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!

FINAL FORECAST FOR MONDAY-TUESDAY STORM

The NWS has issued a winter weather advisory for the entire county and down to Prince George's county,  expecting up to 2 inches of snow and up to 0.1 inches of ice. But, I think we could see more than 2 inches, and maybe even 3-4 inches in some areas of our counties(mainly northern areas). The models have been consistently trending colder for our area and also giving more precipitation, so snow total amounts have increased. The storm will arrive at 5-7 PM, and the main bulk of our wintry precipitation would be between 8:30 - 12 AM, including snow and sleet. During this time period, expect moderate-heavy snowfall rates. When the snow starts to fall, it will be dark, meaning that temperatures will be at least a few degrees cooler, plus no sun angle to melt the snow. This helps our chances of starting as snow/sleet. Surface temperatures are more than cold enough to support ice and snow on it. It is going to be very messy, to say the very least. If you are traveling north and west, please be even more careful, especially near the warning areas, because they are expecting enough ice to damage power lines and make tree limbs fall. Even if you are traveling south and east, still stay careful because although conditions won't be as bad as compared to north and west, they can still be bad enough to cause trouble. The winter precipitation is supposed to continue through Tuesday morning, but after 8 AM, all of the precipitation will clear up. There might be some scattered freezing rain/showers though. The heavier the precipitation is, the more likely that precipitation will be wintry, and the lighter, the more likely it is rain. And I must emphasize, just because you see one type of precipitation now doesn't mean you will see it for a longer period of time. Precipitation types will be constantly changing, so be vary of that. 

The NWS shows 0.1-0.25 inches of ice for a little more than half of our county, while the rest of the county is in the 0.01-0.1 inches of ice area, mainly in the southern and surprisingly more western areas. 0.25 inches of ice is enough to cause a winter storm warning.

The NWS shows 2-3 inches of snow for most of our county, while scattered areas of the county are in the 1-2 inches of snow area. They also predict the precipitation(just in general) to arrive at 5-7 PM.

This map from the Capital Weather Gang shows 1-3 inches of snow for almost the whole county, with a very small portion of it in the coating to 2 inches of snow area.

NBC 4 shows 1-2 inches of snow for the southern quarter of MoCo and 2-4 inches for the rest of the county.

FOX 5 shows 1-2 inches for half of our county, specifically the NE part, and the SW part is in the "Sleet to Freezing Rain" section, where a coating is possible, but that's about it. I couldn't find any snowfall maps for ABC 7 or WUSA 9, other than what they think. 

WUSA 9 shows a Trace-1" of snow for our area, with one super NE section of the county in the 1-3" of snow area. I don't agree with this map, because almost every other map has more of the county in the range of over an inch.

ABC 7 shows that the mix arrives around 1-5PM, and then during 5 PM Mon - 5 AM Tue, a mix/snow will occur for us and the general DC area, with rain south and east. There will be slick spots on overpasses during this time. At 5-10 AM, there will be lingering slick spots, with a mix/snow and rain south and east. They didn't say much else about the amounts, other than "A wintry mix of rain, sleet and some snow may lead to an inch or two slushy snow along with a glaze of ice." They didn't give any maps though, other than the impacts by timeline map.

In conclusion, just be careful about this storm, especially north and west of MoCo. It won't be significant, but it will be enough to cause some minor disruptions. I do think a boom is actually quite likely at this point, around 35%-55%(a boom is when there are more snow and ice than what was forecasted, and if it's more widespread). As for impacts, for school closures, I think there is a 35% chance of no school and a 40% chance of a delay(however I am not sure how that would work out). If there is no power, there is no school regardless of what the county says. 

(possibly final) Monday-Tuesday Storm Update

 The models have actually trended colder for this storm, giving us a higher chance to see winter precipitation. And although we are close to the storm, not many maps have been made yet. So we will also be looking at some models, like the NAM 3KM and HRRR + plus the American and European model. But, this storm is going to be very messy. Since the temperatures and dew point are so close to freezing, it is going to be difficult to predict what precipitation we will be starting as until the precipitation is very close to us or is already falling. And I also expect precip types to switch and change rapidly during the course of the storm. This storm is going to be more impactful the more north and west you are. There are winter storm watches in western Maryland and NW Virginia, where significant and dangerous ice accumulation is expected. I think that the watches will turn into warnings. I feel like MoCo will probably get advisories, for both parts of the county too(more confident in upper MoCo though, southern MoCo 65% chance). But, we could also get warnings as well. The timeline of this storm is 2 PM Mon - 10 AM Tuesday. Surface temps, for pretty much the whole region will be cold enough to support any wintry precipitation, so that won't be an issue. Now, let's see some models.

