HECS Checklist.....What to Look for to Avoid

[Huffwx]

This was my favorite blowing and drifting storm overall. This is one of the reasons why.

A+ photo.

[Tropopause_Fold]

Well we see it happen frequently, but in extreme rapidly deepening systems its hard to forecast. In the Dec 9, 2005 system, we saw everything collapse rapidly toward the ML center and eastern MA ended up in that CCB from hell....it was forecasted to be a bit further west originally. Its not easy to forecast those types of evolutions. We knew there would likely be two jackpots...and one of them was going to be aided by CF enhancement...but we also counted on it getting a bit of a boost in the final 6 hours of the storm with some of the leftover deformation and ML frontogenesis transfering E and NE. It just didn't happen this storm, and there's probably a lot of reasons we can come up with in hindsight, but that were not very forecastable before the storm.

But I always say never expect 20" unless the evidence is overwhelming, and it really wasn't in this storm. We knew someone would probably get 20" but we just didn't know who and where around here...and areas outside that were going to be left with something short of a HECS...granted it was slightly less than we thought because of some of the reasons we already mentioned.

yep.

i think i told kev via text everyone should be expecting 12-14...someone will get lucky with 18. he said that you were going 9-18, IIRC. i think the expectations of 20-30" over a large area sort of took on a life of their own.

ray, i think a lot of what you posted is on target. there's a lot of things that played into this going the way it did...and so many pieces are interrelated...but the two big things that frightened me away from the widespread 18+" stuff for SNE were:

1) the lack of either A) strong HP centered N of VT/NH/ME (as it was present in so many of our quintessential events as you know) or B. an antecedent airmass of arctic origin. this airmass was cold, no doubt, but not the jan' 05 type cold (if you want to draw comparison to an event that didn't have HP centered due north of us.) there was some good ll cold feeding into this system on the backside but the thermal gradients out ahead of it were not overly impressive as you alluded to. i think some of the better thermal forcing may actually have occurred down my way during the first half of the event. i think this also affected snow growth...even in BOS which was a relative jackpot, i went back and looked at NAM in bufkit and it actually could have been substantially better.

2) the ll and ml centers taking that circuitous route..from SSE to NNW from the carolinas toward LI, then making the turn E into ACK. go back through your kocin book and notice how many times in our better events the 850 lows ejected ENE from the MA and toward or under ACK. then check out some of the events that were less ideal and notice how often the 850 low took the more N/S trajectory similar to what this one took. i think what actually saved a lot of SNE from a potentially crappier solution was the pure bombogenesis that this thing underwent combined with the presence of some blocking. nao may have saved our butts this go around.

[Ginx snewx]

Good stuff Phil, do not tell Tip about the NAO though, LOL I thought early on theEuro runs a week earlier were the best. When I Looked at the 12 Z NAM banding site I was praying it was wrong, Dry slut city. All the occluded talk confused me too, dynamics weaken on occlusion

[HoarfrostHubb]

One of the better threads I have read, and another example why SNE in 2010 was dfficult.

When a storm like this gets so wound up, is the tendency of the max precipitation to go NW? And if so, what caused areas to the east (BOS, TAN) to do so well? Does the ocean provide additional moisture that the cf thrives on?

We need to build an ocean in Shirley...

[40/70 Benchmark]

Oh, you definitely want 5h to close off, there aren't many HECS ever that hit us without a closed 5h low. We just don't want to see it close off too soon and have most of the dynamics get shot to the SW of us and be a bit weaker by the time they reach us which is essentially what happened in this system. Obviously this was still a pretty big snowstorm for a large chunk of SNE, but to get those monster amounts, you need the best dynamics, and they never got here as we first thought they might.

Miller A storms are tedious for us because 5h often closes off too early and we rarely jackpot in those storms. Of all the SNE HECS, the majority are Miller Bs like Jan 2005, April '97, April '82, Feb '78, March '60.

Occasionally we can get HECS totals on Miller A storms like PDII and Jan '96 (for SE areas anyway)...but its generally tougher.

Yep....said it 100x; we give me a Miller B, anywday because Miller As develop further s and there is more time for somethiing to fook u. If you want a HECS, it's akin to a cat 5 cane; you can't have ANYTHING amiss and conditions MUST BE IDEAL.

An analogy you could draw is that if you want a cat 5 LF, you are better served to have a home brew because the chances of a CV system making it to the US as a cat 5 are slim to none.

