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wdrag

HIGH IMPACT Stormy Christmas (EVE and morning) 12/24-25/20 6P-10A

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Topic Edit 508AM: Added HIGH IMPACT and the time back in to the topic and extended 4 hours.  Strongest winds in NJ/ne PA/se NYS roughly 10PM-4A,  NYC/se NYS 1A-6A, LI/CT 2A-to possibly as late as 9A/25 e tip of LI. Minimum wind gust on LI 55 MPH with max 75MPH, NYC-se NYS minimum wind 50 MPH isolated max 70 MPH.  Please follow NWS on all warnings/statements. I'll leave it yourselves to add graphics etc as need be. I'll begin an OBS-NOWCAST thread by 6A. Have not looked at soundings but everything else discussed in yesterdays 518AM topic edit below including HSLC SVR's continues.  We may reach within 2F of the record 66F-2015 max temp for Christmas Day at CP. Flooding of some of the larger rivers, if it is to occur, may be delayed 24 hours or more after after the rain quits Christmas morning,  Max rainfall axis in our forum looks to me to be CT, isolated 4", not including snowmelt runoff.  If anything is missed, please let me know.  Thank you.

Topic Edit 518AM Wednesday 12/23: No significant changes.  The prime threat period might by 2 hours too fast but not enough evidence to change the primary initialization period of weather related issues. My assessment tells me to prepare, without science, for many many thousands without power starting 9PM to midnight Christmas Eve evening, and then across se NYS, LI, CT, MA beginning midnight to 6AM Christmas morning. Gusts NYC airports should be 45-55kt, with potential for isolated 65KT LI/CT/MA.  I expect SVR's for the HSLC lines of heavy showers to help focus the primary short-fuse threats.  Lower chance of any damage northeast PA but ridges there will be most vulnerable there to ~ 55 MPH gusts.  There is limited science on power outage wind damage with leaved trees, without, softer unfrozen ground versus frozen but I don't have this information nor any private services predictive algorithms.  I still think that wind damage will prevail as the most important aspect of this storm, but please follow NWS flood watches, warnings as issued, due to the combined snowmelt and new widespread NYC subforum rainfall of 1-2", with isolated 4" potential inland-most of this in a 9 hour period during Thursday night, Any snow on the backside is exceedingly minor on the I84 high terrain. There actually might be a little better chance for a slight coating of snow Christmas night with the weakening trough aloft passage. 

---

Topic edit at 526AM Tuesday the 22nd: Changed the title to WILL be accompanied by damaging wind LI, and restricted the period of accumulative snow to the interior. I think the wind damage potential is the largest threat from this rapidly deepening 980s surface low moving northward up the front into NYS predawn Christmas. SVR's possible (in my mind likely, even if no lightning) for High Shear Low Cape (HSLC) heavy showers.The Richardson (R)#/wind profile combo on the NAM and even GFS tells me 45kt+ gusts all the major airports in NYC sometime between 10P/24 and 5A/25 . This is further supported by multiple models 80KT+ 850MB winds over LI, in some cases around 90-95kt. From my looking at R# and wind grab, this has the most favorable potential in my past 3 months of examining to realize downward transfer 50-65KT from the lowest 25 to 50 MB of the boundary layer. Whether an isothermal sounding in the lowest part of the boundary layer, or even a slightly inverted sounding can diminish-mute the potential, I don't know. What I do think, is that a lot of folks could wake up with lights out Christmas morning across LI, and possibly NJ/CT.  Flooding potential to me looks the same as it did yesterday-previous days, all a matter of qpf, snowmelt combo to prompt a few rivers into minor or eventually moderate flood stage, even as temps plummet from 60ish near midnight Christmas morning, to near freezing by ~ Noon Friday. Please follow NWS closely on flood potential-they have more tools than I. Snowfall, accumulation less than 1 inch probably restricted in our forum counties only I84 high terrain northwestward. I'll copy this to the last page of this topic and add a couple of wind profiles there.  The future posts will look at FOUS BL winds, which I think will exceed 34kt at LGA and BOS around 06z and 12z/25 respectively. IF not, then I'm a little too severe on my wind expectations.  Also, I'll be adding shorter term wind gust potential graphics, especially Wednesday onward.  (corrected many typos 826A)

--- Below from the origination date of Friday evening the 18th. 