Note: All models are either from tropicaltidbits.com or pivotalweather.com. They are very good websites to use when tracking any type of weather, and I would highly recommend using them on your own time.

NAM 3km:

The NAM 3KM shows a very messy storm. It shows it starting as rain/snow, then shows the precipitation types changing so quickly, from snow to a mix, from freezing rain to rain, its a mess. From 9PM Monday to 12 AM Tuesday, the NAM shows a band of heavy snow that moves throughout the county through that time period. That could be the main bulk of the snow accumulation. I am not even gonna try to explain what is happening, its a mess of precipitation switches. The total snowfall from this storm, as the NAM shows is 1-2 inches, which I agree with. However, with sleet, the totals go up drastically. It shows 3-7 inches of snow and sleet for a county, with totals close to a foot, or even OVER a foot in some areas! This is what I am hoping for in terms of snowfall. This would be a boom scenario. However, realistically, I don't think we will get THAT much snow and sleet. But we will see.

GFS:

The GFS shows the storm starting out as rain for the lower quarter, freezing rain for the middle quarter, and snow for the upper quarter. It then shows mostly ice for the county before transitioning over to rain. It shows pretty much no snow for the entire county, in terms of accumulations, but it does show ice. Depending on where you live, the GFS shows a glaze of ice all the way to two tenths. The more northern and eastern you are in the county, the more ice accretion you will get. However, CAD usually lasts for longer than the models show. At this point out, I trust the NAM and HRRR more than the GFS and European, because they are better at predicting close-range conditions. However, the GFS and European models are still important.

Euro:

The European model shows the storm starting as a mix/snow, and then shows it transitioning to rain before it leaves. However, this model skips 6 hours every time it shows the storm moving, so I am pretty sure that the wintry precipitation will fall for a while before turning into rain if this model plays out right. This model shows a dusting - 1 inch of snow in the county, NE areas will see more, SW areas will see less.

HRRR:

This model, in my opinion, handles cold and warm air very well. It is a good model for short-term forecasting. This model shows the storm starting as rain first, and then switching into snow/mix, depending on where you live(northern sees snow, southern sees mix). It keeps switching back and forth, from a mix to snow, and back. The mix will be heavy at times, increasing snow totals. This model doesn't show any rain for the county, other than the initial onset(for the most part). This shows 2-4 inches of snow for our area, which is a nice amount. It doesn't show that much ice accumulation, the more south you are in the county, the more ice you will see, which makes sense(totals range from glaze to around a tenth).

Capital Weather Gang:

The Capital Weather Gang shows 1-3 inches of snow for the upper third of the county and a coating to 1 inch for the rest of the county. The models have been showing more snow than this for some of the areas in the C-1" of snow area, but I can understand why they were conservative and went for the lower totals. 

WBAL 11: 

WBAL 11 shows 1 inch or less, in regards to snow, for most of the county, and for the western side, it doesn't show any snow, just "Ice Accumulation Possible". They lowered the totals for this storm, and I can understand why though, since the main forecast for this storm is mixed precipitation.

National Weather Service Snowfall Map:

This map has increased! It shows 2-3 inches for about all of the county and 3-4 inches for Damascus. That means they are starting to gain more confidence in more snow and ice, which is good. I bet the HRRR and NAM affected this decision!

Same with the snowfall map, the ice accumulation map increased their totals too! The upper part of the county(more on the eastern side) is in the 0.10-0.25 inches of ice, while the rest of the county is in the 0.01-0.10 inches of ice range. This storm is going to be very messy, to say the least. From this map, I expect an advisory for the WHOLE county and maybe even a warning in the upper part of the county? As of 6:10 PM, there have been no alerts issued for MoCo.

