Winter storm wrap-up

>> Thursday, February 26, 2015

The good, the bad, and the ugly of the winter storm forecast:

If you watched my video yesterday morning, I went into how the forecast was going to be very tricky for eastern sides of the Charlotte metro up into southern parts of the RDU metro. This was due to a pronounced layer of warm air aloft causing mixing of precip types.

Well, that warm nose aloft was even more pronounced and more north than expected, and that really sullied my snow amount forecast around the Charlotte area and Upstate. Now for the Triad area, the forecast panned out very nicely with many folks in many counties reporting 6-8". So that area did fine. The problem was southern NC and Upstate SC.

Remember those RPM (Futurecast) runs that looked somewhat absurd with the rain/ snow line so far north? Yeah, it was pretty darn accurate in retrospect. It won the model day. For instance, looking at sounding data yesterday, the GFS never got Charlotte out of a snow sounding. The NAM, while much more pronounced with the warm nose, kept CLT at a snow sounding deep into the night, and even then, it was close to isothermal snow soundings. There was nothing on those models that indicated sleet and rain taking over so early in the evening. Some of the high-res short-term models were indicting warming aloft, but it was difficult to take them too seriously while there were spitting out 20" snow products.

The first warning shots to me were fired when a buddy of mine near Anderson, SC let me know he was in a sleet/ snow/ rain war zone early in the evening. I knew we were in trouble then.

So what exactly went wrong with that aspect of the forecast? Again, I thought the area just east of CLT and down into northern SC was going to be trouble. But I thought most of CLT, and certainly areas north and west of Charlotte, would stay primarily snow. They did not, until you went north of the whole metro. The warm nose aloft won out, and a whole lot of the precipitation fell as sleet and rain, especially CLT and points south and east.

The problem had little to nothing to do with ground temps or surface temps. Look at how quickly snow stacked up while precip remained all snow, and look how quickly snow accumulated Tuesday morning with ground temps warmer than last night.

There was always going to be a tight gradient with this just set up further north than expected. Lesson learned. Never, ever, underestimate the warm nose.


Winter Storm Headed In Tonight

>> Wednesday, February 25, 2015

Please take time to watch today's video... it will answer a lot of your questions.

A challenging winter storm forecast this morning.... an area of low pressure will take a pretty classic Carolina snowstorm track today and tonight....near the FL Panhandle this evening to near the Carolina coast tomorrow morning. This will spread a shield of snow from NE Texas this morning, across north MS, north AL, TN, and then into parts of the Carolinas this evening and tonight.

As is typically the case in this type of event, there will be a sharp rain-snow line, and areas near and just north of the rain/snow line will likely have the heaviest rates of snow and highest snow totals. There are indications on some of the modeling of slightly warmer air aloft working in from eastern sections of the Charlotte viewing area up toward southern parts of the Triangle viewing area, and I show that in today's video.

There are also indications of mesoscale banding with some heavy rates of snow possible just north of that rain/snow line, so a very tight gradient of snow totals looks likely. If this small-scale banding set up, some areas will likely exceed the snow totals on the map below. This is most likely in the pink shaded area.

Here are my accumulation thoughts as of now, subject to adjustment.

Regionally.... very tricky for Birmingham, Atlanta, Columbia, and Sandhills areas especially.


Accumulating snow ahead?

>> Monday, February 23, 2015

I encourage you to watch today's video for all of the graphics that go along with this morning's discussion:

A chilly and active weather pattern is in place this week across the Southeast. One pretty weak disturbance will move in tomorrow morning and bring the chance of some flurries or a little light snow to some areas late tonight into tomorrow morning. However, this system looks rather deprived of significant precipitation.

A much more significant system will then roll into the region by Wednesday night. While some computer modeling has been indicating a suppressed solution where more of the precipitation remains south of a large portion of NC, I do not feel this is correct. At this point, I favor a solution of a surface low tracking from near the FL Panhandle to just off the Carolina coast Wednesday night into Thursday morning.

Assuming that idea is correct, a strip of accumulating snow would occur from northern MS and AL up through north GA, Upstate and parts of northern SC and then much of NC.

It all hinges in this:

This is a snapshot from the 0z European model. If that energy of the Deep South remains more tightly bundled, like the European, UKMET, NAVGEM, NAM, and many Euro and GFS ensemble members show, the idea I have laid out above has merit.

What can go wrong? First of all, there is only so far NW this can trend this time around due to the big low in SE Canada and the Northeast, so some additional NW ticks are possible, but I don't think this winds up a big rainstorm for western and central NC. Areas in northern SC could get trickier.

If they energy is more strung out, then a weaker, further south solution is possible. That is definitely a possibility, but I don't think it's a likelihood at this point.

In fact, history tells me that if anything, we might see that upper level energy trend stronger as the models begin to 'see' it better. But we will see.

Things often change a lot with these systems, but that's the way I see it as of now.


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