Tuesday, December 4, 2018

Weekend storm potential update!

Short Summary: Models continue to show the potential for a signficant snow event Saturday into Monday.

Can you tell me how much?? It is still too soon to throw out amounts. Most model data is showing  1 to 2 inches of liquid falling out of the sky for the event, and most of that is snow. There is a risk of some mix, all regions but especially southside regions.
(Snow is usually 10 to 1 ratio, so 1 inch of precipitation is 10 inches of snow.

Can this really happen, it's awfully early in the cold season? That's a great point and it would be quiet the anomaly for event over 6 inches this early in the season. For recent history, I moved to Lynchburg in 1996 and we had 1 storm 6 inches or more this early in the year, back in 2002 (And actually an analog year this winter too)

What can go wrong and we won't get any  or much snow? 
There is quiet a bit that can go wrong.

1. Storm remains too far south and we get fringed.
2. Storm comes too far north and we flip to ice and rain.

Both are possible. The models currently oscillate between a great track for our region and a tad suppressed, especially the regions north of HWY 460.

What can go right? 
I don't post snow maps 5 -6 days out. It's poor taste and people struggle with uncertainty. Simply beause the models change doesn't mean the event isn't or is happenning.

With that, some of the crazy runs had a large swath of 20+ inches across our region. This was accomplished by the primary batch of snow targeting our region and then the upper air support taking a great track that keeps it snowing another 12 hours that racked up the 20+ inches. Not a likely outcome, but could be partially right where we get the majority of our snow Sunday then a second batch falls into Monday Morning.

When will you give us accumulation ideas? 

If the model data is consistent, I will blog up tomorrow "floors and ceilings"..

Meaning, if everything goes wrong we can expect XYZ if Everything goes right we can expect XYZ.

Saturday, December 1, 2018

Next weekend's possible Snow/Ice event..

There has been chatter about this event for several days now so I figured I'd write up rather than short tweets and posts that lack detail. 


Dec 8 to 10th--

Set up:

Cold air filters in as an impulse rides along the sub tropical jet. This means timing is everything. Some runs are slower with the storm and the cold air is LEAVING meaning a chance to ice/rain while others are too fast with the storm and the cold air isn't here yet, meaning rain to ice to snow.  Models that show the storm starting overnight Friday are warmer to start while others that Delay the onset to Later Sunday end as Rain.

Could this be a significant event:

Yes, but a lot can and will change in 6+ days. Cold air is often not as cold as modeled and storms like to start a little quicker. (read above, this could mean more ice/rain, less snow)

What will I see on Social Media:

Expect a strong influx of snow maps from every backyard forecaster. Take them with a grain of salt. They often include what would fall as ice/sleet and even rain as snow.  They are useless at this time, and quite honestly most of the time.

Any initial guesses on accumulations:

Anyone who says they have a strong idea on what will happen at this point is foolish. Don't trust them.  Many of you may know I am Family Counselor in real life and in both meteorology and counseling, you have to be comfortable with gray areas and uncertainty. This is the case here.

1. It's early in the seasonan and we don't know the seasonal biases on the models yet.
2. We will have to deal with always present adjustment north modesl do  as we get closer.
3. It's a long ways out so the data will have several changes and adjustments.

With that,

Places along and West of the Blue Ridge  and north of Hwy 460 have the best chance of a plowable snow, with some ice mixed in, places south of that region may still see snow but now as much and an increased risk of ice/rain. 

I will start tweeting and posting maps and thoughts will more comprehensive blogs when I need to convey more information.

Thanks for sharing with your friends and family.

Wednesday, November 14, 2018

Early season Warnings, Watches and Advisories.

Pretty straigh forward forecast on tap.

Today will be cloudy and chilly with a chance of some drizzle. Temps will be steady or slowly drop.  For most of the region, temps will be mid to upper 30's by late evening. Rain and sleet move in from the south after midnight. Temps fall to and then below freezing. Rain will quicly mix with and then change to sleet, and then freezing rain will mix in. By mid morning most areas should be all freezing rain, with rain southside and then end as rain.  The western regions will have some snow showers over night Thursday.

