Archival of Blogger and Move To Substack

Hello everyone, I'm making this post as a formal gesture that I have fully moved to Substack and will not be using this website anymore. It will still be up for archival purposes and for reference, but it will no longer be updated. The reason for this move is that I found it much easier to work with Substack in terms of the text editor, but mainly with formatting images. Posting images on Blogger is usually of much lower quality due to overcompression, and it can sometimes be a pain to adjust everything. I don't have to deal with that on Substack, and it generally looks nicer and is easier to use. That being said, I might update my snowfall tracker with data from 2023-2025 if I have some spare time. Most of my work will be through the avenues of my personal substack and MoCoClosures, an organization dedicated to predicting weather impact on school operations, but we do more than that. I will be posting my work on a seasonal forecast (along with a few other forecasters) through MoCoClosures. Thank you for reading my posts over these several years, and I hope to see you over on MoCoClosures and my personal substack. 

My Substack: https://darkshark.substack.com/

My Twitter: https://twitter.com/shark_wx

MoCoClosures Substack: https://mococlosures.substack.com/

MoCoClosures Instagram: https://www.instagram.com/mococlosures/

2/13 Rain to Snow Event for Morning Commute

This will be a quicker post since I only have a little time today. But we went from a generally all-rain storm to potentially quick heavy snow in less than 24 hours. The South trends on modeling with this short of a lead time are quite remarkable, and I'm not sure if I've seen anything like this, at least recently.

 A dynamic system will be approaching from the TN valley, bringing precipitation to the mid-Atlantic and Northeast, a lot of which will be snow. Winter weather advisories are up for those NW of 95 and N of I66. 

We will start as rain, but likely switch over to snow and see accumulations in these areas. For us, we get cold enough to snow from dynamic cooling; this system will be very dynamic. It depends on rates, and the boom/bust scenarios are equally likely. The bust scenario would be that we do not get heavy rates and little to no accumulation; the boom is that we get heavy rates for a few hours. Despite marginal temps(33-34), heavy snow rates will accumulate, even on sidewalks/roads if heavy enough. This storm will be more of a latitude and elevation-based storm rather than longitude. That's why central/northern MD is more favored in this setup. Even with heavy rates, your ratios will be low and it will be a wet snow.

Precip will likely onset between 5-8 AM, with central MD expected to be all snow by 7-8 AM. Guidance is indicating heavy precip rates, which timed with the morning commute will make it hazardous. It's not more so about the actual amounts, but the heavy rates expected and the timing are perfect to impact the commute. This storm has trended so far south that Maryland gets in on the main snow shield; and not just the backend. Our storm's preformance will depend on these rates. 

There is the potential for 1-3 hours of 1-2"+ rates during the morning commute. With these rates, it will accumulate, even on side roads and paved surfaces. Heavy rates always beat marginal temperatures or any other factor. The previous rain will also make pretreatment impossible. The heaviest rates will likely be just after the switchover(when dynamics are the most favorable), with thundersnow possibilities being hinted by guidance. We won't know what this storm will do until we get there; it is fully dependent on the level and location of banding.

Snow Map + School Predictions:

HREF forecast for the next 24 hours; 2-4" NW of 95 and N of 66 with 4-6" for 70 and north

This is my snow forecast for the event; I think there should generally be at least a solid inch for N of 66; further south should stay under an inch. 3-6" for elevated areas near the MD line and of course, the mountains look like a good call. especially with the recent trends. I would not be surprised at all of the warnings were issued last minute for those regions. The plus in the 1-3 zone is mainly for higher elevated areas. This is a very difficult forecast, with an equal chance for a boom and bust. 1-3" is just in the middle zone and I feel like it will either be a bust/boom. Either way, the morning commute is looking awful, and there will be impacts. As for school impacts...

Prediction: 3 Snowflakes
I'd expect many school impacts, with widespread delays and even closures, especially for counties in the 3-6" zone. The timing of this is perfect to at the very least delay. There is also a 50/50 chance for a closure depending on how long the rates last, and how intense they get. If the rates last for long enough, schools will be forced to close, and there will be enough accumulation on the roads. With the current forecast in place. and the rates guidance is showing,  there is really no way schools can open on time tomorrow.

