Nowcast for Sunday - Tuesday Storm + Snowflake Prediction for Monday and Tuesday

MCPS HAS ANNOUNCED THAT ALL SCHOOLS WILL BE OPENING ON TIME, AND THAT A RE-EVALUATION WILL BE DONE AT 5 AM.

ALSO, THE MAPS ARE NOW OLD, AS I USED THE IMAGE ADRESS, AND NOT A SCREENSHOT OF THE IMAGE, SO THE MAPS DONT SHOW MUCH.

POWER OUTAGES HAVE BEEN REPORTED ALL ACROSS MARYLAND AND THE DMV. HERE IS SOME INFORMATION TO HELP YOU: https://weather.com/safety/winter/news/2020-03-02-what-to-do-if-your-power-and-heat-go-out-in-the-winter#:~:text=During%20An%20Outage%3A&text=Then%20report%20the%20outage%20to,Huddle%20under%20extra%20blankets. https://poweroutage.us/

STATE BY STATE RESOURCES:
https://poweroutage.us/area/state/maryland

https://poweroutage.us/area/state/virginia

https://poweroutage.us/area/state/west%20virginia

https://poweroutage.us/area/state/delaware

ANOTHER UPDATE: As 0z models come in, I will be adding more models. Make sure to go to the bottom of the article to read the latest information on what I think.

UPDATE: Warnings have turned into advisories for the entire county. Advisory lasts until 10 AM Monday.

This storm wasn't really a bust, but it was a bit disappointing, to say the least. We got dry-slotted(who would have guessed) around the afternoon hours, but we still got as much snow as what was forecasted, just in the lower end of totals. Totals ranged from 2-5 inches in the county(as of 6 PM), with more snow northeast and less snow southwest. As of 6 PM, the status for school is open on time, explicitly said by MCPS. They said they will do a re-evaluation at 5 AM, though. For all schools to be canceled(including virtually), offices(in-person) need to be completely closed. However, the criteria for that is much higher than the criteria that are needed for in-person school to close. Now, we will turn into a wintry mix, including ice, and then eventually switch back into snow on Monday. Northern MoCo is in a warning until 6 AM Tuesday, the southern portion; midnight on Monday. The question is: Will we see enough ice and snow to close offices? We will try to answer that using maps.

The NWS shows 1-3 inches of ADDITIONAL snowfall(not storm totals) for our county. The western/southern portion of our county is in the 1-2 inches portion, while the rest of the county(northern-eastern side) is in the 2-3 inches of snow accumulation. With 2-5 inches on the ground, this would bump up our totals to 3-8 inches. However, areas in the 1-2 inches area(for our county) will have additional totals closer to 2" than 1. The closer you are to another zone, the likelier your totals will be similar to theirs. The NWS shows a 60-80% chance of at least 2 or more additional inches, and a 30-60% chance of 4 or more inches of additional snow(see images below).

Chances for 2 or more inches.

Chances for 4 or more inches.

This is a boom scenario, which means totals are higher than expected. This is also additional snowfall onto the snow totals. It shows 6-8 inches for most of the county, with Damascus in the 8-12 inches of snow range. This will probably not happen, but if it did, it would be 5 snowflakes. 

The low end totals show no additional snow accumulation for most of the county, with the northern and eastern portion in the less than 1 inch section. I don't think this will happen either.

Now this is what everyone is watching. The entire county is in the range of at least a tenth, all the way up to a quarter inch of ice. We are also flirting with the 0.25-0.5 inches of ice, which is enough to cause serious and major impacts, including countywide power outages. A quarter-inch of ice is very hazardous and can easily cause power outages, plus break tree branches. A tenth of ice will make surfaces very slippery, plus combined with the snow we have, power outages are more likely. If we see totals closer to the high end, I could very well see no school. 

This model is by the GRAF, which is an excellent, yet relatively new model. It shows 3-6 inches for most of the county, with a small path of the county in the 1-3 inches range. Since people in that range are so close to the 3-6 range, they will likely see totals in the high end of the range, or even might get in the 3-6 inches range. Generally, northeast areas will see more snow than southwest areas of this county. This is the best model for this situation. Storm totals would become 3-9 inches if this played out.

The NAM shows the dry slot fill in with a mix, which falls at a moderate-heavy rate. During the time period of 12 PM - 2 PM, it shows the mix turning into snow for everybody in the county. Then, the snow CONSISTENTLY falls at a moderate-heavy rate for almost 20 hours! Then, the snow starts to taper off a bit, and the snow becomes scattered. It comes back a couple of times and then is gone.

