csnavywx

Looks reasonable to me. Better to hedge lower until some of the mesoscale details can be worked out.

Our snowfall down here is going to be completely dependent on how quickly and cleanly the coastal low can spin up. Strong CAA in the PBL will help switch p-types over eventually on Wed. morning, but in order to get decent totals, we're going to have to get into the CCB and deformation zone snows. That's certainly possible in a 12Z Euro or 18Z GFS type setup where the surface low rapidly develops and the mid-level low quickly closes off overhead or just south and allows decently strong lift gets going in the DGZ. However, with marginal surface temps and March sun, we're going to need the rates to produce. If that doesn't happen, it'll be a grass and car topper.

The last two years have seen some pretty stunning winter anomalies. The negative feedback from ice thickness growth hasn't really shown up as a result. There's a recent paper that's somewhat related to this by Cvijanovic and Santer (https://www.nature.com/articles/s41467-017-01907-4), Though the abstract focuses on California rainfall, it shows important global changes as well. It even goes into Antarctic sea ice and responses to that as well. TLDR is while the Antarctic response to AGW has been slow (outside the oceans), the Arctic has not, and the downstream effects as a result have been fairly large. There's an opportunity (as outlined in the paper) for future Antarctic sea ice losses to dampen the Arctic-to-tropical response, but since the Antarctic is (a) slower to react and (b) has less ice to lose overall, we should probably expect more of the same in the future, if not at the same magnitude every year.

Solid storm all around. This storm heralds a pattern change (as the big ones often do) to warmer weather in a few days. The warm-up looks fairly brief, however as the strong -AO pattern looks to rebuild out mid-month. Should bring more chances late this month.

Estimated 6" here as best as I can tell, maybe a bit more, maybe a bit less. Had a solid 3" when I went to bed at 3:00 am before it started blowing around a ton. Have 1-2' snow drifts everywhere. Got fairly close to blizzard conditions at NHK at times (a few obs near gale force sustained and 1/4 mi vis.). Still getting light accumulating snow (occasionally moderate) with good flake size. All dendrites.

2.5" here. Steady moderate to occasionally heavy snow. Getting increasingly wind-whipped and blown. Small to medium sized aggregates (mostly dendrites). Low looks to be tied almost entirely to the coastal front, putting it on the far western side of the envelope. Should keep the snow around longer since it will take longer for the northern stream shortwave to kick this thing out to sea.

Getting a few larger aggregates. Snow is mainly dendrites and stellar plates, with a few columns mixed in. Looks like most of the lift is in the DGZ tonight, which should result in some good snow growth, albeit dry, given the low column temps.

Getting blasted under this new f-gen band. <1/4sm. Small flakes, but tons of them. It's headed up your way, Prince.

Lift associated with coastal front is headed in to the eastern shore. Should be seeing some localized rippage with that.

Blizzard warnings out up to SBY and OC.

Coastal front looks to get going this evening. Could really cash in with that on the eastern shore.

Sorry, meant to pipe in here earlier. Looking decent for some banding to set up somewhere over the central or southern Bay out towards the eastern shore. Could be a couple of strong or intense bands as the low bombs off of OBX and moves NNE then NE. Placement is sketchy, since there's some uncertainty, but I do think there will be a very sharp cutoff on the W/NW side due to dry advection and mesoscale subsidence away from the better (focused) dynamics near the bay shores and eastern MD shore. Looking like a LFI-SBY or ORF-DOV special atm. If the latest trends in the upper levels on the GFS and NAM are any indication, then the max may be closer to LFI-SBY line. They're safely away from any possible mixing and close enough to get into some of the more intense frontogenesis and mid-level WAA.

I wouldn't expect miracles. Cloud top temps are still marginal, just somewhat better than they are now, which could be cold enough for some moderate snow.

Wouldn't get too discouraged just yet. We should get a decent parting shot from the deformation zone as the low deepens and moves northeast further offshore.

Deformation zone should swing through and drop another inch or two, but barring some good mesoscale banding, that's gonna be about it, most likely. Poor snow growth outside those bands are going to keep accumulations down.

