest in the White Mountains and southern Vermont, with less amounts as you move north into Vermont. Cutting to the chase, here are the latest snowfall forecasts from the National Weather Service.

    I think those amounts look like a decent guess for New Hampshire and Maine, but are overdone in Vermont. Yesterday's guidance was putting on crazy numbers over New England. For that reason I held off issuing a forecast until today when a more realistic picture has emerged. The most stable story so far as come from the European's model ensemble average. As ensemble is the same model run over and over with slightly different conditions and averaging the results, which gives a broad expected value. For a while now the European ensemble has been showing an average snowfall of about 15".

    As much as I'd like to drone on about the snow, I think that misses the main story of this storm. There will be plenty of cold air pouring into New England which should ensure snow in ski country, but it creates a strong frontal boundary across southern New England and coastal regions. The headline maker in this storm very well may be significant ice accumulation along the coastal front. The both the GFS and European model show this clearly. Below is a model forecast for Sunday afternoon from the GFS, and a total accumulated freezing rain from the ECMWF.

    Both models show a band of heavy icing across southern New England. This would lead to widespread power outages. However, I think the story may not be quite so dire. Especially considering it is a few days in advance, I think the models are underestimating the cold air at the surface. Surface temperatures just west of Boston look to stay in the teens throughout Sunday. Not only will the preceding air be cold, there are strong signs of this cold air reinforcement in the model vertical profile. Note the winds out of the north and northeast at the lowest altitudes. This should be cold enough and deep enough to yield sleet rather than freezing rain, but we'll need to revisit this as the day approaches.

    But if you're reading this, you probably care more about skiable snow totals. The easiest statement I can make is that I expect a little over an inch of liquid equivalent precipitation across much of the region. The storm is so progressive (quick moving, positively tilted, nearly open low) that it's hard to imagine much more than this inland of the coastal front. How this translates into snowfall depends strongly on the snow-to-liquid ration (i.e., the fluff factor). A rule of thumb of 10:1 ratio suggests a broadly distributed accumulation of 12-15" consistent with the weather service's forecast for NH and ME. You can see this in the latest mesoscale guidance if you ignore the numbers over southern New England where sleet will likely keep numbers way down.

    But what about if the snow is fluffier? This possibility is supported by the surface temperatures in the teens. That's plenty cold enough for ratios up to 20:1, assuming that those temperatures are maintained in the snow growth zones aloft. Using the same liquid equivalent precipitation and allowing for the ratios to vary with the surface temperature you forecast accumulations close to two feet in northern New England, and greatly reduced accumulations in southern New England. The fluff factor is going to be the decider in the snowfall guessing game.

    So what's the realistic expectation? Probably a mix of these two possibilities. The GFS gives a reasonable first guess.

    Note the starkly difficult accumulations over the Lakes Region of NH vs the White Mountains. What's driving this difference? It's the temperature profile aloft and where that places the dendritic growth zone (DGZ). That's the region of roughly -10 to -20 Celsius. To maximize snowfall, you want a deep region of these temperatures that also has saturated air rising upward. That maximizes the product of dendrites, which are the classic fluffy snowflakes that you are probably imagining. The temperature and humidity profile in the atmosphere can lead to a variety of snowflake shapes.

    Looking back at that snowfall forecast disparity between the NH lakes and mountains, let's look at the model's vertical profile forecast. First the Lake Region:

    Note the narrow dendritic grown zone (DGZ) show on the left column with the red dashed lines. The red-purple bars are the air's vertical motion expressed in pressure-based coordinates (omega) where negative omega values mean the pressure following an upward-moving air parcel is decreasing. Even though this region has saturated air and strongly upward lift, the DGZ is narrow and most the prime snow generating region will produce other shapes of snowflakes leading to a lower fluff factor. A similar plot just to the north over the White Mountains will show a slightly colder profile, but a greatly expanded DGZ and therefor higher fluff factor.

  2. Weatherman
    Good news skiers!
    Friday night will bring an elevation snow storm to northern New Hampshire and Maine. After getting off-piste in 15" of natural on October 27 at Wildcat, this is more welcome news. Sorry, Vermont skiers. Once again you'll be missing out. The thermal profile is such that the valley will likely not see any accumulation. This is likely going to be something that only accumulates about about 1,700 - 2,000'. Look for snow in the notches and mountains, but not the low terrain. 
    Best place to ski this weekend? Hands down Wildcat again.

    After the storm moves through, we'll enter into a prolonged snowmaking window.  We're looking at several days (at least a week) of below-freezing weather that should allow a lot of mountain to open going into mid-November. Below is the 5-day temperature anomaly map for heart of the window.

    Before people criticize me for not mentioning it...  yes, there is a chance of a substantial snow storm next Tuesday. For those ski areas that choose to operate mid-week (that's a short list), there could be some great skiing. We'll have more on that when we actually have a better handle on what to expect. In the interim, here's your teaser:

  3. Weatherman
    Wax those boards, boys and girls. We have a genuine powder day coming up on Saturday, in October! Powder might be a bit of a stretch. Dense snow is expected. A paste job is likely.
    This weekend we'll be skiing at 4 mountains in New England: Mt Snow, Killington, Wildcat, and Sunday River. Of those, Wildcat is easily the best bet. They reported nearly 10" of fresh snow today. They are likely to receive the most snow on Saturday, and they are offering top-to-bottom skiing off the express quad. Look for total daytime snow accumulation at Wildcat on the order of 4-6" on Saturday.

