C-19 Chat Post – December 24 2020

DAYS 1-5 (DECEMBER 23-27)

Don’t look now, but we’ve already gained 10 seconds of daylight back! You won’t really notice it for a week or 2, but the days are indeed getting longer, post-solstice. The rate of increase is very slow at first, but will pick up the pace as we head through the winter. Speaking of winter, it will feel like it today as high pressure brings dry and seasonably cold weather to our region. You’ll notice some high cloudiness starting to increase as the day goes on. This is a signal of the approach of a warmer air mass. The warmer air, being less dense than colder air, rides up and over it at first, creating the high clouds. Eventually that warmer air mass will arrive at the surface in a gradual way on Thursday, which will feature lots of clouds but some intervals of sun. I expect the daylight hours to be rain-free. As we get deeper into Christmas Eve, our rain shower chance will go up, but it looks like most of the rainfall will hold off until the pre-dawn hours of Christmas morning for arrival, and a ribbon of moderate to heavy rain showers will traverse the region during the morning, exiting west to east by midday and afternoon. During the wet weather time will be the strongest winds, from the south, 15-30 MPH with gusts in the 35-55 MPH range. A few gusts above that are possible in higher elevations, such as Blue Hill in Milton MA. After the main rain shower area exits, the wind, while still gusty, will have shifted to the west and dropped off somewhat during the remainder of Christmas Day, and a stray snow shower may wander into the region as a breakaway from a Great Lakes snow squalls. Canadian high pressure builds in for the weekend with cold and dry conditions.

TODAY: Mostly sunny. Highs 33-40. Wind NW 5-15 MPH, diminishing.

TONIGHT: Partly cloudy. Lows 20-27. Wind SW up to 10 MPH.

THURSDAY: Mostly cloudy. Highs 45-52. Wind S 5-15 MPH.

THURSDAY NIGHT (CHRISTMAS EVE): Cloudy. Rain showers likely, mainly overnight. Temperatures rise to 48-55. Wind S 15-25 MPH, higher gusts, as high as 40-50 MPH especially in coastal areas and higher elevations, strongest toward dawn.

FRIDAY (CHRISTMAS DAY): Cloudy morning with rain showers, some heavy. Breaking clouds and rain showers ending early afternoon, then a risk of a snow shower late rin the day. Highs 50-57 early then temperatures fall through the 40s and into the 30s. Wind S 15-25 MPH with higher gusts, shifting to W.

FRIDAY NIGHT: Variably cloudy with a chance of snow showers. Lows 18-25. Wind W 15-25 MPH and gusty.

SATURDAY: Sun and passing clouds. Highs 28-35. Wind W 10-20 MPH and gusty.

SATURDAY NIGHT: Clear. Lows 15-22. Wind NW 5-10 MPH.

SUNDAY: Mostly sunny. Highs 32-39. Wind variable 5-15 MPH.

DAYS 6-10 (DECEMBER 28 – JANUARY 1)

Unsettled weather threat in the December 28-29 period, early indications are low pressure passing north of here with rain and snow showers. Fair and seasonably chilly weather returns to end the year, then the next storm threat looms for New Year’s Day.

DAYS 11-15 (JANUARY 2-6)

Dry/chilly January 2-3, milder/unsettled January 4-5, colder/dry January 6.

C-19 Chat Post – December 23 2020

DAYS 1-5 (DECEMBER 22-26)

Drying air eliminates any patchy fog early today and then we will see a sun/cloud mix as an upper level disturbance crosses the region, but with only a minimal chance of a passing snow flurry. This system will result mainly a shot of chilly air with gusty winds developing. It will remain cold but become more tranquil Wednesday as high pressure crosses the region. This high shifts offshore and allows temperatures to moderate on Christmas Eve as a low pressure area heads northeastward into southeastern Canada via the Great Lakes. The strong cold front trailing from this low will develop a wave of low pressure over the Appalachians which will move through NY in the early hours of Christmas Day and whip the front through the region with a short period of rain showers and very mild air, then a quick temperature drop behind it with drying weather and just a chance of a few snow showers surviving the trip from the Great Lakes region. Look for a chilly and breezy but dry Saturday between low pressure in the Canadian Maritimes and high pressure in the Appalachians.

TODAY: Any early freezing fog patches dissipate but watch for areas of black ice. Sun/cloud mix. Slight chance of a passing light snow shower. Highs 34-41. Wind NW 5-15 MPH, higher gusts.

Mostly cloudy. Snow showers likely, except rain or snow showers South Coast. Highs 35-42. Wind W 5-15 MPH, higher gusts.

