C-19 Chat Post – December 14 2020

DAYS 1-5 (DECEMBER 13-17)

A temperature / dew point match and calm wind means that many wake up to a dense fog this morning, except portions of the South Coast where the temperatures are a little higher and there are only patchy areas of fog. Those areas are in the warm sector, while areas with the more widespread fog in place remained in the cooler air – i.e., the warm front never got through there. A frontal boundary from the west pushes through the region this morning and introduces a drier air mass to the region, which will be evident as fog dissipates and the wind picks up from the west during the day. But this air mass is not really that cold at all so it will be a nice day, temperature-wise. For areas in the cool air still, we call this frontal passage a “warm occlusion”, because the air behind the front from the west is milder than the air that was north of the warm front that did not make it through those areas. South of the warm front, areas that are in the warm sector will have that front pass as a cold front, though the air behind it will be milder as it passes those areas due to time-of-day, diurnal warming. Colder air will gradually filter into the region during tonight and we should have just enough clear sky to at least get a chance to view the peak of the Geminid meteor shower. This meteor shower can produce up to about 60 meteors per hour if you are viewing with clear sky and away from light pollution, so in our area the rate of visible meteors will likely be under that with at least partial cloud cover. The clouds come quickly back in overnight and into Monday while on the frontal boundary just gone by, a wave of low pressure will come rippling along rather quickly to the northeast. This low pressure area will come close enough to bring a period of snow and rain to the region during Monday, although it will be a fairly short-duration event that is not too heavy. It does have the potential to produce some minor accumulation of snow, and based on the track and marginal temperature profile expected, the greatest chance to see this accumulation will be along the I-95 and I-90 areas in general. This system exits Monday evening and a reinforcing cold front slides rather quietly through the region, but its impact will become rather noticeable as the cold air behind it arrives during Tuesday as high pressure to the north brings fair weather. This cold air is going to be around for a while, and plays a role in our next storm threat, currently timed for Wednesday night and Thursday. This will take place as low pressure tracks northeastward from lower Mississippi Valley toward the Ohio Valley, then quickly redevelops near the Mid Atlantic Coast, tracking just south of New England. The precise track of this low pressure area and the precipitation distribution to its north will determine how much snow falls in our area. With this threat at the end of our day 4 and well into our day 5 forecast, it’s far too soon to discuss specific snowfall amounts, but not too soon to say the system has the potential to produce a significant snowfall for at least a portion of the region. As always, this will be fine-tuned through the meteorological process as we get closer to the event, and you can see my thoughts in the daily comments section and of course each morning update.

TODAY: Widespread fog especially Boston area west and north to start, gradually dissipating toward midday. Mostly cloudy to partly sunny. Highs 55-62. Wind SW to W increasing to 5-15 MPH, gusts up to 25 MPH.

TONIGHT: Partly cloudy. Lows 28-35. Wind NW 5-15 MPH.

MONDAY: Mostly cloudy. A period of snow/mix/rain, but favoring snow with accumulations of a coating to 2 inches. Highs 32-39. Wind N to NW 5-15 MPH.

MONDAY NIGHT: Clearing. Lows 20-27. Wind NW 5-15 MPH.

TUESDAY: Mostly sunny. Highs 30-37. Wind N 5-15 MPH.

TUESDAY NIGHT: Mostly clear. Lows 17-24. Wind N under 10 MPH.

WEDNESDAY: Sun followed by increasing clouds. Highs 28-35 Wind N up to 10 MPH.

WEDNESDAY NIGHT: Thickening overcast. Snow arriving. Lows 18-25. Wind N to NE 5-15 MPH.

THURSDAY: Overcast with snow, ending late. Significant snow accumulation possible. Highs 23-30. Wind NE to N 10-20 MPH, higher gusts possible.

DAYS 6-10 (DECEMBER 18-22)

Dry, cold weather expected behind storm with Canadian high pressure December 18-19. Next unsettled weather threat comes later on December 20 with rain/mix/snow possible, followed by a return to dry weather December 21-22 and a shot of seasonably chilly air.

DAYS 11-15 (DECEMBER 23-27)

Pattern still looks somewhat active, a little milder to start, then colder again. Can’t rule out a couple rain/mix/snow threats which I’ll bring into focus as we get closer to this time period.

