Tag Archives: snow

A Wintry Mess Midweek Next Week

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Hello everyone!

With today’s Norlun trough fizzling out over the Midcoast and cold air pouring in as forecast, attention can now turn to a mid-week mess due to arrive Tuesday across the area as low pressure passes over the region. Because the low will be passing over us and not to our east, this will be a mix event with a medley of precipitation types including but not limited to rain, snow, sleet, and freezing rain. I’ve covered tonight and tomorrow’s bitter cold several times in the last few days so refer to last night’s blog post for the most recent info on that. Nothing has changed since then. With that said, let’s dig into the Tuesday storm.

12Z GFS Showing The Setup For Tuesday. Image Credit: Weatherbell
12Z GFS Showing The Setup For Tuesday. Image Credit: Weatherbell

The Arctic high pressure containing the bitter cold we feel tonight and tomorrow moves offshore Monday bringing behind it warm SW winds. Temps will rise on Monday but keep in mind, they have a lot to rise as temps Sunday remain largely below 10 degrees. The airmass ahead of the storm is also extremely dry so there will be room for evaporational cooling at the onset of precip. I think we get a good burst of snow at the start of the storm across the area before warm air intrudes from south to north (this looks like a solid front end thump event for those familiar with New England weather terminology). How far north that warm air makes it and how fast it makes it there will determine precip type and thus what accumulations will end up being.

12Z GFS Showing The Arctic High Moving Offshore Monday Evening Leaving In Its Wake Warm Southerly Winds. Image Credit: Accuweather
12Z GFS Showing The Arctic High Moving Offshore Monday Evening Leaving In Its Wake Warm Southerly Winds. Image Credit: Accuweather

How do we go from 20 below zero to rain in a matter of days? The answer lies in the placement of the Arctic high pressure. Notice how the high has departed to the east on Monday and behind it, warm southerly winds are already eroding the cold in place long before the storm gets to us. This is why I’m not super bullish on cold air remaining locked in. That being said, I’ve learned over my time forecasting in Maine that cold air has tremendous sticking power and is not easily moved. This is why I think the mountains stay mainly snow while the rest of the area only briefly sees rain with the exception of the coast where there will be more rain.

12Z GFS Highlighting A Rough Idea For Dominant Precip Type Tuesday Afternoon. Image Credit: Accuweather
12Z GFS Highlighting A Rough Idea For Dominant Precip Type Tuesday Afternoon. Image Credit: Accuweather

In terms of what sort of precip will fall from the sky, the short answer is too early to tell exactly. However, I do feel comfortable roughly outlining my thoughts for general precip type. I think the mountains is mostly snow as the low passes over the coastal plain. They look to remain on the cool side of the low and even if the low passes over the mountains, I think you’d be hard pressed to get enough warm air that far north-west to allow for an extended period of rain. I do think though that the mountains mix with some sort of sleet/freezing rain at some point. The coast is the other higher confidence forecast (relative to the storm in general, confidence is medium at best with any aspect of the storm). The low would have to track significantly farther south than forecast for cold air to remain in place throughout the storm. For coastal areas, look for snow changing to a mix then changing to rain with briefly heavy rain possible. For inland areas, expect some sort of a mix with snow at the onset and rain to finish. What happens in between is anyone’s guess. Confidence will increase in the coming days so stay updated for the latest info.

I’ll try to have an initial guess at accumulations tomorrow evening in my next update on the storm. I’ll have tomorrow’s forecast as usual tomorrow morning.

-Jack

 

Cold, Windy, And For Some Snowy Today

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Hello everyone!

Today will feature mainly cloudy skies, cold temps, high winds, and snow as winter finally shows up in a real capacity at least for a couple days. Look for highs today to struggle into the single digits above zero north and the 10’s south late morning before dropping below zero area-wide tonight. Lows tonight will be dangerously cold with actual temps of 15 to 25 below north and 5 to 15 below south teaming up with 25mph NW winds to create downright dangerous wind chills. Wind chills in the mountains will range from -30 to -50 (colder at elevation, the summits above 4,000 feet willl see even more extreme wind chills) while the coast and foothills see wind chills ranging from -20 to -40.

