Sunday-Tuesday Storm Update

 

Winter Storm Watches for almost the entire DMV.

This storm has consistently held up against the will of time, and now, you can expect a snowstorm. There are winter storm watches in effect for the whole county, and for almost the whole DMV(see image above). They expect 5 or more inches of snow to fall. This storm has two parts: the first part is on Sunday, and for this part of the storm, meteorologists are pretty confident that this part will drop a couple of inches, but the next part will determine whether we see double-digit numbers or just 2-4 inches. The next part takes place Sunday night - Monday night or maybe even through Tuesday morning. A coastal storm will form near the Carolinas, which may continue moderate-heavy snow throughout Monday-(possibly) Tuesday, increasing snow totals and causing significant accumulation. This could be an all snow event, but another question on the table is that we might see some mixing/ice. We will switch back to all snow though, but the question is "Will we see more mixing or more snow?" Overall, this storm will be significant, and probably will be the best snowstorm since 2019. 

GFS:

The GFS shows the storm starting as snow, then transitioning into rain, and then shows it being all snow for the remainder of the storm. It shows 6-11 inches of snow for our county, with higher totals north of us (total accumulated snow, not what is on the ground though).

GEM(CMC): 

The GEM almost shows an all snow event, with a brief period of mix around 7 AM. Now, I don't trust these big snow totals, but the CMC shows 10-20 inches(totally, not what's on the ground) from this storm. I feel like these snow totals might be too big, but I would love to see these totals. The bullseye are areas closer to Washington DC.

I couldn't find a GIF for the European model(because Pivotal Weather decided not to work), but it shows 4-9 inches, higher totals in the northern areas. It shows an all snow event for the northern half of the county, with some mixing in the southern areas, around 1-7 AM.

Now let's look at some local maps!

FOX 5:

This map shows 4-8 inches for the whole county, and for most of Maryland, with 2-4 inches in southern Maryland and 8+ inches for western Maryland. From Mike Thomas: "Here is our FIRST CALL snow map for the Sunday/Monday storm. Going pretty conservative compared to guidance...but I DO at some point anticipate adding a 8-12" zone somewhere on this map. But since models still disagree on where snow will fall Monday, we'll play it safe for now." The models show more snow than 4-8 inches in a lot of the places in that range, but since this is the first call, you have to play it conservative and not go for the big totals.

Capital Weather Gang:

As you can see, the northern half of the county is in the 5-10 inches of snow range, while the other southern half is in the 4-8 inches range. They have medium confidence in the northern half, while low-medium confidence in the southern half. They are pretty sure of 2-4 inches of snow falling on Sunday. Although on the map the bust possibility is higher than the boom, I think this storm has a higher chance of a boom than a bust.

National Weather Service:

The NWS shows 4-6 inches of snow for all of the county. However, they are probably playing it conservative, and will likely increase totals if models hold. 

This is the high-end scenario; the boom scenario. It shows 12-18 inches of snow for our county, and most of the general DMV too. These are big amounts and would cause major disruptions. However, this isn't what is expected to happen; just a worst-case scenario(best-case if you are a snow lover).

This is the low-end scenario; the bust scenario. This would happen if the storm busts and we either get dry-slotted(no precipitation falls) for long periods of time or if we don't have sufficient cold air.

This is the ice accumulation map. They are expecting 0.01-0.10 inches of ice for most of the county, with some of the southern parts in the 0.10-0.25 inches range. The more ice you see, the less snow you will see. I personally think there will be less ice than what is forecasted, but I think they are trying to count in the mixing.

At the time of writing this, there are no new maps for this storm. I will make an update tomorrow. These totals are warning levels and will cause significant disruptions. We will see accumulating snow on Sunday, for sure, maybe some on Monday. Exact snow totals are unknown at this point, due to the second part of the storm, which has less confidence on happening.