Friday, December 28, 2012


Model data- Worst type of storm with no real hedge.

Looking at the 0z NAM-- it's literally an 4-5 hour event if that. Flurries or drizzle for an hour, bangs to decent snow for 2 hours and ends as drizzle/flurries. Maybe an inch or two anywhere east of the  Mountains NORTH of the Staunton River.

SO, 1-3 mountains, Coating to 2 inches east of Mountains. Get up early-- snow ends fast and melts by early afternoon. :)

Danville, South Boston, barring a miracle this won't be your event.

**Heading to my Dad's in Parkesburg, WV-- stopped for the night in Lewisburg for the snow and a swim at the hotel. We already got a little sledding in. Hoping to get 4 inches out of this event up here**

The little event that won't--

If you've read my tendencies, you'd note that I usually blog when I feel strongly about the event. So, a blog this AM on the cusp of our first possible accumulating snow isn't a good sign.

Strike 1- Marginal temps. No model gets the last 2-4k feet below freezing.

Strike 2. Strung out low pressure. That's not a good sign for heaving precipitation. With temps near or above freezing we'd need heavy stuff to cool the atmosphere and or accumulate.

Strike 3- total QPF is forecast between .15 and .25-- that's much much either way and we know it will mix.

The NWS forecast is under and inch of snow in Roanoke and maybe a little ice in Lynchburg. These seem about right. Places like Blacksburg and Radford could see 2-3 inches and Hot Springs and Lewisburg could see 2-4 or so. Will update if any major changes, but I'm not expecting any. If anywhere east of the Blue Ridge sees an inch, consider that a blessing from the snow gods.

Tuesday, December 25, 2012

Ice event and the next 10 days.

Tricky forecast for Lynchburg, VA- Roanoke, a little easier but still tricky. Few degrees either way make a BIG difference.

The Good:
We need the rain and will get quite a bit. Between an inch and a inch and a half most regions.
Ice impact-- While we could see some ice build up on the trees in places that get freezing rain, but the rain will come down heavy so it won't have a chance to freeze as much + temps won't be that cold.

The Bad:
If I were king of the world, I'd of expanded advisories a county south and east of Lynchburg to include Campbell and Appomattox. It may not materialize, but considering the holiday, people heading to work-- if there is marginal temps a bridge or overpass is icy-- bad situation.

The Data:
Interesting trends as far as temps-- we spiked early and between the cloud cover later in the day and a little colder air dipping in from the north, we went from 53 to 43 in a couple hours. Temps will hover in the upper 30's until the rain starts. There is some dry air, especially between 6 and 10k feet. This will cool the atmosphere from the mid levels down mix the rain with sleet for a time between lets say 5 am and 10 am tomorrow. The surface temp will slowly drop as well and will stop in Lynchburg somewhere between 31 and 34) Obviously, getting below 32 is a big deal. Elevations above 1500 feet or so will get much more freezing rain. Just outside Roanoke in the elevations above 1200 feet should see a decent amount of ice accrual as well.

The issue with the sleet is this-- ideally, you want air colder than -3 or -4 C for 4-5 thousand feet for sleet. This is more like -2 or -3 for 3 thousand feet as modeled. So, this is marginal for sleet. However, some sleet will fall. I can see the ground getting coated for a period tomorrow between 7-9 am .

Biggest thing-- be careful in the am. Check the weather, warn your friend to check. A few degrees-- better safe than sorry.

The Future:
Saturday has a possible event on tap. AS of now, looks like a risk of a moderate snow event of maybe 2-4 inches. Still need to shift over the data. Part of the deal will be what happens with our first storm and where that ends up.

Jan 2-3 has another "potential event". If you track some of my blogs, I talk about the the "PNA" or ridging in the west. Seems like we MAY have some cold air and SOME chance of of a decent storm. I like the potential for 7 days out.

Monday, December 24, 2012

Bat signal engaged

Well, this may be one of my more terrible storms as far as the waffle. I felt good as far as where were we 48 hours ago, but the rapid and consistent move of all the models made it seem like that was the movement it was heading. I was expecting MAYBE a little sleet in Lynchburg to start, and Roanoke maybe a little sleet and freezing rain. Nothing that was a big deal and over early.

The model data started to shift back this AM and now all agree the other way. Taken literally-- 2-3 inches of sleet in Lynchburg and even more snow/sleet in Roanoke. The weather happens, the models try and guess.

The facts:

The storm arrives after midnight. When there is low level cold air, it's common that some places start as what seems as rain and as the intensity picks up it goes from that to even sleet or snow. There was an ice event in December of 2005 that started as freezing rain, went to snow-- back to sleet and then a pretty good ice event. This may end up somewhat like that.