This topic is started primarily because of the recent operational model cycles at one time or another offering a more than ordinary 12-18 hour period of weather here near  Christmas, on top of melting snow.  Always uncertainty. 

Uncertainties abound, including how far inland can a couple of hours of 60 degree temperatures penetrate to melt the snowpack, and will there be any hazardous snow accumulation closer than the hilly western and northern suburbs?  Add to that, is there an inversion thats prevent excessive low level winds from reaching the ground.?

Snowpack will be melting a bit the next few days,, til a sudden brief surge of 60 degree warmth Thursday evening or very early Friday morning, associated with a strong cold front. That front is embedded within a high amplitude trough. It's slowed by a strong 1030-35MB high anchored near the Maritimes, and there is potential for northward moving low pressure along the front, as it traverses across the NYC forum.

Max rainfall should be concentrated just inland (se or sse surface wind) and combined with remaining snow, may? be enough to promote some small stream flooding?  Flooding will be dependent on how much snow melts on the 24th/early 25th combining with around 1" to possibly 2" of rain, prior to the sharp cool down to near freezing by midday the 25th.  Current 12/18 river response models to multiple ensembles are not alarmed at this point so I don't want to make this look worse than it will be. 

Of greater concern is the ECMWF cyclic offering of 60+ MPH gusts to LI (50 inland) which may cause some damage.  Recent experience with the storm of the 16th-17th suggests to me, that we will need at least 60 MPH gusts to see significant damage along the coasts and ridges. It's possible - IF the 850MB southerly jet can exceed 75 knots, preferably 85 knots.  The 18z/18 GFS has 80 knots for e LI and the 12z/18 EC has near 100 knots for all of LI. IF the ECMWF were to verify, it would be lights out for many and not a pleasant Christmas morning. Timing of the event probably sometime at night (6P/24-6A/25 EST)

Snow: Backside snow doesn't often accumulate significantly with temperatures falling rapidly from the 60s to near freezing. Thinking best chance I84 corridor high terrain sometime Friday morning the 25th. 

Graphics: 1) 12z/18 EC 850 wind. EC surface gusts, GEFS chance of 60 MPH wind gusts early Christmas and finally, the WPC qpf forecast from ~18z/18. 608P/18

Screen_Shot_2020-12-18_at_4_32.34_PM.png

Screen Shot 2020-12-18 at 4.12.31 PM.png

Screen Shot 2020-12-18 at 4.25.37 PM.png

Screen Shot 2020-12-18 at 4.22.36 PM.png

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Topic: not quite as robust this morning but no changes.

The good news: If this less robust solution prevails,  power will continue. 

There are diverse model solutions and so am riding this out as proposed yesterday. The 00z-06z/19 cycle might indicate a slightly slower onset-end?

The EC moved its 70 MPH gusts to CC, but still has 75-85 KT 850 jet for e LI Friday morning, increasing to 90-100 kt for Cape Cod.  So the 70 MPH could eventually come back west, if modeling eventually reverts to yesterdays 12z/18 solution. The 06z/19 GFS op is right there with the EC for LI at 850 MB.  So I won't dismiss the topic as invalid, at least not till there is consistent modeling that says... only an ordinary storm. 

MMEFS suggests one or 2 rivers in NJ may flood but for now, nothing widespread major, based on snowmelt and ensembled qpf.

Tail end snow on Christmas: still possible.  Wish all a good day. Walt

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1 hour ago, North and West said:

They said there'll be snow at Christmas
They said there'll be peace on earth
But instead it just kept on raining


.