Overall, a nice sneaky event. I think this is going to surprise a lot of people; enjoy the snow!

12/10/2023 Accumulating Snow Event NW of I95

 Guidance has converged on an anafrontal system with a secondary low that provides the opportunity to see some snow, as moisture is thrown from the secondary low into the cold sector. Thus, this gives us to potential to see snow falling, with (light) accumulation prospects NW of 95.

SYNOPSIS:

A shortwave, which has already moved through the country and continues to do so has a cold front ahead of it and northern piece energy. The trough axis is delayed behind the front, so we set up an anafrontal event(not typical).

 This system overall is very dynamic and should have good PVA in front of it which induces cyclogenesis(intensification of the storm) and moisture advection. Temp gradient is also quite large, with the airmass behind the cold front being Canadian and the airmass in front of it being subtropical.

We also have a dual jet setup associated with this which pops a secondary low when the trough becomes negatively tilted, in the Carolinas. This directs winds and moisture return NW.

The large temp gradient should allow for frontogensis forcing, which will make precip rates extremely high. CAA driven snow will occur in the overnight hours after midnight for most people as temps drop.

One thing to note about this system is that surface temps are extremely marginal, but the rest of the atmosphere is <0C, allowing for it to snow. These heavy precip rates will allow for greater dynamic cooling and a saturated column.

    

OBSERVATIONS:
We are now less than 12 hours away from snow, and the use of models is useless. As of 23z(6P EST), the trough is netural-slightly negatively tilted over MS/AL.

This is ahead of schedule, as it was supposed to be this way at 7-8 PM. This will have better implications downstream as a earlier negative tilt will allow for cold air to fill in faster during the snow, and the secondary low to pop more/quicker in a favorable location.

The cold front was also ahead of schedule, and stronger than modeled, passing the BR by 515-530 PM. 

Temps are dropping quite quickly behind the front, with some station reporting degree drops every 4-5 minutes. Although it is worth noting that sfc temps are warmer than on NAM, they are colder than on HRRR(behind the front), and it just initalized at 22z

The rate temps are dropping behind the CF, catching up to NAMs temps wouldnt take too long either. It's running too warm for some parts of nova at 0z anyways. We'll see though, eitherway temp wise we look good.

And now we look at the radar, we are starting to see the backside precip fill in and amplify. It looks very good with convection off the Carolinas. This system is absolutely juiced, and is exceeding expectatations. 

So overall, it might be safe to say that this event is going slightly better than expectations. Observations look great so far and is expected to continue into the event. 

Overall:

Overall, despite uptrends, the general picture is the same: accumulating snow for NW of 95, mainly in higher elevations. Temps will be very marginal(32-36), but we might push colder during heavy bands due to CAA. That being said, we need heavy snow rates to stick. Otherwise, it will not stick; moderate or below will not do it. Mesoscale banding features are too hard to resolve at this range, so there is no really saying where it will be, but if I had to guess it would be somewhere around here(NW of the fall line): 

As for snowfall, there will be an extremely sharp cutoff on I95. I have trouble thinking anyone inside or east of the beltway will see more than just white rain, with little to no accumulation. Elevation is just too bad there to get anything substantial. Temps will be too marginal there for anything. Even further NW, temps will remain 32-36 for most of the storm, with the exception of lower temps 1000'+ or in the bullseye areas. The reason I'm even going this bullish on accumulations is because of the puking snow rates that will set up somewhere that will stick to the ground despite temps. The rates cannot be moderate or light, they have to be heavy, but we know it will set up somewhere,, and that area should see nice accumulations. Having heavy wind should also help blow the snow around and even help with stickage as wind removes latent heat release; it would help us more than hurt us. This, along w/ heavy rates will make for low visibillity conditions. 

As of N of the fall line, I gave the highest amounts to areas 700'+ elevation and west of I81. The bullseye for this storm overall will be the Blue Ridge and the Apps, as expected. Locally, the bullseye is probably the Parrs Ridge if I'm betting.  In the Parrs ridge, there could be a spot of over 3"+ if everything goes right. I went extra bullish based on new data we have, but this could very well bust. I feel like this is a boom/bust type setup; either we do really well with banding and get puking snow for hours accumulating to over an inch, or we generally stay mostly rain with no acccumulation even if it snows. Ratios will be very low; likely 4:1-7:1 depending on your location.

