Sunday January 31 2021 Forecast (8:14AM)

DAYS 1-5 (JANUARY 31- FEBRUARY 4)

The arctic air mass that has frozen us decently well over the last few days will be on the way out today, although it will still be a cold day, running below normal for the end of January. The high & mid level clouds you see in the sky are in advance of the coming winter storm that will impact the region later Monday through Tuesday, with greatest impact Monday night. This will happen as low pressure heads from the Ohio Valley to the northern Middle Atlantic Coast. This low never turn into a power house, but it will have an elongated center, first with a west-to-east orientation south of New England, then in response to upper level low pressure will rotate counterclockwise to more of a south-to-north orientation as it passes south and east of New England Monday through Tuesday, before moving away and organizing into a more formidable storm system in the Canadian Maritime Provinces on Wednesday. After that, high pressure will move in providing us with fair weather and not-too-cold air for Thursday.

Before I go to the detailed forecast here is an updated run-down of the aspects of the coming storm…

Arrival timing: Snow arrives south to north Monday afternoon but may be mixed with rain South Coast, Cape Cod, and MA South Shore.

Storm peak (heaviest precipitation): Monday night to very early Tuesday.

Snow amounts: Slushy under 1 inch tip of Cape Ann MA, immediate South Shore of MA south of Plymouth, Buzzards Bay region eastward through Cape Cod. 1-3 inches middle of Cape Ann MA, immediate MA South Shore south of Boston to Plymouth, southward just inland of the MA South Shore south of Plymouth to the western side of Buzzards Bay, 3-6 inches immediate NH Seacoast to immediate North Shore of MA, Logan Airport, interior southeastern MA to Narragansett Bay, 6-12 inches elsewhere with highest amounts in the I-495 belt west of Boston especially higher elevations.

Rain vs. snow: A rain/snow line will spend most of its time near the shoreline with southeastern MA especially Cape Cod in rain longest. This rain/snow line may migrate northwestward for a while during the storm, or even oscillate in response to precipitation intensity and is the reason for a very sharp snowfall gradient in the forecast. When you see this, there is a higher-than-usual potential that areas in this sharp gradient zone need a forecast adjustment.

Coastal impact: While not extremely strong, some significant and persistent onshore wind from the east and northeast, with some strong gusts across Cape Cod, then eventually more from the north, will probably result in minor to possibly moderate coastal flooding for the Monday afternoon, early Tuesday morning, and Tuesday afternoon high tides, with the greatest threat likely for the latter 2 high tide cycles.

Power outages: This will be a higher water content snow, so isolated to scattered power outages are possible, especially where snowfall accumulations are 4 or more inches. The stronger wind gusts along the coastline and especially over Cape Cod may also result in a few isolated power outages. Not expecting widespread power problems.

TODAY: Increasing clouds. Highs 25-32. Wind N under 10 MPH.

TONIGHT: Thickening overcast.. Lows 15-22. Wind NE up to 10 MPH.

MONDAY: Overcast. Snow arriving south to north during the afternoon at least into the I-90 belt, may be mixed with rain South Coast / Cape Cod. Highs 26-33 except 33-40 South Coast / Cape Cod. Wind NE to E increasing to 10-20 MPH, higher gusts especially coastal areas by late-day.

MONDAY NIGHT: Overcast. Moderate to heavy snow except mix coast and rain Cape Cod evening, tapering off to a few rain/snow showers south to north overnight. Temperatures rise slightly to 28-35 except 35-42 coastal areas, warmest Cape Cod. Wind E to NE 10-20 MPH with gusts as high as 30 MPH inland, 15-25 MPH with gusts as high as 40 MPH coastal areas, except 25-35 MPH with gusts 50-60 MPH Cape Cod.

TUESDAY: Cloudy. Occasional rain & snow showers. Highs 35-42 morning, falling slightly in the afternoon. Wind NE to N 10-20 MPH with gusts to 30 MPH inland and 15-25 MPH with gusts to 40 MPH coastal areas except 45-55 MPH Cape Cod, especially in the morning and midday.

TUESDAY NIGHT: Mostly cloudy. Additional mix/snow showers evening. Lows 25-32. Wind NW 10-20 MPH, higher gusts.

