February/March 2020 Winter's Last Chance Thread

[Carvers Gap]

Just now, Holston_River_Rambler said:

Along those lines, and maybe I'm misremembering, I feel like this storm got booted out of the SW quicker than the Euro originally wanted it to. Looking at the overnight Euro, if you get that shortwave to roll east a little faster, and the northern stream verifies a little faster then you get something more akin to the GFS solution. 

Yeah, I think the Euro buried the current trough in the Southwest on one or two runs and never ejected it.  In reality...it did dig, but it came on out.  These runs where they dig, sit/spin, and dig a western trough are a bit suspicious.  Again, the MJO does call for a SER and troughing in the West.  Originally, we thought this would be a more progressive pattern with the cold pressing East at times.  It may be that we are just in a base warm pattern where the cold presses at times vs a total shut-out pattern.  Not sure.  

[Carvers Gap]

3 minutes ago, Holston_River_Rambler said:

By "this storm" I mean how the current one was forecast at range

I understood and agree.

[Holston_River_Rambler]

Been trying to dig though my gifs for a OP Euro of this one at 200+ range, but no dice. 

[Carvers Gap]

So, the CMC and GFS at 12z have a similar setup:  big highs that are pressing south and east and a gradient type storm late next week.  IMHO, gradient storms can be super difficult to find where the snow line sets-up.  Some years, those gradient storms are further south than depicted.  Have seen several I though twould hammer MBY in years past, and they went to the GC.  Seems this year they might verify north of modeling at this range due to modeling cold bias.  So, we want to see that trend southward and then come back IMHO.  But again, tricky to work out.

[Carvers Gap]

But I think we can say this...very active precip pattern with potential for cold fronts during the 10th-20th which is far better than I expected earlier in the week.  

[TellicoWx]

Folks in the southern valley/N Ga may wanna keep an eye on the disturbance rotating thru overnight/early morning timeframe tonight. Most modeling squeezing out decent chance of snow showers. Haven't got to look at the thermal soundings.

[Carvers Gap]

Just now, TellicoWx said:

Folks in the southern valley/N Ga may wanna keep an eye on the disturbance rotating thru overnight/early morning timeframe tonight. Most modeling squeezing out decent chance of snow showers. Haven't got to look at the thermal soundings.

Good call, 3K NAM looks decent in those areas.

[TellicoWx]

2 minutes ago, Carvers Gap said:

Good call, 3K NAM looks decent in those areas.

3K, HRRR, and RGEM all showing a little something 

[Carvers Gap]

Just now, TellicoWx said:

3K, HRRR, and RGEM all showing a little something 

Yeah, I had quit watching that system closely because it had weakened so much.  There are some decent lollipops on those maps.  Those little systems are fun to track.  .  

[TellicoWx]

RAP is the furthest north of the 4, and plays down a good bit along the TN/GA border.

[Holston_River_Rambler]

UKMET for tomorrow

[Carvers Gap]

Just now, TellicoWx said:

RAP is the furthest north of the 4, and plays down a good bit along the TN/GA border.

When is that moving in tomorrow?  Would be awesome for the SE TN folks to finally have something to track.  Been truly rough sledding there.  

[Holston_River_Rambler]

1 minute ago, Carvers Gap said:

When is that moving in tomorrow?

UKMET has it between 12 and 18z tomorrow 

[TellicoWx]

1 minute ago, Carvers Gap said:

When is that moving in tomorrow?  Would be awesome for the SE TN folks to finally have something to track.  Been truly rough sledding there.  

Yeah overnight into the morning hours...slight timing differences maybe in each model, but that's the general consensus 

[Carvers Gap]

One last thing in the LR and I will try to keep from cluttering the thread with LR posts since we have something tomorrow to track tomorrow, @holston the GFS has an Aleutian pattern that has low after low in that area....just one right after another.

Also, definitely fun tracking stuff that pops back up in the short range.  

[TellicoWx]

2 minutes ago, Holston_River_Rambler said:

UKMET has it between 12 and 18z tomorrow 

Agrees with the others..think the RAP was the fastest breaking out snow over N MS before sunrise.

[Holston_River_Rambler]

Tomorrow could be a fun one of those systems where a little extra RH gets sucked up the valley and lifted in the foothills areas

[TellicoWx]

Suprising, looking at all the thermals...temps are right at or below 32

[TellicoWx]

3 minutes ago, Holston_River_Rambler said:

Tomorrow could be a fun one of those systems where a little extra RH gets sucked up the valley and lifted in the foothills areas

I wonder if all the ground moisture still around could also squeeze a little mor moisture in the very lowest levels from the evaporation taking place.

[Carvers Gap]

Cause you know I am going to be driving the family van down from the Plateau tomorrow around 18z...so we know this is going to verify.   LOL.  

[Holston_River_Rambler]

Looks like Euro came in with a little more moisture in the eastern valley than 0z. Had to make a run to the Wally World for milk sandwiches for the snowpacalypse  so can’t post it. It has been consistently warmer in its precip outputs, but would be interested to see pivotal’s soundings 

[nrgjeff]

Interesting point about low level moisture Saturday. One huge challenge is not super moist above 700 mb. Dendrite growth temperature zone looks weak, but some moisture. Now if we were forecasting severe weather, I'm all about the extra ground moisture. Those concerns noted, It's a feisty little wave. Figure places with terrain help will be nice.

