Snow is On the Way

After several days of media hype, and people posting model forecasts for extreme amounts of snow on social media, it looks like we do actually have a snowstorm on the way, and it could be a decent-sized one for parts of the region.

High pressure over Ontario and low pressure over Texas are two things we need to pay attention to for the next day or two. Image provided by NOAA.

Low pressure over Texas this afternoon will combine with a second area near the Texas coast to become a single storm system later today, which will then head northeastward into the Tennessee Valley tonight, bringing plenty of moisture with it from the Gulf of Mexico. Meanwhile, a strong high pressure system is moving across southeastern Canada, bringing plenty of cold air into the Northeast. When you get copious amounts of moisture running into cold air, you end up with snow, potentially a lot of it,. That’s what’s going to happen here late Wednesday into Thursday.

Winter Storm Watches are in effect for all of Southern New England. Image provided by Pivotal Weather.

That low pressure area will move from the Tennessee Valley to the Mid-Atlantic coastline on Wednesday before moving offshore and passing south of New England. While there are still some questions as to the exact track it will take, which has implications for the forecast itself, the models have come into better agreement today on a more northerly track than they were showing last night. This has several implications for the forecast around here:

1. Snow will likely penetrate even farther inland, with heavier snow farther inland as well.
2. Rain/snow ratios will be lower across southeastern New England, resulting in a wetter snow.
3. A change to sleet or rain is now possible across Cape Cod, and possibly parts of southeastern Massachusetts and southern Rhode Island.

We mentioned in our Weekly Outlook that there would likely be a sharp cutoff in the northern extent of the snow, going from heavy snow to little snow in a short span, but we weren’t sure where that cutoff would set up. At this point, it’s looking more and more likely that it will set up somewhere in central or southern New Hampshire, meaning that most of us will be shoveling by Thursday morning. This detail is still not definite, so obviously things can change in the next 24 hours or so.

Plenty of cold air will be in place before the storm moves in. Image provided by Weathermodels.com

That high pressure area in southeastern Canada will provide us with plenty of cold air, which will be evident tonight when temperatures drop into the teens or even single numbers. As the snow moves in Wednesday night, we’ll see a coastal front setup across eastern Massachusetts and Rhode Island. This is a common occurrence in winter storms. Basically, the northeast to east winds off the water send temperatures up to the lower to middle 30s along the coast and a short distance inland (anywhere from 20-40 miles). On the other side of that front, northeast to north winds keep the colder air locked in, with temperatures in the teens and lower 20s. Obviously, in the “milder” air on one side, you’ll get a wetter snow, with the possibility of some mixed precipitation, while the colder area gets mostly snow that is more powdery. We said “mostly snow”, as you can get some milder air aloft which could allow for some sleet to mix in, which obviously would have a significant impact on snow accumulations. That coastal front will eventually collapse southeastward toward the coast as the low pressure area moves by, allowing the colder air to eventually move back in everywhere, and any mixing that does take place eventually goes back over to all snow.

The snow to rain ratio varies by temperature, as this chart shows. Image provided by Weathertrends360.com

As for the timing, most of Wednesday should be fine, so you can do any errands that need to be completed before the storm moves in. Snow should move into the South Coast towards the evening rush, quickly spreading northward, reaching the MA/NH border by midnight. Snow may fall moderate to heavy at times overnight, with some mixing possible across Cape Cod and the Islands (and possibly southeastern Massachusetts) late at night and early Thursday morning. Most of the steady precipitation should wind down by midday, but some lingering snow showers are possible, especially along the coast, through the afternoon.

Snow isn’t the only threat with this system, as gusty winds are also expected, especially along the coastline. While this storm won’t be that strong, at least compared to many winter storms in the past, the gradient between it and the large high pressure area to the north will create some gusty winds. Sustained winds of 15-25 mph, with gusts to 40 mph or more, are likely. These gusty winds may enhance the snow across parts of eastern Massachusetts. However, with high astronomical tides, the winds may also result in some coastal flooding around high tide, especially at northeast and east facing coastal areas.

Wind gusts to 40 mph or more are possible, especially along the coast. Image provided by WeatherBell.

So, how much snow are we looking at? Obviously, there’s still some things that complicate this part of the forecast (snow ratios/mixing/northern extent of the snow), so this is preliminary for now, and we may adjust it tomorrow if needed, but here’s our thinking:

Central New Hampshire: 2-4″
Southern New Hampshire/Seacoast: 4-8″
Merrimack Valley/Central Massachusetts: 5-10″
North Shore/MetroWest/Metro Boston: 6-12″
Interior Southeastern Massachusetts/Rhode Island: 8-14″
Cape Cod and the Islands: 4-8″

This model is probably closest to our thinking on snow accumulations at the moment. Image provided by Pivotal Weather.

Colder air will settle back into the region behind the storm for Thursday night and Friday, so you’ll want to clear out the driveways and walkways before everything freezes solid.

Weekly Outlook: December 14-20, 2020

Hope you enjoyed the 60-degree temperatures on Sunday, because changes are coming. It’s going to snow this week, likely more than once for many of us.

Sunday was a mild day across most of the region. Image provided by NOAA.

