Tag Archives: Maine

Inland Runner To Bring A Mix Of Precip Tonight Through Thursday

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Hello everyone!

Another storm is tracking up the Ohio River Valley this week and it will bring with it a mix of snow, sleet, freezing rain, and rain with the chance for a rumble or two of thunder. This storm is really two storms, one moving offshore tomorrow and another moving to our west Thursday. The first storm has the frozen precip while the second storm has the liquid precip. I’ll break down each and every impact below starting with some snow tonight into early tomorrow morning.

First Storm: Snow

5:00PM Observations Showing The Setup Tonight/Tomorrow Morning. Image Credit: COD
5:00PM Observations Showing The Setup Tonight/Tomorrow Morning. Image Credit: COD

Low pressure is moving NE offshore this evening and will bring us a round of precip tonight into tomorrow morning. Due to a cold dry airmass out ahead of the storm, this precip will start out as snow tonight with a couple inches of accumulation. Warm air will  be blasting in aloft and will change snow over to sleet and freezing rain for the AM commute tomorrow. Before the changeover, a few inches of snow are expected but accumulations should remain fairly light. The snow combined with the icy mix will make for a very slick AM commute so be sure to allow extra time for slow travel tomorrow morning.

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Here is what I expect for snowfall accumulations. The immediate coast could go over to rain fairly quickly so little accumulation is expected there. Most areas see 1-3″ but areas in the far north are likely looking at a good 3-6″ before warm air aloft finally gets up there mid day tomorrow.

First Storm: Ice

18Z NAM Sounding Showing Freezing Rain Potential Tomorrow Morning. Image Credit; Twisterdata.com
18Z NAM Sounding Showing Freezing Rain Potential Tomorrow Morning. Image Credit; Twisterdata.com

Warm air aloft will easily move in tomorrow morning. At the surface however, the cold will put up a solid fight. As a result, freezing rain is expected to be widespread tomorrow. This vertical profile of the atmosphere tomorrow afternoon near Rumford shows what I’m talking about. Snow will form and fall in the upper levels of the atmosphere which are below freezing (upper blue area). They will then fall into an above freezing layer which will feature temps near 5C (41F) and the snow will melt. Just before it falls to the surface, it will encounter more below freezing air. This won’t be cold enough for long enough to refreeze the rain back into sleet but it will be cold enough to allow the rain to freeze on whatever it hits. This is how we get freezing rain. As long as the lowest levels of the atmosphere stay below 32F, ice will continue to pile up. The greatest risk for solid ice accumulation is in the mountains and foothills where cold remains in place the longest. Closer to the coast, the very bottom of the atmosphere will warm faster but a sliver of below freezing air will remain between 500 and 1500 feet in elevation. If you live between those elevations anywhere in Maine, you are at risk for a fairly significant ice event.

2-23 Graphic 6

Here are my thoughts on ice accumulation. Keep in mind, areas between 500 and 1500 feet in elevation run the risk of up to .5″ of ice even towards the coast. At lower elevations near the coast, less ice is expected and the immediate shorelines will likely escape the ice for the most part as temps quickly rise to above 32F. Also keep in mind that a half inch (.5″) of ice is enough to cause tree damage so power outages are definitely possible during this time in any areas that do get close to that half inch mark.

Second Storm: Rain

12Z Hi-Res NAM Showing Heavy Rain Thursday Morning. Image Credit: Weatherbell
12Z Hi-Res NAM Showing Heavy Rain Thursday Morning. Image Credit: Weatherbell

Strong southerly winds eventually get rid of any remaining holdouts of cold air. This will occur from SE to NW Wednesday evening into Wednesday night and the job won’t be completely done for the mountain valleys until the wee hours of the morning Thursday just before the heavy precip moves in. When the heavy stuff does move in, temps will be above freezing for all. While the frozen precip risk will be diminished at this point, we do still have two threats: rain and wind. Between 1 and 2″ of rain is expected for everyone across the area and this combined with warm temps could result in some minor drainage flooding. More impactful river flooding is unlikely though we do run the risk of ice jams on the bigger rivers which very well could cause problems. High winds will be possible with a line of heavy showers Thursday morning and a rumble of thunder cannot be ruled out. Heavy rain clears Thursday afternoon with just residual showers through Thursday evening. Gusty westerly winds will bring temps back below freezing Thursday night and an inch or two of upslope snow is likely during this time as well.