C-19 Chat Post – December 13 2020

DAYS 1-5 (DECEMBER 12-16)

We’ve an active weather pattern on our hands and a few other things to talk about too! We start our weekend with the approach of a warm front which will lead to thickening cloud cover after much of the region starts the day with fog. Areas of rain will follow the thickening cloud cover, arriving from southwest to northeast later this morning through the afternoon hours. While it won’t likely rain the entire time, a few of the episodes may be moderate. The low pressure area parenting this warm front will track northwest of New England tonight and north of the region Sunday. The warm front will probably not get through the entire area, with northern MA and southern NH staying coolest through Saturday night. The cold front trailing this low pressure area will cross the region during Sunday morning (as a warm occlusion in areas that the warm front has not passed). This front may produce a few rain showers, but the balance of the day is expected to be rain-free and rather mild by December standards. A secondary cold front will sweep across the region behind the departing low from northwest to southeast Sunday night, delivering a batch of colder air to the region. Let’s hope for some clear sky Sunday evening as we experience the peak evening of the Geminid meteor shower, with up to 60 meteors per hour visible away from city lights. If the sky is clear enough, look into the east northeast sky between 8PM and 11PM for peak activity, radiating out from the left side of the Gemini Constellation. During Monday, a wave of low pressure will be moving rapidly east northeastward and will pass southeast of our area. Model guidance has trended a little further north with this system, and it may indeed have some impact on the region Monday, spreading its precipitation shield at the very least into southeastern portions of the forecast area. Will forecast a minor snow accumulation event for this and make adjustments if necessary on tomorrow morning’s blog update. Temperatures will be marginal for this event and rain will likely be involved as well, at least for parts of the region, if the precipitation shield does indeed make it far enough north. Regardless of the details, behind this system will come colder air as high pressure builds across eastern Canada. We’ll have dry weather Tuesday and at least into Wednesday as we eye the approach of another storm system that threatens the region with snow as early as Wednesday afternoon…

TODAY: Areas of fog. Becoming Thickening overcast. Periods of rain midday on. Highs 40-47 southern NH northern MA, 48-55 to the south. Wind N-NE 5-15 MPH southern NH and northern MA, variable to SE 5-15 MPH elsewhere.

TONIGHT: Overcast with areas of fog and occasional rain in the evening. Mostly cloudy with continued areas of fog and rain showers overnight. Lows 37-44 southern NH and northern MA, 45-52 elsewhere. Wind NE up to 10 MPH in southern NH and northern MA, variable to S 5-15 MPH to the south.

SUNDAY: Mostly cloudy to partly sunny. Chance of rain showers early. Highs 53-60. Wind SW 5-15 MPH, gusts up to 25 MPH.

SUNDAY NIGHT: Partly cloudy. Lows 28-35. Wind NW 5-15 MPH.

MONDAY: Cloudy. Chance of rain and/or snow, favoring southeastern MA, eastern CT, and RI where accumulations of up to a few inches of snow are possible. Highs 35-42. Wind N 5-15 MPH.

MONDAY NIGHT: Clearing. Lows 20-27. Wind NW 5-15 MPH.

TUESDAY: Mostly sunny. Highs 30-37. Wind N 5-15 MPH.

TUESDAY NIGHT: Mostly clear. Lows 17-24. Wind N under 10 MPH.

WEDNESDAY: Increasing clouds. Chance of snow by late day or at night. Highs 28-35. Wind NE 5-15 MPH.

DAYS 6-10 (DECEMBER 17-21)

Potential snow event into December 17, details to be determined by storm track. Dry, cold weather December 18-19. Next threat of precipitation comes later December 20 into December 21.

DAYS 11-15 (DECEMBER 22-26)

Minor precipitation event possible around the middle of the period, otherwise a quieter and seasonable pattern seems likely.

C-19 Chat Post – December 12 2020

DAYS 1-5 (DECEMBER 10-14)

High pressure delivers a nice December day today. The weekend will turn out somewhat unsettled as low pressure cuts across the eastern Great Lakes then down the St. Lawrence Valley, its warm front never really making much progress through the region during Saturday, when some periods of wet weather will occur. Although an partially occluded front / cold front will pass by during Sunday, that day itself may not be all that bad, with limited rain shower activity confined mainly to the early part of the day, and fairly mild air for December. Colder air will filter in early next week. Monday, low pressure passes south of the region and may be close enough to bring some light precipitation at least to southern areas while a low pressure trough may bring a few snow showers to northern locations. Dry weather is expected Tuesday with high pressure extending into the region from eastern Canada.

TODAY: Sun and high clouds. Highs 40-47. Wind SW up to 10 MPH.