More notes added later: The Euro for Saturday appears a little low relative to consensus. Others have more qpf and snow, from more WAA aloft. Just a little more moisture up to 600 mb would be enough. GFS looks too amped, but I said that about the Euro for Friday. We'll see.

Moving to next week, the ECMWF and GFS remain in sharp disagreement. So do the weekly products. The issue is MJO forecasts. Unfortunately the (currently mild) Euro usually wins those battles. GFS has advantage in only 1-2 MJO phases, and these are not it.

That said, I'm in ski weenie mode after what just happened today and will happen tomorrow. Fingers crossed the GFS scores a rare win on the Euro next week. 

.

[John1122]

Just in the past 24 hours the NAM has expanded the precip shield NW and made it heavier. Yesterday at 18z the 24 hour snowfall was 50 percent of what it is now with virtually nothing reaching East Tennessee. 18z unfolding now has 1-3 from the Plateau eastward. 

[John1122]

Todays 18z NAM as the precip moves out overnight Sunday.

 

. 2

 

Yesterdays for the same 24 hour period.

 

The globals have been catching back onto these events later than the meso models and have had struggles with how far west/northwest the snowfall zones are. Middle and West Tennessee did much better yesterday than the globals suggested. The event in upstate SC/Western NC last week was almost happening before the Euro caught up. I think it was 12z the morning of the event before the Euro had the precip far enough NW for it to fall as frozen.

 

[Holston_River_Rambler]

MRX mentioning sun angle:

On Saturday, a h50 shortwave trough in cyclonic flow will move
through the Tennessee valley. Increasing dynamics aloft from PVA and
an 130 knot upper level jet to the south will allow for
precipitation to develop across Georgia and move north.
Temperature profiles favor this initial precipitation in the form
of snow, however, as warmer air moves north, most of this initial
snow is forecast to change over to a snow/rain mix and eventually
all rain by the afternoon. The forecast snow amounts are
uncertain across the southern valley while better confidence
exists across the higher terrain above 2500 feet. Here snow
amounts could range from 1 to 2 inches with locally higher
amounts of 3+ inches above 4000 feet.

Again as mentioned previously, much lower confidence exists
across the southern valley regarding snow totals. While initial
precipitation will be in the form of snow, it is expected that
this will change over to rain as warmer air moves north. It is
also expected that the snow will have a difficult time
accumulating because of the warmer surface temperatures and higher
sun angle. Because of the low confidence, felt it best to only
issue a special weather statement for Saturday and mention snow
showers for the valley of eastern Tennessee. As of this
afternoon, total snowfall ranges around a dusting to less than a
half inch of snow across the central and southern valley. Later
shifts will monitor and may issue an advisory if confidence
increases for heavier accumulations. The winter weather advisory
for the mountain zones of TN and NC will go into effect at 12Z
Saturday and will run through 00Z Sunday.

 

Bolding from me. 

[ShawnEastTN]

I have a sneaking suspicion we'll see WWAs posted for at least the southern great valley if not southern and central great valley during the overnight. Peachtree City just issued for all of North Georgia including Atlanta.

 

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[John1122]

Any met who mentions sun angle in early February regarding snow potential needs to reexamine climatology for February regarding snowfall in East Tennessee. 

[PowellVolz]

MRX mentioning sun angle:

On Saturday, a h50 shortwave trough in cyclonic flow will movethrough the Tennessee valley. Increasing dynamics aloft from PVA andan 130 knot upper level jet to the south will allow forprecipitation to develop across Georgia and move north.Temperature profiles favor this initial precipitation in the formof snow, however, as warmer air moves north, most of this initialsnow is forecast to change over to a snow/rain mix and eventuallyall rain by the afternoon. The forecast snow amounts areuncertain across the southern valley while better confidenceexists across the higher terrain above 2500 feet. Here snowamounts could range from 1 to 2 inches with locally higheramounts of 3+ inches above 4000 feet.Again as mentioned previously, much lower confidence existsacross the southern valley regarding snow totals. While initialprecipitation will be in the form of snow, it is expected thatthis will change over to rain as warmer air moves north. It isalso expected that the snow will have a difficult timeaccumulating because of the warmer surface temperatures and highersun angle. Because of the low confidence, felt it best to onlyissue a special weather statement for Saturday and mention snowshowers for the valley of eastern Tennessee. As of thisafternoon, total snowfall ranges around a dusting to less than ahalf inch of snow across the central and southern valley. Latershifts will monitor and may issue an advisory if confidenceincreases for heavier accumulations. The winter weather advisoryfor the mountain zones of TN and NC will go into effect at 12ZSaturday and will run through 00Z Sunday.

 
Bolding from me. 

Sun angel at the first of February?


.

[TellicoWx]

Honestly that whole Discussion was laughable at best...lol

[Holston_River_Rambler]

Maybe they meant time of day?