WEDNESDAY: Partly sunny. Highs 33-40. Wind NW 10-20 MPH, higher gusts.

WEDNESDAY NIGHT: Partly cloudy. Lows 22-29. Wind NW 5-15 MPH, higher gusts.

THURSDAY: Mostly sunny. Highs 36-43. Wind NW 5-15 MPH becoming variable.

DAYS 6-10 (FEBRUARY 5-9)

Next low pressure area passes well north of the region on February 5 with a warm front / cold front combo meaning maybe a brief light mix then a chance of rain showers. Additional unsettled weather possible during the February 6-7 weekend and possibly February 8 as colder air from the west slowly makes its way toward this area. Too early for detail on precipitation chances at this time. Fair, colder weather to end this period.

DAYS 11-15 (FEBRUARY 10-14)

Temperatures start cold then moderate, unsettled weather threat mid to late period. Low confidence forecast with a lot of re-evaluation needed.

Saturday January 30 2021 Forecast (8:38AM)

DAYS 1-5 (JANUARY 30- FEBRUARY 3)

Before we get into talking about the upcoming storm, let’s talk about the cold that still has hold of us. Another day today of well below normal temperatures, but this time less wind, so it won’t feel as harsh as yesterday. We’ll also have nearly 100% sunshine, which is now just starting to be noticeably a bit higher in the sky during the day than it was in the darkest days of late November through early January. It’s subtle, but it’s there, now being light well into the 5:00 p.m. hour. If you’re an early riser you’ve noticed the same on the other end of the day – that morning twilight starting a little earlier. In fact, Boston experienced its first sunrise before 7:00 a.m. today, 1 minute before. While the sunsets there are just a few days away from reaching the 5:00 p.m. or later threshold, we will probably only see the sun go down one of the next 4 days – today. Tomorrow is about a 50/50 shot and will depend on how quickly high cloudiness advance ahead of the coming storm, and how much they thicken up. But since they will be coming from the direction we’d be looking to see sunset, this is reducing our odds of seeing Sunday’s sunset. When we get to Monday we’ll be under a thickening blanket of altostratus clouds as our storm, a redevelopment of an Ohio Valley low, starts to make a northeastward movement to the south of New England. So definitely no sunset visible that day, nor will it be visible on Tuesday, the first day it occurs 5:00 p.m. or later at Boston, as we will still be under complete influence of that storm system, which will not be out of here until Wednesday, when we will actually visibly see our first post-5:00 p.m. sunset (at least in most of the region, pending any post-storm passing cloudiness). Hey, how did I get to Wednesday’s weather without talking in as much detail as I could about the storm? Don’t worry. I didn’t forget. I was just saving that until the last part of this discussion. You’re not getting snowfall amounts out of me yet, but you may start to see those in the comments section of the blog from me as we get deeper into the day and I get to look over another set of model guidance to get a better idea of how they are handling the evolution of this system. The energy for this system just came onshore on the West Coast yesterday, and it was with today’s 00z model guidance that we finally started to get better sampling for model initialization, and from here on in, in theory, the guidance should be performing the best it can under current reduced air travel circumstances. As always, the models are guidance, one set of tools in the meteorological process – one I hope leads me to a fairly accurate prognostication of upcoming events. And here is what I think so far, followed by a detailed forecast….

Storm timing: Snow arrives south to north Monday afternoon.

Storm peak (heaviest precipitation): Monday night to very early Tuesday.

Snow amounts: No numbers yet, but highest chance for the most significant accumulation currently expected in the I-95 belt and/or I-495 belt.

Rain vs. snow: A rain/snow line will probably be involved in this storm, most likely limiting snowfall near the coast especially southeastern MA.

Coastal impact: While not extremely strong, some significant and persistent onshore wind from the northeast & east will probably result in minor to possibly moderate coastal flooding focused on the high tide in the early hours of Tuesday morning. A more northerly wind may cause minor flooding on north-facing shores for the Tuesday afternoon high tide.

Duration of storm: While I’m leaning toward the heaviest precipitation being Monday night, it should be lighter and more spotty (still with a possible rain/snow line involved) through Tuesday, but that does not mean some areas cannot see additional snow accumulation.

