December 2023

[Ginx snewx]

1 minute ago, WinterWolf said:

I’ll still take the way under here on winds…unless it’s a tropical system, 99% of the time its a snoozer here in that regard.  NAM would be interesting here with a couple inches of snow, but I’ll sell that too.   We’ll get 3 plus inches of rain, that’s what I’m pretty sure of though.  Congrats who gets the snow, and the wind out east. 

Tropical storm conditions for a couple hrs. 

[jbenedet]

3 minutes ago, weatherwiz said:

With the way things have been evolving (which I am certainly going to be wrong on with thinking the backend snow was overdone) there is probably a better chance of minor accumulations to the CT River in CT than there is strong winds (gusts 40-50+) within CT (outside of SE CT).

I’m actually thinking the opposite with this. 
 

Kinda like that one time out of 20 where the model guidance is not going to fail for its known biases.

[WinterWolf]

4 minutes ago, Ginx snewx said:

Tropical storm conditions for a couple hrs. 

I guess I should have said high end tropical storm winds, not 35 -40 mph, those are nothing.  Especially with no leaves.  If I’m wrong, I’ll gladly admit this was a surprise.  Hoping Kevin is right…all inflatable’s blown into Maine. 

[jbenedet]

The warmth today is a pretty big indication of the “wind” aspect of the storm potential tomorrow.

[WxWatcher007]

8 minutes ago, weatherwiz said:

With the way things have been evolving (which I am certainly going to be wrong on with thinking the backend snow was overdone) there is probably a better chance of minor accumulations to the CT River in CT than there is strong winds (gusts 40-50+) within CT (outside of SE CT).

Windy with warm rain to cold rain here IMO

[CoastalWx]

It’s approaching 50 and still snow cover just to my southeast. December sign for the win.

[weatherwiz]

Just now, jbenedet said:

I’m actually thinking the opposite with this. 
 

Kinda like that one time out of 20 where the model guidance is not going to fail for its known biases.

I am still a bit torn on the system as a whole. At least to me, when it comes to the backend snow aspect and how significant that is, alot is going to depend on whether one of these waves intensifies like guidance has been showing. The consistency has certainly been there, but we've seen similar situations before where inside 36 hours models back off. 

How far inland the strong wind potential is will be tied into where the lows track. If they're tracking say right up the CT River the best LLJ and strongest winds are going to be well off to the East. I think think for majority of inland the best winds are going to be with the CAA Monday. 

[40/70 Benchmark]

Hopefully DC grabs a few inches....I am anecdotally pulling this out of my rear, but I feel like a plowable December snowfall in DC would a good omen for the rest of winter.

[jbenedet]

3 minutes ago, weatherwiz said:

I am still a bit torn on the system as a whole. At least to me, when it comes to the backend snow aspect and how significant that is, alot is going to depend on whether one of these waves intensifies like guidance has been showing. The consistency has certainly been there, but we've seen similar situations before where inside 36 hours models back off. 

How far inland the strong wind potential is will be tied into where the lows track. If they're tracking say right up the CT River the best LLJ and strongest winds are going to be well off to the East. I think think for majority of inland the best winds are going to be with the CAA Monday. 

It’s safest to take the under on the snow accum side. 
 

You’ll have snow falling but storm racing north northeast while ground is warm and temps are in mid to up 30’s. The airmass behind it is seasonal at best. It’s the warmth and associated subtropical jet ahead of it that’s making for the fireworks.

[weatherwiz]

2 minutes ago, jbenedet said:

It’s safest to take the under on the snow accum side. 
 

You’ll have snow falling but storm racing north northeast while ground is warm and temps are in mid to up 30’s. The airmass behind it is seasonal at best. It’s the warmth ahead of it that’s making for the fireworks.

I am going to screen shot some model snowfall maps from the past few days and then compare them to what actually occurs. I bet the result will be laughable. 

[tamarack]

1 hour ago, CoastalWx said:

Rain for Tamarack and snow for DC. 

12/17/73 redux?  
Early evening conditions:
BGR 56°, 3" RA
NYC 25°, ZR
NNJ 15°, IP

[WinterWolf]

4 minutes ago, weatherwiz said:

I am going to screen shot some model snowfall maps from the past few days and then compare them to what actually occurs. I bet the result will be laughable. 

Agreed. Lol. Unless, this keeps jumping east? 

[powderfreak]

7 minutes ago, weatherwiz said:

I am going to screen shot some model snowfall maps from the past few days and then compare them to what actually occurs. I bet the result will be laughable. 