TONIGHT: Clearing. Lows 15-22. Wind NW 5-15 MPH, higher gusts.

WEDNESDAY: Mostly sunny. Highs 31-38. Wind NW 5-15 MPH, diminishing.

WEDNESDAY NIGHT: Mostly clear. Lows 18-25. Wind SW up to 10 MPH.

THURSDAY: Partly sunny. Highs 38-45. Wind S 5-15 MPH.

THURSDAY NIGHT (CHRISTMAS EVE): Cloudy. Rain showers likely. Temperatures rise to 48-55. Wind S 15-25 MPH, higher gusts, as high as 40-50 MPH especially in coastal areas and higher elevations,.

FRIDAY (CHRISTMAS DAY): Cloudy start with rain showers possibly ending as snow showers, then a sun/cloud mix with a possible snow shower. Highs 50-57 early then temperatures fall through the 40s and into the 30s. Wind S 15-25 MPH with higher gusts, shifting to W.

FRIDAY NIGHT: Variably cloudy with a chance of snow showers. Lows 18-25. Wind W 15-25 MPH and gusty.

SATURDAY: Sun and passing clouds. Highs 28-35. Wind W 10-20 MPH and gusty.

DAYS 6-10 (DECEMBER 27-31)

Fair and seasonably cold December 27. A storm threat in the December 28-29 period. Fair and seasonably chilly weather returns to end the year.

DAYS 11-15 (JANUARY 1-5)

2021 may begin with a rain/mix/snow threat followed by dry weather, a cold shot, then moderation.

C-19 Chat Post – December 22 2020

DAYS 1-5 (DECEMBER 21-25)

Welcome to winter! Last year’s solstice sunrise was brilliant, whereas this one was obscured by low clouds and fog. in many areas the temperatures have been below freezing and some of that fog has contributed to icing on untreated surfaces so use caution if you are outside this morning. Some drying between an offshore storm system and an approaching trough from the west should result in partial clearing at times today and early this evening. This leaves us still with a chance to see the conjunction of Saturn and Jupiter low in the southwest sky between 5:00 p.m. and 7:00 p.m. The system coming from the west may produce some snow showers on Tuesday and behind it comes a reinforcing shot of cold air as high pressure moves in on Wednesday. I believe we are still seeing model corrections on going for the situation on Christmas Eve and Christmas Day. High pressure offshore will allow milder air to flow into the region on Christmas Eve. An approaching front from the west will bring rain showers to the region that night and into the early hours of Christmas Day before a rapid temperature drop which may end the rain as snow in some sections. Still have some fine tuning to do on this forecast for future updates.

TODAY: Clouds and areas of fog to start. Early rain Cape Cod. Clouds break for sun at times. Highs 35-42. Wind variable up to 10 MPH.

TONIGHT: Clouds return west to east. Lows 23-30. Wind variable 5-15 MPH.

TUESDAY: Mostly cloudy. Snow showers likely, except rain or snow showers South Coast. Highs 34-41. Wind NW 5-15 MPH, higher gusts.

TUESDAY NIGHT: Clearing. Lows 15-22. Wind NW 5-15 MPH.

WEDNESDAY: Mostly sunny. Highs 31-38. Wind W 5-15 MPH.

WEDNESDAY NIGHT: Mostly clear. Lows 18-25. Wind SW up to 10 MPH.

THURSDAY: Partly sunny. Highs 38-45. Wind S 5-15 MPH.

THURSDAY NIGHT (CHRISTMAS EVE): Cloudy. Rain showers likely. Temperatures rise to 48-55. Wind S 10-20 MPH, higher gusts.

FRIDAY (CHRISTMAS DAY): Cloudy start with rain showers possibly ending as snow showers, then a sun/cloud mix with a possible snow shower. Temperatures fall to the 20s. Wind W 15-25 MPH, higher gusts.

DAYS 6-10 (DECEMBER 26-30)

Fair, chilly weather expected for December 26-28 and then a risk of a wintry weather threat to end the period.

DAYS 11-15 (DECEMBER 31 – JANUARY 4)

Tranquil weather for the last day of 2020 before a quick-moving system brings some unsettled weather to greet 2021, followed by a shot of colder, dry weather.

