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Tuesday, February 9, 2016

Let me elaborate on Single Digit Cold and Double Digit Snows..

And how the Euro backed off a little last night.

We will get some very cold temps this week.

First, the event yesterday went as predicted with some rain, a little snow and temps did bottom out last night below freezing so watch out for black ice. A few flurries are possible today, maybe even a snow shower.

The euro yesterday showed low temps Sunday below 10 most regions and then a NICE storm that dumped double digit snows in our region. Last night's run had lows closer to 10, with the snow more like 6-8 inches and ending as ice places east of the Blue Ridge (Lynchburg and Danville)

Other models: GFS had a weak low to our north while the Canadian (CMC) had a look close the the Euro.

Take Aways: We will have some serious cold. The storm has some issues with cold air leaving, timing where if it's a day late we get nothing and there is ANOTHER short wave (Energy aloft) right behind it. The Euro ensembles look better for snow than they did noon yesterday, but are not perfect and I've not seen the PARA euro (new version of euro in beta phase) missed off the coast yesterday. 

I would classify this as the "monitor" phase.. not a threat phase yet. If it comes to fruition, it will be a Monday possible ending Tuesday, but a fast mover. 

Wednesday, January 27, 2016

The big warm up and then?? Historical snows in LYH over 10 inches.

We will get a NICE warmup a few days next week and other then the MEGA MALL snow piles, the snow will be gone.

A few thoughts..

Our official snowfall from the last event was 10.1. WSET takes those totals. I'd argue it's a inch low. They "only" said we had a half inch of sleet and it was a good 1.5 inches total from when I cleared to when it mixed to when it went back to all snow.  I think some of the wrap around snow blew away and they wiped the board to late after the mix with sleet.

Kevin Myatt from the Roanoke times had a blog about big snow events since 1947..

Roanoke's foot-plus snows since 1947
Feb. 20, 1947: 14.5 inches
Feb. 13-14, 1960: 15.7 inches
March 2-3, 1960: 17.4 inches
Feb. 7-8, 1961: 14.2 inches
Jan. 22-23, 1966: 13.7 inches
Jan. 29-30, 1966: 12.3 inches
Dec. 25-26, 1969: 16.4 inches
Feb. 10-11, 1983: 18.6 inches
Jan. 25-26, 1987: 13.9 inches
March 12-13, 1993: 16.0 inches
Jan. 6-7, 1996: 24.9 inches
Feb. 2-3, 1996: 12.2 inches
Dec. 18-19, 2009: 17.8 inches
Feb. 12-13, 2014: 19.0 inches
Jan. 22-23, 2016: 13.0 inches
Close, but not quite
Jan. 13-14, 1968: 11.7 inches
Feb. 27-28, 1982: 11.4 inches
Jan. 22, 1987: 11.0 inches
Dec. 7, 1995: 10.2 inches
They have 19 double digit storms since 1947..
I'm going to lower the bar to 10 inches and compile the same list of LYH. 
January 6-7 1996 21.1
Match 5-7 1962 17.7
Feb 11-12 1983 14.6 
Jan 31-Feb 1 1948 14.5
Feb 28-March 1 1969  13.7
March 12-13 1993 13.0
Feb 13-14 1960 12.8
Dec 25-26 1969 12.7
Jan 22-23 2016 10.1
Feb 12-13 2014 10.0
Jan 30 2010 11.4
Dec 18-19 2009 12.5
March 1-2 2009 10
Feb 1-2 1996 11.2
2-27-1982 11.7 
Jan 22 1987 12.2
Jan 25-26 1987 12
Feb 16-17 1987 11 
March 2-3 1960 12.1
Jan 25-26 1966 10
Jan 29-30 1966 10.9
Dec 23-24 1966 10
Feb 15 1958 11.9

Lynchburg has 23 double digit storms in the same time frame. They have quite a few bigger storms, but I think we catch a few coastal bonus inches here and there and grab a few extra storms that reach double digits. 

Looking at those stats:
LYH gets a double digit storm every 3 years while ROA has to wait every 4 years. 

HOWEVER, storms over 15 inches happen every 10 years on average in Roanoke but every 30+ years in LYH. 
LYH cashes in on some coastals that Roanoke doesn't quite make double digits, while the BIGGER more wrapped up events tend to give Roanoke higher accumulations. 

We warm up after the weekend and then another BIG cold shot comes in. Looking at some patter ideas.. between February 6 and 10th may be or next storm window. From our good friend DT at Wxrisk.. some of the model data isn't that far off pattern wise from our BIG event that just passed. 