Across the midcoast, things get really interesting today as a Norlun trough develops. 6-10″ of snow is likely wherever it sets up and thumps though it remains to be seen exactly where that is. I went into detail about the forecast and also about how Norlun troughs work in my blog post last evening which includes my snowfall forecast. Farther west, snow showers and flurries are possible today but accumulation will remain under an inch with the exception of the mountains where a few inches of upslope are possible.

I’ll have more updates on the cold tonight and a messy storm threat for midweek this evening.

-Jack

Midcoast Snow Tomorrow, Cold For All Sunday

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Hello everyone!

Cold air is firmly entrenched today but even colder air is on the way. Look for a cold front to smash SE tonight bringing behind it the coldest air all season and the first truly Arctic air we’ve seen all season. As the cold air moves in, an upper low diving to our south will set the stage for a Norlun trough event along the midcoast tomorrow. Beyond that, bitter and dangerous cold arrives Sunday followed by a messy storm midweek next week.

Saturday Norlun Trough

12Z GFS Showing The Setup For Tomorrow. Image Credit: Weatherbell
12Z GFS Showing The Setup For Tomorrow. Image Credit: Weatherbell

The front gets hung up along the midcoast as the upper low slides to our south. Winds out ahead of the 500mb trough will turn southeasterly and eventually easterly which will provide a mechanism for moisture to be transported into the region. Also, with southeasterly winds aloft, there will be nothing to move the trough once it sets up. Most of us will see the moisture transport aloft in the form of light snow/snow showers during the day tomorrow with light accumulations. The midcoast will be the only area to really capitalize on that. To understand why, read the next paragraph about how Norlun troughs work. If you’re more interested in the forecast, skip on down to the next picture and read about the cold coming Sunday.

A Look Behind The Scenes At Norlun Troughs

Here is a graphical explaination of a Norlun trough I did for UpPortland. Notice that tomorrow the trough will be over the Midcoast rather than Portland. All poor image design credit goes to me (and Frontpainter for the map)
Here is a graphical explanation of a Norlun trough I did for UpPortland. Notice that tomorrow the trough will be over the Midcoast rather than Portland. All rough image design credit goes to me (and Frontpainter for the map)

Because it’s been so warm recently, the ocean is still quite toasty. This sets up a very large difference in temperature between the warm ocean and the cold air. The warm water will heat the lowest level of the atmosphere creating warm air which wants to rise. Above this very shallow layer of relative warmth lies an entire atmosphere of very cold air which wants to sink. Somewhere in the impenetrable fortress of cold, there will be a weakness. The warm air will rush upwards through this weakness generating tremendous upward motion and leading to warm moist air crashing into cold dry air. This violent collision will produce snow.

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A Cross Section Of The Atmosphere Showing The Dynamics Involved With The Trough. More Rough Image Design By Me.

As the new trough takes up the energy immediately near it, warm air trapped under the cold air all across the Gulf of Maine will rush in to take its place so it too can rush upwards and cool. As the trough is using up the existing warm air, new warm air will keep being created as the water continues to warm the lowest levels. This warm air will rush to the weakness in the cold and rise up, depositing its moisture along the way. This is what we call a Norlun trough.

One of those will form over the midcoast and deposit heavy snow tomorrow. Totals are likely to come it at around a foot in the core of the trough but it remains to be seen exactly where that sets up. These events are notoriously fickle and can set up wherever they please or not at all. One good example happened just last night when a weak Norlun formed over Portland out of left field causing major issues. Bottom line: expect the unexpected.

Expected Snowfall. Notice The Sharp Cutoff Which Leads To High Uncertainty From Brunswick On East To Rockport.
Expected Snowfall. Notice The Sharp Cutoff Which Leads To High Uncertainty From Brunswick On East To Rockport.

Expected snowfall for tomorrow. Upslope snow showers in the mountains are likely to produce 1-3″ in the usual spots. Farther south, a dusting to as much as 2″ is possible with isolated snow showers/flurries. In the core of the Norlun, thundersnow is possible as there will be a solid amount of instability associated with the temperature falling dramatically with height from the warm ocean to the bitter cold air moving in aloft (technical: lapse rates will be very impressive).