Second Storm: Wind

18Z NAM Showing A Strong But Not Ridiculous Low Level Jet Thursday Morning. Image Credit: Weatherbell
18Z NAM Showing A Strong But Not Ridiculous Low Level Jet Thursday Morning. Image Credit: Weatherbell

A band of strong winds aloft will be moving through at the same time the heavy rain will be and thus we run the risk of some of those winds being mixed down to the surface. While these winds could be strong, notice the lack of bright pink/purple we saw last week indicating these winds will be weaker. While I don’t expect any major issues with these winds, I am worried about scattered power outages especially in areas where ice from tomorrow has weakened trees. In terms of how strong I expect the winds to be, coastal areas could see gusts to 50 mph while the rest of the area sees gusts to 40 mph. Winds turn westerly Thursday afternoon and remain gusty but calm down into the 20-30 mph range which should limit any impacts after noon ish Thursday.

To recap, snow moves in tonight followed by ice tomorrow morning. Ice slowly changes to rain from SE to NW Wednesday night with everyone seeing rain by the time heavy precip arrives Thursday morning. Heavy rain will mix down some high winds Thursday morning causing scattered power outages especially in areas where ice on Wednesday has weakened trees. Rain and wind clears out Thursday afternoon as westerly winds bring in cooler and drier air. Upsloping will keep precip up and running in the mountains where an inch or two of snow is likely into Friday morning.

A cold front passes through Saturday night followed by a warm front Monday. Another cold front arrives Tuesday followed by colder temps.

Another update tomorrow morning.

-Jack

Another Inland Cutter This Week

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Hello everyone!

The forecast for Wednesday into Thursday remains on track this evening. As it is drawing nearer, I’ll elaborate a little on the expected impacts which include snow, sleet, freezing rain/ice, heavy rain, and wind. I’ll do a quick rundown of each threat. All in all, this will be a fairly typical inland runner and nothing out of the ordinary is expected for Maine. One wave of precip will arrive during the day Wednesday into Wednesday night while the second will arrive Thursday morning and continue through Thursday afternoon. A third wave is likely following that which will last into early Friday morning.

Wave One: Snow

12Z GFS Showing The Setup For Snow Wednesday Morning. Image Credit: Accuweather
12Z GFS Showing The Setup For Snow Wednesday Morning. Image Credit: Accuweather

Ahead of the storm, we have fairly cold air (step outside if you don’t believe me). As per usual, cold air leaves when it pleases and as warm air begins to move north, the first phase of the fight will feature snow Wednesday morning. A general 1-3″ is expected before warm air aloft moves in to turn things over to sleet and freezing rain. A bit more is expected in the mountains where I could see 2-4″. I also wouldn’t be surprised if coastal areas only saw a coating. This will fall overnight tomorrow into the early morning hours Wednesday. As dawn breaks Wednesday, warm air aloft will be gradually changing things over to sleet and freezing rain from south to north.

Wave One: Mix

12Z GFS Showing The Cold Air Damming Setup At The Surface Wednesday Night. Image Credit: Accuweather
12Z GFS Showing The Cold Air Damming Setup At The Surface Wednesday Night. Image Credit: Accuweather

While warm air will stream in unopposed aloft, the cold will put up a good fight at the surface. High pressure will be slowly sliding east across the Canadian Maritimes and I expect low level cold to hang on for a good long time. The map at left shows winds at the surface Wednesday evening. Notice NE winds still locking in cold air at the surface Wednesday night. The development of weak low pressure offshore will aid in this process. This wind will continue to cause problems even into the beginning of wave two which arrives Thursday morning just as this is beginning to erode. Several tenths of an inch of ice are possible and could lead to power outages especially if it doesn’t get a change to melt before the high winds associated with the cold front arrives.

