The Party’s Over – Here Comes the Snow

We haven’t had a decent-sized snowstorm around here since late November. Well, that is about to end, much to the dismay of most of you. We’ve got several different concerns with this system, so we’ll try and touch on all of them.

Winter Storm Watches and Warnings are in effect for most of the Northeast with a Coastal Flood Watch for parts of the Massachusetts coastline. Image provided by Pivotal Weather.

We’ll start with what’s going on now. High pressure is building into Quebec, and this will bring cold air into the region. Tonight will be chilly, with lows in the teens, maybe even some single numbers. Meanwhile, low pressure is moving out of the Southern Plains. This low will move towards the Appalachians on Saturday, then off the Mid-Atlantic coastline Saturday night. This brings us to forecast problem number 1. Where does the low track from there? This is a critical point, as it will help determine what type of precipitation falls across the area. Some models keep the storm offshore, south of the Cape and Islands, while others bring it right across southeastern New England. We’re thinking it tracks pretty close to the Islands, but stays just to the south. By Sunday, it moves into the Gulf of Maine, and takes all of the precipitation away.

As for the timing of that precipitation, there’s not much disagreement among the models. Snow should move in during the evening hours (7-9pm) from west to east, and end during the afternoon (3-5pm) on Sunday, except across Cape Cod and parts of southeastern Massachusetts, where it may linger into Sunday night. The heaviest precipitation will likely fall between about 11pm Saturday and 8am Sunday, so if you don’t have to be out then, we’d recommend that you stay where you are.

The High-Resolution NAM model shows the progression of the precipitation across the region. Blue is snow, orange is sleet, purple is freezing rain, and green/yellow is rain. Loop provided by Weathermodels.com

What type of precipitation is going to fall? Well, that is a BIG question, that is still in doubt for a large portion of the region. It should start as snow for everyone. It will likely change to rain across Cape Cod and the South Coast, and parts of southeastern Massachusetts. In between? That’s where things get really complicated. As we usually see during storms, we’re going to have a “coastal front” set up. Basically, the milder air from the ocean will push inland a bit. If you are south and east of this coastal front, temperatures will be near or just above freezing. If you are on the other side of the front, temperatures will be in the teens. Eventually, this front will collapse to the coast on Sunday, bringing the cold air in everywhere (more on that later). But the surface is only part of the equation. Warmer air will also move in aloft. How far inland it moves is something that that models disagree on right now. With warm air aloft and cold air at the surface, the precipitation will change to sleet or freezing rain, depending on how thick the layer of warm air is above the surface. Obviously, this will have a significant impact on snowfall amounts. Everything should go back to all snow Sunday afternoon as the coastal front collapses toward the coastline.

The high-resolution NAM model shows a well-defined coastal front setting up in the Merrimack Valley and the I-495 belt Sunday morning. Image provided by WeatherBell.

We’ve got more concerns than just what falls from the sky though. The full moon is Sunday night, which means that tides will be astronomically high. That is usually enough for some minor coastal flooding in a few spots. However, when you add in east to northeast winds of 15-25 mph and gusts to 40-50 mph (or more), then you get coastal flooding in a much wider area, possibly even some moderate flooding in the more vulnerable locations. This is mainly a concern for the high tide that occurs Sunday morning. The winds will also be a concern inland, as it will create blowing and drifting snow, making driving even more hazardous.

We mentioned earlier that the coastal front would collapse to the coastline during the afternoon, bringing cold air back in everywhere. As that cold air comes rushing in, we expect everything to quickly freeze up Sunday afternoon and evening. This will create black ice on the roads, but more importantly, any snow still on your driveway, cars, roads, etc, will quickly turn into cement. You’ll want to get outside and quickly clear everything off, because the longer you wait, the more difficult it will become. Temperatures will continue to drop Sunday night, and as high pressure builds in, skies will clear out, which may allow for viewing of the total lunar eclipse Sunday night. On Monday, temperatures won’t rise that much, with many places likely staying in the single numbers or lower teens. It will still be breezy, so wind chills may stay below zero all day long. Temperatures will start to moderate on Tuesday, but longer-range indications are that we are in a colder (and stormier) pattern now, so winter has finally arrived.

This is the forecast high temperatures for Monday based on the GFS model. It’s going to be cold. Image provided by Weathermodels.com

OK, finally, the part you’ve all been wondering – how much are we getting? As we’ve said, the amount of sleet and freezing rain will have a significant impact on snow accumulations, so we’re going to keep our ranges somewhat wide for now, and if need be, we’ll put out an update on Saturday.

Cape Cod: 2-4″
Southeastern Massachusetts/Southern Rhode Island: 3-6″
I-95 corridor (including Boston and Providence): 4-8″
MetroWest/North Shore: 6-12″
Merrimack Valley/NH Seacoast: 8-14″
Southern NH/Southern ME (Nashua/Manchester/Portland): 10-16″
Central NH (Concord): 12-18″

The NAM model is probably closest to our thinking right now, though some of these numbers may be a bit higher than our thoughts. Image provided by the College of DuPage.

