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It’s been a while since there’s been much to talk about in terms of wintry weather for Raleigh (aside from a quick blast of boo chilly air last week).  So today, in between monsoonal downpours, we are watching the potential for a significant icing event overnight Tuesday thru lunch on Wednesday.

A fresh supply of cold air will begin arriving in NC as the rain exits later this evening.  So, the extent of low level cold air supply will not be in question.  The uncertainty will be in how much precip will fall in the Triangle, owing to a weak surface low riding up the coast.  The axis of heaviest precip will certainly lie to the east of Raleigh.  The extent to which it bulges back westward will be the question.

Models differ on this, ranging from just some drizzle and a hundredth or two of liquid equiv, to up to a 1/4″ of liquid equiv (QPF).  At this point, I would expect around a 1/10″ of ice accumulation, which will be enough to make for bad driving and a few problems, but not result in widespread power outages and/or bring lots of tree limbs down.  We’ll watch to see how the numerical guidance trends with QPF over the next day to get a better handle on if this will be just a nuisance event or something to make alternate plans for.

As to timing…It appears that we will be lucky that the freezing rain should begin late Tues evening (10pm to midnight) and continue overnight into Wed AM.  This should help with fewer travel problems, and let people evaluate the conditions Wed AM before venturing out.

More updates later.  But if you would like more frequent updates, follow me on twitter at:  trextrex14

Ok, no Thanksgiving blizzard for Raleigh, but maybe there will be some snow in NC on Wednesday with the potential for some hefty snow in the Mid-Atlantic and NorthEast to make for a ‘gizzard blizzard’!

There is mounting evidence to suggest the possibility of a wet snow event in central NC late Tuesday and Wednesday.  The cold will be marginal, but heavier precip rates might be able to overcome warm boundary layer temps.  Alternatively, we could have everyone’s favorite…a cold 35° rain.

Still a lot of uncertainty and variety of solutions to study.  At this point the euro ensembles give it a 1 in 3 shot of measurable snow.  The operational GFS has been bullish for the past couple runs, but it’s interesting to see that the beta version of the new GFS upgrade which has been performing well, isn’t biting…yet.

I figured I should turn the snow showers on for the webpage…

Happy start to winter!  Don’t worry what the calendar says.  Next week a monster arctic high (especially for Nov) invades the US with A LOT of cold air.  Cold temps arrive here at the end of the week, and then could there be an over-running situation late Fri or Sat?!  something frozen?!

It’s a long way off and lots to debate over the next week, but what looks like a great bet is the cold!

Oh, and watch out for one more round of mod to heavy showers with maybe a clap of thunder before the night is out.

…but rain is the more likely p-type.

With boundary layer temperatures several degrees above freezing, it will take heavier bouts of precip to drive any mix with or change to snow.  And while the axis of heavier moisture looks confined east of I-95, it wouldn’t take much to back it into Raleigh as the coastal low develops off Hatteras.

So, I’ll stick with cold rain, sometimes mixed with snow, and probably even a shower where it’s all snow for a while…but not enough to accumulate on any roads…lucky to accumulate on elevated surfaces north of the Triangle.  All this with the caveat to that everything evolves with the deep moisture to the east.  We’ll monitor and see.

That’s for us.  But more exciting will be to watch this storm bomb out up the coast with hurricane forces winds on Cape Cod.

As to the question of “To Sea or Not to Sea?”… I think we still have to wait and “see”.  No doubt, the majority of the modeling indicates that the eventual explosive cyclogenesis should take place offshore far enough preclude an I-95 corridor blizzard.  However, there are some things that just don’t seem right to me.