Wave Two: Rain

12Z GFS Showing Heavy Rain Moving In Thursday. Image Credit: Weatherbell
12Z GFS Showing Heavy Rain Moving In Thursday. Image Credit: Weatherbell

Eventually, the cold air will be swept out of the way as SE winds pick up. A cold front will be approaching and ahead of it will be a line of heavy showers with some embedded thunder possible. A general inch to two inches of rain is likely which could lead to minor drainage/urban flooding. Despite that, no major issues are expected as we hardly have any snowpack to melt away.

Wave Two: Wind

12Z GFS Showing High Winds Once Again Lurking Above The Surface. Image Credit: Accuweather
12Z GFS Showing High Winds Once Again Lurking Above The Surface. Image Credit: Accuweather

As is usually the case with these storms, a band of strong winds will cross the area around the time of the heavy rain. The heavy rain will help mix some of those winds to the surface which could lead to scattered power outages. Notice the lack of bright pinks and purples in this map where we had them covering the entire region last week. Winds this week will be slightly weaker with 40-50 mph gusts most likely (last week we had 50-60 mph winds).

Wave Three: Light Mountain Rain/Snow

12Z GFS Showing Light Rain And Snow Moving Back In Friday Morning As Cold Air Pours Back In. Image Credit: Weatherbell
12Z GFS Showing Light Rain And Snow Moving Back In Friday Morning As Cold Air Pours Back In. Image Credit: Weatherbell

As cold air pours back into the area Thursday evening, an upper disturbance will pass overhead which will cause another batch of precip to move through. This will be most widespread in the mountains but everyone has a shot at a quick coating-2″ of snow as westerly winds bring the cold back in. This should move in late in the evening Thursday and should be out of here by dawn Friday.

More updates in the coming days.

-Jack

Rain Expected This Week As Another Strong Storm Lifts West

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Hello everyone!

Yet another storm has decided to cut west this week as our pattern continues to disappoint for skiers and other winter enthusiasts. This storm will be a lot like our last storm and will, as with most inland runners, feature front end frozen precip, heavy rain, and high winds. Precip moves in Wednesday afternoon and moves out Thursday evening.

12Z GFS Showing The Setup With The First Wave Wednesday Evening. Image Credit: Weatherbell
12Z GFS Showing The Setup With The First Wave Wednesday Evening. Image Credit: Weatherbell

The storm will, as these storms usually do, take place in two stages. The first stage will be Wednesday afternoon into Wednesday evening with light snow changing to ice and rain. During this time, the warm front will be lifting north and cold high pressure will still rule with some weak Cold Air Damming in the mix as well. Accumulations will be on the light side, probably remaining under 3″ of snow though exact amounts are still yet to be determined.

12Z GFS Showing The Setup For The Second Phase Of The Event Thursday Afternoon/Evening
12Z GFS Showing The Setup For The Second Wave Thursday Afternoon/Evening. Image Credit: Weatherbell

A lull will occur Thursday morning as the warm front passes north. Winds will become strong out of the S/SE which will blast out any of the last cold pockets. Heavy rain associated with the cold front will approach and move into the area Thursday afternoon/evening and will bring with it the standard high wind/heavy rain threats with localized flooding and power outages possible. Exact winds are still to be determined but will likely be just a click below those of our last event which would indicate gusts to or around 50 mph along the coast with lighter winds inland.

Colder air moves in for next weekend along with another shot of snow currently centered around Saturday.

-Jack

Next Week Looks Stormy, Details Remain Uncertain

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Hello everyone!

Our storm this upcoming week is still on track but just because we’re getting closer to the event doesn’t mean we’re all that much closer to deciphering what will happen. The trend in guidance over the past 24 hours has been towards a warmer solution with brief snow quickly going over to rain. While this remains very much a viable solution, I’m not ready to bite just yet. I want to wait for a few more rounds of guidance with better sampling of the disturbances that will eventually form the storm before I pull the trigger on a rainy solution. Due to that, my thoughts haven’t changed much. A cold front will move through tomorrow night and colder air will follow for Monday. Low pressure will then move NE from the Gulf of Mexico. Its exact track will determine what falls from the sky. We should have a better idea Monday afternoon as the disturbances that will form the storm begin to join together over Texas.

