Winter or Spring? It depends on your definition, as March could be either. In terms of the forecast for the next few days, we’ll have both.
For most people, spring (a.k.a. astronomical spring), begins with the vernal equinox, which takes place this year on Sunday March 20 at 11:33AM. For others, meteorological or climatological spring began on March 1. No matter which definition you use, it will feel like winter into Friday. High pressure builds in tonight, with clearing and very cold conditions. Temperatures will likely drop into the single numbers in some of the cold spots Friday morning. Friday will also be rather chilly despite ample sunshine. The high slides off to the east on Saturday as low pressure heads toward the Great Lakes. It will send a warm front toward our area. The front will be accompanied by plenty of clouds, and although temperatures will turn milder with the high sliding offshore, the real mild air won’t be here yet.
Saturday night, that warm front moves through with a few showers possible, but temperatures will rise overnight. Could be there a little freezing rain or sleet over the interior right at the start? Sure it’s possible, but right now, it looks like temperatures might be a tad too warm by the time any precipitation arrives. This sets up a Sunday that will definitely feel like spring, as gusty southwest winds send temperatures to near or even over 60 degrees across the area, except for the South Coast, where the wind off the still-chilly water will act as a seabreeze. What’s the catch? We’ll still have plenty of clouds along with some showers as low pressure passes north and west of the region.
As the system moves by, it will try to drag a cold front across the area, but it doesn’t look like it will get all the way through. This has implications for Monday. Areas south of the front will stay quite mild Sunday night, while it will turn cooler north of the front. By Monday, another system quickly approaches from the southwest. This one looks a little more potent, but it will ride along that stalled out frontal boundary. Rain will redevelop in the afternoon, and it could be heavy in spots. North of the front, as colder air moves in, we could see a change to snow, especially Monday night into early Tuesday. We’ll look at this in much greater detail in our Weekly Outlook early Monday morning.
Thursday night: Clear and cold. Low 7-14.
Friday: Mostly sunny. High 28-35.
Friday night: Clear during the evening, some clouds start to filter in late at night. Low 13-20.
Saturday: Increasing and thickening clouds. High 36-43.
Saturday night: Mostly cloudy, chance for a few showers, possibly a little wintry mix well inland. Low 27-34 during the evening, temperatures rise overnight.
Sunday: Cloudy, windy, and mild with occasional showers. High 57-64, a little cooler along the South Coast.
Sunday night: Mostly cloudy. Low 40-47.
Monday: Cloudy with periods of rain or showers developing, possibly mixed with snow or sleet well inland by late in the day and at night. High 47-54, possibly cooler across southern New Hampshire and northern Massachusetts.
While today is turning out to be a fantastic day across the region, significant changes are coming, and it won’t take long for them to happen.
A cold front is crossing the region this afternoon, which will bring an end to our record warmth. A few spots even managed to reach 70 today, but you can kiss the mild weather goodbye, as it won’t be back for a while. Temperatures quickly drop this evening and tonight as high pressure builds in, but clouds will start to stream back in on Thursday as low pressure heads toward the Ohio Valley. The system will then redevelop off the Mid-Atlantic coastline, and pass south of New England on Friday. As you’d expect with a system passing south of us in late February, this will produce snow for most of the area. The exact track of the system will determine how much snow we get (more on that in a bit).
We’ll see snow develop before daybreak on Friday, and it may fall heavy at times during the morning and afternoon. At the same time, warmer air will be trying to move in aloft, which would allow the snow to change to sleet and/or freezing rain from south to north during the late morning and early afternoon. At this point, the only places that are likely to get above freezing and change to plain rain will be along the South Coast and across the Cape and the Islands. The question now is, how far north does that change to sleet occur, since it will have a significant impact on the accumulation totals? Most of the models only bring the change as far north as the Mass Pike. However, there is at least one model that brings the changeover all the way northward into southern New Hampshire. This concerns us a little, and we’re going to hedge our bets against this in the snowfall forecast, as you’ll see below.
No matter how far north the changeover gets, as the system starts to pull away later on Friday, everything should change back to snow before winding down and ending in the evening. While this will likely impact the evening commute, the impact will be considerably less than what the morning commute experiences.