A cold front moved across the region overnight and is now south of us. Low pressure will move off the Mid-Atlantic coastline and ride along that frontal system today. Precipitation will move in towards midday and continue through the afternoon, ending in the evening. Temperatures will be near or above freezing, so we’ll see a mix of rain and snow, likely changing over to snow before ending in many areas as colder air filters in behind the system. We’re not expecting much accumulation, mainly an inch or so, and mainly south of the Mass Pike. A few places could see up to 2 inches in heavier bursts, but overall this isn’t a big deal. However, since it will fall during the afternoon, it could make a mess of the afternoon commute, so keep that in mind if you are not working from home. North of the Mass Pike, we’re only looking at some flurries, if that, with the ground getting coated in some locations.

Not much snow is expected today, but the timing will make it a bit more impactful. Image provided by WeatherBell.

That storm will move into Atlantic Canada on Tuesday, and strengthen into a powerful storm system. Gusty northwest winds behind the storm will usher much cooler air in for Tuesday and Wednesday as high pressure moves into southeastern Canada. This will become important as we head into later Wednesday and Thursday as the next storm system moves towards the area.

Wednesday morning could be rather chilly across the region. Image provided by Weathermodels.com

As you’ve no doubt heard by now, a rather strong storm system will impact the East Coast later Wednesday into Thursday. With high pressure to the north, we’ll have plenty of cold air in place, so anything that does fall will almost certainly fall in the form of snow. As the storm strengthens, it will produce gusty winds in some areas, which combined with the high astronomical tides, could result in some coastal flooding, especially east and northeast-facing locations. Beyond that, there’s a lot of uncertainty. That storm that moved into Atlantic Canada will not move too much, and it will have an impact on the track our mid-week storm takes. Another factor will be the high pressure area to our north. It will try to send cool and dry air southward into the region. This will likely result in a sharp cutoff of the precipitation, going from heavy snow to virtually no snow over a relatively small area. Where that cutoff sets up is also still in question. The models, while in general agreement that a powerful storm will move off the Atlantic Coast and south of New England, differ on some of the finer details, which have an enormous impact on the forecast. It’s still WAY too early to pin down any specifics, so we won’t bother to attempt it. We’ll just say that the potential exists for a significant snowstorm across the region from late Wednesday into Thursday. Beyond that, we’ll offer more details in a special blog post on Tuesday.

Differences among the models can have a big impact on the forecast for the storm around here. Images provided by Pivotal Weather.

Behind the storm, high pressure builds back in for Friday and Saturday with dry and chilly conditions. If there’s fresh snow on the ground, some places could get quite chilly at night, especially Thursday night and Friday night. By Sunday, the high moves offshore and temperatures will start to moderate. However, another system may bring in some rain or snow. We’ll worry about that one after we get through the first two.

Monday: Cloudy with rain or mixed precipitation developing around midday, eventually changing to light snow by late afternoon. High 32-39.

Monday night: Light snow ends in the evening, then skies clear out overnight. Low 23-30.

Tuesday: Sunshine and some afternoon clouds, breezy. High 28-35.

Tuesday night: Clear during the evening, clouds move in late at night. Low 12-19.

Wednesday: Cloudy and becoming breezy with snow possible late in the day and at night. High 24-31.

Thursday: Cloudy and windy with snow likely, ending during the afternoon. High 24-31.

Friday: Partly to mostly sunny. High 27-34.

Saturday: Sunny in the morning, clouds return in the afternoon. High 30-37.

Sunday: Cloudy with a chance of rain or snow. High 37-44.

Stormy Saturday on Tap

The first snowstorm of meteorological winter is expected across at least part of the region on Saturday.

Low pressure is moving into Tennessee this afternoon, on its way toward the Northeast. Image provided by the Weather Prediction Center.

Low pressure moving into the Tennessee Valley this afternoon will cross the Appalachians tonight and move off the Mid-Atlantic coastline on Saturday. Ahead of it, rain will move into our area tonight, and it could be heavy Saturday morning. Given our long-term rainfall deficit, this is a good thing. However, some localized flooding is possible, especially in areas where the storm drains are covered or clogged by fallen leaves. This is the easy part of the forecast.

Rainfall totals of 1-2 inches are possible across much of the area from this storm. Image provided by Weathermodels.com

As the system moves northeastward, an upper-level disturbance will drop southeastward from Canada. This disturbance and the system to the south will eventually phase, resulting in a fairly strong storm system off the East Coast. There is still some question to the exact track the system takes, but it will likely pass close to or just south of Cape Cod and the Islands. As the system intensifies, it will generate some strong winds, especially along the coast south of Boston. High Wind Watches have been posted along the coast in this area, where sustained winds of 25-35 mph are expected, with some gusts to 50 mph or more possible.

Wind gusts of 50 mph or higher are possible along the coast late Saturday and Saturday night. Image provided by WeatherBell.

As the storm passes by our longitude, it will turn winds from the northeast to the north and eventually northwest. This will help bring colder air down from the north. The airmass to the north isn’t that cold by December standards, but temperatures will drop below freezing, which will allow for the rain to change over to snow from northwest to southeast as the low passes by. The exact track of the storm will determine exactly where the rain/snow line ends up. A track farther to the north and west results in less snow to the south and east.