Anytime I see a Miller A, I start wish for it evolve into a Miller B on subsequent runs....even in those cases you cited in which portions of the region received a HECS, the most prolific totals were found to out S in the ma.

If you remember, I was complaining when we saw the models closing this thing off in the ma and you tried to talk me of the ledge.....we ended up seeing it eek N, but not far enough.

When forecasting a HECS, especially across interior SNE: Miller A :"stay away".....Miller B: "come to me".

Will work out anout 9\10 times.

I don't think you can find a Miller A in which NE received the highest amounts.

[HoarfrostHubb]

Miller A's can become B's? How does that work? By the time it is a fully developed A, isn't it too late?

Rereading your post, I assume you mean it is modeling as an A, but has not actually become one... that makes sense.

Sorry.

[Ginx snewx]

Miller A's can become B's? How does that work? By the time it is a fully developed A, isn't it too late?

Rereading your post, I assume you mean it is modeling as an A, but has not actually become one... that makes sense.

Sorry.

A Miiler a traveling along the apps sine spits out a B over Hat which becomes the bomb.

[40/70 Benchmark]

yep.

i think i told kev via text everyone should be expecting 12-14...someone will get lucky with 18. he said that you were going 9-18, IIRC. i think the expectations of 20-30" over a large area sort of took on a life of their own.

ray, i think a lot of what you posted is on target. there's a lot of things that played into this going the way it did...and so many pieces are interrelated...but the two big things that frightened me away from the widespread 18+" stuff for SNE were:

1) the lack of either A) strong HP centered N of VT/NH/ME (as it was present in so many of our quintessential events as you know) or B. an antecedent airmass of arctic origin. this airmass was cold, no doubt, but not the jan' 05 type cold (if you want to draw comparison to an event that didn't have HP centered due north of us.) there was some good ll cold feeding into this system on the backside but the thermal gradients out ahead of it were not overly impressive as you alluded to. i think some of the better thermal forcing may actually have occurred down my way during the first half of the event. i think this also affected snow growth...even in BOS which was a relative jackpot, i went back and looked at NAM in bufkit and it actually could have been substantially better.

2) the ll and ml centers taking that circuitous route..from SSE to NNW from the carolinas toward LI, then making the turn E into ACK. go back through your kocin book and notice how many times in our better events the 850 lows ejected ENE from the MA and toward or under ACK. then check out some of the events that were less ideal and notice how often the 850 low took the more N/S trajectory similar to what this one took. i think what actually saved a lot of SNE from a potentially crappier solution was the pure bombogenesis that this thing underwent combined with the presence of some blocking. nao may have saved our butts this go around.

Man, great contribution from this thread by all...thx.

I suspected that may have been the case because this was esserntially a Dec 2000 that got shunted to the right at the last moment; saved most of us from significant taint, but outside of the cf enhancement, we still didn't receive much more snow because you can't account for the dynamics defecit as a result of the initial left hook.

I think we have all learned alot from this storm and year, so thought they may have superficially "screwed us", in the long run they did nothing of the sort.

This is what we have to do with 2010 and any other adversity that we encounter throughout life; conver it to personal enrichment.

Adversity undoubtedly facilitates growth, when the correct mindset is assumed; just part of the evoloution of life.

[40/70 Benchmark]

One of the better threads I have read, and another example why SNE in 2010 was dfficult.

When a storm like this gets so wound up, is the tendency of the max precipitation to go NW? And if so, what caused areas to the east (BOS, TAN) to do so well? Does the ocean provide additional moisture that the cf thrives on?

We need to build an ocean in Shirley...

Low level convergence; it's essentially another means by which to achieve the desired outcome....heavy snow.

N NJ, NYC, E NY state and parts of NNE did it via the mid levels, however coastal areas of e MA did via extra lift focused along and just to the west of the coastal front.

I was hoping to cash in on that, but the ageostrophic flow was too potent, so it setup to me se.

[Organizing Low]

great thread

lots to learn, as always.

[HoarfrostHubb]

Low level convergence; it's essentially another means by which to achieve the desired outcome....heavy snow.

N NJ, NYC, E NY state and parts of NNE did it via the mid levels, however coastal areas of e MA did via extra lift focused along and just to the west of the coastal front.

I was hoping to cash in on that, but the ageostrophic flow was too potent, so it setup to me se.

