December 2017 Observations and Discussions

[Craig-OmahaWX]

Holy crap snowing for a day and a half and no end in sight. If that happens I'll sit outside in a lawn chair drinking a DQ blizzard lol. 

[bud2380]

Cue the GFS clown maps. Gonna be another crazy one.

[Andrew NE]

Haha. That thing is a monster.

[hlcater]

From AmWx.

 

[Jaycee]

Holy hell, the low starts forming in Vegas, and literally drops snow across the plains all the way out there, and then only continues to wind up. Clown maps are gunna be ridiculous out here.

[NH4NU]

Showing 18" for Omaha at 216hr haha 

 

and 30" up around Yankton

[bud2380]

Gfs has a foot plus for almost all of Iowa, Nebraska, and Wisconsin

[Craig-OmahaWX]

LOL

 

http://maps1.pivotalweather.com/maps/models/gfs/2017122100/228/snku_acc.us_c.png

[james1976]

We deserve this after such a lame December. Come on and deliver this, Snow Gods!

[Minny_Weather]

Yeah oops. Spoke too soon. That'd actually be a perfect scenario. The later it trends, the less likely it is that I have to fly home in that and I'll still get to experience it.

[WBadgersW]

Add on some lehs to that... So much eye candy.

[snowstorm83]

Well good luck guys, if this materializes you better still have it on the ground when I get back the 6th lol!

[Money]

http://www.pivotalweather.com/model.php?m=gfs&p=sfct&rh=2017122100&fh=288&r=us_mw&dpdt=

 

Gfs has HIGH temps of -30 in MN after the storm

[gabel23]

If we would get half that it would be nuts. That's enough snow to stop most of the bitching on this site. You build a glacier that fast it's a matter of time before our friends along and south of I-70 share in our fun. If even a little of this magic happens I'm happy; lets just hope the other models start smoking what the GFS is burning.......

[Minny_Weather]

The GFS is obviously bullish on everything, we're not gonna get over a foot in Lincoln, but I'm still liking the potential. The more bullish everything is, the more likely we are to get appreciable snow and cold in the end.

[gabel23]

http://www.pivotalweather.com/model.php?m=gfs&p=sfct&rh=2017122100&fh=288&r=us_mw&dpdt=

 

Gfs has HIGH temps of -30 in MN after the storm

Highs in the teen's below zero would rival December of 1983 around these parts. If the GFS is right with the amount of snow it spat out tonight I would believe that temp profile! 

[bud2380]

The 10:1 map has a much more realistic look to it

[gabel23]

http://www.pivotalweather.com/model.php?m=gfs&p=sfct&rh=2017122100&fh=288&r=us_mw&dpdt=

 

Gfs has HIGH temps of -30 in MN after the storm

By the way these low temps would be absurd for my state this time of year! 

[gabel23]

The 10:1 map has a much more realistic look to it

Agree, and I would take even half that!! 

[Minny_Weather]

If we get any sort of WSW snow out of this I'll be happy. It's been too long since Lincoln has had WSW level snows.

[gabel23]

So one model says a bowling ball and another says southern storm up to the east coast. I just hope the king EURO shows something, give us hope. 

[Snowlover76]

While the recent trends are nice I ain't getting excited until Monday.

[Minny_Weather]

Yeah I'm wondering what the Euro will do with the 00z data. If the Euro continues the "what storm" trend, that'll have to be the biggest model disagreement in history and will definitely have WFOs in panic mode as it's already 7 days out.

[Minny_Weather]

While the recent trends are nice I ain't getting excited until Monday.

I actually agree with you (?!). As this is a relatively new storm system, it's best to wait a couple days and see more model runs before we celebrate. Otherwise you'll just have an aneurysm when everything trends downward. If we still see this Friday, then I'll know this is legit.

[Hawkeye]

A few days ago the GFS had high temps here on Xmas near zero.  Now it has us in the 20s, with nothing lower than 20s through day nine.

[Tabitha]

Snowing here in the  Black Hills for the last hour or so; with less than a 1/2 inch of new snow and a brisk north wind @ 11 PM MST. 

 

Visibility is still greater than one mile.  Temperature has fallen back to about 23 F.

[Tabitha]

Reporting the actual rate of snowfall; my understanding is that light snow is anything with a visibility greater than 1/2 mile; moderate snow is snow with a visibility from 1/4 to 1/2 mile...and heavy snow is anything where the visibility is under 1/4 of a mile.

[Craig-OmahaWX]

EURO is still radically different tonight lol. 

[Hawkeye]

GFS and Euro on different planets next week.  The euro keeps a flat wnw flow going all week.  Any waves are very weak and the gulf is closed for business.  The GFS is on its own tonight, which doesn't bode well.

 

The euro has the Sunday wave missing south now, too, so we could still make it to January without any measurable snowfall.

[Grizzcoat]

Reporting the actual rate of snowfall; my understanding is that light snow is anything with a visibility greater than 1/2 mile; moderate snow is snow with a visibility from 1/4 to 1/2 mile...and heavy snow is anything where the visibility is under 1/4 of a mile.

You are correct.

