December 8-10 Storm Discussion

[AMZ8990]

5 minutes ago, John1122 said:

FV3 still a big hitter almost statewide but the northern edge of the precip is further south and totals shrank overall through 78 but it's still snowing in Eastern areas. Skipped 84 so not sure if it was still snowing then or not.

Yeah your right, FV3 just won’t budge!!  I hope it’s right. Lol  

[Holston_River_Rambler]

I wonder if what we may be seeing here is the transition from a the models showing a Miller A/B hybrid to more of a pure Miller A. The lowered totals may be from the fact that there's less front end thump as the system initially starts further south, but then we may get more from the deformation areas as the mid level lows trend further south?

By the way the RGEM at the end of its run looks like it could be snowy for some of the areas it shows rain. Those yellows and oranges mixed with deep blues are in areas where the 850 and 700 mb temps are below freezing and surface temps in the mid 30s. 

[Holston_River_Rambler]

Stole this image from the SE forum. RGEM at hour 54 accumulations, with more on the way. Ratios would be off, but still...

[Carvers Gap]

NE TN and SW VA folks...

Definitely a concerning trend to reduce precip total northwest of the Apps.  Our forum has done awesome w that trend...some forums go to pot when a bad trend shows up.   So here are my thoughts.  Not trying to be a pumper or a downer:

1.  The global models saw a big jump at 0z southward.  The GFS continued this at 6z.  The FV3 is still in our camp along w the CMC and Navgem regarding precip.  Shaky company!  I am not sure what caused the move.  Maybe the feature in the northern stream is better modeled now?  Maybe the highs over the top are placed a hair south or are a hair stronger.  I noticed that their placement is a mb or two stronger on some of the runs(can't remember which).  I noticed they were a tad colder.  They definitely are flatter.  Maybe the storm that just let NA has not departed quickly enough and is forcing everything south? 

2.  Looking at the MA, storms there have a habit of jogging south on models before the storm only to correct north.  What research do I have to prove this?  Human behavior.  I have seen folks in DC pull their hair out while Richmond appears to be in good shape.  Next thing you know, Richmond is mix w lower totals and DC gets hammered.  I wonder if we begin to see a trend north at 12z or 0z.  No idea.  Right now, the trend is definitely south towards the realm of Nothingburger.  Let's hope we don't go there.

Bout it.  The RGEM does look good.  The NAM looks good but corrected south.  Navgem and CMC look ok as does the FV3.   But trends do matter, and those were not good trends at 0z.  Not going to sugar coat it.  If those trends continue at 12z(reduction in precip), going to be a tough sell for significant snow or any snow at all.

Last parting thought...it is possible that the northern precip shield is being poorly modeled...as in not enough precipitation.  Also, I do not trust the GFS right now.  It caught the trend.  But my eyes are on the 12z Euro to see if it balks again.  The 0z will matter as well later tonight.

[Carvers Gap]

8 minutes ago, Holston_River_Rambler said:

Stole this image from the SE forum. RGEM at hour 54 accumulations, with more on the way. Ratios would be off, but still...

On that run, it was barely even in NE TN yet - would have been a great run if it went out further (edit).  I do like having the RGEM in our back pocket.  I think global trends are concerning...so that does give me some hope.  Nice share.

[EastKnox]

6z Euro

[Carvers Gap]

The 6z GEFS mean looks about like that 6z Euro.  I think at this point we can call that a trend.  No sugar coating it. 

[EastKnox]

5 minutes ago, Carvers Gap said:

The 6z GEFS mean looks about like that 6z Euro.  I think at this point we can call that a trend.  No sugar coating it. 

Not looking good.  It looks like the LP slides OTS without making much of a pivot northward.  And sorry for holding out on the 6z/18z Euro.  I just realized I have access this morning.  They go out to 90h for most products and 144h for others.  

[AMZ8990]

Looks like it’s gonna be a boom or bust weekend for most of us.  Still plenty of time for variables to change the outcomes but It’s looking more likely this will be a nowcast event though.  

[TellicoWx]

The 850 vort has been shifting south, we lose the lift it provided across the northern area and allows the downsloping to really eat away at everything. The highs being a tad stronger allows even more drying as it reaches further south. Basically it loses its characteristics as a miller B or hybrid from what I can tell.

