Prepare to qualify...

Storm day is here and it's going to be a big one. I think we all want to see a top 3, if not BIGGEST storm ever in the region.

Snow was a little faster getting here, already a half inch or more in Roanoke and should be starting in Lynchburg soon.

No changes to my snow totals. I like where the models are.


Today- Snow, heavy at times. Best snows will be an inch an hour or so.  6-10 inches
This evening. Snow heavy at times.. there will be a BIG band that works through. If this band maxes out here, this is the difference between 16 inches or 24. Some of the data showed this thing putting down 10 inches or so in 3 hours. That's 3 inches an hour for you math buffs.
Snow winds down towards 4-5 am or so. 8-14 inches.

Tomorrow- light snow and flurries, occasional moderate bursts. 1-4 inches additional.

Slight sleet threat in LYH, likely some sleet in Danville, east.  Total 14-24 inches, locally higher. Danville east 10-18

Will toss out updates all day in between sledding and other fun activities. The sleet threat is greatest 5pm till 10pm..

Shovels will be splintered, Scrapers will be shattered, records could be broken..

Much of the fun of snow storms to me is the tracking. The kid in me still gets excited when it when the first flakes fall, there isn't much I enjoy more than taking my kids sledding, and snow on the ground despite the cold makes me happy. BUT, when I get a good feel for what as storm is going to do and it behaves reasonably within those parameters and it such a good feeling.

We don't know the ending yet and last nights model runs are like a good movie-- you think you know what's going to happen but you're not quite sure. Looking at the set up way back Monday- I said the storm would trend colder HERE and they did. Now, we just sort out the details.

There are 3 major models I check (and a couple other I glance at) plus a few short term models that are important the last 24-48 hours. I don't just look at snow maps. I track surface lows, 500 MB lows, jet streams, 700mb vertical velocities..  and my favorite, soundings/Skew T to get a feel for the temps of the atmosphere all layers up to the clouds. Soundings are very important to figure out snow/sleet mix times.

Model data is VERY good agreement- Low pressure forms and once it's near NE Alabama it jumps quickly to the South Carolina coast and heads northeast to near Wilmington, NC to a point right off the VA/NC coast and heads East Northeast from there. The Euro finally stopped putting out 30 inch snowfalls and is in a more reasonable 20 to 25 inch range, the GFS had an epic run of 25 inches and other data falls in that range too.

I've mentioned the Euro model a lot. Last night's run was a more reasonable 21 inches. Our record snowfall is 21.2. Now, I REALLY want a record. That 21 inches is on a straight 10-1 ratio. If we get some fluff, we could see 25 from it. Here is the Euro with a snow algorithm that accounts for ratios.

If  that happens, we set a standard not seen for over a 100 years in our area. 

Here is a rough sketch of what I think happens over most of VA...

Most areas 14-24 inches, Locally higher. Some sleet may mix Friday evening . Danville to South Hill 10-18 inches, sleet will mix in. South East of Richmond, some snow falls but it does change to ice then rain, before ending as snow. They should see 3-6 total and have some sad kids who just want snow.

Snow start time is between 5-7 am in the west and 9 to 11 in the Lynchburg region. 

Two things that could go wrong:

1. We sleet more. Only one model has a warm layer and it's not that bad and mixes out quickly. If data moves this way, we'd have to evaluate totals in those regions. 

2.  We dry slot too soon. All mature lows develop a dry slot. This is modeled to stay to our south and east, but always worth watching. 

How to break the record:

1. No sleet. Obviously. 

2. Cool some layers of the atmosphere to maximize snow growth. 

3. Deformation zone. The epic runs of the Euro and GFS had a deformation zone (Cold conveyor belt) of snows that linger over our area. These are great ratio snows that are often 15-1 or more ratio snows. 

I don't make final calls. This is a living document and if we need to adapt, we will. 

My exact guesses:

Blacksburg 23 inches

Roanoke 21.5

Lynchburg 19.1

Danville 14.2

Thanks for the shares on FB/Twitter. We set a daily view record yesterday. I will continue the live tweets/ FB during model runs. May blog again later tonight but they end up not being read much storm days. Share your pics, measurements and observations on FB/ Twitter. 

Historic Storm on the Way..

No way around this one... A serious assault on the top 10 snowfalls of all time in Lynchburg, Roanoke, Blacksburg and MAYBE even Danville is on the way.

The one word that will prevent us from breaking a top 10 event is SLEET. IF we avoid sleet JUST enough, a top tier event is likely. The top storm in Roanoke is 24.9 from the Blizzard of 96 while in Lynchburg  is 21.2 also from that event. 13. 8 inches is needed in Roanoke for a top 10 storm while 12.8 is needed in Lynchburg.

In a stroke of common sense, the snowiest models have the least amount of sleet. The Euro model, which has trended colder and more south as it passes our area has NO sleet. The Canadian has no sleet as well on it's last run. The GFS and NAM have moved away from sleet mixing but still have some sleet. The Euro has 4 runs in a row had our snow totals of  north of 2 feet, even 30 inches a few times.  For my long time readers, you know I am very methodical about tracking the sleet and ice line. With that, the GFS and NAM have been very sleety, but have the most north track as well. AS they have moved towards more southern track of the Euro as it passes our region, we've seen a reduction in sleet. This will be a key to our forecast.

