Feb 17 Miller A Threat

[UnionWeatherWx]

Wow, 12 hours to go from DC to NYC....slow moving snowline....

What do you mean by that?

[IsentropicLift]

Even though the overall precip shield is a good 30 miles further North, the moderate snow line is having a harder time coming North with it.

[IsentropicLift]

Coastal is about 1.5mb stronger

[IsentropicLift]

A very frustrating storm. One step forward and two steps backwards.

[snowman19]

The Euro ensembles aren't terrible. Look like the OP.

How about the sunday cutter?

[IsentropicLift]

So the Mid-Atlantic got wetter while further North got drier.

[coastalplainsnowman]

now all they have to do is stop acting like their audience is grandma, people with dementia and 3 year olds.

Absolutely! For kicks i tried watching mmhq or whatever it is called yesterday and that is *exactly* how the host (can't recall her name) was acting. 'Don't even think about going outside.' Then talking about the twc weather therapy dog, etc.

[ag3]

NAM has the .25" into Staten Island and the .10" line thru SWCT.

Not terrible.

[UlsterCountySnowZ]

northern precip shield is hitting a brick wall of confluence, you don't need a model to see it, you can clearly see the dry air winning In the north, most of which from spotter reports is falling as virga at the far northern edge

[IsentropicLift]

How about the sunday cutter?

Cutter on the mean, similar to the OP. Certainly looks like there is some decent spread.

[UnionWeatherWx]

northern precip shield is hitting a brick wall of confluence, you don't need a model to see it, you can clearly see the dry air winning In the north, most of which from spotter reports is falling as virga at the far northern edge

There is actually some moderate snow reports just south of D.C. Virga is barely a problem near DC, the precip fell within 10 minutes  of the radar showing it.

[UlsterCountySnowZ]

There is actually some moderate snow reports just south of D.C. Virga is barely a problem near DC, the precip fell within 10 minutes of the radar showing it.

I would concider DC the eastern extent, by northern shield I meant the majority of what's falling in Ohio and souther PA

And i wouldn't expect confluence to be an issue that far south

[UlsterCountySnowZ]

Latest RAP and HRRR bring some light snow in by about 3am

[UlsterCountySnowZ]

There is actually some moderate snow reports just south of D.C. Virga is barely a problem near DC, the precip fell within 10 minutes of the radar showing it.

For example, Lancaster OH is almost 75 miles south of the northern precip radar soundings... They're currently seeing 0 snowfall

[IsentropicLift]

Snow picking up in downtown DC

[SnowGoose69]

You can clearly see after 06-09Z the low bumps north slightly which is why LI, coastal NJ have a shot at getting in on decent snow.  The confluence was likely overdone again by the models slightly from the low departing SE Canada because the last few runs there has been an improvement over Cape Cod extending back to LI and coastal NJ

[Zelocita Weather]

Per NAM snow begins about midnight and last flurries end by 9-10am

[Guest Pamela]

You can clearly see after 06-09Z the low bumps north slightly which is why LI, coastal NJ have a shot at getting in on decent snow.  The confluence was likely overdone again by the models slightly from the low departing SE Canada because the last few runs there has been an improvement over Cape Cod extending back to LI and coastal NJ

 

 

As is often the case with East Coast storms, the models are beginning to align the isopleths (lines connecting points of equal precipitation) in a more NE / SW orientation (or at least ENE / WSW one) than the more E / W one that was depicted earlier. 

[UnionWeatherWx]

My dew point has gone up from -9 to -3.

[Guest Pamela]

As is often the case with East Coast storms, the models are beginning to align the isopleths (lines connecting points of equal precipitation) in a more NE / SW orientation (or at least ENE / WSW one) than the more E / W one that was depicted earlier. 

 

If you *did* have a purely east / west orientation to any snow pattern in the eastern US produced by a mid latitude cyclone...it might be hard pressed to generate copious amounts of moisture...as such a distribution would likely imply a rather zonal, flat flow...and a lack of a trough...a major buckle in the atmosphere often being the sine qua non of a large storm. 

[IsentropicLift]

Normally when we get shafted to the South you can easily see the confluince pressing down from the North on WV loop. But here it appears that the ULL to the Northeast is continuning to move out of the way and nothing is really pressing down on the flow. Unless the dry layers are at a different layer than what the WV loop shows.

 

 

Colder cloud tops also continue to advect Eastward.