NW winds will be howling tomorrow beginning in the afternoon. While blowing and drifting snow will initially not be an issue, by Saturday night, those who saw snow will also see it blowing around leading to more slick spots and reduced visibility. It will also add an extra sting to the air if you happen to be out and about Saturday night.

Dangerous Cold Sunday

18Z GFS Showing Dangerous Cold Sunday Morning. Credit: Weatherbell
18Z GFS From Yesterday Showing Dangerous Wind Chills Sunday Morning. Credit: Weatherbell

Very cold air is still on track to come into the area behind the storm on Sunday. Actual temps will drop well below zero and as NW winds howl at over 25 mph, wind chills will drop even lower. This is the image I used for last night’s post and it still applies as wind chills approach -40 to -50 in the north with -20 to -30 degree wind chills in the south. Bundle up for the Valentines Day dates both Saturday and Sunday nights. Thankfully, the extreme cold is out on Monday.

Messy Midweek Storm

12Z GEFS Showing The Range Of Possible Outcomes And The Lack Of Confidence Regarding The Forecast At This Point. Image Credit: Weatherbell
12Z GEFS Showing The Range Of Possible Outcomes And The Lack Of Confidence Regarding The Forecast At This Point. Image Credit: Weatherbell

As the cold retreats, we have another storm threat. We are virtually certain to see precip the question is of what variety. Right now, it looks like a mess with all precip types possible for everyone. It is far too early to nail down exact impacts or amounts but total accumulation of whatever falls could be significant. My thinking from yesterday still applies in that uncertainty remains large here. One group of forecast models leans towards a colder, farther east solution with more snow than mix while another camp of models leans towards more rain and mix than snow.

Another storm is on the horizon late next week but we have to get the first two resolved before we can dig into that one. Just know that there is the potential for a storm and as always, ignore any hype you may see.

I’ll have more updates in the coming days as the midweek storm becomes clearer. I’ll also be on Twitter watching the Norlun trough evolve tomorrow @JackSillin.

-Jack

A Tale Of Two Cold Fronts Today

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Hello everyone!

Today will feature a mainly sunny start with fairly mild temps as cold front number one clears the coast, removing the moisture from last night (not that there was that much of it). Cold front number two blasts south today bringing the chance for heavy snow in the form of snow showers and squalls. A coating to as much as 2″ of accumulation is possible where these squalls form.

HRRR Model Giving A General Idea Of What To Expect In Terms Of Squally Weather This Afternoon. Credit: Weatherbell
HRRR Model Giving A General Idea Of What To Expect In Terms Of Squally Weather This Afternoon. Credit: Weatherbell

Here is the general idea of how things play out this afternoon. Don’t take this too literally in terms of exactly who gets a burst of snow but know it’s definitely possible especially in southern areas. Heavy snow could briefly cause low visibility and slick up roads for the evening commute.

-Jack

Bitter Cold Moves In This Weekend, Snow Possible Out Ahead Of It

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Hello everyone!

Another update this evening looking at a bitter cold blast this weekend which will be bookended on either side by snow threats. Let’s start with the snow threat on the front end of the cold air which arrives Saturday.

Saturday Snow

12Z GFS Showing Saturday's Setup
12Z GFS Showing Saturday’s Setup. Image Credit: Accuweather

Saturday’s storm threat really hinges on how far south an upper low digs and how fast its attendant surface low develops. Right now, Downeast areas look best in terms of everything pulling together in time for a sizeable snow event. Here in Western Maine, I think this is more of a one and done blast where a quick several inches are likely to fall. The timing on this would be later in the day on Saturday though the details are still to be ironed out.

Sunday Cold

12Z GFS Showing Dangerous Cold Sunday Morning. Credit: Weatherbell
12Z GFS Showing Dangerous Cold Sunday Morning. Credit: Weatherbell

The core of the bitter cold arrives Sunday with dangerously cold temps on the order of lows around 20 below in the north, 10 below in the south. Highs likely don’t make it to 0 in the mountains on Sunday while the coast struggles to 10 above. Wind chills will remain in the -40 to -20 range region wide Saturday night into Sunday. Yeah, this is the real deal.