I expect most schools to be closed tomorrow.  Road won't be horrible but they pretty much close for everything. Some places like Lexington and Covington may see 3-4 inches of sleet while Roanoke, Blacksburg and Lynchburg will see closer to an inch. Southside will have a trace and some ice but not a big deal.

I've attached a map from the NWS to show current watches and advisories and my call on ice/sleet.
I expect all the Blue areas to be upgrade to warnings, basically everyone along and west of the Blue Ridge

Decent sleet accumulations north and west of Roanoke and Lynchburg. They may never get above freezing some of those regions. Anything south and east of the blue line will see some sleet and freezing rain but only trace amounts. 

FWIW, pattern looks pretty amped the week after Thanksgiving. Thanks for sharing my blog with your friends and family :)

Sunday, November 4, 2018

Final Winter Outlook for Lynchburg, Roanoke, Blacksburg and Danville Areas 2018-2019

I did way too early outlook here and stated that we could see a rather cold and snowy winter. Because some other factors could change, I left it open ended where changes could be made to my initial thoughts.

So, did things change? 

Short answer is no. We still have a west based modiki El Nino that will likely be weak to moderate.  The  PDO looks to be positive and the majority of climate models show good jet stream configuration that lends to cold and stormy in our regions. 

What do the official mets say? 

The NOAA official outlook is normal temps. Many to most private sector mets are on board with a colder than normal and snowier than normal winter. (Look up Wxrisk, RaleighWx if you want two public access winter forecasts)

What is Normal for our region

Tempature data is accessable on the NWS Blacksburg but snowfall per region on a long term average:

Danville 10 inches. 
Lynchburg 17 inches
Roanoke 19 inches
Blackburg 22 inches. 

I am using long term because there were some data errors in the early 2000 and we also had some less snow winters in the 00-08 winters. 


In general will be 2-4 degrees below normal for the winter. 

 125 to 200% of normal snowall. 

Danville 14-22 inches for the winter .
Lynchburg 20-30 inches for the winter. 
Roanoke 22-32 inches for the winter. 
Blacksburg 26-40 inches for the winter. 

These as based on regions-- you should have an idea if your place does better or worse. EG: higher elevations in Roanoke like Bent Mountain do better than the Valley Floor on Orange ave. 

Confidence Level: 
The last super big winter, 09-10 I was fully convinced we were on the way to a banner winter. There are a few subtle differences that knock my confidence down a couple pegs but still lend credence to a big winter being on tap. 

25% chance we come in under my snow totals. 
50% chance we end up in that range. 
25% we out perform what I predict happens. Right now, these numbers put us just outside a 10 winter for our region. If this pattern develops as maximizes potential, we could end up with a top 5 winter ever. 

Winter Development

We will actually have a pretty cold pattern starting next week and will last about 2 weeks.  There is a decent show we may see our first flakes of the winter. 

December may favor a chance or window for a snowstorm, like late month between the 20th and New Years Day. 

I favor the pattern setting up for our "heart of winter" by late January. Late January through mid February should be highest risk for cold and snow. 

March could go either way but the pattern on many models still look solid for chances for snow. 

3 comparable winters:

09-10- Big December snow storm, 2 minor events. 
January- Big storm late month then active first 2 weeks Febuary. Lynchburg had storms of 12.5, 11.2 and 8 inches. 
No BIG snow storms but numerous events of 3-6 inches from early December Forward with a near miss where 4 inches of sleet would have been 14 inches of snow in Mid February. 
New Years Day snowfall of 3-5 inches, Back to back big snowfalls on Jan 22 and 26 of 10-15 inches and then another 2 events in February 

There are other years that have similiar but not as simialir patterns that had less cold and snow. (06-07, 87-88)

Share this outlook with our friends and make sure to follow Virginiawx on facebook and twitter for important updates. 

Saturday, August 18, 2018

Winter "Pre" Previews are trickling out.. If you like cold and snow you will LOVE..