And as for school impacts, models have trended earlier with the event, generally wrapping snow 5-7A through the region, but before that it will be absolutely puking, along with strong winds as the low intensifies and moves NE. The snow will melt extremely fast afterwards, but I still think theres a chance we could pull off a delay. I'll go 2 snowflakes(50% delay) for this event, if band is a bit later then we'll probably delay. If we can get a WWA in place we probably delay, but it can go either way. Accumulations will mostly be on grassy surfaces, but depending on rates, could be on some side roads and sidewalks. Overall, this event should lock in Dec measurable snow for most areas, and should be really nice to see. 

Snowflake Prediction for Friday

My snowflake prediction for Friday is 2 snowflakes. Exact percentages are 55% delay, and a 10% chance for closure. The reason I'm leaning towards a delay is because the HRRR is now showing a lot more additional ice on top of what we already have throughout the night. Although temps do rise above freezing, there won't be enough time for it to melt for a full day. I think there won't be a closure because temps will rise very quickly above freezing and melt all of the ice. Even though the ice won't accumulate that much on sidewalks and streets, there will be some slick spots in areas with the simulation the HRRR is showing, at the very least. Some streets and sidewalks could be completely covered in ice, especially in areas like Damascus. The storm looks to be overpreforming a bit right now. HRRR isn't picking up on the freezing drizzle that is happening right now too. Temps dont get above freezing until 7 am on the HRRR for some parts of the county. Because of these reasons, I am confident in a delay but not in a closure. Remember: what the HRRR shows is ADDITIONAL ice. The WWA goes until 10 am for Northern MoCo.

MCPS going virtual for some snow days now -- new rating system

Unfortunately, the thing that I feared the most to snow days happened: MCPS is now going to go virtual for most snow days. However, there is a catch, thankfully. They will consider going virtual for inclement weather. This means that there will be some inclement weather days that will have a traditional snow day rather than a virtual learning. On a virtual learning inclement weather day, the schedule will operate on a 2 hour delay -- except it's on Zoom. Delays and early-releases will still operate as normal.

I will still be posting about weather that impacts the DC area, and still make school predictions about what MCPS will do, no matter what happens to snow days. 

I have updated the snowflake rating system and added a new rating system: 

The CHROMEBOOK rating system

The chromebook rating system is used to predict whether or not there will be a traditional snow day or a virtual learning day if MCPS needs to close in-person school for inclement weather. It is still undetermined what MCPS goes virtual for -- and what MCPS goes traditional snow day for. I assume that if there is a lot of snow -- especially wet, they will call a traditional snow day. It is still undetermined and no one knows what they will do what for since we havent gotten a snow day with this new rule in effect. 

Here is the new Chromebook rating system:

Most Likely Virtual Learning(if closure in-person):

1 Chromebook: Most Likely Virtual Learning

2 Chromebooks: 35% Chance of Traditional Snow Day

Most Likely Traditional Snow Day(if closure in-person):

3 Chromebooks: 55% Chance of Traditional Snow Day

4 Chromebooks: 75% Chance of Traditional Snow Day

5 Chromebooks: Most Likely Traditional Snow Day

 

And for weather news, there is a storm signal around February 14th(Valentine's Day) that I will be watching. It is still too far out to discuss anything about the storm -- at this point in time we just want to see if the pattern supports it. That is all for this post.

 

 

 

Delay possible tmrw

Based on the flash freeze that's going to happen overnight, and some side roads still being messy, I'm going to say a 45% chance of a delay(around 2 snowflakes) as of now for tomorrow. Side roads in many areas are still messy as the rain did not wash all of the slush away. Let's not forget about the flash freeze that will happen tonight, wet roads will quickly turn to ice. As of now I'm not leaning towards a delay, but it's more than possible.

Final Forecast Jan 6-7 Storm

Good evening everyone! The models have trended for lower totals and lower QPF, however this event still shouldn't be too bad, with 2-4" still expected. I'll only be showing 3 short/medium-range models(NAM, NAM NEST, and HRRR), my snow forecast, the NWS forecast, and my snowflake prediction.