TODAY: Sunny. Highs 18-25. Wind NW 5-15 MPH gusting 20-25 MPH morning, diminishing in the afternoon. Wind chill below 10 at times.

TONIGHT: Clear. Lows 0-7 except 8-15 urban centers. Wind NW under 10 MPH.

SUNDAY: Sunny start, variably cloudy finish. Highs 25-32. Wind N under 10 MPH.

SUNDAY NIGHT: High overcast. Lows 15-22. Wind NE up to 10 MPH.

MONDAY: Thickening overcast. Snow arriving south to north during the afternoon at least into the I-90 belt, may be mixed with rain South Coast / Cape Cod. Highs 26-33 except 33-40 South Coast / Cape Cod. Wind NE increasing to 10-20 MPH, higher gusts especially coastal areas by late-day.

MONDAY NIGHT: Overcast. Snow, possibly heavy at times, with significant accumulation possible, except rain/mix South Coast and possibly South Shore of MA. Temperatures steady 26-33 interior areas and North Shore of MA to NH Seacoast, steady or rising slightly 34-41 coastal areas to the south. Wind NE to E 10-20 MPH except 15-25 MPH coastal areas with higher gusts.

TUESDAY: Overcast. Periods of snow northwest of Boston, snow/mix/rain Boston south. Temperatures generally steady 26–33 interior locations, NH Seacoast, and North Shore of MA and 34-41 coastal areas Boston southward. Wind E backing to N 10-20 MPH inland and 15-30 MPH coast with higher gusts.

TUESDAY NIGHT: Mostly cloudy. Additional mix/snow showers evening. Lows 25-32. Wind N 10-20 MPH, higher gusts.

WEDNESDAY: Partly sunny. Highs 33-40. Wind NW 10-20 MPH, higher gusts.

DAYS 6-10 (FEBRUARY 4-8)

A shift in the large scale pattern as a plunge of arctic air enters the west central US and the East Coast moderates, meaning a milder trend for our area February 4-5. Next low pressure area travels well northwest of New England and its warm front / cold front combo brings a chance of some brief snow/mix/rain followed by rain showers sometime those two days. The February 6-8 period may see some additional unsettled weather with an active jet stream between very cold air to our northwest and milder air across the southeastern US.

DAYS 11-15 (FEBRUARY 9-13)

The cold air that moves into areas to our west and north will probably find its way to the Northeast with time, so expect colder weather for this period, probably starting out dry, but eventually ending up with a threat of unsettled weather by later in the period.

Friday January 29 2021 Forecast (7:53AM)

DAYS 1-5 (JANUARY 29- FEBRUARY 2)

A frigid Friday for us as a large ocean storm pulls arctic air down out of Canada right across New England. Also, we have the snow threat for eastern areas as a result of a trough swinging around the back side of a large ocean storm. While this event will be short-lived, occurring from north to south over a 2 to 4 hour period this afternoon, it can produce some significant snowfall in a brief time, especially over Cape Cod, along with a lot of wind, so brief blizzard conditions may occur especially for the outer Cape which is likely to be in the heaviest of the snowfall combined with the steadiest/strongest wind. Other than a few additional ocean-effect flurries for Cape Cod tonight into early Saturday, by later today the snow threat is gone and it’s just cold and dry into the weekend, although the core of the cold will have departed and we’ll see an abatement of the wind as well. By Sunday, even though we’ll still be below freezing, it will feel mild in comparison to what we’ll be going through today. And then our attention turns to the early week storm threat. There is not all that much to say yet, other than the threat is there, and the timing for our area looks like later Monday night and Tuesday at this time. The potential is increase for a significant snowfall from this event, but it’s too early to know if a rain/snow line will be involved and far too early to really talk about snow amounts. These details will become clearer as we progress into and through the weekend. In the mean time, stay warm!

TODAY: Variably cloudy. A period of snow showers/squalls moving north to south across NH Seacoast and eastern MA this afternoon, heaviest Cape Cod, accumulations of a coating to 1 inch I-95 belt, 1-3 inches Cape Ann & MA South Shore, 3-6 inches Cape Cod. Highs 14-21. Wind N 15-25 MPH, higher gusts. Wind chill below zero at times.

