COMMENTARY
Good morning (or afternoon depending on when you see this) WHW readers! A quick review of the expectations and results of yesterday’s storm and some additional thoughts. This was a system that for many days was expected as a possibility “around the weekend” with many model forecasts just a handful of days before the event having it as a low pressure system tracking through the Great Lakes and a rain event here, in which the biggest challenge would have been whether or not the warm front was going to pass the entire region before the cold front arrived. It would have been too warm for anything other than rain to be involved in the precipitation shield. But many forecasters knew better that a solution such as that, or any other solution for that matter, that far in advance with recent and ongoing model performance issues was not something that you could look at and have any confidence in whatsoever. Hence, the forecasts (at least mine and probably many others) were written in vague terminology, which should always be used to reflect uncertainty. There is nothing wrong with uncertainty in the scientific process. If not for it, we’d lose our desire to learn and improve. As we got closer to the event, and it become more and more obvious that the track and development of the low center, and precise details around both, would leave the tiniest margin for error for making or breaking our forecasts on it, I can speak for myself and others when I say the challenge become the real deal. One of my colleagues noted how a 1 or 2 degree difference could literally make the difference between an inch of snow and over a half foot of snow, and the 1 or 2 degree difference was not just the temperature at the surface, but the temperature throughout the entire depth of the storm from surface to top of clouds. That one small aspect, before we include all other aspects, went very much into determining a much bigger outcome, as noted by a comment on yesterday’s blog, the final snow numbers. This, not necessarily through any fault of their own, is what the general public is looking at. Joe Public doesn’t really care what my temperature forecast is for 850 millibars, if the wind direction is from direction 20 or 330 (yes it makes a difference), or any of that. Joe Public wants to know how much snow he has to shovel, or plow. And I get that. Unless one is a weather geek, they’re not looking at forecasts and listening to media for discussions of a storm’s dynamics, they just want to know what, when, and how much. I assure you every forecaster out there gave it their all in trying to figure this one out. Some forecasts worked out OK, some did not. Some worked out great in some areas and poorly in others. That’s the nature of what we do, and this was a prime example of that. We saw a lot of good forecasts for nearly every detail of this system, from its evolution and its track, to its precipitation timing and marginal temperature profile, snow being dependent on precipitation intensity in bands we had to try to forecast development of, and intensity of, and worry if these bands would even form enough at all to do what we expected. How ironic that, in many (not all) areas, that the only aspect of the forecast that didn’t work out as well was the ONE that most people were most interested in. Most of them didn’t care that the 1 to 2 1/2 inches of rain forecast before any mixing and changing did indeed occur, and as a result gave our drought yet another gut punch. That’s some good news. Ah, so Joe Public may have any number of reactions. He may be posting on social media this morning that “they got it wrong again! what a great job where you can be wrong and still get paid” (old joke, heard it before), or he may be a snow lover who is just angry that only a slushy inch or two of snow fell when he was expecting 6 and a perfect forecast, or he may be happy because even though he doesn’t mind some December snow, that we didn’t have enough to bring down a hundred more trees in his city putting most people in the dark for a day or longer, and causing more damage. People have their reactions, and that’s fine. But no matter what we expect and how we react, I’d like to remind all of them for a moment to remember what goes into making these predictions, and how easily they can go awry, and how often they don’t compared to how often they do. I say this, not because I think more folks than usual are bent out of shape about the snow aspect of this system, but because it’s important for us to try to understand what goes into doing a job, and I don’t mean just weather forecasting. This can be applied to any position, and a couple that come to mind immediately are first responders, which goes without saying, and utility workers. Yes, it sucks when the power is out for any length of time, but understanding why it may take some time for them to get to the line down the street that was cut by one branch, while there are hundreds and maybe even thousands of others just like that, and that yours can’t always be first, is very important. The set-up for doing these jobs isn’t perfect, and will never be perfect, but people in these do the best they can. The same with weather, really. Forecasting is never going to be something we ever achieve perfection in, but doing the best you can should never be thought of as failure. Aspects of a forecast may fail sometimes, but a strong effort is always a success.
DAYS 1-5 (DECEMBER 6-10)
Low pressure exits via the Canadian Maritime Provinces today, leaving in its wake a blustery and cold day with passing clouds and a remote chance of a few snow flakes or rain drops falling from some of these clouds. With winds still gusty, keep an eye out for loose branches that may still be caught in trees. The damage from yesterday’s storm was not too bad, but older trees still saw some broken branches and limbs from wind and in some cases wet snow. Also, temperatures having slipped into the upper 20s to very low 30s in many areas north and west of Boston early this morning has caused some ice patches to form in ground that was just wet last evening. This should melt and dry off during the day today as temperatures rise above freezing and wind and dry air work on the ground. But where some melting causes more puddles, watch for re-freezing and additional ice patches tonight. Winds diminish tonight as the Canadian low moves away. Our attention then turns to 2 things, an offshore storm developing later Monday and passing southeast of New England early Tuesday. This system is fully expected to be offshore for enough to avoid any significant impact, but its circulation will be large enough to create a northeast to north wind over Cape Cod that may carry some light showers of rain and/or snow across that area on Tuesday. In addition, a disturbance breaking off from a trough to our west will initiate some cloudiness for us here on Monday, and maybe enough for some snow showers Monday night and early Tuesday before the energy is absorbed by the offshore storm. At midweek, expect a dry and chilly Wednesday, but a disturbance moving rapidly southeastward may bring a few snow showers to the region Wednesday night and early Thursday, with a bit of a reinforcing shot of seasonably chilly air following.
TODAY: Cloud/sun mix. Slight chance of a passing sprinkle of rain or flurry of snow. Highs 35-42. Wind NW 15-25 MPH and gusty, diminishing late day.
TONIGHT: Mostly clear. Lows 18-25. Wind NW diminishing to under 10 MPH.
MONDAY: Partly to mostly cloudy. Highs 31-38. Wind variable up to 10 MPH.
MONDAY NIGHT: Mostly cloudy. Chance of snow showers. Lows 28-35. Wind NE to N 5-15 MPH except 15-25 MPH Cape Cod.
TUESDAY: Mostly cloudy to partly sunny. Chance of snow or rain showers Cape Cod. Highs 35-42. Wind N 10-20 MPH, higher gusts especially Cape Cod.
TUESDAY NIGHT: Mostly clear. Lows 20-27. Wind N to NW 5-15 MPH.
WEDNESDAY: Mostly sunny to partly cloudy. Highs 36-43. Wind variable up to 10 MPH.
WEDNESDAY NIGHT: Variably cloudy. Chance of snow showers. Lows 25-32. Wind NW 5-15 MPH.
THURSDAY: Partly sunny. Chance of snow showers in the morning. Highs 35-42. Wind NW 10-20 MPH.
DAYS 6-10 (DECEMBER 11-15)
High pressure brings fair and pleasant weather for December 11. The next low pressure system is set to impact the region on the December 12-13 weekend, but the track, timing, and intensity of the system is somewhat uncertain. The early idea is that low pressure may track through the Great Lakes and northern New England or nearby Canada, with a warm front trying to move through followed by a cold front. Frontal positions and timing in this scenario would be uncertain this far in advance, so for now just going to forecast a chance of some precipitation at times for the weekend. Fair, seasonably cold weather should follow this.
DAYS 11-15 (DECEMBER 16-20)
Watching December 16-18 as a window for potential storm threat (rain/mix/snow – still too early to know).