Anytime we have coastal cyclogenesis the uncertainty level is heightened.  In this case, multiple different shortwaves will interact and incite two surface lows off the East Coast.  The various models differ on where each of these lows form and how they track north.  What is unifying in the solutions is that one low cannibalizes the other as it bombs out heading for Nova Scotia.  In many of the simulations the more south and east low predominates and much of the energy is pulled east.  In the latest, Euro there’s even a Fujiwhara-like tango of the two low centers…It seems weird to me that the more western low would lose out to the eastern low, especially since the western low should be fed by the warm Gulf Stream.  See the current SST (sea surface temperature) anomalies…

By now you’re probably bored and want me to cut to the chase as to what this means for NC, so I’ll oblige… I don’t know.  Just picking.  Kind of…

For clarification of time…this will be Tues AM.  Following the party line would be to say that development of a coastal low will confine the deepest moisture and precip totals east of Raleigh.  And without sufficient precip, it will be tough to cool the boundary layer to near freezing.  That means that there should be a cold rain mixed with snow, especially in relatively heavier showers of precip.  But we’re only talking .1″ of liquid equivalent, so not much of anything.  Heavier precip amounts will be found farther east to the coast.  In the northeast part of NC into eastern VA is where there could be more snow mixed in.

All this is based on the low developing sufficiently offshore, a westward jaunt of 100 miles would mean heavier precip rates and more heavy wet snow into Raleigh.  Perhaps I’m being foolish about this, but I want to see more agreement in the modeling before I pronounce this scenario off the table.

If you’re traveling north this week.  Boston and Cape Cod look to get clocked.  Again I want to see how this dueling low thing plays out and which dominates, but under the western-dominant low idea we would see lots of snow back into Long Island and double digit totals even into NYC with several inches back to Philly and tapering back south and west.

Lots of time yet to fret!

…that is the question.

Like I said yesterday, we’re in that mid-game time when a track out to sea comes into play.  Certainly the 12Z runs of pretty much all of the models have shifted east.  The other trend this go round has been to rapidly deepen the low (bomb it out) as it races north, which is also something we were looking for.

There is good consensus on the potential for a very powerful Nor’easter with pressures nearing 960mb (that’s low…’Superstorm Sandy made landfall in Jersey with a pressure of 946mb).  Of course, this will happen when it bombs out off the New England coast.  The question is, what does the track look like.  And we won’t really be able to say with any confidence until the energy (that thousands of miles away and will eventually grow to be the storm) is sampled by upper air observations on Saturday.  Once those observations are integrated into the models, then things will become more clear.

For you snow lovers, don’t take this as the kiss of death, because it certainly is not. And, in fact, this AM’s GFS still depicted several inches of snow for central and eastern NC.

Bottom line is that tonight’s models won’t interest me as much as those beginning tomorrow AM, but especially into Sunday.

There is remarkable agreement among the various models as to a significant coastal winter storm next Tues and Wed that will affect the Carolinas thru the Mid-Atlantic and perhaps southern New England.  But it’s about that time in the mid-range where many times the models “lose” the storm altogether or usher it out to sea for a couple of model cycles.  It’ll be interesting to see if that happens.

But at this point, both the operational and control runs, as well as most of the ensemble members, show a late-season winter storm that looks to add enough snow to break all-time snow totals for the month of March in the Mid-Atlantic.

Standard NC winter weather caveats apply…much can change in several days and a storm like this is definitely climatologically unfavorable.  But…all other signs are pointing to just the right ingredients coming together.

Finally, as I said in the last post, the last time Raleigh had a major snow this late in the season was 7.3″ in 1983.  As I recall, it was a time of Cinderellas, if you know what I mean.  And maybe, just maybe…tonight another red team hops a ride on the pumpkin coach!

What’s today?  Is it March 15th? Oh no, it’s not…it must be the Ice of March.  r r r

I mentioned yesterday that the cold will return early next week…and now I’d like to mention that next Tuesday we’re in the running for another late season snowstorm.  Ironically, it was on March 24th of 1983 that RDU recorded it’s biggest snowfall so late in the season.  And there are several instances of late season snows clustered in the March 24-27th range over the years (with 1983 being the biggest at 7.3″).  And if you’re curious, the latest measurable snow of the season at RDU was April 18th with a little under 2″.

Of course, nothing is set in stone for early next week.  At this point,  the cold looks to return and there is ensemble modeling support for costal cyclogenesis.  The details will come into focus in the coming days.