Next Week Storm Chance

12Z GEFS Showing The Threat For A Snow Event Next Week
Yesterday’s 12Z GEFS Showing The Threat For A Snow Event Next Week. Credit: Weatherbell

As the coldest of the cold retreats early next week, the door is open for more snow. My thoughts on the threat remain unchanged from Yesterday and current solutions range from ice/rain to out to sea. Here’s the graphic I posted yesterday evening that shows the spread as well as which scenario has the most credibility as of now (the snowstorm scenario). This is still a while away so things will definitely change. Be sure to stay updated as to the latest forecasts.

More updates tomorrow.

-Jack

A Cold And Unsettled Week Ahead

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Hello everyone!

I thought I’d take a minute this evening to go over the next week or so of weather taking a quick look at what to expect. This will be a tale of a classic New England winter with snow, bitter cold, and the potential for a sizeable storm. Let’s start with the light snow which arrives tomorrow.

Light Snow Tomorrow 

12Z GFS Outlining The Light Snow Threat Tomorrow. Image Credit: Weatherbell
12Z GFS Outlining The Light Snow Threat Tomorrow. Image Credit: Weatherbell

A storm will pass well offshore tomorrow but an upper low still lurks to our west. Much like with our last storm, there will be a moisture transfer between the two storms. However, both storms will be weaker this time around especially the offshore storm (weak wave compared to powerful bomb). Therefore, the same concept applies but with less snow. Spotty snow showers will impact most but they will be hit or miss. The midcoast could get brushed with a bit of steadier light snow. A coating-2″ is forecast for everyone but 3″ is possible in the mountains and along the midcoast.

Bitter Cold For Valentines Day

12Z GFS Showing VERY Cold Air Over The Region Sunday. Credit: Weatherbell
12Z GFS Showing VERY Cold Air Over The Region Sunday. Credit: Weatherbell

An Arctic front blasts south Saturday and frigid winds bring in very cold air behind it. Lows Sunday morning are likely to drop well below zero into the 20’s below up north and the 10’s below in the south. The map shows temps at 5,000 feet so don’t panic with the -30C temps across Maine but do realize this is the real deal with dangerous cold on Sunday. Highs on Sunday will struggle to get above zero across Maine and New Hampshire and probably won’t in the mountains. The coldest air arrives just in time for Valentines Day so plan accordingly. Thankfully, the brutal cold moves on heading into next week though it does leave us a parting gift in the form of a storm threat.

Snow Threat Returns Next Week

12Z GEFS Showing The Threat For A Snow Event Next Week
12Z GEFS Showing The Threat For A Snow Event Next Week

As the bitter cold retreats, a storm will likely try to form somewhere. At this point, all solutions are on the table from Rain to OTS though the general consensus is for some type of snow event. This is too far out for specifics but just know that at some point in the middle of next week, there could be a snow event.

I’ll have more updates tomorrow.

-Jack

Snow Continues Tonight, Departs Tomorrow

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Hello everyone!

Snow is currently falling across the region with light to moderate being the dominant intensity. Look for this to continue through the night along with high winds that will blow the snow into a low visibility, drift inducing frenzy. Amounts in your front yard will range from 0-24″ when drifts are included. The actual amount of snow that will fall from the sky is likely to be in the 4-8″ range along the coast and in the 2-4″ range inland though with drifts, amounts will be far different when you look outside tomorrow morning.

HRRR Model Showing The Evolution Of Light Snow Tonight Through Early Tomorrow Morning. Credit: Weatherbell.
HRRR Model Showing The Evolution Of Light Snow Tonight Through Early Tomorrow Morning. Credit: Weatherbell.

Here is the HRRR model with a general idea on the evolution of the snow through tomorrow morning. I suspect it may be a little quick to shut off the snow as the upper low to our west will be eager to continue pulling in moisture. I think mid to late morning is a more reasonable stop time with drying from SW to NE.