C-19 Chat Post – December 21 2020

DAYS 1-5 (DECEMBER 20-24)

A weak area of low pressure passes through the region during today with lots of clouds and some rain and snow shower activity, rain showers favoring Cape Cod & coastal areas with snow showers favoring inland spots. Other than the risk of brief coatings of snow, this will have very little impact. Another low pressure area will develop on an offshore frontal boundary on Monday but should scoot just southeast and east of New England, a fairly close shave though, with some cloudiness and even a chance of a period of rain on Cape Cod. Meanwhile, another area of energy will be diving through the Great Lakes and while not able to catch up to the offshore storm in time to give it a shot of energy, it should bring some mix/snow shower activity to our area on Tuesday. I’m still hopeful that we’ll have just enough clear sky between these systems to be able to view the great conjunction of Jupiter & Saturn in the southwestern sky at dusk Monday. When we get to midweek, high pressure to the west brings fair and cold weather Wednesday, then slides offshore with moderation on Thursday, Christmas Eve. The next system to the west likely holds off so that dry weather will also be expected for Santa’s visit later Thursday night…

TODAY: Mostly cloudy. Showers of rain and snow around mainly afternoon. Highs 33-40. Wind variable 5-15 MPH.

TONIGHT: Mostly cloudy early, then clearing. Lows 21-28. Wind W 5-15 MPH.

MONDAY: Early and late sun, a period of cloudiness between which may include brief rain on Cape Cod and Nantucket. Highs 35-42. Wind W 5-15 MPH.

MONDAY NIGHT: Clouds return west to east. Lows 23-30. Wind variable 5-15 MPH.

TUESDAY: Mostly cloudy. Snow showers likely, except rain or snow showers South Coast. Highs 34-41. Wind NW 5-15 MPH, higher gusts.

TUESDAY NIGHT: Clearing. Lows 15-22. Wind NW 5-15 MPH.

WEDNESDAY: Mostly sunny. Highs 31-38. Wind W 5-15 MPH.

WEDNESDAY NIGHT: Mostly clear. Lows 18-25. Wind SW up to 10 MPH.

THURSDAY: Partly sunny. Highs 38-45. Wind S 5-15 MPH.

DAYS 6-10 (DECEMBER 25-29)

A frontal boundary with a couple low pressure areas on it will bring unsettled weather to the region for Christmas Day, December 25, but the exact evolution and behavior of this system is somewhat in question. Current thinking is a brief shot of mild air and rather short-lived period of rain showers for the morning, followed by a sharp temperature drop with a shifting wind and a chance of snow showers. Fair, chilly weather expected for December 26-28 and then a risk of a wintry weather threat to end the period.

DAYS 11-15 (DECEMBER 30 – JANUARY 3)

Low confidence forecast but current idea is for fair and tranquil weather for the last couple days of 2020 before a quick-moving system brings some unsettled weather to greet 2021, followed by a shot of colder, dry weather.

C-19 Chat Post – December 20 2020

DAYS 1-5 (DECEMBER 19-23)

A true weather nut will be fascinated by the contrast across our area during the nighttime hours leading up to sunrise when I started writing this blog. While many areas were clear and calm with significant radiational cooling over a fresh snow cover, dropping temperatures into the teens and single digits, even to near zero in some locations, cloud cover (with a few snow flurries) and a breeze did their job holding temperatures up in the 20s to even around 30 along the South Shore of MA and especially Cape Cod, and even Cape Ann from Gloucester through Rockport, as the western edge of the northerly air flow behind our recent storm continued unimpeded by the low friction of the ocean water. As today goes on, our temperatures will find themselves much more uniform across the region by early afternoon in comparison to how they started out the day, but it will be a cold day, albeit with plenty of sunshine, which will start to fade later in the day as we get an increase in high and mid level cloudiness in advance of our next disturbance. Unfortunately this will interfere with the view of Jupiter & Saturn, which draw ever closer in the sky on the way to their Grand Conjunction in just 2 days. But the weather has the say, and these clouds are going to move in, and the disturbance causing them will bring slightly milder air but also the chance of some light rain & snow shower activity on Sunday. This will not be a big deal, with rain showers most likely in coastal areas and Cape Cod while interior sections see a better chance of snow showers, where a minor accumulation could result in few slick spots. This system moves out Sunday evening, but probably again not in time to see the planets, leaving us one more chance on the day-of Grand Conjunction, Monday, also the Winter Solstice. But will see see it even then? That’s a good question. I have been keeping an eye on the potential evolution of another storm to threaten us on Tuesday, although the leaning has been for this to stay mostly offshore. But the evolution of this system may be a little different than I’d envisioned earlier, with 2 piece of energy not getting close enough to join up and create a larger storm. If this is indeed to be the case, what we will see is the southern energy sliding offshore south and east of us Monday with some high cloudiness that could exit in time for evening twilight planet viewing, and cloudiness from the northern piece of energy, while approaching via the Great Lakes, still holding off far enough to the west so as not to bother the view. Hoping this is how it turns out! Regardless, that northern energy is expected to dive across the region Tuesday with cloudiness and some snow shower activity (perhaps rain showers Cape Cod with more marginal temperatures), but not a big storm. Behind that comes high pressure and dry weather for Wednesday.

