The weather report for Maui and why I think that matters

We got a nice dose of snow and a little sleet over the last two days but I'll start this post by talking about snow in a more exotic location and why I think the cause of that snow has played such a significant (in my opinion) role in dictating the larger scale pattern across North America this month. I am sure some have seen this as a footnote in the news headlines recently but in case you didn't, the island of Maui in Hawaii received a historic snow and there was an accumulation recorded at a historically low elevation.

Maui Snowfall

Snow does fall routinely in Hawaii, mainly on the Big Island where the 14,000 foot Mauna Kea and Mauna Loa volcanic mountains are located, but Maui rarely sees snow since its highest elevations are lower. It takes a rather special set of circumstances for the jet stream to support such an outcome, but it happened because of an unusually strong area of storminess that undercut a broad area of Mid-Latitude ridging in the jet stream over the Pacific in recent days. Why does any of this matter ? Well, the weather in the Pacific certainly matters and the storminess that occurred at those very low latitudes caused the MJO to nearly go off the predictive map. The MJO which is used to explain the phases of convective activity in the low-latitude Pacific, has become popular in recent years for predicting winter weather over North America. The various phases can certainly greatly impact the strength of the mid-latitude Pacific jet stream. Unfortunately the MJO is like a knuckle-ball pitcher in baseball. Looks like you can hit monster home runs forecasting the weather a few weeks out using the MJO but it hardly ever works. MJO phases are often much harder to predict than they appear and then when you can accurately predict it, the outcome in North America is entirely different. That's what happened thanks largely to the storminess in Hawaii. The Pacific took on a look, based on some of the measurable charts, as if it would support widespread cold weather across lower North America but the storminess at Hawaii's latitude was so unusual that the pattern ended up just supporting cold across western North America and we thus have a jet stream regime that is almost locked in this "negative-PNA", "cold west/warm east" structure.

Wow that was way too long but nonetheless important. Thanks for bearing with me.

Our recent snow has allowed us to move somewhat out of those "frozen hellscape" conditions but the pattern which has dominated for February is going to continue through most of the rest of the month and send some challenging weather situations in our direction. That said, we are not in the worst of shape. The good news regarding the weekend weather still holds. After somewhat seasonable Thursday, milder temperatures will arrive with a northeastward moving weather system Friday. This storm will take a horrendous track into Quebec but is moving quickly enough, and isn't strong enough to bring enough mild weather to create problems on the mountain. Instead we will have clouds and a period of somewhat wetter snowfall on the mountain beginning in the mid-morning hours Friday with mixed rain and snow in valley locations. This isn't a dream situation but it's a lot better than some of the alternatives advertised on some of the forecast simulations 5 days ago. Above 2000 feet, I think its 3-6 inches of snow is the most likely outcome before drier and colder air envelops us later Friday evening.

The holiday weekend is looking very quiet now. Some flurries are possible Saturday but no significant snowfall is expected. Temperatures will be generally seasonable with readings in the single digits during the early AM and 20's during the afternoons. There are two systems in the ensuing holiday week that we will be watching. The smaller, first system would impact the east coast Monday and my guess is that precipitation and snowfall remains to our south. The second system in the Wednesday to Thursday time frame of next week has a better shot of bringing the action our way. Now by later next week, the ridge in the jet stream across the southeast is expected to once again become very formidable. The cause of this can be traced back to that ridiculous tangent I took you all down to open the blog post. We are in a position to fend off this push of very mild air but it's no certainty we can keep precipitation from changing to something other than snow. In addition, it appears likely that we will have to contend with a round of above-freezing temperatures sometime around the last weekend of February.

Beyond that, some disagreement has emerged in the forecast data. There are hints that the negative PNA regime that has dogged us this month, but allowed it to just dump on the west, will break down and allow for a period of colder weather around the turn of the month. Other data suggests the pattern might linger into early March. Overall it isn't terrible since there is enough arctic cold across North America collectively to keep interior New England in the game, but to procure another true epic period of snowfall, the strong negative PNA regime will need to break down somewhat.