Storm on track-- Cold more cool, not bitter. **Edit to add photo**

I must say that I just hate this storm coming our way-- so many good things about it that simply can't deliver for many reasons.

A strong southern short wave spins a storm up in Texas and it heads east, However, the block causes this energy to dampen out and the storm loses its punch at our doorstep. A second piece of energy swoopes down from the Pacific Northwest and regenerates the storm-- but its just a little too late for our region.

As of now, I'd predict 1-3 inches from late Monday into early Tuesday.

We are very cold for a couple days after that, and then get a brief warm up before another arctic surge.

Map from the HPC--- precipitation outlook. Note the minimum over most of our region. The Southern low dies our, it meanders off shore, to be energized JUST to our north. The ridge out west isn't large enough to cause any digging of the second piece of energy to drive it more south. Looks like a DECENT event in Philly and a LARGE event for NYC to Boston.

Next update Sunday afternoon.

Complicated snow event possible-- Cold still coming

The cold is still on tap as discussed in my last blog. As usual, the extreme version won't be as likely-- much much colder then normal, but some of the cold trickles into the pacific northwest and the core of the cold sits in NW Canada sending pieces down towards our region. Doubt we get below zero unless we get a quite the snowfall but lows and highs both average 6-12 degrees below normal for the next 10 days. The warm days will reach 40 at best and the cold days will struggle to reach freezing. For a reference point-- the average high for this time of year is about 44 and the average low is 25.

Snow wise--

As an arctic front drops through today-- a piece of vorticity swings to our south and and could bring some flurries or even a dusting of snow. Places along i40 in NC could see a couple inches from this event.

The Big Show is far from decided.

Set up- Cold air settles over the region and a strong shortwave heads east from the south Cali coast. Low pressure forms over the deep south and heads east. Because of the strong block over the NE--this original short wave gets sheared out and our low doesn't deepen and loses the moisture transport from the Gulf of Mexico. As a result, what was putting down over an inch of liquid over the TX to GA areas is suddenly very dry.

A second short wave races east from the Pacific northwest and at some point re-energizes the storm.The quicker this happens, the bigger of a storm we get.

How much snow is possible?
If its a smidge late-- we get a 1-2 inch snowfall.
If its a tad faster- 2-5 inch snowfall.

I'm not willing to commit either way at this time. Both pieces of energy are just coming ashore on the west coast and as they get close with better sampling data for the computer models, we should have a better handle on this.

Pattern developing will be EXTREME-- this time it's More Than Words

The long range forecast reads like this--

Cold, Colder and Coldest--

My winter outlook called for colder than normal December ( OK, kinda whiffed on the 5th coldest December)
COOLER in the first half of January leading into moderation. Someone Que the Price is Right lose music, because I'm going to be wrong. Very wrong.

We are about to have an arctic invasion, perhaps one not experienced in 25 years. (Jan 1985) The next two days COULD get to near normal before the bottom drops out.

Why? The perfect global set up to drive cold air over much of the United States. The first wave of cold air begins to filter in later this week with even a chance for a few flurries and snow showers. It will be cold, but not anything historic.

This map is valid for the 13th at 7PM--that's a cold look.(Temps reflected are at 5k feet) Would translate into highs in the 20's to maybe low 30's and lows as low as 10. 

Preceding this cold COULD be a possible snowstorm. Timing is huge to when the cold air works in VS the energy coming from the current California Storm- if the cold is a little to quick it shears out the energy and we get nothing. Also, some of the data has wanted to have a SMALL window where the low works up to our west . Hard to see that as a possible outcome, as the most likely way we miss this event would be sheared out and to our south. 

This model called the GGEM shows a possible solution to how we could get some snow. The next frame moves it out to sea, so its not a HUGE event, but would be a 2-4 inch type snowfall. After this event, we have a couple frigid days (Map reflected above) There could be a BRIEF warm up and then the "Motherload" of cold air is about to move into the US. 

That BIG L over Wisconsin is along the leading edge of BRUTAL cold air--and it would reach the East coast about 36 hours after that. This could be the coldest air mass in 25 years. (Thanks to something called the -EPO) Map valid 1/15/11 temps reflected again, at 5k feet. Note the -30 reading up in Canada. 

