Next Chance of Accumulating Snow: Saturday Night - Sunday
Probability of Accumulating Snow (1" or more): 20%
Winter just does not want to go away! Over the past couple of days, some weather organizations have tried to advertise this storm as more than what it is. We're in Mid-March, accumulating snow gets really difficult. Unless the snow is falling at night, or it's falling hard during the day, the snow really has no chance at actually accumulating, even though it may be falling from the sky.
Right now, it appears that we have an initial wave of precip that moves in around lunchtime on Saturday. For most of the region this will be all rain as temps get between 39-43. The only exception to that would be the high tops out in the mountains that may mix with some snow. Once the sunsets on Saturday, areas northwest of DC should transition over to snow, with that rain/snow line closing in on I-95. This is when those areas should get most of their accumulation, as SoMD stays all rain with temps remaining in the middle to upper 30s. On Sunday, areas northwest of I-95 should continue to see snow, but once the sunrises, not much more will accumulate other than what did so already. Later in the day on Sunday, mainly after 4pm, is when some of you in northern Calvert and Charles counties may start to mix with snow. Once the sunsets on Sunday, the storm will be pulling away from our area, but this would be our best shot in SoMD of seeing any snow. I think we at least have the chance to mix with some snowflakes before midnight, but very little (if any) will accumulate on the grassy surfaces. Below is a slideshow of how all of this should play out.
Impacts from this storm will be rather minimal. This weekend will be wet and raw. Temps never get above 43 and most of the weekend will be spent either with precip falling from the sky, or with a mostly cloudy sky. Any outdoor activities will likely be rained out, but expect only wet roadways both days. Expect no impacts for Monday.
The Bottom Line is that this storm is going to be mainly a rain event here in Southern Maryland. Any snow that falls will do so Sunday around dinnertime, but even that probably won't accumulate. The past few events have over performed for SoMD, but I really don't see that happening this time. If anything, I could see this system being warmer than my current forecast. Nevertheless, I anticipate this being my only forecast for this storm. If something drastically changes overnight, I will update my forecast in the morning. Stay with JB Weather for continuing coverage throughout the weekend.
We are now within 12 hours of this time period of wintry weather starting, and we have a much better idea of what will happen than we did yesterday. However, there are a few things we do not know, and that we probably won't know until the event starts. Nevertheless, I think after this storm, we will be done with winter.
What we do know is that a weak area of low pressure, referred to as a clipper, is currently moving out of the Midwest and into the lower Ohio River Valley and Mid-Atlantic. As it moves closer towards the Mid-Atlantic, and surge of moisture will overspread the area around 5pm (give or take a hour or two). This initial surge of moisture should be all rain. If temps can drop quick enough, that surge of moisture may be able to end as some snowflakes around 10pm or so, but don't bet on it. It's during this time that areas north and west of DC should see most, if not all, of their accumulations. There will then likely be a little bit of a lull once that round of precip ends around midnight.
As that weak area of low pressure, moving out of the Midwest, dies off, a coastal storm (which is already developing), will take over. That coastal storm will move northward throughout the night, and bring in our next surge of precip into the area, which should be mostly snow.
What we don't know mainly concerns the coastal system. The biggest question is, "How far north and west does it track?" The further northwest it is, the more snow we could see. Right now, it appears that the coastal storm should stay far enough to our southeast to spare us of a significant snowfall, but it should come close enough to give us some snow.
Another worry I have concerns the temperatures during this event. Temps will only be marginally cold enough for snow (31-34). However, if the storm can come far enough northwest, we will see heavier precip, which would overcome the temps and cool our atmosphere. Temperatures will also determine what sticks. We'll need temps to be closer to 32, or below, to really pile anything up. Roads should be fine. Our snow totals will be dependent on how low the temps get and how heavy the precip is (which is dictated by how far NW the coastal storm can come).