TONIGHT: Clouds and additional snow showers Cape Cod, clear elsewhere. Lows 5-12. Wind NW 10-20 MPH, higher gusts. Wind chill below zero.

SATURDAY: Sunny. Highs 18-25. Wind NW 5-15 MPH, higher gusts. Wind chill occasionally below 10.

SATURDAY NIGHT: Clear. Lows 0-7 except 8-15 urban centers. Wind NW 5-15 MPH, diminishing. Wind chill occasionally below zero.

SUNDAY: Mostly sunny. Highs 25-32. Wind variable up to 10 MPH.

SUNDAY NIGHT: Increasing high clouds. Lows 15-22. Wind N up to 10 MPH.

MONDAY: Thickening overcast. Highs 25-32. Wind NE 5-15 MPH.

MONDAY NIGHT: Overcast. Snow arriving. Lows 20-27. Wind NE 5-15 MPH.

TUESDAY: Overcast. Snow likely, mix/rain possible. Highs 28-35. Wind NE 10-20 MPH, higher gusts.

DAYS 6-10 (FEBRUARY 3-7)

Fair, breezy, briefly colder February 3 post-storm. Temperature moderation follows later next week with some unsettled weather returning in around mid period as the next low pressure area tracks north of the region, with drier/colder air following that.

DAYS 11-15 (FEBRUARY 8-12)

The overall pattern may quiet down but there remains a lot of uncertainty due to the questions surrounding the status of blocking, which should be much weaker. Will re-evaluate this period over the next few days.

Thursday January 28 2021 Forecast (7:40AM)

DAYS 1-5 (JANUARY 28- FEBRUARY 1)

We will continue to be impacted by the evolution of a large ocean storm to the south and east of New England through Friday, first causing a couple more episodes of snow showers then helping to pull in the coldest air of the season Friday into the start of the weekend, as previously discussed. Also as previously discussed we will see an easing of the cold late in the weekend and a storm threat for early next week. It’s obviously still too early for details on that threat but by the end of this forecast period (Monday February 1) we’ll be awaiting the arrival of that system, which will be off the Mid Atlantic Coast by then, having redeveloped from a system moving into the Ohio Valley. There will be lots to talk about over the coming days…

TODAY: Mostly cloudy with snow showers likely in the morning, especially from southeastern NH through eastern MA, accumulating up to 1/2 inch in spots but local accumulation of up to an inch or two possible Cape Ann and MA South Shore. Partly sunny with scattered snow showers favoring Cape Cod during the afternoon. Highs 28-35. Wind NE to N increasing to 10-20 MPH with higher gusts late in the day.

TONIGHT: Partly cloudy with snow showers Cape Cod. Clear elsewhere. Lows 8-15. Wind N 15-25 MPH, higher gusts especially eastern coastal areas. Wind chill below zero at times.

FRIDAY: Mostly sunny to partly cloudy with most clouds eastern MA coastal areas especially Cape Cod. Additional snow showers possible mainly Cape Cod but brief snow showers/squalls possible from north to south in southeastern NH and eastern MA midday or afternoon, accumulation of a coating to 1 inch with locally up to 2 inches possible. Highs 15-22. Wind N 15-25 MPH, higher gusts. Wind chill near zero at times.

FRIDAY NIGHT: Clear. Lows 6-13. Wind NW 10-20 MPH, higher gusts. Wind chills below zero.

SATURDAY: Sunny. Highs 20-27. Wind NW 5-15 MPH, higher gusts. Wind chills near to below 10 at times.

SATURDAY NIGHT: Clear. Lows 0-7 except 8-15 urban centers. Wind NW 5-15 MPH, diminishing.

SUNDAY: Mostly sunny. Highs 26-33. Wind variable up to 10 MPH.

SUNDAY NIGHT: Increasing high clouds. Lows 15-22. Wind N up to 10 MPH.

MONDAY: Thickening overcast. Chance of snow by late-day. Highs 25-32. Wind NE 5-15 MPH.

DAYS 6-10 (FEBRUARY 2-6)

Storm likely to impact the region February 2 with precipitation type to be determined. Dry, colder February 3. A temperature moderation follows with the next threat of unsettled weather later in the period. This evolution will be the result of a weakening blocking pattern.