    Despite talk of strong winds, I am not expecting it to be an issue at Wildcat on Saturday. Overnight the snow is likely to turn to a mixed bag, and then do rain on Sunday morning. It remains to be seen if we can sneak in some good runs on Sunday morning before it completely changes over. 
    What is the ski of choice for this weekend? 90-something mm underfoot seems like the right play. And rock skis will be a must. Depending on conditions, poaching may be called for.
    Next week looks like continued cool and unsettled, but mostly rain, in the the early week. Warmer weather moves in late week, and turning cooler again for next weekend.
  4. Weatherman
    Attention snowmakers: I hope you rest up tonight, because Wednesday night shortly after dark it will be time to get down to business. We're expecting at least two prolonged snowmaking windows. The first Wednesday (10/16) night into Friday morning, and another Saturday night into Tuesday morning. Below is a modeled temperature timeline for Jay Peak. Note that temperatures on Sunday and Monday may not stay cold enough to allow daytime snow production.

    With the arrival of the cold air on Wednesday night, we should see some accumulating snowfall at elevation in northern New England. Except for a stay coating which will quickly melt, don't expect any impact at lower elevations.

    So will we get any skiing in this weekend? That really depends on what daytime temperatures and humidity do during the day Thursday. Dewpoints in the teens mean that humidity won't be an issue. At the moment it looks like high temperatures should stay cold enough for productive snow making above about 2500 feet. It's possible we'll have upper mountain skiing on offer at Killington and Sunday River this coming weekend. If base depths aren't there in time, skiing early next week seems like a safe bet. By the weekend of October 27, anybody who wants to open should be able to do so. A third snowmaking window setup late next week Wednesday into Thursday.

    Looking past the weekend of October 27, the pattern turns warmer. The days surrounding Halloween should be back above freezing with temperatures trending near to above average. Beyond that is too far to see.

  5. Weatherman
    The time for stoke is now. Are you ready? October skiing is highly likely this year. So when does it start? Look for snow guns to come alive this Wednesday evening (October 17). Thursday night will be even colder. Look for a hard freeze almost all the way down to the coast.

    Below is the National Weather Service temperature forecast for Killington Peak.

    Freezing temperature should be widespread Wednesday and Thursday nights. Most ski areas should lose snowmaking temperatures at the base during Thursday afternoon, but should maintain them at elevation. A few higher elevation areas like Wildcat may be able to maintain top-to-bottom temperatures throughout Thursday. But none of those areas tend to blow top-to-bottom so early in the season. Below is a chart of Thursday afternoon temperatures.

    It's too early to say whether we will see turns being made this weekend at typical early players like Sunday River, Killington, or Bretton Woods. We'll have to wait until we see exactly what conditions materialize before we make that call. But I strongly expect to see skiing by Saturday, October 27. Next week looks to be well below average in temperatures. There should be multiple nightly snowmaking windows. Most ski areas that want to have October skiing should be able to do so. Below is the 5-day temperature anomaly forecast leading up to that Saturday.

    Get stoked! I'll be doing some ski tuning this week.
  6. Weatherman
    It's no secret that March is the snowiest month of the year, and fortunately this year looks to preserve that generality.  A Nor'Easter will impact the region on Wednesday bringing snow stretching into Monday morning. Widespread moderate to heavy snow is expected from a band of 8-14" stretching across much of ski country. Locally deeper snowfall is possible, but moderate temperatures should limit the fluff factor keeping accumulations down. The latest GFS snowfall forecast will give you a general idea of the pattern.

    For much of the area, especially at lower elevations, expect a wet snow paste job. It'll make excellent base snow, but don't be looking for a blower powder day. As it stands the surface temperatures should be borderline in many areas, but plenty of cold air exists aloft. There will be little to no chance of mixed precipitation, so icing is not a concern. The skew-T below from the Monadnocks shows the plentiful supply of cold air aloft and deep later of moisture.

    What does the mean for skiing? Wednesday night should be fun where night skiing is available at places like Shawnee Peak, Gunstock, Pats Peak, Crotched, and Wachusett -- though temperatures at the latter bear watching for any rain mixing in. Thursday morning should bring knee-buster snow to much of central New England. Even higher elevation areas like Wildcat and Cannon will be looking at dense, though hopefully drier, snow and not champagne. Accumulations in northern Vermont will be lighter on Wednesday night as is typical with coastal storms. For Thursday I'd head to northern New Hampshire in search of dryer snow even if accumulations aren't as high. It'll be a hunt for quality over shear quantity. Given that Wildcat already has natural terrain open (with very thin and scratchy cover) courtesy of last Friday's nsow, they look like the best bet.
    As the low passes southern New England, it is expected to wrap up and move onshore into Maine. By this point snow should be wrapping up in southern New England, but the next phase of the storm will start, and this one isn't being discussed much yet. Expect the talking heads to catch up with it soon. The potential of heavy upslope snows exists for the Friday timeframe at which time the low will be inland. Wrap-around flow will be pumping Atlantic moisture into the spine of the Green Mountains. I'm not touching any potential accumulations so far out with an upslope event, but the typically favored upslope areas look to be in great shape. I'd start thinking about making plans before things get booked up.