FRIDAY NIGHT: Increasing clouds. Lows 30-37. Wind SE under 10 MPH.

SATURDAY: Mostly cloudy. Chance of light rain, mainly in the afternoon. Highs 45-52 except 38-45 in northern MA and southern NH Wind SE up to 10 MPH.

SATURDAY NIGHT: Cloudy. Spotty light rain except possible pockets of freezing rain southern NH and northern MA. Lows 31-38. Winds NE under 10 MPH.

SUNDAY: Variably cloudy. Rain showers likely, mainly during the morning. Highs 46-53. Wind variable 5-15 MPH becoming W.

SUNDAY NIGHT: Variably cloudy. Lows 28-35. Wind W 5-15 MPH.

MONDAY: Mostly cloudy. Chance of light snow/mix/rain favoring South Coast. Chance of passing snow showers southern NH and northern MA. Highs 35-42. Wind variable 5-15 MPH becoming NW 10-20 MPH.

MONDAY NIGHT: Partly cloudy. Chance of snow showers early. Lows 22-29. Wind N 5-15 MPH.

TUESDAY: Mostly sunny. Highs 33-40. Wind N to NE 5-15 MPH.

DAYS 6-10 (DECEMBER 16-20)

Storm threat (rain/mix/snow) December 16-17 with details depending on track of low pressure. Colder/dry December 18-19. Risk of snow and rain showers at the end of the period, slightly milder.

DAYS 11-15 (DECEMBER 21-25)

Watching the period December 21-23 for a potential storm threat. Temperatures variable, close to normal overall.

C-19 Chat Post – December 11 2020

DAYS 1-5 (DECEMBER 10-14)

The geomagnetic storm that was expected to trigger a display of the aurora borealis (northern lights) did not arrive as aggressively as was anticipated last night, which ended up a moot point since we stayed generally overcast. But drier air is working in now, and stratocumulus clouds that are still around to start today will decrease and the sky should be clear by this evening, when we have a better chance at an occurrence of the northern lights, this time on the earlier side of evening. Again, no guarantee we’ll see it, but to maximize your chance, try to be away from lights and have a clear view to the north from as high an elevation as you can. They would appear most likely as a greenish and/or yellowish glow fairly close to and for a short distance above the horizon. It’s rare to see them much higher up at our latitude, and it’s even more rare to see the reddish color they can produce. But we will see what, if anything, happens. As far as our weather, dry weather courtesy high pressure through Friday. Then we have some unsettled weather moving in from the weekend. High pressure will be located in eastern Canada as low pressure makes an attempt to cut northwest of New England via the Great Lakes. While it will be successful in taking this track and travelling down the St. Lawrence Valley by Sunday, its warm front will struggle, as is typical, to move northward through the region on Saturday, which, while not cold, will also not warm up in any great hurry, along with cloudiness and periods of rain, favoring the later portion of the day into Saturday night. As stated yesterday, the position of that front will determine who gets a cold frontal passage and who gets an occluded frontal passage on Sunday, which will also be unsettled, but with the greatest chance of any rainfall in the morning. So if you are still needing to finish some outside decorations or pick up a Christmas tree this weekend, lean toward earlier Saturday and/or later Sunday. A trough of low pressure will pass through the region Monday, delivering a shot of colder air, perhaps with a few snow showers.

TODAY: Sun and passing clouds. Highs 38-45. Wind NW 5-15 MPH.

TONIGHT: Clear. Lows 20-27. Wind W under 10 MPH.

FRIDAY: Sun and high clouds. Highs 40-47. Wind SW up to 10 MPH.

FRIDAY NIGHT: Increasing clouds. Lows 30-37. Wind SE under 10 MPH.

SATURDAY: Mostly cloudy. Chance of light rain, mainly in the afternoon. Highs 45-52 except 38-45 in northern MA and southern NH Wind SE up to 10 MPH.

SATURDAY NIGHT: Cloudy. Spotty light rain except possible pockets of freezing rain southern NH and northern MA. Lows 31-38. Winds NE under 10 MPH.

SUNDAY: Mostly cloudy. Rain showers likely, mainly during the morning. Highs 40-47. Wind variable 5-15 MPH.

SUNDAY NIGHT: Variably cloudy. Lows 28-35. Wind W 5-15 MPH.

MONDAY: Partly cloudy. Chance of a passing snow shower. Highs 35-42. Wind NW 10-20 MPH, higher gusts.

