Rabu, 03 Maret 2010

Wednesday.....



Please see today's video for a detailed wrap-up of the snow event yesterday and last night. On a regional scale, the accumulation forecast I put out worked out pretty well. I had gone with 2-4" for the Triad area, and in most spots, that verified pretty nicely. It looks like the forecast will work out well for much of the RDU area over into northeastern NC and back into the foothills, mountains, and northern Georgia as well.

I mentioned a strip of heavier totals would likely occur, and it did....from the mountains into the foothills and Virginia border counties in the Triad viewing area.

However, the accumulation forecast busted badly from western sections of Charlotte through Gaston and Cleveland counties and down into the Upstate. Plenty of snow fell, but it really struggled to accumulate in this area.

Why? In the Triad, the temp dropped to 33 while the snow was occurring in many spots, and that was good enough to accumulate. For Charlotte back through Gastonia, Shelby, and GSP, the temp dropped to around 34 in many of those places, and accumulations were tough to come by. It did not snow any harder in the Triad than it did in the southern Piedmont. So, the best I can figure is that with the March sun angle, 34 degrees and snow has a tough time accumulating, while 33 degrees and snow accumulated much more easily. At least that is how it worked this time around.

An interesting system, and one I have been tracking with you for well over a week now. Time to put this one to bed and move ahead....

Blustery and cold conditions today with highs in the 40s. Some residual slick spots this morning, especially in the areas that had heavier snow totals.

Each day will get a little milder than the previous one. Tomorrow highs will be in the upper 40s to near 50....by Saturday mid to upper 50s, and maybe some lower 60s by Monday.

We will stay dry through the weekend, and the weekend will be terrific for any outdoor plans you might have.

The next chance of rain arrives Tuesday into Wednesday next week.

Selasa, 02 Maret 2010

Tuesday evening....

For the western Carolinas, the event is winding down. In the Piedmont, the Triad region was the big winner in terms of snow amounts. 5" on the ground in Surry County....at least 2-3" for much of the rest of the viewing area. We will see what transpires in RDU and points eastward tonight.

Much of the Charlotte region and the Upstate got the short end of the stick in terms of accumulations. A dusting to and inch for some, but overall, the accumulations were disappointing in that part of the region. Still some more minor accumulations could occur east and south of I-85 for a little while longer this evening.

It looks like for the Charlotte region, the combination of the snow falling during the day and surface temps only dipping to 34 degrees or so through the day really hurt accumulations. The Triad did ok, and temps hovered around 33 much of the day there. That degree can mean the difference in grassy accumulations and nothing.

As always, I will take a look at the accumulation totals in tomorrow morning's video and blog post and see how everything turned out. I never hide from my forecast....and I will publicly critique it as always.

I want to take a moment and give a big thank you for following the blog and videos. It is humbling to me that you take the time to stop by. Keep on stopping by even though the winter season is winding down. We always have some interesting weather to talk about, if not here then somewhere close by. I will keep the daily posts and video going as always right through the warm weather season.....we will have severe weather, flooding, and the tropics to discuss among other things. So, if you have an interest in the weather, don't be a stranger!

Quick afternoon hit.....

Lots of big, beautiful snowflakes falling around the region this afternoon. Really a nice sight.

The snow is having a really tough time accumulating due to the early March sun angle and temps just above freezing. So, I have a feeling this is really going to cut into the snow accumulations in a lot of places.

So, hopefully, for the folks wanting accumulations, you will get what you want. If nothing else, at least we got to see some beautiful daytime snow.....

Midday update....

Band of moderate to heavy snow looks to set up shop in a wide swath centered near I-85. High rates of snow will really crank up in parts of Georgia up into the Upstate and likely up into parts of the NC Piedmont in time. Modeling has come into fairly good agreement, and we will likely see that band of moderate to heavy snow gradually pivot up through N GA, SC, and the NC Piedmont and shift eastward with time.

Accumulation amounts are going to vary greatly depending on where the heavier embedded bands set up. Would not be surprised to see some 6+" amounts somewhere around the region while others see only minor accumulations. 

The heavier snow bands could very well develop over into eastern parts of NC as well by this evening.

Those that are getting the snow....enjoy!

Difficult forecast....



I can not remember a tougher snow accumulation forecast off-hand. The entire atmosphere across much of the region is sub-freezing until you get down to the surface and just above. Because of that above freezing air near the ground, it will take some heavier rates of precip to get the precip to be snow and not rain, at least initially.