The models still have a wide variety of ideas for how much snow is expected and where it will fall. Images provided by Pivotal Weather.

When that changeover occurs also will have a big impact on the snowfall amounts. Right now, here’s our thoughts on the changeover timing:

Late morning: The higher terrain from central Massachusetts into southwestern New Hampshire
Midday/Early Afternoon: Southern New Hampshire
Early/Mid Afternoon: Merrimack Valley and New Hampshire Seacoast
Late Afternoon: MetroWest and the North Shore as well as Northern Rhode Island
Early Evening: I-95 corridor from Boston to Providence and parts of Southeastern Massachusetts.

Everything should wind down and end by midnight as the storm moves into the Gulf of Maine and pulls away from the area.

Beyond the timing and track issues, we have one more thing that complicates the snowfall forecast. As the system gets cranked up, bands of very heavy snow will develop. Some of these bands may produce 1-2 inches of snow in an hour. Exactly where those bands set up is nearly impossible to determine in advance, and even trying to figure out a general area for them is tough, because part of it will depend on the track of the system.

Having said all of that, here’s our best estimate right now for snowfall:

Dusting (if that): Cape Cod and the Islands
1-2″: Southeastern Massachusetts and Southern Rhode Island
2-4″: I-95 corridor from Boston to Providence
3-5″: Northern Rhode Island/MetroWest/North Shore/New Hampshire Seacoast
4-7″: Merrimack Valley/Southern New Hampshire
5-9″: Worcester County/Southwestern New Hampshire

Obviously this is a low-confidence forecast, based on all of the factors above, but it’s our best guess at the moment. If there’s any significant changes, we may do another quick update Saturday morning/early afternoon.

The next few days after the storm look calmer, but another system will develop off the East Coast on Tuesday. Right now, it looks like it will stay too far south and east to have any impacts here, but we’ll keep an eye on it.

Weekend Outlook: December 4-7, 2020

It looks like we’ve got some snow coming in this weekend for at least part of the region, but that’s only part of a complex forecast for the next few days.

High pressure will slide offshore later today and tonight while clouds start to stream in ahead of a cold front. That front may produce a few showers on Friday, but most of us will just see some clouds as the front moves through. However, this will set the stage for the next storm.

Enjoy the mild weather on Friday, because changes are coming. Image provided by Weathermodels.com

Low pressure currently near the Louisiana coastline will head northeastward tonight, moving up the Appalachians on Friday, then off the Mid-Atlantic coastline on Saturday. At the same time, an upper-level disturbance in Canada will dive southeastward. As these two systems meet up or “phase”, they will create a strengthening low pressure system. The track of that low will determine several things, but the two main ones are how much precipitation will fall, and whether it will be rain or snow. Most of the models bring the storm near Cape Cod or just south of it, but there are others that bring it across southeastern Massachusetts. The farther north and west the low travels, the farther north and west the rain/snow line ends up.

There are still some significant differences among the models for the weekend storm. Images provided by Pivotal Weather

Before we get too far ahead of ourselves, let’s get to what we are fairly sure about. Rain will develop across the region early Saturday morning, and may fall heavy at times during the day on Saturday. This will help put another dent in our long-term rainfall deficit. As the low passes by, northerly winds will bring cooler air into the region. There’s not a lot of “cold” air to begin with, but temperatures will likely drop to near or below freezing, which will allow for a changeover to snow, at least north and west of Boston. That changeover is likely to occur Saturday night, but at least one model has it change over much earlier – during the afternoon. Others only have the changeover occur as the precipitation winds down and ends Sunday morning, and at least one other doesn’t have it changeover at all. Obviously when that changeover occurs will have an impact on how much snow (if any) accumulates.

Whether it’s all rain or rain to snow, this will be another heavy precipitation producer. Image provided by WeatherBell.

Right now, we’re expecting a change to snow from northwest to southeast Saturday evening and night, with everything winding down around daybreak Sunday. The snow could be heavy at times during Saturday evening, but should taper off at night as the system starts to pull away. Several inches could accumulate well north and west of Boston, but this is still a bit uncertain. We’re not going to forecast any amounts yet, as there’s not enough confidence yet to come up with specific amounts. We’ll do another blog post just on the storm tomorrow, and at that point we’ll have a specific snowfall forecast.

Skies should start to clear out Sunday afternoon as gusty west to northwest winds will bring drier air in behind the storm. High pressure will start to build in on Monday, but with an upper-level low pressure system moving through, we’ll still have some clouds, and a few rain or snow showers are possible.

Thursday night: Becoming mostly cloudy. Low 32-39.

Friday: Mostly cloudy, becoming breezy, chance for a few showers, mainly south of the Mass Pike during the afternoon. High 49-56.

Friday night: Cloudy with some showers developing. Low 35-42.

Saturday: Cloudy and windy with rain, heavy at times, changing to snow from central Massachusetts into southern New Hampshire late in the day. High 39-46 early (47-54 across Cape Cod and the Islands), then temperatures drop during the afternoon.