You should compare the SWE of any precip falling as snow… does anyone think 10:1 on a warm wet ground when it flips?

But could get 0.20” QPF as -SN at 34.5F that is a slushy 0.25” accum.  That’s what a 2.0” snow map is saying.

All the snow maps tell us is how much QPF as snow p-type, which is what I see when I look at them.  Do you guys look at it as accumulations?

[weatherwiz]

Just now, WinterWolf said:

Agreed. Lol. Unless, this keeps jumping east? 

Moreso with the totals. Some of the totals being spit out seem way too high. For ski country it's probably a different story though...they may get it good which is fantastic news for them. There doesn't seem to be an issue with the CAA in the llvls but the colder temperatures at the surface really look to lag. Where rates are intense that will offset this a bit but outside of ski country it could really have trouble sticking in many places.

[ORH_wxman]

Just now, weatherwiz said:

Moreso with the totals. Some of the totals being spit out seem way too high. For ski country it's probably a different story though...they may get it good which is fantastic news for them. There doesn't seem to be an issue with the CAA in the llvls but the colder temperatures at the surface really look to lag. Where rates are intense that will offset this a bit but outside of ski country it could really have trouble sticking in many places.

Most of the snow maps we see aren’t actually pure model output. They are snowfall algorithms using model data…which is why we have multiple options like 10:1 or Kuchera. There’s a reason I called them clown maps over 15 years ago, lol. 

[weatherwiz]

2 minutes ago, powderfreak said:

You should compare the SWE of any precip falling as snow… does anyone think 10:1 on a warm wet ground when it flips?

But could get 0.20” QPF as -SN at 34.5F that is a slushy 0.25” accum.  That’s what a 2.0” snow map is saying.

All the snow maps tell us is how much QPF as snow p-type, which is what I see when I look at them.  Do you guys look at it as accumulations?

As far as my understanding, the snow maps just take QPF falling as snow and then multiply it by a calculated ratio and that's it. I could be very wrong on this, but I've always assumed they don't really factor in much else. While I do think the snow maps can be very useful to aid in pinpointing where the gradient between rain/snow will be, oropgraphic influences, and what max totals may be, I don't think they provide any other value. As we know, during an event snowfall ratios are not constant and there are many factors which influence ratios; (snowgrowth, lift, moisture) and I don't believe the algorithms behind these maps incorporate these. 

[40/70 Benchmark]

3 minutes ago, ORH_wxman said:

Most of the snow maps we see aren’t actually pure model output. They are snowfall algorithms using model data…which is why we have multiple options like 10:1 or Kuchera. There’s a reason I called them clown maps over 15 years ago, lol. 

I like NARCAN and positive depth change maps the best, unless in a deformation area, then you can weight Kuchera much more aggressively.

[weatherwiz]

2 minutes ago, ORH_wxman said:

Most of the snow maps we see aren’t actually pure model output. They are snowfall algorithms using model data…which is why we have multiple options like 10:1 or Kuchera. There’s a reason I called them clown maps over 15 years ago, lol. 

They seem to do an excellent job in the mountains out West but that's about it  

[amc]

33 minutes ago, Ginx snewx said:

Imagine the rain rates at that wind shft line. CSI city 

Big bummer for southern coastal Maine... at one point the NAM was putting us into the 70mph gust zone... now it's really only downeast that's the jackpot for us anyway 

[OceanStWx]

3 minutes ago, weatherwiz said:

As far as my understanding, the snow maps just take QPF falling as snow and then multiply it by a calculated ratio and that's it. I could be very wrong on this, but I've always assumed they don't really factor in much else. While I do think the snow maps can be very useful to aid in pinpointing where the gradient between rain/snow will be, oropgraphic influences, and what max totals may be, I don't think they provide any other value. As we know, during an event snowfall ratios are not constant and there are many factors which influence ratios; (snowgrowth, lift, moisture) and I don't believe the algorithms behind these maps incorporate these. 

And that's usually going to be QPF x ratio for all frozen ptypes. Sleet? QPF x snow ratio. Rain/snow mix? QPF x snow ratio. 

That's why Kuchera attempts to bring in temps aloft to adjust those mixy situations down. 

2 minutes ago, 40/70 Benchmark said:

I like NARCAN and positive depth change maps the best, unless in a deformation area, then you can way Kuchera much more aggressively.

HRRR also has a variable density snow accumulation which can work pretty well.