The NAM shows 4-7 inches for the county, with the most in NE areas, like Damascus. Along with the 2-5 inches that fell today, that's 6-13 inches. 

GFS:

The GFS shows the mix/freezing rain turning into moderate to eventually heavy snow, around 10 AM. The bulk of the heavy snow will be between 1 PM - 4 PM, but moderate snow will still linger into the night. The GFS shows 4-6 inches of additional snow, on top of the snow that fell today. This will bring our totals up to 6-11 inches(see image below). It shows the most accumulation in Damascus.

CMC(GEM):

The Canadian model shows the second part of the storm starting as snow, then shows a brief period of a mix, then turns back to all snow. After it turns back to all snow, it shows on and off snow falling. All is said and done by 1 PM Wednesday. It shows an additional 3.5-6 inches falling. Combined with what we have now, that's around 6-11 inches of snow(see image below). The most snow accumulation is in  Northeast areas, like Damascus.

Snowflake Prediction:

2 Snowflakes: ❆❆

(Special Version: 50% closure[school buildings], 25% chance for offices to close)

Tuesday:

12:10 PM Update:

As you can see by the arrows, the snow band is generally moving in a southeast direction. In the next couple of hours, if you haven't seen a heavy band yet, you probably will see it soon. Snow is still persisting in Frederick, Fairfax, and even Washington counties. Half of that snow band is still in PA.

11:50 AM Update:

The snow axis has moved west, which means it's looking better for snow accumulation in the DC area. Moderate snow still continuing somewhat west of us. One long snow band from the north, hitting Loudoun and Fairfax counties plus MoCo(mainly northern and western areas) is generally moving south, but the radar shows unpredictable movements. Sudden drops in visibility and fast snow accumulation on roads are likely in these heavy bands. We will likely see another coating, all the way up to 2 inches in the next couple of hours. Winds are gusting 25-40 MPH, blowing snow.

8:30 AM Update:

Winter weather advisories have been extended for everyone until 1 PM because of lingering snow bands. Snow is accumulating rapidly on any untreated surfaces, due to the really heavy snowfall rates. I feel like by the end of the storm, about everyone should have totals similar to what was projected earlier. Visibility is really low outside. Avoid any unnecessary travel. Winds are also picking up and drifting snow. These are near-blizzard conditions.

Monday:

10:30 PM Update:

The main bulk of this event is over. We will see some snow accumulations, but it will be mostly light, with additional snow accumulations only up to one inch. It is super icy and snowy right now, but even then, crews will have some time to work on the roads. Winter storm advisories have been extended to 9 AM Tuesday, but snow showers will likely persist for much of Tuesday too. The latest NAM(3km) shows snow showers persisting until around early Wednesday morning(12-3 AM). It only shows 1-2 inches of additional accumulation though. My prediction for school tomorrow is 2 snowflakes, meaning that offices will likely be open(25% chance of closure) and school buildings have a 50% chance to close. I am not really leaning either way though. 

5:30 PM Update:

New bands are forming all across the DMV. Bands far away shouldn't be tracked because they are getting stronger and then weaker and it's not reliable to do so anyway. We have many new bands forming as we go throughout the evening and night hours. Heavy snow bands are unleashing very low visibility and even snow accumulation on treated surfaces. My neighborhood roads with salt still had snow accumulation as we got the bands. Salt is not becoming as effective. If you are traveling, it is going to be very hard to see and snow will rapidly accumulate on the roads. Stay safe everyone.

5:00 PM Update:

These heavy snow bands will be coming in waves. Once one of them is here, it will snow at a heavy rate for some time, then start to snow at a less heavy rate. We still will have snow during those periods when we are waiting for the bands, so don't worry! This will keep happening as it goes through Tuesday. Snow coming down at a heavy rate right now. In fact, it's snowing so hard that parts of the LWX radar are being blocked and are showing dry conditions, when in fact it is snowing there!

4:00 PM Update:

The heavy band has made it into our county! Over the next hour, it should be moving in a southwest direction, as the arrows point. Expect a sudden burst of heavy snow and visibility to suddenly drop.

3:40 PM Update: 

Multiple heavy bands from the north are moving into our area and pushing down south. The arrows represent the direction the bands are going in. We will see some of these bands. All of these bands have very heavy snow and are likely to fall at rates of 1-2+ inches of snow per hour.

