January Pattern and Storm Discussion

[tnweathernut]

Pattern has changed and we are still in late December. A LOT of winter (the heart of winter) ahead of us. Let's be glad we have started and look to continue to get rain.

We are entering a pattern (I have seen numerous times before) where the models will, at times, look silly beyond day 3. In fact, it wouldn't surprise me to see a nice wintry event that is missed almost right up to the event. With so much in the flow, models will struggle beyond day 3. You don't have to trust me, but I do have underwear older than some of you.

[GaWx]

The 12/26 12Z Euro run is pretty significant in that it is only the 2nd one of the last 8 to give any of N GA sig. wintry precip. during 1/1-3. It gives NW GA from near Cartersville/Rome over through most of the N ATL burbs 1-2.5" of snow during the AM of 1/3 with the heaviest from Rome westward to the AL border. The N ATL burbs get ~1-2". To that area's west, NE AL gets similar amounts. In addition, this run flirts with giving part of NE GA very light ZR (~0.10") during the AM of 1/4 from a second batch of precip. due to some CAD then. It is the FIRST Euro run giving N GA wintry precip. during 1/1-3 from a Miller A. The only other Euro run giving N GA wintry precip. of note was the 0Z 12/23 run, which gave N GA ~1" of snow from a clipper in NW flow/quite cold air.

Just from this Euro run alone since it is the "king" of models (despite not doing all that well in Dec.) and since this is just the 2nd Euro run showing something of sig., I'm raising the chance for a sig. wintry event for N GA 1/1-3 from 10% back up to 15% and the chance for a minor event from 10% back up to 15%. So, I'm back to thinking there is about a 1 in 3 shot of at least something minor vs. a 1 in 5 shot prior to this Euro run's release.

[Wow]

The 12/26 12Z Euro run is pretty significant in that it is only the 2nd one of the last 8 to give any of N GA sig. wintry precip. during 1/1-3. It gives NW GA from near Cartersville/Rome over through most of the N ATL burbs 1-2.5" of snow during the AM of 1/3 with the heaviest from Rome westward to the AL border. The N ATL burbs get ~1-2". To that area's west, NE AL gets similar amounts. In addition, this run flirts with giving part of NE GA very light ZR (~0.10") during the AM of 1/4 from a second batch of precip. due to some CAD then. It is the FIRST Euro run giving N GA wintry precip. during 1/1-3 from a Miller A. The only other Euro run giving N GA wintry precip. of note was the 0Z 12/23 run, which gave N GA ~1" of snow from a clipper in NW flow/quite cold air.

Just from this Euro run alone since it is the "king" of models (despite not doing all that well in Dec.) and since this is just the 2nd Euro run showing something of sig., I'm raising the chance for a sig. wintry event for N GA 1/1-3 from 10% back up to 15% and the chance for a minor event from 10% back up to 15%. So, I'm back to thinking there is about a 1 in 3 shot of at least something minor vs. a 1 in 5 shot prior to this Euro run's release.

I see nearly nothing significant in regards to precip of any kind on the 12z Euro run verbatim. The low dies out in the GOM and whatever precip there is falls into abv freezing air at the sfc as the weak HP slides off shore.

I give this solution about a 1 in 1000000000 chance of verifying anything close like this. Doesn't mean it won't snow/sleet/IP in N GA, but this solution verbatim is wrongo.

[WXinCanton]

I see nearly nothing significant in regards to precip of any kind on the 12z Euro run verbatim. The low dies out in the GOM and whatever precip there is falls into abv freezing air at the sfc as the weak HP slides off shore.

I tend to agree, Temps look awfully suspect for North GA verbatim. IMO, maybe some front end flurries then light rain/drizzle. Maybe mixed with a couple flakes.

[GaWx]

I see nearly nothing significant in regards to precip of any kind on the 12z Euro run verbatim. The low dies out in the GOM and whatever precip there is falls into abv freezing air at the sfc as the weak HP slides off shore.

I give this solution about a 1 in 1000000000 chance of verifying anything close like this. Doesn't mean it won't snow/sleet/IP in N GA, but this solution verbatim is wrongo.

Verbatim, the 12Z Euro gives up to 2.5" of snow to parts of NW GA per the actual model output maps I received. I didn't just make that up. The 2.5" snow area near the AL/GA border is produced by 0.35" of liquid equiv., verbatim, with air at 0C at 850 mb, verbatim. Your use of the word "verbatim" is incorrect and should be replaced by the word "interpretation". What I'm telling you is the model output "verbatim" per my provider. You're giving me your interpretation.