NAM NEST:

 

The NAM NEST(higher-res version of NAM) shows a heavy band hitting a lot of the area between 1-3 AM. NAM 3km actually looks pretty accurate to what we are seeing on radar, except that the fact that radar has the storm a bit more amped. Anyways, shows widespread 2-4", with some localized areas getting higher than that.

NAM:

The NAM shows a pretty decent solution for this storm, with 3-5" north and west of DC, and 1-3" DC and south. It shows a moderate-heavy band that hits many of the DMV, with the highest totals being north and west.

 

HRRR:

 

The HRRR shows light-moderate snow for most of the storm, with a moderate-heavy band moving through between 1-3 AM. Compared to both of the NAMs, this model is more conservative for the snow totals, with 1-3" for most of the region(some areas 2-4"). 

NWS Snow Forecast(forecasted, and high-end all in respective order):

My Snow Forecast:

This is my snow forecast. Latest guidance shows heavier snowfall(2-4") being reserved to north and west of DC. Most of MoCo is in the 2-4" area, except for very southern MoCo. The reason I went 1-3" was because of dry slotting, a common thing which happens in Miller Bs such as this one. The initial low pressure weakens, and the new one forms. When this happens, it allows dry air to come in, which would reduce the snow totals from this storm. Hence the 1-3" area was expanded. If you live in Northern MoCo, and any areas N & W of it, I think you should be fine for the dry slotting. Will have to watch closely.

My Snowflake Prediction: 

3 snowflakes

55% chance of a closure, and a 75% chance of a delay

The reason why I think we have a good chance of closing is because of the temperature, and winds tomorrow. Temperatures will not rise above freezing for almost all of the county tomorrow, meaning that whatever stuck will stay there. Additionally, it is supposed to be windy tomorrow, and a fluffy snow is expected, meaning that blowing snow is another hazard that needs to be worried about. Even though totals are more on the lighter side, it will be more than cold enough for the snow to immediately start sticking to untreated surfaces. If we get the high-end amounts, I am more than confident in a closing. As of now, I am a bit unsure on whether to lean towards a delay, or a full-on closing. I will change the chances as new information comes in. Needless to say, I am pretty sure there will at least be a delay.

Snow Threat Jan 6th Night - Jan 7th Morning

Good evening everyone! The NWS has put a winter weather advisory for the entire region, with 2-4" expected, and up to 5-6" in isolated areas. The usual trend of north and west getting more snow is back. Models have been all over the place with this event, and especially with the low placement. The snow will arrive tomorrow night, and there will be enough to shovel and plow. There won't be as much as 1/3 gave to SoMD, but there will still be a moderate amount of snow. Heaviest snow will be around midnight for Northern MoCo, with rates up to around an inch per hour. Where the frontogensis bands setup is where the heaviest snow is going to be. According to Sterling's AFD a short term winter storm warning may be required if a band persists over a specific localized area. Temps before the event will be much colder than 1/3, and it will be below freezing the entire time the snow is falling, so snow will have no problem sticking on untreated surfaces. This snow will be easier to shovel as it is a more dry, fluffy type of snow.

GFS:

 

This is the model that shows a more southern solution. 18z run had a more amped storm with less confluence, allowing the storm to go more a bit more NW. Still shows 1-3/2-4" for most of the region with 4-6" in SoMD.

 

NAM(High-Res, 3km):

 

The NAM is a more northern solution, and shows more snow for our area in general, 3-6" for most areas north of DC and 2-4" south. The influence of dry air for the northern part of our region may cut down on totals. That will be the more difficult part, finding out where the dry air sets up. 

NWS Forecast:

 

(sorry for low quality image, blogger wouldn't let me adjust the size of the high-quality image)

My Snow Forecast:

 

 

Snowflake Prediction: 3 Snowflakes

With temperatures being cold enough the whole day to support snow(<32 for most of the county), and there being 2-4" during the start of the rush hour, would pretty much confirm a delay. Additionally, if the heavier bands setup over our county, giving some areas warning level snow, that would take much longer to cleanup and cause more issues. The new superintendent seems to be more lenient with giving out snow days, at least so far, which is good. There is a pretty decent chance for schools to be closed tomorrow, and depending on how models go tomorrow, that chance may increase or decrease.