Winter outlooks done by mets/ weather hobbyists are more fun than accurate at times but they do make fodder to read and post. I've noted a few notable mets with early previews and others tossing hints.

I have some early thoughts for the areas including Lynchburg, Roanoke,Danville and Blacksburg.

Most guess are predicated upon:

1. We will most likely have a low to moderate Modoki El Nino. This means the Pacific, especially in the mid pacific known as Regions 3/4 will be in an El Nino phase. 

2. The PDO should be positive- Warmer water closer to the north pacific coast from Alaska down towards the US will be warmer. 

3. The Atlantic MAY be more favorable for high lattitude blocking in the NAO and AO regions.

If you have every kept up with my blogs, those are all really good things if you like cold and snow. We always blog from the perspective that snow is a good thing,.

A modoki El nino is the closest winter  to a consistent theme.  Most end up remebered for being fairly cold and rather snowy.  Winters with similiar patterns were 86/87, 02/03 09/10 with other years having lesser levels of commonalities. 

86/87 is remember for have back to back 10-14 inch snowstorms in our area from Jan 22 to 26. Region had 30 to 60 inches of snowfall.

02-03 had MANY storms in the 3 to 6 range and a BIG storm ended up being sleet here (in the 3-6 inch range of sleet). The region had 20-50 inches of snowfall for the winter. 

09/10 had 2 storms over a foot and another get really close. Snowmaggedon dumped close to 15 to 30 inches region wide over a few days but DC north had 40 or more inches in a 10 day stretch.  Seasonal totals were 25 to 50 inches region wide. 

With that,  nothing is every a lock-- especially before we have an offical El Nino and a few other variables. 

If we get to October 15, we know the Modoki El Nino is happening and the other factors are in place, my winter outlook would be:

Temps regions wide-- Seasonal 1-3 below normal for the winter. 

Snowfall, by city. 

Danville region/southside- 10 to 20, but a lot wiggle room for more. 
Lynchburg Area 18 to 28 inches, with higher end potential. 
Roanoke Valley region- 21-31 inches, potential for more. 
Blacksburg, NRV and Highlands Region- 25-35, even more in Lake Effect areas. Also, potential for much higher totals. 

Each city's top 10 snowfall winters has 2-3 modoki winters in those totals. 

Modoki El Nino's are known for having 2 or more LARGE events of over 10 inches.. once snow gets into double digits around here, it's a memorable event. 

There is also a "hot" period from around January 20th until February 10th or so that has a historical precedent these large events with other events being more scattered thoughout the winter season. 

That time period is often easily identifed  in advance by-- Modeling showing strong blocking in the Artic/Greenland region (Negative A0/NAO cuplet) positive PNA(Ridge on the west coast) and the SOI (Southern oscillation index) dropping  7-10 days in advance. (This is tied into the sub tropical jet becoming active)If that happens we could pop 2-3 winter events in a 7-10 day period. 

A couple runs of the seasonal runs from the Canadian Model and European model showed literally perfect 500 mb maps if you wanted a cold and snow winter for December to March. These maps displayed blocking on the west coast and artic/NAO regions with clear evidence of a strong sub tropical jet. Sub tropical jet is very important for our region because we do sit far enough south that we need a pretty unusual pattern to have the northern jet suppressed for snow in our region. 

With that, we are only on August 18th and a lot can and will change.  It is completely possible that we have all the pieces I cited in perfect alignment and we end up with a rather tame winter. This outlook previews where I am likely heading, but will updated my thoughts hopefully by late October. 

Thursday, April 5, 2018

In Lynchburg, 1/10 of one inch of snow in April is more rare than a 10 inch snowfall any other time of year.

I've been light on blogs this winter for many reasons. One main reason is the many storm events AFTER daylight savings time.  Model data runs late and it's just easter to tweet out thoughts then an entire blog.

I've had several messages about WILL it snow this weekend.  Model data has been all over the place and knowing the lateness of the year I was certain the risk of snow was good, but models that showed 6+ inches were easy to discount. In 120 years of record, our largest April snowfall is 3.9 inches in 1907, our last inch was in 1992 and last tenth of an inch was recent, in 2013.