Snowfall amounts from last night still look good with 4-8″ for most, 2-4″ in the mountains.

Check out last night’s post and this morning’s post for more info. That information still applies as the storm is progressing as forecast.

Snow showers are possible throughout the week as waves of low pressure develop well offshore. Another chance for respectable snow arrives early in the weekend next weekend followed by a blast of truly Arctic air early next week.

-Jack

Prolonged Light Snow On Track Today

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Hello everyone!

Everything is lining up as forecast and a long duration light snow event is likely today. Snow looks to arrive around noon here in Maine, a little earlier along the coast, and a little later inland towards the mountains. Not much has changed since yesterday in terms of expected snowfall. I still think the coast has the best shot at hefty snowfall amounts. Keep in mind, snow will be able to accumulate quite efficiently despite snow never falling that heavily. The good news with the light snow is that it will be easily moved by your shovel. The bad news is that it will be equally easily moved by the strong winds today that will gust along the coast to near or over 30mph. As a result, expect blowing and drifting of the snow not only that is just falling, but also of the 6″+ of snowpack most coastal areas have left over from Friday’s storm. This is likely to cause visibility issues especially for the evening commute.

HRRR Model Showing Heavy Snow Remaining South But Light Snow Impacting Maine Today. Credit: Weatherbell
HRRR Model Showing Heavy Snow Remaining South But Light Snow Impacting Maine Today. Credit: Weatherbell

Here is the HRRR model just to give you an idea of how the storm plays out in general. Don’t take it word for word in terms of individual bands or timing down to 15 minutes but look at it to get the general idea of the heavy stuff remaining south and the light stuff sitting over us for a while.

Temps today will be in the 10’s and 20’s.

Snow winds down tomorrow afternoon though snow showers will continue through Thursday as various pieces of energy rotate around an upper trough to our west.

-Jack

Long Duration Light Snow Event Arrives Tomorrow

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Hello everyone!

A powerful storm is bombing out over the ocean near the Carolinas this evening and we will be on the far western edge. At the same time, a complex upper low is diving SE across the upper Midwest. They will form a connection of sorts that will transport warm moist air over the cold air moving in tonight following today’s cold front.

12Z GFS Showing Mositure Connection Between Clipper And Coastal Storm. Image Credit: Accuweather
12Z GFS Showing Mositure Connection Between Clipper And Coastal Storm. Image Credit: Accuweather

The coastal monster will stay mainly offshore but it will throw a ton of moisture back to the NW. There is a clipper to the NW which is ready to receive this moisture and will help draw it back NW. Bottom line: there will be a feed of moisture over the area tomorrow as moisture from the coastal low gets pulled back into the clipper. If you watched my video discussing the Friday storm, you know that we need three things for snow: moisture, cold, and lift. We got the cold today with that Arctic front and above is the moisture. The problem though is the lift.

GFS Model Showing Broad But Light Lift Tomorrow Evening
12Z GFS Model Showing Broad But Light Lift Tomorrow Evening. Image Credit: Accuweather

As the warm air providing the moisture rises up and over the cold air at the surface we got today, it will rise, cool, and condense into precip. Sometimes, this mechanism for forcing (getting air to rise) can be quite effective in producing heavy precip. Not so much this time. If you’ve followed along for a while, you’ll know that I use Vertical Velocity to show how much air is rising and thus how heavy precip will be. In the big storms, you’ll often see bright purples and reds (notice scale on right of image). This time, we see yellows and oranges. This is indication that there will be less mesoscale banding and more broad lighter precip. Therefore, look for lighter snow though it will last long enough for fairly heavy accumulations.

12Z GFS Showing Gusty Winds Tomorrow Afternoon. Credit: Accuweather
12Z GFS Showing Gusty Winds Tomorrow Afternoon. Credit: Accuweather

This snow will be light and dry which is nice for shoveling but will be unfortunate because the gusty winds will have no problem blowing around the light, fluffy snow. For this reason, expect blowing and drifting snow to cause visibility issues especially tomorrow afternoon (map valid 1PM tomorrow). Winds are likely to range from near calm in the mountains to over 30mph at the coast.