If time allows, and/or there is a significant change in the forecast, we’ll update this on Saturday.

Weekly Outlook: December 31, 2018-January 6, 2019

Remember last week when we hinted that First Night could be really cold? Well, it seems as though we were wr….wro….wro….we were a little off.

It is NOT going to be a fun First Night in the Dakotas. Image provided by Weathermodels.com

First Night is actually going to be bitterly cold, if you’re planning on spending it in Fargo, where wind chills will be 25 to 35 degrees below zero when the clock strikes midnight. Around here? It’ll be a tad milder. Low pressure will move from the Great Lakes into northern New England later today and tonight. Precipitation will move in this evening, and it will likely still be cold enough for some snow, sleet, or freezing rain from the Merrimack Valley northward, at least at the start. Elsewhere, just some rain is expected. Milder air will move in aloft, and eventually at the surface too, changing the precipitation to rain everywhere overnight. That warm air may take its time moving in, especially from the Merrimack Valley into southern New Hampshire, but New Years Morning will likely be quite mild across much of the area. Don’t get used to it, as a cold front moves through during the morning, with windy and colder conditions likely for the afternoon.

The NAM model shows cold air stubbornly hanging around in southern NH and the Merrimack Valley Tuesday morning, while everywhere else turns milder. Image provided by WeatherBell.

Tuesday afternoon is also when the Winter Classic takes places, featuring two of the absolute best sweaters in the NHL (and two of our favorite teams here at StormHQ) – the Boston Bruins and the Chicago Blackhawks. We’ll refrain from comment about the fact that it’s taking place at the home of the Angry Leprechauns – Notre Lame, er, Dame, or that outdoor hockey games are much better on TV than in person (trust us, we’ve experienced it), but for the game itself, it should be cloudy with temperatures in the middle 30s, which is pretty much perfect for outdoor hockey.

We’re not fans of outdoor hockey games, but we are fans of the Bruins and the Blackhawks. The weather will cooperate, so let’s hope for a great game (and a Bruins victory). Image provided by the National Hockey League.

As we head deeper into 2019, things get quieter (and colder) around here for a few days. High pressure builds in, and we’ll have generally dry and cool conditions for much of the remainder of the week, as we remain in a split jet-stream pattern. Basically, we’ve got a northern stream keeping some storms across southern Canada and to our north, and a southern stream keeping the warmer, juicier storms to our south. This will be the case on Friday when it looks like a southern stream storm will come along and give us some rain, while the northern stream remains locked up in Canada. If you don’t like snowstorms, then you want this pattern to continue. Why? Because if the streams cross, to quote Dr. Egon Spengler, “It would be bad.” That’s usually how we end up with some of our bigger snowstorms in the winter. As the storm moves by, colder air will work in behind it, with the rain possibly changing over to snow before ending on Saturday. High pressure then returns for next Sunday.

New Years Eve: Becoming mostly cloudy. High 37-44.

Monday Night: Cloudy and becoming breezy with rain developing, starting as some snow or a wintry mix from the Merrimack Valley into southern New Hampshire. Rain ends towards daybreak. Low 32-39 during the evening, then temperatures will hold steady or slowly rise overnight.

New Years Day: A lingering shower early, then becoming partly to mostly sunny, windy, and colder. High 49-56 in the morning then temperatures quickly drop through the 40s during the afternoon.

Tuesday night: Clear to partly cloudy. Low 18-25.

Wednesday: Mostly sunny. High 27-34.

Thursday: Partly sunny, slight chance for a snow or rain shower. High 35-42.

Friday: Cloudy with rain developing in the afternoon, continuing at night. High 38-45.

Saturday: Cloudy and breezy with rain, possibly mixing with or changing to snow before ending late in the day. High 34-41.

Sunday: A mix of sun and clouds, breezy. High 36-43.

Hurricanes, Severe Weather, and Snow, All at the Same Time (not the Same Place)

For the third year in a row, the “M” storm in the Atlantic is prepared to wreak havoc on a populated area, but Michael isn’t the only headline maker in the weather at the moment.

Hurricane Michael isn’t the only storm in the news, but it is the biggest threat at the moment. As of early Tuesday afternoon, Michael was centered about 335 miles south of Panama City, Florida, moving toward the north at 12 mph. Maximum sustained winds are near 110 mph, making Michael a Category 2 Hurricane. Additional strengthening is expected over the next 12-18 hours as the storm moves over the warm waters of the eastern Gulf of Mexico. Hurricane and Storm Surge Warnings are in effect for the Florida Panhandle and the Big Bend area of Florida, with Tropical Storm Warnings and Watches surrounding the Hurricane Warnings. Tropical Storm Watches are also in effect for the Atlantic coast from northeastern Florida into South Carolina.

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Michael is going to pack quite a wallop when it slams into the Florida Panhandle Wednesday afternoon. Image provided by the National Hurricane Center.