[STILL N OF PIKE]

10 minutes ago, powderfreak said:

You should compare the SWE of any precip falling as snow… does anyone think 10:1 on a warm wet ground when it flips?

But could get 0.20” QPF as -SN at 34.5F that is a slushy 0.25” accum.  That’s what a 2.0” snow map is saying.

All the snow maps tell us is how much QPF as snow p-type, which is what I see when I look at them.  Do you guys look at it as accumulations?

Pretty sure that would have helped last year with the 33-34 snow that fell multiple times on CP that was modeled on clown maps to accumulate nicely . Our ratios were crap and most of the consistency was mashed taters from Nashua to KBED last year 

[MJO812]

Gfs looks nice in the mid range 

[40/70 Benchmark]

1 minute ago, OceanStWx said:

And that's usually going to be QPF x ratio for all frozen ptypes. Sleet? QPF x snow ratio. Rain/snow mix? QPF x snow ratio. 

That's why Kuchera attempts to bring in temps aloft to adjust those mixy situations down. 

HRRR also has a variable density snow accumulation which can work pretty well.

I get rusty sometimes in the offseason....are you implying Kuchera is best for the marginal events fraught with precipitation type issues?

[40/70 Benchmark]

2 minutes ago, STILL N OF PIKE said:

Pretty sure that would have helped last year with the 33-34 snow that fell multiple times on CP that was modeled on clown maps to accumulate nicely 

Its can be tricky though because sometimes models can underestimate height crashes with a rapidly intensifying system and that ideology can back-fire. You have to view each system individually, but more often than not, you are right.

[CoastalWx]

Gfs drops part of the PV due to that AK block @ORH_wxman

[ineedsnow]

21 minutes ago, weatherwiz said:

I am going to screen shot some model snowfall maps from the past few days and then compare them to what actually occurs. I bet the result will be laughable. 

I think we can pull off a inch or two if we change over quick enough here

[powderfreak]

13 minutes ago, weatherwiz said:

As far as my understanding, the snow maps just take QPF falling as snow and then multiply it by a calculated ratio and that's it. I could be very wrong on this, but I've always assumed they don't really factor in much else. While I do think the snow maps can be very useful to aid in pinpointing where the gradient between rain/snow will be, oropgraphic influences, and what max totals may be, I don't think they provide any other value. As we know, during an event snowfall ratios are not constant and there are many factors which influence ratios; (snowgrowth, lift, moisture) and I don't believe the algorithms behind these maps incorporate these. 

Yeah I guess what I’m saying is it’s the amount of QPF the model thinks will fall as snow.  That’s it.  It just moves the decimal point.

The 4-panel P-Type maps are the same thing often for precip as snow.

Like if it shows 9.6” of snow, it just means 0.96” QPF is expected to fall from the sky in the form of a frozen crystal.  Whether it sticks, accumulates, etc or not is up to you.  You decide what to do with that information from there.

Edit: Yes we are saying the same things.  I just see a snow map and think in those terms… not that those inches will be on my yard when it’s done.

[OceanStWx]

3 minutes ago, 40/70 Benchmark said:

I get rusty sometimes in the offseason....are you implying Kuchera is best for the marginal events fraught with precipitation type issues?

Kuchera will be better  than 10:1 in the mixed zone, but where it is colder within the CAD it will be worse because ratios will still be about climo 10-12:1 and Kuchera will tend to make those 15+. 

[STILL N OF PIKE]

2 minutes ago, powderfreak said:

Yeah I guess what I’m saying is it’s the amount of QPF the model thinks will fall as snow.  That’s it.  It just moves the decimal point.

The 4-panel P-Type maps are the same thing often for precip as snow.

Like if it shows 9.6” of snow, it just means 0.96” QPF is expected to fall from the sky in the form of a frozen crystal.  Whether it sticks, accumulates, etc or not is up to you.  You decide what to do with that information from there.

 

That is where you get to then show your weenie nature or not 

[40/70 Benchmark]

3 minutes ago, OceanStWx said:

Kuchera will be better  than 10:1 in the mixed zone, but where it is colder within the CAD it will be worse because ratios will still be about climo 10-12:1 and Kuchera will tend to make those 15+. 

Right...thanks. I literally had that a$$ backwards. Like I said....middle age and the offseason are a bad combo. I think the proprietary NARCAN maps from F5 are some sort of modified Kuchera product.

There are a few instances when Kuchera can be fairly accurate when snow growth is ideal in a deformation zone, but that is not frequent...that is what I was thinking of.