First Significant Snowfall of the Season

 Update: All schools in MoCo have closed for tomorrow

I have a Twitter account, follow for more weather related news: https://twitter.com/shark_wx

 

Overnight, models have trended towards the better for snow lovers. The model runs have only been getting better and better for snow. All of the models have either trended NW, or stayed in the same place. Also, every model has been trending more amped(powerful), and reserved(slower), which means that when we get snow, its gonna be dumped on us. The storm on radar also looks more amped and NW compared to what the models were showing, which is very good. Southern MoCo is in a WSW(3-7" expected), and Northern MoCo is in a WWA(2-4" expected). Near blizzard conditions are possible with this storm. If NW trend continues, Northern MoCo will be in the WSW too. Snow rates between 5a - 11a tomorrow are the heaviest, with rates being 1-3", and with <32 temps, it will not take long for the morning commute to descend into chaos. I'll be making my snowflake prediction for school closings, and my snow forecast!

Euro:

 Euro shows 8-10" of snow for MoCo, and it's solution is similar to the 21z RAP.z

 

The Euro ensemble has >90% for almost all of MoCo to see 3+ inches of snow. The extreme northern part of MoCo has a 80-90% chance, which is still VERY high.

SREF:

This is the SREF mean. It shows 6-12 inches for MoCo and south. At the start of the storm, it will take a while for the ground to cool, but oh it will cool very fast once it really starts to snow. This isn't kuchera, so it will be inaccurate. At the start, snow ratio will be less than 10:1, but when the heavy snow starts to pick up, and temps start to drop, the ratio will be more than 10:1. Overall, the SREF mean shows a significant snowfall for our area. 

NAM:

(Credit: to dollar monkey#6663 for telling me this)

I don't trust the snow amounts and the ptype map on the NAM, but my friend saw something on vorticity that was really interesting. The area that was circled could potentially have a heavy snow band in that area, which would increase totals. Bands always form north of what is modeled, and this one looks to do just that. There is a tail at 700 mb vorticity, and that usually means that north of it gets a heavy snow band. Hence, I think that a heavy snow band will form in this area. The first image is an alternative scenario where the band sets up further south, and the third image is a scenario where it sets up further north. I have a more confidence for the third image(FGEN at 700mb supports this, second image), and the band will set up in the DC metro region. This was something interesting I found on the NAM 12km.

 

GRAF:

 

This is the GRAF model. I don't have access to this model, but I was able to find it online. It shows 6-12 inches for almost all of our region, including extreme southern Frederick county and south of that. It shows 12-18" of snow for parts of eastern MD and DE, which might be a little too extreme. I am not sure how well this model does, but I heard that it does really good with these types of events. This shows a widespread significant snowstorm for the DMV.

RAP: 

 

This is the RAP. It shows a widespread 6-12", with SoMD getting the highest totals. MoCo gets 8-10" of snow, which is a VERY substantial amount. I would say that this wouldn't be as extreme, but the storm as of 5:52 PM looks much more stronger and amped on radar, with more moisture, so this could indeed verify.

My Snow Forecast:

 

This is my second call for snowfall for the January 3rd event! It's pretty self explanatory what the totals are, so I'll go over why I made it like this. I feel like this storm will over perform. On radar right now, the storm is more north, and is much more amped than high-res models were showing, which is a very good sign for this storm to boom. I was talking about the possible location on where the heavy band sets up, and that would increase snow totals significantly due to a good thump. Because of models overall trending for the better, and the observed storm is doing better than what was expected, I made the snow totals more widespread and increased them. DC and south is going to receive 6-12" in my opinion because of the heavy thump of snow and possible banding forming there. I think 5-9"+ for central and semi-northern MD(MoCo) because of the storm going a tad bit north with much more moisture. There is a possibility that the 5-9 area could see more than 9 in localized spots because of heavy banding moving north. Snow rates will be extremely heavy with this storm, and will overtake ground temperatures quickly. It will start off as rain before quickly turning into snow.

 

As for the snowflake prediction: 4.5 Snowflakes

 

I am very confident in schools closing for this system. 1-3" rate snowfall during the rush hour is a recipe for disaster. Crew won't have enough time to fully treat the roads, and the initial rain will wash off some of the salt and make it less effective. Winds are also going to be very gusty, further creating a visibility problem. I just cannot see how schools will open, even on a 2 hour delay.