 

[UlsterCountySnowZ]

4k NAM doesn't look good at all, precip makes it way in between 12-3am but is a broken mess

[Guest Pamela]

If you *did* have a purely east / west orientation to any snow pattern in the eastern US produced by a mid latitude cyclone...it might be hard pressed to generate copious amounts of moisture...as such a distribution would likely imply a rather zonal, flat flow...and a lack of a trough...a major buckle in the atmosphere often being the sine qua non of a large storm. 

 

Exceptions might include waves riding along east / west oriented quasi stationary fronts...but again, that would be a wave rather than a large storm.

[WeatherJeff1019]

I agree you wouldn't have any clue that this would be suppressed looking at that.... Doesn't match up to what I had envisioned by the models at all... We shall see

Normally when we get shafted to the South you can easily see the confluince pressing down from the North on WV loop. But here it appears that the ULL to the Northeast is continuning to move out of the way and nothing is really pressing down on the flow. Unless the dry layers are at a different layer than what the WV loop shows.

Colder cloud tops also continue to advect Eastward.

[Winter201415]

4k NAM doesn't look good at all, precip makes it way in between 12-3am but is a broken mess

your not supposed to look at the 4k nam for precipitation shield. It's always broken up and always less than what it really is!

[RU848789]

Not to get into some extended debate on the topic but I did just see your reply and wanted to comment.  The Law of Averages, luck or random chance, and the idea of things evening out are very significant factors in how things come together in the universe...note the snowless 70's & 80's in this region...after those years, would it seem reasonable to anticipate the avalanche of snow the region has seen in the last decade and a half?  Things even out over time...that's what climatology is...a series of deviations from the mean...but over time...the mean is generally satisfied & fulfilled.

When I went for a rather small amount of snow for NYC this season, the verbiage in my commentary gave a nod to this concept; i.e. that the city had been amazingly lucky for many years in a row, snow wise, and, eventually that luck would have to run out.  Who would not agree that there have been an exceptional number of chances for NYC to cash in on some big snows this winter...but they simply have been quite unlucky...it is not as if it was a warm & dry winter...and nearby Boston has seen practically 100 inches of snow already.

 

 

No offense, but that's not how probability works. The law of averages is a real phenomenon but does not apply to individual instances.

See RUs excellent explanation back in the thread. And I'm a professional data scientist so hopefully that carries some weight.

 

Yep, probability for random, independent events simply doesn't work that way.  The Law of Averages as used by laymen is almost always misused.  In statistical theory, random variables (and presumably the amount of snow per winter season is random each year) will average out at the statistical mean over a very large sample size (i.e., a very long time - centuries, for seasonal snowfall).  Decades are nowhere near a "very large sample size," so it's not actually 'expected' that the next decade will be below normal, just because the last one was above.  

 

As danstorm said, read my previous post on coin flips (thanks, Dan).  Basically, even if a fair coin is flipped fairly and you see heads 10 or even 100 times in a row, the next flip is still just a 50-50 probability of heads, not way less, as most people would guess.  This is often referred to as the "gambler's fallacy" - gamblers often take small sample size deviations from the mean (like 5 straight blacks in roulette or three straight 7's in craps) and think that the next spin or roll is more likely to not be black or 7, which makes them wrongly bet more - they're wrong and that's why casinos make so much money, lol.  

 

Blackjack, on the other hand, within a give shoe, is not a series of independent events - past history of the shoe can have a major impact on later hands, which is why card counting works - trust me, I've made nice sums counting cards in blackjack.  And in case you're curious, I'm sure my qualifications are as good as dan's.  PhD in chemical eng'g and 25 years in industry designing, running and analyzing experiments and their data.

[UlsterCountySnowZ]

your not supposed to look at the 4k nam for precipitation shield. It's always broken up and always less than what it really is!

If it showed 12" you would

[IsentropicLift]

Web cam from the top of the Washington Monument. Shows flakes flying over DC

 

http://www.earthcam.com/usa/dc/washingtonmonument/?cam=wamo

[Juliancolton]

I think people are reading too far into the WV loops. That baroclinic leaf is making minimal poleward progress, despite what may or may not be going on over the Maritimes. Stranger things have happened, but it just has the wrong "look" for any sort of noteworthy snow event.

[Dino]

Looking at the radar trends, the moderate precip will have a rough time moving north of Maryland.  See red line.