Thursday December 31 2020 Forecast (7:37AM)

DAYS 1-5 (DECEMBER 31 – JANUARY 4)

On this final day of 2020, we won’t see much sun, but after morning rainfall exits the South Coast region, it will be a dry day. High pressure building across eastern Canada and pushing down into New England will bring some clearing tonight and 2021’s first day will dawn with sunshine, but clouds will advance steadily as the day goes on and another low pressure area approaches from the southwest. This system will have colder air to work with so snow & sleet are likely to be at the leading edge of the precipitation shield of this low pressure area when it arrives on Friday evening, but warmer air aloft will change that to rain during the night and into Saturday morning. However some colder air trapped at the surface may result in some pocket of freezing rain mainly over interior valley locations before temperatures rise sufficiently to eliminate that issue. By Saturday afternoon, low pressure will have crossed the region and drier air will be moving in behind it. But this dry interlude will also be short-lived, as a follow-up low will pass by the region Sunday night into Monday with another period of precipitation, the details of which still need to be worked out.

TODAY: Mostly cloudy. Rain South Coast region this morning. Highs 42-49 this morning, then slowly falling temperatures during the afternoon hours. Wind W 5-15 MPH with higher gusts.

TONIGHT (NEW YEAR’S EVE): Clearing. Lows 18-25. Wind N 5-15 MPH evening, diminishing overnight.

FRIDAY: Sunshine fading behind increasing high cloudiness. Highs 32-39. Wind N up to 10 MPH.

FRIDAY NIGHT: Thickening overcast with snow/sleet northwestern areas and mix/rain southeastern areas arriving from southwest to northeast, changing to rain except possible freezing rain interior valley locations. Lows 30-37. Wind N to NE up to 10 MPH inland and 10-20 MPH coast.

SATURDAY: Cloudy with areas of fog and a chance of rain in the morning. Breaking clouds in the afternoon. Highs 45-52. Wind NE to variable 5-15 MPH becoming W.

SATURDAY NIGHT: Clearing. Lows 25-32. Watch for black ice formation. Wind W up to 10 MPH.

SUNDAY: Increasing clouds. Chance of rain/mix/snow by late in the day. Highs 36-43. Wind N up to 10 MPH.

SUNDAY NIGHT & MONDAY: Cloudy with rain/mix/snow possible. Temperatures 35-45. Wind NE to variable 10-20 MPH shifting to N.

DAYS 6-10 (JANUARY 5-9)

High pressure builds in with fair weather January 5. Weak system may bring a few rain/snow showers, milder on January 6. High pressure builds back in with fair weather January 7. Next threat of unsettled weather comes from passing low pressure about January 8 before dry/cold weather ends the period.

DAYS 11-15 (JANUARY 10-14)

Stronger indications of a blocking pattern setting up during this period. Will have to watch one or two low pressure areas, strongest chance for unsettled weather around January 12-13.

Wednesday December 30 2020 Forecast (7:34AM)

DAYS 1-5 (DECEMBER 30 – JANUARY 3)

After much of the region saw a very nice sunrise, an abundance of high & mid level cloudiness will limit sunshine today as a warm front moves across the region. The precipitation associated with this front, which is not too prominent anyway, will pass north of the WHW forecast area. This warm front is parented by low pressure which will be passing north of our area tonight and dragging its trailing cold front across the region Thursday morning, bringing with it a period of rainfall before drier air returns during the day from northwest to southeast with some partial clearing occurring. High pressure, initially under-forecast by guidance, will be quite strong as it builds across eastern Canada and exerts its influence on us here, bringing cold and dry weather for New Year’s Eve & New Year’s Day. If you recall, just a few days ago, most guidance had been calling for a repeat of the warm/set scenario of Christmas Day, but this is a vivid example of why we don’t just look at the models and make that the forecast. The storm system that this guidance was trying to track so quickly well northwest of our area is going to be a little slower-moving, and track much further southeast, passing right over the area early Saturday. Ahead of it, when its precipitation shield arrives during Friday night, it will likely be cold enough so that it begins as snow & sleet in some areas, especially away from the coast, but warmer air moving in aloft will change this precipitation to rain, although a period of icing is quite possible over interior locations, especially valleys, where surface cold air is always a lot harder to dislodge. Eventually, as low pressure moves east of us during Saturday, drier air will return, and we’ll see improvement in the majority of the region before the end of the day, but it now appears this improvement will be rather short-lived, into the first part of Sunday, before follow-up low pressure tracks south of the region, but close enough to bring its envelope of precipitation into at least the southeastern portion of the area by Sunday night. The timing and precipitation type details still need to be worked out, but odds favor a little bit more snowfall coverage with that one, provided it gets far enough north.

