January 2: Cold, More Cold, and Snow?

Welcome to the WNCN weather blog!  We’ll be using this space to give you even more in-depth North Carolina weather coverage, in addition to what you already see on-air and online.  Basically, this is a place for us to get REALLY nerdy about the science of weather…so it’s fitting that our first post on this blog coincides with a complicated forecast – bitterly cold temperatures for this first week of 2018, and a chance of wintry precipitation as well.

We’ll start with the less-complex aspect of the forecast, which is the absurdly cold weather that has settled in over the eastern two-thirds of the country.  In fact, the coldest weather on Earth (compared to average) is anchored over the eastern United States:

We started off in the single digits and low teens this morning:
We’ll only warm up to the low 30s this afternoon, despite abundant sunshine overhead:
That high of 31 in the Triangle is a full 20 degrees below-average – or, as I like to say, #StupidCold.  (Which, if you’re new to the term, is intended as an emphatic rather than a pejorative – it’s the difference between saying “this cold is stupid” and saying “boy, it’s just stupid cold out there!”)

The forecast gets really complicated tomorrow, so it’s important to emphasize what we know from what we think we know, from what we still don’t know. Ya know?

WHAT WE KNOW: A storm system will work its way up the Atlantic Coast on Wednesday.  The center of circulation will stay well off-shore, but it will be close enough to the coast to throw some moisture inland, into the cold air entrenched over central North Carolina – and that means a chance of snow:

WHAT WE THINK WE KNOW: The air is cold enough both near the ground and farther up in the atmosphere for everything to fall in the form of snow in our neck of the woods – the chance of a rain/snow/ice mix should stay right along the coast.  The timing sets up to bring the first possibility of flakes in around midday Wednesday, with the snow winding down before sunrise Thursday morning.  The European forecast model (one of the most-accurate models, although none of them are perfect) keeps the best chance of snow east and southeast of the Triangle, along and east of I-95:

The heaviest snow will fall along the Coastal Plain – we’re looking at around an inch along I-95, with heavier amounts (4”+) just off to our east, along US-13 from Williamston down to New Bern.  This is the same model’s estimate of total snowfall through early Thursday morning:
Notice how quickly you can go from nothing to a significant amount of snow – this looks like an “all or nothing” snow event, which brings us to…

WHAT WE DON’T KNOW: Here’s the problem – we don’t know exactly where the center of this storm system is going to go.  The system itself is HUGE, hundreds of miles across…so a 20-mile “wiggle” in its path is small compared to the scale of the whole storm, but that would have a dramatic impact on our forecast.  A path slightly farther offshore would take the snow almost entirely out of central North Carolina…and path slightly closer to shore would push the heavier snow directly into our back yard.  The National Weather Service has come up with a good way to visualize this – here’s the Raleigh office’s estimate of a “bust” forecast, or low-end amount:
In other words:
On the other hand, here’s their estimate of a “boom” forecast, or high-end amount:

It’s important to note, the NWS only estimates a 10% chance of either of those extremes happening, but both are within the realm of possibility.  Which is why winter forecasting makes us do this:

The most-likely scenario is what I outlined in the “what we think we know” section – an inch or two of snow along and east of I-95, with the highest amounts in eastern Northampton, Halifax, Edgecombe, Wilson, Wayne and Sampson counties:
That’s my estimate based on the latest data…I’m thinking that the extremely dry air over central North Carolina will eat away at the incoming moisture and help to limit potential accumulations.  The National Weather Service is a little more bullish on the snow, and their “most likely” estimate shows slightly higher amounts:
The NWS has posted a Winter Storm Watch for most of the counties along and east of I-95:

Common sense reactions to the snow and cold will keep you safe 99% of the time…don’t be the person who does this:

If there’s snow on the roads, just slow down, allow extra time to reach your destinations, and allow some extra stopping distance.  Most importantly: THIS IS NOT THE FINAL WORD ON THIS STORM SYSTEM.  We’re constantly evaluating new model data that comes in around-the-clock – I’ll have an update on-air at noon, Wes Hohenstein will have updates throughout our evening newscasts, and we’ll have updates on social media throughout the day.

Once our troublemaker of a storm moves off to the northeast, more cold air will come crashing in for the latter half of the week, and it will stick around into the weekend:
The upper 40s in the forecast early next week will feel like the very breath of spring…but we have to make it through the rest of this week first!

Here’s the other half of the blog…a daily collection of links to nerdy/science reading materials from various places around the interwebs. I’ll start with weather-related content, and transition into other stuff as you go down the list. There may be times that the weather situation is too busy for me to get around to mining the internet for this kind of stuff, but I hope you enjoy it!

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