10 miles further east and you would have been in business (or more like SE)

So easy to get screwed in a setup like this past one, as you said.

Well, it is only Dec 28, year is about to close, Miller B's and SWFE on the way for Jan, Feb, then the March Miracle

[40/70 Benchmark]

10 miles further east and you would have been in business (or more like SE)

So easy to get screwed in a setup like this past one, as you said.

Well, it is only Dec 28, year is about to close, Miller B's and SWFE on the way for Jan, Feb, then the March Miracle

I think you mean west.....probably a little more than that. actually because it was pretty tight to the ocean.

[Logan11]

I think the lesson that should learned here is ...never expect a HECS even if the models forecast it. Just mentally prepare for a SECS and then you spare yourself a letdown when you get a 10 or 12 inch storm. I say that with a bit of sarcasm because nobody should be dissapointed with a foot. That is still a very nice snowstorm.

It just takes an almost perfect alignment to get a HECS and you may only get a half dozen of them in an average lifespan so this is going to be a frustrating hobby if ones goal is a HECS.

Well we always want the most snow, but you gotta be realistic I guess.

ENY was a huge heartbreak zone for some wx weenies with the sharp cutoff. A guy on one of the ALB channels just mentioned a tale of two towns in their viewing area.. 24" in Bennington (35 miles east) and a dusting in Fonda (35 miles west).

7" here and I had expected 6-10" so it was OK...it could have been a trace.

What should have tipped all of us off immediately was the sleet/snowgrains that mixed in for about 1-2 hrs. No model showed anything remotley close to mixing like that. Most all of us including mets brushed it off and said not to worry..When in reality it was a warning sign that something wasn't right

[HoarfrostHubb]

I think you mean west.....probably a little more than that. actually because it was pretty tight to the ocean.

If you were 10 miles further east/southeast...sorry

Push Wilmington to Wakefield/Saugus...

[40/70 Benchmark]

If you were 10 miles further east/southeast...sorry

Push Wilmington to Wakefield/Saugus...

Oh, ok.

[40/70 Benchmark]

I think the lesson that should learned here is ...never expect a HECS even if the models forecast it. Just mentally prepare for a SECS and then you spare yourself a letdown when you get a 10 or 12 inch storm. I say that with a bit of sarcasm because nobody should be dissapointed with a foot. That is still a very nice snowstorm.

It just takes an almost perfect alignment to get a HECS and you may only get a half dozen of them in an average lifespan so this is going to be a frustrating hobby if ones goal is a HECS.

Well we always want the most snow, but you gotta be realistic I guess.

ENY was a huge heartbreak zone for some wx weenies with the sharp cutoff. A guy on one of the ALB channels just mentioned a tale of two towns in their viewing area.. 24" in Bennington (35 miles east) and a dusting in Fonda (35 miles west).

7" here and I had expected 6-10" so it was OK...it could have been a trace.

Yea, it's like hoping for a perfect game every time that you watch a baseball game; it's best to watch because you love the sport, not to see a one in 10 year occurence.

I know this, yet I'll still do it.

[Logan11]

You're lucky in SNE that this thing did shove ENE ultimately after it got to that position SSE of Montauk. That saved you from a changeover situation and left you with a SECS anyway. That hook also deprived ENY from ALB N/W of a SECS because another 50 miles north before the hook and we would have been in 18" rather than 7".

But alas in this kind of event the band that gets true HECS snowfall is often narrow. In this case from Coastal NJ/Northeast NJ (NYC), north northeast across the Lower/Middle Hudson Valley, Berkshires into Southern Vermont.

Oh, ok.

[H2Otown_WX]

It had a warm core seclusion which is common of the deep Atlantic lows. I'm really hesitant to believe that CT had an above 0C layer in the column leading to sleet. I think the issue had to do with poor nucleation for growing snow crystals. I think I remember Gibbs posting an OKX sounding showing poor 700mb temps for nucleation and the dry air aloft didn't help either. As a result the snow growth was very poor and people were getting snow grains. The 1/4" diameter snow pellets that we even had up into C NH were caused by riming. So instead of getting the crystals to grow by deposition and getting actual snow "flakes" we were getting heavily rimed crystals. So although it was a relatively warm layer that ruined nucleation it wasn't necessarily a >0C layer. I think the only legit sleet was in SE MA where that warm nose snuck in aloft.