As for amounts, this is where things get tricky, since any mixing will cut down amounts significantly. There has been a trend in the models over the past 12 hours or so to shift the axis of heaviest snow into northern and central Massachusetts, with a bit less as you head into southern New Hampshire. Having said that, here’s our thinking as of now:
Cape Cod: 2-4″ South Coast: 3-6″ Southeastern MA/RI: 5-9″ Metro Boston/MetroWest/Merrimack Valley/North Shore: 6-12″ Central and Southern New Hampshire/NH Seacoast: 5-10″
The ranges are a bit wider than we normally like, but this reflects the uncertainty. The less sleet that mixes in, the more likely you are to be near the higher end of the range. Conversely, the more sleet that mixes in, the more likely you are to be toward the lower end of the range. We’ll update this forecast in our Weekend Outlook tomorrow afternoon.
We’ve got quite the week coming up with everything from some snow and bitterly cold temperatures to heavy rain and possibly more record highs by the end of the week.
Snow showers will come to an end this morning, then skies will start to clear out this afternoon as high pressure starts to build in. Despite the developing sunshine, temperatures will only be in the 20s, which is 10-15 degrees below normal for mid-February. As skies become clear tonight and winds diminish, combined with the fresh snowcover, we’ll have some radiational cooling. Temperatures will likely drop into the single numbers, with some sub-zero readings possible. Tuesday remains chilly, but not quite as cold as today as the high pressure area continues to build in. By Wednesday, that high shifts offshore, and a significant temperature moderation develops. The milder air will be accompanied by clouds though as a storm system begins to move toward the region.
By Thursday, that system draws nearer, with gusty southwest winds sending temperatures well into the 50s and possibly 60s, with more record highs possible. While temperatures will be mild during the day, it looks like the warmest temperatures will be at night. We could be near or above 60 degrees at midnight Thursday night across the region. We’ll also have some heavy rain as the system gets closer, which combined with the mild weather, will help melt much of the snow that remains on the ground. A widespread soaking rainfall is likely, with rainfall totals of more than an inch possible. We wouldn’t even be surprised if there’s a rumble of thunder. This storm will likely produce some severe weather across the South, and while that’s not likely here, a few thunderstorms are possible. Friday likely starts off warm and wet with temperatures still in the 50s at daybreak, but as a strong cold front comes through during the morning, the rain will end, and temperatures will drop during the day. High pressure builds back in for the weekend with dry and seasonably cool conditions for Saturday, but we may start to turn milder again on Sunday.
Monday: Snow showers ending in the morning, skies start to clear out by late in the day, breezy. High 18-25.
Monday night: Becoming mostly clear. Low -2 to +5.
Tuesday: Sunshine and some afternoon clouds. High 23-30.
Tuesday night: Clear to partly cloudy. Low 6-13.
Wednesday: Sunny in the morning, clouds start to stream in during the afternoon, becoming breezy and milder. High 38-45.
Thursday: Plenty of clouds with some sunny breaks, especially in the morning, showers developing in the afternoon, becoming windy. Wind-swept rain likely at night, possibly some thunder as well. High 56-63. The warmest temperatures are likely at night.
Friday: Windy with rain ending in the morning, clearing during the afternoon. High 47-54 at daybreak, temperatures drop during the day.
Hope you enjoyed the record warmth today, because Mother Nature is going to quickly remind you that it is still February.
Unseasonably mild temperatures continued across the region on Saturday, with a few records set, but a cold front moved through around midday, and a stronger one will move through this evening, bringing an abrupt end to the mild weather. Temperatures will quickly drop tonight as the front pushes offshore, and on Sunday, most places will likely be in the 30s or even upper 20s during the daytime. That’s not the big story though.
A wave of low pressure will ride along the front on Sunday, passing south and east of the region. It will be close enough to produce some light snow and snow showers across parts of eastern Massachusetts and Rhode Island, possibly even into southern New Hampshire, during Sunday morning and early afternoon. Most of the snow will remain light, with accumulations of an inch or two possible, mainly from Boston southward. The story doesn’t end there. As the low passes by, winds will shift into the northeast, which will result in some ocean-effect snow across parts of Cape Cod and coastal Plymouth County, and possibly Cape Ann as well. The areas that receive snow will be highly dependent on the wind direction. Northeast winds will spread the snow inland across southeastern Massachusetts, but as winds shift into the north Sunday night, the bands of ocean-effect snow will retreat closer to the coast of Plymouth County and across Cape Cod. By Monday morning, winds will shift into the northwest, bringing an end to the snow for most of us.