I can understand why there aren't many maps for this storm, it's because it is nearly impossible to predict, with temps playing with the freezing mark. This storm requires a nowcast kind of prediction. But what about impacts? Well, it depends on where you live. Any area north and west of MoCo, like Frederick County and the general Shenandoah region, will be hit pretty hard by this storm. There, you could see amounts of ice enough to make power lines fall and create outages. And the snow and sleet doesn't help too. I could see school closures, even in virtual learning, due to power outages. But what about MoCo? Well, the criteria for no school in MoCo, as MCPS has stated, is "countywide power outages". Although it's definitely a possibility in the northern regions, I don't think we will see enough winter precipitation to cause power outages throughout the whole county. And the timing of the storm isn't that great for school closures either. But, during heavy ice accumulation, the crews won't be able to help until the storm is done and over, even in the interior NE and Canada(somewhat). And in the DMV, where we have been snow-starved for a very long time, I don't think the crews will be able to fix it during the storm.  Even after the storm, it will be hard to get power back up to the whole county that fast. So my prediction for school impacts are: A 35% chance of a 2-Hour Delay on Tuesday and a 30% chance of a closure. If conditions start out really bad, we could see a closure on Tuesday, but I am pretty sure we won't get an early release on Monday because that kind of stuff has to be planned out before the storm hits, and that's very difficult to do in this storm. South of MoCo, it's probably just going to be a cold rain for you, but you might see a brief period of a mix.

Thanks for 2000 views!

 Thank you for the 2000 views! It's nice to see an audience who genuinely enjoys my posts and the content of them. I will be taking suggestions for this blog, what do you want me to do? I need some ideas for my blog. Thank you, I will be looking at the runs for midnight right now.

Monday-Tuesday Storm Threat Update

 Well, this is unrelated to the storm I was talking about, but during the 0z run today, the GFS showed a BLIZZARD for the Thursday storm. And then... no blizzard. It still shows snow, but not a blizzard. Models will be very jumpy as we are 6 days out. Anyways, at this point in time, you should prepare for a storm impact on Monday-Tuesday. The storm will start on Monday afternoon and will end on Tuesday morning. This storm is a Cold Air Damming(CAD) situation, which means that there is a dome of cold air on the ground, but in the atmosphere, above the ground, there's warm air. The type of precipitation depends on how deep and strong the cold air is. There are still no ice accumulation/snowfall maps by any of the news stations yet, excluding the National Weather Service, which did make their first map for this storm around yesterday-today. I expect more maps to be made by tomorrow morning/afternoon, or maybe even by this evening. Let's look at some models.

European Model: 

The European model shows this storm starting as moderate-heavy snow(for most of the county), then shows it turning into a mix, and then the storm is done. The European model has actually been trending colder for this storm, but I think we are going to get some wintry mix/freezing rain. But, I will say this, from personal experience: In CAD situations, the cold air lasts longer than what the models show. Overall, the European model shows a more snowy storm than the previous runs.

American(GFS) Model:

The American Model shows the storm starting as rain, then for most of the storm, freezing rain. Some regular rain starts to creep in the lower part of the county as the freezing rain falls in the upper to middle parts of the county, and then the last precipitation the storm drops for about all of the county is regular rain. As I said, the CAD will last for longer than what this model shows, so you might see ice at a time when a model says regular rain for you. And there can be freezing rain, even with temps above freezing, due to surface temperatures, and especially with ice and snow on top of it.

CMC:

The CMC shows a snow to ice/mix to rain system for all of the county. There's not much else to say here, other than that the CAD will hold longer than this model shows. This model shows more rain than all of the other precip types. 

Now, let's look at the NWS maps!

This map from the NWS shows a wintry mix for all of our county, but this isnt specific. They also said that the wintry mix will likely go further south than what this map shows, which I agree with. This map doesn't include all of the places that will get a mix because at this point, it is in their best interest to show places that almost has a guaranteed chance to see a wintry mix.

This is the snowfall map for this storm that the NWS shows. It shows 1-2 inches for pretty much all of the county, with the extreme southern parts getting less than an inch(plus spotty areas in the county), and 2-3 inches for some of the northeastern parts of our county. I agree with this map more because the NWS is counting in for more of that wintry mix.

This is the ice accumulation map for this storm. The lower half of the county gets no ice, while the upper half gets 0.1-0.25 inches of ice, with some spotty 0.01-0.10 inches of ice mixed in. The NWS is counting for wintry mix and ice in their forecast, and I think, in terms of forecasting perspective, is the right thing to do. The more north you live, the higher the ice and snow totals will be.

