Could we see a Festivus Miracle??

 

Model data mid and late week last week looked promising for  pre-Christmas snow. There was a lot of chatter on social media but because this pattern has been delayed or not developed as modeled, I was hesitant to mention it until it seemed more apparent an event would take place. Long story short, cold air is on the way but the pattern won't allow the energy to dig enough so we will warm up just long enough to rain then some VERY cold air settles in as Christmas weekend will be below freezing. 

Artic fronts like to have a squall line and or strain out all the moisture as the come through but you need a little energy and moisture along and behind the front for this to take place. Some model data suggest this is POSSIBLE.  From 6am-10 am Friday the SUPER cold arctic air pushes through and we go from 35-40 to 20 degrees in a few hours. There is a slight chance rain quickly flips to snow and get a quick coating to an inch. Best chances will be along i81 and then slightly east of Lynchburg due to down sloping off the mountains. My current odds of these regions seeing accumulating snows under an inch-

Blacksburg 50%

Roanoke- 33%

Lynchburg 25%

Danville 10%

The GFS model (American model) is the most aggressive with rain ending as accumulating snow Friday.  Best shot at a coating to an inch will be above the blue line based on historical data. 

Brief guess...

Ice is inevitable..

Timing of onset vs timing of change to ice will dictate how much snow vs ice we get. What started as a Saturday into Sunday event is now a Sunday event. Some data even has an afternoon start of the storm. 

We will have crazy cold air in place. Temps could be in the teens with snow then ice falling.  This will be snow in the south in places like NE Georgia, TN, upstate SC and into NC that changes to ice. The concern is that as the low moves our direction the BITTER cold is leaving and allows the storm to take an inland path that always leads to some ice in our region. The other odd factor is that because the air is so cold, the precipitation holds off because of the dry air and then starts as the cold air is leaving. Double whammy. 

To get the most snow we need it to start early Sunday AM. Completely possible, but just may not happen. If not, we will get a GOOD snowstorm but it will go down as another mixed bag in much of our region that "could have been".

The mid range euro and NAM, short term model has snow over most the region by 1pm, temps in upper teens and lower 20s.  General rule of thumb is snow tends to change over faster than modeled. This could be the exception but I'd not bet against it.

At 7pm here is an image of temps at 5k feet. Simple put, blue shades are below freezing.  Ice is well into SML and Lynchburg  and likely even farther west with a warm layer being above this one layer.

Southside- highest risk of serious ice after some snow.  Snow range 3-8 inches then ice. 

SML to LYH area- moderate risk of ice after a significant snow.  Snow range 5-10 inches

Places west of the Blue Ridge, I 81 region including Roanoke, Blacksburg and Lexington. Mostly snow, may have some mixing. 

8-14 inches, maybe more. 

Places that remain mostly snow should see double digits. 

Woah, that was fast! 3 to 8 inches of snow likely region wide.

We have a storm on the way. High risk, high reward type event where the margin for error will be very small. 

1. The storm isn't a shock but the magnitude and intensity of the pending event could be shocking. It was on the models off and on all week. We needed the upper air energy to close out and space out and it did EXACTLY what was needed. Adding, if we had any cold air in place this would be a historic snow for much of VA. Instead it's 61 as I type this. 

2. Timing is key. It will snow but a few degrees warm, precipitation moving to fast, etc could be the difference between a slushy inch or two and 7-8 inches. Cold air being a little to slow or storm moving a little to will really change the outcome of the event. 

Timeline- 

Rain develops late evening and overnight. Rain should be hard. Between 4 am and 7 am, the rain should mix with and change to snow. Whatever is falling will be heavy. Snow should between 9 am west and maybe closer to noon eastern areas. Snowfall rates may be among the best we've seen here. Some "hour" data shows several hours of 1-2 inches an hour of snow falling. 

Snow totals- In general, 3-8 region wide is a good guess with a strong understanding this is not a "locked" forecast at all. One thing goes wrong, we end as flurries- conversely a deepening low could flip it to snow sooner and someone gets over 10 inches. Both options are viable at this point. 

Serious ice or serious sleet? Big event on the way region wide.

 Winter Storm watches are out for everyone in our region for a little snow, some sleet then ice. 

The basic set up is we have a piece of the polar vortex moving across New England pushing cold air into our region at the same time the "south east ridge" ridge means warmth in weather terms. This battle between the warm and cold will make for very moisture laden system with precipitation amounts of 1 to maybe 1.5 inches. 