How much snow may fall? North and West of I-495, just a dusting to perhaps a half an inch. From 495 to I-95, some spots could see an inch, possibly 2 inches. It’s areas south of Boston (and Cape Ann), that may need shovels (and possibly plows). Across interior portions of southeastern Massachusetts as well as Cape Ann, we could see 2-4 inches of snow. The “jackpot” is likely to be across coastal Plymouth County as well as parts of Cape Cod, where as much as 4-7 inches could accumulate.
High pressure builds in behind this system on Monday with much colder weather. Despite sunshine developing in the afternoon, temperatures will only rise into the lower to middle 20s for highs, with single numbers and lower teens likely Monday night as skies clear out and winds die down. Tuesday also looks chilly, though likely a few degrees milder, but a big warmup is likely for the middle to latter half of the week. In fact, we could make a run at 60 again on Thursday, before another system brings in some rain.
There are some indications that this arctic blast for Monday and Tuesday could be the last really cold blast of the winter. Oh, it’ll still be cold, it’s only mid-February after all, but days with highs in the 20s and lows in the single numbers or below zero may be done for the year, though this is far from a guarantee. We’ve been known to have arctic blasts into March and even early April, though with the increasing sun angle, they tend to lose their staying power. This does not mean that winter is over, not by a longshot. We still can get snow around here well into April and even May if things set up properly. The longer range models are indicating that a milder pattern should start to take hold soon, and last into March. However, these same models also still show the threat for snow well into March, so don’t go putting away the winter gear just yet.
We’ve got a lot going on over the next few days across the region, and you probably won’t like most of it.
A storm system will develop off the Mid-Atlantic coast tonight, and rapidly strengthen as it heads northeastward, passing well south and east of the region on Friday. However, it will be close enough to spread some rain and strong winds into Cape Cod and possibly southeastern Massachusetts. At the same time, a cold front will drop down from the northwest, ushering arctic air back into the region. This may allow the rain to change to snow before it ends. Temperatures will quickly drop Friday afternoon and evening as gusty northwest to north winds continue to send the arctic air in. Any surfaces that are wet from the rain across southeastern Massachusetts will quickly freeze up Friday afternoon and evening, so keep this in mind if you’re heading out that evening.
We’ll drop into the single numbers by Saturday morning, with some subzero lows north and west of Boston. With strong winds, wind chills will be well below zero Friday night and Saturday morning, so dress appropriately if you’ll be outside. Saturday looks to be a day similar to this past Tuesday with sunshine and some afternoon clouds, possibly a few snow showers across Cape Cod, and temperatures struggling to reach the lower to middle teens. Winds die down Saturday night, resulting in another chilly night, with subzero lows possible once again. Sunday starts off with some sunshine, but clouds start to move in during the afternoon as temperatures start to moderate. This brings us to the complicated part of the forecast.
Another strong low pressure system will develop across the Southeast and make its way up the East Coast on Sunday. There is still some uncertainty with the exact track that the storm will take, but for now it looks like it may stay near the coast or just inland, passing directly over, or just west, of our area on Monday, though this is subject to change. This track would result in snow changing to sleet and/or freezing rain and then plain rain across much of the area. However, this is far from a guarantee. There are still some models that bring the storm a little farther south and east, which would result in more snow and less rain, but as we’ve mentioned numerous times, the models have been less than trustworthy beyond 2 or 3 days recently. When (or if) a change to mix and/or rain occurs will also have a significant impact on how much snow accumulates. Given the amount of uncertainty, it’s still WAY too early to try and pin down any potential accumulations, but it’s safe to say that the farther north and west of Boston you are, the better the chance you’ll need to fire up the snowblower or find your shovels. We’ll try to post an update this weekend, once we have some better clarity on the storm.
Thursday night: Partly to mostly cloudy, rain may develop across Cape Cod towards daybreak. Low 26-33.
Friday: Mostly cloudy, rain likely across Cape Cod and southeastern Massachusetts, possibly changing to snow before ending, becoming windy. High 35-42, but temperatures will start to quickly drop in the afternoon.
Friday night: Clearing, windy, and much colder, except partly cloudy with a few snow showers across Cape Cod. Low -3 to +4, except milder across Cape Cod and the Islands.
Saturday: Partly to mostly sunny, breezy, and very cold, except partly sunny with a few snow showers across Cape Cod. High 10-17.
