Monday, November 25, 2013

November Rain

The big story SHOULD end up being the COLD November rain over a 36 hour period. Rain totals should be 1.5 to as much as 4 inches. Considering it's been dry, the rain is needed but is coming on worst travel week of the year.

Had we had blocking in the North Atlantic-- we'd be staring down a MAJOR snow and ice event-- instead the big story will be a Cold November Rain..

"It's hard to hold a candle, in a cold November Rain"

Did you know that Axl Rose started writing November Rain while in Jr High? 

The Bookend Problems. 

1. The storm should start as maybe a burst of sleet and then some freezing rain. Currently, the western regions of our area are under an advisory for the freezing rain, but it's predicted most areas for SOME ice. Cold air can be stubborn and despite that freezing rain without a cold air source is a self defeating process. (Freezing water actually releases heat, which sounds counter intuitive) And some pretty warm air will be riding over the top, (Surface temps will hold in the mid 30's but at 3-5k feet temps will approach 50)-- sometimes that last 200 feet are STUBBORN to warm up. So, while a trace to slight coating of ice is likely, we need to monitor for a longer period of ice tomorrow morning. Would not be surprised if most of the area ends up under an Advisory.

Chance of ice over .10 tomorrow.

Back Bookend: Ending as Snow-- If I had a dollar for every time a storm was supposed to end as snow...they are RARE.

However, this is a unique set up where we have a strong arctic front coming as the storm ends with some strung out vorticity riding along the front. Looking at the soundings, (vertical view of our atmosphere with temps and moisture) I think we do get a quick burst of snow. Most places will have 1-2 hours of gloppy snow flakes falling that melt on contact. I could see a line of snow developing that "coats" cars, trees--grass but it won't be a HUGE deal. 

WPC has our region under a 30-50% chance of seeing an inch-- depending on where you are located. The Mts to our west obviously do better. 

The Big Story will be "Cold November Rain"

Rain totals...

Nothing last forever, even cold November Rain...

Sunday, November 24, 2013

Arks will be needed for Thanksgiving Week

Social media chatter has continued about the big storm and possible snow.

Looks like the rain will start early Tuesday for most of the Lynchburg and Roanoke areas and it will POUR.
2-4 inches of RAIN very likely region wide.
Red are is OVER 3 inches.

2 possible winter precipitation events in this...

1. As it starts, cooler dried air will be in place with temps near freezing. A quick burst of sleet could transition to some freezing rain for a couple hours Tuesday AM. 
2. As the low winds down, colder air is filtering in behind and depending on that speed plus the upper air low, some model data suggest it ends as snow. Some model data says just light snow and flurries while others drop a coating to an inch or more. (Few runs of Euro drop 3-4 inches in both Lynchburg and Roanoke)

My take-- these lows with trailing upper lows are tricky and fickle-- would not be shocking if NO flurries fell and would not be shocked if 1-2 inches of snow on the backside. Let's play conservative as of now and go with NO accumulations, but ending as snow. Mountain areas will do a little better. 

Friday, November 22, 2013

Thanksgiving Snow Threat...???!!!

For those in social media world, there's been quite a bit of chatter about a possible SNOW event just before Thanksgiving.

The Cold is Coming...

A series of cold shots will be heading back into our area, the first on late Saturday and Sunday will be FRIGID. Temps most areas will struggle to get above freezing Sunday.

The Cold is Leaving...

Because we have no blocking (-NAO) the cold slides out to our east quickly just as another shot approaches from the west. It won't be WARM, but not the bitter cold air we will have Sunday.

The Storm Approaches....

More cold air is zooming in from the west as an upper air low literally moves across the country. Timing is key to when the cold air gets here and how much interaction takes places between the two jetstreams.

Options include:
1. Out to sea with little rain.
2. Up the coast but little or no cold air. (big rains)
3. Cold air arrives a smidge late..(rain ending as snow)
4. Storm is a bit slower and snow threat increases.

