Early Saturday....

>> Saturday, February 18, 2012

Just wanted to put up a quick post about our incoming storm system. Interesting to see both the Flood and Winter Storm Watches hoisted for the system.

After skimming through the overnight model data, not a ton of changes I see except for it appearing the southward trend we saw yesterday appears to have stopped. One other item is that the system continues to slow even a bit more, and it might be late tonight before the rain moves in for many places.

As colder air moves in tomorrow, the rain will kick over to some wintry precip from north/northwest to south. The best snow opportunity for northern NC will be from later tomorrow afternoon through tomorrow night.

I like the chances of northern NC (roughly along and north of I-40) getting some snow on the ground. I especially like the chances now that it appears more and more of the precip will extend until after sunset tomorrow.

Temperatures will fall into/ through the 30s tomorrow into tomorrow evening with snow becoming possible from north to south as colder air aloft moves in. There will probably be a period of time where we lose the moisture in the snow growth region aloft, but indications seem to be that lift will again increase around tomorrow evening in many areas as a secondary upper level impulse moves in.

For those areas along/ north of I-40, I am not going to hazard an accumulation forecast just yet. I want to see how the trends unfold today.

For the southern Piedmont, I think any accumulations of significance will become difficult to come by. However, I do certainly think there is some chance of some flakes flying before the precip ends. It would take more southward shifts in the modeling to put this area into the decent accumulation chances area.

Up in the mountains, especially the NW NC mountains, this could be a pretty big deal. It would not surprise me at all if some of the spots that really hit the jackpot (higher locations) exceeded 10".

Unless some drastic shifts take place, I fully expect winter weather products to be issued for northern NC, likely including the Triad and maybe even parts of the Triangle area.

By Monday morning, especially for the areas I-40 and northward, travel could definitely be pretty tricky as temps will be below freezing.


Afternoon update...

>> Friday, February 17, 2012

I've skimmed over the 12z model data, and at this point, I see nothing to make me change my ideas from what was put out this morning.

Sure looks like the precip will linger around long enough Sunday (due to the secondary vort diving into the backside of the system) to allow the cold air to spill into a portion of NC enough to give some wintry precip by later Sunday.

I still think there is certainly the chance that the ground gets whitened in some spots from roughly I-40 northward, and there could even be some minor accumulations south of there.

Ground temps are warm, and I still have some concerns about moisture vacating the snow growth zone (you must have moisture getting lifted up into the region aloft colder than -10 C to get snowflakes to form....if you don't have that, you don't have snow...you have some other type of precip).

But all in all, this is an interesting system to watch.

The 12z European actually came in with more snow than previous runs across NC. In fact, at face value, it's a pretty significant winter storm north of I-40 with some mainly light accumulations down into southern NC.

So we will see. Still tons of moving pieces.

Here are a couple of snow accumulation charts from the previous run of the RPM. This is as close to my thinking as anything right now I suppose. Notice that parts of Kentucky get hammered.


Challenging weekend storm system...

Here is today's edition of the video. The entire video is focused on this weekend's storm system. Give is a look. Still a ton of question marks, but a trend has been toward a slower, colder scenario for parts of the region....

After a foggy start for many in the region, our Friday weather will be nice with a good deal of sun and highs close to 60.

Weekend system...

A couple of trends on the modeling over the past 24 hours. First of all, the entire system seems to be slowing down a bit. That will mean we will likely be able to hold off the rain for much of our region until after sunset tomorrow.

The other trend is a more pronounced push of cold air during the day Sunday, from north to south.

When you combine those two trends, the result it a better chance of at least some wintry precip in parts of North Carolina by later Sunday.

I will say that if the GFS is correct, you can largely forget about any significant wintry precip outside of higher elevations. However, most of the other modeling is giving parts of northern NC, at least down to around I-40 or so, a chance.

So, at this point, I think Sunday will be a day where piedmont temps start off in the 40s with rain, and then as the colder air bleeds in, temperatures aloft and at the surface drop, giving a chance of the rain changing to some type of wintry precip from north so south.

Hoe far south depends on how long the precipitation lingers before exiting.

One thing to note....at least on the European, Canadian, NAM, and RPM, this is not a cold air chasing the moisture scenario that so often doesn't work out around here. This is a separate disturbance diving into the backside of the system that keeps precip going after the cold air is funneling in. See the image below and note the disturbance in western Tennessee.

Another factor is the potential loss of moisture on the dendritic growth zone...I discuss that in the video.

So, interesting to watch. Probably not a huge deal for the piedmont, but I sure wouldn't be surprised now to see the ground whitened in some spots outside the mountains (mainly I-40 northward) by Sunday night.


Afternoon update...

>> Thursday, February 16, 2012

Interesting to note the 12z Canadian is similar to the 0z run (I shared an image from this model on the social media channels this morning).