And btw Ray...good thread.

I don't know about others but my temperature actually rose during the storm which to me signifies some sort of WAA was going on perhaps in the BL or up at 850 mb. This was poorly modeled as while my temperature was rising places in SE NY had crashing temperatures. The low just came too close I guess that's what it comes down to for CT.

[H2Otown_WX]

You're lucky in SNE that this thing did shove ENE ultimately after it got to that position SSE of Montauk. That saved you from a changeover situation and left you with a SECS anyway. That hook also deprived ENY from ALB N/W of a SECS because another 50 miles north before the hook and we would have been in 18" rather than 7".

But alas in this kind of event the band that gets true HECS snowfall is often narrow. In this case from Coastal NJ/Northeast NJ (NYC), north northeast across the Lower/Middle Hudson Valley, Berkshires into Southern Vermont.

So ALB's 6-12" call worked out for you. I ended up getting 7" too while they were sounding alarms about a Blizzard warning and guaranteeing 1-2'.

[40/70 Benchmark]

You're lucky in SNE that this thing did shove ENE ultimately after it got to that position SSE of Montauk. That saved you from a changeover situation and left you with a SECS anyway. That hook also deprived ENY from ALB N/W of a SECS because another 50 miles north before the hook and we would have been in 18" rather than 7".

But alas in this kind of event the band that gets true HECS snowfall is often narrow. In this case from Coastal NJ/Northeast NJ (NYC), north northeast across the Lower/Middle Hudson Valley, Berkshires into Southern Vermont.

Like I said previously, I probably still would have recived several inches of snow before any turnover, but not quite the 1' I got.

Even in December of 2000 I managed about 5".....Boston was a different story.

[dendrite]

I don't know about others but my temperature actually rose during the storm which to me signifies some sort of WAA was going on perhaps in the BL or up at 850 mb. This was poorly modeled as while my temperature was rising places in SE NY had crashing temperatures. The low just came too close I guess that's what it comes down to for CT.

Of course there was some WAA...the frontogenesis ran N-S in E NY and WNE. What I'm saying is that it didn't get above 0C in the column.

[H2Otown_WX]

Of course there was some WAA...the frontogenesis ran N-S in E NY and WNE. What I'm saying is that it didn't get above 0C in the column.

Sorry, I'm a newbie. Yeah doubtful that we got above 0C but our ratios were total crap that's for sure.

[Jebman]

Epic thread - I'm learning tons even though I live in the S MidAtl. Just EPIC thread! +10000

[40/70 Benchmark]

Epic thread - I'm learning tons even though I live in the S MidAtl. Just EPIC thread! +10000

Feel free to join in.....I just didn't want to clutter the main thread and it may have been misperceived as a "whine thread"....

[dendrite]

Sorry, I'm a newbie. Yeah doubtful that we got above 0C but our ratios were total crap that's for sure.

Yeah...people think that cold temps always equals good ratios and they don't. Specific cloud temperatures produce certain crystals and the temp at the surface really plays no role unless you're dealing with 32F or greater air causing some melting of the flake. In the arctic this time of the year they typically don't receive high ratio snow. It's a dense, "dry" snow and their primary crystal types are columns and bullets because of their -20C to -40C cloud temps. You need to have cold enough temps in the clouds for nucleation to occur though. If your coldest cloud temp is only -4C you'll have no ice in the cloud and therefore no snow even if the entire column is below freezing.

[Jebman]

Feel free to join in.....I just didn't want to clutter the main thread and it may have been misperceived as a "whine thread"....

Thanks - I am most certainly NOT going to whine up your fine disco - I am really happy for New England. You guys take discussion to an entirely new level - Something I could sure learn from.

Thanks for this thread - It's like going to met college sans tuition.

Have an excellent New Year!

[40/70 Benchmark]

Yeah...people think that cold temps always equals good ratios and they don't. Specific cloud temperatures produce certain crystals and the temp at the surface really plays no role unless you're dealing with 32F or greater air causing some melting of the flake. In the arctic this time of the year they typically don't receive high ratio snow. It's a dense, "dry" snow and their primary crystal types are columns and bullets because of their -20C to -40C cloud temps. You need to have cold enough temps in the clouds for nucleation to occur though. If your coldest cloud temp is only -4C you'll have no ice in the cloud and therefore no snow even if the entire column is below freezing.

Too cold.... or no....