Saturday night: Clear skies with diminishing winds. Low -2 to +5, except milder across Cape Cod and the Islands.
Sunday: Sunshine to start the day, clouds move in during the afternoon. High 23-30.
Sunday night: Cloudy and becoming breezy with snow developing, possibly rain across Cape Cod. Low 14-21.
Monday: Snow, possibly changing to sleet/freezing rain/rain, especially the farther south and east you go. High 39-46.
Dig out the thermals and heavy winter gear, some really cold air is on the way.
Temperatures will turn colder today despite some sunshine, but this is just the opening act for what is on the way. An arctic cold front will cross the region this evening. It may produce some snow showers or squalls, so if you’ll be out this evening, be prepared for a short burst of snow that could significantly reduce visibility and drop a quick coating on the roads. Once the front moves offshore, bitterly cold air will flood into the region for Tuesday and Tuesday night. Temperatures will drop below zero in parts of the region Tuesday morning. Despite plenty of sunshine Tuesday afternoon, highs may struggle to reach the lower teens across most of the area, with wind chills that are below zero. Across Cape Cod, there may not be as much sunshine, as northwest winds blowing over the relatively mild water of Cape Cod Bay could produce some ocean-effect snow showers, especially across the Outer Cape. We’ll have another bitterly cold night Tuesday night, with subzero lows possible once again, but as high pressure slides off to the east on Wednesday, temperatures should start to moderate. It’ll still be chilly, but highs should get into the 30s across the area.
Temperatures will turn colder again for the end of the week, but there are bigger concerns. We’ve cautioned you recently that the models have performed rather poorly beyond 2 or 3 days, and that is still the case, so this part of the forecast is highly uncertain. However, many models are showing the potential for a powerful ocean storm to develop late Thursday into Friday, and a second storm to do the same over the weekend. The fact that they all show this gives us a little more confidence that they both may actually develop. The problem is, that’s about all they agree on. They don’t agree on the timing of the storms, the track they might take, how strong they’ll get, and what, if any, impacts they may have up here. These are things that we’ll be keeping a close eye on as the week goes by, but for now, what you read below is our “best guess” (for lack of a better term), but it is very low confidence.
Monday: Partly sunny. High 23-30.
Monday night: Partly cloudy and breezy, some snow showers or squalls are possible during the evening. Low -2 to 5 north and west of Boston, 6-13 south of Boston, wind chills could drop to -10 to -20 by daybreak.
Tuesday: Mostly sunny and very cold, except partly to mostly cloudy with some snow showers across parts of Cape Cod. High 8-15, with wind chills below zero.
Tuesday night: Partly cloudy. Low -2 to +5.
Wednesday: A mix of sun and clouds, breezy, and milder. High 31-38.
Thursday: Partly to mostly cloudy. High 35-42.
Friday: Mostly cloudy and breezy, chance for some light snow or snow showers, mainly across southeastern Massachusetts and Cape Cod. High 28-35.
Saturday: Partly to mostly sunny and cold. High 21-28.
Sunday: Plenty of clouds with a chance of snow, especially in eastern Massachusetts. High 28-35.
Our first snowstorm of the season is on the way for Friday, but it’s just part of a colder pattern we’re heading into for the weekend and beyond.
Low pressure is moving across the Tennessee Valley this afternoon, and it will head east-northeastward, moving off the Mid-Atlantic coast tonight, passing south and east of New England on Friday as it intensifies. We’ll see snow developing before daybreak, and it may fall heavy at times during the morning, which will result in significant problems for the morning commute. The snow should come to an end by mid-afternoon across the region. Based on the trends in the models since last night, we are adjusting our snowfall forecast upwards a bit, but not that much. Here’s our latest projections:
The storm pulls away Friday evening, and skies clear out as high pressure builds in, setting up a sunny but rather chilly Saturday, with many places likely staying in the 20s all day. With clear skies and fresh snowcover, temperatures will quickly plunge Saturday evening into the teens and possibly single numbers in some spots. Clouds stream back in late Saturday night as another system moves toward the region. While this system looks a bit milder, with southerly winds warming things up a bit on Sunday, the models have been trending less mild with every run. With that in mind, we’ll probably see some snow showers or a little freezing rain develop north and west of Boston Sunday afternoon, changing to rain by evening. Keep this in mind if you are going to be out and about Sunday afternoon. Elsewhere, just plain rain is expected. The rain may mix with some wet snow before winding down around daybreak Monday. After that, some of the coldest air thus far this winter will pour into the region. Temperatures may not rise much, if at all, Monday afternoon. The coldest weather looks to arrive on Tuesday, when highs may stay in the teens, with subzero lows possible Tuesday night. We’ll have more info on that in our Weekly Outlook early Monday morning.
