The Return of the 12/5 Snowstorm

[wxdude64]

5 hours ago, wxdude64 said:

NWS has WWA for 2-4 here, we shall see. Funny that the 'high end' keeps going up, yesterday at this time my location had a 30% chance at 4" and a 5% chance of 6". As of the last update I'm now at 55% chance of 4", 30% chance of 6" and 5% chance at 8". Think that may be high unless we get 15 to 18-1 ratios. I'll be thrilled with the 2-4 in forecast verifying.  

Bumped up again, now 65% chance at 4", a 38% chance at 6" and a 10% chance at 8".  NWS bumped forecast to 3-6 total. 

[midatlanticweather]

Any chance for high ratios?

LOL! Get every bit out of it we can squeeze! 

 

[WEATHER53]

5 minutes ago, ravensrule said:

He got banned over some nonsense in that moronic OT thread. So ludicrous. Supposed adults acting like children. 

Randall my good man. Please get him back. OT should not get him kicked from here-just OT only 

Matthew Baratta Niktu 

[Solution Man]

2 minutes ago, wxdude64 said:

Bumped up again, now 65% chance at 4", a 38% chance at 6" and a 10% chance at 8".  NWS bumped forecast to 3-6 total. 

Should be WInter Storm Warming stuff

[yoda]

18z 3km NAM total QPF

[SnowenOutThere]

Alright let's do this one last time. One final real analysis post before it becomes nowcasting time. Firstly, lets go over the whole progression that got us to this point. Feel free to skip past this part if you just want updates! 5 days ago I made my first post where I lamented over the low out west getting stuck leading to thermal issues over us. It's important to note that initially we were relying on the shortwave after our current storm to induce cyclogenesis. I will give myself some credit as I correctly identified we needed to get our low out of the Southwest ASAP (though admittedly, I was still thinking of the second shortwave). 

By Monday the guidance was split over if wave 1 or wave 2 would be the trigger for the storm. Last Monday's 12z Euro this quite well as it had our wave get shredded to pieces before wave 2 tried to help out. 

Notice how this is for Saturday 0z, hence why this storm was initially progged as a Friday-Saturday storm. At this juncture it was pretty clear we had to get wave 1 to be dominant over wave 2 (or run out ahead of it) to get a storm. 

Luckily, over the next few days that is exactly what happened. We got the double positive of wave 1 speeding up and the mess of energy entering the west slowing down. Another thing we needed (identified Tuesday) was to have the incoming velocity be both more negatively tilted and further south (as it would encourage our wave to gain latitude). The difference between the 18z Nam 12k on Tuesday and its 12z run today shows just how positively almost everything trended!

We have a further east wave 1, generally slower wave 2, more N/S orientation of wave 2, and more energy displaced south for wave 2! Look at how our shortwave responds by actually gaining a tilt instead of flattening out! Tracking the evolution of this storm has been a reward by itself as it really shows just how many things we need to go right to get snow. Of course, the real reward is the snow itself. 

So with the history out of the way what is left to forecast? 

Well, at this point the synoptics are in place and we have our last real useful runs before this fully transitions to nowcasting. That said, lets draw some attention to the start of this event. Another piece that has trended better overtime is how quickly we can fully saturate the column with moisture (namely as a stronger storm means better wind direction and speed to advect moisture into our area), as the initial atmosphere is extremely dry (see sounding at 7pm tonight)

Luckily as mentioned above we have strong winds from around 850mb up to bring in moisture from the Gulf!

However, this alone would not really get us anywhere. This is where the real exciting part of this post comes in! 700mb temp advection and frontogenesis! I'll be honest this part is extremely exciting to me. Take this Nam snapshot at 1am tonight of temperature advection in the 700mb layer.

Look at that strong temp advection in the 700mb layer! That's how you bring in moist air! As a note, this is better than its 12z run hence the improvement in snowfall totals. What this then means is this storm looks to come in hot and heavy with a good thump of snow via 700mb frontogenesis (once the column fully saturates ofc). This is shown with the NAM sounding at 1am as you can really see the lift this provides for 850mb up past 500mb (which includes the DGZ btw)!

One other thing I want to note is a maximum that shows up with 850mb forcing right over the NOVA area at 9z on the Nam (and to a less extent the HRRR)

I do wonder if this holds true that someone in that zone could have a mini jackpot. (A counterpoint to that is that the DGZ is still above 600mb but honestly I don't know how that interacts with lift in the 850mb layer). From here on out I'll be looking at the NWS analysis page to see where the best frontgen ends up occurring! 

