Sunday, January 27, 2013

Light ice event..

** edit at 5PM ***

NWS has upgrade the entire region to a Freezing Rain Advisory.

not a very WET system as total precipitation will be maybe .10 to .15, but colder ground temps and surface temps in the upper 20's and low 30's will make for some NASTY road conditions through mid to late morning.

National Weather Service issued a winter weather advisories for all the counties along and east of the Blue Ridge. The freezing will be light-- maybe .10 total falls out the sky but with the colder temps as of late and LIGHT stuff falling it has the makings for a disaster in the am. Half the issue is that folks may not see the ice on their driveway, get on the road and there is just a few slick spots here and there. There was an event in December of 2007 where there was .02 precipitation and the road were just a disaster.

Side note-- If I were king of the world, We'd of had advisories everywhere Friday BEFORE 10 am. It was a situation with the cold temps, even an inch would make a traffic issue-- and that's clearly what we had Friday.

Tomorrow-- The freeze line appears to be south and East of Lynchburg. With that, I'd push the advisories into Lynchburg, Campbell and maybe even Appomattox counties. Better safe than sorry. :)

Be safe tomorrow morning. By 10 am, we look to be all good again. Expect school delays.

Thursday, January 24, 2013

Snow Event

This has not been a fun event. Cold temps, dry air and models all over the place. And, being all over the place varies snow from 1-3 inches. It's not a huge storm and never really had high side potential. However, I take time and put my best effort into these forecast.

The air is very cold and dry, the upper air support is meager and weak and the energy is transferring to a coastal low that will scoot away from the coast. It's a losing process all around.

I've made minor changes to my ideas. 2-5 NRV, MT Empire and those areas. I think sleet pushes in down south towards Danville, Martinsville and South Boston eventually. Roanoke gets around 2 in the city proper and east towards LYH is about an inch region wide. However, some of the high resolution models are picking up on a decent band of snow forming near the NRV and pushing east just along and south of 460. So, Roanoke and Lynchburg in this path. If THIS happens, a quick 2-3 inches is possible in those regions.

Friday, January 26th 2013

Will update early AM if needed, but just know that MOST areas east of Roanoke are in the ONE inch side of things. Be safe, even if it's a dusting. Colder temps, way down near 10-15 tonight will make the roads rough quickly. It's my experience that either extreme slush list last week during the HEAVY snow or lighter snow with cold temps makes for the worst driving.

Wednesday, January 23, 2013

Flurries tonight-- Accumulating snow possible Friday

The cold has arrived and we are sitting at a chilly 14 degrees this AM. If we can get through today in Lynchburg below freezing, we may not touch freezing until the weekend.

A fast moving clipper system comes through tonight and could drop a few flurries. Some places- especially north of Covington to Amherst line may see a quick coating. Not a big deal. The problem arises in the fact that this system is a bit close to our Friday system and drives our reinforcing cold air a little further south AND inhibits our storm Friday and may decrease our potential snow.

The "magical" ECMWF- which did decent in our area on last weeks storm but was WAY to far north with the model showing snow into DC when it didn't really make it north of Charlottsville shows a nice 2-4 storm east of the Blue Ridge with maybe up to 5-6 west. The rest of the model data is showing as little as a coating with maybe up to an inch or two.

As of now, I'm splitting the difference and going 1-3 East of the Blue Ridge and 2-4 west, south of Staunton. We should have a better handle on this later tonight and into Thursday.

The cold will continue into early next week before a brief break.

Monday, January 21, 2013

Cold week on tap, maybe some snow LATE week.

The cold is coming. It's not horrible, bitter arctic- but it will be a break from our really mild winter. Highs in the mid to upper 20's and lows in the teens. We are being spared with the cold push not driving down deeper than the mid south, we are not getting in the core of the cold. Still, bundle up, watch your pets if they are outdoor and get that firewood inside!

Don't rule out flurries at certain times either tonight with the cold front or Wednesday with a clipper going to our north. And yes, Granma's cabin in the Mt's will get a little more.

I'm watching a system for sometime in the Friday time frame. Models are all over the place with the furthest track south passing right over us to the most north going about the Mason Dixon line or so.

If it tracks at us-- we get a quick hit of snow that ends as ice.

If it tracks near the Mason Dixon- We get a quick hit of ice that MAY end as rain.

Will update later as needed.

Friday, January 18, 2013

Post storm wrap up

Our storm came off as expected with NOT a bad forecast, but certainly a glaring snow hole from parts of Bedford county into Amherst as the "mega band" formed just a smidge south and missed some areas.

From WSET-- Total snow estimates.
This type of system, this can be expected. I tried to state several times that when the band forms, that there will be winners and losers. The model data was clear there would be a transition of the band as it progessed east and the data was off by maybe 25 miles on the formation. For those who got under it, it was pretty incredible. 