Thanks - I am most certainly NOT going to whine up your fine disco - I am really happy for New England. You guys take discussion to an entirely new level - Something I could sure learn from.

Thanks for this thread - It's like going to met college sans tuition.

Have an excellent New Year!

I actually meant folks from the mid atl may perceive me as whining, which would be understandable because I do alot of it.

You too!

[weatherwiz]

Great thread indeed!

This certainly was no easy storm to forecast..but then again, how many storms are "easy" too forecast?

Everyone has virtually touched upon what essentially went wrong here and when you really think about all the factors that went wrong and go back to when we were looking at the models and such we probably should have realized what EXACTLY we needed to see in place instead of just going about how things appear to be becoming together and what will happen if they do together.

I'm not sure if anyone out there was doing this but it would have been interesting to track the 700/500mb lows from the morning through the rest of the day...it seemed we were all worried about sfc low track and such...but if it was becoming clear that these mid-level lows were a bit west of model guidance maybe some of us could have picked this up and realized something good may not happen. Since the system was going through some incredible cyclogenesis and the system was becoming tightly wrapped all that essentially did was just suck in the dry air that was west and south of the system...remember there was a very deep trough in place and once the system was off the coast the return flow was from the north...pumping down dry air from Canada...this system was just pulling in way too much dry air and the only places that were saved were the places with the CF enhancement. I remember when looking at mesoscale analysis virtually all day two things remained rather constant...the BEST moisture convergence and mid-level frontogenesis existed across two area...NJ back towards NYC and SW CT and one in NE MA around the Boston area.

The last thing to note about that is the BEST moisture convergence and mid-level frontogenesis started setting up across the NJ/NYC/SW CT area about 2-4 hours or so before they started getting into the good stuff and the same thing occurred for NE MA area.

[40/70 Benchmark]

Great thread indeed!

This certainly was no easy storm to forecast..but then again, how many storms are "easy" too forecast?

Everyone has virtually touched upon what essentially went wrong here and when you really think about all the factors that went wrong and go back to when we were looking at the models and such we probably should have realized what EXACTLY we needed to see in place instead of just going about how things appear to be becoming together and what will happen if they do together.

I'm not sure if anyone out there was doing this but it would have been interesting to track the 700/500mb lows from the morning through the rest of the day...it seemed we were all worried about sfc low track and such...but if it was becoming clear that these mid-level lows were a bit west of model guidance maybe some of us could have picked this up and realized something good may not happen. Since the system was going through some incredible cyclogenesis and the system was becoming tightly wrapped all that essentially did was just suck in the dry air that was west and south of the system...remember there was a very deep trough in place and once the system was off the coast the return flow was from the north...pumping down dry air from Canada...this system was just pulling in way too much dry air and the only places that were saved were the places with the CF enhancement. I remember when looking at mesoscale analysis virtually all day two things remained rather constant...the BEST moisture convergence and mid-level frontogenesis existed across two area...NJ back towards NYC and SW CT and one in NE MA around the Boston area.

The last thing to note about that is the BEST moisture convergence and mid-level frontogenesis started setting up across the NJ/NYC/SW CT area about 2-4 hours or so before they started getting into the good stuff and the same thing occurred for NE MA area.

Messenger speacializes in that area and he was warning us of that, but it fell on deaf ears for the most part.

MattMOFO also mentioned it at one point.

I'd advise you pay closer attention to Messenger's posts in the future.

[DavisStraight]

I'm not sure if anyone out there was doing this but it would have been interesting to track the 700/500mb lows from the morning through the rest of the day...it seemed we were all worried about sfc low track and such...but if it was becoming clear that these mid-level lows were a bit west of model guidance maybe some of us could have picked this up and realized something good may not happen. Since the system was going through some incredible cyclogenesis and the system was becoming tightly wrapped all that essentially did was just suck in the dry air that was west and south of the system...remember there was a very deep trough in place and once the system was off the coast the return flow was from the north...pumping down dry air from Canada...this system was just pulling in way too much dry air and the only places that were saved were the places with the CF enhancement. I remember when looking at mesoscale analysis virtually all day two things remained rather constant...the BEST moisture convergence and mid-level frontogenesis existed across two area...NJ back towards NYC and SW CT and one in NE MA around the Boston area.

Is that why my temp went from 22 at the start and was up to 28 by 2am? I found that strange and worrisome at the same time.