It has truly been a joy tracking this event with all of you. Being honest, University wasn't all it was cracked up to be (in some regards I still like it overall!) so your kind words were appreciated. I also want to thank everyone who's posted meteorology analysis before as those contributions are what got me to make this thread (even if years removed from the advice given). My advice for any poster who wants to learn analysis is just look at the 500mb maps and try to figure out the connections of vorticity for what makes a "good" and "bad" run as that should get you started thinking more upper-air based. Thank you all again (especially @Terpeast @WxUSAF @psuhoffman @CAPE @Eskimo Joe and the posters I'm forgetting from this list (sorry!)) for helping. Hope for snow.

[adelphi_sky]

I myself would be happy to see my children go berserk over snow TV this early in the season. Win/Win. I just hope it doesn't end until evening. 

[katabatic]

7 minutes ago, wxdude64 said:

Bumped up again, now 65% chance at 4", a 38% chance at 6" and a 10% chance at 8".  NWS bumped forecast to 3-6 total. 

You're in a good spot - I seriously hope you overperform. My Dad (Midlothian outside of Richmond) is too. I doubt I'll see much more than conversation flakes, but boy it's been cold here. Parts of Broadford Lake (poor man's Deep Creek near my house) are starting to ice over even. Hi of 26 yesterday and currently sitting at 23 with a thick overcast. 

[SnowenOutThere]

1 minute ago, SnowenOutThere said:

Alright let's do this one last time. One final real analysis post before it becomes nowcasting time. Firstly, lets go over the whole progression that got us to this point. Feel free to skip past this part if you just want updates! 5 days ago I made my first post where I lamented over the low out west getting stuck leading to thermal issues over us. It's important to note that initially we were relying on the shortwave after our current storm to induce cyclogenesis. I will give myself some credit as I correctly identified we needed to get our low out of the Southwest ASAP (though admittedly, I was still thinking of the second shortwave). 

By Monday the guidance was split over if wave 1 or wave 2 would be the trigger for the storm. Last Monday's 12z Euro this quite well as it had our wave get shredded to pieces before wave 2 tried to help out. 

Notice how this is for Saturday 0z, hence why this storm was initially progged as a Friday-Saturday storm. At this juncture it was pretty clear we had to get wave 1 to be dominant over wave 2 (or run out ahead of it) to get a storm. 

Luckily, over the next few days that is exactly what happened. We got the double positive of wave 1 speeding up and the mess of energy entering the west slowing down. Another thing we needed (identified Tuesday) was to have the incoming velocity be both more negatively tilted and further south (as it would encourage our wave to gain latitude). The difference between the 18z Nam 12k on Tuesday and its 12z run today shows just how positively almost everything trended!

We have a further east wave 1, generally slower wave 2, more N/S orientation of wave 2, and more energy displaced south for wave 2! Look at how our shortwave responds by actually gaining a tilt instead of flattening out! Tracking the evolution of this storm has been a reward by itself as it really shows just how many things we need to go right to get snow. Of course, the real reward is the snow itself. 

So with the history out of the way what is left to forecast? 

Well, at this point the synoptics are in place and we have our last real useful runs before this fully transitions to nowcasting. That said, lets draw some attention to the start of this event. Another piece that has trended better overtime is how quickly we can fully saturate the column with moisture (namely as a stronger storm means better wind direction and speed to advect moisture into our area), as the initial atmosphere is extremely dry (see sounding at 7pm tonight)

Luckily as mentioned above we have strong winds from around 850mb up to bring in moisture from the Gulf!

However, this alone would not really get us anywhere. This is where the real exciting part of this post comes in! 700mb temp advection and frontogenesis! I'll be honest this part is extremely exciting to me. Take this Nam snapshot at 1am tonight of temperature advection in the 700mb layer.

Look at that strong temp advection in the 700mb layer! That's how you bring in moist air! As a note, this is better than its 12z run hence the improvement in snowfall totals. What this then means is this storm looks to come in hot and heavy with a good thump of snow via 700mb frontogenesis (once the column fully saturates ofc). This is shown with the NAM sounding at 1am as you can really see the lift this provides for 850mb up past 500mb (which includes the DGZ btw)!

One other thing I want to note is a maximum that shows up with 850mb forcing right over the NOVA area at 9z on the Nam (and to a less extent the HRRR)

I do wonder if this holds true that someone in that zone could have a mini jackpot. (A counterpoint to that is that the DGZ is still above 600mb but honestly I don't know how that interacts with lift in the 850mb layer). From here on out I'll be looking at the NWS analysis page to see where the best frontgen ends up occurring! 

