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The Blizzard of the Ides, 2017 ...observation time


Typhoon Tip

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14 minutes ago, wxsniss said:

Some thoughts as dry slot is almost here:

1) Was there a single model that had a good handle of this storm?

Euro: too cold in eastern SNE, was still showing 1 foot snow in Boston 0z last night 7 hours before start. Way too high on qpf in most of SNE.

RGEM: had rain all the way to Worcester

GFS: no

Maybe the Op NAM? Para-NAM seemed too cold.

 

2) Why were basically 100% of models way too high on qpf in most of SNE? I mean Euro was showing > 2" Philly-NYC-all of SNE last night. That was part of why forecasts busted way too high as we expected a much better rates pre-changeover.

 

3) Boston basically had ~2-2.5 hours of heavy snow with decent snowgrowth beginning 11:30. NWS / TV and otherwise forecasts busted too high across the board, but it was close. The poor snow growth since 2pm and eventual changeover robbed us an additional 3-4 inches between 2-4pm.

 

4) Regarding the poor snowgrowth around 2-4pm... I expected much better from soundings... seems like good DGZ omega and saturation, plenty cold column. Here was 1hour RAP for 18z KBOS:

 

Re #1 ...it depends on what aspect:  The models handled the advent of a system remarkably well...picking up on a storm way in advance and despite some arguable more or less impacting model cycle depictions, they persisted.  

If we want to get into details and particulars... like timing rain vs snow and amounts --- Oy yoi yoi.. Perhaps some of that ambiguity could have been cleared up by a pure phase.. We got into trouble with this guy because he wasn't really shaking hands between steams too well, and that sort of tilted the system and made for warm layers and dry-slots and other migraines.  

Re #2 ...probably should let the system truly wind down before assessing but ... yeah, it appears 1 to 1.5" should do it; perhaps half ?  I'm less than certain about the exact numbers and that's also yet to be determined.. It may be the source region for the southern component having a hefty PWAT source.  QPF is not a very good metric in atmospheric modeling though anyway?  It's actually not uncommon for x-y-z locations to bust high or low regardless of predictability of event. 

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7 minutes ago, wxsniss said:

Some thoughts as dry slot is almost here:

1) Was there a single model that had a good handle of this storm?

Euro: too cold in eastern SNE, was still showing 1 foot snow in Boston 0z last night 7 hours before start. Way too high on qpf in most of SNE.

RGEM: had rain all the way to Worcester

GFS: no

Maybe the Op NAM? Para-NAM seemed too cold.

 

2) Why were basically 100% of models way too high on qpf in most of SNE? I mean Euro was showing > 2" Philly-NYC-all of SNE last night. That was part of why forecasts busted way too high as we expected much better rates pre-changeover.

 

3) Boston basically had ~2-2.5 hours of heavy snow with decent snowgrowth beginning 11:30. NWS / TV and otherwise forecasts busted too high across the board, but it was close. The poor snow growth since 2pm and eventual changeover robbed us an additional 3-4 inches between 2-4pm.

 

4) Regarding the poor snowgrowth around 2-4pm... I expected much better from soundings... seems like good DGZ omega and saturation, plenty cold column. Here was 1hour RAP for 18z KBOS:

rap_2017031417_001_KBOS.thumb.png.1e88e9cef5e4d6dd641a7e44d8598c61.png

These systems that are one massive front end dump typically short change you despite having 4-6 hrs of insane conditions. It comes to the wet bias models have from very strong low level warm air advection in combination with less lift, warmer and drier air in the DGZ. That's why many were doubting those high numbers that Noyes and others had. Just remember to always take the under on exorbitant amounts with these setups. 

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1 minute ago, wxsniss said:

 

Actually was thinking about this last night... we were already around 30F in Boston last evening. Another sign that we were toast. Any "buffer" we would have had from that cold air mass 24 hours prior was squandered.

:D

squandered?  - or "Marched" ... maybe it's to be expected having two full days of sun a mere week before the Equinox ... Cold air or not... that's going to modulate some -

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2 minutes ago, 40/70 Benchmark said:

QPF is often often over modeled east of the H7 low, but I though that the low level convergence would have been of a bit more benefit.

This storm was very similar to Boxing day, minus the 18" band near Boston.

I'm not sure why the coastal from was essentially non-existant in this event. 

March, and also storm started to draw in lower level warmth.

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2 minutes ago, 40/70 Benchmark said:

What does that have to do with it?

 

Yes, all we heard about was how frigid the antecedent conditions would be, but is was seasonable cold leading into this storm.

It was not arctic.

I'm surprised we are still mostly snow

we must be around a foot now

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I'm thinking 13.5'' is final here. Snow went light quick and never really picked back up. Should've stuck with 12-20'' but fell for the very consistent model signal of 1.75''+ of liquid. When the Euro corroborates NAM QPF it's hard to say no. 

Awesome storm overall though. Don't see a lot of foot+ storms here. And certainly don't see 3+''/hr rates often, especially with average at best growth.

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In a system so intense as this where there is so much going on it's extremely unlikely that any one model will handle the storm great.  There are just too many complexities and too much mesoscale aspects for that to happen.  Have to look at each and every model and try to find what that model has been the most consistent with, know what each model's biases are for similar setups, climo, etc.  IMO, when dealing with these setups which show potential you have to look back at other monster events and see exactly how things transpired.  If looking at the setup and there are numerous flags that is a big eye opener that it may not pan out.  Trends are very important and its silly to use statement's like "oh its the NAM" or "its the GFS" to discount potential outcomes.  

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1 hour ago, Dan said:

Much wetter snow than I expected, probably why the totals are a bit lower.  Some pretty crazy house rattlers out there tho.  Really impressive gusts at times.

 

10.5" here so far.  Biggest single storm total of the season, perviously 9.5"

Hi Dan,

 I just got back in from shoveling outside of my home in Methuen. A reasonable good estimate using a measuring stick is 12-13. Somewhat of an underperformer snowfall wise, but a overperformer sleet wise. A lot more sleet than what any forecaster had this morning for our area. Very heavy snow to say the least. 

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