Saturday night: Cloudy and windy with rain changing to snow from northwest to southeast before tapering off and ending toward daybreak. Low 25-32, a little milder across Cape Cod and the Islands.

Sunday: A few lingering rain or snow showers early, then clearing in the afternoon, breezy. High 33-40.

Sunday night: Clear to partly cloudy. Low 19-26.

Monday: A mix of sun and clouds, slight chance for a rain or snow shower. High 32-39.

Stormy Weather Ahead for the East

A rather potent storm system will bring a variety of weather to the eastern third of the United States over the next few days.

Low pressure is developing along a frontal system in southern Texas this evening. Image provided by the Weather Prediction Center.

Low pressure developed along a frontal system in southern Texas on Saturday, and it will slowly strengthen as it moves northeastward tonight and Sunday. As it strengthens, it will draw moisture northward from the Gulf of Mexico, while colder air continues to move southward behind the storm system. This will set the stage for a couple of rather active days across the Eastern third of the nation, with several different types of weather likely.

The GFS model shows the progression of the storm over the next few days. Loop provided by Tropical Tidbits.

The biggest threat initially will be severe weather. As the warm, moist air flows northward from the Gulf of Mexico and clashes with the colder air moving in behind the storm, strong to severe thunderstorms are possible. A few storms are possible overnight in parts of Texas and Louisiana, but the threat will shift into the Gulf Coast on Sunday, parts of the Southeast and the Carolinas Sunday night, and parts of the East Coast from Florida to the Mid-Atlantic states on Monday. Some of the stronger storms may produce heavy downpours, damaging winds, and possibly some tornadoes.

Strong to severe storms are possible from the Gulf Coast into the Carolinas on Sunday. Image provided by Pivotal Weather.

While severe weather is not common at this time of year, it is certainly not unheard of. In fact, Saturday marked the 32nd anniversary of one of the strongest tornadoes on record to hit North Carolina. On November 28, 1988, an F4 tornado tore an 84-mile path of damage across parts of North Carolina, including the city of Raleigh.

As the storm moves up the Appalachians it will bring unseasonably mild air to the East Coast, but also some heavy rainfall. Temperatures will be in the 60s and 70s across the Gulf Coast and Southeast on Sunday. By Monday, 60-degree readings will be possible as far north as southern New England, with some 70s into the Carolinas and parts of southern Virginia. The mild air may linger into Tuesday across parts of New England as well. While these temperatures are 10-20 degrees above normal, they will likely fall short of the record highs in most locations.

Monday will be a warm day by November standards up and down the East Coast. Image provided by WeatherBell.

The warm weather will be transported in by strong southerly winds ahead of the system. Sustained winds of 25-35 mph will be common up and down the East Coast. Many places could see wind gusts of 50-60 mph or stronger, which could lead to power outages as trees and wires come down.

Wind gusts in excess of 50 mph are possible across the East Coast ahead of the storm. Image provided by WeatherBell.

In addition to the warm weather, heavy rain is likely for much of the East. The warm, moist air being drawn northward from the Gulf of Mexico will be deposited up and down the East Coast later Sunday into Monday, and early Tuesday for parts of New England. Rainfall totals of 1-2 inches will be common, with some places possibly picking up 3 inches or more, especially in parts of eastern New England. While this will help put another significant dent in the long term drought that the region is experiencing, too much rain at once will likely lead to flooding in some areas.

Heavy rain is likely across the East Coast Monday into Tuesday. Image provided by Weathermodels.com

While all of this is going on ahead of the storm, a different scenario will be evolving on the storm’s back side. Colder air flowing southward from Canada will clash with the warm air, resulting in snow across parts of the Great Lakes and the Appalachians. The snow will be accompanied by gusty winds, lowering visibility in many locations, resulting in very hazardous driving conditions. While the snow won’t be exceptionally heavy, many places could receive upwards of 4-8 inches by the time everything winds down. Across the higher elevations of the Appalachians, even into the southern Appalachians, some heavier amounts are possible as well. As the systems gets caught under an upper-level low pressure system in southeastern Canada, it may produce some lake-effect snow into mid-week downwind of Lakes Erie and Ontario.

Accumulating snow is expected behind the storm system. Image provided by Pivotal Weather.

Once this system pulls away, things will quiet down across the East for a few days, but there are signs that another system could impact parts of the East next weekend.

Record Heat and Cold, Snowstorms, Droughts, and Tropical Storms – What’s Next?

September is when we start to transition from Summer to Winter, but this September is starting off with a bang.

Intense heat has been common across much of the West for the past few days. Temperatures well over 100 degrees were widespread during Labor Day Weekend, especially across California, with numerous records set. One location, Richmond, on the eastern side of San Francisco Bay, reached 107 degrees Monday afternoon, tying their all-time record, originally set on September 15, 1971. Several other locations set monthly records for September as well. The worst of the heat has passed, but it will remain hot on Tuesday, with highs likely topping 100 across much of interior California and the Desert Southwest, possibly setting a few more records. Temperatures should gradually cool down a little more as we get toward the middle and latter portion of the week.

Another hot day is likely across interior California on Tuesday. Image provided by WeatherBell.

