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Not that one should waffle back and forth with each model run, but as you get closer to an event, presumably model guidance should improve.  After several cycles of trending drier, the 18Z models have come back around wetter, owing to more precip from the low deepening as it exits the coast.  Under the the latest runs, it would be snow at the onset, to sleet, to a freezing rain glaze on top.  Could be, but I’m not ready to fall for this tease yet.  For now, we’ll just wait for more data to come in and watch the system as it begins to organize tonight over the TN Valley.  Tonight’s model runs should be more reliable with fresh data included in their initializations.  We’ll see if we have reversed the trend back a little wetter or not.  Any way you slice this, it will not be a heavy event.  The question is…will this be just a nuisance or create minor travel headaches.  More tonight.

Moisture really looks starved for tomorrow.  So, for the second dance in a row, it looks like the guest of honor won’t show.  For a good portion of central NC, I think this will play out as a couple of snow and sleet showers that will in some places accumulate enough for a dusting to a half inch, and other places not even that.  Actually the locations that will stand the best chance of getting and inch or so look to be from Rocky Mount northeastward.  It’s ashamed to waste all this perfectly great cold air…alas, it is NC.

Next week we thaw out with the possibility of highs flirting with 70, before the cold returns.  And it could be another significant cold spell thru the first half of Feb.  Perhaps more chances for the elusive snow then.

As I, and everyone else it seems, have said, the limiting factor with this next round of winter is moisture.  The range of possibilities for the Triangle are from a couple of spotty snow or sleet showers that dust the surface, to a band or two of heavier precip that lay down a couple of inches.  Right now, at best I could wishcast 2-3 inches in Raleigh.  For those who love to see white stuff on the ground, the good news is that antecedent conditions are so cold that pretty much whatever falls should stay there, making for easy accumulation.  The question will be…how much moisture is available to overcome the very dry air in place.  I can see the potential for how this could swing for enhanced QPF, but really that’s just wishful thinking at this point.  My first call for Raleigh is 1″ of frozen ‘stuff’…snow and sleet…maybe some frozen drizzle on the back end.  Remember though that this event will begin after lunch on Friday and continue thru the evening to impact rush hour, so it may cause disproportionate headache to the depth of accumulation.

More tomorrow.

Last dance, I asked ‘Cold’ if she’d come, because I knew I was bringing the wet.  This go round, I’m asking ‘Wet’ to the dance, because I’m bringing the cold.

Last week, we had a lot of moisture with only marginal cold.  This time it looks like we’ll have plenty of cold air (at the surface, at least), but an abundance of moisture is the question with Friday’s system.  In fact, the extent to which the air mass in place will be cold and quite dry makes me fear this will be one of those events that we agonize over available moisture…how much it takes to saturate the dry in situ air vs. what’s left over for ice accumulation.   You know the drill…we see radar echoes roll in from the west, patiently waiting for them to reach the ground, only to end up with a spotty sleet shower or two.

There’s lots of time to figure this out, so we’ll patiently follow the trends.  To clarify timeframe…probably beginning Friday, early afternoon.

So, here’s me hoping that ‘Wet’ shows up this time.  But I’m a little dejected lately, with ‘Cold’ just flirting last time and what about that preseason-advertised Wolfpack?  Yes, they’ll dance, but will they be special?

…and it looks like we’ll have one on Friday.  Whether or not the wintry materializes, the meteorologists will be sweating this one, no doubt.

It’s funny that we rely on models so much for our forecasts, but in this case the meteorologists have really been observing patterns that may turn out to have outwitted the long-range numerical gibberish.  Friday looks to be a classic cold air damming (CAD) event for NC.  The US models, in particular, have not respected this solution, but the European is trending toward a low track farther south, around the base of the cold pool.  This solution would create an icy mess across the NC Piedmont with more snow farther west in the foothills and mountains.  It’s way too early to say any more than, we have the potential for an winter weather event.  So, I’ll leave it at that, and go see if I can find a date for this dance!

A couple of quick points:

1)  The coldest air since last winter is on tap for midweek.  Highs Tues and Wed will not make it out of the 30s, despite lots of sun and some harmless cirrus.  Lows Tues night should reach the upper teens, especially outside the city.

2)  It should begin to moderate late week as the next front swings thru bringing a cold rain, but secondary low development along the front could make for another wintry mess and forecast headache late Friday into Sat.

At the risk of being Captain Obvious, the colder air has arrived and the changeover is nearly complete thru most of the Triangle.  Precipitation rates will now dictate local accumulations.  We should see a lull in the precip intensity in the next hour, before the bands in association with the upper-level vortex, currently over upstate SC, rotate thru here after midnight.  In the lighter bands in the interim, you could very well see a rain/sleet mix, until the final snow.