3:20 PM Update: 

The storm is throwing even MORE heavy bands at us from PA! The areas in the circle that says 1-2" are right now seeing the snow bands from PA(dark blue represents heavy snow). These snow bands have 1-2"+ per hour snow rates! Areas in the band will see a sudden and drastic decrease in visibility as heavy snow falls. The bands are making their way to the south! The storm is throwing everything it can at us.

3:00 PM Update:

This is what the radar is showing right now.  The circled area is where the dark blue colors are, and that indicates that "thumping" is happening in that area, otherwise heavy bands. Areas in those bands can expect snowfall rates to fall at 1-2 inches per hour! They seem to be moving south in our direction, so I think that at least our northern section of our county will see that heavy band.

2:20 PM Update:

The storm system has become vertically stacked. 700 and 800 MB lows are over the surface low. What does this mean? This means that this storm is not going away anytime soon, and this also gives it the potential to stay through Tuesday. This will likely result in more heavy snowfall.

1:50 PM Update:

The atmosphere is cold enough for almost everyone in Maryland to see snow now! The heavy banding in SE PA is rotating into Maryland, going in an SW direction. But, this is more impressive. The European Model shows 5-8 inches of ADDITIONAL snow after the storm is all said and done. Models have been trending colder for our area, but even then you should be skeptical of these numbers. Didn't want to show precipitation on modeling cause it is happening right now. Still an encouraging sign for snow lovers, regardless!

10:45 AM Update:

The fact that they haven't called anything yet makes me less confident that they will do anything...

9:50 AM Update:

Winter weather advisories have been extended until midnight on Tuesday. Conditions are just getting worse and worse, as we turn into snow in the afternoon hours. Precipitation is going to start to pick up, along with gusty winds. This increases our chance for an early release to 67%.

9:30 AM Update:

I have reports from all over the county about how icy and snowy it is outside. There is already a sheet of ice underneath any surface, plows came to my neighborhood 3 times and dumped pounds of salt, and yet it's still so icy with snow. Freezing rain picking up a bit now, as temps are well below freezing. Damascus is super icy, and many roads in Northern MoCo haven't even seen a plow yet. I will increase it to 65%. 

9:00 AM Update:

Light to moderate freezing rain falling in Gaithersburg, not really melting the snow because of cold temps, should switch over to snow in the afternoon hours. I will now increase my chances of an early release to 55%.

8:30 AM Update:

Models are showing heavy bands of snow during the afternoon hours. The coastal low is closer to the coast and is getting pulled back west. This will result in colder air(temps right now are already colder than what models show), stronger and gustier winds, snow bands and showers through Tuesday, additional accumulation, and if we start as a mix, we will turn into snow by 10 AM - 2 PM. I think that we will see totals like in the snow maps we saw on Saturday, even if it is on the lower end(5-10 + inches). Some snow will probably fall in the morning hours, but the main bulk of the accumulation should be in the afternoon. This will cause big impacts on the evening rush hour. Not to mention, the gusty winds that will be blowing snow that's falling and on the ground, lowering visibility and increasing the risk of an accident(if snow on the ground gets blown into your car, your window can break and injuries can easily occur). I am almost CERTAIN advisories will be extended to at least go through the afternoon hours, especially in NE MoCo. We could even see warnings(if we get a little bit more than expected)! I still won't change my percentage UNTIL we start to see our snow fall, though, but once it does, and if everything seems right, I will increase it.

7:20 AM Update:

Right now, we are in a lull of precipitation. As the day goes on, we will start to see snow. About 1-3 inches are expected, with 2-4 inches in the NE part of the county. Snow will have no problem sticking though, as temps are WELL below freezing. The county has announced that there will be a full day of school, but they are monitoring conditions and will make an update if it is needed. This means that there is a chance for an early dismissal, however, until we start to see our main precipitation come over and see how conditions evolve, I will have to leave it at a 50% chance.

Sunday:

11:45 Update:

With almost all of the models showing an additional 3-6+ inches of snow for our county, the bulk of it falling in the afternoon, I think we can get an early release. We could easily still get a closure, but I still think that I don't want to lean either way because they are going to try to fit in as much school as they can. It's STILL snowing in Gaithersburg, and even though we are more likely to turn into a mix in the next couple of hours, there's already 0.5-2 inches of snow on the ground from snow accumulation after 5 PM. It's going to get REALLY bad around the afternoon time, and even for offices, I think that not calling an early dismissal would turn dangerous fast in the evening commute. Traffic could be endless. Overall, I think we will see an early release but remember... this is my first time predicting virtual impacts. I might be wrong. Plan for a full day of work/school.