The first weekend of meteorological summer is upon us, and it’ll certainly feel like summer around here.
A warm front will move across the region this afternoon, and as an upper-level disturbance swings through tonight, those two will combine to bring in some showers and thunderstorms. While a few of them may produce some heavy rain near the South Coast, most of us shouldn’t see that much rain tonight. Another upper-level disturbance crosses the region on Friday accompanying a dying cold front. This will produce another round of showers and thunderstorms, mainly during the afternoon and evening. A few of these storms could produce downpours and gusty winds.
Once everything moves offshore Friday night, high pressure builds back in for the weekend and Monday. We’ll dry out on Saturday and with developing sunshine, temperatures should get well into the 80s away from the South Coast. For Sunday and Monday (and into the middle of next week), we’ll have a Bermuda High in place, which means southwest winds pumping very warm to hot and humid air into the region. Temperatures will be near or just above 90 for most of us on Sunday, and on Monday, highs will reach the lower to middle 90s, perhaps even some upper 90s, which will be close to the record highs for much of the region. While it won’t be as humid as it normally is deeper into the summer, it’ll be fairly humid by early-June standards, with dewpoints in the 60s, meaning that it will feel like mid to upper 90s during the afternoon.
Thursday night: Cloudy with a few showers or a rumble of thunder, mainly along the South Coast. Low 59-66.
Friday: Plenty of clouds with some showers and thunderstorms possible, mainly during the afternoon. High 74-81, a little cooler along the South Coast. Offshore: Southwest winds 15-20 knots, gusts to 30 knots, seas 3-6 feet, visibility 1-3 miles in showers and fog UV Index: Moderate. Water temperatures are in the upper 50s to near 60.
Friday night: Showers and storms taper off during the evening, some clearing possible late at night. Low 56-63.
Saturday: Becoming partly to mostly sunny. High 83-90, cooler along the South Coast. Offshore: Southwest winds 15-25 knots, gusts to 30 knots, seas 3-5 feet, visibility 1-3 miles in morning fog. UV Index: High.
Saturday night: Partly cloudy. Low 64-71.
Sunday: Sunshine and a few clouds, becoming humid. High 88-95, cooler along the South Coast. Offshore: Southwest winds 10-15 knots, gusts to 25 knots, seas 2-4 feet, visibility 10 miles or better. UV Index: Very High.
Sunday night: Clear skies. Low 64-71.
Monday: Partly to mostly sunny. High 90-97, cooler along the South Coast. Offshore: West to southwest winds 10-15 knots, gusts to 25 knots, seas 2-4 feet, visibility 10 miles or better. UV Index: Very High.
Bond villian Elliot Carver said it in “Tomorrow Never Dies”, but it’s appropriate for the forecast for the next several days – “Let the mayhem begin”
We start off with a developing low pressure system well offshore tonight. The system will continue to strengthen, but also continue to pull away, so it won’t directly impact us. However, it will produce northerly winds around here that will serve two purposes. First, they’ll continue to produce some ocean-effect snow across parts of eastern Massachusetts and the New Hampshire Seacoast, and second, they’ll usher in some of the coldest air thus far this winter.
First, we’ll look at the ocean-effect snow. It’s been ongoing since early this morning, and will continue off and on into this evening. While it won’t amount to much for a good chunk of the region, right along the coast, especially Cape Ann, coastal Plymouth County, and Cape Cod, could see an inch or two in spots. On Friday, a disturbance rotating around the ocean storm will bring some more ocean-effect snowfall back into Cape Cod. This could result in additional accumulations, especially across the Outer Cape, where a few inches is possible.
Back to the cold air. This past week has been rather chilly compared to the rest of January, but temperatures have only been near to a little below normal. That’s going to change tonight and this weekend. Skies will start to clear out tonight (except for Cape Cod), and it’s going to get cold. Temperatures will likely drop into the single numbers for much of the region tonight, but it will remain quite breezy, so we’re looking at wind chills of 10 to 20 below zero Friday morning. Wind Chill Advisories have been posted from Worcester County westward, but even without the advisory, you should know enough to dress warmly if you have to go outside.