Michael is expected to make landfall in the Florida Panhandle Wednesday afternoon, likely as a Category 3 storm. Strong winds, torrential rainfall, storm surge, and some tornadoes are all possible with this storm. Unlike Florence, which hung around the Carolinas for days and dumped incredible amounts of rainfall on the region, Michael is expected to keep moving at a steady pace, emerging off the Mid-Atlantic coast by Friday morning. Rainfall totals of 5-10 inches are still expected in parts of the region, which will produce flooding in some areas, especially in Carolinas, where many areas are still recovering from Florence. Right along the coast, a storm surge of 6-12 feet is possible, especially in the Big Bend area of Florida. Fortunately, this area is not heavily populated, but for the residents that do live in this area, storm surge flooding is a significant threat.

Once it moves back into the Atlantic early Friday, it should pass well south of our area. The northern edge of the rainfall from the system could reach the South Coast, but the bulk of the heavy rain should remain well to the south.

This is the 3rd year in a row that the “M” storm is expected to result in significant damage to a populated area. In 2014, Category 5 Hurricane Matthew left a path of death and destruction across parts of Haiti, Cuba, the Bahamas, and eventually parts of the southeastern United States. Last year, Category 5 Hurricane Maria devastated the northeastern Caribbean, including Puerto Rico and the US Virgin Islands. While Michael is not expected to become a Category 5 storm, it is still expected to result in significant damage to parts of Florida and the Southeast.

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Tropical Storm Leslie has been around for near 2 weeks and still looks rather healthy. Loop provided by NOAA.

Meanwhile, in the eastern Atlantic, Tropical Storm Leslie refuses to go away. As of midday Tuesday, Leslie was centered a little more than 1000 miles west-southwest of the Azores, moving toward the south-southeast at 13 mph. Maximum sustained winds are near 65 mph. The forecast for Leslie calls for a turn more toward the east over the next few days while it strengthens back into a hurricane. Leslie is expected to remain over open waters for the next few days, and could become an extratropical storm this weekend while continuing on a general easterly track.

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Nadine is a fish storm. Nothing to worry about here. Image provided by Tropical Tidbits.

To the south, Tropical Storm Nadine as formed nearly 500 miles southwest of the Cabo Verde Islands. Nadine has maximum sustained winds near 40 mph, and is moving toward the west-northwest at 9 mph. Nadine is expected to remain fairly weak over open waters for the next several days while turning more toward the northwest. As it moves over colder water late this week and this weekend, it should weaken and eventually dissipate.

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What month is it again? 70s and 80s early in the afternoon on October 9th? Image provided by WeatherBell.

Back in the United States, unseasonably warm conditions remain in place across much of the eastern half of the nation. Temperatures are in the 70s and 80s across much of the region, which is 15 to 25 degrees above normal. A strong frontal system is located in the Plains states this afternoon, separating the warm air in the East, from much cooler weather behind it in the Plains and the Rockies. Right along this front, which hasn’t moved much for the past 24 hours, severe weather and heavy rainfall are common this afternoon.

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That’s snow in Colorado, and heavy rain along with severe weather from Texas into the Central Plains this afternoon. Loop provided by WeatherTAP.

Several tornadoes have been reported already today, including a few in the Oklahoma City area, and more are expected later today and tonight. Heavy rainfall is also expected from Texas into the Central Plains and parts of the Upper Midwest. Rainfall totals of 1-3 inches and locally heavier may produce flash flooding in some areas. Flash flood watches are in effect for much of the region.

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Several inches of snow is expected form the Plains into the Upper Midwest over the next few days. Image provided by Pivotal Weather.

On the other side of the front, where much cooler weather is in place, rain is expected to change over to snow as low pressure rides along the front and into the Midwest. Winter weather advisories have already been posted for parts of the region. Snow is already falling in parts of Colorado this afternoon, and several inches may fall over the next 36-48 hours from western portions of Kansas and Nebraska into the Dakotas and northern Minnesota.

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Some heavy rain is possible across our area on Thursday as a strong cold front approaches the region. Image provided by WeatherBell.

As the system moves eastward, it will spread some heavy rain and thunderstorms into our area on Thursday. We’re not expecting any severe weather, but some heavy downpours are possible, especially from western Massachusetts into southern New Hampshire. Some localized flooding may result. Once this front pushes offshore, much cooler weather will settle in for the Friday and the weekend.

Wet Weather and High Humidity Are Coming

You know that dry weather we’ve had for much of the Spring and Summer? How about those warm days with low humidity? Well, both will be a distant memory by this time next week.

A weather pattern that is both typical and atypical of summer at the same time is going to settle into the nation over the next several days. The typical part is that we’ll have a ridge of high pressure off the East Coast, and another one in the Southwest. The ridge off the East Coast will result in heat and humidity up and down the coastline for the next several days. The ridge in the Southwest will bring very hot conditions to the Southwest and especially the Southern Plains, where record highs are expected over the next several days. The Atypical part is across the Midwest. Normally, in between the two ridges of high pressure you’d have a trough of low pressure, but in this case, we actually have a closed upper-level low pressure system. While these are common in the fall, winter, and spring, they usually don’t occur much in the summer. This will bring cooler than normal conditions into the Midwest for the next few days.