I'm somewhat optimistic at this point that it will be a serious winter storm in the NRV to ROA to LYH with some icing concerns but we may just see enough sleet to mitigate HUGE issues with our power grid. (May, not a lock yet) This could keep freezing rain total UNDER a catastrophic level. Southside is another issue where they will get mostly freezing rain. As bad as the Farmville to Charlotte to Halifax area saw, this could be worse and more wide spread with more precipitation and colder tempatures. 

1. It may be a smidge colder, especially early on. You may be shocked to know that ice builds up more at 29 degrees than 31 or 32. 

2. It may rain harder, which is actually a good thing with freezing rain because it can't freeze fast enough but the duration will likely offset this. 

Basic Details:

Snow sleet and freezing rain develop overnight Wednesday into Thursday. Midnight to 4 am)

Southside: Quick burst of sleet to freezing rain. This will have a huge impact on the power grid. An inch or more of freezing rain will fall and build up on trees, power lines etc. I expect serious issues in this region with long term power outages.  Ice build up will be greater than a half inch most areas. It may take days to restore power. 

North of an Amherst to Daleville line, precipitation may start as an inch or two of snow, then sleet. 

** Caveat** The GFS blast a quick burst of snow from the NRV to Charlottesville that is in the 4-8 inch range before ice. I don't think it's going to happen but wanted to throw it out there. This gives Lynchburg an inch or two at the same time before any sleet falls. 

NRV to Roanoke to Lynchburg- 

A quick burst of snow will flip to sleet. We should see a good bit of sleet before freezing rain because the "warm layer" sits pretty high, above 5000k feet and from that point to the ground is a solid 3--6 degrees below freezing. That's a classic sleet signal. We could see between 1-4 inches of  quick burst of snow then mainly sleet. This should eventually mix with then become freezing rain and we will get a quarter inch of freezing rain build up. Most places had that in this past event, so I think we can mostly survive without HUGE power issues. With that, this is a Fragile forecast because if we change to freezing rain sooner, the Ice build up and power outages will be greater. 

For this region, I mostly see 1-4 inches of sleet, then freezing rain of about .25 build up. This is close to a crucial breaking point but hopefully we stat at this level. 

Temperatures may creep above freezing later Thursday but the damage will be done. We have better antecedent cold air, so there is a shot we remain at 31-32 until Friday AM. 

I'll pop some images on the bottom of this post but here are two- the top is predicted sleet  and ice accumulation from the RGEM model.  Note the sleet is total in inches and that in general 1 inch of rain is 3 inches of sleet. (meaning that most those in that area see an inch of precipitation fall as sleet.  Also note that the freezing rain map counts all that has fallen but it all won't freeze because when it is HEAVY freezing rain much runs off before it freezes. With that, those totals over 1.5 inches will be catastrophic. (At this point, those in Southside and Northern NC)

Wintery 10 days coming up- can we do better than mostly ice?

 We have a fun, fascinating pattern setting up where a piece of the polar vortex will position itself over the upper Midwest. (Great for Cold)

We also have a Southeast ridge based on other issues in the pattern ( Leads to warmth for the southeast) We sit in the Northern part of the south, tucked in near the Blue Ridge and quite honestly, the next 10 days will be chaotic. 2-4 chances of winter precipitation(and rain) We could see 2-3 inches of liquid in that time frame and trying to separate what falls when and where will be a challenge. 

Event 1 2-11/12. Cold air sinks in from the North, rain changes to freezing rain then sleet and perhaps snow. In general the further north you go the more sleet and snow you see. This likely won't be a big snow maker but 15 miles may be the difference between 3inches  of a sleet snow mix and a half inch of freezing rain. 

* I think the kids are out of school regardless most places Friday and maybe even Thursday*

Event 2 possible as early as 2/13 or Saturday as another weaker wave drops some light freezing rain during the day Saturday. 

Event 3 has the potential to be the worst of the three. This would be on or about February 16th.  The cold air REALLY builds in at the surface and some data suggests an ice storm that starts while temps are below 20. This would be Monday into Tuesday time Frame.  This is just one plausible outcome, but isn't the forecasted outcome at this time.  Liquid amounts of over an inch with temps in the teens rising towards freezing has BIG TICKET written all over it. 

This is a map of the heights anomalies. In simple terms, heights are calculated by the average temperature below that level. Those area blue and purple along the Canadian border and much lower than normal heights, meaning COLDER than normal temperatures. (Actually a piece of the polar vortex is there) The red over the Southeast USA is higher heights, or what should be warmer than normal temperatures.  