TODAY: Sunshine limited by high & mid level clouds. Highs 33-40. Wind W up to 10 MPH.

TONIGHT: Mostly cloudy. Rain, may begin as sleet, arriving in southern NH and northern MA pre-dawn. Lows 25-32 evening, rising through the 30s overnight. Wind S under 10 MPH.

THURSDAY: Cloudy morning with rain progressing southeastward through the region. Mostly cloudy to partly sunny afternoon. Highs 42-49. Wind SW 5-15 MPH shifting to NW.

THURSDAY NIGHT (NEW YEAR’S EVE): Partly cloudy. Lows 18-25. Wind N 5-15 MPH evening, diminishing overnight.

FRIDAY: Sunshine fading behind increasing high cloudiness. Highs 32-39. Wind N up to 10 MPH.

FRIDAY NIGHT: Thickening overcast with snow/sleet northwestern areas and mix/rain southeastern areas arriving from southwest to northeast, changing to rain except possible freezing rain interior valley locations. Lows 30-37. Wind N to NE up to 10 MPH inland and 10-20 MPH coast.

SATURDAY: Cloudy with areas of fog and a chance of rain in the morning. Breaking clouds in the afternoon. Highs 45-52. Wind NE to variable 5-15 MPH becoming W.

SATURDAY NIGHT: Partly cloudy. Lows 25-32. Watch for black ice formation. Wind W up to 10 MPH.

SUNDAY: Partly sunny. Snow/mix/rain possible at night. Highs 35-42. Wind N up to 10 MPH.

DAYS 6-10 (JANUARY 4-8)

Low pressure passing southeast of the region may impact the area with snow/mix/rain January 4. High pressure builds in with fair weather January 5. Weak system may bring a few rain/snow showers, milder on January 6. High pressure builds back in with fair weather January 7. Next threat of unsettled weather comes from passing low pressure about January 8. Temperatures variable, not too far from normal.

DAYS 11-15 (JANUARY 9-13)

Stronger indications of a blocking pattern setting up during this period. Generally dry and seasonably cold weather to start out in our area, but a chance of some unsettled / wintry weather comes later in the period.

Tuesday December 29 2020 Forecast (7:32AM)

DAYS 1-5 (DECEMBER 29 – JANUARY 2)

High pressure builds into the region today, which will be breezy, cold, & dry. High pressure crests over the region Wednesday with cold, tranquil weather, but you’ll notice an increase in high cloudiness ahead of a warm front, which will quietly move through the region during the evening hours as a lead low pressure area tracks north of the region. This low will drag a cold front through here Thursday morning with cloudiness and a rain shower risk, as a shot of milder air will have moved in behind the warm front and ahead of the cold front. The entire evolution of the New Year’s Eve & New Year’s Day set-up looks different on recent guidance than it did on previous guidance, which was showing a set-up very similar to that of last week (Christmas Eve / Christmas Day). But we know guidance has been struggling, but seems to have resolved at least to the idea of the weaker low passing north late Wednesday & early Thursday, high pressure building across eastern Canada to bring some colder air back in for New Year’s Eve, and then low pressure from the southwest making a run at our area later Friday into Saturday. The details of this particular low pressure area are still not worked out, but the general idea is that the onset of precipitation sometime Friday afternoon or evening may be in the form of snow/sleet & freezing rain for some areas, especially away from the coast, before rain takes over, possibly leaving some pockets of freezing rain a bit longer over interior valleys, before tapering off at some point Saturday, depending on details of frontal boundaries and low pressure track. More fine-tuning needed there which will take place as we get closer to this event.