12Z GEFS Showing Uncertainty In The Forecast For Next Week. Image Credit; Weatherbell
12Z GEFS Showing Uncertainty In The Forecast For Next Week. Image Credit; Weatherbell

Here are the GFS ensembles for the storm. While there is still a large spread in ideas as to where the storm will track, guidance is converging on an inland track. Notice the lack of a large high to the NE to feed cold air into the region. Our cold high from Monday has already been swept off to the Azores which leaves warm air free to flood northward. While I’m still not completely convinced, this is the solution I’m leaning towards based on the pattern and what I’m seeing in terms of guidance.

Following this storm, colder air moves in for the weekend and we have another shot at snow around that time as well.

-Jack

A Progressively More Active Week

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Hello everyone!

Our pattern slowly becomes more active over the coming week beginning with light snow tonight and ending with what could be a large storm next week. We still have three storm threats but I don’t think Northern New England gets much of anything with the Monday storm threat I talked about a couple of nights ago. However, that storm still plays an important part in the lead up to what has the potential to be a large storm next week. For now, let’s look at tonight and the storm expected to drop light snow in the next 12-18 hours.

Radar/Surface Obs Composite From ~5:00PM This Evening. Image Credit: COD
Radar/Surface Obs Composite From ~5:00PM This Evening. Image Credit: COD

Light precip is falling over NY currently and this will move east into our area tonight. The low pressure responsible is tracking to the north and thus is dragging warm air up into the region on southerly winds. This will be enough to result in a wet snow for the mountains and foothills and wet snow mixing with rain along the coast. Snow will fall predominantly tonight into tomorrow morning and will be largely in the form of snow showers with on and off precip. Little accumulation is expected and my original thinking of 2-4″ for the mountains, 1-3″ for the foothills, and a coating-2″ for the coast/coastal plain looks good. Warmer air will flood into the region behind this storm on westerly winds setting up spring like temps this weekend. Highs tomorrow will be in the 30’s and 40’s following precip clearing out in the morning. Highs Sunday will get close to 50 in the south with 40’s for most.

18Z NAM Showing The Setup Monday As Cold Air Builds. Image Credit: Accuweather
18Z NAM Showing The Setup Monday As Cold Air Builds. Image Credit: Accuweather

A cold front sweeps the warmth offshore Sunday night and low pressure develops along the front Monday. This will remain largely to our south though more clouds are likely for all with a flurry possible in the south. The big impact though will be the cold building in with a fresh Canadian airmass sweeping SE. By the time Tuesday rolls around, we will have a stalwart 1030mb+ high that won’t be in a hurry to move. This sets up our midweek storm threat.

12Z GFS Showing The Complex Storm Threat Midweek. Image Credit: Accuweather
12Z GFS Showing The Complex Storm Threat Midweek. Image Credit: Accuweather

By the time next week arrives, a large and fairly deep trough will be carved out across the east with a ridge in the west. Tons of disturbances will be zooming around the east and the exact track of the storm(s) will depend on the exact strength/placement of each and every one of the disturbances I circled in blue (along with others not visible in this image). This is why this forecast is so darn complicated. Despite that, I think we can begin to make some sort of sense out of at least the basics. It is far too early to talk precip type or exact timing but I think the storm works in two parts. The first arrives at some point Tuesday or Wednesday and remains moderate or weak in strength. It looks to deliver moderate to light precip of some sort depending on the track. Remember, we have fresh cold in place so my inclination would be to lean towards less, colder precip as the low slides south. The second part of the storm arrives later in the week, Wednesday into Thursday and is much stronger.  It could deliver much more precip depending on the track. Of what nature the precip is and exactly when it comes and goes is anyone’s guess at this point but the takeaway is that it could be much stronger.

All in all, a more active pattern is shaping up for our area heading into next week. While the exact details are TBD, it does look like we have a good chance at seeing significant precip. Could it be mainly rain? Sure. Could it go out to sea? Possibly. Could it deliver significant frozen precip? Absolutely it could. Stay informed with the latest forecasts through your favorite source (NWS, local media, people like me) and remember that this is still very far away. Don’t panic, stay informed.

-Jack

A Messy Storm Tonight Into Tomorrow

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Hello everyone!