I knew something was up when people in Bedford and Amherst were telling me it wasn't snowing yet and I was getting clocked. This is a snip from the airport weather station. I assume the change over was the same time. We had snow mixing around 4:45 and it was mostly snow by 5. With that assumption, .70 liquid fell as snow. Between the warm ground, marginal air temps, etc it was 3-4 inches for those who were under the heart of the band.  That's a 5-1 ratio. A normal snow has just above 10-1 ratio.  Incredible flake size-- flakes of 2.5 inches across and maybe even 1/8 of an inch think. As a guy who tracks and chases snow, I don't know if I've ever seen flakes that big. The snow had huge divots like a golf ball as it accumulated. My assumption was we'd get  7-8 to 1 ratio on the snow fall. Had that verified we would of have 5 inches or so.

Further, as the band moved south there were a couple lighting strikes, one near Concord and the other down towards Altavista.

So, I'd grade my outlook a B or so. Those big bands are hard to forecast and getting the ratio wrong as well makes less than perfect. I think the overall flavor was pretty good.

Nothing big on the horizon. We will have few pretty cold days next week but nothing extra ordinary. 

Thursday, January 17, 2013

Here comes the BOOM!

All overnight data looks as good, if not better. 

I was tempted to upgrade west regions to 8-12 and east to 4-8. but going to resist as of now. Just know that   literally anywhere the extreme banding sets up has potential for more than forecast. Brief map. West of green line is 6-10 with the best banding places getting 12. East is 3-6 with local spots up to 8.  I highlighted a couple spots that I think can get those higher amounts. West of the Blue Ridge-- SW side of NRV down towards Hillsville and the Mt. Empire. East of the Blue Ridge-- Northeast of Lynchburg EARLY may catch some good banding as the set up and then later in the evening Danville, Martinsville and South Boston may catch the better rates longer.

Final Call to "grade me" on. 

Changeover Times Estimates.  

As the stronger lift moves in, there could be a couple hours of mix of snow and sleet in heavier burst, but eventually it will be snow and heavy stuff. If we flip sooner, watch out.

NRV, MT Empire - North up, bending east to north of Amherst -81 between noon and 2.

Roanoke- Lynchburg. 2 and 4 PM

Danville-Martinsville- South Boston 4 and 7 PM.

Strong possibility of Thunder. Best hour rates may be 2-3 inches for 2-3 hours. Possible tree damage due to wet ground and heavy wet snow.

Add me as a friend on FB- Keith Huffman

Twitter- Lynchburgwx

No blogs likely, FB and tweets.

Wednesday, January 16, 2013

Quick update-- is this legit?

Early evening thoughts--

This has the potential to be a very fun and memorable event. Doubt we set any snowfall records, (Maybe daily, need to check) but 7 inches falling in 4 hours would be good fun. 

However, tough system to track and as I've stated- even if it plays out on as depicted on the best models for snow, there will be winners and losers based on where the banding sets up. So, 3-6 outlook may see YOUR backyard get 2 but many others get 6-7. It won't be a uniform snow total. Banding isn't really modeled well- so that's another forecasting concern. 

Also, most places start as rain-- and it won't be that cold. So, some folks will start whining about the weatherman blowing another. I'd recommend following Sean Sublette and Jamey Singleton on FB and Twitter for other resources for current trends on the weather.

If it were up to me, I'd of gone warning region wide. 2-4, while very plausible is on the low end. As of now, All the counties WEST of the Blue Ridge are 4-8 and east are 2-4. Further, there are Winter Storm Warnings to our West and North, and watches to our south and east. To single out 4-5 counties East of the Blue Ridge is confusing and with the fast onset and potential for more, it's my belief it was the more prudent choice. With that, if we all get a couple inches east of the Blue Ridge, they'll look great.

Things that can go wrong-

This is being driven by that upper air low I graphed yesterday. The exact strength, track and speed play a huge role. If it ends up a tad weaker and faster-- we won't see as much. If it's a bit stronger and slower-- we could see a foot. The point being, while I am optimistic about this event there are more factors that we can't control in forecasting. So, if you want snow-- hope that ULL goes a little slower and stays closed (stronger) as long as possible. 

I'll do a full update later this evening with an actual map. Busy day tomorrow trying to work before the snow starts, but I'll tweet and FB all day as needed. I don't foresee any major changes in my 3-6 east and 6-10 west because I'd rather massage up if needed than forecast a foot and have the average be 2 inches. Just keep in mind that "potential" is certainly there. 

Twitter-- Lynchburgwx

FB- Keith Huffman-- Subscribe or friend me as I use hootsuite to update FB and twitter at the same time. 

