00:00Well, we have a couple of rounds of wintry weather this week here.
00:04Christmas is going to be kind of sandwiched between rounds of this activity.
00:09We even have a sneaky little bit of a freezing rain producer possible for some parts of maybe western Maryland,
00:16south central Pennsylvania on at least Christmas Eve night into early Christmas morning.
00:21That could expand north a little bit.
00:24We'll look at that, but there's a bigger storm lurking that will be a greater impact,
00:28a bigger storm for Friday evening, so Boxing Day.
00:32Let's get into the details here.
00:34I'm going to first begin with some models.
00:36And overall, there's a sneaky little system.
00:38I don't want to spend much time on this, but this little dip in the jet stream, just a little bit of a trough.
00:45You can see a little kink to the lines there, the thickness and height lines.
00:49And there's a little bit of vorticity with that.
00:50That's Christmas Eve night into Christmas morning.
00:53Take a look at what this produces.
00:54Not much, but just a little hint of some rain and a little bit of freezing rain for some Christmas Eve night into Christmas morning.
01:04It's not going to be a big storm, but I don't want you to miss that.
01:07Sometimes these sneaky little systems that don't make many headlines can cause trouble on the roads.
01:12That was the GFS depiction of things where mostly snow from areas maybe from Gettysburg,
01:18mainly a little bit of freezing rain, I should say, from near Gettysburg up to the north and rain to the southwest.
01:22It would be a little bit of freezing rain.
01:25The European model, it mainly keeps the precip so far southwest that it buries it to the point that it's mainly just rain with very little or no ice.
01:34And then a third opinion, the Canadian.
01:36Here, this is just kind of splitting the difference.
01:38A little more precip north up into the colder side, up near Messina, New York,
01:43and near the Canadian border north of the Adirondacks, with hints of a little bit of freezing rain for some.
01:48And I suspect it could sneak a little farther south.
01:52The models are often a little shy on holding on to the cold appropriately there into areas like the Shenandoah Valley.
01:59And the Ridge and Valley region tends to run a little colder than models often anticipate.
02:04So that's just something to keep in mind.
02:05That's not the main event.
02:07The main event follows that.
02:09And it's going to scoot across the upper Midwest.
02:11And it's this system.
02:13It's not going to be a blockbuster east coast storm, but there's enough lift in the atmosphere.
02:20Here's a trough.
02:21And you can see that zone of extra vorticity spin in the atmosphere.
02:26That's going to pretty aggressively push across the Great Lakes.
02:29And part of the problem is there's fresh, cold air for this to interact with.
02:33Here's a different depiction of it, the European model.
02:36And it's similar.
02:37You can see clearly, in this case, actually, it's a negatively tilted trough.
02:42It's a little more negative than the other one, which would actually be a slightly stronger shortwave,
02:46even though it's not a very high amplitude system.
02:48It's shallow, but it is going to be interacting with some cold air.
02:53And you can see this beefy ridge of high pressure, 1029 high, centered over eastern Canada.
03:01Actually, where I paused it there, you can briefly see the plot of high pressure, 1036 high.
03:07That's a relatively strong zone of high pressure.
03:09So just for argument's sake, I'm going to put it a little off the map.
03:12But that's going to be a driver of delivering some fresh, cold air in place.
03:18And that's going to be setting the table for trouble here.
03:21And again, another depiction of that zone, 1034 high.
03:25That's a relatively strong high pressure system there in the European.
03:29And the European centers it a little farther south.
03:32Regardless, it would be, again, a driver in keeping fresh, cold air.
03:37And then the Canadian third stop here along the way.
03:40It's centered a little farther north, just off the map.
03:43But the same difference there with fresh, cold air being supplied by that.
03:47Take a look at the precipitation that begins to break out here as this rolls in.
03:50Now, the GFS model brings some robust sleet.
03:55Lots and lots of sleet on Friday afternoon and evening.
03:59Friday around 7 p.m., just beginning there in areas like New York City and Points East.
04:05Here's a different depiction.
04:06European, pretty good agreement.
04:07A lot of sleet, like a sleet storm here for some.
04:10And freezing rain potential for many in the pink zone.
04:14And then the Canadian model similarly brings us a lot of sleet and freezing rain.
04:19So sleet in this shade of peach, if you want to call it that.
04:23And then some freezing rain a little farther south with snow to the north.
04:26And take a look at how this evolves.
04:28Widespread, pretty heavy snow there for some in New York City and Points North.
04:32And this is going to be a high-impact event Saturday morning, tapering off.
04:36And then some lingering light snow to the north.
04:38Now, take a look at the difference.
04:40There is some clumsiness in the way computer models handle sleet sometimes.
04:45If you look at this, this is labeled as snow.
04:47So, we're not going to see, we're not going to see 9 inches of snow in Baltimore and 7 inches.
04:53I'll show you why in a moment.
04:55The European has a much better handle on how to handle sleet.
04:59The European model forecast of snowfall, it looks pretty good.
05:03I think this aligns pretty well with our forecast and with our thinking.
05:06The reason we're so confident.
05:08Look at the difference.
05:08If you just take some other weather apps out there that just take computer model data and post-process it with a nice-looking icon and say,
05:17here's your forecast, it's a disservice.
05:19You're going to get a forecast that produces 7 or 8 inches of snow near the Pennsylvania-Maryland line.
05:24It's not going to happen.
05:25This is much more accurate.
05:26And here is why.
05:27If we look aloft, this is the same model that brought us that 7, 8, 9 inch snowfall forecast.
05:33It's not snow.
05:34Now, I know this looks like a whole lot of nonsense here.
05:38This is something that meteorology students wrestle with in their freshman year of meteorology school of college.
05:46But we're looking up from the ground.
05:48This is the surface.
05:50We're going to draw a little tree here with no branches.
05:53And here, 300 millibars.
05:54This is around 30,000 feet.
05:56This is where I'm going to draw.
05:57I'm not an artist.
05:58This is not going to go well.
05:59And I didn't really expect to do this.
06:00But this is where a 747 is going to fly.
06:03And we're looking up through the atmosphere.
06:05This line, if there were blue, I would select it.
06:08I'm going to go green.
06:10This is the freezing line as you go up in the atmosphere.
06:13And this little nose here, the two lines that we're seeing as we go up, the red line here is the temperature.
06:21And the green line is the dew point.
06:23What I want you to see is this right here.
06:26That is where the rain, the snowflakes are falling.
06:28And they hit a warm area where they're going to melt.
06:30The snowflakes will all melt in that area in Baltimore and then refreeze as sleet.
06:35So that's going to be a major sleet event and not snow.
06:38So here is our actual forecast for snowfall.
06:40We're forecasting around 3 to 6 inches in New York, 1 to 3 in Philadelphia, and only sleet less than an inch in Baltimore.
06:49We're...
06:49We're...
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