February 29 8 PM Update – As we close out Leap Year Day and look ahead to the first week of March, there are two things I need to address. Just so you don’t think I am a one trick pony, I know many of you need sunshine in your life. The upside of this new month is that is coincides with the first sunset of the year at 6 PM  in Baltimore. The longer daylight and new month brings spring to the forefront, but winter is not done yet.  We have two chances this week and if you have ready my recent updates, I have been trying to downplay them. Now it’s time to take this more seriously as the timing has changed. So the snow will take advantage of cold air in place, plus the earlier arrival overnight.

Before I get to the maps, here is the quick rundown this week:

  • Tuesday: Still a quiet and mild start to March “In like a lamb”
  • Tuesday Night: Rain
  • Wednesday Morning: May end as wet snow. Some chance of stickage well west and north of the Bay.
  • Thursday: Snow arrives around midnight
  • Friday morning: Moderate snow, stickage with road impact near and west of I-95. Temps below freezing west of the Chesapeake.
  • Friday: Lingering snow, but battling the higher sun angle. Wet roads likely.

Mid-Week Storm:

The GFS Model is the most aggressive with the snow Wednesday morning. But note the freezing line well north and west.

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*This storm is important for two reasons. First, it shows the GFS trend pushing systems south of the original track. That is a colder trend.  It could give us insight in the behavior of snow on warmer ground as it pulls away. Second, this storm will help reinforce the cold core of the jet stream in eastern Canada. That will send colder air southward into Pennsylvania and Maryland. It will also act as a block for the next developing system.  Here is a look at the jet stream Friday morning. The contrast of this cold air in New England and the warming trend in Texas will help generate some spin… or this new Low Pressure heading our way.  It didn’t look like much when I first showed this over the weekend. But the cyclogenesis is pretty evident now and it will help generate its own cold air. The will be marginal, but just cold enough for the flakes.

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Now let’s get to the main event:

It is important to note that in March, the best chance for stickage and accumulation is at night. When snow falls during the day, it must compete with a higher sun angle. The result can be wet roads with accumulation on the grass. Then elevation comes into play with slight change in temperature making all the difference.

GFS Model

This has been showing the trend of a colder, stronger system… in part because it is faster. This allows it to act on the cold air in place, which would be moving out if this was 12 to 18 hours later.  So when I first mentioned the arrive during the day Friday, that was the case. Here it looks like the onset will be close to midnight Thursday into Friday morning. When contrasting all the models, this is the middle of the road. So at this point the safe solution.

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The Canadian GEM Model

While I like this model in winter with arctic dominate patterns, this is the outlier. But it is consistent with snow Thursday night into Friday morning.  This shows moderate snow lasting into Friday afternoon. This still shows the strongest system, with a coastal development to a blizzard for New England. Contrast that with the European Model that still has this too far south for an impact on our region.

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How Much Snow?

I will not entertain that. Besides my philosophy of waiting until within 48 hours of the event, there are too many other factors. Yes, I see snow for us on Friday morning. The timing of earlier arrival makes this more of a potential road impact that I earlier thought. But we still have to consider the warm ground and the huh sun angle. The snow can last through Friday, but that does not mean all of it will add up.  So I need to analyze the timing and intensity and then shave off the daylight snowfall from potential totals.  That will be my approach with a first call Wednesday.

Like I said, there was still winter left and we have this to talk about all week.

Faith in the Flakes

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