Snow is moving into Southern New England this evening ahead of our next storm and snow will move NE into our area tonight. Snow mixes with and changes to freezing rain tomorrow morning before a lull tomorrow afternoon. The lull ends with heavy rain and wind Tuesday evening before we clear out and cool down Wednesday morning.

First Round: Frozen Medly

Evening Radar Showing The Setup For Tomorrow. Image Credit: Accuweather
Evening Radar Showing The Setup For Tomorrow. Image Credit: Accuweather

The general idea from Yesterday remains the same but with a few tweaks. Snow will move in from SW to NE this evening beginning around 7 in York County. Radar is indicating snow is falling across York County however with VERY dry air at the surface, I doubt this is making it to the ground. The ground is very cold and thus snow will accumulate quickly and efficiently once it starts falling.

2-15 graphic 2

Snow will fall throughout the night tonight and will accumulate to 1-3″ before warm air aloft begins to change snow to ice around or a little after midnight. Along the coast and across the coastal plain, this is all the snow you’ll get. For inland areas, another inch or two is likely bringing total snow to 2-4″. The mountains hold on to snow the longest with 3-6″ of accumulation. While the mid levels of the atmosphere get torched by a 50kt+ Low Level Jet, the air right near the surface will remain cold as cold dense air settles to the surface. For this reason, expect freezing rain to be the dominant precip type tomorrow morning with some sleet mixed in towards route 2. This will lead to a VERY slippery morning commute with roads a total mess due to several inches of snow under some sleet under a layer of freezing rain.

Second Round: Tropical Punch

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18Z NAM Showing Very Strong Winds Aloft Tomorrow Evening. Image Credit: Accuweather

Freezing rain will continue through mid to late morning tomorrow before tapering to freezing rain showers as a dry slot briefly works in. During this time, the cold air will gradually be mixed out as southerly winds kick in. Precip will resume tomorrow evening as a cold front approaches. This round will be mainly rain except maybe for some isolated mountain valleys. Rain will be heavy at times and thunder is not out of the question as the cold front moves through. Winds will be gusty at this time as well with gusts over 40mph possible. Winds will be limited however by how much the cold air hangs on. The longer the cold hangs in, the more wind we see. Some power outages are possible during this time though significant impacts seem unlikely.

Rain moves out late tomorrow night with clearing and cooling expected Wednesday. More snow/rain is possible for Friday as a clipper system moves over the area.

-Jack

A Mess Of A Storm Tuesday

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Hello everyone!

Low pressure will pass through the area in waves tomorrow night through Wednesday. The track of the main low will be to our west so this will be a snow to mix to rain event even in the mountains. Snow, freezing rain/ice, flooding, and wind threats with this storm. I’ll outline each below broken down by wave. The first wave is the cold phase of the storm with snow and mix while the second wave is almost all rain. There is a chance we see a third wave on Wednesday with more snow but that is far from certain. Let’s dig into the forecast.

The Setup

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12Z RGEM Outlining The Major Players In Tuesday’s Storm. Image Credit: Weatherbell

Here is the RGEM model for Tuesday morning showing the major players. A storm is moving across the southern Ohio valley right now and will move into VA tonight. It will then move NE along a warm front and that will deliver our first shot of precip. Given how darn cold the air is out ahead of this storm, I am hesitant to jump at warm air blasting in without a fight. That being said, SW winds will have all of Monday to moderate the air before the storm even arrives. Also, the high pressure system containing the cold air will be retreating offshore which means it won’t be funneling cold air into the area through the event. Instead, counterclockwise winds around the high to our east will help promote strong southerly winds which will greatly help warm air coming north.

First Wave: Cold Air Hangs On

12Z HRDPS Showing How Cold Air Could Hang Tough Tuesday Morning. Image Credit: Weatherbell
12Z HRDPS Showing How Cold Air Could Hang Tough Tuesday Morning. Image Credit: Weatherbell

The first wave of precip will arrive tomorrow night and will initially be in the form of snow. Several inches will accumulate by Tuesday morning and this will cause the Tuesday morning commute to be messy. Use extra caution and allow for extra time to get to work/school. The mesoscale higher resolution models such as the RGEM and HRDPS are holding the cold air in place much longer than the lower resolution global models. This is a good indication that cold air will hang on unusually long, as it almost always does in Maine in February after an Arctic blast with a solid snowpack on the ground. For those reasons, I am hesitant to believe fully that anyone but the immediate coast changes to rain before midday Tuesday. My time forecasting here has taught me never to underestimate the sticking power of Arctic air.