This is the most extreme solution offered by the Euro. This has a special algorithm that accounts for sleet, snow ratio's etc. This could be offered as "maxing out" this event, but wow,  setting a record in Lynchburg may not be that difficult. 21. 3 inches needed. Getting to 30, even 34 is amazing.  Going frame by frame on the models, we have a burst where in 6 hours Friday night about an inch of liquid falls. My hunch is that may be over done a bit.

I may draw a rough map, but this is my rough ideas now, Remember, I like to go UP as an event gets closer and not down in snowfall forecasts.

Roanoke, Blackburg and Lynchburg= 12 to 20 inches.  Some sleet could mix in. At this point, that mix with sleet would be the difference between 12 and 20 inches. If your area does not see sleet, 20 inches is the preferred total.  Higher amounts possible where the best banding sets up.

Southside- Martinsville area 10-16 inches, some sleet will likely mix.
Danville area 8-14 inches. More sleet mixes
South Boston 6-12 inches, even MORE sleet

Repeat: If any one place doesn't see sleet.. including southside, something near 20 inches is a likely total.

Timing: The storm is likely taking a more southern path to a point off of Cape Hatteras late Friday night. This path has slowed our start time down a bit to Friday Morning. Far west regions as early as 5 am and far east times east of Lynchburg as late as 10am or so. The storm should last into Saturday before it winds down Saturday afternoon. The worst of the storm will be Friday evening into overnight. Outside shot with a rapidly deepening low and strong upper air energy approaching that a rumble of thunder is heard too.

We won't have the needed winds for "blizzard" warnings but this will be a high impact event.

Obviously, school will be closed Friday. Most churches will be closed over the weekend.

This afternoon a small system will approach and could give us flurries to a coating. A coating after a few cold days if often a recipe for disaster, so be cautious on the roads if you do see some flakes falling.

Monday and Tuesday high temps go back into the low and mid 40's so a realistic shot schools open by Wednesday, possible Tuesday if we get the lower end amounts.

I will continue my tweets/posting as model runs come out. I'll be more specific and target information about possible sleet mixing and amounts. Please share this blog with your friends and families!

Morning update...

I actually got a good nights sleep, which is a nice change for me  when a storm approaches. I'm sure you all have seen some of the crazy outputs from the Euro, which 2 runs in a row CLOCKED us. One run had over 30 inches and one had 25 inches. Other model runs have had good snows 6-12 inches, but they mix with sleet/rain for a while.

Cracking the code on these to me comes  from understanding the physical evolution of the storm. I think I have a decent grasp on that now. The american model which has a decent snow for us 6-10 inches, but a ton of mixing. I believe this is because of the warmer look of the model, which doesn't force it to transfer to the coastal low fast enough. I think that's wrong because the short term models are just getting a view of this thing in the 70-84 hour range and they are colder. This cold air is what forces that low to redevelop quickly.

We end up with 2 waves of snow. Wave one is overnight Thursday into Friday morning. 1-3, maybe 2-4 inches falls. As it ends, we mix with some sleet. Danville and southside had more sleet, less accumulations and maybe even some rain. The lull could be as long as 4-5 hours from late morning to mid afternoon.

Coastal takes over pretty quickly and a HUGE wave comes through.. THIS is where we get the big accumulations. This snow could last until Saturday morning, with it being a 30 hour event.

Here is a SIM radar at hour 84... it's from the NAM..

Note how there is one area to our northeast and we are in a relative minimum area. At this time, 1PM Friday some light snow, sleet and freezing rain is falling. You also see that HUGE area to our southwest moving in. We've basically had a burst of warm air advection snow/sleet and coastal jump is happening now. 

That map shows a broad area of low pressure from Eastern TN down into FL.. this is what the euro shows but you're not allowed to post the pay maps I get. In the next map on the euro, there is a nice consolidated area of low pressure near Myrtle beach and heavy snow has moved back in to our region. Places that have mixed all along like Danville have changed to heavy snow.

I'm not going full Euro and predicting 24-30 inches, but I think we do very well. Even the warmer/slower transfer GFS has us getting 6-12 inches with a mix for an extended period.  All areas will see some what of a mix late morning, mid day Friday but the big show is when the coastal cranks up Friday afternoon and evening.

Let's revist floors and ceilings...

The Floor for Roanoke/Blacksburg and Lynchburg has been moved to 5 inches. I'd be shocked if we saw less than 5 inches. The ceiling 20 or more. Most likely, playing it safe is in the 10-15 inch range. Please remember that I always start low on snow totals and then go bigger. If A forecast is for 1-2 feet, and you get 12 inches, people feel let down.  So, we start small and then massage totals as needed as more information is available.