This gradient between higher heights and lower heights is creating all these storms. Cold air likes to push south in this pattern but is being pushed back by the Southeast Ridge. If that ridge wasn't there, we'd be cold and dry and that meaning very cold.  If that colder anomaly was not there, we'd be rather warm. What makes our situation unique is the Blue Ridge Mountains where the cold air, which is heavy and dense gets trapped and can't be moved out. (Remember, cold heavy- warm, lighter)  Some of the data for our storm Tuesday has surface temps in the teens but 5000 feet above temps are in the 40's. For those who remember the ice storms of 1994, this pattern is not far off looking 6-7 days out. 

The first of three chances is on Sunday- Monday.

 The long story short is we should have 3 distinct chances at some wintry precipitation starting Sunday. We can get all 3, we could get 2-3, (Which by Meatloaf standards isn't bad) We could only strike on one event and we could miss all 3 (And with three strikes you're out)

Setting up Sunday is a storm cutting to our west Friday that cause some rain then drag a cold front through.  A second piece of energy will then trail up that cold front. Where this gets dicey is- some model data doesn't push the cold through enough and primary low goes into the Ohio Valley then a secondary low forms. This set up ALWAYS changes us over or event starts as ice or rain OR the boundary could push too far south and is oriented in a way that allows it to escape harmlessly out to sea.  

I'm leaning towards Ohio Valley transfer at this time- but have plenty of time to adjust. This favors more snow in western regions, mix/rain set up East of Blue Ridge and Mainly Rain southside. 

Event two will be about Feb 11 second change at a winter event. (It's also the 38 year anniversary of the Megalopolitan storm of 1983 that dumped 15-20 inches region wide in our area of Virginia. I was 9 years old and we had true blizzard conditions at my home in New Castle, Delaware. 

We should have better cold air in place for this event and if there is any threat, it would be suppressed (To our south) or sheared (Upper energy weakens) and the storm falls apart. 

Looking past Valentines day, the 14-16 range may hold the best potential of the year as the blocking maxes out and just starts to relax. Often, in those relaxation stages a big storm pops. This is 2 full weeks out but this image shows strong cold air in place via upper air energy (starting the 50/50 lat/lon) with pieces of the a weakened polar vortex across the upper mid west. Energy near Cali indicates either ONE big storm potential or several smaller events if only pieces of the that upper energy comes out. 

The red stretching from Maine to Minnesota is a fragment on the weakened polar vortex while that red over the northern Baja is upper energy from the sub tropical jet.  

 

Again, this is about potential, not actual events. Things will change and adjust as we get closer. If you love snow, get your favorite lucky mug and if you are a snow hater, well- we went 700 days without accumulating snow. We know what they say about paybacks! 

Not a bad week, do we have an encore on deck?

 Well, region wide we did well with most places seeing between 4-7 inches of snow and sleet last night and today. For those in the Lynchburg vicinity, we broke out of our two year long snow drought. 

Wednesday night and Thursday ended being an official 2.1 inch snow.  I was a little worried when it was raining in Roanoke and 41 degrees here, but the "sounding" of the LYH was literally cold enough for snow, except for the surface. Sure enough, a few sprits of drizzle then snow. 

Last night and today was a bit of a challenge but one thing I said is that the 2 short term models that didn't have a decent snow were too slow bringing in the precipitation. Sure enough, that's exactly what happened. Round 1 was a half inch to an inch, we had a lull and fired up quickly, region wide as snow. Everyone had a little ice on top and now we sit at my house at 31.5 degrees. 

The Lynchburg seasonal total is officially 7.3 as measured by WSET while my house with 2 smaller events sits at 7.8 inches. 

We seemed destined for a week warm up and by the time the snow melts off the warm up may be only a couple of days. A late week storm will cut up into the Great Lakes regions. VERY cold air will filter in behind the storm Friday and some data suggests another storm forms and approaches the area Sunday. IF we get the snow and the cold, we will go in the ice box for a few days with multiple days possible below freezing. Here is a temperature map 2 days after the storm, at 1pm with temps in the TEENS across the region. Even if it is 10 degrees too cold, we are in the upper 20's early afternoon. 

So, road conditions will slowly improve tomorrow, we get a break from winter weather then we wait for the fine details of late weekend.  Could end up being just a blog that I post later isn't an option or we are forced to keep tracking it.