    The plan for this weekend depends on what type of skiing you're looking for. For skiing groomers with maybe a little off-piste, southern Vermont looks to be in the best position given the snow they received on Friday coupled with Wednesday's upcoming storm. Groomed trails should be in great shape. If you're a powder hound looking for the trees, head to northern Vermont. Given the upslope nature and current base depths, Bolton, Stowe, Smuggs, and Jay are looking promising for the weekend. A bonus wild card in Bretton Woods who will do okay on Wednesday and can make out well from upslope flow. They have practically zero base depths already, but New England's only lift-serviced golf course doesn't need much snow to open its ungroomed terrain.
    Looking to next week, there is another chance of a storm in the early week (Tuesday?) timeframe. Then things should moderate back towards spring conditions in time for St Patrick's Day weekend. With natural snow on the ground, it could be a beautiful weekend.

  7. Weatherman
    For the past few days I've been carefully watching the development for Friday's coastal storm. The greater than usual uncertainty has been the result of two key factors: 1) the thermal profile is going to right on the cusp between snow and rain, and 2) the system is going to be highly energetic. Robust storms like this one are difficult to forecast since the perturbations enter a non-linear regime meaning small changes in computer model inputs can result in dramatic differences in the forecast. Model solutions have ranged from a non-event to a crippling blizzard of historic proportions.
    As the storm draws closer, we're starting to get a better handle on the uncertainty. Nothing in out of the question yet, but here is the general idea...
    A cut-off low will approach southern New England and then drift off to the south. The primary impacts of the storm will largely miss ski country. Heavy snow is likely to confined to upstate New York.

    Expect strong on-shore flow keeping the thermal profile above bringing heavy rain to southern New England. Snow will be limited to higher elevations, except at the tail end where the snow level may drop enough to bring pasty snow toward lower elevations. Areas like the Monadnocks, southern Greens through the Berkshires, and Worcester hills stand to get higher than forecast snowfall totals if the thermal profile changes much. The Catskills look to be in the best position for reliable snowfall out of this storm. Across southern New England, several inches of rain likely somewhere in a band where the low-level jet is the strongest.

    But this really isn't a story focused on rain or snow, at least not on its own. Instead this is going to be a story about severe coastal flooding and widespread power outages. There is still a lot of time for things to change, but multi-day power outages are a strong possibility. To highlight the strength of this storm, check out the pronounced tropopause fold that is forecast. You're probably thinking either a) what the hell is that? or b) cool! but get to the point. The tropopause fold itself is not on consequence to this story, but is a symptom of how robust the storm will be.

    A strong low-level jet is going to bring onshore plenty of moisture and exceptionally strong winds just above the surface. It's unlikely, but possible, that this moisture could reach the ground as snow if the thermal profile cools, which would increase the potential for power outages as the pasty snow further burdens trees that will be exposed to damaging winds. But check out that low-level jet...

    Wind speeds at 850 mb (around 5,000 feet) are going to be on the order of 100 kts (115 mph) around Cape Cod. Yikes! It's an open question of how much of that mixes down to the surface, but expect widespread wind damage. Also another cool geek note: check out the gravity waves being shed from the exit region of the low-level jet off the coast of Virginia. There's definitely some numerical issues caused by the weather model, but they're just another sign of the energy in the system. Cool.

  8. Weatherman
    I'm happy to be able to put forward a remotely optimistic weekend outlook. Some light precipitation (of mixed phase depending on location) on Friday night will give way to a beautiful day. Saturday looks to be a warm and sunny days with temperatures in the 40s in the valleys, and 30s at the summits. But all eyes should be focused on Sunday, which looks like a classic warm air overrunning scenario. In these situations, Vermont typically starts as snow and switches over to straight rain. But northern New Hampshire into Maine can be a very different story where cold air damming hangs tough. Looking toward Sunday afternoon, snow may still be the dominant precipitation over the White Mountains and northeast into Maine.

    But the temperature profile is going to be borderline. The exact details will depend on to what extent a secondary surface low develops off the New England coast, which will help to reinforce the cold air damming. If this lows fails to develop, we could be left with freezing rain or a straight cold rain. Optimistically so far it looks like the White Mountains will see a 6 inch paste job on Sunday. For those of you savvy on Skew-T diagrams, note the deep layer of overrunning warm air all the way up to 650 mb. That nearly isothermal layer looks to stay just below freezing, and should lead to a pasty snow, but it won't take much of a shift to flip it.

    Updates will be necessary as the storm approaches.
  9. Weatherman
    I was on vacation for a while in late January in early February, so I am sorry for missing those couple of storms. Unfortunately the weather has taken a turn for the less favorable. Looking toward this weekend, I expect only light accumulations in the higher terrain.

