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Now, Now Kids… Let’s Play ICE

We are now entering the “short term modeling window”. To this point, we’ve been using large-scale models for general macroscale storm guidance. There is now general consensus on the evolution of the storm such that, the track of the surface low (and coastal front with its warm push intrusion) probably won’t differ by more than 20 to 50 miles. Those 20-50 miles will be crucial for those on the eastern edge battle front, which will be near Wake County.

Let’s back up to clarify… barring any crazy last minute monkey-wrenches, the outline from last night holds. In Raleigh, we should see snow begin 4-6am Sunday morning. This will be short-lived. Expect the snow to change to sleet quickly. I expect the sleet to be short-lived as well.

The snow and sleet should lay down coverage from a light coating to an inch or so. Then, the freezing rain begins. The question becomes how long does the cold air damming remain in place against the intrusion of the warm air behind the coastal front moving from SE to NW. Here’s where the short term modeling comes into play…

Up to this point, we’ve been using large scale, coarse model grid points. Now, in the short term, the grid spacing gets much tighter, and more reliable for resolving local-scale problems like… “How far west will the surface freezing line make it?” This is key to Raleigh. The longer we stay below freezing, the more crippling accrual of ice we get.

No need to guess tonight, I’ll provide more precise ideas on what that looks like in a post tomorrow. Tonight, the key takeaway is that Sunday looks to be a treacherous travel situation. Make alternate plans.

Bonus… some of the short term models suggest that we may see a period of snow Sat afternoon. Should be inconsequential, but pretty!

Ice, Ice Baby?

Lots of time before this event… Tonight, the best guess for Raleigh is for a little bit of snow — to significant sleet — to significant iceand then rain at the end of the event.

Happy New Year!

I could/should wax poetic over the couple of different scenarios on the table as to our impending winter weather event. However, the main message to convey is that a significant winter storm is likely to impact Raleigh west thru the mountains, beginning early Sunday morning (earlier from the west to east).

As disappointing as it might be for clarity, there’s no need to hypothesize as to scenarios until we get closer in the Fri PM/Sat AM timeframe. Honestly, all solutions are on the table at this point, and we’ll probably waffle back and forth over the next couple days.

Tonight’s read indicates an impactful snow to sleet to freezing rain to rain event in Raleigh. Then, along a gradient as you go west to Greensboro you’ll see an all frozen… more snow, more sleet and freezing rain.

Happy snow-dreaming!

Things Are Looking Up…

…as in, I’m looking to up expected snow totals a bit… albeit with the risk of a Charlie Brown, Lucy, football reenactment!

A consensus is forming in the numerical guidance with regard to tonight’s snow event. QPFs have trended higher, which will lead to greater cooling of the column, which will lead to higher snow totals across the northern half of NC.

We should see precipitation break out in the Triangle in the form of rain around 9pm. Then, we’ll see that typical cold, NC winter rain thru midnight. Between midnight and 1am we should see the changeover to all snow. Precipitation rates look to be moderate, so I would expect some picturesque moderate to even heavy snow. There will be a window of just 4-5 hours for the snow, and most of it should be wrapped up by dawn. If you want to see it, set those middle of the night alarms for 3am!

Expected heaviest accumulations north of a line from Greensboro to Raleigh to Wilson. Totals will range 2-4″ with perhaps some 5-6″ totals toward the Virginia border. A good target for Raleigh is around 3″. Bust potential to the downside will be just a dusting. Bust potential to the high side would be 5″.

Ground temps and particularly road temps are fairly warm, so this accumulation will be primarily in the grass, especially early. Although with the anticipated heavier snow rates, the roads could eventual succumb to the snow. However, once the snow stops and the sun comes up, any problems will quickly dissipate.

I’m still eyeing the next system for Sunday. However, we may turn out to be on the warm side of that, but it’s something to continue to monitor. And especially interests north and west should keep tabs on the latest.

Winter Weather to Return to NC

A quick heads up on the system for overnight Wed into early Thurs AM that we’ve been eyeing for over a week now. Just as hope was fading, the numerical modeling has strongly trended to a more favorable alignment of the surface low and upper-level energy over the past day or so. And while this won’t be the ‘big one’ or anything like that. It does appear more likely that rain will changeover to snow late Wed night with the potential for light accumulations especially on grassy areas.

There is the potential for some moderate banding in this scenario which could yield higher lollipop totals scattered among a more general swath of 1/2″ to 2″ snows. There’s still plenty of time to follow the latest trends tonight and thru the day tomorrow.

Perhaps of more interest though is a second potential winter event late Sat into Sunday that advertises as what could be a more prolonged bout with a mixed bag of all p-types for a winter mess of significant accumulations of ice, sleet and snow across a good chance of NC.

Minor Event for the Triangle

Happy 2021! It’s good to have a winter weather event to talk about!

For Raleigh, it looks like the initial precip begins between 3 and 5am. Probably initial as rain, with a brief changeover to a sleet, rain, wet snow mix, which then changes over to all rain as we approach rush hour. Any wintry p-type in this first round should be of no consequence.

