What In Tarnation Happened to the Snow?

 

 

 

 

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This was how I felt yesterday…disappointed.  Disgusted.  Depressed…not really.  But maybe a little.  This was supposed to be our shot at a decent winter event.  The synoptic track was near-perfect.  Thermodynamics appeared very supportive of a winter weather event.  What happened?  I’m still wondering about that myself, and I’ll address that below.  This stanza is more about therapy.  After a missed, or a “busted”, event, I often find myself looking back and trying to understand what went wrong.  It’s how I deal with the agony of defeat.  Reliving the event, I’ve found, is very cathartic for me and affords me the ability to apply what I’ve learned to future events.  Some people have $200/hour therapists, I have a blog.  I’m already $200 richer.  #Winning.

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The Aftermath

Nationally, this storm put the hammer down across the Deep South.  From northern Mississippi, early Wednesday morning to central AL, northeast GA around dinner time, and up through the East Coast today, Winter Storm Pax (Weather Channel’s name, not mine) laid down a swath of snow and ice that would make the Ice Age proud.  Some totals from across the area:

Crossville – 6″

Chattanooga – 8-12″

Morristown – 7″

Totals across North Carolina and Virginia were nothing short of crazy.  If even half of those totals fell across Middle Tennessee, the midstate would be shut down until Spring.  Atlanta got hit with another ice storm, causing over 130,000 people to lose power Wednesday morning, and that was before the storm got ramped up. 

Here locally, the National Weather Service in Nashville received scattered reports of one-inch totals, mainly across the southern half of the county.  The northern half, I’m betting, didn’t see the first flake.  I know I didn’t.  That’s right…I went all day without seeing a single, solitary wet snowflake.  Now you understand the depth and magnitude of my depression.

The Lead-Up

As I’ve stated previously, the synoptic setup for this event was as favorable a setup as we’ve seen this entire winter.  We had a strengthening low across the Gulf of Mexico that was going to throw moisture northward into a thermodynamically-favorable airmass.  This was never going to be a huge storm by any stretch of the imagination.  The most favorable dynamics were always slated to stay to the south.  As such, the NWS issued a Winter Weather Advisory for most of southern Middle Tennessee – including Rutherford Co – for the expectation of 1-3″ of snowfall.  The numerical models supported this forecast.  Climatology supported this forecast.  The combined weather-forecasting experience contained inside the walls at Old Hickory were the foundation of this forecast.  So, what happened?

What Happened?

Mother Nature and Old Man Winter conspired to ruin everyone’s day, that’s what happened.  Well, not really.  It would be easy to place blame like that, but in reality, it’s not that simple.  Numerical models have been around for decades and are purposely built, maintained, and programmed to correctly foresee ripples in the meteorological universe that ultimately become systems that effect our weather.  Several days prior to the event, numerical models were insinuating that temperatures would be supportive of accumulating snowfall all day yesterday.  Virtually every global model (European, GFS, CMC) was in fairly decent agreement that temperatures would cooperate.  

As the number of days leading up to yesterday’s event lessened, a warming trend began to appear, leading many in the weather community to speculate as to what the models were seeing.  A day or two prior, a fellow weather hobbyist of mine, Justin Mundie, hypothesized that the result of these temperature anomalies were from downsloping winds coming off the Plateau into Middle Tennessee.  The physics behind that are rather difficult to explain, but, put simply, as an air particle decreases altitude, it warms up via an adiabatic process (a process that occurs without the transfer of heat or matter between a system and its surroundings).  Whether that original hypothesis was right or wrong, I’m not smart enough to dispel it.  After the moisture pulled out, Justin applied his own “debrief” of the event via Twitter (@justinmundie): 

“Debrief on what happened today: in short – I’m not sure. Short term models last night were showing a huge rise in surface temps.  I was sure about it as the global models had been consistent on temps being right at or below freezing. Obviously by this am, everyone knew it was going to be a concern. QPF came in about as was predicted, little if any north of I-40 – plenty south.  But with marginal surface temps, and marginal temps around 2000ft – the rate of precip wasn’t able to drag down cold air.  In fact – that dry, slightly above freezing air may have contributed to warming the surface – as precip wasn’t making it to the ground.  Another factor I believe was the cold air damming on the other side of te apps. Our cold high pressure was funneling cold east of the apps  All the way down to Atlanta – causing the severe winter storm they have seen today. That effectively cut off our cold air source.  So even with east/northeast winds, we weren’t able to keep temps cold enough for snow.”