Why early release chances are included: Snow is more likely to fall in the afternoon hours, due to a higher chance of the mix fully turning into snow by then. Ice is going to make things very difficult to clean up, as in northern MoCo, the lights keep flickering, and we even haven't turned into freezing rain yet. 

10:40 Update:

Our neighboring counties are starting to make the call, which is good for us, because if all of the other counties do something, MCPS will be pressured into doing something. Frederick County has completely closed schools, even virtual learning. Prince George's county has called an early dismissal for online instruction. If a county south of us does something to the school day, that is good, because the storm impacts them less, whereas compared to us, we have a higher impact. I think an impact is very plausible and possible at this time.

9:50 Update:

Right now the coastal low is forming around Myrtle Beach, South Carolina, and it is going to go to Theta-E, which is located east of Maryland, right along the line between the ocean and the USA. This is good for snow lovers because this makes coastal storms stronger. It is further south than the models were showing, possibly giving us more snow. And by now, the warm front at 700MB right along I-95 was expected to go north of the PA line and give us a lull, but snow is still falling in Northern MoCo. I feel like we will see more snow tomorrow, and there will be a decent amount.

Original Statement:

I honestly think that even with the models showing less snow, with the snow we have right now, the Monday commute will be a mess, with wintry weather continuing into Tuesday. This is a long-duration type of storm, so snow and ice will keep piling up.  It could really go either way. Precipitation will be mainly scattered right now(7-9 PM) as we turn into a wintry mix. Precipitation will switch back and forth. Right now, we are seeing a sort of lull in a lot of the county. Main precipitation will come back after 9 PM, snow or wintry mix. If heavy bands from the north wrap around and travel south enough to get to us, we could easily see lots of snow. I will keep updating this as the hours go on.

Final Forecast(not nowcast) and First Snowflake Prediction for Sunday-Tuesday's Storm

BREAKING NEWS: MCPS HAS JUST ANNOUNCED THAT VIRTUAL SCHOOL LEARNING CAN BE CLOSED IF WEATHER CONDITIONS ARE SEVERE ENOUGH OUTSIDE. 

First, let me just say that this storm will be the most significant storm we have had in a while, almost 2 years! Now is it a blockbuster, snowpocalypse-type storm? No. But it will still be very disruptive. The models have been really jumpy on snow totals, because of the coastal low that will fall on Sunday night. These kinds of storms require a nowcast because it is so difficult to accurately predict how much snow the coastal low will help us drop. This storm is a "Miller B" type storm. These storms can produce massive amounts of snow if everything is aligned right or just a nuisance. The 2010 blizzard(Snowmageddon) was a Miller B type of storm. This storm will last 48-60 hours, and there will be two parts: the first part on Sunday, and the second part on Monday - early Tuesday. The precipitation course of this storm will be mostly all snow, with some mixing + a dry period/lull occurring on Sunday night-Monday morning. The mix will turn back to all snow though. This isn't a full-on snow gradient type of storm where Damascus gets a foot and Bethesda gets 3 inches, but the general consensus is that the more north you are, the more snow you will see. However, areas surrounding Baltimore are expected to get more snow than the rest of the DMV. There are winter storm warnings for both parts of the county, and for the rest of the general DMV. The warning states 6-12 inches for Northern MoCo(until 6AM Tuesday) and 3-6 inches for Southern MoCo(until Sunday night). Anyways, let's look at some models and maps now.

GFS:

The GFS shows the storm starting as snow, then turning into a mix/rain around Monday, then shows it turning back to snow for the rest of the storm. It shows 8-10 inches of snow that was totally accumulated from this storm(not what is on the ground)(see image below).

CMC:

The CMC shows our county staying all snow, with some heavy snow bands. This would be a high-end situation where we get more snow than expected, with 12-20 inches of snow. (see image below). However, the bullseye is SSE PA/Northeastern Maryland(Baltimore).

RGEM(outlier):

Now I won't show any maps for this, because the totals its putting out are absurdly high and I don't want to overhype anyone. You can see them for yourself on tropicaltidbits.com, but do not count on that falling. They are blockbuster snow totals, and if it was indeed going to happen, a lot of the other models would show numbers close to that too. However, that being said, this is what Tony Pann, a senior Meteorologist at WBAL 11, said: "Strong LLJ from the NE will bring a lot of moisture into a cold air mass... so maybe!" It shows very heavy snow bands coming and cycling around our area, bringing huge snow totals. I don't think we will see numbers even remotely close to that kind of numbers, but I would love to be wrong.