TODAY: Sun & passing clouds. Highs 32-39. Wind NW 10-20 MPH.

TONIGHT: Clearing. Lows 13-20. Wind NW 5-15 MPH, diminishing.

WEDNESDAY: Sun & high clouds. Highs 33-40. Wind W up to 10 MPH.

WEDNESDAY NIGHT: Mostly cloudy. Lows 23-30. Wind S under 10 MPH.

THURSDAY: Mostly cloudy with a chance of rain showers in the morning. Partly sunny in the afternoon. Highs 43-50, occurring in the morning. Wind SW 5-15 MPH shifting to NW.

THURSDAY NIGHT (NEW YEAR’S EVE): Partly cloudy. Lows 25-32. Wind N 5-15 MPH evening, diminishing overnight.

FRIDAY (NEW YEAR’S DAY): Clouding over. Snow and/or sleet & rain and/or freezing rain arriving from southwest to northeast by the end of the day. Highs 30-38. Wind N to NE 5-15 MPH.

FRIDAY NIGHT: Overcast with rain except pockets of freezing rain possible interior valley locations evening. Temperatures steady 30-38 evening, rising to 38-45 overnight. Wind N to NE 5-15 MPH, becoming variable.

SATURDAY: Cloudy with areas of fog and a chance of rain in the morning. Breaking clouds in the afternoon. Highs 45-52. Wind variable 5-15 MPH becoming W.

DAYS 6-10 (JANUARY 3-7)

High pressure noses in with cold/dry weather January 3. We’ll have to watch for low pressure passing south of the region January 4 which is handled very differently by various guidance, but right now my leaning is that it stays far enough south to bring only a minor threat of snow/mix/rain to the South Coast. High pressure brings dry/chilly weather January 5. Weak system may bring clouds and a minor precipitation threat about January 6 before fair weather returns at the end of the period.

DAYS 11-15 (JANUARY 8-12)

Best chances for unsettled weather come about January 8 & 12, but there is a lot of uncertainty with pattern evolution at this time. Will monitor for potential blocking. Not expecting guidance to handle pattern recognition very well for a while.

Monday December 28 2020 Forecast (7:34AM)

DAYS 1-5 (DECEMBER 28 – JANUARY 1)

The next-to-next-to-next-to-last day of 2020 (today) will be a mild one by late December standards as low pressure tracks east northeastward down the St. Lawrence Valley and a warm front goes by this morning followed by a late-day cold frontal passage. This moisture-starved system will bring only the threat of a rain shower ahead of or along its cold front and despite dominant cloudiness much of the day, we may see some clearing late today. The next-to-next-to-last day of 2020 (Tuesday) will feature a cold wind but dry weather with sun & a few clouds as we’ll be between departing low pressure in eastern Canada and approaching Canadian high pressure. The next-to-last day of 2020 (Wednesday) will be cold but tranquil as high pressure builds over the region, though some high cloudiness will show up. The last day of 2020 (Thursday a.k.a. New Year’s Eve), much like today, will feature lots of clouds and milder air ahead of yet another low pressure area taking a similar track north of our area, and there may be a few rain showers during the day, although these should exit by evening for any limited outdoor festivities taking place that night, just as colder air arrives. The first day of 2021 holds the most complex outlook of this 5-day period, as cold high pressure will have built into eastern Canada while another low pressure area approaches New England from the southwest. Cold air will be stubborn, at least at the surface, as the moisture from this system arrives during the day – a set-up for potential icing conditions and maybe some frozen precipitation, before rain becomes dominant, but all of this will depend on the depth of the cold air and how difficult it is to dislodge. Obviously, fine-tuning will be necessary as this event draws closer.

TODAY: Mostly cloudy through early afternoon then partial sun by late day. Chance of passing rain showers, especially during the afternoon hours. Highs 43-50. Wind S 10-20 MPH.

TONIGHT: Partly cloudy evening. Clearing overnight. Lows 26-31. Wind W 10-20 MPH.

TUESDAY: Sun & passing clouds. Highs 32-39. Wind NW 10-20 MPH.

TUESDAY NIGHT: Clearing. Lows 13-20. Wind NW 5-15 MPH, diminishing.