I didn't show any snow or ice totals for the models because news stations' maps usually start to come out at this period, and they have a combination of all 3 models, plus more models than I have access to right now, plus with some personal instinct. But I want to talk a little bit about the Thursday storm because it looks more promising. No maps or anything though. The GFS put HUGE totals for the Thursday storm, amounts such as 15-20+ inches of snow, with it being a blizzard too. And during the 12z run, the amounts went down drastically. This jumpiness was expected this far out though. But, it's a step in the right direction. The European model now shows at least some snow for our area for this storm, which means that it is adjusting to the other models. This storm has a good shot, and the track + pattern + system for this storm is better than the storm on Monday. The NWS has put down a slight winter storm threat for this storm(Wed-Fri), but for the entire region, the DC and Baltimore NWS forecasts for. I don't think we will see a crazy, "Snowzilla" like storm for Thursday, but it could easily put down a good amount, to end the snow drought. They have all come to an agreement of some snow though, 2-4 inches. We are still very far out though, which means that we could see nothing or a significant snowstorm. We will see...

2 Storm Threats in One Week + Mon-Tue Storm Update

So you know how I said we will see at least a brief period of cold weather? Well, we have 2 storm chances, and the second one looks much more impressive than the first one. The first one is the storm on Monday-Tuesday and the second one falls around Thursday - Friday. The first storm is now less than 100 hours away, so let's talk about it! No news forecasts, at least that I am aware of, have released any maps, so instead, we will be looking at models!

FIRST STORM(MONDAY TO TUESDAY):

GFS(American Model):

As you can see, this storm turned from a snow threat, into an ice threat. The GFS is showing mostly ice for our county, with some rain at the end. We could see backend or frontend snow, but it won't be anything that's enough to be the main concern. This storm could still change, but at this point, the trend is that we the cold air won't push far enough south for us to get an all snow event, at least for this storm.

GEM(Canadian Model, aka CMC):

This model shows the precip starting out as snow and then transitioning to ice/wintry mix. I don't agree with this model that much, because I feel like its putting too much snow for our area. The biggest concern is defintely the ice, but this could happen too. We could start as snow but the precip should mostly be ice/ a mix.

European Model: 

The European model has almost all of the county starting out as a mix, then it turns into more ice. I feel like this model is what is most likely to happen (European has the most accurate track record), but I also feel like some rain could easily overtake it.

Now for the amounts. The only model that I have the exact ice accumulation amounts for is the GFS, but for the other models, I will just show total accumulated precipitation.

Canadian Model(GEM):

This model shows 0.5-0.75 inches of accumulating precipitation in total(not one certain amount). And if most of it falls as freezing rain, we could have a bit of a problem. We could have an ice storm, which is much worse than a snowstorm. We could lose power for an extended period of time, which will not be good. I will tell what this means for schools later in this post. However, this does include snow, but if we do some simple math, we can find out how much of it is ice. Assuming a 10:1 ratio, the GEM shows around 0.2 - 0.45 inches of ice. Yikes...

European Model(Euro): 

The European model doesn't show any snow falling in this storm, so almost all of it should just be ice(sleet included as well). That's 0.6-0.85 inches of ice. That's a significant ice storm, and is very dangerous. I wouldn't be surprised if there's a state of emergency for this level of ice. However, we probably will see some back/frontend snow or rain in this, but thats still a lot of ice.

GFS:

The GFS shows 0.45-0.55 inches of ice. That's already enough to cause major damage to infrastructure. However, this is total accumulated ice(precip for all of the other models), so chances are we won't be seeing this much at one time. If models keep this up, this is looking like a dangerous ice event.

The National Weather shows an enhanced threat for the upper half of the county, while the lower half is in a "slight" winter weather threat.

IMPACTS

So what impacts does this mean for school systems? Well, if you like no school, this actually looks good for no school, because ice storms, especially to the extent these models are showing, cut out the power and cause state-wide outages for an extended period of time. Crews won't be able to work on the power lines until the storm system is out of our region. And MCPS said that the only way schools would be able to close during virtual learning would be if there were countywide power outages. Well, there you have your countywide outages! Everything in Maryland would be shutdown, with the exception of essential services. I assume most people in Montogomery County don't have access to secondary power/generators, so it would probably shut down schools if the ice storm happened.

 

SECOND STORM(THURSDAY-FRIDAY):

This storm seems much more impressive because there will be an abundance of cold air in this system. This is the chance for an all snow event. But, at the same time, this is an all or nothing kind of storm. Either we get a lot of snow or just nothing. However, models are shaky about this storm. 

