Jan 22-23 Winter Storm Event..."The Middle Tennessee Mauler"

[John1122]

Eps Text means from superjames in the SE forum including Wednesday. Would like to see Crossville and Tri.

 

 

Anyways, the 12z EPS bar graphs are out and up across the board, for those interested:

 

CHO: 20.0"

IAD: 17.5"

RNK: 16.5"

DCA: 16.0"

MWK: 12.25"

AVL: 11.5"

HKY: 10.0"

GSO: 7.25"

TYS: 4.5"

BNA: 3.75"

GSP: 3.25"

CLT: 2.9"

RDU: 2.7"

PGV: 1.1"

HSV: 0.7"

ATL 0.2"

BHM: 0.2"

CAE: 0.15"

[tnweathernut]

Plug for the Americanwx model suite.  Good stuff and you can see the pretty snow maps too.  I highly recommend you join if you haven't already.  It's only 10 bucks a month!

I wanted to compare the last two snow maps from the parallel GFS runs. (6z and 12z).  You can definitely see an uptick in the amount of snow the model is seeing (even though it looks like poo poo at the surface for east TN we score on the wrap around)

 

[Carvers Gap]

I'm not sold on any of them really, but the GFS has been much better than the Euro over the last few events. It blew the Euro out of the water in this range for the last storm that passed South of here. The GFS missed the track by about 100-150 miles at this range, the Euro missed it by 600 miles.

 

And both were erroneous in sending too much energy west of the Apps.  But in general, the Euro has scored much better than the GFS this winter.  Have not seen the verification scores for the past week.  The GFS had some company last week...not so much this week.  But hey, it could score a coup.  Again, like you...not trusting much until the energy is over NA.  I will add to your point that the Euro busted big time over NC w/ the "blizzard that never was"  last winter.   Hey, if you have a link to the verification for the models...that would be much appreciated. 

[JayCee]

The mean has improved each of the last five runs.  The EPS takes the primary up through w TN.  Then, a small reflection of that low finds its way into SE TN.  So, you ask...how does it improve w/ snow totals in the eastern Valley compared to 0z EPS mean?  It transfers energy earlier and more to the SE.  The 0z EPS secondary low formed just to the sw of Hatteras.  The 12z EPS secondary low forms over SC.  Thus, it allows for more snow to fall over the middle and northern sections of the eastern Valley.  So, the earlier transfer of energy offsets the low going into western TN - for the eastern Valley.   As for the western Valley, this has never really been its storm.  Minus a few runs here and there this storm has really been and eastern Valley "chance."  Pretty crazy watching a system transfer energy to South Carolina.  Now...keeping it level...once the energy hits the coast(soon) we will have a much better picture of what happens.  Still think there are some things that will change...good or bad until that "better" data is ingested.   

Enjoying the discussion and insight here. 

 

I have a quick question--when you say western vs eastern Valley exactly what part of the valley system are you referring to?  Are you referring to Tennessee only--as in west and south of Knoxville verses areas closer to the Mountains? Or are you referring to the whole TN valley region that includes all of TN and parts of Alabama?

[John1122]

Enjoying the discussion and insight here. 

 

I have a quick question--when you say western vs eastern Valley exactly what part of the valley system are you referring to?  Are you referring to Tennessee only--as in west and south of Knoxville verses areas closer to the Mountains? Or are you referring to the whole TN valley region that includes all of TN and parts of Alabama?

 

When I'm talking about it in this thread I am referring to Northern Alabama to Northern Miss up to SC/SW Kentucky.

[Carvers Gap]

Enjoying the discussion and insight here. 

 

I have a quick question--when you say western vs eastern Valley exactly what part of the valley system are you referring to?  Are you referring to Tennessee only--as in west and south of Knoxville verses areas closer to the Mountains? Or are you referring to the whole TN valley region that includes all of TN and parts of Alabama?

 

To echo John, the TN River as it goes between west and middle TN river. Eastern Valley is the eastern side of the U formed by the TN river.  Cool fact.  The TN River is one of the few rivers in the lower 48 that flows northward.  Thus, creating the horseshoe...