Well done N & W. You could easily insert it as a stanza/refrain in the song ‘Where Are You Christmas’. As always ...

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Yes, from 

I Believe In Father Christmas

Emerson Lake and Palmer

And also from the late Dan Fogelberg's Same Auld Lang Syne

Second line

The snow was falling Christmas Eve

 

and the last two lines

And as I turned to make my way back home, the snow turned into rain

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3 hours ago, STORMANLI said:

Yes, from 

I Believe In Father Christmas

Emerson Lake and Palmer

And also from the late Dan Fogelberg's Same Auld Lang Syne

Second line

The snow was falling Christmas Eve

 

and the last two lines

And as I turned to make my way back home, the snow turned into rain

wait wasn't there a New Years Eve song just like that too?

 

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Met my old lover in the grocery store
The snow was falling Christmas Eve
I stole behind her in the frozen foods
And I touched her on the sleeve
She didn't recognize the face at first
But then her eyes flew open wide
She went to hug me and she spilled her purse
And we laughed until we cried
We took her groceries to the checkout stand
The food was totaled up and bagged
We stood there lost in our embarrassment
As the conversation dragged
Went to have ourselves a drink or two
But couldn't find an open bar
We bought a six-pack at the liquor store
And we drank it in her car
We drank a toast to innocence
We drank a toast to now
And tried to reach beyond the emptiness
But neither one knew how
She said she'd married her an architect
Who kept her warm and safe and dry
She would have liked to say she loved the man
But she didn't like to lie
I said the years had been a friend to her
And that her eyes were still as blue
But in those eyes I wasn't sure if I
Saw doubt or gratitude
She said she saw me in the record stores
And that I must be doing well
I said the audience was heavenly
But the traveling was hell
We drank a toast to innocence
We drank a toast to now
And tried to reach beyond the emptiness
But neither one knew how
We drank a toast to innocence
We drank a toast to time
Reliving in our eloquence
Another 'auld lang syne'
The beer was empty and our tongues were tired
And running out of things to say
She gave a kiss to me as I got out
And I watched her drive away
Just for a moment I was back at school
And felt that old familiar pain
And as I turned to make my way back home
The snow turned into rain
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19 minutes ago, HeadInTheClouds said:

Because todays music sucks. 

I have three sons.  They know the words to all my fav 80's songs...Their friends come over...they like those songs too..  it surprised me to hear them say today's music sucks. 

 

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1 hour ago, LibertyBell said:
Met my old lover in the grocery store
The snow was falling Christmas Eve
I stole behind her in the frozen foods
And I touched her on the sleeve
She didn't recognize the face at first
But then her eyes flew open wide
She went to hug me and she spilled her purse
And we laughed until we cried
We took her groceries to the checkout stand
The food was totaled up and bagged
We stood there lost in our embarrassment
As the conversation dragged
Went to have ourselves a drink or two
But couldn't find an open bar
We bought a six-pack at the liquor store
And we drank it in her car
We drank a toast to innocence
We drank a toast to now
And tried to reach beyond the emptiness
But neither one knew how
She said she'd married her an architect
Who kept her warm and safe and dry
She would have liked to say she loved the man
But she didn't like to lie
I said the years had been a friend to her
And that her eyes were still as blue
But in those eyes I wasn't sure if I
Saw doubt or gratitude
She said she saw me in the record stores
And that I must be doing well
I said the audience was heavenly
But the traveling was hell
We drank a toast to innocence
We drank a toast to now
And tried to reach beyond the emptiness
But neither one knew how
We drank a toast to innocence
We drank a toast to time
Reliving in our eloquence
Another 'auld lang syne'
The beer was empty and our tongues were tired
And running out of things to say
She gave a kiss to me as I got out
And I watched her drive away
Just for a moment I was back at school
And felt that old familiar pain
And as I turned to make my way back home
The snow turned into rain

A very difficult but necessary song to listen to if your alone this time of year. As always .......