[Wow]

Verbatim, the 12Z Euro gives up to 2.5" of snow to parts of NW GA per the actual model output maps I received. I didn't just make that up. The 2.5" snow area near the AL/GA border is produced by 0.35" of liquid equiv., verbatim, with air at 0C at 850 mb, verbatim. Your use of the word "verbatim" is incorrect and should be replaced by the word "interpretation". What I'm telling you is the model output "verbatim" per my provider. You're giving me your interpretation.

Ok, you must be looking at the 192 hr precip map with the string of precip moving ahead of the low along the weak frontal boundary and nudges the 850mb line just into NW GA before moving out on the next panel. Yeah we definitely need to bump up the odds.

[GaWx]

Ok, you must be looking at the 192 hr precip map with the string of precip moving ahead of the low along the weak frontal boundary and nudges the 850mb line just into NW GA before moving out on the next panel. Yeah we definitely need to bump up the odds.

Yep, the Euro now showing a Miller A vs. not showing it on the prior runs is of significance. This is a good trend if it holds in future runs. Getting more interesting!

[WXinCanton]

Anyone seen the Euro ensembles yet? I'm mobile

[Wow]

Yep, the Euro now showing a Miller A vs. not showing it on the prior runs is of significance. This is a good trend if it holds in future runs. Getting more interesting!

I wish it were that black and white!

[Wow]

Anyone seen the Euro ensembles yet? I'm mobile

Sim to OP run thru 144.. weaker w/ the Baja low but that is due to varying locations between the ensemble members... but the OP run is on the western end of that spectrum as heights are lower thru TX.

[MillerA]

end of gsp disco

By Monday night...the situation changes as the broad upper ridge

axis should slide off the East Coast...and the flow aloft

strengthens from the SW. Moisture riding up the back side of the

ridge will increase from the top down late Monday night as

isentropic lift improves. Although the timing is difficult...it

seems plausible that a leading short wave will move through by

Tuesday morning. Thus...the GFS depiction of light precipitation breaking

out across the forecast area by sunrise appears reasonable. Min temperatures

should be above freezing in most places because of increasing cloud

cover early in the evening and warm advection toward daybreak. That

should preclude a p-type issue outside the higher terrain. A

consideration of thermal profiles from the GFS suggests that precipitation

may begin with a mixture over the higher terrain...but should be

mostly rain in the valleys outside the northern mountains the higher

elevations...including the northern mountains...may start as a period of sleet

changing to rain...or freezing rain where cold air is trapped. The

precipitation should transition to rain by middle morning. At this time...

amounts are expected to be light so the potential event looks

insignificant for the most part.

After the initial wave moves through...we remain under a moist SW

flow aloft with the potential for more isentropic lift and weak wave

passage. So...the chance pop was maintained through Tuesday and

Tuesday night until a stronger but sheared short wave moves through

Wednesday morning. Profiles suggest this will be more of a rain v

snow situation because we lack a prominent warm nose...so that is

the way we have played it. Precipitation amounts again look light...so in

spite of the chance snow forecast around daybreak Wednesday in the I-40

corridor...this does not look like something to get overly excited

about just yet. Temperatures will remain below normal.

[GaWx]

Anyone seen the Euro ensembles yet? I'm mobile

Yes, in concert with the improved 12Z Euro op. run, the 12Z Euro ens. mean definitely looks better than the 0Z. For our area in particular around the time the 12Z Euro op. gave us snow (the period 0Z to 18Z on 1/3):

-0Z Euro ens. mean gave only ~1/8" of QPF

-12Z Euro ens. mean gives ~1/4" of QPF...so, about doubled..and the 0C 850 line is still near the northern ATL burbs. So, a good bit wetter mean without it being warmer. Hard to not like this.

Edit: I think that the increased precip. is helping to lower the 850 temp.'s more from where they'd otherwise be via additional evap. cooling at 5K feet.

[SN_Lover]

ugh temp just need to go down 4 more C then we might be in business.

12z sat for charlotte.

.92in of precipitable water, warm advection noted.

[GaWx]

ugh temp just need to go down 4 more C then we might be in business.

12z sat for charlotte.

.92in of precipitable water, warm advection noted.

Which Saturday? This one or the following one.

[SN_Lover]

Which Saturday? This one or the following one.

the one coming up(29th).

[GaWx]

the one coming up(29th).

Would you mind moving this to another thread? This is the January thread and it is confusing. We're not talking about that system here. We're talking about the subsequent one. Thanks in advance.