It has truly been a joy tracking this event with all of you. Being honest, University wasn't all it was cracked up to be (in some regards I still like it overall!) so your kind words were appreciated. I also want to thank everyone who's posted meteorology analysis before as those contributions are what got me to make this thread (even if years removed from the advice given). My advice for any poster who wants to learn analysis is just look at the 500mb maps and try to figure out the connections of vorticity for what makes a "good" and "bad" run as that should get you started thinking more upper-air based. Thank you all again (especially @Terpeast @WxUSAF @psuhoffman @CAPE @Eskimo Joe and the posters I'm forgetting from this list (sorry!)) for helping. Hope for snow.

For posterity heres all of that condensed into a snowfall map for my friends (sorry MD crew). 

[MillvilleWx]

3 hours ago, Terpeast said:

My baby son is due tomorrow morning, so it may very well be that we'll be driving through the snow on slippery roads to get to the hospital. It won't take much snow to make the roads dicey especially with cold temperatures overnight. Fortunately it's only a 10 minute drive and we'll give ourselves extra time to get there. 

Will probably be busy over the next couple of weeks, but I'll try to pop in here if there's something else to track.

May it snow tomorrow and everyone gets at least 1"!

Congratulations!! The birth of a future weather weenie  

[WEATHER53]

1 minute ago, MillvilleWx said:

Congratulations!! The birth of a future weather weenie  

If it really maxes out then could he be named Fifth or Finch?

[WxWatcher007]

Good luck tomorrow, everyone.

[snowmagnet]

13 minutes ago, SnowenOutThere said:

Alright let's do this one last time. One final real analysis post before it becomes nowcasting time. Firstly, lets go over the whole progression that got us to this point. Feel free to skip past this part if you just want updates! 5 days ago I made my first post where I lamented over the low out west getting stuck leading to thermal issues over us. It's important to note that initially we were relying on the shortwave after our current storm to induce cyclogenesis. I will give myself some credit as I correctly identified we needed to get our low out of the Southwest ASAP (though admittedly, I was still thinking of the second shortwave). 

By Monday the guidance was split over if wave 1 or wave 2 would be the trigger for the storm. Last Monday's 12z Euro this quite well as it had our wave get shredded to pieces before wave 2 tried to help out. 

Notice how this is for Saturday 0z, hence why this storm was initially progged as a Friday-Saturday storm. At this juncture it was pretty clear we had to get wave 1 to be dominant over wave 2 (or run out ahead of it) to get a storm. 

Luckily, over the next few days that is exactly what happened. We got the double positive of wave 1 speeding up and the mess of energy entering the west slowing down. Another thing we needed (identified Tuesday) was to have the incoming velocity be both more negatively tilted and further south (as it would encourage our wave to gain latitude). The difference between the 18z Nam 12k on Tuesday and its 12z run today shows just how positively almost everything trended!

We have a further east wave 1, generally slower wave 2, more N/S orientation of wave 2, and more energy displaced south for wave 2! Look at how our shortwave responds by actually gaining a tilt instead of flattening out! Tracking the evolution of this storm has been a reward by itself as it really shows just how many things we need to go right to get snow. Of course, the real reward is the snow itself. 

So with the history out of the way what is left to forecast? 

Well, at this point the synoptics are in place and we have our last real useful runs before this fully transitions to nowcasting. That said, lets draw some attention to the start of this event. Another piece that has trended better overtime is how quickly we can fully saturate the column with moisture (namely as a stronger storm means better wind direction and speed to advect moisture into our area), as the initial atmosphere is extremely dry (see sounding at 7pm tonight)

Luckily as mentioned above we have strong winds from around 850mb up to bring in moisture from the Gulf!

However, this alone would not really get us anywhere. This is where the real exciting part of this post comes in! 700mb temp advection and frontogenesis! I'll be honest this part is extremely exciting to me. Take this Nam snapshot at 1am tonight of temperature advection in the 700mb layer.

Look at that strong temp advection in the 700mb layer! That's how you bring in moist air! As a note, this is better than its 12z run hence the improvement in snowfall totals. What this then means is this storm looks to come in hot and heavy with a good thump of snow via 700mb frontogenesis (once the column fully saturates ofc). This is shown with the NAM sounding at 1am as you can really see the lift this provides for 850mb up past 500mb (which includes the DGZ btw)!