 

[John1122]

18z stood it's ground with the dynamic system. Really piled up snow in NW Tennessee, the Plateau and NE Tennessee that run.

[Carvers Gap]

18z stood it's ground with the dynamic system. Really piled up snow in NW Tennessee, the Plateau and NE Tennessee that run.

 

Was a good run for much of TN for sure.  The slp is weaker as it rolls through the Valley, less expansive as well. But it is a bit wonky.  Versus having a good, continuous swath of snow...it is made up of blobs where the GFS seems to leave a piece of energy too long.  As an example, it leaves a piece of energy sitting in NE TN for a decent amount of time.  If that feature is absent...1-3".  Same is true for NW TN.  The main thing that catches my eye, the EC storm is a bit westward along the NE coast.  What that means on this run is that the axis of snow is less of a slider and more up the coast, pivoting the storm a bit more over the eastern Valley.  And again, my main concern is that really no other model shows the west TN accumulations.  That said, when one looks at the Euro it would seem that it is missing some accumulation west of the Apps.  So, maybe the GFS is just picking-up on that.  Maybe the GEFS will help.  And last but not least, it is the 18z and it can get a bit crazy.

 

edit:  It is not too far off the Euro ensemble mean... It had a lot of accumulation along the TN/KY border.

[John1122]

Was a good run for much of TN for sure.  The slp is weaker as it rolls through the Valley, less expansive as well. But it is a bit wonky.  Versus having a good, continuous swath of snow...it is made up of blobs where the GFS seems to leave a piece of energy too long.  As an example, it leaves a piece of energy sitting in NE TN for a decent amount of time.  If that feature is absent...1-3".  Same is true for NW TN.  The main thing that catches my eye, the EC storm is a bit westward along the NE coast.  What that means on this run is that the axis of snow is less of a slider and more up the coast, pivoting the storm a bit more over the eastern Valley.  And again, my main concern is that really no other model shows the west TN accumulations.  That said, when one looks at the Euro it would seem that it is missing some accumulation west of the Apps.  So, maybe the GFS is just picking-up on that.  Maybe the GEFS will help.  And last but not least, it is the 18z and it can get a bit crazy.

 

edit:  It is not too far off the Euro ensemble mean... It had a lot of accumulation along the TN/KY border.

 

Actually the heavy blobs appeared to be areas that the model had under really really heavy rates as the storm rolled across the state. I'd take it's output and smooth it a bit if I were going to attempt to go by it's map. Still a long way from the final chapter being written though.

[JayCee]

To echo John, the TN River as it goes between west and middle TN river. Eastern Valley is the eastern side of the U formed by the TN river.  Cool fact.  The TN River is one of the few rivers in the lower 48 that flows northward.  Thus, creating the horseshoe...

 

tn valley.JPG

 

Cool.  Thanks for the clarification. 

[John1122]

Joe B on the Euro.

 

 

euro is making mistake on upper low in my opinion

that upper low should lift to over the Delmarva. I think this is an error here

132 the upper feature is likely to be near the mouth of the Delaware not reforming to the south. Put it this way, I dont recall seeing something like this. Once the feedback starts, the storm should pull the upper feature in, so a deeper upper feature at the north side of the elongated feature is what I think we see

at 192, expect a single deeper feature over the central Appalachians, not the Euro split

 

 

The implication of the first part is just picking out details. I believe this storm and then the next will in many cases put people from the Tenn valley ne into New England ahead of the snow pace for our forecast, and in some cased will mean the seasonal idea is already attained.

[Carvers Gap]

Actually the heavy blobs appeared to be areas that the model had under really really heavy rates as the storm rolled across the state. I'd take it's output and smooth it a bit if I were going to attempt to go by it's map. Still a long way from the final chapter being written though.

 

Yeah, in E TN it was like it finally recognized a heavy band associated w/ the comma head.  Totally agree that this chapter is not written.  Good discussion to you and the other folks of the TN Valley forum.  Heading to help coach basketball practice. Hopefully somebody in this forum will have had a pretty good week by next Sunday.

[Runman292]

Joe B on the Euro.

What does the bolded mean?