DAYS 6-10 (DECEMBER 15-19)

High pressure will bring dry and cold weather to the region December 15. Next storm threat (rain/mix/snow) comes during the December 16-17 period, details to be determined by the track of a low pressure system. Colder/drier weather follows this.

DAYS 11-15 (DECEMBER 20-24)

Watching the period December 21-23 for a potential storm threat. Temperatures variable, close to normal overall.

C-19 Chat Post – December 10 2020

DAYS 1-5 (DECEMBER 9-13)

Sorry for the late update today. Technology sometimes has other plans. Anyway nothing really has changed since yesterday’s discussion. today we have a week low pressure area moving through the region from northwest to southeast, dragging a warm front / cold front combo across our area as the parent low passes to our north. This is generally a moisture starved system but with cold air in place anything will be in the form of light snow or perhaps a mix of snow sleet and rain. This system will move beyond our area tonight and be replaced by a gusty northwesterly breeze and reinforcement of chilly air for Thursday. but the high pressure system that delivers that cool air will move quickly to the southeast and allow slightly mild air to arrive by Friday. This weekend still looks unsettled as low pressure approaches from the west. Model guidance has wanted to take this low well north of the region and even though the primary center of low pressure may eventually pass to the north of here, it’s a tendent warm front may never clear the region. This will be due to high pressure in eastern Canada and a cold air damming setup. We may even see a secondary low pressure area form on the warm front or the triple point where the warm front and cold front intersect to become an occlusion. areas that do get into the warm air will see a true cold frontal passage during Sunday while areas that never get into it will see the occluded portion of the front pass by. Most of the precipitation that falls this weekend, while not heavy, would be in the form of rain, but with marginal surface temperatures a potential especially north of I-90 I could resolve in the possibility of some sleet or freezing rain/drizzle. that will be something we will have to keep an eye out for, depending on the timing of any precipitation. Since this is day four and five of the forecast I will keep the wording vague for now and fine tune as we get closer.

TODAY: Variably cloudy. A few periods of very light to light snow and/or mix possible. Highs 35-42. Wind NW to W 5-15 MPH.

TONIGHT: Variably cloudy with a risk of snow showers early, then clearing. Lows 20-27. Wind NW 5-15 MPH, a few higher gusts.

THURSDAY: Sun and passing clouds. Highs 38-45. Wind NW 10-20 MPH, diminishing.

THURSDAY NIGHT: Clear. Lows 20-27. Wind W under 10 MPH.

FRIDAY: Sun and high clouds. Highs 40-47. Wind SW up to 10 MPH.

FRIDAY NIGHT: Increasing clouds. Lows 30-37. Wind SE under 10 MPH.

SATURDAY: Mostly cloudy. Chance of light rain. Highs 45-52 except 38-45 in northern MA and southern NH Wind SE up to 10 MPH.

SATURDAY NIGHT: Cloudy. Spotty light rain except possible pockets of freezing rain southern NH and northern MA. Lows 31-38. Winds NE under 10 MPH.

SUNDAY: Mostly cloudy. Rain showers likely. Highs 40-47. Wind variable 5-15 MPH.

DAYS 6-10 (DECEMBER 14-18)

High pressure is expected to bring fair and seasonably cool weather early next week. Next storm threat with rain/mix/snow comes by the middle to end of the period.

DAYS 11-15 (DECEMBER 19-23)

A cold front may bring some mix/snow showers early period. Next storm threat comes middle to later portion of the period.

C-19 Chat Post – December 9 2020

DAYS 1-5 (DECEMBER 8-12)

The circulation around an offshore storm brings some rain/snow showers to the South Shore of MA and Cape Cod for a while today before the storm moves away to sea. A weaker low pressure area will move rapidly east southeastward across the region Wednesday but at most will produce a few flakes of snow with its warm frontal passage during the day and a few rain and snow showers with its cold frontal passage during the evening. High pressure brings fair weather Thursday-Friday before the warm front from approaching low pressure brings cloudiness and a chance of some rain by Saturday. We’ll probably stay north of that frontal boundary but it will be too warm aloft to support any frozen precipitation.

TODAY: Mostly cloudy to partly sunny. Chance of snow and rain showers MA East Coast especially South Shore as well as Cape Cod. Highs 35-42. Wind NE to N up to 15 MPH, a few gusts to 25 MPH possible Cape Cod.

TONIGHT: Variably cloudy. A lingering snow flurry near Cape Cod early. Lows 18-25. Wind N to NW 5-15 MPH.