During the day, the rain will be spotty and light with temperatures hovering in the mid-30s. (a beautiful day!). Then tomorrow evening in the 7-9pm range snow showers will begin to break out in response to the cold upper-level low rotating thru. We’ll have a 3 to max 4 hour window til just after midnight of snow showers, some of which have the potential to be moderate. This is will be the time when Raleigh sees the potential for accumulating snow, in particular on grassy areas. Most likely, accumulations will be 1/2″ to 1.5″. Bust low would be snow in the air, none on the ground. Bust high would be 2-3″. Snow totals will not be uniform. They will be banded more like what you see with thunderstorm distributions in the summer.

Enjoy!

I Was Wrong

Couple of things…

1) the antecedent ground temperatures really held their own — while it was snowing really hard, it worked. but now the precip rates are winding down earlier than anticipated, which brings me to…

2) the axis of enhanced moisture never extended as far north as advertised— that means that the NE corner of the state that was expected to be the winner will end up underfed. In Wake county, while the snow coming down now is lovely, there will be little to no additional accumulation.

Still the temps will drop well below freezing tonight and all that slush on the roads will be treacherous tomorrow. The question then becomes how much melting and evaporation do we get tomorrow…should be a lot… to prevent more back ice on Sat AM when temps will plummet to the lower 20s.

Then… guess what… I’m watching the potential for another winter event next weekend! Fun times. Enjoy!

Snow…Pack!

Looks like the Pack victory was a good call! Now onto the snow to complete the “snow-pack”!

Precip should begin arriving not too long after lunch. With dry air rushing in on the back of a stiff NE breeze, any rain and sleet should quickly change over to snow. As we approach rush hour, the intensity of the snow should pick up and we should be in for a beautiful snow thru the evening.

Let’s say 3-5″ for Wake county. Again, the real winners look to be east where it should be 8+. Back towards Greensboro and Charlotte look for more like 1-2″

Looking ahead, Saturday morning lows will be near 20. That hard freeze will make for bad traveling on whatever is on the roads.

Short Term Models Looking Good

I thought I’d push a quick post 1) as another test that my website issues are resolved, and 2) because I won’t get to update until after the Wolfpack beats Duke in the late 9pm game tonight!

The models continue to come in, in support of a significant winter storm in central and especially, eastern NC. The short term ensembles are impressive as well.

I still like the axis of heaviest snow to line up from Raleigh and extending northeastward toward Norfolk. I feel more comfortable with the idea of something closer to 4 or 5″ in Raleigh with higher totals in that Rocky Mount to Edenton zone nearing 8″.

More tonight, after the Wolfpack’s victory. 🐺

Euro Rights the Ship?

I’m sorry to not have posted until now. There were technical problems with the website. (perhaps I was hacked by the Europeans so I couldn’t poo poo their model 😉

While certainly it is too early to declare an American model victory, what can be said is that the deterministic Euro and its ensembles have steadily ticked up from 0 to 3+” for central and eastern NC over the last 4 runs. It should be reiterated that the Euro skill scores are statistically superior over all global models, but as they say… you can’t win ’em all. That appears to be what’s going on here.

Comparison of Euro snow maps from yesterday 12Z to early this AM at 6Z

Snow looks likely for a good swath of NC tomorrow thru early Friday AM. The NAM, while maybe overdone, has displayed remarkable run-to-run consistency. It is insistent on strong frontogenetic forcing which would drive heavy precip rates. Those heavy precip rates will be key in overcoming warm antecedent ground temps.

A concern with all this strong forcing is how far north the warm nose will extend. The warm nose (elevated layer of temps > 0° C) will turn snow over to sleet and reduce totals in those areas. Right now it looks like the warm nose will make it no farther north than central to southern Wake county.

I’d like to digest the complete set of 12Z model runs before passing judgment. And, of course there’s a problem with the GFS coming in this cycle. At this point it’s about an hour late.

The skinny… Precip starts late tomorrow AM as rain or rain/snow mix. Changes to snow for a good chunk of NC. Mixes with and changes to sleet in the south. Storm totals highest from Raleigh north and east. Raleigh is probably 2-4″, up to 6-8″ toward Rocky Mount and to Edenton.


Play It Again, Sam

Raleigh has escaped the storm with the best possible outcome…a beautiful 4-7″ snow and temps hovering just above freezing to avoid any damaging ice build up.

But wait, there’s more…

It looks like there will be another round of snow and sleet early tomorrow AM as another shortwave rounds the trough.  The latest trends in the modeling indicate there could be another burst of heavy precip for at least a couple hours.  Surface temps will again be hovering close to freezing, but the precipitation rates should be high enough to achieve more accumulation.  This doesn’t look to be the case for everyone in NC, but under this band should be a thumping of 1-2″ …possibly isolated cases of 3 or 4″.   Right now the Triangle looks to be included in this next round.  And this would be just in time for tomorrow’s morning commute.  More winter fun!

Tomorrow evening clearing will following and temps will drop to the mid 20’s for lows.  Refreezing will be a major issue on Tuesday morning.