[John1122]

What does the bolded mean?

If you're talking about his Tennessee valley comment, he predicted 200% of normal snowfall if I remember correctly. He seems to be saying that could be fulfilled within the next two storms.

[weathertree4u]

If you're talking about his Tennessee valley comment, he predicted 200% of normal snowfall if I remember correctly. He seems to be saying that could be fulfilled within the next two storms.

Yes he did and yes it could be if they both occur as modeled, personally, it has been since I was a kid in late 1980's that Nashville had enough snow to plow, perhaps we can actually use the plows this year!

[tnweathernut]

I believe he's talking about three events, but what he thinks will be two major events (late week and next week). He always swings for the fences though, I'd prefer concentrating on the 1-3 chance we have right in front of us for Wednesday though.

[dwagner88]

Yes he did and yes it could be if they both occur as modeled, personally, it has been since I was a kid in late 1980's that Nashville had enough snow to plow, perhaps we can actually use the plows this year!

That can't be right.

[Carvers Gap]

If you're talking about his Tennessee valley comment, he predicted 200% of normal snowfall if I remember correctly. He seems to be saying that could be fulfilled within the next two storms.

He catches a lot of heat (some of it rightfully so), but I like him. He does a good of of explaining things. WxSouth is another good one. Also, I like DT. Of course Mr and Jeff. And if WxS and JB bust, they bust...but those guys really went out on a limb. They had some pretty sound reasoning. So, on a personal level I hope they score even if I have my doubts.

[John1122]

That can't be right.

 

I believe Nashville had a 7 inch snow in March 2003 and a 9 inch snow in January 1996. Most of Nashville's top snow events are November, February and March events. None of their top 7 snows of all time were in January. So events greater than 6 inches in January don't happen very often there.

[John1122]

Not the best run of the GFS. System wasn't as strong, so the back side snows weren't as good. Maybe 2-3 inches at best outside the mountains.

 

At 12z and 18z the 500mb vort went right over us and it was wound up pretty good. On this run the 500mb vort wasn't as wound and went right over Kentucky. Thus the different result.

[John1122]

[John1122]

I may be seeing it wrong, but it looks like the Euro downslopes NE Tn and just dumps on the Western Plateau/Highland rim East of Nashville with that run. Also really pounds NW Tennessee.

 

Actually the clown probably looks similar to the GFS clown from earlier that had NW Tn, the Plateau and Mountains getting pounded.

 

About 6 more Euro runs and 10 more GFS runs to nail this one down.

[John1122]

06 stuck with the less favorable 500mb vort track and still shows 2-3 inches additional accumulations for most of us rather than the 5-8 it was advertising. This one should start getting more clear by tomorrow's runs. Wave will be on shore and the system for tomorrow will be pulling through.

[Carvers Gap]

The GFS, NAM at long range, and GEM have similar set-ups in that they drive the primary into se KY.  The Euro, JMA(yesterday...have not seen this AM's), and UKMET have a weaker primary.  The EPS and Canadian ensemble transfer the energy sooner.  The EPS mean and control all show increasing snow amounts across the northern border and NE TN.  The EPS ensembles are less favorable for nw TN than the operational.   Some of that is courtesy of tomorrow's system.  The Euro is basically the same as yesterday and has been locked on this system for days.  The GFS solution at 0z and 6z is a new twist.  Once inside 84, I am not sure I give any model the edge...but how quickly and "where to" that energy transfers is important west of the Apps.  The EPS secondary forms over SC.  The GFS is well north of that if I remember correctly.  12z should be an interesting run for sure. 

[tnweathernut]

The storm should be well sampled at 12z today.  Let's see if there are any noticeable changes with regards to primary vs secondary.  One thing I noticed was the wedge east of the mountains is getting stronger every run it seems.  That won't help us, but a Miller B where the primary doesn't make it into Tennessee and transfers to the SC coastal area might help keep max temperatures in check for parts of the northern valley.  It would mean the difference between a lot of coldER rain vs plain old cold rain (45 or 36) for northeast TN... haha

[Carvers Gap]

MRX has another great write-up this this AM.  Here is an excerpt.  Model trends for the Valley will be important today.  We have always been on the edge of some pretty good snows and still are.  But not there yet.  Three things to watch for today...

