Rainmaker incoming! (ending as snow??)

Despite the record setting +AO, a storm approaches and bring a TON of rain-- upwards of two inches. Here is a smoothed map by the NWS RNK. Free plug for them, they are now on Facebook. If you keep up with your news feed they do often link various maps of interest.

The fun and tricky part of this even is that is COULD end as snow, especially in the Mountain Empire, NRV, Highlands where an inch or two is possible and maybe even into Roanoke (Maybe a coating) Lynchburg may end as snow, but the last 2k feet are a tad warmer and I just can see a few gloppy flakes falling. I'm never a fan of these events as often the models are a little too slow pulling out precipitation and as that doesn't always equate to the cold air being faster with the snow. So, I like 1-2 in the higher elevations west of 81-- maybe 3-5 above 2500 feet. If your an 11 PM news watcher-- Wednesday night may have some flakes flying as far east as Lynchburg. The Storm is all but done by 2 AM- even in Lynchburg.

I've attached 2 MAPS-- one is from the 6z NAM-- it's not that aggressive on the western flank with snow and the second is the outlook from the HPC about where they think 4 inches or more is possible. It's pretty bullish, more bullish compared to my current thoughts. 

HPC MAP- Best threat along 81--

 Blue is low risk and green is medium risk of 4 inches.

NAM 6z- 1-3 inches along 81.


For Giggle-- I will show the most aggressive model with snowfall- I think it's too aggressive and 

not factoring in the low level warmth well enough. 

I think this is over done as it has an inch WELL into NC, south of Danville and the 3 inch line knocking at Lynchburg's door.

Record setting POSITIVE Arctic Oscillation could be harbinger of coming winter--

I know my readers don't always get the technical weather talk and I strive to break it down where it's easy to understand. Back in the past 2 winters-- the Arctic Oscillation has been VERY negative in our very cold times, RECORD negative in 09-10 when we had those major snowfalls. This scale tells us in simple terms whether the cold air will be bottle up towards the north pole or be shoved away from the pole. Currently we have a NEAR RECORD POSITIVE Arctic Oscillation. (It hit OVER a +5, 2 highest reading EVER)

This doesn't mean we won't get any cold - but future events can be hedged by looking at past events. We can get cold here-- one of the years the DAY we set the record "Christmas Eve 99"-- there was a surprise snowfall in the Lynchburg area of close to 3 inches. (One of my favorite surprise events ever- I was tracking the clipper and it was expected to be dry east of the Mts-- the snow started just as a dropped off some gifts for a VERY special family-- was a special day) We can get cold air-- but long lasting cold air is harder to get. Ice events are more likely as there is nothing to FORCE the storm to our South and East.

Years with the record AO+  that took place in December,
Winter 51-52,  71-72, 75-76, 79-80,  83-84, 91-92. 92-93, 99-00, 06-07

Big snow winter-- 79-80

Average- 99-00, 71-72

The rest were BELOW-- some worse than others with 75-76,  83-84, 06-07 being among the 10 LEAST snow winters ever.

The two that are second yea La Nina's-- like this is would be 75-76 (Yikes) and 99-00.

99-00 had a really aggressive winter pattern with 4-5 events in a two week stretch and that was IT. The last even LOOKED to be a big snow event but as it trended closer became a snow to sleet to ice to sleet with 2-3 inches near LYH of ice/slush and more like 5-7 out in Roanoke. The BIG event was a surprise event on Jan 25-- that shocked us all. The synoptic pattern was unique in that there was a negative tilt troff sitting just of the SC/GA coast and a shortwave dug in like crazy and blew up. There was a ton of dry air aloft and so it was literally 10 minutes from 8 inches of snow in LYH to NONE in Bedford. My point-- that was a rare event and atypical for a La Nina winter.

With that, I'd strongly hedge that we pull back our winter expectations. Mts will still get plenty of upslope snows, I'd be shocked if anyone east of the mountains (Roanoke included) breaks 10 inches on the year. I'd increase the risk of an more significant ice storm with low level cold lurking and a bad storm track.

In the near term-- we do have a few shots of cold air incoming, but they won't last long.  I don't see much to think we get into a pattern that looks anything like winter in our region. A cold front passes Wednesday and SOME data has hinted a shot of snow as it passes, especially to our north. Those events are RARE and I don't expect it to pan out.

Safe travels today-- big ticket weather event late weekend.

Everyone is likely about on the road now. The weather has been warm a few days, a couple cold and back to warm. This will continue. We've had the exact opposite of the pattern we'd need to get sustained cold. (Not that it's a bad thing in November, but often the November pattern does tip the hand of winter)

Keep an eye on the forecast for Sunday. Pretty intense storm passes to our west will place much of east coast in the warm and unstable sector. (AKA- late fall severe weather likely)

Good link to an article written by Wes Junker- He's likely the best forecaster I know- and it ain't that close from him to second. The article discusses what goes wrong and forecasting and why. Worth the read, even if you don't get all the science part.

http://www.washingtonpost.com/blogs/capital-weather-gang/post/why-are-snowstorm-forecasts-sometimes-so-wrong-part-one/2011/11/23/gIQA4ZfaoN_blog.html#pagebreak


Happy thanksgiving to all! If a pattern change comes- I suspect Dec 15-20 will be the NEAREST time we experience it.