WEDNESDAY: Sun & high clouds. Highs 33-40. Wind W up to 10 MPH.

WEDNESDAY NIGHT: Partly cloudy. Lows 23-30. Wind S under 10 MPH.

THURSDAY: Mostly cloudy. Chance of rain showers. Highs 45-52. Wind SW 5-15 MPH.

THURSDAY NIGHT (NEW YEAR’S EVE): Mostly cloudy. Lows 28-35. Wind N 5-15 MPH evening, diminishing overnight.

FRIDAY (NEW YEAR’S DAY): Overcast. Rain arriving from southwest to northeast, may begin as freezing rain and/or sleet in some locations. Highs 33-40. Wind N to NE 5-15 MPH.

DAYS 6-10 (JANUARY 2-6)

Low pressure exits during January 2 which starts wet then ends dry & colder. High pressure builds in with dry and cold weather for January 3. Low pressure may pass close to or south of the region with an unsettled weather threat January 4 with the next system likely to be one passing north of the region with milder air and rain showers by January 6, but this being quite a few days away it’s not a high confidence outlook.

DAYS 11-15 (JANUARY 7-11)

Much of this period looks quiet other than a chance of some unsettled weather about January 8. The overall pattern may be shifting to more of a blocking set-up here though which has some potential implications for mid January.

Sunday December 27 2020 Forecast (8:34AM)

DAYS 1-5 (DECEMBER 27-31)

High pressure provides us with bright but cold weather today, and as we come down the home stretch to the finish line of 2020 we’ll be seeing a few more changes in the weather. First, a broad but moisture-starved area of low pressure passes north of our area Monday, dragging its warm front through the region during the morning with lots of cloudiness, then its cold front through in the afternoon with perhaps a rain shower as milder air will have taken over. But quickly behind this comes another shot of cold air between the departing low via eastern Canada and approaching high pressure in the Great Lakes Monday night and Tuesday with a gusty breeze. High pressure will settle over the region then slip to the south with fair and seasonably chilly weather Wednesday. By Thursday, weaker low pressure will travel eastward, passing north of this area but dragging a cold front through. This front may be accompanied by a few rain showers.

TODAY: Mostly sunny. Highs 34-41. Wind W 5-15 MPH becoming variable under 10 MPH.

TONIGHT: Increasing clouds. Lows 25-32. Wind S up to 10 MPH.

MONDAY: Mostly cloudy morning. Partly sunny with a passing rain shower possible afternoon. Highs 43-50. Wind S 10-20 MPH.

MONDAY NIGHT: Partly cloudy evening. Clearing overnight. Lows 26-31. Wind W 10-20 MPH.

TUESDAY: Sun/cloud mix. Highs 34-41. Wind NW 10-20 MPH.

TUESDAY NIGHT: Clearing. Lows 18-25. Wind NW 5-15 MPH.

WEDNESDAY: Sunny. Highs 33-40. Wind W 5-15 MPH, diminishing.

WEDNESDAY NIGHT: Partly cloudy. Lows 23-30. Wind S under 10 MPH.

THURSDAY: Variably cloudy. Chance of rain showers. Highs 45-52. Wind SW 5-15 MPH.

DAYS 6-10 (JANUARY 1-5)

As high pressure builds over eastern Canada and another low travels in our direction from the southwest, what yesterday’s guidance was showing more as a set-up similar to the one we had on Christmas, it now has been leaning toward a little more complex scenario where high pressure to the north is strong enough to force the low’s track a little further south and keep colder air in the region for New Year’s Day. This could be a set-up for a more complex precipitation situation, something we’ll have to keep a close eye on during the next several days. Any precipitation exits by early January 2 followed by dry/colder weather for the January 2-3 weekend. Temperatures moderate with a minor disturbance bringing a chance of mix/rain showers January 4 and/or 5.

DAYS 11-15 (JANUARY 6-10)

Best chances for unsettled weather from passing systems January 8 & 10. Evolution of pattern and storm track is a little uncertain at this time and we’ll be watching for some blocking to potentially set up before the end of this period which could shift the track of future storms more to the south.