Heat was also common across the Plains and Rocky Mountains over the weekend, but big changes are developing thanks to a strong cold front. Denver set a record high of 97 on Sunday, then reached 93 on Monday. On Tuesday, that 93 will get reversed, with a daytime high closer to 39 (The high for the calendar day will be the 46-degree reading at midnight). On top of that, accumulating snow is likely. Even by Denver standards, this is quite early in the year for snow. Their all-time record for earliest snow is September 3, 1961, but on average Denver doesn’t see its first flakes until October 18. This won’t be the 1st time that Denver hit 90 one day and then had measurable snow the next. On September 12, 1993, Denver recorded a high of 92 degrees, and on September 13, they had 5.4″ of snow.

While a few inches of snow are likely in Denver and onto the adjacent High Plains of eastern Colorado and western Nebraska, heavier snow is likely across the mountains on Colorado and Wyoming. Across the higher elevations, snowfall totals in excess of a foot are likely. While the snow will likely last a while in the mountains, at the “lower” elevations on the Plains, it will disappear quickly. High temperatures in Denver will be back into the 60s by Friday, and near 80 by the end of the weekend.

Heavy snow is likely in the higher elevations of the Rockies. Image provided by the College of DuPage.

While the snow will get a lot of the headlines, the cold air behind the front will be making headlines of its own. The first frost and freeze of the season is likely across parts of the Dakotas, Montana, and northern Minnesota Tuesday and/or Wednesday morning, with lows in the upper 20s and 30s. The cold air will continue to push southward across the Great Plains during the day on Tuesday, with numerous record lows expected Wednesday morning as far south as the Texas Panhandle. The cold air will eventually spread eastward, but will be modified significantly before it reaches the Eastern United States.

Record lows are likely across the Plains and the Rockies Wednesday morning. Image provided by Weathermodels.com

While plenty of (frozen) precipitation is expected across the Rockies, the lack of precipitation is causing problems across the Northeast, specifically New England. Aside from a few showers with a cold front on Thursday, generally dry weather is expected across much of New England this week, and things don’t look that promising for much of next week either. This shouldn’t be a surprise, as precipitation has been generally below to well below normal across the region since the Spring. In some areas, the amount of rain has only been around 50-60% of normal since April 1. Drought conditions have developed across nearly all of New England, and for a good portion of the region, it is now considered a severe drought. What the region needs is a series of systems that can produce moderate rainfall to help alleviate the drought (too much at once won’t help that much), but prospects for that aren’t promising at this time. In fact, rainfall looks to remain below normal for much of the remainder of September.

Drought conditions are worsening across New England. Image provided by the National Drought Mitigation Center.

Meanwhile, as we approach the climatological peak of hurricane season, the Atlantic is once again getting more active. Tropical Storms Paulette and Rene both developed on Monday in the central and eastern Atlantic respectively. Paulette is expected to remain a tropical storm for the next several days while remaining over open water. It is not expected to be a threat to land. Meanwhile, Tropical Storm Rene moved into the Cabo Verde Islands Monday night and early Tuesday, producing heavy rain and gusty winds. It will likely strengthen over the next couple of days, possibly becoming a hurricane later this week. Once it pulls away from the Cabo Verde Islands, it is also expected to remain over open water for much of this week, presenting no additional threat to land.

Satellite loop showing Tropical Storms Paulette and Rene in the central and eastern Atlantic. Loop provided by Tropical Tidbits.

Those systems aren’t the only ones in the Atlantic that are being watched. An area of low pressure a couple of hundred miles west-southwest of Bermuda is expected to drift westward or northwestward over the next day or two. Some development of the system is possible. It may bring some rainfall into parts of the Carolinas and Southeast later this week. The other area that is being watched isn’t immediately apparent right now, as it is still over western Africa. A tropical wave is expected to emerge from the west coast of Africa later this week. Forecast models show the potential for this wave to develop rather quickly once it moves into the Atlantic. It could threaten the Cabo Verde Islands over the weekend.

The peak of hurricane season is during the middle to latter half of September. Given how active this season has been so far, there will likely be more systems developing. There are only 4 names left on this list for this season – Sally, Teddy, Vicky, and Wilfred. Once the list is exhausted, the Greek alphabet is used. This has only happened once before – in 2005. During that season, there were 28 named storms of which 15 became hurricanes.

A Chilly Weekend is Coming, a Little Snow too?

By now, you’ve heard the TV meteorologists talking about how it’s going to snow, or you’ve read the headlines about an “historic May snowstorm” that’s coming. As usual, we at Storm HQ will avoid the hype and just give you the facts. Yes, there will be some snowflakes around here and no, it won’t be a big deal at all.

A cold front is moving across the Great Lakes this afternoon, and it move across our area tonight, with plenty of clouds and possibly a few showers. Behind that front, much colder air will start to move into the region. This is an anomalously cold airmass for early May, and in fact, is more representative of early March. That front is expected to stall out near the South Coast, and then a wave of low pressure will develop along the front and ride along it, crossing southern New England Friday night and early Saturday.