With my limited knowledge of meteorology, and Justin’s knowledge of winter weather systems, I’m inclined to believe this hypothesis more than his previous iteration.  Some at the NWS hypothesized that the marked increase in progged surface temps could have been the result of increased solar angle and increasing solar insolation (the heating of the Earth’s surface by the sun).  I see no reason to doubt this hypothesis, either.  

Perfect Storm

So, it appears as though a perfect storm of inhibiting factors precluded us from getting a piece of 2014’s “perfect storm” across the South.  Snow is so inherently hard to get in Tennessee, whether it be by warm surface temperatures, imperfect storm tracks, or a blasted #SnowDome over Middle Tennessee.  Honestly, I’ve been quite skeptical of a #snowdome, but I’m a converted believer.  For my own sanity, I do hope this was the last winter weather system we’ll have to face across Middle Tennessee this season.  I love snow as much as the next person, but if I’ve got to sacrifice a limb to see fluffy, wet snow, I’d just assume pass.  

 

 

 

WIll it snow and how much?

We’ve been bypassed so many times here lately, with snow either to our north, to our west, to our east, and most recently to our south.  A report from Guntersville, AL said they received 6″ this morning.  6″??  Yeah, it chaps my rear end, too. 

Here’s the latest advisories/warnings:

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Rurherford Co is included in a Winter Weather Advisory.  Effects covered within this advisory include a chance of 1-3″ of snow accumulation.  There’s a distinct possibility that there could be a bit more than that, but there’s also the same possibility that there could be less than that.  Details below from our recently completed conference call with NWS Nashville:

– This forecast is arguably the hardest winter weather forecast these guys have seen in 5 or 6 years.

– Even at this hour (within 24 hours of an event), there are still model guidance diagreements.  Some models show little to no snow, while others show moderate to heavy snow.

– Precip will begin across N AL and overspread northward, initially starting out as maybe some sleet, but a quick transition to snow is expected.  

– There is a fairly high confidence that the greatest swath of heavier snow will be from a Pulaski to Lawrenceburg to Manchester line and southward, leaving those of us in Rutherford Co high and dry (figure of speech…)

– Biggest question is how far north does the snow get.  The air is really dry, not only at the surface, but higher up in the atmosphere.  The higher one goes, the “deeper” the dryness gets.  It’s going to take a while before the atmosphere moistens up enough to allow snow to fall.  Right now, the drier air is along and north of I-40, towards the Kentucky border.  We’re so close to being dry as well, but better positioned geographically to take better advantage of heavier precip rates.

– There will be a sharp gradient to snowfall totals, and even a single jaunt of 50-75 miles will have huge implications on amounts around the area.  

– Expect snow to arrive between 8-10am, with the heaviest snowfall to happen tomorrow afternoon.  I’ve already fielded questions about school closings/delays, and I just don’t have that information right now.  Another conference call is scheduled for 4:30am, and I’m sure that will be a major topic for discussion.

– Message to you #tspotters…the NWS has specifically asked that you help us tomorrow.  if you can tweet pics to us and tell us what you’re seeing, that will be fantastic.  You guys are a valuable resource to the weather community and our appreciation knows no bounds.

– Total accumulations for tomorrow, according to the NWS, will be 1-3″.  Some of you will see much less than that, but some could see a bit more.  Driving conditions will understandably go downhill once snowfall begins in earnest, and travel will be hazardous.

Winter weather update

Just concluded a conference call with NWS Nashville, and here are the highlights:

– Model uncertainty remains, with temperature profiles within the atmosphere being the main hiccup.  A degree or two either way can – and often does – have huge implications on precipitation type across the area.

– Current thinking is, the favored “snow belt” of Tennessee (areas NW of Nashville from Camden-to-Big Sandy-to-Clarksville-to-Portland) stands the best shot at measurable snowfall.

– The surface freezing line will takes it sweet time reaching us from KY.  Maybe it’s enjoyed a little too much Kentucky bourbon during it’s pre-Super Bowl party.  Somebody find it a designated driver.

– It appears that from the CURRENT model data, the predominant precip type for areas along I-40 will be ice.  Again, every degree will make a difference, so that could change later this afternoon/evening.

– Expect ice accumulations up to 1/4″ and some minor sleet accumulations.  Ground temps are relatively warm, but exposed surfaces will be the first to glaze up.  Travel could be an absolute mess come Monday morning.  However, anything that does fall will be gone by Monday afternoon as temps moderate.

Stay tuned for further updates as they happen.  We now return you to your regularly scheduled programming.