That 5 days will be colder than the 5 days near our big event. At times, the pattern looking 2 weeks out has also resembled our 2 week stretch last year that had 22 inches of snow in 10 days. Point being, we don't know the fine details at all but the likelihood of cold/snow and ice are likely on the way back after a brief respite. Will start to tweet out if interesting model data comes out and will update every 2-3 days on pattern ideas until our next threat. 

Saturday, January 23, 2016

Post storm wrap up.. Important, read and share.

This storm has been fantastic. Hey, I love snow likely more than all of my readers and really wanted a record. Still, 10-12 inches across Lynchburg, more west in Roanoke and less in Danville is a big deal.

I will record this as 11.5..

7 inches before sleet mixed in.
1.5 sleet/sleet mixed with snow (Cleared snow board)
3 inches of snow after.

It compacted and drifted.The last bit of snow was good ratio stuff and blew around and compacted quickly.

The models did great in the BIG details days out. True story, I bought my one son boots who didn't have it when I saw this on the models 10 days out. My daughter also asked to travel with a cheer team to Hampton Roads area and said sure, but I think it's going to snow and be cancelled anyways.

So, in that essence good call.

What happened to the BIG totals? 

Short answer is we only had a liquid total of 1.29 in Lynchburg , 1.59 in Roanoke and 1.03 in Danville. Most model data was between 1.75 and 2.5 or greater.

We knew sleet was a threat. Dry slots.. always happen. We got them both and it doomed even a top 10 event.

Funny that all model data, even the "NAM" (North most model" had 15 inches, GFS had 24 and Euro had backed off to 20-21 inches or so.


1. Sleet.. We knew it would mix or get close. If we had gotten the nearly 2 inches of liquid We'd of ended up with 18 inches or so.
2. Dry slot.. The storm "jumped" to near the GA/SC coast early on but the development process took longer, When the sleet mixed in there was strong echoes to our east near Richmond and another band that hit us with the heavy sleet. Those bands somewhat died as the coastal cranked up and pulled our bands out quickly. I had anticipated we'd maybe mix we sleet, but we had very little relative precipitation in this time after the sleet burst. I thought, and the models showed us going right from the warm air snows to the "coastal" snows and that simply didn't happen.

Part one of the storm.. 4-8 inches, we got 7, Middle part.. I thought We'd snag 8-12 and we got 1.5. Part three once the coastal cranked up I thought 2-4 and we got 3. Middle part killed us.

Lessons learned:
Speaking of Lynchburg- our snow history is full of storms between 10-12 inches that were big, but not historic. Since 2009, we've had storms of 10, 12.5, 10 and today will officially via WSET be 10.1.

Since as far back as we have records: We have 3 storms over 15 inches "officially"  Blizzard of 1996 at 21.2, Knickerbocker storm in 1922 at 20.2 and Ash Wednesday at 17.9. There are 3 clustered between 13 and 14.9 and then an overkill of storms between 10 and 12 inches (Double digits always seems impressive.)

Considering this, It would have been more prudent to stay in the 10-18 inch range on most forecasts for LYH and DAN. People hear 14-24 and think 24, not 14.

Roanoke has some higher ended totals and 2 top 5 storms in the past 6 years, but still coming out bigger than 18 isn't common and likely destined to fail.

Letting the public know what is on the way when 2 inches shuts the city down is what is important, nothing more. It's always better to go UP in totals, not down as the event approaches. 12-18 conveys a BIG event and hedging for more possible is quite enough considering we've had 5-6 storms that were clearly above 13 inches in 120 years. So, I will only go 12-18 total snows in LYH and DAN next big threat. Roanoke-- Likely the same call. NRV and 81 away from the city is a different ball game.

Be easy on your weather guys- they worked hard on this storm and all storms.

Moving forward: Watching a system late next week. Not NEARLY as locked in on our area as this one because cold air may be the missing ingredient. Looks like a fast mover if it does come to fruition.

After that- I think we get a nice 2 to 3 week break from colder temps. I don't think we end up as warm as Christmas, but I don't foresee much to track in that time frame.

I'm not convinced winter comes back in that time frame as February 15-20 winter COULD return for one last blast through early March. e have mixed signals on that, but the potential is there for another 10 day stretch with a couple of possible threats.
In e

Friday, January 22, 2016

Sleet has mixed in Lynchburg.

I'm not sure what to thing-- it's a couple hours faster than modeled. However, thundersnow has broken out N of Charlotte. Once the system matures, we should mix out this warm later. I'm not 100% how this all plays out and I've tried to convey this all along.

I've got 7 and head reports of 7-9 all over the area so far.

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..

Thursday, January 21, 2016

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. 

Wednesday, January 20, 2016

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!