The 12z European came in with a little bit of a colder solution....one that would indicate a chance of a little snow on the ground along and especially north of I-40 Sunday.

The 12z European model is in excellent agreement with its ensemble mean with our system. Interesting.

The southern piedmont would need a couple of more model shifts south to get into the snowy game, but the chances are certainly alive for northern North Carolina.

European operational 72 hours....

European ensemble mean 72 hours...


Showers today.... big weekend system...

I encourage you to watch today's edition of the video...most of the time is spent on the weekend system.

After some fantastic weather yesterday, we will have some showers at times today with a lot of our highs in the 50s. The rainfall amounts don't look too terribly impressive with this system.

Tomorrow looks fantastic with sunshine and highs in the lower 60s in many places.

Weekend system...

Please see the video...I spend almost the entire video discussing the weekend system in great detail.

Our weekend storm system appears as if it will be a big-time snow producer for the mid-Atlantic region. The Virginias might especially be the big winners in terms of snow.

There are still some details to be ironed out, but the general idea for the Carolinas is that rain spreads in by late Saturday or Saturday night and continues into much of Sunday.

The system could end as some snow certainly in the mountains and maybe the northern foothills and VA border areas. But for places like Charlotte, Raleigh, the Triad, and South Carolina....the system looks to be just a bit too far north this time around.

Now I will caution that we will probably need to make some more adjustments to the forecast over the next couple of days.

For snow fans in the Carolinas....it's a shame it doesn't appear this system will work out for many folks. Looks like a good one.


12z updates...

>> Wednesday, February 15, 2012

With the 12z runs....

GFS still looks way off. It destroys the southern piece of energy way too quickly, and that weakened disturbance kicks out way faster than other modeling. This puts the GFS back into the camp of its 0z shenanigans....driving a low pressure right up into central NC.

Canadian is slower and stronger with the southern piece of energy.....it only weakens it as a 'kicker' dives in out west and forces it quickly east. The result is a broad low moving from the northern Gulf to a decent amount off the Carolina coast. No precip makes it north of southern VA on this model. While not much, there would likely be a bit of snow on the northern fringes of the precip shield.

European model holds the intensity of the southern piece of energy pretty well but has little phasing with the northern branch. Result is surface low from near the mouth of the MS then to Charleston and then east of the OBX. This solution would likely have a little snow on the NW side of the precip shield.

UKMET looks stronger and further northwest....can only see in 24 hour increments though. This looks like rain for most in our region.
Bottom line.....mountains are in the game for some snow....possibly...possibly some snow as the low moves to the Carolinas coast elsewhere on the northern fringe. I don't think the GFS solution is likely.

At this point, I think it's looking like it will take a Hail Mary pass in order to get things to line up for much in the way of snow for the piedmont and upstate. Not impossible, but a whole lot of things are going to have to line up and trend in the right direction, and that's looking increasingly difficult to do.

However, lots of moving pieces here, and like I said this morning, expect plenty more model madness over the next 36 hours.


Nice weather today... question marks for our weekend system...

Here's today's edition of the video....give it a look.

We are between storm systems today, and the result is a nice forecast with sunshine and lots of highs in the 60-63 degree range.

Our next system swings through tomorrow with clouds, showers, and highs in the 50s.

Friday will be dry.

Weekend system...

More questions and answers at this point. My gut feeling at this juncture is that for most in our region, this winds up being a wet scenario as opposed to a white one. But that is definitely not a certainty. Just kind of my feeling at the moment.

I do think there are still a lot of swings left in the modeling over the next couple of days, so we will see.

With the 0z run, the GFS looks way off....too much emphasis placed on the northern stream, result is the low pressure getting drawn way north. The 6z run looks a little better.

The last couple of European model runs look fairly reasonable with a track from the northern Gulf to near the Carolina coast.

If you are wanting snow, what you need to happen is a phase to occur with the system far enough south to allow the phasing to pull southward the necessary cold air aloft. At the moment, the only model really showing at least that possibility is the Canadian. It is there on the Euro too, but the track is a bit too far north for much in the way of NC snow.

A lot of things must go right for snow fans to be happy this time around. The lack of cold air being in place ahead of this system is the biggest problem.

Let's give this another 36 hours or so of model runs to get a better handle on how this will play out. I am not ready to write off the snow scenario, but at lot of dominoes much fall correctly.


Weekend thoughts...

>> Tuesday, February 14, 2012

A few quick thoughts on the 12z model data....a lot of this will be shop talk.....keep that in mind. See the bottom for the bottom line.

12z Euro looked oh so close to a bombing phase around 108, but the phase was not terribly strong I think primarily due the orientation of the Great Lakes disturbance.

12z GFS still looks off to me, like the 6z. The entire orientation of the flow pattern at 500mb is different than most other modeling. It might score the coup though...who knows.