The ECMWF model shows the progression of the system for Friday into Saturday. Loop provided by Pivotal Weather.

We’ll have some rain moving in Friday afternoon and evening, but as the sun sets and temperatures drop, some wet snow will start to mix in. The most likely spots for snow are in the hilly terrain from northern Rhode Island across Worcester County and into the Monadnocks of southwestern New Hampshire, as well as out in the Berkshires. However, we wouldn’t be surprised if there was some wet snow mixed in with the rain even into the suburbs of Boston.

As we mentioned with the last few storms, it’s awfully tough to get accumulating snow into early May for a variety of reasons. For one, the ground is fairly mild. Any accumulations will be mainly on grassy surfaces, as pavement temperatures are much too warm now. Secondly, temperatures may not even drop to freezing, but could stay in the middle to upper 30s. Third, the intensity of the precipitation will be key. Heavier precipitation will bring down colder air from aloft, resulting in the change to snow, whereas light precipitation will tend towards more rain.

As far as accumulations, as we said, we’re not expecting this to be a big deal for most of us. You may wake up Saturday morning, if you’re up early enough, to see a little bit of a coating on grassy surfaces, decks, and car roofs/windshields. As we mentioned, most of the accumulations will be confined to the hilly terrain, where a few inches could fall.

Snow is fairly rare once you get into May. Using data for Lowell, snow has been recorded 5 times during the month of May over the past 92 years, and measurable snow only twice.

5/11/1945 – Trace
5/1/1953 – Trace
5/10/1977 – 2.6″
5/6/1996 – Trace
5/18/2002 – 1.0″

The ECMWF model is closest to our thinking for snowfall with this storm. Image provided by WeatherBell.

The snow is only part of the story though, and in fact, a minor part. As the storm intensifies while pulling away on Saturday, gusty winds are expected across the area. West winds of 15-25 mph with gusts of 40-50 mph are expected, especially along the coast. At the same time, an upper-level low pressure area will be moving into the region, bringing in very cold weather. That upper low may trigger a few rain or snow showers in the afternoon, but the cold temperatures will be the story. High temperatures likely will stay in the 40s, which may set records for the lowest high temperatures for the date in many locations.

Record low high temperatures are possible across parts of the region on Saturday. Image provided by Weathermodels.com

The really cold weather will be short-lived, as we will start to moderate on Mother’s Day as high pressure builds in. However, if you’re hoping for some sustained warmth, it’s not coming anytime soon. There are some hints that we may get out of the pattern that’s kept us quite chilly for most of April and early May in another 10 days or so, but a “warm” pattern is still a ways off.

Temperature forecast for the next 45 days for Bedford, Massachusetts based on the 51 members of the ECMWF Ensemble forecast. Image provided by Weathermodels.com

The image above is the high and low temperature forecast for Bedford for the next 45 days, based on the ECMWF Ensemble, which has 51 separate members. The solid red and blue lines in the middle of each graph are the “normal” highs/lows for each day. The green dot is the average of the 51 members for each day (which is also represented numerically in the middle of the 2 charts), and the shaded gray area is the area that between 1/4 and 3/4 of the members fall. The horizontal blue lines above and below that are the extreme on each day. As you can see, this model is forecasting temperatures to remain well below normal through May 14-15. After that, temperatures generally average near or a little below normal until June 9. Granted, “normal” for those dates is upper 60s to near 70 for high temperatures, so it’ll be milder, but still a little cooler than we should be. Finally, we get to near or a little above normal for a sustained period around June 10. Now this is just one model, so take it with a grain of salt, but it’s done fairly well diagnosing the general details of our weather pattern for several weeks now. There is hope that you can finally take your summer clothes out of storage, perhaps as early as next weekend.

Snowy Saturday Morning

Yes, snow is still on the way, and this is an update to our forecast, but it really hasn’t changed that much.

Low pressure will move out of the Ohio Valley today, passing south of New England early on Saturday. We’ll have some cold air in place, so many of us will have some snow Saturday morning, but don’t worry, it won’t be a lot, and it won’t hang around for too long.

The precipitation will move in around midnight, and it will likely start as rain for most of us, with temperatures still in the upper 30s to lower 40s. However, it will quickly change over to snow as temperatures drop into the middle 30s. It looks like there may be a burst of moderate to heavy snow overnight, especially along and south of the Massachusetts Turnpike. A change back to rain is expected towards daybreak, except in the hills from northern Rhode Island into Worcester County and the Monadnocks in southwestern New Hampshire.

The GFS model shows the progression of snow and rain across the region. Loop provided by WeatherBell.

As we mentioned yesterday, it’s awfully tough to get accumulating snow in mid-April for a variety of reasons, but there are some things that will help this time. First of all, most of the snow will fall at night. Once the sun comes up, the sun angle is similar to late August, so once we get past about 7-8am, even if there are still flakes falling, there won’t be any more accumulation. Second of all, temperatures will be close to freezing. Third, the snow may come down at a decent clip, which will help bring down a little bit of colder air from aloft. Working against accumulating snow is the fact that the ground is warm. Any accumulations will be mainly confined to grassy surfaces, as the pavement is considerably warmer. There may be a little slush on paved surfaces, but not much. Also, we’re not going to have a large window of time for accumulating snow. As we said, the precipitation will start as rain around midnight before flipping to snow. Once it does start snowing, it will take a little time to start accumulating, due to the wet/warm ground. That will take until 1-2am, and by 7am, the daylight will help put an end to accumulations. So, we’ve really only got about 5-6 hours of accumulating snow out of this system.