Snow threats--Maybe a few flurries or snow showers Friday, but the first threat is Monday/Tuesday Next week-- next, with an arctic blast like that I would guess we could get a quick coating and then we sit in the cold (Day 11). Maybe around the 20th as the pattern starts to relax something is on the table. 

Where do we go from here??

As we close out December with ONE very warm day, how does January unfold? My original outlook expected December to be a colder than normal month and the COLDEST of all three winter months. January was to start cool--but end warm and February was to be warm.

December was COLD-- top 5 cold. Most expected a cold December, just not THIS cold. I'd not have expected 6-12 inches of snow region wide, but that's the hardest prediction to make.

At this time, it does appear that we will rebuild the -NAO (Greenland Block) starting early next week and some threats will be in line after that.

Attached is a map that shows heights rebuilding into Greenland (Good sign if you want more cold and BAD if you hate it) Recall that we never got a BIG storm because

1. Lack of Sub tropical Jet due to moderate la nina
2. Lack of PNA ridge-- normal "lack" in la nina winter. We had the Greenland block retrograde into Canada and link up with the lack of PNA ridge, leading to our BIG Christmas snow ( HUGE event in NC and than up the coast)

Note the ridging into Greenland-- eventually  cools us down and the baggy nature of the green colors over the SW tells us there is some energy heading east. Off the cuff, this type set up leads to more of an icing threat compared to snow. (Note-threat, not a forecast)

New Years Weekend starts dry and warm and a cold front comes through New Year's Day NITE--temps being to cool and we wait and see how the pattern sets up for January.

In the FWIW department-- I was reading some research about the EXTREME Greenland block and -AO we had in December. Blocks that extreme are rare, but when they do happen, they usually repeat themselves later in the winter. So, my warmer Jan and Feb COULD be in trouble. 

Should of asked for a waffle maker this Christmas--- (Threat growing for MORE significant snow)

**Noon Update**
I like the 2-4 inch call after examination of the noon data. Original Call stands.



Wow, I've heard a few forecasters describe this line of work as humbling. Despite being a local guy who does this for fun, after following these models for 10 years and even taking some classes, days like this make me completely understand why this is said. When dealing with Mother Nature, Chaos theory still rules the day.

We've gone from
2-3 days of thinking a BIG snow was possible to
24 hours of thinking an inch was the MAX
to
Currently thinking 2-4 inches is once again possible.

WHY??
 Computer modeling is amazing and addictive. Earlier, we had talked about a "phase" and how the phase had a 6-12 hour window to happen at the right time and at the right place, or the storm will still form, just well to our north and east.

Today, the noon model data came out and some had formed the storm earlier--but the powers that be (Hydrometeorological  Prediction Center) stated that the data had assimilated incorrectly and was wrong. The ECMWF (Again, the proven most statistically correct model) Did not form the storm far enough south and west to change my thinking from **possible** coating to an inch, with only Hampton Roads area getting a decent event.

Late day, the american models that run STILL had the event in our region.

As of 4 am, Christmas day, as Santa is dropping off presents on the west coast, Every model states most of the Central and SW VA region sees a decent snow from this event. All data points towards 2-4 inches ( One could argue for 3-6, but let's start small and stay with it)

Basically, the 2 phasing jets-- the subtropical has remaind a SMIDGE stronger and polar jet has dampened out the first piece of energy in favor of the second piece just behind it and the low begins to explode just to our south and we get a late evening, early Boxing day snow.




Current Radar for Lynchurg and Roanoke.

This should reach the ground towards sunrise. This first batch will slide east with our original coating and a second, stronger area moves in from the SW after 1 PM-- most of the region has snow falling by 4 PM.

General snowfall ideas.

Mt Areas west of 1-81 (Entire event, including upslope snows)
6-12 higher elevations, 3-6 lower, south of the NRV and 2-4 lower elevations north of there.

2-4 Roanoke, Lynchburg--and all the small towns in between.

3-6 Martinsville, Danville, Farmville and Charlottesville.