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17 minutes ago, Kborne said:

I have three sons.  They know the words to all my fav 80's songs...Their friends come over...they like those songs too..  it surprised me to hear them say today's music sucks. 

 

Your kids are smart. I grew up with The Beatles, Led Zeppelin, Pink Floyd, The Stones, the Who, Peter Frampton, Van Halen, etc... Todays music just doesn't compare. 

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19 minutes ago, HeadInTheClouds said:

Your kids are smart. I grew up with The Beatles, Led Zeppelin, Pink Floyd, The Stones, the Who, Peter Frampton, Van Halen, etc... Todays music just doesn't compare. 

For some reason this made me think of "The Day The Music Died"
How sadly appropriate!

That's in keeping with the mood of Auld Lang Syne too, as is Don Macclean's other great work,  "Vincent."

On a more positive note and speaking of the 80s, Queen was one of my favorite groups from back then, some of their music was truly operatic.

The Live Aid concert in 1985 was one of my best memories from grade school.  Queen's performance was also duplicated very well in the movie Bohemian Rhapsody.

 

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2 hours ago, Kborne said:

I have three sons.  They know the words to all my fav 80's songs...Their friends come over...they like those songs too..  it surprised me to hear them say today's music sucks. 

 

Growing up in the 70's and college in the early 80's I had to endure the horrible disco era when it appeared rock was slowly being suffocated.

By 1973 the groups I had loved as a little kid (The Beatles, Stones, Zeppelin, Beach Boys, The Who) pretty much everyone head in the clouds mentioned and then some, were breaking up or burning out. By 1975 we needed new blood and groups started to emerge to carry the torch.

I remember in 1975 when I heard Born to Run for the first time, I thought there might be hope on the horizon. AC/DC emerged, lost their lead singer, but got another just as good. Skynrd kept getting better and better, then crashed (literally, tragically). Aerosmith kept it going but there was always the breakups and the drugs.

By the late 70's Bruce gained a following then exploded, Boston was promising but couldn't get past that first album, Heart and the Wilson sisters rocked, a little later Tom Petty & THB exploded. Punk  bands like The Ramones, The Clash, Patti Smith, and Blondie started to get mainstream play, with the exception of the Ramones who never really got their total due.  It's nice that at least the Rock and Roll Hall of fame inducted them in 2002 during their first year of eligibility, but Joey was already  dead by then and Dee Dee and Johnny would soon follow.

U2 started getting airplay in 1981 and Def Leppard, Van Halen, John Cougar, RUN DMC,  Prince and others soon followed. The Stones, The Who, Bowie, Queen, Stevie Winwood started putting out new material again that got airplay, and more importantly MTV play (during the era when they actually played music) and by 1982 Disco was dead.

Thank God almighty and thank you to all the bands that refused to let rock die.

Rock is dead they say, long live rock

Long live rock, I need it every night
Long live rock, come on and join the line
Long live rock, be it dead or alive

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Good Sunday morning everyone, Dec 20. The windshield wipering of the models continues back and forth but there is more consensus.  There is no doubt that we have a pretty good storm coming, that may be lights out for some on Christmas, and where did the water come from along a few rivers and streams, even in still snow clogged street drainage basins of the interior. 

Topic: back to the more robust initial discussion this morning with minor adjustments.  Timing varies from the faster locked in GFS to the EC op that has been wipering a bit, and slower. Duration of the occasionally heavy rain may extend now up to 18 hours.  Therefore, WPC's 1.5" qpf now covers all of the NYC subforum and there is a modeled option  maybe spot 4" in some of the interior higher terrain, if duration of the heavy rain swath is indeed closer to 18 hours. 

00z-06z/20 op model consensus now has 75-85 KT 850 jet for Thursday night-Friday morning (EPS/GEFS clearly 55 kt or greater).  So the 70 MPH gusts could affect a small part of LI with a more general 50-65MPH expected elsewhere along the I95 corridor and possibly a few ridges of the interior,though my confidence on this ridge gust occurrence is lower than NYC, NJ and CT coasts. 