Temperatures likely won’t drop below freezing across most of the region tonight. Image provided by WeatherBell.

So, how much do we expect now? Our thinking really hasn’t changed too much from yesterday. The jackpot is still going to be in the Worcester Hills and the Monadnocks, where 3-5″ is expected, possibly some heavier amounts. For the rest of us, a general 1-3″ from southern New Hampshire into the Merrimack Valley and Metro West, as well as the Seacoast of New Hampshire. The immediate Boston area will probably see around 1 inch. The biggest question mark for us is the area south of the Mass Pike into northern Connecticut, northern Rhode Island, and parts of southeastern Massachusetts. There will be some heavier precipitation here, but temperatures may also be a bit milder. Right now, we’re thinking 1-2″ for places like Woonsocket, Brockton, and Taunton, but it could end up a bit more if there is that heavier burst of snowfall. It also could end up less if temperatures stay in the upper 30s instead of dropping into the middle 30s.

The GFS model remains closest to our thinking for snowfall amounts. Image provided by Weathermodels.com

The rest of Saturday will feature rain showers and temperatures in the upper 30s to lower 40s, which will help melt away some of the snow from the morning. Skies will clear out at night, but clouds will come back in Sunday afternoon ahead of the next storm system. The good news is that Sunday will see temperatures well into the 50s and lower 60s, so that should take care of the rest of the snow. That next system? It’ll stay well offshore, but may produce a few rain showers on Monday. Is this the last time we’ll see snow until the fall/winter? Possibly. History says it can snow as late as mid-May here, so we can’t completely rule it out. In yesterday’s blog, we mentioned the possibility of flakes around April 28-29, based on the ECMWF Ensemble and its 51 members. Well, the newest run of that model no longer has that threat, but a significant portion of the ensemble members have at least a trace of snow for parts of the area around May 2, with a little bit of wet snow mixed in during a rainstorm. So, there’s a good chance tonight is our last accumulating snow for several months, but it might not be the last time we see some snowflakes. That same model also shows high temperatures near or above 70 on a regular basis starting around the middle of May.

Snow? Really?

After a winter where we didn’t really have much snow, it does look like there is some more coming, for at least part of the region.

Snowfall was well below normal across most of the region this winter. Image provided by the Northeast Regional Climate Center.

Some of you woke up to the ground being white this morning after a disturbance moved through with some snow and rain showers. Well, a similar occurrence is possible Saturday morning. A weak storm system will pass south of the region Friday night and Saturday. We’ll have some cold air (relative to mid-April) in place, with temperatures generally in the lower to middle 30s, especially north and west of Boston. As the system moves in, precipitation will develop late Friday night, and it will likely be in the form of snow north of the Massachusetts Turnpike. Light snow will fall through the early morning hours changing to rain across most of eastern Massachusetts, but possibly staying all snow from the Worcester Hills into the Monadnocks and maybe even southern New Hampshire before it ends during the afternoon.

A weak storm will bring in some light snow and rain Friday night and Saturday. Loop provided by Pivotal Weather.

It’s awfully tough to get accumulating snow in mid-April for a variety of reasons, but there are some things that will help this time. First of all, a lot of the snow will fall at night. Once the sun comes up, the sun angle is similar to late August, so it’s awfully tough to accumulate in the daytime. Second of all, temperatures will be close to freezing. Third, the snow may come down at a decent clip, which will help bring down a little bit of colder air from aloft. Working against accumulating snow is the fact that the ground is warm. There aren’t many sources for ground temperatures, and the nearest station is in Bennington County, Vermont, but even there, the latest reading shows a soil temperature of 37, which is 3 degrees above normal. On pavement, it will have an even tougher time accumulating, if it at all. Despite air temperatures in the 40s and lower 50s this afternoon, pavement temperatures are in the 60s and 70s, thanks to the sunshine. They’ll drop at night, but with air temperatures staying above freezing, the pavement temperatures will as well. Any snow that does accumulate should quickly melt Saturday afternoon and evening, as rain and milder temperatures eat away at it.

It’s also fairly rare to get accumulating snow in late April. The last time that Boston or Providence had 1″ or more in late April or May was on April 28, 1987! In Lowell, 1″ or more has been recorded after April 16 only 6 times in the past 92 years, and the last one was on May 18, 2002. This is why we never declare winter to be “over” in March or even early April. Having said that, we’re not convince this is the last time we’ll see any flakes this season either. Many members of the ECMWF Ensemble are signalling the potential for some flakes around April 28-29. Will it happen? We’ll see. For now, it’s something to keep in the back of our mind and pay attention to.

So, how much snow are we expecting? Not much. For those of you inside I-495, you’ll see some flakes, but there will be little to no accumulation. From the Merrimack Valley into Southern New Hampshire, a coating to an inch, mainly on grassy surfaces. As you get into the hills of Worcester County and the Monadnocks, some places could see 2-4 inches of accumulation.