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What is this, April? The upper-level pattern features ridges of high pressure in the Southwest and off the East Coast, and an upper-level low pressure system in the Great Lakes. Image provided by Pivotal Weather.

With high pressure anchored off the East Coast, a warm and humid pattern will set up for much of next week (and possibly longer). Notice that we said “warm”, and not “hot”. While temperatures will still be a little above normal this weekend into much of next week, highs will only be in the 80s to lower 90s for most of the Eastern US. While the temperatures won’t be that bad, humidity levels will. With high pressure anchored off the East Coast, a southerly flow will help moisture stream northward from the tropics right up the East Coast this weekend and into much of next week. Dewpoints will be in the upper 60s and 70s across the region, so even though temperatures may not be hot, it will feel oppressive across much of the region.

GFS Pressure Lev East Coast USA Precipitable Water
Moisture will stream northward from the tropics into much of the East Coast over the next several days. Loop provided by WeatherModels.com

 

With a warm and humid airmass in place for much of the week, it won’t take much for showers and thunderstorms to develop each day. With plenty of available moisture, some of these storms will end up producing very heavy rainfall. While the map above is a forecast that shows widespread coverage of heavy rain, in many cases, the storms will be very localized. Some locations could get hit by slow-moving thunderstorms over and over, while other spots a few miles away get little to no rainfall. Across the Mid-Atlantic States, where heavy rain led to flooding during the Spring, similar conditions are possible again for the next week. Across the Northeast, things are a little different.

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That’s a lot of rain from the Carolinas northward over the next week or so. Image provided by College of DuPage.

 

Here in New England, and in New York too, much of the Spring and early summer has been very dry. Localized thunderstorms have brought heavy rain to a few spots, especially earlier this week, but overall, rainfall has been well below normal across the area. Some relief will come this weekend. A weak low pressure system will move across the region late Saturday into Sunday as an upper-level low pressure system moves into the Midwest. The surface low will bring heavy rain and some gusty winds to parts of Southern New England and southeastern New York. The heaviest rain is expected late Saturday night into early Sunday morning, so neither day should be a complete washout. Once that system moves by, a warm and humid airmass will settle in, with a daily chance for showers and thunderstorms this week. Again, some places could get drenched, and some might get missed completely. Some could see off-and-on showers and storms for 6 hours, some could get a shower that lasts 6 minutes. Basically, it’ll be like living in Florida for a week, without having to worry about looking outside and finding an alligator in your swimming pool.

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It’s been very dry across New England and New York for a few months now, with drought conditions developing. Image provided by the National Drought Monitor.

 

Think warm and humid conditions with a daily chance of thunderstorms isn’t fun? It could be worse. Normally, it’s hot across Texas and the Southwest during the summer. This week though, the ridge of high pressure that is currently setting up across the Southern Plains and Southwest will bring in temperatures that are well above normal. In fact, record highs are expected for the next several days across much of Texas, as temperatures soar past 100 across much of the state, with some locations possibly exceeding 110 degrees. Unlike when the models were forecasting those temperatures here a few weeks ago, this time it’s going to happen. The heat won’t be confined to the Lone Star State either, with triple-digit highs also expected from parts of the Lower Mississippi Valley into the Southern Plains as well as parts of Colorado and New Mexico. There won’t be much, if any, relief at night either, as low temperatures will stay in the 70s, with many locations, especially urban areas like the Dallas-Fort Worth Metroplex likely not dropping below 80 degrees for low temperatures.

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Friday looks to be the hottest day across the Southern Plains and Texas, with many record highs expected to be broken. Image provided by WeatherModels.com

 

As we head into next week, the heat will ease a bit across Texas and the Southern Plains, but the core of the intense heat will shift westward into the Desert Southwest. High temperatures will top 110 degrees across much of the area for the first half of next week, with the usual hot spots such as Lake Havasu City, Arizona; Laughlin, Nevada; and Death Valley, California likely exceed 120 degrees during some of the afternoons. Highs will also top 100 across much of interior California once again. Anyone wanna place a bet as to whether Death Valley reaches 125? Better yet, will they have a night where the temperature doesn’t drop below 100 (it’s happened before)?

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A severe weather outbreak is possible on Friday across the Ohio and Tennessee Valleys. Image provided by the Storm Prediction Center.

Meanwhile, an upper-level low pressure area will settle into the Midwest. With the clash in airmasses along a cold front, showers and thunderstorms will develop. Some of these storms will become strong to severe on Friday, especially across the Ohio and Tennessee Valleys. The main threats with any storms that develop will be strong winds, large hail, and torrential rainfall that could trigger flash flooding. Some tornadoes are also possible. The storms may start during the morning closer to the Great Lakes, with the afternoon and evening seeing the most widespread activity across the region. While activity should weaken at night, the threat of severe weather will continue across southern and eastern parts of the region.