TODAY: Mostly sunny. Highs 30-37. Wind W 5-15 MPH.

TONIGHT: Variably cloudy. Lows 20-27. Wind SW up to 10 MPH.

SUNDAY: Mostly cloudy. Periods of light snow/mix/rain, frozen precipitation most likely Boston north and west, with rain more likely to the southeast. Highs 33-40. Wind variable 5-15 MPH.

SUNDAY NIGHT: Mostly cloudy early, then clearing. Lows 21-28. Wind W 5-15 MPH.

MONDAY: Early and late sun, a period of cloudiness between. Highs 35-42. Wind W 5-15 MPH.

MONDAY NIGHT: Clouds return. Lows 23-30. Wind variable 5-15 MPH.

TUESDAY: Mostly cloudy. Snow showers likely, except rain or snow showers South Coast. Highs 34-41. Wind NW 5-15 MPH, higher gusts.

TUESDAY NIGHT: Clearing. Lows 15-22. Wind NW 5-15 MPH.

WEDNESDAY: Mostly sunny. Highs 31-38. Wind W 5-15 MPH.

DAYS 6-10 (DECEMBER 24-28)

High pressure shifts offshore with dry but a little milder for December 24. Low pressure attempts a track northwest of New England for early December 25 but how much warm air gets into the region is questionable. While guidance will show a strong surge of southerly air, warmth, and a good slug of rain, I have my doubts this is exactly how it plays out. While we may eventually get into the “warm sector”, it will likely be difficult at first and also modified by snow cover, which will still very much be around in most of the region, and the rainfall along the frontal boundary that sweeps through from the west may be a much narrower area than depicted by models at this time. Cold air likely returns rather quickly by later December 25 hanging around for the remainder of this period as high pressure builds across the Great Lakes and into eastern Canada.

DAYS 11-15 (DECEMBER 29 – JANUARY 2)

High pressure eastern Canada, low pressure approaching from west may bring a wintry weather event to start this period followed by a brief shot of cold, then moderation with more tranquil weather as 2021 arrives. This is a low confidence forecast at this time.

C-19 Chat Post – December 19 2020

DAYS 1-5 (DECEMBER 18-22)

Even though our departed storm is heading into the Canadian Maritimes, it continues to have an impact on the region this morning in the form of extensive cloud cover, and even more of an impact from Plymouth County MA to Cape Cod where ocean-effect snow & freezing drizzle has been ongoing, keeping things on the treacherous side where they already saw a wetter snow with rain followed by a flash freeze with a fluffier snow yesterday. Regionwide, conditions will improve today as drier air moves in and clouds break apart and eventually clear from northwest to southeast. High pressure moves in tonight setting up a strong radiational cooling night over the fresh snow pack, and hangs around to give a nice day on Saturday. The next disturbance from the west arrives Saturday night with clouds and takes the day Sunday to pass through with some rain and snow shower activity, but this will be a minor system with minimal impact. A weak ridge of high pressure brings fair weather for Monday, but an upper trough quickly swinging through the region Monday night and Tuesday will ignite a storm offshore. At this time the guidance has this system just too far offshore to be of an impact, precipitation-wise, but we should watch it carefully, given recent guidance performance in advance of such events. Either way, this system will help drag in more Canadian cold later Tuesday.

TODAY: Cloudy start including periods of light snow and/or freezing drizzle from Plymouth County MA to Cape Cod, gradually ending by about midday. Clearing with sun returning from northwest to southeast midday/afternoon. Highs 26-33. Wind NE-N 5-15 MPH morning shifting to N-NW this afternoon.

TONIGHT: Clear. Lows 3-10 except 10-17 urban centers and coastal areas. Wind NW under 10 MPH.

SATURDAY: Mostly sunny. Highs 30-37. Wind W 5-15 MPH.

SATURDAY NIGHT: Variably cloudy. Lows 20-27. Wind SW up to 10 MPH.

SUNDAY: Mostly cloudy. Periods of light snow/mix/rain. Highs 33-40. Wind variable 5-15 MPH.