Friday looks rather chilly as well. Some clouds may move in from the ocean, but even in places where the sun is out, it’ll still be breezy and cold, with daytime highs only in the teens to lower 20s. Skies clear out again Friday night and winds will start to diminish, so we’re looking at another cold night, with some places possibly dropping below zero. Saturday should feature a lot of sunshine, but it will still be cold, with highs only in the upper teens to lower 20s. After another bitterly cold night Saturday night, temperatures should start to moderate a bit on Sunday, but we’ll also see clouds starting to move back in ahead of another storm system heading this way. This brings us to Monday.
For several days now, most of the forecast models have been showing the potential for a storm system to impact the Northeast early next week. They’ve bounced around with the details on strength, timing, and track, but in general, there’s been a fairly strong signal that something is going to happen around here after we flip the calendar to February. Well, that signal hasn’t gone away, and the Universal Hub website has upgraded to a Level 2 on the French Toast Alert System. In other words, don’t worry just yet. However, knowing how the media can be around here, and knowing what the models are showing, we’re issuing our own Extreme Hype Watch. An Extreme Hype Watch is issued when conditions are favorable for media hype of an event to reach extreme levels within the next 48-72 hours. If conditions warrant, a Hype Advisory or Extreme Hype Warning will be issued as the event draws nearer.
As for the system itself, there are still plenty of questions that need to be answered. We’ll have a large high pressure area in eastern Canada keeping some cold air in place. It’s not quite in the ideal position for a big storm here, but it is there. We’ll have a low pressure system moving through the Midwest that will redevelop over the Mid-Atlantic states, then head northeastward, likely passing south and east of New England, close to the “benchmark”. The benchmark is at 40 degrees North latitude and 70 degrees West longitude, about 90 miles south of Nantucket. Storms that pass over that spot are usually (but not always) in a prime position to deliver heavy snow to much of the region. Storms that pass north and west of there usually end up with a rain/snow line farther inland, and storms that pass south and east of there don’t always deliver snow far inland. This is more of a general rule than an absolute, but it’s something we look for. The other issue we have is that an upper-level low pressure area will be moving in, and the storm may get stuck underneath it, which could stall it out or have it meander around south of us for a day or so, which would result in an extended period of precipitation.
In addition to the models, another tool we use is analogs. You will most often hear about these in relation to a seasonal pattern or a hurricane season, but we can also use them for individual storms. Basically, we compare the pattern to previous setups, and see how it compares, and see what those previous setups produced to give us an idea of what is possible. Now, these analogs are run compared to the forecast of one model, so if that model isn’t the one your using, then the analogs might not be of much help. Based on the midday run of that model, the best analog for the pattern early next week is the storm of January 26-28, 2015. You may recall that storm received an extreme amount of media hype, and did produce very heavy snow around here, but was considered a “bust” in New York City, where the actual amounts fell well short of the forecast. It also was the storm that essentially kick-started our 6-week snow blitz (and also was responsible for the formation of the original StormHQ Facebook page). Using the Top 15 analogs for the forecast pattern, here’s the average of snowfall from those 15 systems:
As you can see, there is a signal for a significant snowstorm, which is why we’re going to be monitoring this closely for the next several days. We’re not going to post any model snow forecasts yet because there’s still too much uncertainty. We’ll let the media and Facebook Forecasters take care of that. If conditions warrant, we’ll issue another blog post either Saturday or Sunday as the details become more clear.
Thursday night: Mostly cloudy along the coast with a few snow showers across the Cape, clearing inland, breezy. Low 1-8.
Friday: Intervals of clouds and sun, more snow showers across Cape Cod, windy. High 13-20.
Friday night: Lingering clouds across Cape Cod, clear elsewhere, still breezy during the evening. Low 2-9.
Saturday: Plenty of sunshine, except for some clouds across the Outer Cape. High 16-23.
Saturday night: Clear skies. Low 0-7.
Sunday: High clouds stream in. High 22-29.
Sunday night: Thickening clouds. Low 12-19.
Monday: Cloudy and breezy with a chance of snow (or possibly rain south of Boston) High 30-37.
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.
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.
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.
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.
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.
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.