COMMENTARY
You may have heard many things on social media the last few days ranging from “sneaky snow for today” based on someone grabbing one HRRR model run that was poorly initialized, or getting caught up in the hype of a SSW (Sudden Stratospheric Warming) event that was “supposed to flip our pattern to full on winter with relentless cold and snow” but these are words of hype-masters and wish-casters who don’t really do this for the reason of actually informing the followers, but instead garnering clicks and shares, and/or getting the thrill of being “the one to break the news” even if it’s far-fetched. That said, there is an ongoing event that disrupts the Polar Vortex, which while not a frequent occurrence is also not something that would be a surprise, and also does not guarantee any single area sees an abundance of any specific kind of weather either – at least until we get a chance to properly scientifically examine the evolution of the event and the pattern that results, the details of it, and the duration of it. As a forecaster, that’s something I’ll be doing in proper timing. In other words, I’m not going to tell you that we have a super high chance of the snowiest December in years because I simply don’t know about that yet. We just passed the half way point of November. And while “meteorlogical winter” is just under 2 weeks from its start, actual winter is still over a month away from arriving. We’re in late autumn, not winter, right now. One event, one pattern change, one thing at a time. Looking ahead is perfectly fine – that’s why it’s called “forecasting”, but apply the science that error increases as time beyond the initial does. You’ll do better. If the consumer realizes this is a fact of the science of meteorology, they’ll do better too.
DAYS 1-5 (NOVEMBER 19-23)
The last few days featured a lot of wind and chilly air. Today, we still have chilly air, but a much more tranquil day as a small area of high pressure has built over our region and relaxed the lower atmosphere – i.e., taken away the pressure gradient that was present between the approach of this high pressure area and the very slow departure of an expansive area of low pressure spinning about in Atlantic Canada. You will notice today that we will have a veil of high cloudiness moving across the southern sky, even some mid level clouds underneath the higher deck especially closer to the South Coast, limiting the sun even more than just the filtering the higher clouds do to it further north. This is from a small low pressure system being shunted just south of our region from what remains of the blocking pattern that was in place for a while. A high pressure area that had been parked over Greenland now drifts eastward on a journey toward northwestern Europe and this relaxes the block and opens the door for a storm track that moves through the Great Lakes into eastern Canada more easily. This more progressive pattern means several upcoming changes to our weather and things to keep track of as we head through the rest of this week (and next week – Thanksgiving Week – which I’ll talk about in the next section). We’ll keep fair weather Thursday as high pressure hangs on, although an upper disturbance passing by to our south will again produce some cloudiness in the region, limiting the sunshine. The next thing I’ve been watching is how the late-week unsettled weather threat was going to play out. After seeing a variety of model solutions and watching trends here, how I think it plays out is that low pressure travels through the Great Lakes then down the St. Lawrence Valley late Friday and Friday night, dragging its cold front across our region. Milder air ahead of this system means that any showers that are triggered by the front would be in the form of rain. Additionally, as the front passes, a weak wave of low pressure will get going on it and pass just to our south, and this can toss a short-duration shield of light rainfall into the South Coast region, maybe up as far north as the MA South Shore in the pre-dawn hours of Saturday. The quick movement of this system means that any wet weather threat is gone by about sunrise Saturday, and other than a deck of clouds “delaying sunrise” aka making the sun not visible for a while as it rises, it looks like a dry day. We will see it turn a bit cooler than Friday along with an increasing breeze as the day goes on, but not as windy or cold as the days early this week were. A bubble of high pressure will scoot just south of us on Sunday, keeping our weather fair and seasonably cool for late November. If you like to get a jump on decorating outside for the holidays, this coming weekend looks ideal for doing just that.
TODAY: Sunshine will be brightest in southern NH / northern MA, filtered to dimmed further to the south by some high and patchy middle cloudiness. Highs 46-53. Wind W 5-15 MPH diminishing and becoming variable under 10 MPH.
TONIGHT: Variably cloudy. Lows 25-32. Wind calm.
THURSDAY: Clouds limit the sun. Highs 47-54. Wind variable up to 10 MPH.
THURSDAY NIGHT: Partly to mostly cloudy. Lows 33-40. Wind SW 5-15 MPH.
FRIDAY: Variably cloudy. Highs 47-54. Wind SW 5-15 MPH.
FRIDAY NIGHT: Mostly cloudy. A rain shower possible mainly north of I-90. A period of rain pre-dawn South Coast to possibly MA South Shore. Lows 38-45. Wind SW 5-15 MPH shifting to NW.
SATURDAY: Limited sun early, then a sun/cloud mix. Highs 45-52. Wind NW increasing to 10-20 MPH.
SATURDAY NIGHT: Partly cloudy. Lows 28-35. Wind W up to 10 MPH.
SUNDAY: Partly cloudy. Highs 47-54. Wind W 5-15 MPH.
DAYS 6-10 (NOVEMBER 24-28)
There are potential disturbances to bring at least marginally unsettled weather about every other day during Thanksgiving Week (holiday is November 27). Watching November 24, 26, 28 for best unsettled weather chances, with some up and down temperatures (averaging near to slightly above normal for the period) with the quick-changes as well. Deterministic details are impossible this far in advance with this type of pattern. Obviously much fine-tuning to come.
DAYS 11-15 (NOVEMBER 29 – DECEMBER 3)
A more significant shot of cold air is possible to end November – timing and details are TBD. Leaning chilly/dry for the start of December but with low confidence. Medium range guidance shows a comical variety of outcomes here, so this is just based on my overall feel of the larger scale set-up I think we will have at the time.