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Jan 7 Two-Headed Coastal Obs


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Just now, moneypitmike said:

Just broke in the new snowblower.

It works. :)

Congrats. Mine didn’t work today…lol. The gear shifter is messed up. Prob a rusted gear wheel inside but not 100% sure. Thankfully there’s an older dude around the corner who repairs snow blowers so he’s gonna look at it tomorrow. 
 

At least this was a good storm to not have the snow blower. It was rpettt east to shovel this champagne powder. Only annoying part was the denser snow banks at each end of my horseshoe driveway. 

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1 minute ago, ORH_wxman said:

Congrats. Mine didn’t work today…lol. The gear shifter is messed up. Prob a rusted gear wheel inside but not 100% sure. Thankfully there’s an older dude around the corner who repairs snow blowers so he’s gonna look at it tomorrow. 
 

At least this was a good storm to not have the snow blower. It was rpettt east to shovel this champagne powder. Only annoying part was the denser snow banks at each end of my horseshoe driveway. 

That blows (haha).  True on this being a good one for it to break on.

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2 minutes ago, ORH_wxman said:

Congrats. Mine didn’t work today…lol. The gear shifter is messed up. Prob a rusted gear wheel inside but not 100% sure. Thankfully there’s an older dude around the corner who repairs snow blowers so he’s gonna look at it tomorrow. 
 

At least this was a good storm to not have the snow blower. It was rpettt east to shovel this champagne powder. Only annoying part was the denser snow banks at each end of my horseshoe driveway. 

The banks are always the worst, especially when you 15-20 inches and it's not powdery, its usually a heavy snow.

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Snowing Hard again.  This is  quite nice.  But just gets me closer to the number I Want so badly that I’ll never get to in 12.  

2 hours ago, DotRat_Wx said:

God please kill me 

And we are free to complain on hereDOT haha.  I don’t just whine, I give Very detailed specifics on my complaining, so you’re given a chance to clap back at specifics you know.  Vs. one big eye roll.  

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10 minutes ago, TheSnowman said:

Snowing Hard again.  This is  quite nice.  But just gets me closer to the number I Want so badly that I’ll never get to in 12.  

And we are free to complain on hereDOT haha.  I don’t just whine, I give Very detailed specifics on my complaining, so you’re given a chance to clap back at specifics you know.  Vs. one big eye roll.  

Specifically, you're a wanker.

 

5 minutes ago, CoastalWx said:

Kids trampling pack ftl. 
 

FA9BFCB8-D9AD-478B-A8E6-BD4F701ACEC4.jpeg

4EA9774B-E5DD-4E0A-B67D-75F2CBD73120.jpeg

ftw, friend...ftw. They enjoy it more than we do.

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Let's try to clear up some things I've read:

1) Almost all NWP models (if not, all) provide liquid water equivalent (LWE) and snow water equivalent (SWE) as diagnostic fields. When I write, "diagnostic fields" this implies that both variables, LWE and SWE, is calculated within the model itself between modeled time steps. Modeled time steps are ~27 seconds depending upon the horizontal resolution of a modeling system. Regardless, the calculation of LWE is straightforward.

LWE  = the liquid accumulation of all hydrometeor contributions diagnosed by a modeling system

The calculation of SWE varies by microphysics (mp) scheme. I'll give one example - one (there are many) mp scheme calculates fall rates for snow, pristine ice (I consider this sleet), graupel, and rain. Thus, fall rates can be converted into hydrometeor accumulation by multiplying by the modeled time step. Once the time stepped accumulation is obtained, SWE becomes  - SWE = snow + sleet... 

Just keep in mind that SWE is often used to determine snowfall for all private/public websites. Since almost all mp schemes includes sleet within their routines, SWE may be overdone due to sleet contamination (for regions that mix). Thankfully, most websites make this clear.

2) mp schemes are reliable at fine grid scales (<3km). They can consider heat, moisture, and momentum flux caused by convection without parametrization. At larger scales (>12km), convective parameterizations are required to essentially approximate convictive processes. Although I'm not entirely sure, I believe cumulus parameterization from global models, to regional models, then to mesoscale models caused some forecasting problems for today's event.

Just a thought!

3) The land surface model (LSM) of all NWP models includes a snow depth field that does determine new snowfall. Unfortunately, the algorithm is usually two-dimensional and the output isn't archived in gridded output... Delta snow depth (often provided by websites) will almost always be underdone since it includes gauge losses between the ground-snow and air-snow interface.

4) Anyone ever notice ''6-hour averaged Precip Rate" which is plotted by precipitation type? Think about it, does that make sense? No... They take an accumulated product (over the past 6 hours in this case), and use an instantaneous field to plot precipitation intensity by precipitation type. This is why you occasionally see snowfall along a cold front. Precipitation fell before the front passed (likely in a warm sector), BUT they use atmospheric fields post-frontal passage to determine precipitation type. This is no bueno imo.

5) Last one. Since snowfall is post-processed by most websites (excluding the ICON - I'd like to know what 'true SLR' means), keep in mind that they need instantaneous fields to calculate snow ratios. If output is provided every 6 hours, imagine how inaccurate snowfall may be when using instantaneous fields.

I said this once, I'll say it again: Websites need to be descriptive. Especially as it relates to snowfall products.