    The school vacation week look warm. Very warm. And there will be some showers mid-week. Not exactly the most compelling ski conditions, but the kids won't be freezing.

  10. Weatherman
    I know that January was less than favorable for snow storms, which is why you didn't see a lot from me. Plus I was on vacation for the last ten days in the Dolomites and Venice, but I'm back now! I'm still trying to work through my backlog, but fortunately tomorrow's upcoming storm is a simple story.
    In short, there is a progressive wave coming through tomorrow (Wednesday) that will drop a quick 8-12" of snow across northern New England. As the center of the low will pass over southern New England, accumulations will taper off across the seacoast of NH and most of MA. The snow should start in the morning and taper off in the evening and be done by midnight across New England. Like most coastal lows, expect New Hampshire and Maine to do better than Vermont, though nobody should be disappointed. I've left out any specific model forecast maps, because I don't want to get too focused on where the exact rain / snow transition line sets up in any one forecast. Also given the nature of this system (a progressive wave), I don't expect orographic enhancement to be as big a factor as we would see with a closed coastal low (your traditional Nor'Easter).

    The thermal profile still appears uncertain over southern New England, so I'm not showing a track for the low. Look for it to pass somewhere between southeastern NH and southeast MA. The result is relatively uncertain accumulations, with 2-8" expected in the transition region around the Merrimack Valley.
    After the storm, cooler but still seasonable temperature return. It will be a chilly but tolerable late week for skiing, and then will moderate toward the weekend. A weaker wave of disturbed warmer weather approaches for this weekend. Enjoy the soft snow on Friday and Saturday, because the passing of Sunday's weather could lead to a wetter snowpack firming up on the back side. Next week's weather looks at best seasonable, with a lack of any sustained cold air.
  11. Weatherman
    Model trends today have been to the west, which is no real surprise. In this highly amplified flow the models tend to damp down such extremes in the long range. The way we initialize models (data assimilation) there are terms in the equations to penalize extreme solutions and force everything back to average. The result is often suppressing storms in highly amplified regimes like this one.
    The track looks to be just offshore with strong snow banding just to the west of the track. This bring heading snow bands to eastern coastal regions of New England from eastern Massachusetts into most of Maine. The White Mountains of New Hampshire into Maine will see a localized maximum as is common in coastal storms. For those of you in Vermont -- tough luck but that's no surprise. Your bread and butter are the lighter snow of upslope wrap-around. I don't mean that there won't be any snow -- there will be some upslope -- but when in these cold regimes it is the light and fluffy stuff that just serves as a top dressing. For skiers, it won't give you any float, it won't serve to reinforce the base, and it won't stand up to skier traffic. It will end up blown into the woods.

    If you look careful at the precipitation map above, you'll note the cellular pattern in the precipitation. This is the result of embedded convection within the snow band. In these intense snow storms, there can be pockets of elevated air that become unstable and rise upward like in a thunderstorm. This is in contrast to overrunning (stratiform) precipitation where moist air rides mostly horizontally from the south up cover cold air. The overrunning results in precipitation. Those same dynamics are at play here, but mesoscale (mid-scale) dynamics are at play that causes that overrunning area to have more energy than the air below it, resulting in overturning.

    A sounding from the model forecast above taken in southeast Massachusetts (where the red dot is) shows this. For the untrained eye, there are three things to see.
    Note the profile of "equivalent potential temperature" in the lower right. This is the temperature that the air would have if it was brought down to the ground and all the water vapor condensed. This should continue upward if the profile is stable. If it decreased with height, the air will want to convectively overturn and result in precipitation. Note the elevated unstable later around 800 mb pressure level, and a near surface instability area as well. This same unstable layer shows up in the Skew-T sounding in the middle of the page. The diagonal solid dash lines refer to lines of constant potential temperature, which are just subtly different from equivalent potential temperature -- just discounting the events of moisture. The green line is the dew point temperature, and red line is the air temperature. Where the red and green liens meet, the air is saturated. In the saturated layers, note the negative omega values in the bar plot in the lower left -- in dynamics omega is vertical velocity of an air parcel with respect to pressure. Negative omega means decreasing air air pressure and upward motion. Where the air is saturated is becomes buoyant and accelerates upward. Once the instability relaxes the upward motion slows. You can see this upward motions in the negative omega values in the two layers. The presence of these two unstable layers are likely due to two different mechanisms at play. The elevated, and stronger, unstable layer is the broad scale up-lifting. As snow falls from the upper layer into the lower, it will seed additional precipitation from the lower saturated level. This is a common situation with terrain-based enhancement and is know as seeder-feeder snowfall.
    S0o where does that leave us? The responsible NWS is showing a broad moderate snowfall, and that's the appropriate forecast at this time.

    Note that these maps don't accurately show expected terrain enhancements. The White Mountains will once again make out well from this storm. The global GFS guidance picks up on it, and the high resolution 3 km NAM really latches onto it.

    As previously discussed, convective dynamics are at play in this storm, and the global models do not have sufficient resolution to catch this. So give more credence to the NAM forecast in the lower plot.
    It's also worth noting that skiers may miss the real news worthy story. You'll hear talking heads on TV tossing around the B-word. That's a result of the strong winds being driven by the intense cold already in place that we're feeling when we go outside. The NAM is showing a taste of that.