Since 2009 alone, we've had 5 storms above 10 inches measure here in town. So, any accumulation Saturday (Heck and Maybe Monday) is a big deal climatology wise, but not a huge impact compared to rain. (Rain or snow on April 7th will ruin your day but travel should be FINE, except maybe if it snows hard a few hours)

So, what will happen??

Data has gone from heavy snow well into NC and us being on the north fringe, to the best snows being north of DC, to now showing the best snow maybe to our south and east. Now, models don't control weather, they display what we MAY see happen.  There are a lot of moving parts, crazy cold air pushing in fast but pretty warm air in place before the storm approaches.

Rain pushes in Friday overnight and flips to sleet and snow before ending. Some data is pushing for another enhanced wave of snow for parts of the region after the chance to ice/snow.  Another storm pushes in late Sunday that could give ANOTHER coating or more of snow to parts of our region.

Rather than clutter the blog with pics, I'm going to post various maps from resources about the storm. Remember, anything that is a .1 of an inch is a VERY rare event. (Roanoke/Blacksburg see a little more and had over an inch in 2013, Danville Likely a bit less)  Some people are bullish on an inch or two in part due to the strong push of cold air with warm temps to the south could feed bands a little better than modeled. I'm not sold either way yet, and honestly because it's april I'm not overly concerned other than the "historic" nature rather than impact on the day. Sports would be cancelled with rain. If we see snow, it may impact your day a few hours but I don't expect long term dangerous roads.

So, make sure you have me on Twitter or Facebook under LynchburgWx/VirginiaWx.

Tuesday, March 20, 2018

Well, That esculated quickly..snow totals going UP!!

OK, Party people in the house! Who wants more snow??
Look at the bright side-- even if we get 8 inches, You will be driving tomorrow afternoon. March Sun is burtal, same angle as Late September.

I am going to beef up totals a bit, and even say- some places, Lynchburg especially I would not be shocked if we had 2 inches total or even 8 or 9.

Why? We have a strong contrast between warm and cold. Look at these dewpoint temps 8 over southern PA and 65 in North Carolina.
In simple terms, the cold air push is a bit stronger and the low is being forced further south. This should keep us in heavier snow longer and timed well. The snow last week- if you noted we hit 4.5-5 and stopped getting deeper when the snow slowed down. The best snows should fall overnight into mid morning but snows may linger a bit longer. If we were in January, We'd be talking about MAYBE  a foot or more. 

The snow will start in impressive fashion: all the models show some type of heavy band that fires up over NW North Carolina and explodes north and northeast. Any rain will quickly change to sleet and snow, then snow. After that first crushing band of snow, we should see 5-6- more hours of moderate accumulating snow.  By midmorning, it will keep snowing but hard to make snow depths greater.

What go wrong?
1. The band misses your house. Very possible, greatest changes east regions (Danville, LYH area.
2. Storm ends not not as far south (less of a band, less moderate snow after)
3. Sleet- greatest risk eastern regions. 
4. It may "snow" 8 inches, but only accumulate 4. March-- it will lay, but not the usual ratios. 

My map has ranges. I may be underdone southside.
Lynchburg: I have this theory about West to east moving upper air lows vs Southwest to north east. We usually do better than Roanoke in East west, and they do better in Southwes to north east. Last week, Southwest to north east- we had .15 more liquid and an inch more snow. (Feb 12, March 13 Jan 10 as other examples) We will put this to the test. Model data has slowly moved  heavier snow into Lynchburg. 
Why? My theory is the low level jet comes in better with the east locations and the "bands" I often mention are more mature  on West East moving upper air lows vs SW to NE bands tend to dry slot Lynchburg in a relative sense. This is another test of that theory. 

My map: I really just forecast the Roanoke/Lynchburg DMA-- If you are just outside, I did not review your area. :)

Share me with your friends and follow me on Twitter/Facebook at VirginiaWx. Will Tweet/post current obs, radar shots and other forecasting ideas about this event. 

Get this: MAYBE more snow Saturday!!