 

1.  Where does the primary go?  How far north and east does it actually go into TN?

2.  When does the energy transfer?

3.  Where does it transfer to?  We need it to be just inside of the coast in South Carolina and Georgia.

4.  How strong is the secondary?  One can see on the GFS what happens if the secondary is weak.

 

Also, w/ the system that arrives tomorrow...it appears to be further south than the original GFS look and stronger than either the Euro or GFS forecast.  Seems like they underestimated the strength of the northern feature and the GFS underestimated the high/blocking to the north.  Might be something to consider as we see the models at 12z in regards to system 2.  Here are the MRX comments for TR/FR....

 

NOW OUR ATTENTION TURNS TO THE NEXT SYSTEM WHICH MODELS SHOW TO
BE MUCH STRONGER THAN WEDNESDAY`S EVENT. MUCH UNCERTAINTY STILL
EXISTS WITH THIS SYSTEM DUE TO THE EXACT TRACK. KEEP AN EYE ON THE
FORECAST BETWEEN NOW AND THE EVENT AS DETAILS WILL BECOME CLEARER
WITH TIME. AS OF NOW...MODELS SHOW A LOW PRESSURE SYSTEM DEVELOPING
TO OUR WEST AND INITIALLY SPREADING RAIN INTO OUR AREA BY THURSDAY
AFTERNOON AS SOUTHERLY WINDS TRANSPORT MOISTURE AND WARMER TEMPS
INTO THE AREA. HIGHS ON THURSDAY WILL BE IN THE LOW TO MID 40S.
RAIN CONTINUES OVERNIGHT THURSDAY AND INTO FRIDAY AS WE ARE STILL
IN THE WARM- SECTOR. AS THE LOW PROGRESS EASTWARD WINDS WILL SHIFT
AND COLD AIR WILL START TO POUR IN ON THE BACK SIDE OF THIS SYSTEM.
ALSO...850 MB WINDS WILL SHIFT INTO A FAVORABLE DIRECTION FOR
POSSIBLE MOUNTAIN WAVES FOR A BRIEF PERIOD ON FRIDAY...WHICH IS
MENTIONED IN THE HWO. RAIN CONTINUES THROUGH MUCH OF THE DAY ON
FRIDAY BEFORE EVENTUALLY CHANGING OVER TO SNOW. SNOWFALL AMOUNTS
DEPEND ON HOW QUICK THE CHANGEOVER OCCURS AND HOW MUCH MOISTURE
LINGERS. MODELS DUE SHOW QUITE A BIT OF LINGERING MOISTURE FROM
FRIDAY NIGHT THROUGH SATURDAY. SOME AREAS LOOK LIKE THEY COULD SEE
SEVERAL INCHES OF SNOW OUT OF THIS SYSTEM...ESPECIALLY ACROSS NETN
AND SWVA. OUR FAVORED HIGHER ELEVATION AREAS COULD SEE SIGNIFICANT
SNOW AMOUNTS. SNOW TAPERS OFF SATURDAY NIGHT AND SUNDAY LOOKS DRY
AS THE LOW DEPARTS TO OUR EAST. THEN ANOTHER SYSTEM MOVES IN FOR
MONDAY BUT IT LOOKS TO BE ALL RAIN AT THIS TIME.

[Carvers Gap]

Here is DT's update from FB...I did not include maps since we have been asked not to post Euro pay maps.  But a good discussion on the differences in modeling.  Though, he mentions the GFS is on an island in its handling of things in the MA...I am not sure that translates to it making mistakes over the TN Valley earlier in the run.  

 

 

 

[Carvers Gap]

From WPC...excerpt.  This event is interesting just from a wx standpoint.  It has the potential to be a BIG storm.  If not for us, then somewhere else.  Anyway, this WPC discussion is not from a wx hobbyist like myself.  These folks do it for a living.  Also, I will provide the link as it also has some info on tomorrow's system.  So, I think it adds some validity that we aren't just talking about a wishcast.  Again, we are still right on the edge of some nice snows, but not there yet IMO.  But WPC does mention our region, so it gets my attention.

