A Model Idiot?

The models are struggling with this event and it's not unexpected. With VERY cold air in place, being dislodged as the storm comes in, the models are struggling. I expect the models to trend much colder as we approach this event.

at 84 hours, here is the GFS (American model) It's trying to hold cold air in place to the east, but eroding it to the west. As a result, it's 31 in Richmond with snow and 40 with Rain in Roanoke (1pm Monday) This never happens.

At this point, there has been a couple of inches of snow. 

Here is the NAM at the same time. 

The wedge is in much better shape and we've had as modeled, 3-6 inches in our region. What happens is warmed air overruns the cold air trapped against the mountains. This reinforces the cold air to hold in place longer.  It would infer that snow would be here sooner and heavier. 

There should be some type of a 30 mile wide band of heavy snow that develops. Being on the southern fringe 84 hours, may not bode well BUT once it gets a full grip on the cold air in place, it may actually trend south before it trends north again. 

What does this mean?

Snow starts after midnight Monday west and races east by 3 AM (Lynchburg area) Monday is pretty snowy, could be heavy at times with 1-3 near the VA/NC state line, mixing early and 3-6  HWY 460 north. This will eventually mix and change to freezing rain from 460 north and back to I-81. Could be as early as early evening Monday, could be as late as Midnight. I think we stay below freezing until Tuesday AM.  If we change early that 1-3 south, 3-6 north will be the ballpark of total snow. IF we can cling to snow until Midnight or later, those totals could double. Then we tack on some sleet and freezing rain. 

Here is a sounding at 84 for LYH (1pm Monday). I've circled the temps.. the lower you go on the chart I posted, the higher the you are in the sky. You see some temps between -1.5 and -2.  I suspect the warmth comes in the area that is near -3. I would suspect this is at least a few more hours of snow. Height in second column is elevation in meters. This model isn't great at 84 hours, but I think the better resolution is catching on sooner. 

I will continue to tweet out thoughts as model runs continue. I do have growing concerns about power issues in the Roanoke and Lynchburg area. Even if we just get 3-6 inches of snow and then freezing rain, the weight of the snow PLUS adding on ice could be BIG trouble for trees and power lines. Double those snow totals and it's even worse

One half second too slow, too fast and you don't quite catch it...

Long day of glancing at the models in between working hours ends with no clear idea. In the end, it's all about timing.

The model runs that are faster with the storm, bring us the most snow.  The models that are slower, because the cold air is fleeing fast end up icy and rainy. I just saw the euro and it's a nice compromise compared to where it was before.



The fast models bring in snow before sunrise Monday and lasts most of the day. By evening, ice has reached Lynchburg and the worst ends by pre dawn, if not sooner. (Little moisture left by 1 am, I imagine Freezing drizzle falling most of the night) Temps are well below Freezing as the storm ends.

The slower runs at times hold off the snow until Monday evening and then quickly break down the cold air wedge, going from a little snow to ice and then rain. Some of those runs have the bulk of the rain being Tuesday when the cold air is all but gone.

The key because the cold air is leaving is the speed of the storm. The slower solutions do end up with more total precipitation because the flow of moisture last longer.

So:

Fast solution: Snow develops pre dawn and snows all day. Mixing first southside, then Lynchburg late afternoon finally into the Roanoke and NRV as it ends, 2-4 southside with ice, 3-6 LYH with ice, 5-10 with ice Blue Ride West. Storm is gone shortly after midnight, but I imagine some freezing drizzle and flurries could linger over night.

Slow Solution. Flurries afternoon Monday, some snow  early evening and then ice into the overnight, could be heavy, eventually flipping to rain. The further north and west you get, the more accumulations you get. If this pans out, I would see southside with little or no snow and some ice, LYH at 1-2 inches at BEST of snow and ice ending as rain Tuesday. Roanoke 3-6 with ice ending as rain Tuesday. These solutions linger rain or possibly ice into Tuesday Afternoon.

It's about a 12 hour difference in timing. We could blend these two ideas as our final outcome.

No real model consistency, but I just saw the euro and after being the SLOW solution, it has gone to the fast solution. The PARA Euro, (Upgraded version, still in beta testing) has somewhat this look. I won't see the Para until after 8am or so tomorrow. Before the euro, I was hedging a stronger front running Monday, a break and then more ice Monday night, but the Euro is a nice compromise. Euro has most places over to ice by 7pm Monday, but it was a healthy 3-4 inches southside, to 5-6 near LYH to 5-10 western regions.

For those worried about power outages if we see big ice, I don't think this is a set up for widespread power issues. Usually you'd want to see moderate freezing rain for house with temps holding mid 20's or below. This would have temps in the mid 20's sky rocketing towards freezing fast and HEAVY stuff falling. Yes, it would have SOME power outages, but it won't be 1994 all over again.

I'll tweet out something when I see the PARA Euro between 8 and 9 am tomorrow.

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. 

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. 

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.

WHY?


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

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..