    The heavier, wet snowfall in southeast Massachusetts couple with those strong winds could result in power outages. Those would be a big deal in this regime. We'll be returning to extreme cold on the backside of this storm. Those who lose power could be facing freezing pipes within hours of power loss. Temperatures will be diving sub-zero again across New England on Friday into Saturday. If you lose power, watch your pipes!

    So where to ski this weekend? Nowhere? Everywhere? Good luck. It's going to be damn cold. But the White Mountains will have the deepest snow pack in place, with depths in the high terrain approaching three feet. Secondary maximums are evident in the higher terrain of Vermont, but are not quite as deep, especially counting the water content of the snowpack which is helping to pad the New Hampshire numbers.

  12. Weatherman
    Please don't panic. Life will go on. But this Saturday it is going to rain. Vermont will get the worst of it. As is usually the case with these inside runner storms, the frozen precipitation will hold on the longest over the White Mountains of New Hampshire and into Maine. They made actually see a net positive gain in snow depths (base builder event) especially at places like Wildcat, Sunday River, and Sugarloaf that sit on the north side of the White Mountains. The high terrain can act as a protective barrier keeping the cold air locked in place for longer. It won't stay snow there, but it will contribute positively to the water load in the existing snow pack rather than melting it.

    The good news is that this may not ruin the whole Christmas week. For those of you with travel plans on Christmas day, please keep an eye on the forecast. Right it looks like a storm is brewing which will refreshen our snowpack bringing widespread snowfall to the higher terrain.

    So after a rain and then a snow storm, what is the net-net gain? The White Mountains look to come out nicely. It should be a great Christmas week for skiing in New Hampshire.

  13. Weatherman
    It's all about the base. Starting tomorrow we'll be seeing a storm system composed of two phases. The first phase will be a quick hit of light to moderate snowfall falling throughout the day.

    Late Friday night into Saturday morning we'll see a lull in the precipitation, followed by the onset of freezing rain on Saturday afternoon and evening. It's remarkable how consistent the models have been with this freezing rain for days now. Typically models don't handle freezing rain well as they generally lack the resolution, especially vertical resolution, to capture the dynamics of entrenched cold air damming. This gives us confidence that significant freezing rain is expected, but I don't expect significant impacts. Because the freezing rain will be preceded by a snow event, the snow will act as a spongue and prevent significant glazing.

    When the storm is over, expect moderate accumulations of snow with a breakable crust across northern New England.

    Expect subzero cold to move in for the middle of next week. It'll make skiing unpleasant for long periods, but is not unexpected at this time of year. The larger topic of interest is a potential storm looking toward next weekend. It's too early for details, but I can't help but get excited.
  14. Weatherman
    The stars have aligned over the last 24 hours as the weather model guidance has decided that it's time for winter to get started. This a much more sensical solution as all the pieces were in place. The first development is that model guidance has shifted on-shore with Saturday night's snowfall. The result is a plowable snowfall across southeast New England, with light snow over the White Mountains of New Hampshire and western Maine. Accumulations in Vermont won't be meaningful until later in the week.

    Another storm is expected on Tuesday which will track across New England and bring a mixed bag of precipitation. Right now it looks like a solid base-building snow event for the White Mountains on New Hampshire. Details are still sketchy this far out, but the model runs have been more consistent than usual for this range of a forecast bring snow to the mountains and rain to the coastal plain. The latest GFS model forecast below illustrates that the rain-snow line will be a question in play, but just inland of the line it's looking like several inches of mixed precipitation or wet snow.

    After these two systems pass, the cold sticks around for the foreseeable future. Stay tuned as much snow events are likely.
    10:45 PM Update:
    With the latest round of guidance coming in, we're finally at the point where the high-resolution models are in range. And terrain enhancement in the White Mountains is looking good. I'm upgrading this to a Powder Day Watch. Carrying wider skis with you this weekend is recommended. Something in the 95 - 100 mm width range is recommended for Sunday. About 6" of fresh is expected for first chair at Wildcat on Sunday.

  15. Weatherman
    Temperature Outlook
    Cold air is moving into the Northeast today, and it will be here to stay for the foreseeable future. The long range forecast is for below-average forecast at least the next two weeks. Snowmakers will be working overtime. Below are the surface temperature anomalies for the next two weeks.

    This Weekend
    This weekend looks tranquil with a low chance of very light snow -- not enough to do anything but look pretty. A wave low pressure should stay just offshore. There is still model disagreement with whether light snow will reach coastal areas, but it should stay far enough out to miss ski country. Below is one of the more snowy model solutions.

    For those of you attending our season kick-off and demo day at Bretton Woods on Saturday, expect highs in the 20s and calm wind. The snow should be hardpack after this week's rain. Hopefully a couple of grooming cycles will allow them to recover.

    No Snow?
    While the ingredients are in place, right now there's no sign of significant snow over the next several days. Anything beyond early next weeks remains uncertain, but nothing stands out at this time. The 10-day forecast shows only light accumulations, with the possible exception of the higher terrain of northern Vermont. There they could see a total of several inches of light, fluffy snow, but nothing of the quality needed to build a base.