SUNDAY NIGHT: Mostly cloudy early, then clearing. Lows 21-28. Wind W 5-15 MPH.

MONDAY: Partly cloudy. Highs 35-42. Wind W 5-15 MPH.

MONDAY NIGHT: Mostly cloudy. Lows 23-30. Wind variable 5-15 MPH.

TUESDAY: Mostly cloudy start with a chance of snow/mix favoring Cape Cod, then cloud/sun mix with a risk of a passing snow shower. Highs 35-42 but temperatures likely falling in the afternoon. Wind N 10-20 MPH, gusty.

DAYS 6-10 (DECEMBER 23-27)

Dry, cold December 23 as high pressure moves in then crosses the area. December 24 & 25 bring the next chance for some unsettled weather with early indications for low pressure tracking northwest of the region bringing a warm front / cold front combo through with some mix/rain with the warm front, a surge of milder air, and then rain showers with the cold front, followed by a sharp temperature drop and perhaps some snow showers. Caveat: I don’t necessarily trust the guidance depiction of this event yet, so changes to this outlook are possible. Dry/seasonable later in the period.

DAYS 11-15 (DECEMBER 28 – JANUARY 1)

One or two precipitation events possible during this period, favoring December 28 & 30. Shot of cold air arrives early period then some moderation follows. Low confidence outlook with much re-analysis needed.

C-19 Chat Post – December 18 2020

DAYS 1-5 (DECEMBER 17-21)

The WHW forecast area continues to be impacted by a winter storm, dumping a good amount of snow on much of the region, with a bit less to the southeast due to wetter snow, and even less on parts of the outer part of Cape Cod and over the Islands due to a change to rain there . The mix/rain areas will see a flip back to snow before the end of the precipitation, and areas that had rain and wetter snow will experience a quick freeze-up when the cold air returns during the midday and afternoon hours today. There is also a drier slot with less or even no snow falling in the Merrimack Valley through parts of central MA. These areas will see additional snowfall though as a heavier band to the north and west rotates back through while weakening. Eventually all of the snow will move out from west to east, ending with accumulation with most areas somewhere in the expected ranges. Tonight comes clearing and mid winter cold, despite it still being autumn. Colder than normal but dry weather will dominate Friday and Saturday. Sunday will see slight temperature moderation but also some cloudiness and the possibility of snow and rain showers as a weak low passes by. Following this should be weak high pressure with a dry, seasonable Monday.

TODAY: Overcast with snow except mix/rain South Coast and Cape Cod for a while before changing to snow by midday from west to east. Total snow accumulation: 1-2 inches lower portion of outer Cape Cod (Chatham) as well as Nantucket and Martha’s Vineyard, 2-4 inches upper portion of outer Cape Cod (Provincetown) as well as Mid Cape, 4-8 inches Cape Cod Canal area as well as South Shore up to about Plymouth and westward to the immediate coast of RI, and 8-14 inches elsewhere. Highs 25-32 north and west of Boston, 33-40 elsewhere with mildest Cape Cod and Islands in the morning, followed by falling temperatures midday and afternoon. Wind E to NE 15-25 MPH with gusts 35-45 MPH southeastern MA and southeastern RI, shifting to NW during the afternoon, and NE to NW 10-20 MPH with gusts 25-35 MPH elsewhere.

TONIGHT: Clearing. Blowing snow likely. Lows 10-18. Wind N to NW 10-20 MPH, higher gusts. Wind chill often below 10.

FRIDAY: Sun and passing clouds. Highs 27-34. Wind NW 10-20 MPH.

FRIDAY NIGHT: Clear. Lows 10-17. Wind NW under 10 MPH.

SATURDAY: Mostly sunny. Highs 30-37. Wind W 5-15 MPH.

SATURDAY NIGHT: Variably cloudy. Lows 20-27. Wind SW up to 10 MPH.

SUNDAY: Mostly cloudy. Chance of light snow/mix/rain Highs 33-40. Wind variable 5-15 MPH.

SUNDAY NIGHT: Mostly cloudy early, then clearing. Lows 21-28. Wind W 5-15 MPH.

MONDAY: Partly cloudy. Highs 35-42. Wind W 5-15 MPH.

DAYS 6-10 (DECEMBER 22-26)

Potential unsettled weather events December 22 and 24-25. Temperatures near to slightly above normal dropping to below normal at the end of the period.

DAYS 11-15 (DECEMBER 27-31)

One or two precipitation events possible during this period. Temperatures start cold then moderate.

C-19 Chat Post – December 17 2020