The GFS model is probably closest to our thinking for snowfall. Image provided by Weathermodels.com

We’re aware that many models are forecasting more snow than this, and over a wider area. However, the models are just tools, and knowledge an experience are a big factor in our forecasts. We explained why it’s tough to get accumulating snow at this time of year, and many of the models don’t factor that in. This is why you should always follow a trusted source for your forecasts. There are plenty of “Facebook Forecasters” out there who will just regurgitate the models, and gleefully tell you that 2-4″ or more is expected. Sure, it’s possible, but in reality, it’s not likely.

Another storm will pass south and east of New England on Monday, likely too far offshore to have much of an impact on us, but we’ll keep an eye on it anways. After that, as we mentioned earlier, we’ll keeping an eye on the period around April 28-29. Hopefully that doesn’t pan out and winter is truly over. However, this is New England, so who knows. For now, stay safe, and watch the snow fall Saturday morning.

More Strong Winds and Rain for Monday

A rather strong storm system will wreak all sorts of havoc on a large swath of the nation through the weekend and into Monday.

Low pressure will move out of the Plains states today and into the Great Lakes later Sunday into early Monday. Loop provided by Tropical Tidbits.

Low pressure is moving into the Plains states today, producing some strong to severe thunderstorms from Texas into the Southern Plains. That’s just the start of what will be a busy few days. As the storm moves into the southern Plains tonight, showers and thunderstorms, some strong to severe, will spread from Texas into the Mississippi Valley. To the north, snow is expected across the Central Plains. Some locations could pick up 6-12 inches this weekend in a swath from Nebraska and South Dakota into parts of Iowa, southern Minnesota, and Wisconsin.

A severe weather outbreak is possible across a large portion of the South on Easter Sunday. Image provided by the Storm Prediction Center.

Easter Sunday is the day that will likely grab most of the headlines away from the pandemic for a day. As the system moves into the Ohio Valley, warm, moist air will be drawn northward from the Gulf of Mexico, and as this clashes with the cold air advancing southward behind the storm, the ingredients will be in place for a severe weather outbreak. Severe weather may be ongoing as Easter Sunday dawns across the Lower Mississippi Valley, but activity will spread eastward during the day across the Deep South and the Tennessee Valley. Some of the stronger storms may produce damaging winds, large hail, torrential downpours, and likely numerous tornadoes. The risk will continue well into the overnight hours, especially in Georgia, eastern Tennessee and western portions of the Carolinas.

The severe weather threat shifts to the East Coast on Monday. Image provided by the Storm Prediction Center.

By Monday, the system will move into Ontario, dragging a strong cold front across the Eastern United States. Warm, humid air will continue to flow northward ahead of this front, triggering more showers and thunderstorms during the morning and early afternoon from northern Florida into the Mid-Atlantic states. Some of these storms could produce hail, strong winds, heavy downpours, and some tornadoes, especially from the Carolinas to the Delmarva Peninsula.

Heavy snow is likely from Wisconsin in the Upper Peninsula of Michigan Sunday into early Tuesday. Image provided by Weathermodels.com

To the north, heavy snow will continue behind the storm from northern Wisconsin into the Upper Peninsula of Michigan and Ontario. Snowfall totals of 10-20 inches or more are likely. Winds gusting to 40-50 mph will create significant blowing and drifting of the snow, with blizzard conditions at times.

Precipitation has been below normal across much of the Northeast during the first 100 days of 2020. Image provided by the Northeast Regional Climate Center.

Here in the Northeast, the big story will be the wind. Rain will be a secondary concern, with rainfall totals of 1-2 inches possible across much of the region. Some embedded thunderstorms may produce heavier downpours, especially in western New England and eastern New York, but flooding isn’t much of a concern. Precipitation has been below normal across much of the area through a good chunk of the winter and early Spring, so we need all the rain we can get, though maybe not quite this much at once. There will be some ponding on the roadways, and some of the smaller streams may overflow, but widespread flooding shouldn’t be a problem. The wind, on the other hand, will be a major problem.

High Wind Watches are in effect for parts of the Northeast, and these will likely expand over the next 12-24 hours. Image provided by Pivotal Weather.

As the system gets cranked up in Ontario, strong southerly winds will develop across the region. These will bring milder air into the region. We won’t quite reach the 90s that will set records across Florida on Monday, but 50s and 60s are still a bit above normal for mid-April around here. Southerly winds will increase Monday morning, with sustained winds of 25-35 mph expected during the afternoon. Wind gusts of 60-70 mph or higher are expected as well. This will likely result in power outages as they take down trees that are starting to show their leaves, along with power lines. Winds should start to diminish during the evening as a cold front moves through, bringing an end to the rain and shifting the winds into the west.

Wind gusts of 60-70 mph or higher could be widespread Monday afternoon. Image provided by WeatherBell.

Conditions should improve on Tuesday as high pressure builds in with some sunshine developing, but it will still be breezy as the now-powerful storm moves into northern Quebec, where heavy snow will likely continue.