Severe Weather and Snow Threat Thursday - Friday Update

We have a needed storm that is coming up tomorrow and will last into Friday afternoon before tapering off. And there is the potential for some snow as a secondary cold front pushes through the area on Friday. Other than the snow, why do I say this is well needed? Well, we haven't had much precipitation in the area since the end of February. Up to 2 inches of rain could fall in our region! This is well needed for plants to thrive. Although we aren't in a drought, it has still been a while, and it will be good for everyone. And, as you may have noticed by the title, there is the possibility for SEVERE WEATHER on Thursday! I am pretty sure you would have heard about the crazy and dangerous weather going on in the really southeastern part of the US.

A high risk and a 45% chance of a tornado occurring for any one location in that area are nuts! In those areas, significant strong tornadoes(EF2 and above) are likely. And on Thursday, there is a chance for some severe weather in our region; locally! I'll go above it below.

Our whole region is under some sort of color! For most of Maryland, some non-severe isolated thunderstorms are possible. However, in our western and especially southwestern areas, a marginal risk for severe thunderstorms exists. In our extreme far SW suburbs of the DMV, a slight risk for severe thunderstorms exists, including a small risk of an isolated tornado forming(2% - 5%). A marginal risk means that some severe storms could be spotty, but will be limited in duration or intensity. There is, and I cannot stress this, still a risk for tornadoes, damaging wind, and hail in areas in a marginal risk. It is just in those slight areas where more, stronger tornadoes, more widespread and damaging hail, and winds are likelier. The main reason why parts of our area are in the "marginal" zone is that there is mainly a risk for hail.  The biggest impacts are in the Carolinas, where widespread, damaging tornadoes, hail, and wind are expected. If your area is in any color on the SPC map or any specific place(s) I mentioned, get ready for dangerous severe weather. Make sure you have enough food and water to last for at least a week, have a shelter/safe spot in your house, and have a radio or some sort of device that can get up-to-date warnings and watches issued by the NWS.

Anyways, back to the snow aspect of this storm. We will start to switch over into wet snow in the early morning hours of Friday and will keep snowing until it starts to taper off. As you might have expected, areas north and west of MoCo will see more hours of snow. Over the past 2 days, the storm has been trending more south. As we switch over into the snow, it may be mixed with sleet/rain. However, as the cold front pushes SE, it should be primarily snowing if you live in MoCo, and generally most of the area. Winds may gust of to 20 mph, so conditions will get worse on Friday. The models have been doing some wacky stuff with the snow amounts though, and I will be looking at them regardless.

NAM(12km):

The NAM shows moderate-heavy rain before we start to switch over to snow, and then that snow band pushes southeast. However, around 8am Friday, I do want to point out something. It shows heavy snow in a lot of Southern Maryland. There is one thing wrong with it. If you look at the 540 blue line, it sets up right around Rockville(the thing about this line I will say now applies to all of the models). Generally, any area below that line(if they aren't bordering the blue line) will not be snow and instead sleet, or cold rain, since temps are above 32 at this time for most of the area(even for those who are above the blue line). This will cause an error in the snow totals, and since this model shows heavier precip in Southern MD, and shows it as snow, will cause a ridiculous uptick in snow totals. Take the snow maps I show with a grain of salt.

This snow map is utterly ridiculous. It shows up to 6 inches of snow in some areas of SoMD. That, will not happen. And even more stupid, is that almost Frederick county has no accumulating snow at all. Yeah, this won't be playing out at all. It shows a coating to a little over an inch of snow in MoCo, with the most snow somehow in SE MoCo. This will not happen.

GFS:

The GFS shows much heavier precip compared to the NAM. It shows heavy rain hitting us before that cold front moves down and switches us over into heavy snow, before eventually tapering off. Now, the GFS does a much better job than the NAM with its 540 blue line, as most areas that are below that blue line are shown as rain, and areas north are shown as snow. However, I still am a little bit skeptical of the snow map.

The GFS is much better than the NAM, but it still is a little bit ridiculous with the highest totals in our area being on eastern Anne Arundel and Northern Calvert County. In MoCo alone, a little less than an inch to a bit more than 2 inches is shown by the GFS. At least it shows more than an inch of snow in Washington and Frederick counties. Even though the GFS does show the heaviest precip once the cold front pushes down in Anne Arundel and Calvert Counties, and dynamic cooling will likely be there, I still think it's still wrong, as north and west areas will see the cold air that is required for wintry precip first, giving those more snow. They will also be able to maintain snow on the ground longer. However, it definitely is on to something with that area getting the most snow in our area, and it is something to watch. Either way, the highest snow totals from this storm north and west of Montgomery County. We want a stronger storm and not a weaker one, even if the jackpot totals(southern New England) aren't pushed south.

Euro:

The European shows heavy rain before the transition to snow as the cold front snow. However, it shows the heavy precip moving out of here before the cold front has come through our area enough to cause snow. It still shows us having some light-moderate snow, but it won't amount to much.

It shows up to a coating of snow, with the most snow in our region in our NW areas. Now, I think the European model is the most accurate out of all of the models in terms of where the highest totals will be; north and west of MoCo. I don't agree with how low they are though, I think the cold front will be pushing south fast enough for some of the heavier precip bands to be heavy snow. We will see though.

So since this is a rain to snow event, and it will be raining for the most part on Thursday, I will make an update on Thursday, this time with live radar and condition updates, including some models. I won't make a snow forecast until tomorrow, since there are so many things that could go wrong and we don't get anything or something goes better than planned and we get much more snow than expected. Right now, I am thinking of a trace to an inch in southern MoCo and a coating to 2 inches in Northern MoCo, with some isolated areas, possibly pushing 2 inches. 3" is not out of the question if the cold air pushes in faster or the heavy precip lingers for longer.