Weekend snow threat features more questions than answers

You've undoubtedly heard the buzz around town already of the potential for big snow this weekend in the D.C. region. The question is, of course, is it true? The simple answer is, 'yes,' that potential exists, but going from a potential threat to reality is not an easy task. This winter in particular has had several 'potential' big snows just miss. Notably, the January 7th storm slid just south of our region, giving parts of central and southern Virginia over a foot of snow while most around the immediate D.C. metro area ended up with less than one-inch.

Forecasting snow events is particularly difficult at this time of year as well, with the sun getting higher in the sky and temperatures generally on the upswing with the journey into spring well underway. Washington, D.C. has done big March snows in the past, but also has a history of underperforming in spectacular fashion on occasion. Recall the infamous "snowquester" storm of 2013, when a forecasted blizzard turned into nothing more than a dusting, and our very own Tucker Barnes ended up sitting himself in a corner.

I will level with you straight - right off the bat here. We do not know what is going to happen this weekend in terms of if we will get any snow or not, and we do not know how much anyone will get if we do get snow. All we can do is highlight an area that is at risk for snow, which you can see above, but the simple fact is not everyone in that zone will get snow. What do we know? Well, timing wise various weather models seem to all be a consensus that if a storm were to happen, it would happen sometime between Saturday night and Sunday afternoon - so that is your timeframe of concern for those with flights or planning activities this weekend. The other thing we can say with pretty good confidence is that it will be cold this weekend, feeling much more like a February weekend than a mid-March weekend.

So what's the problem? Why don't we have the answers yet? It has a lot to do with the very nature of potential big storms, and the fact that the usually come out of the Pacific Ocean, which is where the potential weekend storm is at this very instant. The problem with weather models is that the need good, accurate and updated data to be fed into them in order for the model to have a good output. When a storm system is close to or over the United States, we have plenty of ground based weather observation units, weather balloon data, good data from thousands of city to city airplane flights. The problem with a storm over the ocean is the data is not as good, or rather not as frequent. The data being fed into the models comes mainly from satellites and widely spaced buoys plus the occasional airplane or passing ship. The point, data is not as widespread over the oceans as it is closer to land, and as a result more estimates are made. This is actually one of the reasons the hurricane hunters exist, as they fly into developed storms to get a clearer data picture of hurricane over what forecast models are estimating, which in turn helps with the forecast.

As a result of these estimations, forecast errors with specific details like the track of a storm are more likely the farther away you get from the current day in the forecast. The result is models all differing on the track of the storm, and different runs of the same models appearing to 'jump' or change the track of the storm with each model run. With the potential storm about five days away, this is currently what is happening in the forecast model world. Take what you see in the image above, you have two models both giving a forecast for 2 p.m. on Sunday afternoon. The on the left is showing a suppressed storm track, meaning any snow stays to our south and we just have a cold weekend here in Washington. The one on the right is showing a more northern look a bit closer to D.C. which would mean more accumulating snows around the region. The current issue from a forecast standpoint is we are not getting enough consistency from the models yet to make any forecast calls that we would feel confident making. This is a very different storm from the blizzard of January 2016 where the models were all in agreement a week out and held steady with the big snow forecast. We do not have that here. So when do we think we could see a bit more consistency in the forecast? Best guess would be Wednesday night or Thursday, when the storm itself gets close enough to the West Coast of the United States that weather models will have a much clearer picture from a data standpoint of what we are working with storm wise.

The weekend storm is actually only one of three systems that will affect the region over the course of the next week that will have the potential to bring wintry weather to the D.C. area. The first is Friday, as cold air starts to spill back into the region following what will be a very spring-like Wednesday and Thursday. While this system may impact the Friday morning commute, it probably will not have a big impact on the D.C. and Baltimore metro area due to it mixing with rain combined with some warm ground temperatures. As things stand now, best chance for any significant accumulation with this system would be over the mountains to the west and perhaps north of the Mason-Dixon Line as well, where temperatures will be colder.

Beyond the weekend system that we already touched on, various weather models are also hinting at a potential system sometime on Monday night into Tuesday. More so even than the Friday system, this is a system to keep an eye on since it will come at the tail end of a cold pattern instead of a breaking warm pattern. This is important because the ground temperatures would be more likely to support accumulation, as opposed to the system on Friday for example. Since there is still plenty of uncertainty for the weekend storm, you can bet there is even more uncertainty with something early next week too, so be sure to check back for the latest later this week.

At this point, all we can advise is that you stay informed. At this time, there is no need to go clear the store shelves or go out and buy a snow blower, the confidence in the forecast is not high enough yet. As mentioned above, Thursday is probably the day we will have a pretty good idea of whether or not we are looking at snow around the D.C. region. Then, if it gets to that point, we will begin the tough process of figuring out just how much we could get. Until then, keep checking in with the FOX 5 Weather Team on social media and tune in to FOX 5 News for the latest updates. This is a tough forecast, and one that will undoubtedly need updating over the next few days. Stay tuned!

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