December 5-6, 2020 Storm Observations and Nowcast

[CoastalWx]

Just now, OceanStWx said:

Most likely answer is that when the changeover occurred the thermodynamic profile didn't look like what we've described. The DGZ was likely lower in the atmosphere, and over time the WCB forced it to rise. Those mid level temps were way colder at 12z (despite surface temps being near 40) than they were at 00z (despite surface temps being near 33).  

Yeah and over time the DGZ dried out after it flipped, at least that’s what I noticed when I was looking at BOS. Radar started to shred a little. I think it was thumping good in those areas in metro west shortly after changeover and then went to crap after the DGZ rose and dried out a bit.

[OceanStWx]

Check out the GYX evolution. Whole sounding (including the DGZ) moves up and to the right, indicative of WAA (which you can see in one of the middle columns "inferred temp advection"). Right after the flip to snow you probably only had a 1-1.5km deep near freezing layer vs 3km later.

[ORH_wxman]

5 minutes ago, CoastalWx said:

Yeah and over time the DGZ dried out after it flipped, at least that’s what I noticed when I was looking at BOS. Radar started to shred a little. I think it was thumping good in those areas in metro west shortly after changeover and then went to crap after the DGZ rose and dried out a bit.

Yeah you’re left with like these -5C needles falling into that deep 32-33F layer. Not a good combo for efficient accumulation is an understatement. 

[Damage In Tolland]

This may be the only time we see something like this , this winter .

 

[CoastalWx]

LOL October keeping me above climo for now. 

[PhineasC]

Deep winter feel in Randolph. 

[WinterWolf]

9 minutes ago, CoastalWx said:

LOL October keeping me above climo for now. 

Hey..whatever it takes lol. 

[WinterWolf]

3 minutes ago, PhineasC said:

Deep winter feel in Randolph. 

Phin, are you on the east side of the whites/presidentials? 

[Baroclinic Zone]

9 minutes ago, WinterWolf said:

Phin, are you on the east side of the whites/presidentials? 

North

[PhineasC]

But the lodge is cozy. 

[ORH_wxman]

This crap was like slime and then froze overnight. Back in holliston we got about 4” of Italian ice. But the piles make it look like double that because of the water content. 

[STILL N OF PIKE]

6 minutes ago, PhineasC said:

But the lodge is cozy. 

You are the New Caretaker at the beautiful Overlook ..view 

[tamarack]

After seeing nearby cocorahs reports I can't be too critical of snow total verification.  Chesterville, 7-8 miles to my SW, reported 2.9" from over 2" total precip, not quite half my 6.0 and with considerably more precip.  12 miles to my WSW, the Temple observer at 1220' had 11.5".  3 stations, all within less than a 30 minute drive from each other, and a 1-2-4 ratio of snowfall.  

[wxsniss]

Yeah I see it now, thanks all, it really was that simple.

The changeover had transiently good lift through the DGZ, I guess enough to cool soundings to keep it snow thereafter. But lift dropped and stayed low while we were supposed to be rocking in a comma head.

These are from 12z 3k NAM, before (21z), ~during (00z, I know in reality changeover was around 21z), and after (02z):

[HoarfrostHubb]

1 hour ago, Ginx snewx said:

Rain totals

Wow   8.5" on 1.6ish precip... some was straight rain, but not a lot here.  Prob 1.5" was snow... so 5.7 : 1 ratio cement

[wdrag]

Hi.  My wrap addition.    Added snow reports that were accepted by the NWS and the lightning archive. 

While one can argue on the use of models and models vs pattern recognition, one difficulty continues over the years... use of 10 to 1 snow ratios. We need to be careful about this. NWS has a blended snow ratio tool (every 6 hours or less which can be interpolated). Overall model intent was good (except the one day of  a very westward set of solutions) but model snowfall was way overdone on amounts Southern NH southward that performed  the phase change reasonably well (NAM/EC).  The over-forecast was probably due to the occurrence of wet snow during 33-34F air temp, non frozen ground and much of it during daylight hours. My guess (there may be some verification out there?) was a 6 to 1 snow water ratio (if someone can provide some documentation on ratio-that would be helpful)?  This especially since many folks were speaking or imaging large flakes (DGZ ideal or less than ideal).

Snow accumulation may have as much or nearly as much to do with ratios as DGZ.   I always start with total positive snowfall change, then check the usually heavier Ferrier, and then IF frozen ground and lower thicknesses below 5380 DM - I will look to as much as 10 to 1 or Kuchera.  These are painfully earned considerations over my life.  

I may be wrong on Kuchera... but my guess is Kuchera does not take into account 33F melting that was modeled in the EC 2m temps?  Maybe it does... Sometimes Kuchera works excellent, but my experience is that it is best when clearly the sounding does not allow any melting or wet snowflakes (colder scenarios). 

Hopefully this makes sense.  I'm open to better science- if you have it, please add it (I do not have BUFKIT). 

 

My second thoughts and CT did add something recently on this...  This elevation snowstorm (event?) while not the biggest ever (never was supposed to be), not only placed ORH a foot temporarily ahead of normal, the daily record setting 9.6" was also about 14-15% of the climate 1981-2010 normal.   Since the general thinking here our forum and elsewhere, is a La Nina winter and below normal snowfall... it may be that ORH received 20% of it's seasonal total (normal is 64.1")????? I don't know.  