Probably a mixture of snow grains and ice pellets (frozen drizzle in this case).

Definitely. Had 3" here at one point. Melting, light mixing and compaction brought that down a bit. Maybe an inch and a half left close to the shoreline.

Winter temperatures DO matter -- to an extent. My personal favorite is freezing degree days, but you could use other measures just as well. I use FDDs because of the easy relationship to ice thickening. Ice grows quickly at first, but growth slows as it insulates the underlying water from the atmosphere and slows heat exchange. This principle works in reverse: a degree or two of warming doesn't matter all that much at first because the loss in spring thickness is initially small. However, further warming causes increasingly larger spring thickness losses as the relationship of FDD anomalies to ice thickness is exponential. When you start dropping below 2500-3000 FDDs, the spring thickness loss rapidly drives upward. The critical point (based on PIOMAS thickness experiments) seems to be around 1.6m. Below that thickness, ice doesn't survive the summer in the basin, almost no matter how favorable the weather is. Add 2C to last winter's ridiculously warm winter and place a 2007 or 2012 style summer on top of that and you've pretty much got a blue Arctic Ocean at the end of the summer. That kind of scenario is probably 15 years away still.

Translating that into Arctic temps might yield a 1C cooling. This is highly speculative, of course, and depends on the timing and size of an eruption (if any).

VEI 5/6 eruptions in that portion of the globe are particularly effective in lowering global temperature. The effect would be on the order of 0.2-0.3C, provided the same eruption size. A weaker eruption might be closer to 0.1C, and a VEI6 may get closer to 0.4C. Peak cooling is generally 12-20 months after an eruption of that magnitude, though the tail can last up to 4-5 years. There is typically a rebound effect above the baseline a few years after a major eruption as masked radiative forcing emerges over a cooled surface.

Arctic (66+N). Last winter will be tough to beat, as the Oct/Nov temps were extremely warm. Who knows, though.

As we move into the re-freeze, the summer pattern is fading and is being replaced by a now-familiar sight: strong to extreme blocking near the Kara/Barents and Scandinavia.

Yeah, pretty remarkable warming in that region. Also see: https://www.ncbi.nlm.nih.gov/pubmed/28386025 I'm trying to dig up some of the figures from that, but if I recall (from reading it earlier in the year) the shoaling magnitudes were pretty remarkable. On average, the water layer had shoaled halfway to the surface on the order of a decade or so and is steadily progressing eastward. It was part of the reason (along with the warm weather) why it took so long for that ice to freeze up last fall/winter.

While I don't think we'll melt out before 2030, I really think it's unlikely we recover to pre-2007. Part of that is the consistent loss of ice in the Beaufort Gyre region, which has flipped from being a system which recirculates MYI from season to season to a system that effectively destroys it (this year included) due to melt before it can be recirculated. Another is the remarkable amount of shoaling of warmer Atlantic Water (AW) on the Eurasian side of the basin. The forcing from this oceanic input is substantial. These factors alone are enough to prevent a MYI recovery. Without a sustained recovery in MYI, a FYI dominated basin will always be susceptible to summer melt-out, even in somewhat cooler-than-average summers. The downward trend in April volume (which has a fairly large correlation of about .4-.5 to Sept. volume) has not stopped or slowed down. Unless that changes, this signal will eventually overwhelm any temporary gains due to cooler summer weather in the long run. Bottom line -- predicting imminent doom or recovery in the pack at this point kinda leaves the predictor as a hostage to fortune.

Can gradually see the late season ice pack of the next decade taking shape this time of year. 2016 and this year are good examples with a solid compacted half moon-shaped slab up against the CAA where the remaining MYI is located and an arc of weakened FYI from the Beaufort side right across the pole. A warmer summer would have melted that arc and left the MYI in place. Weather gets much more hostile over the next few days, which will open the Pacific bite up even more, but it's much too late in the season for any of the compacted FYI/MYI to be melted away. It could definitely make a run at tying last year or 2007, though and leave a lot of scattered patches at the minimum. As we saw last year, that tends to re-freeze pretty quickly in late Sep and Oct. Just not quite warm enough to maintain open ocean that far north yet.