[SN_Lover]

Would you mind moving this to another thread? This is the January thread and it is confusing. We're not talking about that system here. We're talking about the subsequent one. Thanks in advance.

if a mod can move it that would be great.

[Snow86]

Yep, the Euro now showing a Miller A vs. not showing it on the prior runs is of significance. This is a good trend if it holds in future runs. Getting more interesting!

I hope you're kidding. I don't care what some garbage snowfall map shows - the weather doesn't conform to a models interpretation of snowfall. Look at the synoptic pattern - there's no cold air! That stagnant cold air is not going to get the job done.

[packbacker]

18z is close to a whopper, it's a little disorganized but still lots of potential.

[Snow86]

Yes, in concert with the improved 12Z Euro op. run, the 12Z Euro ens. mean definitely looks better than the 0Z. For our area in particular around the time the 12Z Euro op. gave us snow (the period 0Z to 18Z on 1/3):

-0Z Euro ens. mean gave only ~1/8" of QPF

-12Z Euro ens. mean gives ~1/4" of QPF...so, about doubled..and the 0C 850 line is still near the northern ATL burbs. So, a good bit wetter mean without it being warmer. Hard to not like this.

Edit: I think that the increased precip. is helping to lower the 850 temp.'s more from where they'd otherwise be via additional evap. cooling at 5K feet.

You do realize snow has to fall through air below freezing all the way to the ground right? Do you have a clever statistic for how many times the 850mb temperature has been 0C and the precipitation is still rain? I can guarantee you it happens quite a bit.

[CAD_Wedge_NC]

You do realize snow has to fall through air below freezing all the way to the ground right? Do you have a clever statistic for how many times the 850mb temperature has been 0C and the precipitation is still rain? I can guarantee you it happens quite a bit.

I have seen light rain for several hours with 850's at -3C due to a warm layer from 900mb to the surface. However it doesn't happen like that often. Usually the warm nose is around 750mb-800mb.

[Snow86]

I have seen light rain for several hours with 850's at -3C due to a warm layer from 900mb to the surface. However it doesn't happen like that often. Usually the warm nose is around 750mb-800mb.

Same difference. Looking at 850mb temperatures is not that useful in determining precipitation type. So many on this board seem to take it for granted that if 850 is below freezing the precipitation type is automatically snow.

[franklin NCwx]

Same difference. Looking at 850mb temperatures is not that useful in determining precipitation type. So many on this board seem to take it for granted that if 850 is below freezing the precipitation type is automatically snow.

it is if you live in the mtns.

[Cold Rain]

Same difference. Looking at 850mb temperatures is not that useful in determining precipitation type. So many on this board seem to take it for granted that if 850 is below freezing the precipitation type is automatically snow.

If 850 is above 0C then you probably won't get snow, so in that aspect, it's useful to know what they are.

[Snow86]

If 850 is above 0C then you probably won't get snow, so in that aspect, it's useful to know what they are.

So is 849, 848, 847 too. Of course that's what partial thicknesses are for...

[packbacker]

on phone at doctors office elaborate more. Thanks

Classic miller A day 7/8...The phase wasn't very clean and thus why it's not stronger, IMO.

[Cold Rain]

So is 849, 848, 847 too. Of course that's what partial thicknesses are for...

But for a Miller A 8 or 9 days away, the 850 0 line is a decent approximation. We can worry about thicknesses later.

[SN_Lover]

Same difference. Looking at 850mb temperatures is not that useful in determining precipitation type. So many on this board seem to take it for granted that if 850 is below freezing the precipitation type is automatically snow.

While your assertion of right most of the time, you could get the melting effect and if the warm layer is below .5C you could still receive snow. i think most on here acknowledge that the 850 0C line is not the only indicator of snow.

[Snow86]

But for a Miller A 8 or 9 days away, the 850 0 line is a decent approximation. We can worry about thicknesses later.

I really could not disagree more. I often see on here something along these lines: "Discount the surface temperature forecast, it's not accurate 9-10 days out." 850mb is also a surface - a pressure surface at one level just like the surface temperature is. Partial thicknesses looks at the layer average, sort of like an ensemble if you will.

[SN_Lover]

I really could not disagree more. I often see on here something along these lines: "Discount the surface temperature forecast, it's not accurate 9-10 days out." 850mb is also a surface - a pressure surface at one level just like the surface temperature is. Partial thicknesses looks at the layer average, sort of like an ensemble if you will.

are you really relying on model temp forecasts THAT far ahead? just curious, did you know that model verification scores are plummeting for projections 5+days out? Again, the synoptic pattern should only be noted now.