NAM-WRF 3-km null Simulated Radar
Strong to severe thunderstorms are expected across the Midwest on Friday. Loop provided by WeatherModels.com

 

As these storms crossed the Midwest today, they produced wind gusts to 90 mph and more than 30 tornadoes across Iowa. The town of Marhsalltown was devastated by a tornado earlier today. How bad was it? We’ll end this post with the Storm Report from the National Weather Service Office in Des Moines with the description of what happened in Marshalltown:

 

REPORTS OF CATASTROPHIC DAMAGE, INCLUDING 
VEHICLES MISSING, VEHICLES OVERTURNED, TOPS
OF BUILDINGS GONE, TREES DOWN, POWER LINES,
GAS LINES, ETC...

Winter’s Last Gasp?

We’ve reached Patriots Day weekend, which is usually one of the truest signs that winter is over and Spring has finally started in New England. This year that will not be the case. In fact, this year, Patriots Day weekend is going to be absolutely miserable.

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In mid-April, high temperatures should normally be in the middle to upper 50s around here. Image provided by Weathermodels.com

Don’t let today’s warmth fool you. Even though temperatures are in the 60s and even lower 70s away from the South Coast, big changes are coming, and not for the better. A backdoor cold front will drop down across the region late tonight and early Saturday, bringing much colder air back into the region. Temperatures are going to go slowly down through the 40s all day on Saturday and gusty northeast to east winds are going to make it feel even colder. By Saturday evening, temperatures will drop into the 30s, and they’ll likely stay there through most of Sunday. They may start to drift back up Sunday night and Monday, but it will still be on the chilly side. That’s the least of our problems.

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Temperatures on Sunday will be 15 to 25 degrees (or more) below normal. Image provided by Pivotal Weather.

A large storm system is going to bring severe weather to the Mississippi Valley and Gulf Coast today and tomorrow, while producing blizzard conditions in the Plains and Upper Midwest, with a significant ice storm expected in parts of the Great Lakes. That storm is going to slowly make progress eastward over the next few days, with the moisture from it likely arriving late Saturday. As we mentioned earlier, temperatures are going to be dropping into the 30s late on Saturday. If you combine that with incoming moisture, you get a giant mess.

Rain will develop late Saturday afternoon or evening across the region, but as temperatures continue to drop, some sleet will likely mix in, with freezing rain also a possibility, especially north and west of Boston where temperatures could even fall into the upper 20s Saturday night. Sleet and freezing rain will continue across much of the region for a good chunk of the day on Sunday, as temperatures will only rebound into the middle 30s at best for most of the area. The reason we’re expecting sleet (and freezing rain) and not snow, is that the colder air will all be at the lower levels of the atmosphere. It will actually be warmer aloft. We wouldn’t be surprised if the summit of Mount Washington is one of the warmest places in New England Sunday afternoon.

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This storm may drop quite a bit of sleet on the region Saturday night into Sunday. Image provided by WeatherBell.

Somewhat milder air will start to filter in Sunday night as low pressure moves into the eastern Great Lakes. This will change everything back over to a cold rain. For once, a cold rain is actually good news, because it means we don’t have to worry about the sleet any more. However, this is bad news as we head into Marathon Monday. As that low heads off to the north and west of the region, it will bring a cold front towards the Northeast. As warmer air surges northward ahead of the front, it will help bring some heavy rain into the area. That warmer air will mainly be aloft, but some of it could reach the surface during the afternoon. In the morning though, when the race starts, and the Red Sox are scheduled to play, we’ll likely have periods of heavy rain, with temperatures only in the upper 30s to middle 40s. Not exactly baseball or running weather. Temperatures could get into the 50s or even low 60s in the afternoon, especially south of Boston, but we’ll still have the heavy rain to deal with. The cold front moves through late in the day, and drier air starts to filter in on Tuesday. Even then, a few showers are still possible as an upper-level low pressure system moves across the Northeast.

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The GFS forecast is not pretty for the next few days. Stay inside, watch some playoff hockey, and remember that warmer weather is coming eventually. Loop provided by Tropical Tidbits.

So, is this it for winter? We’d like to say yes, but at this point, we can’t make that statement definitively. Longer-range models show below normal temperatures continuing into much of May. While it’s awfully tough to get wintry weather around here at this time of year, it’s not impossible. We have had heavy snow events in late April (1987), and early May (1977). As some of you may remember, in 2013, up to 3 feet of snow fell in parts of Northern New England and Upstate New York during Memorial Day weekend. So, we’d wait until at least mid-May before taking the flip-flops and shorts out of where ever you stored them for the winter.

 

A Saturday Night Special

The last few days have been fairly mild around here, and even milder air is coming in for the first half of the upcoming week. So naturally, we’re talking about a snowstorm for tonight.

Low pressure is over the Tennessee Valley at midday, and will quickly move towards the Mid-Atlantic coastline this evening, passing south of New England as it intensifies tonight. Even though the sun is shining now, clouds will quickly move in this afternoon, with snow developing late this evening, around 9pm or so, give or take an hour. Snow will continue overnight, with the possibility for some briefly moderate to heavy snow. Since most of you will be sleeping, this shouldn’t cause too many problems. A change to rain seems likely across parts of Cape Cod and the Islands, possibly even into extreme southeastern Massachusetts.

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Forecast for the progression of the storm based on the NAM model. Loops provided by Tropical Tidbits.