As of now, I am not making any huge changes to my going forecast, but I have changed the orientation of the accumulation areas a bit. For the Triad, Charlotte and into the foothills, I will go with 2-4" with some locally higher amounts, mainly northwest of I-85.

Around RDU, especially just east of there, right up through northeastern NC I have another area of 2-4". From Atlanta to Columbia along I-40 and points north I have 2-4" as well. Most other areas are in the dusting to 2" category.

There will likely be a strip that sees in excess of 4 or even 5 inches, but where that sets up is still very tricky. Other areas that do not get the heavier rates of precip will have a tough time seeing accumulations at all. See the video for details.

It will be cold and breezy tomorrow, and temps remain in the 40s for highs through Friday. Warmer weather rolls in this weekend and early next week.

Senin, 01 Maret 2010

Afternoon thoughts....


Quick thoughts here.....the upper low is departing the NE coastline as expected, and our next system is looking very healthy in eastern Texas. Looking at the upper level features comparing what is actually occurring to the 12z 6 hour forecasts of the NAM and GFS, and frankly both models are doing a pretty decent job. The GFS is handling the current precip to our west better than the NAM.

Almost all modeling has come in wetter with the precip amounts. The NAM keeps the heaviest precip just south of a Charlotte to just south of Raleigh line. The GFS continued the trend I showed on the video this morning with its 12z run of increasing precip totals a bit further.

The reason the GFS is wetter than the NAM is its handling of the upper level features as we head through tomorrow. The NAM weakens the 850mb low for a short time before strengthening it off of the coast, while the GFS strengthens the 850mb low during its trek off to our south.

This will play a huge role in the total precip amounts for the I-85 corridor, especially in NC.

I feel the right idea at this point is to up the snow totals I had put out this morning.

Also, at this point, don't concern yourself with the convection near the Gulf. That is right ahead of the developing main surface low, and that is forecast to be there at this point. If by very early tomorrow morning precip is not blossoming in northern and central Alabama, then that is cause for concern for the forecast.

Many Carolina spots will likely see the precip begin as rain for a while before the rain/snow line establishes itself. Exactly where that sets up initially is tricky, but I would expect it to move eastward as we get toward late tomorrow afternoon and evening.

These are some general ideas.....

Charlotte: 2-5"
Triad: 2-4"
Raleigh: 2-5"
GSP: 3-6"
Atlanta: 3-6"

Now, it is very tricky as near ground temps will likely be a bit above freezing through the event. If the lower amounts of precip on some of the modeling verify, it will drastically cut down on snow accumulation potential. This is the type of event where it will take heavy rates of precipitation to get accumulating snow. So, if the precip remains light, significant accumulations will be difficult.

Like I mentioned this morning, of all of the winter weather threats we have seen this season, this one, in my opinion, is the toughest to forecast for a day before.

Next system rolling our way....



I will say right off of the bat....this is a fairly low-confidence forecast. As I mentioned back on Friday, with as much model agreement as there was, you were simply waiting on complications to arise. And they did over the weekend, and they continue as I type.

Some models are very dry with the precip output from our next system, while others are much wetter, and getting wetter (GFS). For my forecast package this morning, I have leaned in the direction of the wetter models for a couple of reasons. First of all, the seasonal trend has been for systems to over-perform on precip output. Secondly, the system looks very impressive as of now.

Ahead of the system, today will be quiet with increasing clouds and highs in the lower 50s. Tonight will be cloudy with lows close to freezing.

For the Carolinas, precip will arrive very early in the day tomorrow. Initially some rain could be involved, but I think very quickly locations roughly along and north of I-85 transition to primarily snow. As the low pressure strengthens along the coast, the rain/snow line will gradually shift eastward.

In terms of potential accumulations, see my map below. Keep in mind....this is my preliminary outlook....changes could be made as we go forward.

For the Triad, I will go with a general 1-3" snow. Much the same for RDU, although it gets trickier as you head east due slightly warmer surface temps. Eastern NC accumulations will all depend on how strong the low is as it cranks off of the coast.

For the Charlotte region, I will go with a general 1-3" area just north and west of town with 2-4" along and just south of I-85 down through the Upstate and into parts of northern Georgia. Again, see the map below.

Please note that if the drier modeling verifies, this forecast will bust badly. But those are my thoughts as of now. Time will tell.