Currently, we have a Winter Weather ADVISORY up for a large chunk of the Mid-Atlantic for the possibility of at least 2" of snow. Again, the totals NW of DC are dependent on the first round of moisture, and I'm not sure that will have enough of a punch with that to bring more than an inch or maybe two to most locations. I think that most areas southeast of DC should be able to meet the advisory criteria of 2" with the coastal storm.
Impacts across Southern Maryland should be minimal to moderate. Right now, I do expect delays and a few closings for area school districts (refer to the School Odds below). Expect a few slick spots on the way to work tomorrow morning as well. For federal and military employees, I don't think you will get a delay (I'd place it a 30% chance), but I could see Liberal Leave/Telework being an option that is offered.
If this coastal storm tracks further south and east, and we don't see the snows we're expecting, everyone should go to school on time, and there would be no issues with the AM commute. If the storm comes a little further north and west than expected, then the chances of closings and delays goes up along with impacts in the morning. Remember, this time of year, it is hard to accumulate snow on the roads. With this storm, it's more so the timing, than the amount.
The Bottom Line is that snow looks likely tomorrow morning. An initial area of precip will move through tonight giving the NW DC suburbs their snow, while we should get rain. A coastal storm will then head northward, before going out to sea, which should give us our accumulating snow in the morning. Remember, this time of year, it is hard to accumulate snow during the daylight hours. We could see more snow if this coastal storm moves further NW than thought (25% chance) and we could see less if it stays further to our SE (20% chance). If my forecast verifies, as I think it will, there will be a few issues tomorrow morning with some slicks spots. However, because of the timing we could see area schools opt to delay or cancel classes. Temps warm to near 40 in the afternoon, so any snow should be gone by then! Stay with JB Weather for continuing coverage.
Next Chance of Accumulating Snow: Thursday Night - Friday Morning
Probability of Accumulating Snow (1" or more): 50%
It looks Winter is finally coming to an end for Southern Maryland. I think this week will be our last real shot of cold air as well as our last winter weather threat. However, before we leap into Spring, there is, what appears to be, our last winter weather threat for late this week. Just 36 hours out, there is a bit of uncertainty with this forecast.
What we do know is that we will be dealing with two systems. There will be an initial weak area of low pressure, referred to as a clipper, that will track from the Mid-West into the Ohio River Valley, Thursday into Thursday evening. As that weak storm moves into the Ohio River Valley, a surge of moisture will overspread the area after rush hour, and that should be mainly rain. However, it looks like that surge of moisture may be able to end as a period of snow. That "clipper" will die off, and a new area of low pressure will develop along the coast early Friday morning
What we don't know is how that second area of low pressure, that will develop along the coast, will track. Initially, it had appeared that the coastal storm would stay far enough out to sea, which would mean that any snow accumulation would come from the weak clipper. However, recent weather guidance has brought that coastal storm a bit closer to the coast, which would be mean the chance of higher totals. Below, I have drawn the area that I think has the highest chance to exceed my forecasted amounts. What are the chances that our area sees more snow? I'd give it a 50/50 shot. I will have a better idea on this possibility by tomorrow, but the latest trends have been for more snow.
Impacts for our region will not be high, but will be very dependent on how much we see. If that coastal storm takes a path closer to the coast, we would likely have a few delays and closings, and travel would be difficult Friday morning as the peak of the snow would be 3am - 9am. However, if the coastal storm stays further out to sea, impacts would be very minimal as we would only see up to 1" on grassy areas. Right now, my forecast takes into account the "clipper" and some snow from the coastal storm.
The Bottom Line is to expect at least a little bit of winter weather late Thursday night into Friday morning. Rain should overspread the area after Thursday's evening rush hour, and should change to snow as the weak area of low pressure dies off. A developing coastal storm may come close enough to brush us with some more snow Friday morning. There is some disagreement with how close this system gets. The closer to us this gets, higher the snow totals. Expect some impacts Friday morning, but I'm not sure how many delays and closings there will be. It's hard to accumulate snow this time of year. I will have a much better idea of how things should play out tomorrow, so stay tuned!