Everything winds down near or a little after daybreak. For most of us, a general 3 to 5 inches of snow is expected, with a few spots possibly seeing 6 or 7 inches. Across Cape Cod, where a change to rain is likely, amounts of 1 to 3 inches seem more plausible at this time.

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

The snow won’t last too long though. The sun will return Sunday afternoon, with temperatures getting up into the 40s. That will help to quickly melt a lot of what fell overnight. Temperatures will drop back below freezing Sunday night, so things may ice up once again. Use caution if you’re heading out for anything. Even warmer weather is heading in for the start of the week. A warm front will move through on Monday, with some showers preceding the front late in the day. Once the front moves through, unseasonably warm conditions are expected for Tuesday and especially Wednesday. On Tuesday, high temperatures should get into the upper 50s and 60s away from the South Coast. On Wednesday, we could challenge some record highs, with some places possibly making a run at 70 degrees. A cold front will move through late in the day on Wednesday, bringing an end to the warm weather, so enjoy the early taste of Spring while it’s here.

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Yes, temperatures could reach or exceed 70 in parts of the region on Wednesday. Image provided by Weathermodels.com

Thursday Will Not Be a Fun Day

So, as you may have heard from the relentless media hype over the past few days, we’ve got a storm headed our way on Thursday. While this will be an extraordinary storm for places like Florida, Georgia, and the Carolinas, up here, we’ve seen a lot worse.

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Snowfall accumulations of 2-5 inches from northern Florida into eastern North Carolina? That doesn’t happen too often. Image provided by Weathermodels.com

Snow and sleet have been falling today across portions of northern Florida, Georgia, and South Carolina. Several inches are expected to fall today, especially along the coastline. Given how rarely this happens in some of these locations, it will probably bring the region to a halt, while those of us in the North point and laugh. Don’t worry, our time is coming tomorrow.

The storm that is producing the snow down South will move up the East Coast later today and Thursday, rapidly intensifying as it does so. You may have heard the terms “bombogenesis” or “weather bomb” used as part of the media hype in the last few days to describe this storm. These are terms that have been around for quite some time. Bombogenesis happens when the lowest pressure of a storm drops more than 24 millibar in a 24 hour period. This happens several times a year with storms off the East Coast. It is nothing out of the ordinary. The reason this storm is getting the attention, aside from the Southern snow, is that the pressures are much lower than a typical winter storm. This will be a strong storm system, but again, we’ve had powerful storms off the East Coast plenty of times before.

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Definition of “bombogenesis”. It’s a fairly common occurrence. Image provided by Weather.com

As the storm gets cranked up off the East Coast, it will generate strong winds,, especially along the coast. While we’re looking at wind gusts to 40-50 mph, possibly even higher, things could be a lot worse. We don’t have a large high pressure system to our north (more on that in a minute). If we had a high to our north, increasing the pressure gradient between the storm and the high, winds would be even stronger. The tighter the gradient, the stronger the winds. This is why we can have strong winds with weaker systems, if there is a large high in place to the north.

Along with the winds, coastal residents also have to worry about coastal flooding. Since we’re just past the full moon, tides remain astronomically high. Add in strong onshore winds, and residents along north to northeast facing beaches could experience some coastal flooding around the midday/early afternoon high tide on Thursday. By the time we get to the high tide Thursday night, winds will have shifted into the west or northwest, thus limiting the flooding potential.

Back to the high pressure, or lack thereof, to our north. High pressure has been sitting to our north or northwest all week, which is why we’ve been frigid since before New Year’s. That high has shifted offshore now, allowing somewhat milder air to settle in today. Normally, to get heavy snow, we need that high pressure area to stay to our north or northwest, to lock the cold air into place. With that not the case this time, we’re going to have to deal with a rain/snow line. That seems hard to believe given how cold the past week has been, but it is the case. Water temperatures are still in the lower 40s off our coast, so a strong onshore wind will warm up the lowest layers of the atmosphere enough for a change to rain. This seems like across Cape Cod, but the question becomes, how far inland does that rain/snow line penetrate? The models have varying ideas on this, but a portion of southeastern Massachusetts may see a changeover.

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Winter Storm Warning are in effect for virtually the entire East Coast, with Blizzard Warnings (in red) for parts of coastal New England. Image provided by NOAA.

So, we’ve talked about strong winds, coastal flooding, and a rain/snow line. Now, for the only part that most of you are interested in – snow. First, we’ll talk about the timing. Snow should develop from south to north across the region between about 3 and 6am. So, by the time most of you wake up, it will likely be snowing. The snow will end between 7 and 10pm for most of us. The worst of the storm will be between about 9am and 4pm. Snow will be moderate to heavy at times, which combined with strong winds, will create whiteout or blizzard conditions, especially along the coast. If you don’t have to be out tomorrow morning/afternoon, we’d recommend staying where you area. Blizzard warnings have been posted for parts of eastern and southeastern Massachusetts, the NH Seacoast, as well as coastal and Downeast Maine. Remember, the amount of snowfall has absolutely nothing to do with blizzard conditions. You can have a blizzard with no snow falling at all. By definition, you have a blizzard when visibility is 1/4 mile or less due to falling or blowing snow and you have sustained winds or gusts to 35 mph or more for 3 consecutive hours or more.

