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Wednesday 12/11 SNE Snow Threat


The 4 Seasons
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1 minute ago, The 4 Seasons said:

Final totals across the state vs. final call forecast. If there are any new or updated reports ill add them or if anyone has anything they want to add. I'm using my final call as always for verification, if i didn't chop the range down from 2-5 it would have been perfect. Grade: A

12_11.19_snow_totals.thumb.jpg.e8c1b53af0288a73f327317f5d834150.jpg

12_09.19_forecast_2.thumb.jpg.98cff069955c45d45f1be1349e07c647.jpg

can't get better than that 

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4 minutes ago, The 4 Seasons said:

except for my first call was 2-5 lol, thats why i gave it an A and not A+. But i did bump up numbers in the litchfield hills and glad i did.

First Call, about 32 hours lead time

12_09.19_forecast_1.thumb.jpg.4da52fa1e0ecb80f09dde873537cf335.jpg

hey you adjusted as necessary...nothing wrong with that. You saw the trends and acted...and rightfully so 

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26 minutes ago, weatherwiz said:

I'll chime in as well. 

Do you have bufkit, Ray? If not coolwx.com has great tools to see what you could with bufkit.

coolwx.com > Hourly forecast models > then you can choose plot, station, and model on the left hand side.

Here is the 0z 3K NAM for BDL:

1. the -12C to -18C range is illustrated...this is where snow growth is most optimized

2. I highlighted by the purple box where the negative values of omega area (negative values of omega indicate rising motion). Notice how you have very negative values of omega right inside the snowgrowth zone...this is referred to as a "cross hair signature". When this occurs and you have sufficient ice and RH in this layer (what's great about bufkit is you can overly RH with this...I'll post an example) you're not only going to maximize snow growth...but you're going to get very intense precip rates

3. I circled area of dry air in the low-levels around 6z or so...that was my flag for all this

 

Now let's look at the RH profile. The time of snow was prior to 12z...well the heaviest anyways. Notice something...very moist...the dry air in the lower levels doesn't take over until around 12z...AFTER the precip has fallen. My mistake here was harping that drier air would be in place earlier...but between 0z-12z...you have a very deep moist profile here (noted by the high RH values through the troposphere

 

 

Yep, BUFKIT is definitely your best friend when it comes to looking at the DGZ and trying to find funky dry layers. That BDL cross-section is an excellent signature for a short period of heavy high ratio snow. Of course BUFKIT and coolwx is limited to the American models. You can get some coarse SKEW-Ts for the globals but I don't know if there is anywhere to get cross-sections. Checking the cross-sections is good practice for any snow forecast. Sometimes you can find some flags.

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1 minute ago, DomNH said:

Yep, BUFKIT is definitely your best friend when it comes to looking at the DGZ and trying to find funky dry layers. That BDL cross-section is an excellent signature for a short period of heavy high ratio snow. Of course BUFKIT and coolwx is limited to the American models. You can get some coarse SKEW-Ts for the globals but I don't know if there is anywhere to get cross-sections. Checking the cross-sections is good practice for any snow forecast. Sometimes you can find some flags.

I'd kill to be able to get BUFKIT data for the EC/GEM/UKMET.

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55 minutes ago, dendrite said:

Yeah but that was 10:1 right? Maybe QPF overperformed a bit, but the banding looked pretty good so that's not too surprising. I didn't see coco obs, but I assume some of the bigger totals were pushing 15-20:1?

That's right....I just missed the boat here...

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1 hour ago, dendrite said:

00z 3km NAM from last night...cross sections through that banding. You can see the omega bullseye "crosshaired" through that max DGZ of -12C to -18C. That's pretty damn high up at 500mb, but if you look at the lower image the RH was high enough for deposition with respect to ice. Also, it was just moist enough in the low levels to prevent virga. This suggests a pretty sharp cutoff though with the sinking air just west of the banding and lower RH.

 

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Yes excellent representation 

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