12z Canadian is nice for a chunk of NC. Pretty nice phasing, and because of that, a nice pulling sothward of the colder air aloft.

12z UKMET is weaker and farther south.

Here is what to take from this IMO. I see no trend in the modeling. What I see is each time a model is run, you get its latest interpretation of how a very chaotic 500mb pattern will look this weekend. There is no trend north or south....there is just varying positions and strengths of features.

For the upper Southeast to see a nice winter storm, we want some good phasing. Each model has taken turns showing this from time to time. That is needed to pull the colder air necessary for snow southward, and also get the precip rates heavy enough to overcome some marginal low level temps in some places.

Players remain on the field, and I am no more encouraged or discouraged than I was at this point yesterday. We are just going to have continue to get a handle on how each of the features involved unfolds over the next couple of days.


Lots to discuss....

Here's today's video.....give it a look.

First of all, our system today is behaving as expected with a weakening system interacting with dry air in our region. Some areas will see some snow flakes or sleet pellets this morning, and over in the mountains and parts of the foothills, it could turn the ground white in some spots. However, this is really a novelty event more than anything else, and this afternoon will just feature some light rain at times.

Tomorrow will be fantastic with sunshine and highs in the lower 60s for many.

Another system then moves through Thursday with rain and a few storms possible across parts of the region.

Weekend system...

I encourage you to watch today's video, docked above. Tons of graphics to go along with this discussion.

Lots of talk about our potential weekend storm system. The quick model rundown...

0z Euro came north a bit the track. At face value, it's a rain producer for most folks outside the mountains and maybe some of the foothills, but could end as some snow elsewhere.

0z Canadian and 0z GFS had a nice track for some snow in parts of the foothills, mountains, and parts of the piedmont.

0z UKMET appears to spread some snow through the upper Southeast as well.

6z GFS has come in much slower and really, quite different aloft with the disturbance as it moves into the Southeast and it really minors it out once again. I would throw it out for the time being.

Couple of things to watch.....the quicker the system moves in, the stronger it could be due to it keeping more spacing between it and the next trough diving in out west.

That trough out west, combined with a low over southeast Canada, will keep the low from heading too far north. In fact, I think the 0z European model today is about as far north as this system can make it.

Way too soon for any specifics, but the players remain on the field for somebody in the region to see some wintry precip. I just can't tell you who yet.


Midday thoughts for this weekend....

>> Monday, February 13, 2012

The 12z GFS crushed our potential system. It keeps the southern energy too strong to pop a strong system for the Southeast. See below.
The 12z European model, on the other hand, shows a very nice track for snow in the upper Southeast...including western NC. The 12z European is a little stronger with the phasing than was the 0z, so even though the track of the actual surface low is a touch farther north, the result is still a nice solution for possible western Carolinas snow.
Tons could go wrong, so please, snow fans, don't get excited at this point. The pieces of energy both responsible for the actual system, and responsible for the track the system takes, are still out to sea in the Pacific.
One little thing....I know some will rightly be worried about a northwest trend. Assuming the upper air low near the Canadian maritimes is modeled correctly, this would limit how far north the system can go. But again, that's a big assumption right now.


Active pattern this week...

Whew. What a cold weekend! And it was indeed a decent snow event for the mountains.

As we head into the new work week, there is a lot to talk about. See the video for the graphics to go along with this discussion. Three system to discuss....let's take them one at a time....

System 1:

This one is bringing some snow as far south today as the Tennessee Valley and northeast Texas. As the precip moves into our region, a combination of the upper level disturbance weakening and the very dry air in place will chew up a lot of the precip. However, there could be enough snow flakes or sleet pellets to whiten the ground in some spots of northeast Georgia, the western tip of SC, the western mountains of NC, and southeastern TN.

For the foothills, piedmont, and upstate, there is the chance that a few snow flakes and/ or sleet pellets will work their way through tomorrow morning. However, I just don't think there will be enough precip to amount to anything significant. Some lingering areas of light rain or rain showers will then be possible later tomorrow.

System 2:

This one will be a rain-producer, and it will swing through mainly Thursday.

System 3:

Interesting. With the 0z runs, the Canadian and European model were quite similar with having a surface low near JAX Saturday evening. The 0z GFS was suppressed well south.

However, the 6z GFS has come around and is not advertising a low pressure track very similar to the 0z Canadian and European.

This one will be interesting to watch. I don't like that there isn't really any overly cold air around, but there is enough there that if this takes just the right track, it could produce some wintry precip somewhere in the region.

However, if the upper level energy dampens out (like is happening with system 1), we wind up with little precip. (This is less likely with system 3 due to there not being another disturbance digging behind it though.) Also, if the system amps up too much, warm air floods into much of the region bringing only rain.

Now is not the time for any excitement at all. Threading of the needle will have to take place. But for snow fans, at least there is something there in the 5-6 day range.


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