[tnweathernut]

Trends aren’t good, but there is some hope.  Modeling in the 36-72 range will usually have an undermodeled northern edge.  I have seen precio verify regularly northwest of modeling on southern traversing systems with gulf interaction.  Not good, but not totally dead either.

[Holston_River_Rambler]

Kind of echoing what you just said, now I wonder, with the swifts south, do we get a NW trend at the last minute as the mid level lows get to, let's say the AL/GA line, or no?

Besides the snow totals, I think the biggest trend long term for this system has been for the track to be more of a SW to NE, instead of an E to W.

I'm hugging Feb 2015 right now, not the same system or set up, but hoping for similar last minute trends:

 

[Jed33]

An example of the precip shield extending further north of modeling may currently be seen on radar. It looks like the north side of Chattanooga and the county east of it may be experiencing some snow based on radar. Of course it may just be virga. At any rate, I don’t see the precip field that expansive on any computer model.

[BlunderStorm]

Well I've went from expecting 6-10 inches to nothing over the course of 6 hours. To tell you the truth I think this is all she wrote.  Not a lot to add atm that you guys haven't already said.

[ShawnEastTN]

@Jed33@Holston_River_Rambler@tnweathernut Absolutely, I wouldn't tap out completely yet, we see this frequently year to year where a storm's northern precip shield is vastly under modeled, on one hand if that is the case and there is more dry air in northern areas (stronger and or further south High), could help with evaporational cooling for many in northern fringes.

To me a tick south at this stage in the game isn't a bad thing.  The FV3 is still generous.

[TellicoWx]

1 minute ago, BlunderStorm said:

Well I've went from expecting 6-10 inches to nothing over the course of 6 hours. To tell you the truth I think this is all she wrote.  Not a lot to add atm that you guys haven't already said.

While the trends haven't been great, we are still outside the mesoscale models wimdow. With so many microclimates in East TN, won't completely write off this storm at least the next 24 hr model cycle.

[Chattownsnow]

1 hour ago, Jed33 said:

An example of the precip shield extending further north of modeling may currently be seen on radar. It looks like the north side of Chattanooga and the county east of it may be experiencing some snow based on radar. Of course it may just be virga. At any rate, I don’t see the precip field that expansive on any computer model.

I had some sleet mixed with rain but very light. 

[BlunderStorm]

Latest NAM 12km compared to the last two runs before it at 48 hours. 

[Holston_River_Rambler]

 

[nrgjeff]

Ditto Friday morning in East Brainerd @Chattownsnow and @Jed33 a few pings of sleet on car; otherwise, light rain. Morning @Holston_River_Rambler thanks for the 2014 and 2015 memories!

OK the forecast. Tough to sugar coat the ECMWF and ICON overnight. Oh but they do still have powdered sugar, snow at/north of I-40. Lower QPF is one problem which impacts another problem, less cooling of the column. Silver lining is a little farther south vort max. Only in the South could that improvement actually hurt the low levels. As others have written, it could still work out. Precip shield could verify north of progged.

I am not as concerned about ice as some. Low levels are a bit warm. In some areas (West KY, Northwest Tenn) 850/925 mb drops below freezing before the surface, no ice. Many areas they are close, which is only a little ice. Global NWP shows some 0 surface,+2 aloft, ice northeast Tenn. However short-term high-res NWP has 850/925 colder faster; so, maybe not much ice. Still early to bank on high-res at 36 hr but my gut does not feel so much ice.

Added: Now just a few inches of wet snow on top of .10" ice would be an issue. Normally I do not get concerned below .25" ice, but wet snow is forecast too. Thinking out loud, while I'm not expecting much ice to ruin the snow show where it snows, trees might be a little stressed.

Southwest Virginia very likely will get snow. One can relax a bit up there regardless of models.

Could be my last quality post, but we will see what 12Z data brings. Hvward is too high Tenn. Hvward is usually money in NC though, very good forecaster. I might take a stab at amounts later.

If chasing snow, I'd try to get into a NC ski area. Not sure if they are opening but it'll be pretty!