  16. Weatherman
    This weekend
    December arrives on Friday! So where should you ski this weekend? That's an easy answer: Jay Peak. They've reported 22" of snow this week. Have you seen the reports? I'm jealous.  They already have several trails and a few glades open with natural snow.
    The snow isn't done yet. Another several inches (maybe 6?")  is expected before the weekend.

    If you're not skiing this weekend, this is your opportunity to complete preparations for winter. This may be your last chance. Finish leaf cleanup, and make sure the snow blower is functioning. But seriously, you should be going to Jay Peak. Start packing.
    Next week
    Temperatures will be seasonable this weekend, but warming up into early next week.

    Around Tuesday - Wednesday, expect a dramatic regime change. The transition itself should bring precipitation, though the details of how that happens remains unclear. From late next week onward we'll see dramatically more wintry weather. Expect ample cold air and opportunities for snow.

  17. Weatherman
    Ski areas across northern Vermont reported several inches of snow today. This is a classic case of upslope flow, and it usually leaves really powdery snow. The kind of fluffy snow that disintegrates as soon as you sneeze at it. Pure blower. Great for a top-dressing, but no good at building a base.
    @Flying Yeti writes...
    Most of the time the moisture from these events is wrap-around from a departing low, like yesterday's rain storm. The mesoscale models generally handle these post-storm snowfall events well. The trick is high-resolution models can resolve the terrain whereas the global model (GFS, ECMWF, etc) simply lack necessary resolution. Check out the 3km NAM forecast initialized at 12Z yesterday.

    The orientation of the lake-effect snow streaks illustrates how the flow is coming out of the northwest. The moisture from the lakes is not tracking toward Vermont. Notice how well the model picks up on the terrain enhancement of the snowfall. And check out the model sounding in the midst of the snowfall. Notice all the low-level moisture that is going to be forced over the mountains.

    If you're not savvy on reading the Skew-T diagram above, don't fret. There's a lot going on in it. I could teach a semester weather course and not manage to explain everything on that plot. For those looking for extra credit, UCAR offers a several hour crash course that assumes you already have a meteorology background.
  18. Weatherman
    The thermal profiles are timing are looking very close, but I've become more optimistic that there will be some good skiing to be had for this weekend. Let's break it down in brief.
    The White Mountains look to survive Thursday's storm with a net-gain of snow, especially at elevation. Just enough cold air is going to hang on aloft to counteract the  rain/snow changeover. The mixing line looks to go up to about 3,000 feet at times. Vermont will not be so lucky as they receive a little snow by mostly rain on Thursday. At least the mid-week timing will give snowmaking and grooming systems a chance to catch back up.

    The snow in the White Mountains will be the pasty variety that will hopefully freeze into place. Look for total accumulations of around 1-3" at low elevations, and on the order of 6" over the higher terrain at places like Wildcat.

    Saturday - Sunday
    Looking forward to the weekend, everybody is likely to see snow transition to all rain. The good news? The rain will fall largely overnight Saturday into Sunday. Right now it looks like the skiing hours will not be severely impacted by the rain. Saturday especially could have nice conditions in areas that receive a net benefit of snow this week. Below is the meteogram for this weekend in Pinkham Notch.

    Where should I go this weekend?
    It's definitely a White Mountains weekend. Wildcat looks to be in the best position, though they'll offer the least terrain options. Depending on exactly how things break, Bretton Woods, Loon, and Sunday River could all do well. 
    What comes next week?
    At least early in the week their will be a good snowmaking window following this weekend's storm. Around Thanksgiving Day the weather turns more questionable. There's a broad range of possible outcomes ranging from a Nor'Easter to blow torch warm. I'm not going to get pinned down on any specific forecast quite yet.
  19. Weatherman
    I'm looking at the forecast for the next several days, and I'm not impressed.  Thursday we'll see widespread rain across New England. The ECMWF model is holding onto a wet snow paste job across the White Mountains, but the GFS is going rain. Either way, the thermal profile is going to be close. I'm leaning toward a washout.
    On Saturday - Sunday, we'll see another wet weather system move through. That one looks to start as snow and quickly change to rain. I'd rather not dwell on this. My goal is to make this a ski weather blog... not a rain blog.
    Do I have any good news? On the back side of the storm we look to transition into long-lived cold weather in the East. Next week will bring sustained snowmaking weather for Thanksgiving. Let's put up some pictures with lots of blue! Below are the temperature anomalies for next week (top) and Thanksgiving Day (bottom). The net result will be plenty of productive snowmaking weather. This season looks to be off to a health start. Terrain expansion is come quickly.