Danville/Southside. The floor is 3 inches.  I worry that Bug Island, South Hill could check in just under that total but we can adapt as we get closer. The ceiling is a foot or more. Most likely totals in the 6-12 inch range, highest Danville West to Martinsville, lower South Boston to South Hill. Again, subject to change.

Will tweet and fb updates as model runs come in. Please share with your friends. 

You Get Nothing!

How I feel waiting for the next round of models... Euro trended colder as I suspected and had a CRAZY output where everything went perfect and it "modeled" 30 inches of snow. DT from Wxrisk posted the map. I still have concerns over the amount of mixing that takes places. Would be the difference between 3 to 6 with sleet and rain or 8-12 or more. Will do full synoptic update later this evening or early tomorrow.

The BIG storm: What we know..... and what we don't know??

Social Media has been blowing up all day about the POSSIBLE big storm. Let's break down the details with What we know...and what we don't know??


What we know!

1. Cold Monday and Tuesday where temps don't get above Freezing most areas.
2. We will have a storm Thursday into Saturday Time Frame.
3. I expect Lynchburg, Danville, Roanoke and Blacksburg to have at least an inch of liquid fall (Could be snow, ice, rain)
4. Starting time could be as early as 9pm Thursday evening far western regions and as late as 9am Friday far eastern regions.

What we don't know??

1. Snow amounts. Social media will be flooded with maps from XYZ run of whatever model. There are so many issues with them I don't know where to start. 5 days out, we don't know yet. Remember, now we look broad and get specific as the event gets closer.
2. Exact storm track.. This is HUGE and ties into number one. Remember we want to be on the cold side of the low. This means the north and west side.. the model runs that take the low into Kentucky are NOT great for our region. My guess is a somewhere into Georgia, reforming near Myrtle Beach, but that's an educated guess. If a primary low drives UP into Kentucky, we are icy and rainy.
3, Exactly how much cold air will be in place and then reinforcing during the event. Antecedent cold air is very important for a big storm. However, getting cold air funneled in as the storm progresses is also important. Remember our Presidents day storm last year. We had snow and 12 degrees and it changed to sleet-- we had no cold air reinforcing the mid levels. Model data has trended a bit colder and I think this may continue for another day.


Wow, you said a lot of nothing...

YES I DID! 

I can speculate a little. This is speculation and will change. My goal will be to create a framework and then fill in the fine details as the event gets closer.

1. I believe the models will trend colder over the next day and give a decent idea of what to expect. The warmer models have stepped towards the colder models and the colder models conceded a few points and it's slowly coming together. The ensembles (same model run at lower resolution with some intentional changes added to weed out biases) have been more south and colder than the "operational" runs.

2. Once the models bottom out cold/south track wise- we see what corrections will be made back north and warmer.

3. Basement and ceiling for main locations...

Roanoke/Blacksburg- Lumped in together because this has some marks of an I-81 special. The floor of snow and ice accumulations is 2 inches with a ton of ice and freezing rain mixed in. The ceiling is a storm of over a foot or maybe more. Their odds of over a foot of snow is HIGHEST at this point. I'd estimate 40% at this point.

Lynchburg-  Basement is the same 2 inches of sleet, snow and slush. Ceiling is also over a foot of snow or more but the odds are much lower at only 25 %. Their 40% number is 8 inches.

Danville and Southside- Basement is a coating of slush and sleet, ceiling is also a foot but odds are down at under 10%. Their 40% number is 6 inches.

As we move closer, I will update and refine to give more details. We will be moving from broad to specific.
Please share my blog on FB/Twitter. If you like what you read, click and add---  I do get paid for that. :)

I'll continue to live tweet thoughts and progression during model run times. Feel free to retweet or ask me questions.

First Measurable snow of the season likely tomorrow.. Friday looking healthy!

Now, Measurable means more than a trace. I think most places see a coating to an inch starting near sunrise and ending early afternoon. A few lucky places, best shot from the VA/NC border to 460 could see up 2 inches.. depending on where banding sets up.


Friday's event looks better. Our problem getting snow has been that the flow is fast with many moving pieces, which prevents cold from meeting storms. (Adding many shortwaves working against each other)

It seems like the cold air SHOULD be in place as a low approaches from the west Friday...

3 options...

The Canadian model cuts the storm well to our west, we have some cold air and should get a snow to sleet and ice event, maybe even rain for  awhile. Shows big snows JUST north of here (Staunton north, Up 81 into PA)

The GFS (American model) storm cuts west but reforms south. We flirt with the rain/snow ice for a while in the event but still see a pretty big event. Not throwing out snow totals but it would be nice event.

Euro- more suppressed with the event and the storm goes out to sea we are on the northern fringe. Possible low Warning event (3-6 inch range type deal)


Looking at the pattern, I think we trend more towards what the Euro shows at this point. The GFS was a HUGE event, but in part was overdone because the cut west held on too long and pulled in a lot of warm air, making more precipitation. Still, Gulf Lows always have good potential.


Cold weather this week-- 2 days won't get above freezing.  (Monday, Tuesday) and Friday may not if the ice/snow comes early enough.