NAM 12 KM:

The NAM shows us starting as snow, and then turning into a mix, and then turning into snow again before ending. It shows 7-10 inches of snow(see image below).

European:

I couldn't find a GIF for the European model, but I will try to explain as best as I can. It starts as snow, and continues like that until Monday, where it changes to a mix, and then back to snow, which ends on Tuesday. It shows 8-12 inches of snow, with more snow in NE areas and less in SW areas, assuming a 10:1 snow to liquid ratio.

UKMET:

The UKMET shows 9-13 inches of snow(10:1), depending on where you live. It favors north, but not specifically east or west.

MAPS:

Fox 5:

This map shows 8-12 inches for the northeastern side of the county, while it shows 4-8 inches for the southwestern side of the county. Since the 4-8 inches of snow side is so close to the 8-12 inches side, areas there(4-8) will see totals like 7-8 inches, I wouldn't be surprised if they get more than 8 inches.

WUSA 9:

Disclaimer: They have 2 maps. I will show both maps and then add up the totals.

This is for the first round, which ends at 7 PM Sunday. It shows 3-5 inches for all of the county.

The second round, from Sunday night to Monday, shows 1-3 inches for most of the county, and 3-6 inches for the really upper part of MoCo. Overall, for most of this county, WUSA 9 predicts 4-8 inches, while for the really northern part, 6-11 inches of snow. I feel like some areas in the light blue could see totals at or over a foot of snow though.

NBC 4:

This map from Doug Kammerer shows 4-8+ inches of snow for our county, with Damascus in the 6-10+ inches of snow range. The + means that more snow could fall, but whatever the range is listed is more likely.

ABC 7:

ABC 7 shows 4-6 inches of snow through early Monday. I assume this is not the storm totals and the forecast only for Monday. I agree with this map, in terms that everyone gets 4-6 inches of snow on Sunday. However, they say that 1-4 inches of snow will fall on Monday, and along with the 4-6 inches, that's 5-10 inches of snow, totally. They say that locally, you can expect 4-8 inches of snow, with higher totals north and west. Overall, I agree with this map.

Capital Weather Gang:

This map shows 5-10 inches for the upper half of the county and 4-8 inches for the lower part of the county. However, the 5-10 inches area went up a little bit north, but nothing significant, at least compared to their last map.  In the 5-10 inches area, the boom and bust potential are the same, while in the 4-8 inches area, the bust potential is 10% higher than the boom potential.

National Weather Service:

Expected:

The NWS shows 6-8 inches for almost the entire county, with 8-12 inches in upper Damascus. They expect some ice accumulation to come out of this too though(image below).

The NWS shows 0.01-0.10 inches of ice for the majority of the county, with the middle of the county getting 0.1-0.25 inches of ice. The ice won't be the main problem, it will be the heavy snow, and I don't think the ice will cause power outages.

High-End amounts(boom scenario):

This map shows 12-18 inches of snow for almost the whole county, with a small sliver of southern MoCo in the 8-12 inches range. 

Low-End Amounts:

This map shows 4-6 inches for the entire county, in case we get a bust. This still shows a moderate impact event.

So overall, how much do I think we will get? I think for the southern part of MoCo, they will see 4-8 inches, and for the northern part, we could see 6-12 inches(though I think most areas will see 10 or less inches). However, there are 3 scenarios. 

Scenario #1(most likely): We see 3-6 inches of snowfall on Sunday, and as we go into the night, the snow will turn into a mix, and then we will see a dry period. Then, as we transition into a coastal low, we turn back to all snow, and it stays that way until the storm tapers out. 3-6 inches of new snowfall in northern MoCo, and 1-4 new inches in Southern MoCo. Totally 6-12 inches for northern MoCo and 4-8 inches in Southern MoCo.

Scenario #2(bust, less likely): We see 3-6 inches of snowfall Sunday, then as we go into the night, we either: have too much warm air and see rain or get dry-slotted(being dry slotted is more likely). The coastal low doesn't transition well enough to get more snow on Monday, and we don't see much more snow accumulation. 4-7 inches throughout the county, but less will be on the ground.

