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Mar 10 - Easter Weekend model/threat discussion thread


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I'm taking the "I'll believe it when I see it" road.

The trend all season has been drier and weaker and I see no reason why any of that would change now.

Too many times we've been fooled into thinking that the pattern would make a major flip into a blocking regime and all Winter it's ended up either being transient or hasn't happened.

Forgive me for being a debbie downer, but it's hard to ignore seasonal trends, especially when climo is becoming increasingly unfavorable each day that passes.

It seems this one will be transient, so we are threading the needle so to speak. It will take a near perfect setup to get snow here post 3/20, but anything is possible I suppose.

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Several quick thoughts:

 

1. The ensemble forecast for the rapid fall in the AO/development of blocking is extreme in magnitude (quite similar to what happened in March 1956).

2. The pattern evolution will very likely feature colder than normal readings through much of the rest of March with some milder days, once it sets in

3. The subtropical jet could become active, especially during the last 10 days of the month.

4. The above ingredients argue for an above climatological risk for accumulating snow during the last 10-15 days of the month.My guess is that cities such as Philadelphia, Newark, New York, and Boston have not seen their last accumulating snow of winter 2014-15. The 12z GFS highlighted some potential, but it's way too soon to try to pin down details other than to note that there remains potential for additional wintry weather. 

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I think most people are still conditioned to treat mid 40s as warm based on last month, so we will manage.

Based on the past week and temps near 60 you'll still hear whining with those temps, add in a good breeze and self destructive sun days, us getting deeper into March and people will be annoyed.

Mornings especially when most will realize they'll have to warm up their cars with temps in the mid 20s.

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Question,

 

If we do we see an anomalous AO drop and the development of blocking wouldn't that increase the likelihood of some type of long duration, large scale impact system, but not necessarily have any bearing on precipitation type?

 

So in other words, wouldn't a significant rainstorm be just as likely in this upcoming pattern as a significant snowstorm?

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Question,

 

If we do we see an anomalous AO drop and the development of blocking wouldn't that increase the likelihood of some type of long duration, large scale impact system, but not necessarily have any bearing on precipitation type?

 

So in other words, wouldn't a significant rainstorm be just as likely in this upcoming pattern as a significant snowstorm?

Yes.

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I count (could be wrong) 3 years in which a snowfall greater than 6 inches fell after March 15th in Central Park... So 6% of years. Of course, one would think the chance of that is elevated this year, but far from a sure thing.   

So statistically what are our chances for a snowfall 6" or greater post March 15?

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Question,

 

If we do we see an anomalous AO drop and the development of blocking wouldn't that increase the likelihood of some type of long duration, large scale impact system, but not necessarily have any bearing on precipitation type?

 

So in other words, wouldn't a significant rainstorm be just as likely in this upcoming pattern as a significant snowstorm?

Definitely. It would depend where things set up.

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Normally, I would agree with the watch and wait idea to see if it was real. That's the approach that makes sense when (ensemble)modeling has said changes out at day 10+. With that being said, this type of look has been seen before on some guidance at times this year, it has never made it inside of day 10, like it is now. 

 

Day 7 12zEPS

 

 

post-4973-0-69120600-1426111754_thumb.pn

 

 

Which, then turns into this at day 10

 

 

post-4973-0-20220900-1426111892_thumb.pn

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Well the 18z GFS has a cutter that tries to pop a miller B but never really does. Lots of rain verbatim.

If the blocking isn't strong enough everything shifts further north, temps end up warmer, and we can forget about frozen.

The 18z gfs is much warmer and further north but it's only one run.

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If the blocking isn't strong enough everything shifts further north, temps end up warmer, and we can forget about frozen.

The 18z gfs is much warmer and further north but it's only one run.

Well this is exactly my point from earlier about low confidence despite a good overall look. One run turns into two and then two into a cycle and before you know it we end up with 40's and an inch of rain like this coming weekend.
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No shortage of extremes going on now.

 

https://twitter.com/philklotzbach/status/575745938058141696

 

Westerly wind event underway strongest in magnitude in the central Pacific since 1997 according to NCEP Reanalysis.

Yep. That's why so many have such high confidence for something to deepen on the EC during that 10 plus day period

There should be a major buckling of the trough during that period and we will finally have a NEG NAO to work with.

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Yep. That's why so many have such high confidence for something to deepen on the EC during that 10 plus day period

There should be a major buckling of the trough during that period and we will finally have a NEG NAO to work with.

 

Yeah, the 12z EPS are hinting at a possible Amarillo/ Delmarva track after day 10 which would work.

 

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what happened in 1994 ?

what happened in 1994 ?

The mean Jan 94 track . SWs traveled under the block from Amarillo to the Delmarva . It would work with the air mass being forecast .

The result in March might work our even better as there would be so much warm air on the southern side w cold air to the N , you could make the argument for deeper LP resulting in a nice baroclinic zone.

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t seems this one will be transient, so we are threading the needle so to speak. It will take a near perfect setup to get snow here post 3/20, but anything is possible I suppose.

I have seen lots of mild Marches, but I have seen my share of March snows over 52 years as well.Not big snows, but decent ones. I have seen significant snow in October, November, and April. I have seen one major blizzard and two significant Aprils snows. Snow at any time in March is not unusual. No one will be shocked by a late March snow. Not here in NJ. Nor would 80 degrees be shocking. I have seen both. But I have seen more snow events than 80 degree ones, IIRC.

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I count (could be wrong) 3 years in which a snowfall greater than 6 inches fell after March 15th in Central Park... So 6% of years. Of course, one would think the chance of that is elevated this year, but far from a sure thing.   

What are the chances for the first two weeks of December? Probably higher, but not by much I would guess, and yet no one is shocked by early December snows.

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I have seen lots of mild Marches, but I have seen my share of March snows over 52 years as well.Not big snows, but decent ones. I have seen significant snow in October, November, and April. I have seen one major blizzard and two significant Aprils snows. Snow at any time in March is not unusual. No one will be shocked by a late March snow. Not here in NJ. Nor would 80 degrees be shocking. I have seen both. But I have seen more snow events than 80 degree ones, IIRC.

 

80s in March are EXCESSIVELY rare in this region, what are you talking about?  An 18" blizzard in the last 5 days of March is likely more probable.

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80s in March are EXCESSIVELY rare in this region, what are you talking about?  An 18" blizzard in the last 5 days of March is likely more probable.

There were 80 degree days in 98, and also 2001? Might have been 70's. It is not shocking. It happens. In March, ANYTHING can happen. have you not heard of this before?

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80s in March are EXCESSIVELY rare in this region, what are you talking about?  An 18" blizzard in the last 5 days of March is likely more probable.

What are the actual stats? I used to be a boater and can remember several 80 degree temps in March. But yes, snow is mmore likely, that was my point.

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crude spag 500mb comp\GFS surface prog

 

stops at 24hrs ref point

66hrs  for Saturdays Rainstorm-GFS surface

 

last stop at 240hrs

 

good luck to our peeps with a snowstorm in mind 

 

***my take***

the op runs will trend bone dry for this period

transitory phenomena  10 days away   

 

 

look how flat and south the estimated prog  is @ 240hrs

 

http://weather.cod.edu/forecast/

 

drier vibe

http://www.esrl.noaa.gov/psd/map/images/ens/prec_f240_us.html

 

you could light a candle for fun....... :arrowhead:

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