  20. Weatherman
    Welcome to ski season 2017-18. This weekend we look forward to skiing at:
    Killington Sunday River Wildcat Mount Snow Okemo Sugarloaf Bretton Woods? -  Thursday
    Guns are off right at lower elevations during the day as the flow has turned out of the south bring in warmer and more humid air. We're getting squeezed between two circulation centers which is moderating the weather for now.
    In the early morning the flow flips around, and cold air pours into the region. Sub-freezing temperatures should extend all the way to the coast. Expect anyone and everyone who wants to make snow to do so. Near record cold temperatures mean an excellent stretch of production. Temperatures should be ideal for around the clock snowmaking.
    Snowmaking continues all day Saturday. By now you should be skiing at any of several open ski areas.
    Sunday and beyond
    Temperatures moderate to just above freezing during the day on Sunday. Below-freezing temperatures hold on a bit longer at elevation.
    Next week we enter into several days of seasonable temperatures with highs above freezing dipping into the 20s at night. It'll be an operations decision whether to make snow in marginal temperatures at night. The long term pictures looks favorable for continued cold in the East with opportunities for coastal storms. Signs look good!
  21. Weatherman
    Monday afternoon update
    It's finally here. The first turns of the 2017-18 ski season will be made this week! Snow guns will be firing up tonight across New England. Looking at who is already in play, expect Killington to be making their first passholder-only turns by the end of the work week, with other early season players coming on board by the end of the weekend. Sunday River has already announced a weekend opening, and Bretton Woods may join in. Exciting! Let's break it down day by day.
    Snow guns will be running in the early morning hours at elevation. Lower areas will hold off. Most areas will have to temporarily shut down during the day as temperatures climb into the 30s. Northern New England should be able to keep the guns on at elevation at places like Sugarloaf, Wildcat, and Stowe.
    Just about at dusk expect the snow guns to go online. Temperatures and humidity will be a prime for a early November window. At night snowmaking should be able to go all the way to the base.
    A lot like Tuesday. Guns go off during the day and come back on in the evening hours. For now temperatures look good to go for more top-to-bottom snowmaking that night, though will be warmer than Tuesday night and a shift of a couple degrees makes a huge difference. While not ideal at low elevations, it is a workable window.
    Guns go off at daybreak. It looks like conditions may not be favorable to a return to snowmaking until after midnight A short wave trough will be swinging through the area. If the current model solutions play out, look for two weak low pressure systems to pass to either side of us: one across central Quebec and another out to sea.
    With New England between two lows, expect us to be in a trough where winds turn out of the south and humidity rises. The result for us will be marginal at best snowmaking at best.
    After the trough passes through New England, expect temperatures to drop to stay below freezing all day. Sub-freezing temperatures should extend all the way to the coast. Expect anyone and everyone who wants to make snow to do so. Near record cold temperatures mean an excellent stretch of production.
    Snowmaking continues all day Saturday. By now you should be skiing.
    Next week
    Winds turn out of the south on Sunday, and temperatures rise above freezing by mid-day. The next system moves through late Sunday into Monday. It's too early for details, and rain vs snow remains to be seen. We'll keep an eye on it and let you know more as the time approaches.
  22. Weatherman
    Monday evening update is posted, previous discussion continues below.
    It's finally here. The first turns of the 2017-18 ski season will be made this week! But before we get there we need to weather some rain tomorrow (Monday) and be patient as the snow guns come online. Looking at who is already in play, expect Killington to be making their first passholder-only turns by the end of the work week, with other early season players coming on board by the end of the weekend. Exciting! Let's break it down day by day.
    It's going to be warm and rainy. The end.
    The first sub-freezing air hits in the early morning. Maybe a few aggressive ski areas start blowing in the early morning hours, but they'll likely have to temporarily shut down during the day as temperatures climb into the 30s.
    Just about at dusk expect the snow guns to go online. We're not talking about ideal snowmaking weather, but it'll get the job done in early November. In northern New England they should be able to make snow top-to-bottom, but that will be an operations decision.
    A lot like Tuesday. Guns go off during the day and come back on in the evening hours. For now temperatures look good to go for more top-to-bottom snowmaking that night, though again a shift of a couple degrees makes a huge difference. Once again temperatures will not be ideal, but it'll work if they want it to.
    Guns go off at daybreak. It looks like conditions may not be favorable to a return to snowmaking that night. A short wave trough will be swinging through the area. If the current model solutions play out, look for two weak low pressure systems to pass to either side of us: one across central Quebec and another out to sea.

    With New England between two lows, expect us to be in a trough where winds turn out of the south and humidity rises. The result for us will be marginal at best snowmaking that night.
    After the trough passes through New England on Friday, expect temperatures to drop that evening. Sub-freezing temperatures should extend all the way to the coast. Expect anyone and everyone who wants to make snow to do so.
    The weekend
    We're still a week out, but it looks favorable for continued snowmaking. Temperatures will likely stay cold enough to allow snowmaking throughout the daylight hours at elevation.
    Next week
    Monday may be a fun day! The next storm system will move through the area. Right now it looks like snow for northern New England. We'll keep an eye on it and let you know more as the time approaches.
    The extended period looks favorable as well. It looks like we'll be in a new regime of cooler weather in the East.
  23. Weatherman
    I'm settled in a home with two bowls full of candy awaiting the Trick or Treaters. Yes, we're running a bit behind this year due to Sunday's storm and the subsequent power outage. On top of that today is my wife's birthday, and my mother's. Yes, both of them. But today's multi-occasion theme has me in the mood to transition to welcome November news. Snowmaking will be coming online in the foreseeable future.
    Killington has proven a willingness to blow snow in the most marginal conditions, even if that means that it all melts. They'll get a brief window at elevation tonight. But the window will be very limited and marginal. I doubt that stops them.