[Windspeed]

0z NAM was the sweet spot for NE TN/SWVA region. 06z and 12z NAM is caving to the more southerly suppressed trend as well now. The 850-700 mb feature advancing out of E TX/Ark/W TN that was very evident on previous runs just isn't as strong versus stronger heights over Ohio Valley and New England. Still time to swing back but clearly the trend remains South for this system:

[BlunderStorm]

Well it's going to take a miracle. I'll be looking for any last minute jogs north on the modeling for the next 18 hours. When there is less than 24 hours until the event I'll shift to watching the radar and the occasional HRRR model run. Folks at my school are confused with some people mumbling about 2 feet of snow and others mumbling of none and everything in between haha!

[Freezing Fog]

[BlunderStorm]

12 minutes ago, Freezing Fog said:

I'm not sure if I should like this for it's relatability. Send a laugh reaction for the irony.  Say thanks for summing my thoughts. Consider myself as confused regarding trends. Or put a sad reaction for the harsh reality of the situation! Ah, I think I will go with laughing! xD 

[tnweathernut]

MRX isn't giving up just yet. 

URGENT - WINTER WEATHER MESSAGE
National Weather Service Morristown TN
952 AM EST Fri Dec 7 2018

...A STRONG EARLY SEASON SYSTEM WILL BRING THE POTENTIAL FOR A
SIGNIFICANT SNOWFALL ACROSS SOUTHWEST VIRGINIA AND NORTHEAST
TENNESSEE SATURDAY NIGHT THROUGH MONDAY...

Widespread precipitation will move into the area Saturday as a
strong low pressure system approaches the area. Temperatures will
be cold enough across northeast Tennessee and southwest Virginia
for precipitation to begin as a mixture of rain, snow, and sleet
in lower elevations, with mainly snow in the mountains. The best
lift and moisture will arrive on Saturday night and continue
through Sunday, with significant snow accumulations possible.
Snow will begin to taper off on Monday.

TNZ014>017-042-044-046-072300-
/O.CON.KMRX.WS.A.0002.181209T0000Z-181210T1700Z/
Claiborne-Hancock-Hawkins-Sullivan-Northwest Greene-Washington TN-
Northwest Carter-
Including the cities of Tazewell, Sneedville, Rogersville,
Kingsport, Bristol, Greeneville, Johnson City, and Elizabethton
952 AM EST Fri Dec 7 2018

...WINTER STORM WATCH REMAINS IN EFFECT FROM SATURDAY EVENING
THROUGH MONDAY MORNING...

* WHAT...Heavy snow possible. Total snow accumulations of 4 to 8
  inches possible.

* WHERE...Lower elevations of northeast Tennessee including the
  Tri-Cities area.

* WHEN...From Saturday evening through Monday morning.

* ADDITIONAL DETAILS...Travel could be very difficult to
  impossible. The hazardous conditions could impact the morning
  commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

[Holston_River_Rambler]

12z RGEM says “suppression? What suppression?”

warm nose partly into SW VA based on snow maps. 

[BlunderStorm]

The NAM 3km says hold on a second and stays similar to 6z.

[Carvers Gap]

You know...the NAM looked flat and slightly less organized from the start.  Well if we whif on this, it was all bonus.  We are rarely tracking this time of year.  We are already on our second storm thread!  And the good news is that the LR looks good during prime tracking time around the New Year and into January.  If the trends continue, we can all sing Kumbayah together...would probably go down as one of my favorite bust threads.  Plenty of posters and some new folks.  I will probably wait until 0z before moving on.  Read my MA comment earlier about storms jogging north at the last minute and that is why.

[ShawnEastTN]

Just now, Carvers Gap said:

You know...the NAM looked flat and slightly less organized from the start.  Well if we whif on this, it was all bonus.  We are rarely tracking this time of year.  We are already on our second storm thread!  And the good news is that the LR looks good during prime tracking time around the New Year and into January.  If the trends continue, we can all sing Kumbayah together...would probably go down as one of my favorite bust threads.  Plenty of posters and some new folks.  I will probably wait until 0z before moving on.  Read my MA comment earlier about storms jogging north at the last minute and that is why.

That famous north and west jog used to always be prevalent in the last 24 to 48 hour window of modeling. 

[Carvers Gap]

5 minutes ago, Holston_River_Rambler said:

12z RGEM says “suppression? What suppression?”

warm nose partly into SW VA based on snow maps. 

LOL.  To steal a funny quote from Bob Chill...I may just find the snowiest model and hug that one.  The RGEM sounds like a candidate!