So, enjoy the snow.  The bursts should make for some real purty!

And so, as the dance comes to a close, she finally made it.  We sway as Madonna plays loud and a teacher yells… “daylight, kids!  let me see daylight!”

Enjoy this one…Crazy for You

Well, here I am…all gussied up and smelling nice.  The music is thumping and the gym is dotted with groups of awkward adolescents swaying in clumsy cadence.  Now all she has to do is show up.  She…being the cold air, of course.

The thinking behind the forecast is basically unchanged from yesterday.  The models have been quite consistent and in agreement on the system’s evolution.  Yet, even as it would seem that the snow is on, the same nagging questions about the arrival of ‘the cold’ linger.  That, combined with warm ground temps, makes me worry.  Finally, the 18Z models dry us out a little quicker on the back end, which is also troubling.

It will definitely snow.  But, the accumulation of snow is predicated solely on the fact that it’s going to snow so hard to overcome a lot of warmth in the boundary layer.  It’s one of those situations where everyone will get some grassy accumulation, but maybe not much else unless the heavy snow is realized.  Under those heavy snow bands, the snow will accumulate quickly, maybe as much as 2+ inches per hour…and these are the locations that could see 5″.

As we get into early evening and we see what the radar signature looks like, we should be able to nowcast more accurately.  For now, i’m cautiously optimistic to stand by what I outlined last night, which is pretty consistent with the NWS and media.  But my tendency would be to skew to the low side rather than the high side until we see evidence that the cold is making real progress.  In Raleigh, I would think we won’t changeover until 9.

So until then, I’ll be hanging out at the dance, just waiting and listening to sappy 80s power ballads.  Click the play button to enjoy this one…

Alright, I give in.  I’ll be waiting at the dance…again.  I’m ready to put out my first guess for accumulations.

Looks like the dynamics of this storm might be so impressive as to generate thunder snow.  The last thunder snow we had in the Triangle was during the most impressive snow we’ve ever seen, back in Jan (24th) of 2000 with 20″+.  So, tomorrow night when you’re out watching it snow, look for cloud to cloud lightning, even if it’s difficult to hear the thunder.  And these impressive dynamics could be the key to realizing impressive snow accumulations in spite of warm ground temps from our recent Indian Summer.  I’m thinking that after we see the changeover tomorrow evening, we’ll see a general swath of 1-3″ in the Triangle and on either side of the line I prescribed in my previous post…obviously with the dustings to 1″ on southern and easterly edges and the higher totals to the north and west.  But, the wildcard will be how the mesoscale bands set up.  The bands of convective snow could add another 1-2″ on top of these more general totals.  The sweet spot, though, for those near the Triangle looks to be just over the Virginia border where, depending on how those bands set up, should range 5-10″.

I’ll fine tune this tomorrow.

I feel like I’m in middle school…I’ve been talking with a cute girl.  She’s very flirty.  I invite her to the dance.  We agree to meet there because she’s going to come late.  I wait.  The clock ticks on.  There are only a few more minutes before the dance is over.  She’s still not here.  The last song begins to play.  Where is she?  You see where this is going.

Tomorrow’s situation is a classic setup for heartbreak of the NC snow lover.  Lots of moisture and lots of rain on the front end of the storm.  Plenty of cold air advection and dynamic cooling aloft to suggest a changeover to snow on the back end.  But therein lies the rub.  Time after time it seems so clear, only to have hopes dashed as the cold air rushes in behind the storm and erodes the moisture field.  This girl has stood me up at the dance too many times for me to easily buy it this go round.  That’s why from the get-go on this one, I’ve been saying that I’m skeptical.

The past several model runs have come into convincing consensus as to the evolution of the approaching storm.  As I mentioned, there will be good soaking rains during the day Thursday, transitioning thru a rain/snow mix to all snow overnight into early Friday morning.  Of course, the question is…when is the change in relation to the end of the precipitation?  (Will she show up before the dance is over?)

At this point I’m ready to say that it will snow north and west of a line from Rocky Mount to the Triangle to the just north of Charlotte.  And probably, that line will end up being the line for accumulating snow.  North and west of that line there will be significant snows…especially, toward Greensboro and Roxboro into southern Virginia and of course, the mountains.  More specifics later.

We’ll see how the dance goes this time around.  Maybe she’ll show up early for bigger snows, or maybe it’ll be the same scenario where we’re left waiting for her to show as the music fades…

For those who grew up in the 80s, click on the play button, close your eyes and picture the middle school dance…