9:12AM<\/p>\n
DAYS 1-5 (DECEMBER 9-13)
\nHere comes the first widespread snow event to include most of the region, and it will be the result of a wave of low pressure moving along a cold front offshore. This wave of low pressure is wave #2 of 2 that we’d been eyeing, with #1 having gone by overnight with a few raindrops reaching Nantucket during the night. But that rain is important. It tells us that it is warm enough for rain somewhere, and without a ton of cold air draining in it also tells us that it will remain warm enough for rain somewhere, so this does not become a measurable snow event for all. But we’ll get back to that in a moment. Just to go back briefly and touch upon why this and many forecasts leading to an event are not so clear cut. We’ve been eyeing a batch of energy diving out of Canada and into the upper Midwest and Great Lakes. The timing of this was key to whether or not one of these offshore waves would evolve more and come close enough to deliver precipitation to everyone. One theory for the difficulty in timing this a few days ago outside of normal model uncertainty is the fact that there is less data coming out of Alaska available for models, i.e., fewer upper air soundings. How much of a roll this may have played is not really known, but it will be interesting to see if similar situations occur going forward. Also, as a little fun fact, it seems that December 9 and 17 have become favorable dates for snow over the years. Looking back in history, and I won’t list a bunch of dates here at this point, there have been quite a few events of one type of another on these 2 dates. Today will be no exception. Once upon a time I thought today’s event would occur but would be placed far enough northwest for a lot of the region to have rain. This turned out to be a medium range forecasting error. So today we will once again attempt to foretell the future with minimal errors! Basically the forecast from my perspective is not really changed since yesterday so there is not much to say other than recapping we’ll have precipitation expanding across the region today, first with just spotty areas of very light snow except rain Cape Cod during this morning, becoming more steady from south to north later in the morning through midday and peaking during the afternoon and evening before ending west to east tonight. The rain\/snow line will start out around Cape Cod and progress west northwest to at least to a Plymouth \/ New Bedford line. It will also bend up to include parts of Cape Ann where a northerly wind comes off a warmer ocean surface. It will likely expand to include most of the South Shore and possibly mix right up to near Boston. As everything winds down this rain\/snow line will head back to the east. For road impact, look for moderate impact due to snow especially this afternoon into tonight where it is all snow, and less impact with mainly wet roads from the South Shore through Cape Cod. Overnight and early Sunday look for some icy areas on untreated surfaces. Looking ahead, a disturbance may produce a few snow showers Sunday and a lingering trough will keep some cloudiness around and maybe even a few additional flurries on Monday. The early call on the next system is a clipper that tracks over southern New England and redevelops to the east but too far north to give a significant snow event to the WHW forecast area. Still more details to iron out on this. Time for forecast details…
\nTODAY: Overcast. Spotty light snow except rain Cape Cod this morning. Steadier precipitation advancing northward late morning and midday mainly as snow except rain Cape Cod and a change from snow to rain into the South Shore towns of MA as well as Cape Ann MA. Highs 30-40, coldest in north central MA and southwestern NH and mildest South Shore to Cape Cod MA. Wind light N.
\nTONIGHT: Overcast evening with snow except rain South Shore to Cape Cod, then breaking clouds with snow tapering off west to east and rain changing to snow before ending South Shore to Cape Cod. Lows 25-32. Wind N to NW 5-15 MPH. Snow accumulation for this event: Under 1 inch Cape Cod, 1-3 inches Cape Ann and MA South Shore, 3-6 inches elsewhere.
\nSUNDAY: Variably cloudy. Scattered snow showers. Highs 32-39. Wind NW 10-20 MPH with higher gusts.
\nSUNDAY NIGHT: Partly cloudy. Lows 22-29. Wind NW 10-20 MPH with higher gusts, diminishing overnight.
\nMONDAY: Variably cloudy. Slight chance of snow showers. Highs 33-40. Wind W up to 10 MPH.
\nTUESDAY: Cloudy. AM snow to mix\/rain. PM rain showers. Evening snow showers. Lows in the 20s. Highs from the upper 30s to lower 40s.
\nWEDNESDAY: Partly cloudy and windy. Lows in the 10s. Highs in the 20s.<\/p>\n
DAYS 6-10 (DECEMBER 14-18)
\nFair and very cold December 14. Next clipper brings a risk of snow or snow showers December 15. Fair but not as cold over the weekend of December 16-17 and then another clipper may follow that with a rain\/snow risk. Timing obviously uncertain this far in advance.<\/p>\n
DAYS 11-15 (DECEMBER 19-23)
\nOverall temperatures below normal with a couple opportunities for precipitation, favoring snow or snow showers, from passing clippers.<\/p>\n","protected":false},"excerpt":{"rendered":"
9:12AM DAYS 1-5 (DECEMBER 9-13) Here comes the first widespread snow event to include most of the region, and it will be the result of a wave of low pressure moving along a cold front offshore. This wave of low pressure is wave #2 of 2 that we’d been eyeing, with #1 having gone by … Continue reading Saturday Forecast<\/span>