Scenario #3(boom, more likelier than bust but still less likely than expected): We see 3-6 inches fall on Sunday, and then we have more cold air and moisture than what was expected in the night, continuing the snow(no mixing), with a very short period of a lull, and then as we go through Monday, we see many heavy bands of snow, possibly dropping 1-2 inches at a time, and we see snow fall until Tuesday, giving us 6-12 inches more along with the original snow that fell on Sunday. This will bump our storm totals to 10-20+ inches of snow.

SNOWFLAKE PREDICTION:

3.5 SNOWFLAKES(for Monday)

I am going with 3.5 snowflakes for this storm because I think with 4-8 inches of snow, and even more in northern MoCo, any in-school activity/work will be completely shut down. Roads are going to be very slick and icy + snowy, not to mention the long duration of the storm, which will help continue to worsen roads. We also will get some freezing rain, just to make matters even worse. I think offices will close too, we haven't seen this type of snow in a LONG TIME. Although I don't think we will lose power, MCPS said that if offices and schools were closed, virtual learning would be closed too. The reason this is not 4 or 5 snowflakes is that if we bust and our coastal low doesn't deliver, we probably won't see a closure. I am being conservative with my prediction, but I am leaning towards no school. This is not my final prediction, so stay tuned for the next one tomorrow!

In conclusion, there are many things that could go wrong with this storm and we don't see much. However, I feel like we are likelier to see a boom than a bust, even with that being said. I feel like we will see some heavy bands throughout Monday. Snow will RAPIDLY accumulate on any untreated surfaces, due to the cold air that has been in the region for the past couple of days, and temps will be below freezing when it starts to fall. Any in-person thing will probably be canceled and will be switched to virtual(if it can). This will be a long-duration storm, so the impact will be felt through Sunday to at least Tuesday. We will see enough snow to sled, and build a snowman. This is a pretty significant storm. However, I don't think we will see power outages, because we aren't seeing wet, heavy snow. Please avoid any non-essential travel, and if you do, make sure to be very careful and drive slowly. Make sure to also keep an emergency kit that includes jumper cables, a snow shovel, something to wipe off snow, a blanket, a first aid kit, sand or cat litter, a radio, sufficient food, a water container, extra batteries, paper towels, and extra clothing. Check out more for what you should do here: NWS Winter Safety Kit. Overall, this storm is not just a couple of inches with minor impacts, this is an impactful, dangerous storm that you should take seriously. Stay safe, and I hope you enjoy the snow!

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.

Mon-Tue Storm Summary and More Weather News

Unfortunately, this storm was a bust, mainly in terms of snow totals though. 1-3 inches was expected in NW MoCo, and instead they got 0.5 inches. I myself, in Gaithersburg, have measured 1.5 inches of snow, and a tenth of an inch of ice accumulation. The advisory is still in effect for the entire county until 1 PM, expecting up to a tenth of new ice accumulation. The main reason we had a bust was because we had a dry period where we didn't see anything, and we got somewhat robbed of our moisture. For the freezing rain, there was enough moisture for it to fall, but we didn't get as much moisture as what was expected, during what was supposed to be the main time for ice accumulation. All in all, it wasn't too bad, we still got something, unlike the March "storm" in 2019. It started as sleet for upper MoCo and maybe rain for Southern MoCo, then everyone switched to pure snow, then had a dry period, with mixed precipitation scattered across the area, then we had freezing rain for a while, and then some areas had rain, and now its pretty much over. I have some good news though. The snow drought has ended in DC, where 0.3 inches of snow was measured!  It is very icy and snowy out on the roads and sidewalks, so if you have to travel, slow down and use caution(black ice is the main threat here). 

You know the Wednesday/Thursday storm I was talking about? Well, it's pretty much disappeared to our south. We won't be seeing any actual snow, but we may just see some snow showers/flurries. The more southern you are located, the more likelier you will see some light snow from the Wednesday-Thursday storm. There could be a last minute north trend, but even then, I don't think we will see too much snow from it. Still something to keep watching though.

However, there's ANOTHER winter storm threat, on Sunday-Monday. I won't go into too much detail, as we are pretty far out, but it could bring some significant snowfall. Even if this threat misses, we have a split polar vortex, which will supply Arctic air for us, and will keep the active, favorable pattern into February, so we have more chances to see some snow. 

The NWS shows a slight winter threat for the entire region, with medium confidence, and what seems to be a low impact.

That's pretty much it for now, I will make a new post about the Thursday storm in the next 24-48 hours if anything changes, but I don't think it will. I will also make a new post about the Sunday-Monday storm in 2-3 days!