WEDNESDAY: Variably cloudy. Brief very light snow mainly north of Boston midday. Passing rain and snow showers possible, mainly late-day favoring areas northwest of Boston. Highs 35-42. Wind NW to W 5-15 MPH.

WEDNESDAY NIGHT: Variably cloudy with a risk of snow or rain showers early, then clearing. Lows 20-27. Wind NW 5-15 MPH, a few higher gusts.

THURSDAY: Sun and passing clouds. Highs 38-45. Wind NW 10-20 MPH, diminishing.

THURSDAY NIGHT: Clear. Lows 20-27. Wind W under 10 MPH.

FRIDAY: Sun and high clouds. Highs 40-47. Wind SW up to 10 MPH.

FRIDAY NIGHT: Increasing clouds. Lows 30-37. Wind SE under 10 MPH.

SATURDAY: Mostly cloudy. Chance of light rain. Highs 45-52. Wind SE up to 10 MPH.

DAYS 6-10 (DECEMBER 13-17)

Low pressure passes north of the region Sunday with a frontal boundary bringing a chance of rain showers, followed by clearing and a gusty breeze. High pressure is expected to bring fair and seasonably cool weather early next week. Next storm threat with rain/mix/snow comes late in the period.

DAYS 11-15 (DECEMBER 17-21)

A cold front may bring some mix/snow showers early or mid period. Next storm threat comes later in the period.

C-19 Chat Post – December 8 2020

DAYS 1-5 (DECEMBER 7-11)

High pressure brings dry and cold weather today, but we’ll already be impacted in a way by the developing low to the south that we’ve been eyeing for early this week. That system will spread high to mid level cloudiness across the sky during the day today, eventually limiting the short-lived sunshine, which is now setting at its earliest of the year (4:11 p.m. at Boston). That storm system, passing southeast of the region on Tuesday, will indeed be far enough offshore to avoid direct impact, but the northeast to north wind on the back side of its circulation will pick up enough Atlantic moisture to deliver snow & rain showers to the MA East Coast, especially the South Shore, as well as Cape Cod. There is the possibility for some minor snowfall accumulation if any location that sees persistent snow showers, but this would be localized and would melt away after it stopped falling. If a little snow should fall on an ice patch, it can create a very small but very hazardous “slip & slide” zone, and one you probably don’t want your foot finding, so keep that in mind should you live in an area that gets dusted with snow – otherwise this will not be a big deal. The next disturbance will dive southeastward out of Canada, a bit more quickly than I previously thought, bringing some cloudiness and a few snow showers later Wednesday. Again these should be non-impactful, but there is always the chance that one briefly moderate snow shower could cause a brief dusting on some surfaces. High pressure builds in Thursday and Friday with fair weather.

TODAY: Sunny morning. Increasing clouds afternoon. Highs 33-40. Wind NW up to 10 MPH.

TONIGHT: Mostly cloudy. Slight chance of snow showers MA East Coast. Lows 25-32. Wind N to NE up to 10 MPH.

TUESDAY: Mostly cloudy to partly sunny. Chance of snow and rain showers MA East Coast especially South Shore as well as Cape Cod. Highs 35-42. Wind NE to N up to 15 MPH, a few gusts to 25 MPH possible Cape Cod.

TUESDAY NIGHT: Variably cloudy. A lingering snow flurry near Cape Cod early. Lows 18-25. Wind N to NW 5-15 MPH.

WEDNESDAY: Variably cloudy. Passing rain and snow showers possible, mainly afternoon and favoring areas west and north of Boston. Highs 35-42. Wind NW to W 5-15 MPH.

WEDNESDAY NIGHT: Variably cloudy with a risk of snow showers early, then clearing. Lows 20-27. Wind NW 5-15 MPH, a few higher gusts.

THURSDAY: Sun and passing clouds. Highs 38-45. Wind NW 10-20 MPH, diminishing.

THURSDAY NIGHT: Clear. Lows 20-27. Wind W under 10 MPH.

FRIDAY: Sun and high clouds. Highs 40-47. Wind SW up to 10 MPH.

DAYS 6-10 (DECEMBER 12-16)

Weekend storm system brings some unsettled weather but temperature profile is somewhat uncertain, dependent on the position of frontal boundaries. Will refine this forecast as we go through the week. Fair, seasonably chilly weather follows this but another low pressure area may bring a chance of rain/mix/snow by the end of the period.

DAYS 11-15 (DECEMBER 17-21)

Chance of rain/mix/snow early in the period depending on the development and track of low pressure. Fair, colder to follow.

C-19 Chat Post – December 7 2020