Heaviest of the precipitation will be from dawn on Boxing day till mid afternoon.

The speculation:

If the colder trends are legit- we will have Winter Storm warning west of the Blue Ridge and advisories east, north of the Staunton river. Since .5 is a warning, these cold be expanded.

The issues:

We need the cold air to get here. If the cold air is a little later or storm quicker, we will get more rain and less ice. This is a very plausible option at this time.

I love these "computer generated snow maps- they are usually full of crap. this one is, as it's accumulating snow when it should be sleet. This one has from the GFS has 4 inches in Lynchburg near Campbell county and 0 down near Brookneal in Campbeel County. My guess is this map isn't seeing the warm air above 5000k feet and this is more sleet. As a result, it's more like 25% of what falls here like an inch in LYH. Possible, not a forecast. Yet.

Sunday, December 23, 2012

Pulling the plug

Well, well, well-- In literally a day, we went from a decent event to "mainly" rain. I'm not ready to proclaim ALL rain, but the good news in all this is we have been dry and the 1 to 2.5 inches of rain between Christmas eve and Boxing Day will be welcomed. 

What happened??

The storm cut much further west, pulling up warm air in front of it and-- despite the models looking about the same, my take is it over did the cold air to begin with. 

More rain later in the week and "maybe" a winter type event Jan 2-3. 

Saturday, December 22, 2012

Vanilla swings by after Christmas--

I've been waiting to fire up the bat signal for this event for a couple days (plus having Christmas fun with the kids). It's been clear there will be an event Boxing Day for 2-3 days now, but the fine details are waiting to be hammered out. 

Showers Christmas eve-- Mostly dry Christmas day. Snow and sleet (freezing rain southside) develop overnight Christmas and begin that transition into freezing rain and maybe even some rain during Boxing day.

If your want "long term guess" on accumulations. LYH area- 1-2 inches of snow and sleet and a pretty good glaze of ice. ROA and BCB 2-5 inches of snow and sleet, some glaze. Southside- Less sleet, more glaze and rain. Best chance for 6 inches of snow or more will be Staunton up to Harrisonburg.

We will be getting into a colder pattern with several chances for snow and ice starting Dec 26th. Other dates include around the 29th and Jan 2-4th.


Low pressure forms and attempts to move up to our west- Let's say from East Texas to East Tennessee. There is a block up to the north that force it to "jump" to the coast at some point. At the same time, colder air is being forced east of the mountains by a "banana" high and cold air damming will provide us with a winter event. Good shoot this will be a "warning" criteria event. (Advisory means lower impact)

Notes on map- the blue line is "freezing" line at 5k feet. note how it's being forced down east of the Blue Ridge. This is in response to that "cold" on the map. If you can read the "pressure" lines note how they are bundled up around the storm and broad near the high pressure bringing the cold. Further, note how they "bend" east of the mountains. This will supply cold air that starts most areas as snow and then transitions to sleet and then finally freezing rain. Southside into Farmville has a good shot at having some plain rain too.

Further updates later today.

Wednesday, December 12, 2012

May your days be merry and bright

And may all...

My December portion of the outlook has been an epic fail as we are running VERY high departures so far and still have some days of above normal before a colder snap.

Social media has made the local TV meteorologist job hard-- because of Twitter, Blog and FB people have access to comments from many source and some (like me) even read the models themselves. With that, some of the model data yesterday seemed to indicate a SHOT at some snow next week. My take was I thought it was bad run of the model and didn't comment. Seems like I was right--(as of now :)

With that, a colder pattern is creeping in. We'll have a few waves of storms between now and the end of next week. Snow WELL up into New England will be common along with some sleet and freezing rain. Boring stuff to your average person down here in Lynchburg, VA

The problem with our pattern has been that while we've had decent blocking in the Arctic and heading that was with a -NAO, the pacific has been a mess with a trough over the west coast (leads to ridging over the SE USA and remember Trough== cooler, ridge== warmer. Also, some of the higher lattitude blocking signals we monitor called the EPO has been positive, which doesn't allow what is called cross polar flow (AKA- getting the coldest air to our side of the globe. It's been pretty cold over Europe)

Those signals look to be getting better and with a pulse in the SOI-- which is a scale that measures pressure differences between Darwin and Tahiti, it also seems to be linked with "energy" in the sub tropical jet. There is about a 2 week lag time from a pulse to an event, so crude math says between December 24-27th or so is a decent time to think SOME colder air could be local and SOME type of storm cold be in our area. This is conjecture and by no means a forecast, but we are keeping our eyes on this time frame.

Also, mid week system next week COULD drop some Mt snows on the back sides, so if you have a cabin at 2500 feet get ready! Updates will be more fequent as the weather is getting a little more interesting.