DAYS 11-15 (FEBRUARY 7-11)

Blocking pattern may remain somewhat in place but should be weaker along with more high pressure ridging in the US Southeast. A lot of uncertainty in our day to day weather as a result but we may be impacted by unsettled weather early and again late in the period.

Wednesday January 27 2021 Forecast (7:42AM)

DAYS 1-5 (JANUARY 27-31)

One final area of synoptic snowfall associated with energy from low #1 (see yesterday’s discussion) is producing small additional snowfall accumulation in a much of the region this morning. This energy will slide offshore by midday as low #2 will have taken over well south of the region, but a northeasterly air flow will bring some low level moisture in from the Atlantic and create showers of snow and/or rain during the day today, and a few other potential snow showers tonight into Thursday as low #3 emerges off the Mid Atlantic Coast and intensifies into a large ocean storm, which will track well southeast of New England through Friday. But as it turns to the north on Friday we will see a trough behind it try to swing through with one additional snow shower or snow squall chance on Friday, although most of this activity will likely stay just offshore or impact Cape Cod. What it will do is pull the coldest air of the season so far into our region Thursday night through early Saturday, before temperatures recover a little more by later in the weekend as high pressure builds in and the low moves away…

TODAY: Mostly cloudy. Periods of snow with up to 1/2 inch additional accumulation through mid morning, then scattered snow showers except rain or snow showers in coastal areas. Highs 30-37. Wind N-NE 5-15 MPH.

TONIGHT: Mostly cloudy. Scattered snow showers favoring eastern coastal areas with localized additional small accumulations. Lows 23-30. Wind NE 5-15 MPH.

THURSDAY: Mostly cloudy with snow showers likely in the morning, accumulating up to 1/2 inch in spots but local accumulation of up to an inch or two possible Cape Ann and MA South Shore. Partly sunny with scattered snow showers favoring Cape Cod during the afternoon. Highs 28-35 by midday but temperatures falling sharply later. Wind NE to N increasing to 15-25 MPH.

THURSDAY NIGHT: Partly cloudy with snow showers Cape Cod. Clear elsewhere. Lows 8-15. Wind N 15-25 MPH, higher gusts especially eastern coastal areas. Wind chill below zero at times.

FRIDAY: Mostly sunny to partly cloudy with most clouds eastern MA coastal areas especially Cape Cod. Additional snow showers possible mainly Cape Cod but brief snow showers/squalls possible from north to south in southeastern NH and eastern MA midday or afternoon. Highs 16-23. Wind N 15-25 MPH, higher gusts. Wind chill near zero at times.

FRIDAY NIGHT: Clear. Lows 6-13. Wind NW 5-15 MPH.

SATURDAY: Sunny. Highs 20-27. Wind NW 5-15 MPH.

SATURDAY NIGHT: Clear. Lows 0-7 except 8-15 urban centers. Wind NW 5-15 MPH, diminishing.

SUNDAY: Mostly sunny. Highs 26-33. Wind variable up to 10 MPH.

DAYS 6-10 (FEBRUARY 1-5)

Watching a storm potential for early next week (February 1-2) depending on the evolution of a low pressure area moving into the Ohio Valley then redevelop along the northern Mid Atlantic Coast. There are a lot of scenarios on the table for this ranging from a graze to a significant snowstorm to a storm that includes a variety of precipitation. Don’t pay attention to any model snowfall numbers without knowing the uncertainty. Fair, seasonably chilly weather follows this for the middle of next week and then expecting a temperature moderation toward the end of next week. This evolution will be the result of a weakening blocking pattern.

DAYS 11-15 (FEBRUARY 6-10)

Blocking becomes very weak to non-existent and we see a little but more ridging in the US Southeast. For us, looks like a milder pattern evolves and there will be a threat of some unsettled weather in the February 6-8 window. Also keep in mind that a “milder pattern” does not mean mild every day nor does it automatically mean that unsettled weather means “rainstorms”. We still have to be general beyond a few days and look at each situation in an objective and scientific fashion as it draws closer so we can make the best forecast possible.