GFS:

The GFS does show a little bit of snow for our county, but the main snow that would bring us a good snowfall amount... is to the south. However, it's a week out, so many things will change. 

Euro:

The Euro just shows some snow showers/flurries for this storm, which is even worse than the GFS. The "bullseye" area for this storm won't get that much snow either.

CMC:

The CMC shows heavier snow for this storm than the other models. However, we still aren't in the bullseye of this storm. It seems to be south at the moment. However, stay hopeful. We are still a week out, and this can easily change. We have all the ingredients we need for this one.

I do not believe in showing snow totals for a storm that is over 5 days away, because I don't want to overhype everyone into believing we are getting a snowstorm, because when it disappears and nothing happens, people are confused. 

Summary:

The summary for this post is that there will be a storm that will be moving in on Monday-Tuesday, and it will mostly be an ice storm, and there will be a second storm on Thursday-Friday that looks much more promising for an all snow event.

New Storm Threat for the 25-26th!

 As you read the title, there's another storm threat, here we go again. However, this storm will take place during a below normal temperature period, as you might have heard of in my last post. The colder air will allow for bigger snowstorms. It's also inauguration day, during the time period when I wrote this. If you are reading this after the afternoon of today, happy inauguration day! Anyways, let's look at the models.

This image, from a tweet from Mike Thomas, shows the European model bringing heavy snow for all of Maryland during 3:30 AM. If this scenario actually happened, this would be a very good one, for snow lovers, as you will see down by the image below.

This shows our area getting a lot of snow, with over a foot of snow possible in areas! It's pretty crazy, the highest snow totals will be in eastern WV. The more west you are in this storm, the more snow you will receive. Now let's look at the American model!

The American model shows less snow for our area, unfortunately. This is a snapshot of what the GFS thinks it would look like at 10AM on Tuesday. The American model only shows us getting to about an inch, maybe take or give one. There's more, however. 

The National Weather Service shows a slight threat for not just our entire county, but for the entire region of the DMV. The reason it's a slight threat is that the threat is far out, and we don't have a good idea of how much it is going to impact the region. If the models keep this threat up, I would expect the slight threat to turn into an "Enhanced" one, a "Moderate" one, or maybe even a "High" threat. It's very possible.

This is just not a "one model shows something, the others don't" scenario. The models are in agreement, and that's surprising, especially this far out. However, because this storm is for the DMV, don't get your hopes up. Because the next day, it could be gone. Completely. My hopes are more up because of the favorable cold air and the fact that most models agree from this point out. Overnight models have held up as well. It's a week away though. So don't hold your breath.

It's going to get much colder...

 As you might have heard already, we are in a favorable pattern for snow. However, we still haven't gotten any snow at all, even in the favorable pattern for snow. However, this means that if we get a good potential for a good storm, the chances of it happening increase. But, as you read by the title, its going to get colder. 

As you can see by the image above, there is indeed going to be colder temperatures in the next 6-10 days, and chances are leaning towards being colder than normal. We have sufficient cold air for the time period of 1-22-2021 to 1-26-2021. This means that any precip potential could easily give us a snowstorm. But that's not all.

Now this one shows a much stronger and higher chance for cold air! This means that any precipitation in the period of 01-24-2021 to 01-30-2021 is probably going to be snow. Expect temperatures in this period to be much, much colder than the temperatures we have now. But there's even more. 

Now, this thing really puts a good scenario for snow in our area. Why? Precipitation(not snow, just all precipitation in general), is supposed to be above average during the time period of 01-24-2021 to 01-30-2021. With the much colder air, this could easily bring us some snow. For the first image I showed you, the precipitation is supposed to be barely below average for half of the county(eastern side). However, we can still get some good snowstorms in that period too. 

This image from Justin Berk, a meteorologist, shows that after Friday the 22nd, the temperatures start to plunge and become colder. But, it's not just one cold push. The cold is going to be sustained, from the last part of this month to the beginning of February. That is good for snow, because it gives a good period of time for some snow to fall.

In conclusion, we will start to see colder temperatures after this week, and the cold air will be sustained, while we are in a favorable pattern for snow, giving us a good chance for snowstorms. The likeliest time for significant snowstorms is between 01-24-2021 to 0-30-2021, as we get more data.