So, how much snow are we looking at? There isn’t really one model that we completely agree with, so we’re going with a blend of the ideas. Because the storm will be moving along fairly quickly, we’re not looking at any blockbuster amounts. The trickiest part is where the rain/snow line sets up.  Right now, we’re thinking somewhere close to the Cape Cod Canal. As for amounts, here’s the breakdown:

Outer Cape Cod/Islands: 3-5″
Upper Cape Cod: 4-8″
Southeastern Massachusetts (south and east of I95): 8-14″
Northern RI/Interior Eastern Massachusetts/North Shore: 6-12″
Central Massachusetts/Merrimack Valley/Southern NH/Seacoast: 5-9″

The biggest wild card is Southeastern Massachusetts, especially the closer to Cape Cod you get. The farther the rain/snow line moves inland, the less accumulations will be. This is the area of biggest “bust potential”.

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The Canadian HRDPS model is probably closest to our thinking, but not exactly the same. Image provided by WeatherBell.

Once the storm moves by, we’ll slowly clear out on Friday, but gusty northwest to west winds will usher another arctic blast into the region. Saturday may be even colder than any of the days we’ve had over the past week. Especially with fresh snowcover, temperatures will plunge again, with the worst of it on Saturday, when high temperatures likely stay in the single digits. Sub-zero lows are likely across much of the region Saturday morning and especially Sunday morning.

Summer Arrives (in the East)! Winter’s Back (in the Rockies)!

The current weather pattern across the country is one that is fairly typical of Spring. However, the results of that pattern are Winter in the Rockies and Summer in the East. In between, there is plenty of severe weather, which is fairly typical of Spring.

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A ridge in the East, a trough in the West. Not that uncommon of a pattern. Image provided by College of DuPage.

An upper-level low pressure area will move out of the Pacific Northwest and into the nation’s midsection over the next few days. While one storm system moves into the Upper Midwest today, a second one will develop east of the Rockies and move into the Plains states on Thursday. With cold air moving in behind these systems, and warm, moist air flowing northward from the Gulf of Mexico ahead of them, strong to severe thunderstorms are likely again for the next few days across the Plains states.

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Thursday could be a very active day for severe weather in the Central and Southern Plains. Image provided by the Storm Prediction Center.

Severe weather has plagued the Plains states and Great Lakes for the past few days, with over 500 reports of severe weather between Monday and Tuesday. Nearly 30 tornadoes were reported, along with hail as large as softballs, and hundreds of reports of wind damage from gusts as high as 85 mph.

 

Behind the low pressure area, a late-season snowstorm is expected across the Rocky Mountains. Heavy snow will continue across portions of Montana and Idaho today, spreading into Wyoming and Colorado for Thursday into Friday. Across the higher elevations, totals of 1-3 feet are expected, which will keep the ski season going for a while longer. Snow may also spread into the High Plains of eastern Colorado and western Nebraska, with some minor accumulations possible. In Denver, it looks a couple of slushy inches may fall, though at least 1 model is forecasting much heavier amounts. In a normal year, Denver averages 1.7″ of snow, and the city has seen measurable snow during the month of May in 11 out of the last 16 years, so snow in May is not uncommon, though a heavy snowstorm, if it materializes, would be. Denver has only received 10 or more inches of snow in the month of May 6 times in a 135 years of records, with a record total of 15.5″ set back in May of 1898.

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A late-season snowstorm may drop up to 3 feet of snow in the higher elevations of the Rockies. Image provided by WeatherBell.

Meanwhile, in the East, an early taste of summer is ongoing, thanks to a ridge of high pressure aloft, and a surface high pressure area off the East Coast. Temperatures soared into the 80s and lower 90s on Wednesday, setting several records, but the hottest day for many locations will be Thursday. High temperatures will climb into the lower to middle 90s in many locations, likely breaking records across much of the region. When you combine the heat with dewpoints well into the 60s, it will definitely feel like a mid-summer afternoon across the region. A cold front will move through the area of Friday, possibly triggering a few showers and thunderstorms, but also sending temperatures back to where they should be in the middle of May.

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A lot of record high temperatures may be broken across the Northeast on Thursday. Image provided by WeatherBell.

Welcome Back Winter

It seems as though we went through this last week, but once again, after a taste of early Spring, Mother Nature is about to remind us that March can still bring plenty of wintry weather to the area.

Today is the transition day, as strong winds usher much colder air into the region behind a cold front that crossed the region late Wednesday night. While temperatures are still in the 40s, things are about to change, and most of you probably won’t like it. That cold front will stall out south of New England today, and low pressure will ride along it across the Mid-Atlantic states, passing south of us on Friday. Meanwhile, high pressure will build in north of New England, bringing plenty of cold air with it. Let’s see now, cold air moving in from the north and moisture moving in from the south. What happens when you combine those? That’s right, you get SNOW! Luckily, we’re not looking at a lot of snow this time. Let’s get to the details:

Snow should start to develop early in the morning, possibly even starting as a little rain across Cape Cod and southeastern Massachusetts. The snow may fall at a pretty good clip during the morning hours, tapering off and ending during the afternoon.Since we’re into mid-March, the sun angle is roughly the same as the end of September. In other words, fairly strong. So, once we get past sunrise, even though it’ll be cloudy, the snow will have a tougher time sticking to paved surfaces. That’s the good news. The bad news is that a lot of the snow will fall before then, so the roads may not be that pretty for the morning commute.