 

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8 minutes ago, wxsniss said:

Per Box twitter:

As of 1 PM, here are how our climate sites stand in terms of snowfall from the season's first major winter storm: 

#Boston - 11.2 inches
#Worcester - 6.2 inches
#Providence - 5.9 inches
#Hartford - 5.4 inches

Snowiest January since 2018, and the great pattern is just getting started based on the long range guidance. This is why its good to let the winter develop and give it a chance before writing it off. When I made that panic room threat things looked bad, but I jumped the gun there.

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7 minutes ago, MegaMike said:

4) Anyone ever notice ''6-hour averaged Precip Rate" which is plotted by precipitation type? Think about it, does that make sense? No... They take an accumulated product (over the past 6 hours in this case), and use an instantaneous field to plot precipitation intensity by precipitation type. This is why you occasionally see snowfall along a cold front. Precipitation fell before the front passed (likely in a warm sector), BUT they use atmospheric fields post-frontal passage to determine precipitation type. This is no bueno imo.

Indeed I have. Sim radar, for the models that have it, will always show a more accurate "in time" look at the storm's forecasted existence. Average precip rate is always lagging the actual storm evolution.

7 minutes ago, MegaMike said:

5) Last one. Since snowfall is post-processed by most websites (excluding the ICON - I'd like to know what 'true SLR' means), keep in mind that they need instantaneous fields to calculate snow ratios. If output is provided every 6 hours, imagine how inaccurate snowfall may be when using instantaneous fields.

HRRR seems to also have an explicit snow forecast, at least based on the (?) info screen on pivotalweather. Although it seems boilerplate so probably worth confirming. And also very possible that not all model sites use it for their graphics.

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4 minutes ago, MegaMike said:

Let's try to clear up some things I've read:

1) Almost all NWP models (if not, all) provide liquid water equivalent (LWE) and snow water equivalent (SWE) as diagnostic fields. When I write, "diagnostic fields" this implies that both variables, LWE and SWE, is calculated within the model itself between modeled time steps. Modeled time steps are ~27 seconds depending upon the horizontal resolution of a modeling system. Regardless, the calculation of LWE is straightforward.

LWE  = the liquid accumulation of all hydrometeor contributions diagnosed by a modeling system

The calculation of SWE varies by microphysics (mp) scheme. I'll give one example - one (there are many) mp scheme calculates fall rates for snow, pristine ice (I consider this sleet), graupel, and rain. Thus, fall rates can be converted into hydrometeor accumulation by multiplying by the modeled time step. Once the time stepped accumulation is obtained, SWE becomes  - SWE = snow + sleet... 

Just keep in mind that SWE is often used to determine snowfall for all private/public websites. Since almost all mp schemes includes sleet within their routines, SWE may be overdone due to sleet contamination (for regions that mix). Thankfully, most websites make this clear.

2) mp schemes are reliable at fine grid scales (<3km). They can consider heat, moisture, and momentum flux caused by convection without parametrization. At larger scales (>12km), convective parameterizations are required to essentially approximate convictive processes. Although I'm not entirely sure, I believe cumulus parameterization from global models, to regional models, then to mesoscale models caused some forecasting problems for today's event.

Just a thought!

3) The land surface model (LSM) of all NWP models includes a snow depth field that does determine new snowfall. Unfortunately, the algorithm is usually two-dimensional and the output isn't archived in gridded output... Delta snow depth (often provided by websites) will almost always be underdone since it includes gauge losses between the ground-snow and air-snow interface.

4) Anyone ever notice ''6-hour averaged Precip Rate" which is plotted by precipitation type? Think about it, does that make sense? No... They take an accumulated product (over the past 6 hours in this case), and use an instantaneous field to plot precipitation intensity by precipitation type. This is why you occasionally see snowfall along a cold front. Precipitation fell before the front passed (likely in a warm sector), BUT they use atmospheric fields post-frontal passage to determine precipitation type. This is no bueno imo.

5) Last one. Since snowfall is post-processed by most websites (excluding the ICON - I'd like to know what 'true SLR' means), keep in mind that they need instantaneous fields to calculate snow ratios. If output is provided every 6 hours, imagine how inaccurate snowfall may be when using instantaneous fields.

I said this once, I'll say it again: Websites need to be descriptive. Especially as it relates to snowfall products.

 

Thanks for the detailed post. I’ve always despised the model snow maps (or clown maps as I call them) and this is another great description of why they stink. They are fun to look at for sure…but they do often cause a lot of confusion and often inflate expectations compared to usual. 
 

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36 minutes ago, dryslot said:

Wish i would've been sitting on top of the Cashes Ledge Buoy earlier today, Looked like 2"+/hr rates there.

And we know that with those rates snow will accumulate even on a warm surface.

Might be up to 1.5" here, or even 1.7 to take 3rd place for the season's biggest.

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13 minutes ago, wxsniss said:

Per Box twitter:

As of 1 PM, here are how our climate sites stand in terms of snowfall from the season's first major winter storm: 

#Boston - 11.2 inches
#Worcester - 6.2 inches
#Providence - 5.9 inches
#Hartford - 5.4 inches

I'm pretty much in line with the other 3 sites. I should gone into work in Chelsea...they probably had like 10" lol

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Was outside for 90 min as a nice light snow fell to end things . Joined my GF’s kids in a neighborhood snowball fight (had to really pack them down to get a snowball ) but was just a great wintery day and scene . No mixing , no rain , just a snow storm . Kids loved it 

I did manage several direct hits which is always rewarding lol

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