 

 charts taken from the 7900.5D from the FAA Surface Weather Observer Program table 10-5  and also from the FMH-1 (Federal Meteorological Handbook #1)- table 8-4

 

 

 

Light snow - visibility > then 1/2 mile

Moderate snow - visibility  > then 1/4 mile but less then or = to 1/2 mile

Heavy snow - visibility less then or = to 1/4 mile

 

of course an observer can have -SN with a vis at 1/2 mile or SN at a vis of 1/4 mile if the main form of preicp or an obscuration to the visibility is not the snow but something else such as FZFG/ FG  or DZ or PL or even BLSN or various combinations.

[Craig-OmahaWX]

All models have different outcomes...however, each outcome presented is an option that I have seen on one of the ensembles.

[Craig-OmahaWX]

However, the GFS ensembles is much better tonight in terms of a storm over the Plains.

[Tabitha]

Light snow - visibility > then 1/2 mile

Moderate snow - visibility  > then 1/4 mile but less then or = to 1/2 mile

Heavy snow - visibility less then or = to 1/4 mile

 

of course an observer can have -SN with a vis at 1/2 mile or SN at a vis of 1/4 mile if the main obscuration to the visibility is not the snow but something else such as FZFG/ FG  or DZ or PL or even BLSN or various combinations.

 

Yeah, I think that's more or less the way I put it.

 

The autumn was not good for snow here; with just 5.6" at this spot; but the winter is off to a good start as some light to moderate snow continues with a brisk N wind; temperature down to 22 F; some blowing snow @ 12:15 AM.

[Tabitha]

Yeah, I think that's more or less the way I put it.

 

The autumn was not good for snow here; with just 5.6" at this spot; but the winter is off to a good start as some light to moderate snow continues with a brisk N wind; temperature down to 22 F; some blowing snow @ 12:15 AM.

 

Each run of the HRRR edges a little further north with the snow; the RGEM was practically dry here until the last run at 0z...but looked not bad then.

 

Doesn't take much to squeeze out a nice snowfall here; as the worst ratios in a non-spring snow are never worse than 20:1...and since it is cold from top to bottom here; 25:1 seems about right.

[Tabitha]

As 7z GMT / 0z MST there was a 1000 mb Low trying to organize near Denver.  The wind is trying to veer to the NE here; which would help immeasurably as it would be forced up the eastern slopes of the Black Hills and wring out whatever there is.

 

Cold most certainly settling in as its down to just 11 F at one of the high stations just outside of Lead / elev. 6070'.

[Tabitha]

Much of the forecast snow across the Midwest appears to have evaporated on the midnight run of the Canadian; it was never really there on the European; save for the 12z run on Tuesday; though the GFS continues to feature it...GFS is somewhat erratic outside of 120 hours...sad, when you consider its the top rated US mid range model...so odds are it will cave to the Euro...but this has been a strange autumn; so you never know.

[Tabitha]

6z GFS holds serve; remaining interesting and wet over the next 240 hours...unusually wet back east where the hills of south central PA have over 55 inches of snow progged in spots; and that's not really a lake effect area; though they might get some residual stuff.

 

Dendrite growth looked a bit better here in the last few minutes as the temperature has fallen back to 16 F.

[Tom]

00z EPS looks starkly different than it's operational for next weeks storm potential.  Certainly has the look of the blocking Banana HP across the north and many members skirt across the S Plains/MW and then half the members want to cut the storm up the OV with a secondary low developing along the EC.  Nonetheless, the idea of a slow moving system is in the cards.  I firmly believe there will be a system to track so we just need to be a bit patient as we are still about 6-7 days out.  Interestingly, for the first time this season, we will have high lat blocking during the aforementioned period and a key west-based Greenland Block which provides room for amplification.  Gotta say, this pattern is really exciting going forward.  FWIW, the Canadian weeklies last week and the week before had the right idea for a coast-to-coast active pattern Christmas week.  #Nailedit

 

 

Regarding the cold, and the evolution of the step-down pattern of the cold coming around Christmas to finish off the month, I think the coldest departures of the season come post next weeks system into the first week of January.  Fit's the pattern and I always had my eye on the PV to come back sometime during the early part of the first week of January. Might even be around the New Year. Remember Nov 8-10th pattern where we had a brief PV intrusion across the GL's??  I think something similar happens but may be more intense due to the high lat blocking which seems to be locking now.

[St Paul Storm]

6z GFS holds serve; remaining interesting and wet over the next 240 hours...unusually wet back east where the hills of south central PA have over 55 inches of snow progged in spots; and that's not really a lake effect area; though they might get some residual stuff.

 

Dendrite growth looked a bit better here in the last few minutes as the temperature has fallen back to 16 F.

How much snow has fallen so far there? Radar returns look good.

[Tom]

BTW, at 10:28 CST we welcome the Winter Solstice!  Happy Winter!  Ironically, for much of this sub forum we have not seen much wintry weather and seemingly like clock work, nature decides to begin delivering some wintry wx today.  I think this period we are entering today and through the end of the month will certainly be remembered as the period for this season when winter really begins.  Delayed, but not denied (except for some MN/WI/MI peeps)!  All the players are finally coming together and I'm encouraged that most of us on here will see good opportunities for some appreciable snows.