MMEFS suggests a number of rivers may approach action stage or go into flood so I suspect this will eventually need a flood watch as we draw closer to the 24th, and of course dependent on the updated qpf. Follow NWS statements on this. 

Tail end snow on Christmas: still possible, especially hilly regions near I84.  

Have added the 00z/20 GEFS chance of 60 MPH gusts at 06z/25. 606A/20

Screen_Shot_2020-12-20_at_5_01.42_AM.png

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Walt, great thread as usual. As I posted in the other thread, the new parallel GFS v16 did much better than the current OP v15 with the major winter storm this week. It didn’t have the cold and suppressed bias that has been a problem in the current OP. So it’s not a surprise that the v16 is warmer and slower than the current OP for the major storm around Christmas. 
 

New parallel v16 GFS

E15D00FB-2089-4A9D-9CA1-B5A28C031C9B.thumb.png.5abdef13f4f52ded9107775a7b2f72a5.png
 

Current V15 OP

2F68FF47-274F-4265-8FA5-8AF8D5B03C93.thumb.png.5219dd4ffe3c0f4cf8f8529de7ce0e05.png

 

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2 hours ago, bluewave said:

Walt, great thread as usual. As I posted in the other thread, the new parallel GFS v16 did much better than the current OP v15 with the major winter storm this week. It didn’t have the cold and suppressed bias that has been a problem in the current OP. So it’s not a surprise that the v16 is warmer and slower than the current OP for the major storm around Christmas. 
 

New parallel v16 GFS

E15D00FB-2089-4A9D-9CA1-B5A28C031C9B.thumb.png.5abdef13f4f52ded9107775a7b2f72a5.png
 

Current V15 OP

2F68FF47-274F-4265-8FA5-8AF8D5B03C93.thumb.png.5219dd4ffe3c0f4cf8f8529de7ce0e05.png

 

12z GFS is in a hurry... and weaker than previous few cycles and not accepting GFS parallel as the solution. Not buying 12z/20 GFS. Upper air features w ATLC and near 80W were 00z/06z ensembled strong. I'm waiting this out til tomorrow morning 00z-06z/21 cycles.  I expect the GGEM EC and UK will be a bit slower and stronger than the 12z/20 GFS. I agree w general perception the GFS P is better than the current V15 version, but I know not always.  I suspect on two or three cases, the Parallel V16 will do better than the current V15 version on separated trough s of 40N... handling amplification and slowing better. Just a gut feeling.  This one is not that.  Gotta run.

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Good Monday morning everyone, Dec 21- The first day of astronomical winter!  This topic remains (somehow) on target!  

I am 70% confident of damaging wind and power outages part of our forum area within about 3 hours midnight Christmas eve-morning, gusts possibly to 65 or 70 MPH on LI in a HSLC (High Shear Low Cape) band of convection (thunder may not occur but I suspect SVR's may need to be issued or some sort of wind warning).  Did not add the widespread 50 MPH ECMWF gust graphic... suffice it to say, it's been consistent on 50+ for our forum... just cyclically varying it's tracking 70+ between se MA and LI. 

Flooding: Please follow NWS statements on this situation when they are issued. I've added a couple of graphics that show river concerns *yellow* = action consideration and then various color scales for subsequent flood POTENTIAL.  This is qpf based so snow melt will also need to be considered as an addition. Snowmelt doesn't happen all at once: It happens faster in high dew point wind driven air overriding the snow pack, and the rain at first is absorbed by the snow then starts it's melting and release. So, nothing is automatic, guaranteed, instant. I didn't take a look at the individual gaged streams to see the graphing of rainfall and river stage plumes. The point: flooding potential exists.  I'm not sure if it can happen on more than 3 or 4 rivers in our forum area (delayed river flood response may be til the 25th morning) and then much colder temps may lock in some of the runoff.  Widespread 1-2" is expected in 9 hours, with potential for narrow bands of 3-4" in the interior preferred upslope areas...maybe this time CT?  6A/21

 

Screen_Shot_2020-12-21_at_5_02.24_AM.png

Screen_Shot_2020-12-21_at_5_02.37_AM.png

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2 hours ago, wdrag said:

Good Monday morning everyone, Dec 21- The first day of astronomical winter!  This topic remains (somehow) on target!  

