Fri-Sat Snow Map and NowCast

6:55 PM:

Snow starting to pick up here and stayed for a while before lightening a bit again. Looks like snow bands are going to struggle to come north, totals on the lower end of the ranges are expected now.

5:45 PM:
I now expect 1-3" for the general DC area, including MoCo. I think the 2-4" accumulations would be a good amount further SE than in my forecast. Southern MD is still on track on my forecast so far. We will see how the evening goes.

5:25 PM:

Moderate snow coming down here, stickage on grassy surfaces. Looks pretty good so far. After sunrise, temps will drop and snow will pick up, allowing for more stickage. Brunt of the storm is NOT over yet.

Sorry I didnt have any time to make a post, I'll just put my final call here. Accumulation should start to ramp up after sunset, and thats when snow will start to pickup. Generally expecting widespread 1-4" of snow throughout the region. I'll have an update at 5:30.

test

 heehee

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 Call Snow & Ice Maps and Nowcast

 

These are my final call snow and ice maps. Almost nothing has changed for the snow map, but the ice map has took a change for the good: The 0.1-0.25"+ zone is now gone, and has been replaced with the 0.01-0.1"+ ice zone. Most people will only see up to a tenth of an inch of ice, but the plus is there for the mountains who will have cold air for longer, allowing for longer ice accumulations. Also some localized areas may see amounts just above a tenth of an inch. Cold air was undermodeled and WAA was overmodeled on high res models if you look at radar. This could mean a longer time period of snow, and just in general wintry precipitation. Surfaces will be below freezing for a while even when temps start to rise above freezing.

MLK Weekend Storm - What to expect

Good afternoon everyone! We have a winter storm threat to track tomorrow and Monday morning. This threat is looking more like an ice threat instead of a snow threat; but if you live north and west of I-95 you will still see some snow accumulation for this storm. Unless you're far north and west(along and west of I-81), you probably won't see an optimal amount of snow - if you like snow. This storm takes an inland track - so being even a little bit more west can make a difference. When the snow starts, it will be heavy, with rates 1-3" per hour. When it snows, it will thump. Wind gusts up to 45 MPH are possible with this storm, creating the possibility of downed trees and spotty power outages, especially when ice starts to take over the snow. I would recommend to stay off of the roads(if NW of I-95) on Sunday-Monday, as the snow with ice makes roads very slippery and impassible at times. There is a very cold airmass in place for the storm, so ice and snow will stick longer to untreated surfaces. Please note that freezing rain can happen even above freezing, if surface temps and wet bulb are still <32. There is a winter weather advisory for all of MoCo, with 1-3" expected and up to 0.1" of ice. Just north of us is in a winter storm warning, for 2-4" of snow and 0.1-0.3" of ice.

NAM12KM:

Note: at the time where it shows pink for our area(7 PM), I looked at a sounding for Germantown/Gaithersburg and it would seem as if it would be sleet, rather than freezing rain. Still, you can see everyone starts off as snow, and then the warm nose comes in, turning into sleet, then freezing rain, and eventually, when the CAD breaks, cold rain. 

 

 

Ice total and snow total maps, pretty self explanatory.

NAM3KM:

 

The NAM high res shows everyone starting out as snow, then going to ice, and then going to plain rain. The NAM 3KM also shows some backend snow, which is interesting. However, it seems to be light snow, and probably wouldn't amount to much. A lot of the rain will wash all of the snow away, so even if 3" fell, it wouldn't look like it.

 

 

The reason why the NAM 3km shows a lot of ice is because of strong southeasterly upper level winds, forcing warm air into the atmosphere and creating a warm nose that gets more dense as time goes on. Eventually, the cold air at the surface breaks, and areas east of I-81 switch to cold rain.

 

 One other thing I want to talk about is the wind gusts. At this time(8P Sunday), freezing rain is falling all throughout the region. With the strong wind gusts(40-50 MPH wind gusts), isolated power outages and downed trees is likely. I would recommend everyone north and west of I-95 to get ready to deal with some time w/o power, just in case.

*Editors Note: While I was writing this, the 18z NAMs came out, all of the models shown are from the 12z suite

My snow and ice forecast:

(I apologize for very low quality maps, Blogger won't let me put high quality pictures) 

My next update for these maps will be tomorrow morning, after 12z mesoscale runs come in. I'm going bullish with my forecast because I think there will be heavy enough rates for a large enough area to get 2-4" before the changeover to sleet, freezing rain, and then cold rain. I think the NAM is too bullish on the warm air coming in very quickly and changing over to rain, so I didn't use the NAM that much in my forecast. Other models look pretty good for our region in terms of snow, such as the Euro, GFS, and HRRR. My final call WILL be tomorrow morning, after 12z HRRR, and both NAMs come in.