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Here’s what I expect in terms of total snowfall. Keep in mind, this falls over a near 30 hour period from late morning tomorrow through Tuesday afternoon. Slow and steady is the name of the game for this one.

I’ll have more updates tomorrow.

-Jack

 

Tricky And Snowy Setup Tomorrow Night Into Monday

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Hello everyone!

After a nice little storm today, we turn sunnier and cooler tomorrow as low pressure moves east. Another low is already developing in the Gulf of Mexico and will be moving offshore well to our SE Monday. Normally, this would be a slam dunk miss but a strong upper low will be driving SE and there’s a lot of energy on the leading edge. Surface low pressure will develop over the Great Lakes in response to the upper low and a surface trough will develop between the Great Lakes low and the offshore low. This sets up a tricky forecast for Monday as this trough could take on some Norlun traits leading to narrow and possibly heavy snow bands.

12Z GFS Showing A Very Favorable Setup For A Norlun Event. Image Credit: Accuweather
12Z GFS Showing A Very Favorable Setup For A Norlun Event. Image Credit: Accuweather

Looking at the 500mb setup, there are a lot of things going for a Norlun event. A strong upper low is moving in from the NW and on the leading edge, a strong peice of energy is moving right over us. Also, being ahead of the upper low, the flow aloft is divergent. To put this in simpler terms, the air at 20,000 feet is spreading out. This leaves a void that air from below must rise to fill. Think of what happens when you pull your hands apart on the surface of a lake or bath. Water rises to replace the water you pushed to the side. This rising motion helps generate precip. This is how everyone will see a coating to an inch or two of snow tomorrow night into Monday morning. The real fun is along the southern coast with a Norlun trough.

18Z RGEM Showing The Surface Setup Monday Morning. Image Credit: Weatherbell
18Z RGEM Showing The Surface Setup Monday Morning. Image Credit: Weatherbell

At the surface a storm will blast by well SE tomorrow. Another weak wave will develop over the great lakes. The link between the two will manifest itself in the form of a Norlun trough extending NW-SE across the area. Everyone sees light snow from synoptic (large) scale divergence aloft but any moderate snow amounts will be dominated by a mesoscale (small) norlun trough. These troughs generate narrow, heavy snow bands (think lake effect type) that can drop moderate to heavy accumulations in one town while the next town over sees some flurries and maybe a coating. My point here is that uncertainty is quite high.

Graphic Showing How A Low Forms Off The Maine Coast With Strong West Winds. Credit: Me
Graphic Showing How A Low Forms Off The Maine Coast With Strong West Winds. Credit: Me

Another thing to watch out for with Norlun type events is the threat for a mesolow to develop. Mesolows are caused by rising air along and near the trough and also westerly winds accelerating and veering as they move from a high friction environment (over land) into a low friction environment (over water). Imagine the right front tire of your car running into a patch of ice. As that tire moves from a high friction environment (pavement) into a low friction environment (ice) it accelerates while the left front tire is stuck on the high friction pavement and can’t move as fast. The result is your car spinning out. The same thing happens with air moving from over land to over water. Above I’ve drawn up a quick graphic showing how west winds and a cold airmass emerging over water can generate a low. The divergence aloft and strong upper energy aids in this process. This doesn’t happen behind every cold front because often the air is and sinking. The air monday will be rising due to the approaching upper low/divergence which will help with the development of the low.

12Z CMC Showing The Potential For A Mesolow Along The Coast Monday Afternoon. Credit: Weatherbell
12Z CMC Showing The Potential For A Mesolow Along The Coast Monday Afternoon. Credit: Weatherbell

The 12Z CMC shows this potential well. Should this occur, most of the coast could see a moderate snowfall and amounts would be slightly less dependant on the fickle Norlun. While most models don’t show this, based on warm waters (still over 40 degrees!), rising air ahead of the upper low, the strong energy aloft, and the movement of the surface airmass, I think there is a good chance some sort of mesolow develops and strengthens tomorrow afternoon.

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Here are my thoughts for snow. This is tentative as Norlun troughs are notoriously fickle. I’ll have another update tomorrow morning.

-Jack