Hampton Roads 6-12 some mixing issues, 6-12 over most of Delaware with Mixing issues near the coast and 6-12 for my Two favorite nephews in Broomall, PA. (Coastal regions have higher shot both mixing and the highest totals)

Will update later today, as the more intense this storm gets--the better chances we have of getting the higher end of these numbers . This is a "white of the eyes" storm-- won't know the full impact until we see the white of its eyes.  Challenging forecast-- Merry Christmas!

**Quick 7am update before my kids get up to open up presents**
1. It is currently snowing--first wave made it in as expected. Won't be more than a coating, but how awesome is light snow Christmas morning
2. Based on WV loop and some other model data, I'm concerned this becomes a much larger event for our region. The MID runs are spitting out over 6 inches of snow. Let's wait until the on hour model data happens, but this could be a MAJOR event.

Attached is the precip output from the GFS ensemble means--the .75 liquid basically runs right up to highway 29-- the operation runs up to .5 precip. This would yeild 5-8 inches of snow across the region.

Stick a fork in this one--because it's done!

Bye Bye Christmas storm-- Hello, easy travelling.

If you live by a modeled forecast, you die by the modeled forecast. A model called the ECMWF has proven for about 10 years to be the most reliable forecasting tool. However, it will have speed bumps in the road. Just last week it tried to blow up a late weekend storm and brought snows from NC to New England. Again, this time the same model had an EXTREME set up where heavy snows would fall from SC to New England. I have no issue with the National Weather Service and other media outlets reporting this possible storm because of the HUGE impact on Christmas travelling.

You may ask why? I really don't like the old phrase-- Being a weatherman is a great job because you can be wrong half time time. Reality is, people who say that know nothing about the science of meteorology. Some brilliant people have made great advances in this field-- and its truly shown when you look at the data. When you can't control the factors and can't get exact data at the exact time for all the layers of the atmosphere-- it becomes rather complicated. Literally 6 hours difference and a couple hundred miles on the short waves (energy aloft--they often show you picture of spinning clouds if you pay attention during storms) would have created this monster event.

Last winter was EASY-- we had a very strong sub tropical jet and extreme blocking. VERY easy to get major storms and most were modeled out well far in advance. This year, a La Nina, the challenge is greater because rather then having that strong sub tropical jet, we are rely on "phasing" because the sub tropical jet is a little starved for moisture.

The term "phasing" means the jets work together to create a storm. The challenging aspect is that if they phase late--even by 12 hours, they can cancel each other out, move the storm track well away from the threatened area and other factors like that.

There could still be a period of light snow and flurries Christmas day, but this big threat is basically dead (Could see a coating to an inch Christmas day). Cold lingers the remainder of the week and December finishes top 5 coldest month ever. Lynchburg has a shot at the coldest December on record. From there, the pattern breaks down -- the model data hints it may be only temporary before it reloads cold but I'm not willing to budge (yet) from my thoughts that by mid January we are rather warm and February is even warmer.

A buzz is in the air

We've been on this storm a few days now--and finally, a solution could be in reach. The storm that has battered Cali with 10 inches of rain and 13 + feet of snow in the Mts is heading east. At the same time, some energy is diving in out of Canada and will phase with the Cali storm energy near the SE states.  IF, and IF this phase happens at the right time this will be a historic storm. Even if timing is 6-10 hours off--we could get graze rather than the full impact. On top of the possible snow--winds will be strong for a long period of time. Beach erosion will be rather bad. Winds rush from high pressure to low pressure...and  there COULD be a 1035 HP over MN while a 970 low sits just east of Cape Hatteras. You won't see 65 MB difference in that time space often other than from a Hurricane.

If the phase timing is off-- the further south and west you sit, the more likely you don't see much snow.

Would start late Christmas day in VA and slowly move northeast-- and really last well into Monday with the winds. Snowfall would meet Winter Storm Warning levels--which is 4 inches. And, the B word is possible, especially those nearest to the ocean.

Map from the Extreme model version--- this is 7 PM Sunday evening. (Miserable Eagles- Vikes game)
A low pressure THAT strong sitting there would have snow falling from Philly down in to NC-- with heavy bands and strong winds.