To conclude, I expect 2-4" of snow(possibly more in localized areas) for Northern MoCo and 1-3" for Southern MoCo. For ice, I expect 0.1-0.25" of ice for the general area, with possibly more in localized areas. Timing onset will be in the afternoon, at 1-3 PM. This will be a high impact storm, especially west of I-81, and also for NW of I-95, not just for snow, but for ice. I am very concerned about the ice threat, since CAD is usually undermodeled, especially on global models, and the ice combined with the strong wind gusts could create widespread power outages and downed trees. I'll have a quick update tomorrow, and then I'll do a nowcast.

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.

Big Snowstorm for DC area?(January 3rd Snow Threat)

This is the first post of 2022! This winter so far has been devoid of any snow, and most areas haven't even seen a dusting yet, apart places near the Mason-Dixon snow. However, as a new year's gift, we have a good chance of our area seeing any type of snow. In the past 24 hours, models have been trended towards our area getting more snow. My snow forecast, and snowflake prediction will come tomorrow, as small changes could lead to us getting a lot of snow, and us getting little to nothing. The models have been trending northwest with this storm. Usually, this is not good for us, but in this case, this actually benefits us, as the main concern of this storm was that it was going to go too south and just miss us. The bullseye of this storm, previously in southern VA, is now trending to be our area. Pretty much every weather model is going northwest. This is because the strengthening of the Atlantic ridge, and the weakening of the northern piece, allowing the storm to go further north. The main shortwave responsible for our storm has already been sampled, and it causes the storm to be slower, which is favorable for more snow. I won't make any guarantees yet. This one might be a major one for the DC Area.

 

As of now, the models have the heaviest snow south of DMV. The GFS took a considerable tick northwest, showing heavy snow for southern MD, and still some moderate snow for Montgomery County. Our county is the gradient, and any counties north of MoCo gets much less, but that shouldn't be an issue for too long as the storm goes northwest. Still, I think the highest totals will be in southern MD area.

 

As you can see, quite the gradient is in MoCo. Northern MoCo gets 3-6" in this run, while southern MoCo gets 6-9". I don't think there will be that much snow accumulation, even in Southern MD. Kuchera is the most accurate snowfall total parameter, taking in surface and upper-air temps, with precipitation rates, and much more. We will see tomorrow.

 

I would usually show the NAM, but it is the weirdest solution. If you look at the vorticity, the northern piece trended NORTH, and weaker, so by all standards it should have went northwest, right? It went southeast instead. If you want to see the vorticity, you can look on tidbits/pivotalweather/cod, I won't show it here to confuse people more. 

GFS Ensembles:

These are the ensemble members, and practically all of them show snow for some part of MoCo.

The ensembles support the GFS, but it is more realistic with totals(this is 10:1, I would assume kuchera has more snow). 1-5 inches for our county, with the most snow being in the southern part of our county.

HRRR:

Although southern areas start out as mix/rain, they quickly turn over to moderate snow. The reason they are getting more than Frederick, for example is because they have much more moisture(QPF) to work with. Even though there is more cold air in Frederick, the total precipitation there is much less of that of southern MD's. 

 

This snowfall solution is very similar to the RAP's, and is heavily trending northwest. Our county is the gradient so far, not for long as it trends northwest. 2-8 inches, with the most being SE MoCo, same as all of the other models. 

 

RAP:

The RAP is practically the same as the HRRR, except that it is more aggressive with northern areas getting much less snow(1-6 inches for Montgomery County, sadly I don't have DMV area zoom with RAP). There's not much to explain here.

 

As for school closings, if the higher totals of this storm shift northwest enough to make it to Montgomery County, I am almost certain MoCo will close for at least one day. 6-10" will definitely be more than enough to close schools.

To conclude, all of the models are showing favorable snow for us, and the DC area may be the bullseye of this storm. I won't make any guarantees, but as of now, its looking amazing for snow, especially if you live south and east of DC. This could potentially be the most snow we've seen since January 2019! I'll update everyone tomorrow, and make my snow forecast + snowflake prediction.