Whether we may have paid too much attention to yesterdays storm,  it was probably an important one for this winter at ORH.  I fervently hope that I'm wrong and we don't look back at this early Dec snowstorm, as the biggie (like last cold seasons Dec 1-2 event).  

arghhhh 

[Lava Rock]

Very elevation dependent storm. At 300' only a few inches of snow and nothing on trees. Up by our house at 730', big difference. Lots of birch benders. Last pic is Long Lake, Naples

[Damage In Tolland]

10 minutes ago, wdrag said:

Hi.  My wrap addition.    Added snow reports that were accepted by the NWS and the lightning archive. 

While one can argue on the use of models and models vs pattern recognition, one difficulty continues over the years... use of 10 to 1 snow ratios. We need to be careful about this. NWS has a blended snow ratio tool (every 6 hours or less which can be interpolated). Overall model intent was good (except the one day of  a very westward set of solutions) but model snowfall was way overdone on amounts Southern NH southward that performed  the phase change reasonably well (NAM/EC).  The over-forecast was probably due to the occurrence of wet snow during 33-34F air temp, non frozen ground and much of it during daylight hours. My guess (there may be some verification out there?) was a 6 to 1 snow water ratio (if someone can provide some documentation on ratio-that would be helpful)?  This especially since many folks were speaking or imaging large flakes (DGZ ideal or less than ideal).

Snow accumulation may have as much or nearly as much to do with ratios as DGZ.   I always start with total positive snowfall change, then check the usually heavier Ferrier, and then IF frozen ground and lower thicknesses below 5380 DM - I will look to as much as 10 to 1 or Kuchera.  These are painfully earned considerations over my life.  

I may be wrong on Kuchera... but my guess is Kuchera does not take into account 33F melting that was modeled in the EC 2m temps?  Maybe it does... Sometimes Kuchera works excellent, but my experience is that it is best when clearly the sounding does not allow any melting or wet snowflakes (colder scenarios). 

Hopefully this makes sense.  I'm open to better science- if you have it, please add it (I do not have BUFKIT). 

 

My second thoughts and CT did add something recently on this...  This elevation snowstorm (event?) while not the biggest ever (never was supposed to be), not only placed ORH a foot temporarily ahead of normal, the daily record setting 9.6" was also about 14-15% of the climate 1981-2010 normal.   Since the general thinking here our forum and elsewhere, is a La Nina winter and below normal snowfall... it may be that ORH received 20% of it's seasonal total (normal is 64.1")????? I don't know.  

Whether we may have paid too much attention to yesterdays storm,  it was probably an important one for this winter at ORH.  I fervently hope that I'm wrong and we don't look back at this early Dec snowstorm, as the biggie (like last cold seasons Dec 1-2 event).  

arghhhh 

Around NE CT here it was 3.75:1 ratio

 

[Whineminster]

3 hours ago, Damage In Tolland said:

What’s your elevation there? That looks up there . Is that Wachusett in background?

Just under 1,100'.  Yeah that's wachusett. My pack retention isn't great though do to my south exposure. 

[STILL N OF PIKE]

At ASH , we got 1 inch QPF After 2pm and it led to maybe an inch of snow for a 1:1 ratio as it was 98% snow lol

 

At Miller state park they had well over a foot at  1600’  (got a settled depth of just over 13”) around that elevation . Much above that was impossible  to measure as less trees and serious blowing and drifting on exposed NW spots

 

[wokeupthisam]

About 1 foot, tough to measure due to late drifting.  Just a pasting for the first 3/4 of the storm, snowed hard with temp at 32.2 most of that time.  Power went out at 10:30pm and still out.

 

[Lava Rock]

Power back on after 20hrs. Feels and looks wintery

[rimetree]

Under performed here. 2" measured this morning. Snow was nice to look at last night and very wintery feel today with some blowing snow. Went for a walk around the neighborhood and noticed the crackling sound in the trees when the wind blew enough to fracture the ice clinging to the branches. My old place in Nottingham must have done fairly well.

[STILL N OF PIKE]

I know nobody cares but in the name of accuracy my measurements were actually at about 200 feet higher elevation than I thought , going back and cross referencing topo maps and measurements taken at a couple notable spots (where trail bent 180 and Just shy of A pleatau with open view of Monadanock) . My ski tracks altitude wasn’t reading and I shouldn’t have listed the elevation before checking .

[jbenedet]

Still getting stink bugs and leaf footed bugs in my place. 

Lawn is green. 

A few herb plants I never harvested in the garden are still alive..

Met Winter still a ways off....

 

[Weatherlvr]

7 hours ago, dendrite said:

Hooksett damage

Northfield damage

 

Other than the cable line, nbd here. I saved the bamboo and birches with frequent shaking. The birches will hopefully recover. As for my parents, at least they’ll get more sun. 

We ended up with nothing here across the lake is white recorded a 39.5 mph gust sustained 25.4mph winds at 10pm to 12am last night.  

[Lava Rock]

As soon as I put genny away, power went back off. Classic

[Damage In Tolland]

Just now, Lava Rock said:

As soon as I put genny away, power went back off. Classic

Yes!

[Yukon Cornelius]

44 minutes ago, Lava Rock said:

As soon as I put genny away, power went back off. Classic

We just got ours back after about 14 out. Changed the oil and got the genny all put away and just hoping we don’t lose it again.  My connection is outside at the opposite end of the house, so dragging that beast out of the garage last night at 1:00am through the frozen cement and dropping limbs is not the kind of fun I’m looking to repeat. 

[Great Snow 1717]

58 minutes ago, jbenedet said:

Still getting stink bugs and leaf footed bugs in my place. 

Lawn is green. 

A few herb plants I never harvested in the garden are still alive..

Met Winter still a ways off....

 

Lawns have the look of  mid to late April. As of friday there were a few dandelions in the yard.