Winter Outlook--2011-2012

I waited until November to get in some data and the data does really help me at all. My sneak peak talked about the QBO-- and I wanted to see the October number and had that drop continued, I'd feel much more confident with a colder and possibly more snowy compared to the normal numbers. With that, my confidence is a lower than normal because the QBO dropped slightly, not a deeper drop.

I really should make a glossary that explains all these QBO, NAO stuff-- if your curious feel free to shoot me an email.

Winter 2011-2012

Slightly colder than normal winter wide--
Snowfall- slightly below LYH to DAN , NORMAL ROA Valley, Slightly above NRV up to the Highlands.

Maybe a decent event of 6-10 inches region wide, the rest will be more in the 1-3 inch range, often mixed with sleet, rain and freezing rain. These events will do much better to our west, hence my logic of normal to even above in the NRV and Highlands.

Snow guesses-

LYH  15.5
ROA 19
DAN 7
NRV   28

Give me a range of 2.5 inches either way on the snowfall. However, despite my snowfall totals being pretty good the past 2 years, it's some educate guesses and some luck.

Temps- compared to average

Dec  -1.5
Jan -1.5
Feb +1

So,that's slightly below normal

Factors- weak to moderate second year La Nina, -qbo (still hedging it drops) longer term pattern of blocking  up north (-NAO and -AO) -PDO (Usually favors warmth, but in second year nina's tend to trend cooler)
AMO- favors blocking as well.

Storm track-this fall has seen quite a bit of coastal storms both via Hurricane tracks and general areas of low pressure. I'm hedging less snow because of a moderate SE ridge-- won't kill the warmth but will allow storms to take a generalized pattern of INTO TN, KY WV region and reform to our north along the coast. That places us in the slope storms of 1-3 inches. I do expect QUITE a few of these storms and once or twice when the -NAO and AO are extremely negative we get 1-2 decent events.

There are some early signs that our December cold pattern is in the genesis stage and the pattern may begin to shift NOV 20th give or take and the cold may be evident by late month. Considering tomorrow is Nov 5th-- we've had WAYY to many snows on December 5th in the past 10 years.

Cold rain with some flakes

Historic event on tap-- but nothing here but a fierce cold rain with occasional snow mixed in. I can see a couple time periods where it cools enough to be ALL snow with huge flakes falling. If this was Nov 28th- I'd be calling for a foot. (Blacksburg, Roanoke and Lynchburg included in this)

Places north of 64 (Stuanton) NE will have a HUGE event-- tons of snow and tree damage. I can see places getting 16 inches with only max accumulations of 8-10 with melting on the bottom. This will extend NE along 81 and curve into New England. This is literally, one of the biggest Octoboer snowstorms on record in the makings.

If there was an actual "snow meter" I'd have to raise it to 6.5

Two models, the GFS and ECMWF have had subtle shifts in the past 2 days-- one shifted east, one shifted west, both had a weaker storm. It seems like SLOWLY they are coming to an agreement.

It not locked in-- but late Friday evening rain should develop and once it becomes heavy it will mix with or change to snow. High elevations are at the best chances to see SOME accumulations but I'd not be shocked it even close to Lynchburg sees a coating. These storms are tough as it involves upper air energy diving our way and spawning a storm that forms JUST far enough south to throw back moisture into our region. While it's cold enough aloft- 3k feet down as modeled is just above freezing.

This could be a pretty damaging storm to trees up towards Wintergreen, Afton Mt and other places NE along the Blue Ridge Parkway.

If your nose has been twitching-- Could it be "snow" has been mentioned MAYBE in our region??

October snows are rare-- but no unheard of. Oct 1979 had a rather large event that dumped 2.5 inches in Lynchburg as heavy rain changed to heavy snow. Parts of the Blue Ridge- Skyline drive had upwards of a foot or more in that event- Drastic change as the temps near midnight were 53 degrees and 9 hours later we had heavy snow falling-- in OCTOBER.


We currently have a strong short wave ( upper air energy) diving in from the MN region and it spans a storm that spins up and on some modeled data shows rain changing to snow for our area. (Not ALL areas-- seems to be mainly rain S and E of Lynchburg). Time frame on this event is Friday night into Saturday AM.

Here are a couple snow maps-- the first is made by the GFS and shows a strip of snow along and east of the Blue Ridge-- 1-2 inches.
Next, the ECMWF has the storm more amplified and the snow is MAINLY to our north, but-- its a ton of it!

Wild stuff!

I'd guess that there is some type of "abnormal" even happening, but I'm not convinced we see here. Hot Springs has a good shot, up into the Mts of WV, PA and NE from there- if anything changes, I will certainly update.