    The situation looks a little better at Sunday River, and they may see another even more marginal window tomorrow night. It's an operations call as to whether the light up the guns. We're in for a warm-up early next week so they'd likely lose much of what they can put down.

    Early next week we're looking at yet another warm up with rain moving through the region. Yuck. But on the back side the situational looks much more favorable. I'm personally planning on making my first turns of the season next week, and I suggest you too clear your calendars. Starting on Tuesday night we're looking at nightly snowmaking windows! And the temperature profiles and durations look favorable enough that most mountains will likely get in the act. Below is the mid-week forecast at Sunday River at elevation.

    This initial mid-week window will be nights-only which may mean that some ski areas will sit this one out. But the cool streak looks to continue through next weekend. This could provide a long enough window for most of the traditional early-season players to open if they so wish. We're still a week out so this is subject to change, but it is showing up in the ensembles of all the global models. This is about as robust a signal as you'll see a week plus out. My skis are ready! Are yours?

  24. Weatherman
    I'm glad that the last storm is behind us. I wish I had a catchy name for it, but it sucked. I lost power at 8pm on Sunday and got in back at 8pm on Tuesday. Just to rub it in, my house was a smoke den last night because I lit the fireplace for heat (before the power came back on) but it wasn't quite cold enough to draft properly. Enough of my problems... we need some good news.
    Killington is making snow! But you probably already known that. They desperately need to put down some snow before the world cup, and they make a lot of money off early season stairway hiking with Joey from Jersey.
    Killington is nowhere near opening despite over 24 hours of "production" because conditions were marginal at best. They're blowing almost entirely air at the wet bulbs we have. And the other early-season player, Sunday River, is still cleaning up from a crippling wind and rain storm.
    The next snowmaking window comes Friday night into Saturday morning, but once again conditions are going to be marginal at best. Saturday night into Sunday may bring another marginal window, especially toward, Sunday River, but I would not count on it. Most ski areas will choose to sit out this weekend and save their money.

    Monday brings warmer weather, but that is where the predictability ends. Snowmaking temperatures may return for Monday night into Tuesday, or they may not. Midweek next week into the weekend could be boringly quiet with just some showers, or things could get interesting. What should I say in such circumstances?
    Recent weather has been anything but boring. Thousands across New England are still without power to prove it. But I'm tired of not seeing any snow in the forecast. If you promise not to judge me later, I'll get things started here. For your personal pleasure in the comfort of your own home.... this morning's GFS put out a bonafide November nor'easter with snow all the way down to Boston. Yummy!

    Next week's forecast is highly uncertain. We're approaching one of those windows with high unpredictability. Model solutions show no agreement. Buckle up! In the interim, I'm going to continue to pretend that snow is coming.
  25. Weatherman
    As promised, the last two days featured wet weather brought up by a strong southerly flow pumping up the subtropical moisture. I wish I could say that we're done with it, but the week ahead looks to bring very similar weather. The frontal boundary parked on top of the New England coastline isn't going to clear the region until Friday. Behind it dry weather should settle in for Saturday and the start of Sunday. However, by Sunday evening we'll see a return to the strong subtropical flow from the south bringing potentially damaging winds and strong downpours stretching through Monday.
    Give that it is five days out, it's no surprise that the exact details are fuzzy, but the pattern is clear as shown both in the GFS and ECMWF.

    Note the strong wind out of the south pumping subtropical moisture into New England. Don't get hung up on the timing or exact placement of the rain in the plot below, but note the potential for an additional several inches of heavy rain concentrated where convection trains into narrow bands.

    The heavy rain won't be the only story. The potential exists for damaging winds, especially along the coast. You'll find some alarmists noting near hurricane force sustained winds in some of today's model runs. It's too early to talk about that sort of magnitude. It's more likely you'll see something similar to the brisk southerly winds of the last two days. The strength of the upcoming system will depend on how well the tropical energy develops as it moves off the Florida coast. The intensity of these subtropical systems are typically poorly handled by operational models as their energy is derived from convection (thunderstorms) that are too small scale to resolve in the global models.
    The weather turns more seasonable heading into early November. The next window for snowmaking opens in the early morning Wednesday, November 1 and could last nightly through that weekend. As previously mentioned, humidity may continue to be an issue and snowmaking conditions look marginal. The operational GFS is currently showing a workable window, but this is uncertain. I suspect the cold here is greatly exaggerated.

    This window isn't evident in the ensemble mean, but I expect the ensemble to run a bit warm for a few different reasons. We're too far out to talk about it with any confidence, but I can't rule out the chance of a couple aggressive ski areas hosting some rock skiing that weekend if the forecast trends in their favor. It seems more likely that the snowmaking window begins in earnest sometime that weekend of November 4, and we see some early season openings early in the week of November 6-12.
    Just to show how touchy that Wednesday morning snowmaking windows is, here is the latest GFS ensemble temperature plot.

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