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Forecast from the NAM model for the progression of Friday’s storm. Loop provided by Pivotal Weather.

OK, so the snow ends in the afternoon and we’re done right? As noted college football analyst Lee Corso used to say “Not so fast my friend”. As the storm moves into the Gulf of Maine, a piece of energy, called a Norlun trough (Explained here by Matt Noyes), may produce some additional light snow from the North Shore up into southern New Hampshire and south coastal Maine through the evening hours. It won’t amount to much, but could be just enough to screw up the evening commute well north of Boston.

So, how much snow are we looking at? North of the Mass Pike, probably less than an inch, if any snow falls at all. From the North Shore into Boston and it’s immediate southern and western suburbs, probably 1-2 inches. For the South Coast, roughly south of Route 44, 2-4 inches should do it, with a little more possible across parts of the Cape and Islands.

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The High Resolution NAM model most closely matches our thinking with regards to snowfall on Friday. Image provided by WeatherBell.

All in all, not a big deal, especially by New England standards. What will be a big deal is the cold air behind the storm. Similar to last Saturday, this Saturday will be quite chilly, especially with fresh snowcover. High temperatures may struggle to get into the lower 20s, but wind chills will be in the single numbers and below zero. So, if you’re heading outside, make sure you bundle up. It’ll feel more like January than March.

Finally, we’re aware of the uncontrolled hype on the Internet (and TV) about a potentially major snowstorm on Tuesday. Right now, it’s a potential storm and nothing else. We’ll certainly keep our eyes on it, and if a threat does materialize, we’ll let you know well in advance. For now though, it’s nothing more than a figment of the computer models’ imaginations. We don’t participate in hype or speculation here at StormHQ, so we’re going to leave it at that.

In Like a Lion…

The old saying is that March comes in like a lion and goes out like a lamb. We’ll see about how it goes out, but it certainly looks like it’s going to come in like a lion this year, but not in the usual way.

We’ve got some unseasonably mild air already in place, but it’s going to get even warmer as a warm front moves across the region tonight. It’ll be accompanied by some showers, and maybe even a rumble of thunder when it moves through. Some of the rain overnight may be locally heavy, but since most of you will be sleeping when it comes through, you won’t even notice. Also, with the warm front coming through, we’ll have our low temperatures this evening instead of in the morning, as temperatures will slowly rise overnight.

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Plenty of record highs are expected across the Northeast on Wednesday. Image provided by WeatherBell.

 

This brings us to Wednesday. Once that warm front moves across the area, even warmer air will flood into the region, with highs again soaring well into the 60s. The only limiting factor for tomorrow will be cloud cover, which there will likely be plenty of. If we can get some breaks of sunshine, it wouldn’t be a surprise if temperatures made a run at 70 in spots.

Warm temperatures aren’t the only story for Wednesday though. A strong cold front will be approaching from the west. While this front will bring an end to our warmth Thursday morning, it’s what happens ahead of it that is a bigger concern.

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A slight risk for severe weather exists across parts of southwestern New England on Wednesday, with a marginal risk for most of the remainder of Southern New England. Image provided by the Storm Prediction Center.

 

As is usually the case during the warmer months, with a warm and relatively humid airmass in place, the atmosphere will become unstable. Add in some lift ahead of the front and you get showers and thunderstorms. The bigger the clash in airmasses, but stronger the storms. That’s what will happen tomorrow. Thunderstorms will develop ahead of the front during the afternoon and evening hours and may even continue into the nighttime ahead of the front. Some of the storms could become quite strong, with heavy downpours, frequent lightning, and damaging winds. There is even the chance for an isolated tornado. Just last week, a tornado touched down in Goshen and Conway, Massachusetts – the first confirmed tornado ever during the month of February in the Commonwealth.

 

New England isn’t the only place where severe weather is expected though. In fact, what’s expected up here is minor compared to the Ohio and Mississippi Valleys. As that cold front moves into those areas later today into early Wednesday, widespread severe weather is expected to develop. Large hail, heavy downpours, damaging winds and several tornadoes are expected. This is more typical of April than the last day of February.

After this front moves offshore, things quiet down a bit, and we get back into weather that is more typical of early March, especially here in the Northeast. We do need to keep an eye on Friday though. An Alberta Clipper will be diving southeastward from the Great Lakes. It will pass south of New England during the day on Friday and into Friday morning. While the majority of the forecast models keep the system far enough south of have little to no impact on us, not all of them do. So, there is the chance for some light snow, especially south of the Mass Pike, on Friday. We’ll have more on this later in the week if the threat materializes.