 

http://www.wpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=qpfhsd

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSIONNWS WEATHER PREDICTION CENTER COLLEGE PARK MD432 AM EST TUE JAN 19 2016VALID 12Z TUE JAN 19 2016 - 12Z FRI JAN 22 2016DAYS 1 THROUGH 3...

THEN ON THURS... UPPER STREAMS WILL TRULY BEGIN TO PHASE OVER THELOWER MS VALLEY AND LEAD TO A DEVELOPING WINTER STORM. THE MID TOUPPER LOW AND VORTICITY WILL DIG SOUTH AND EAST TOWARD AR/NRN MSTO ESTABLISH AN AMPLIFIED UPPER TROUGH OVER THE LOWER MSVALLEY/CENTRAL GULF COAST STATES. THIS AMPLIFICATION WILL ALLOW APLETHORA OF GULF OF MEXICO AND SUBTROPICAL MOISTURE TO SPREADNORTHWARD... BEGIN INTERACTING WITH A DEVELOPING AREA OF LOWPRESSURE AND OVERRUN INTO MODIFIED ARCTIC AIR MASS. THE RESULTANTWILL BE A WIDESPREAD AREA OF HEAVY SNOW AND LENGTHY TRANSITIONZONE FROM SRN MO/NRN AR UP THE OH RIVER INTO KY/WV AND INTO THEAPPALACHIAN SPINE WHILE SPILLING OVER EAST OF THE MTNS INTO SWRNVA/WEST CENTRAL NC.ITS HARD TO ARGUE THE AGREEMENT AND LITTLE SPREAD BETWEEN THEHI-RES GFS AND ECMWF ON THE DEVELOPMENT OF THIS POTENTIAL WINTERSTORM THROUGH THURS... MASS FIELD WISE WITH SMALLER SCALEPARTICULARS ALONG WITH QPF AND THERMAL PROFILES... ESPECIALLYGIVEN THIS WOULD BE THE FIRST PHASING EAST OF THE ROCKIES SINCELOCKED INTO THIS CLASSIC EL NINO PATTERN.BEYOND THE FCST PERIOD AND INTO THE MEDIUM RANGE... A 48-60 HRWINDOW EXISTS FOR A POSSIBLE HISTORIC WINTER STORM FROM THE ERNOH/TN VALLEYS INTO THE NRN MID-ATL REGION INCLUDING THEDC/BALT/PHIL METRO AREAS. TREMENDOUS MODEL AGREEMENT WITH MINIMALMODEL SPREAD IS INCREASING THE FORECAST CONFIDENCE FOR SUCH ANEVENT. A QUICK LOOK INTO ANALOGS SUGGEST THE MOST RECENT EVENTRELATIVE TO THIS SETUP BEING 20 YRS AGO IN JAN OF 1996 THOUGH WITHSOME DIFFERENCES. MUCH NEEDS TO BE FIGURED OUT TILL WE GET TO THATPOINT BUT THIS COULD BE THE MOST WIDESPREAD WINTER STORM OF THESEASON.MUSHER

[Greyhound]

That last paragraph sure does get me drooling.  Carvers.....thanks for all the info you post on here!!

[Carvers Gap]

That last paragraph sure does get me drooling.  Carvers.....thanks for all the info you post on here!!

 

For sure, but I am not sure how I feel about their statement either.   I am reading through their other discussions.  They really like the 18zGFS in their model discussions which FWIW had depended heavily on backside snow for any accumulation w/ system #2.  The Euro has more historical amounts.  But yeah, was not expecting that and really no model that I have looked at looks historical in terms of snow amounts for anyone in the Valley, east or west.  But thought it was worth sharing.  Interesting to see the '96 analog show up.  BTW, most folks use analogs not as the end all be all...but just to make sure that what the models are doing makes sense.  So, if this set-up has been seen before...then it helps w/ confidence levels if the current models are showing a similar result. 

 

Truly, I am following this because it is one of those events that we may potentially not see very often...that does not mean we get a flake here, but we can learn from it.