One other thing I want to note is a maximum that shows up with 850mb forcing right over the NOVA area at 9z on the Nam (and to a less extent the HRRR)

I do wonder if this holds true that someone in that zone could have a mini jackpot. (A counterpoint to that is that the DGZ is still above 600mb but honestly I don't know how that interacts with lift in the 850mb layer). From here on out I'll be looking at the NWS analysis page to see where the best frontgen ends up occurring! 

It has truly been a joy tracking this event with all of you. Being honest, University wasn't all it was cracked up to be (in some regards I still like it overall!) so your kind words were appreciated. I also want to thank everyone who's posted meteorology analysis before as those contributions are what got me to make this thread (even if years removed from the advice given). My advice for any poster who wants to learn analysis is just look at the 500mb maps and try to figure out the connections of vorticity for what makes a "good" and "bad" run as that should get you started thinking more upper-air based. Thank you all again (especially @Terpeast @WxUSAF @psuhoffman @CAPE @Eskimo Joe and the posters I'm forgetting from this list (sorry!)) for helping. Hope for snow.

You had me at frontogenesis. We don’t get enough of it around here. Also hot and heavy has been a rare sight over the last decade.

[Jebman]

3 hours ago, Terpeast said:

My baby son is due tomorrow morning, so it may very well be that we'll be driving through the snow on slippery roads to get to the hospital. It won't take much snow to make the roads dicey especially with cold temperatures overnight. Fortunately it's only a 10 minute drive and we'll give ourselves extra time to get there. 

Will probably be busy over the next couple of weeks, but I'll try to pop in here if there's something else to track.

May it snow tomorrow and everyone gets at least 1"!

Congrats! The stoke is high over the arrival of our latest snow weenie!

[Ji]

He got banned over some nonsense in that moronic OT thread. So ludicrous. Supposed adults acting like children. 

What? Zwyts got banned? He is a legend. Bring him back

[Ji]

Congrats terpeast. My daughters were born on 12/7 and 12/8 lol

[ravensrule]

2 minutes ago, snowmagnet said:

Also hot and heavy has been a rare sight over the last decade.

You have obviously been going to the wrong clubs. 

[ravensrule]

Just now, Ji said:

What? Zwyts got banned? He is a legend. Bring him back

Sad but true. Agreed 1,000%.

[Jebman]

1 minute ago, Ji said:

What? Zwyts got banned? He is a legend. Bring him back

Free zwyts at once! He goes waaaaaay back!

[winter_warlock]

10 minutes ago, WEATHER53 said:

If it really maxes out then could he be named Fifth or Finch?

Named? Lol for a 2 to 4 inch storm?  Lol

[WEATHER53]

The slant and movement of the largest and heaviest area of precip  down around Memphis is ene 

[WEATHER53]

12 minutes ago, Ji said:

What? Zwyts got banned? He is a legend. Bring him back

He was getting a lot of crap about “Jews Bad” so he lashed out 

[bncho]

Surprised nobody’s mentioning that DC and points south finally have a chance to reach December climo after several years! Pretty exciting!

[Eskimo Joe]

2 minutes ago, bncho said:

Surprised nobody’s mentioning that DC and points south finally have a chance to reach December climo after several years! Pretty exciting!

Yes indeed!

[yoda]

Just about nowcasting time, but IMO, 18z ICON looks better in that its a bit more smoothed out with its 1 inch marker delineation on the 18z run compared to the 12z run

[SnowenOutThere]

21 minutes ago, snowmagnet said:

You had me at frontogenesis. We don’t get enough of it around here. Also hot and heavy has been a rare sight over the last decade.

Should mention "hot and heavy" is still in the context of this storm's version of it. Though it will definitely be pretty as it falls. 

[George BM]

1 hour ago, BlizzardNole said:

Parts of the area also got snow on 12/5/2003.  That was back when N&W suburbs meant something.  I had like 8" in Germantown and rode the MARC to DC for work and it was wet ground there

Ha. That's right. Temporarily forgot about that one. Five times in the 00s. Wild indeed. 

Looking forward to adding to this tally tomorrow.

[BlizzardNole]

41 minutes ago, SnowenOutThere said:

For posterity heres all of that condensed into a snowfall map for my friends (sorry MD crew). 

Nice map!  Virginia living right:  UVA in ACC championship and chance for playoffs, VT has shiny new coach, and SNOW

[bncho]

I’m incautiously confident that DC will get 1-3”, and somewhere within a 25 mile radius of DC will get 4”.

[Cobalt]

1.6" at DCA would be the snowiest December event for the airport in 16 years. Guidance says to take the under but certainly not off the table.