First Wave: Freezing Rain Threat

12Z GEM Showing Freezing Rain Potential Tuesday. Image Credit: Weatherbell
12Z GEM Showing Freezing Rain Potential Tuesday. Image Credit: Weatherbell

As the first wave moves through Tuesday, winds aloft will be blasting the area with a blowtorch, sending warm temps deep into the area. Cold air aloft is easy to displace. However, cold air at the surface doesn’t like to go anywhere in a hurry. The 12Z GEM shows this well. Tomorrow morning, the surface freezing line will hug the surface warm front offshore. The low level cold will dam along the mountains and will generally be sluggish in terms of going anywhere. In between the freezing line aloft and the freezing line at the surface, there is the risk for freezing rain. For the foothills, this could be a respectable freezing rain event with amounts of a tenth to as much as a third of an inch possible. Depending on exactly how much warm air moves in aloft and exactly where in the atmosphere it does, sleet is also possible. The mountains will remain cold enough for snow for most of this time as the upper level warmth won’t quite make it there in time for the first wave. The coast will likely see the surface warm front move just far enough inland to bring temps above freezing leading to rain.

First Wave: Accumulations

Snow map 2-14

Here’s what I’m thinking for accumulations for the first wave from tomorrow night through Tuesday evening. After Tuesday evening, everyone most likely changes over to rain as warm air streams in. This could be a significant enough icing event for the foothills to lead to scattered power outages especially if the inversion can break enough to allow for gusty winds with the second wave Tuesday night. Most of this is washed away Tuesday night with the rain but it will be quite slippery for both the AM and PM commutes Tuesday the more so the farther inland you go.

Second Wave: Cold Air Washed Out

12Z GFS Showing Strong Winds Just Above The Surface Pumping Warm Air Into The Area. Image Credit; Accuweather
12Z GFS Showing Strong Winds Just Above The Surface Pumping Warm Air Into The Area. Image Credit; Accuweather

After the first wave departs early Tuesday afternoon, we will see a lull in the action before the main storm passes well west of the area. The initial wave will help lift the warm front north of the region and warm air will begin to stream into the entire area. By the time round two arrives Tuesday evening, almost everyone will be warm enough for rain. Winds will become quite strong out of the south and south east aloft and there is the risk that some of those gusts mix to the surface in some capacity though a strong inversion will keep the serious winds mainly to our south. Especially along the coast though there is the risk for gusts up to 35mph. The warmer your temperature, the higher your risk for winds which is why the coast is at the greatest risk for wind. The mountains and especially the mountain valleys do an exceptionally good job holding on to cold air and I wouldn’t be surprised to see some mountain spots hold on to some variety of frozen precip throughout the whole event. The farther north and west you go the more likely this is. A general .5 to 1″ of rain is expected with this event which could lead to isolated flooding with frozen ground and a little snowpack.

Third Wave: Surprise Snow Wednesday?

12Z GFS Showing A 500mb Setup That Is Dangerous For Surprise Snow Wednesday. Image Credit: Accuweather
12Z GFS Showing A 500mb Setup That Is Dangerous For Surprise Snow Wednesday. Image Credit: Accuweather

The rain moves out quickly Tuesday night and cold air moves back in for Wednesday. Another storm is right on the heels of this one but right now the thinking is it stays south. However, the 500mb setup pictured is dangerous for surprise snow with a long nose of energy pointed right at us. Most likely a storm forms and models are currently thinking it heads well south but I’m not fully convinced yet. Even without a robust surface storm, trouble could still be caused by upper level energy. It is also possible enough dry air moves in behind the rain that we don’t get anything. We’ll have more clarity on this once we figure Tuesday out which might just be on Tuesday.

A period of cool calm weather arrives Thursday into Friday and another storm threatens for Saturday with a mix of snow and rain likely.

-Jack

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