I am 70% confident of damaging wind and power outages part of our forum area within about 3 hours midnight Christmas eve-morning, gusts possibly to 65 or 70 MPH on LI in a HSLC (High Shear Low Cape) band of convection (thunder may not occur but I suspect SVR's may need to be issued or some sort of wind warning).  Did not add the widespread 50 MPH ECMWF gust graphic... suffice it to say, it's been consistent on 50+ for our forum... just cyclically varying it's tracking 70+ between se MA and LI. 

Flooding: Please follow NWS statements on this situation when they are issued. I've added a couple of graphics that show river concerns *yellow* = action consideration and then various color scales for subsequent flood POTENTIAL.  This is qpf based so snow melt will also need to be considered as an addition. Snowmelt doesn't happen all at once: It happens faster in high dew point wind driven air overriding the snow pack, and the rain at first is absorbed by the snow then starts it's melting and release. So, nothing is automatic, guaranteed, instant. I didn't take a look at the individual gaged streams to see the graphing of rainfall and river stage plumes. The point: flooding potential exists.  I'm not sure if it can happen on more than 3 or 4 rivers in our forum area (delayed river flood response may be til the 25th morning) and then much colder temps may lock in some of the runoff.  Widespread 1-2" is expected in 9 hours, with potential for narrow bands of 3-4" in the interior preferred upslope areas...maybe this time CT?  6A/21

 

Screen_Shot_2020-12-21_at_5_02.24_AM.png

Screen_Shot_2020-12-21_at_5_02.37_AM.png

Upton mentioned the flooding potential too. @bluewave has been on this for a week. Posters such as @JoshSnow and @jfklganyc owe him an apology. 
 

good work as always Walt, thank you

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12 minutes ago, JoshSnow said:

I’m sorry Chris I’m still learning here. So take my forecast with a grain of salt. 

I’m down to around 4 inches of snow on the ground. Temperatures are going to be above freezing until that rain arrives with the possible exception of tuesday night.

I’m not particularly worried about a rapid melt or clogged sewers. Ground saturation is always an issue.

This isnt a 1/12/96 scenario for the NYC metro or nearby burbs

 

 

 

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16 minutes ago, jfklganyc said:

I’m down to around 4 inches of snow on the ground. Temperatures are going to be above freezing until that rain arrives with the possible exception of tuesday night.

I’m not particularly worried about a rapid melt or clogged sewers. Ground saturation is always an issue.

This isnt a 1/12/96 scenario for the NYC metro or nearby burbs

 

 

 

There isn't going to massive flooding here but watch out in Binghamton.

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2 minutes ago, JoshSnow said:

Binghamton will most likely rain for an hour and than turn to heavy snow so I’m not sure how Binghamton will get any flooding from this!

the ratios there were high too-so 40 inches of snow but with a lower water content

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1 hour ago, jfklganyc said:

I’m down to around 4 inches of snow on the ground. Temperatures are going to be above freezing until that rain arrives with the possible exception of tuesday night.

I’m not particularly worried about a rapid melt or clogged sewers. Ground saturation is always an issue.

This isnt a 1/12/96 scenario for the NYC metro or nearby burbs

 

 

 

what about downstream rivers and creeks getting flooded because of massive melting upstream?

 

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1 hour ago, LibertyBell said:

what about downstream rivers and creeks getting flooded because of massive melting upstream?

 

I think I mentioned this earlier, but please please please clear out storm drains and downspouts. I spent a small part of the weekend trying to explain gravity and the physics of hydrology to my neighbors. Maybe putting it like that makes me sounds like an assclown. ¯\_(ツ)_/¯

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