My current take:

I'd lean somewhere between options 2-3 where we get a nice rainmaker before the cold that COULD end as a flurries or snow showers, with an outside shot of a coating to an inch. Areas to our west in the Mountains should have their first snow of the winter and ski season will get a nice early season boost with the snowfall and NICE chances to make snow.

Looking forward...

My winter outlook may be on the ropes early. I went extremely low on snow and there is a decent chance we put a dent in that total before December 10th or so. Some higher latitude blocking called EPO and WPO are forcing things colder than most had thought. Most people expected a rather warm November and we should end the month 3-5 degrees colder than normal. This trend will continue through the first 10 days or so in December with perhaps a shot or two of snow in that time frame. (read that as a SHOT or two, not a promise :))

Will also be a challenge to get my +2-3 in December with the first 10 days likely to have a decently low of maybe -3 to -5 for those days.

With the Holiday week coming up, I will update more frequently as this storm and cold unfolds. As of now, a decent rain event seems likely with .5 to maybe 1.25 inches of rain falling that could end as snow in the Lynchburg and Roanoke areas.

Thursday, November 7, 2013

I feel obligated to post...Snow threat?

It would be very fitting since I went a warm, dry winter that winter kicks off with an event that completely ruins my winter forecast before both the winter solstice AND meteorological winter. (December 1)

Many of you may have heard a little chatter from various outlets about a storm literally 7-8 days away. Speculation is good, if it's presented as speculation. However, what I fear is blogging has turned into Black Friday shopping where people get earlier and earlier alerts and the public can't gauge the difference between an actual threat a couple days out and just some fun chatter about crazy model outputs.

What are the models showing?

The models are showing some VERY unseasonably cold air moving in out of Canada. At the literally perfect time, a short wave digs in and creates a storm. Now, some model data shows a "Alberta Clipper" type event and other blow it up via "closing off" the upper air low and there is a HUGE event. Some of the data has "fringed" our area with the blow up and others have made it a huge event.

The obligatory snow map from the most extreme run..

6-12 inches in our area, with a lot more just north and east.
What do you think will happen??

This falls under the banner of-- just keep watching. What we know is this: 1. Some colder air is heading in our region for a visit and likely a short wave. My guess is that the cold air won't be as cold as progged and short wave will be much weaker and well north. Hence, the upslope areas well north and west of our area could get a decent upslope snow and some lower lying areas in WELL NORTH of our area could see their first flakes of the year. 

Even if the STRONGER colder air and upper air low cuts of, it is well favored that any extreme event (which  I've stated is unlikely) would happen WELL to our north.

Friday, November 1, 2013

Winter Outlook 2013-2014

I could give you the blah blah of why I don't update, but let's be honest-- I'm a winter weather guy. Yes, I talk Hurricanes and Severe on FB when it happens but my intense forecasting is about winter.

So, if you are NOT a winter fan, you will like my update.

Roanoke, Danville, Lynchburg

5 inches or under of snowfall. Mountain areas see more, but still well below normal.

December temps 1-2 above normal
January 2-3 above normal
February 1-2 above normal.

Not much data I see supports lasting cold or great storm patterns. I like to see how Eurasian snow cover trends in October as the final piece and that did NOT look good.

My point of going so low is to point out that this will be a boring, mild and likely dry winter. I could of hedged at 8-12 inches and hoped for ONE bigger event to save the day. These are ALWAYS possible (not 12+, but a fluke 4-8 inch event)


I think the Arctic Oscillation runs Neutral to positive most of the winter. ( Cold is bottled up on other side of globe, tighter wound Polar vortex that keeps cold air away)

Negative PDO - leads to trough on West Coast and Ridging in the east.

Storm track well to our west, and when the pattern "relaxes" more east is still into the Ohio Valley reforming off the Delmarva.

If I'm wrong-- there are ways to get stronger discharges of cold air into the east (-EPO) at times. I'm hedging it won't be.

Also, you CAN get a fluke snow storm-- but I'm hedging against that too.

That's all I got to say about that.