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Last Hurrah Obs Thread: 3/13-15/23


WxWatcher007
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8 minutes ago, KoalaBeer said:

Thanks for this post. It definitely irks me when people trash a model without data to back it up. Admittedly I wish that data was easier to find…I’ve had this bookmarked for a while, and I think CSU used to have a good page… https://www.wpc.ncep.noaa.gov/html/modeldiag.html#verification 

Seems like it didn’t matter how many times with this event pro mets told everyone to toss the clown maps in the trash, people were still treating them like the gospel.

 

If people would look at the "total positive snow-depth change" instead of the 10:1 total snowfall maps their expectations would be more realistic.

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5 minutes ago, Ed, snow and hurricane fan said:

Is a 10:1 clown really bad (within a realistic time frame, not a week or hour 384), it gives a 'quick look' at what the model thinks will fall as snow, and can be easily adjusted for a different ratio?  Just a little more work on a 1 hour or three hour update to trim off QPF when it might be snowing but not sticking.

 

 

This is just my opinion 

But yes, they are really that bad. We'll use the two different methods, 10:1 and Kuchera. The Kuchera method was developed to help provide a more "accurate: assessment of ratios after all, we all know ratios can vary significantly. But (and as far as I know...this is where I could be wrong, hence the "this is just my opinion) all these products do is take a ratio and multiply it by QPF. 

Ultimately, snowfall production and accumulation are extremely complex and involve much more then just ratio and QPF. First off, snowfall ratios in themselves are extremely complex. They can change very rapidly during the evolution of the storm and can drastically within minutes. 

Degree of lift, abundance of moisture/ice crystals within the snow growth zone, thermal profile, moisture, CAA/WAA, evolution of the dynamics are all extremely critical in snowfall ratio and accumulation. 

Snow maps do provide value in they can help to quickly identify the gradient zones and where the cutoff can be expected and help identify local maxes and mins (the later though could easily be found by assessing numerous variable). 

 

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Just now, wkd said:

If people would look at the "total positive snow-depth change" instead of the 10:1 total snowfall maps their expectations would be more realistic.

Yes. Esp in lower elevations. They would’ve been horrible though in the hills and mountains. I think a lot of them had like 8-12” in N ORH hills and many of them pushing 2+ feet. 

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32 minutes ago, tunafish said:

I'm not disputing that as accurate given the location, elevation, and persistence of the band in that area all day...but...

I'm always skeptical of deck measurements, especially since most decks are attached to the house and right under the roof where drifting happens.  That one looks level with the rest of the deck at least...

I learned that in the 1993 Superstorm, was tracking 1.5-2"/hr on the deck and when it approached 10", I checked out the cul-de-sac and found ~6".   Low 20s and late afternoon so no delay in accumulation.
(That storm was one of the more disappointing 10"+ events in memory, as essentially every other site in New England had more, and the forecast had been 1-3 feet.  Warmth aloft caused heavy riming, such that my 1.70" LE only made 10.3".)

Moderate snow arrived about 4 PM, but without some inch-an-hour S+ we'll fall short of the 5-9" forecast.

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My criticism on the HRRR was about rates / QPF. My bad if that output isn't considered reliable for a meso within a few hours, I didn't know. HRRR was printing out ~0.2" liquid between 2 and 4 pm for I95 NW of boston (Malden, Arlington). This whole area has been in light precip or no precip for that whole time. I think that's a fair comment, and not just saying that the model sucks?

qpf_acc-imp.us_state_ne_s.png

weatherTAP_RadarLab_Image_20230314_2028.jpg

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11 minutes ago, ORH_wxman said:

Yes. Esp in lower elevations. They would’ve been horrible though in the hills and mountains. I think a lot of them had like 8-12” in N ORH hills and many of them pushing 2+ feet. 

The weenie maps were fine above 900 or so ‘

many spots will be well over 20 from New your upstate to Berks to VT to N orh county to monads . Many Of those areas will be 30-40 by midnight  . 
 

Globals couldn’t get close to resolving snow maps given how elevation dependent they were and with the orographic influences . 
 

 

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2 minutes ago, ORH_wxman said:

Yes. Esp in lower elevations. They would’ve been horrible though in the hills and mountains. I think a lot of them had like 8-12” in N ORH hills and many of them pushing 2+ feet. 

Absolutely true, but it is better for wienies like me to have snowfall exceed expectations than be disappointed when the 10:1 clown maps don't work out. Experienced mets usually have a better grasp of regional situations and know when modeled snow depth change is too low.

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