Some of the snowier models kick the ROA and LYH areas to snow early afternoon. Be ready for bad travel, school closings and a general mess. 

The exact speed and strength of that "closed upper air low" is a  huge factor.

We could be in store for a WILD ride...

What a RAPID shift yesterday--

Winter Storm watches in effect EVERYWHERE west of the Blue Ridge. My hunch is if the model data holds serve, they expand it region wide. 

There are off hour runs of the GFS and NAM, both are still the crazy snow changover- but timed a bit different. GFS is over to snow much faster-- but the event is faster. NAM waits a while, but last longer. In the end, results are about the same. 

If you want a "first guess"

Areas west of the Blue Ridge-- 5-10, high elevations may see 12. 

East of the Blue Ridge- 3-6, local spots up to 8. 

Going to be some issues-- change over will happen quickly in the NRV and Highlands- and then slide east. If you are out when it changes, roads will get bad QUICKLY. If nothing changes on the model data, it will be ROUGH travelling. Further, While the NAM radar looks impressive, these band have a life of their own, You may see and inch or two and your brother 40 miles away sees 8. 

Here are two simulated radar shots from the NAM, (slower with the system model)

Yellow is what you often see under thunderstorms-- and once you get under the yellow, it's likely snow. 
First shot is at 7 PM tomorrow and second is 10 PM. Mega band just ROLLS our region. 
Per this model- 7 PM-- just getting crushed NRV ROA up and down 81. 

And three hours later it rolls through the rest of the area. Snow rates 1-3 inches in that band for 3-5 hours. 

Tuesday, January 15, 2013

From Bat Signal engaged

**Euro is on board, not as spectacular as the other models. However, LYH went from about  quarter inch of liquid to almost an inch. Getting the 6-8 inches was a tall order. I'd be thrilled with a 1-2 inch snowfall Thursday**

To Bat out of hell ..

If the Euro jumps on board, you will hear BIG time honking Wednesday AM about snow Thursday.

Will update this when ECMWF comes out.

The Set Up....

Lost in the inches of rain has been a slow, meandering upper air low coming out the southwest. Traditional thought is outside of 3 days, hard to get 2 separate systems back to back that close.

So, a few model runs here and there have been showing the second just sneaking in a bring a rain to snow even and they've been dismissed. As we've moved closer, the southern ULL has held together and is modeled stronger. The temps are initially too warm, but the ULL cools the atmosphere and shows the system going from HEAVY rain to HEAVY snow. Often, if model data shows a cold front pushing in and a switch from rain to snow, they struggle. However, getting a vortmax in the right spot is a GREAT way to get that rapid shift.

Until-- the model data mid and late afternoon shifted more towards a possible snow event and so far ALL the models have come on board with rain developing Thursday and then changing to snow-- and then DUMPING snow for 3-5 hours. In that 3-5 hours a GOOD snowfall could happen in the lines of maybe 3-10 inches. These are tricky events, and with the type of banding some places may only get 1-2 inches and other 8-9.

The cool thing is because of the ULL, MUCH of VA, down to even the coast CAN cash in on some snow.

The pictures..

Here is the 500 mb low-- these are often shown by mets on TV-- these are the upper air energy that help form and enhance storms.

500 MB low, goes negative. (tilts NW to SE, common in stronger storms)--heads off the NC coast, perfect for VA snows.

NAM snow map-- NOT a forecast, but snows potential. Purple is 7-8, RED is 10+

Friday, January 4, 2013

Can you get a January thaw

When it was NEVER frozen??

Next week is going to be NICE-- VERY nice.

This weekend will be seasonable and very nice. Next week will heat up to have some days well into the 60's.

However, a term we used quite a bit last year called a "sudden stratospheric warming" is about under way. What this does is breaks down the polar vortex and pushes the cold away from the north pole. This will be underway over the weekend. Lag time before impact is 10-14 days. So, pattern change begins Jan 15th or so but should take another 5 days or so to adjust to our region.

What to expect??

Hard to say looking 2 weeks out, however if we want decent snow if this pattern comes to fruition this may be our best shot at a wintry couple weeks. The cold air seems to start in the plans and mid west and then build east. Tough call, because the last cold snap was more west based and built east. This seems to have a better set up with what is called "cross polar flow" meaning the air is coming from the coldest regions rather then last time where it wasn't SUPER cold.

Can this fail??

Well, the SSW is a lock. The only issue we can see with these is the cold goes to the wrong side of the globe. It happened last year. However, the arctic oscillation hit -3 in December and it seems to be heading that way again. (stats show that is likely). That should being some cold air to our side of the globe. Next issue is getting the fully into the east coast region-- which should happen, but not till after January 20th.

I will update late this weekend.