Midweek Threat of Snow?

By: Zachary Labe , 8:30 PM GMT on December 04, 2011

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Current teleconnections do not support an east coast snowstorm. The record breaking Arctic Oscillation has reached nearly +5.4 which is record highly anomaly for the month of December. The NAO is also very high and corresponds to limited blocking across the north Atlantic. The current jet stream flow is very transient and therefore limits the potential for east coast nor'easters. In fact the threat of east coast snow is diminished by nearly 50% or more in a +AO and +NAO regime.

"Current NAO and PNA Predictions"

(Courtesy of NOAA)

In this unfavorable regime, snow can still be possible in near ideal setups. Current GFS guidance has been supporting the concept for a southern stream system moving along the Middle Atlantic coast and up along the eastern seaboard. The energy is ejected from the southwest. The PV will be displaced across the Hudson Bay, which will help to funnel the cold air south along the east coast. Current GFS prognostics suggest a low pressure developing in the southeast along the remnants of the washed-out cold front. Cold air will be lacking, but H85s will generally be at or below 0C from the Mason-Dixon line on northward and generally west of I-95.

Typically in a La Nina, the southern stream remains very weak and therefore limits the potential for southern storm systems such as this possibility. But given the series of waves moving along the front, this is certainly possible.

Model guidance remains at odds with this possibility... The ECMWF supports a relatively similar H5 prognostic, but instead holds back the S/W energy and allows for a flatter wave traversing across the central Middle Atlantic. Although recent antecedent runs have generally become more amplified. The GFS remains most amplified with a 996mb coastal runner spreading heavy snow northwest of I-95 in a very Nina-like snow/rain line setup. Other guidance such as the UKMET is generally a middle ground run between the ECMWF and GFS, while the GGEM remains even flatter heading straight out to the sea. Many GFS ensembles support a storm system in this period with remarkable consistency in the 12z run with the GEFS mean supporting the OP GFS.


12z GFS 12/04/2011 run...

The GFS run as posted above is about as perfect as a storm system can look for snow lovers in this dreaded teleconnection nightmare. Current model accuracy verification charts for days 3-6 remain very poor for both the GFS and ECMWF. But it is important to note the consistency in the GFS ensembles supporting an amplified wave in this period.

With weak blocking, it is very simple for this shortwave to take a simpler approach as a flat wave off the east coast, but there is definitely the possibility for this storm system to take a GFS-like track with inland snow.

I still am not quite sure what will happen given this setup. I actually remain a bit on the optimistic side of the forecast for snow lovers for locations northwest of I-95. I can definitely see how this wave becomes amplified enough for a similar solution and given the remarkable ensemble consistency, I believe this period needs to be monitored. Given the lack of boundary layer cold air, it is likely this will not be a snow threat for I-95 south of New England. I will have a new blog Tuesday morning...

"Local Harrisburg Radar"

(Courtesy of WGAL)

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83. MariettaMoon
1:58 PM GMT on December 06, 2011
Quoting Sockets:


How is it looking further north for the Portsmouth, NH area?


Very track dependent for you, partially because you're so close to the coast. You could see up to 8" if axis right over you, but could quickly be 1" if axis just barely to your northwest.
Member Since: June 11, 2011 Posts: 36 Comments: 677
82. MariettaMoon
1:53 PM GMT on December 06, 2011
Quoting PhillySnow:
Hurray! That would be sweet. Looking forward to the new blog, Blizz.


That was just the 18Z NAM. I think a quick burst of 1" in Philadelphia more likely before sunrise Thursday. You have a slightly better chance of that being just west of Philly. A steady increase in accums heading northwest.

In my mind, I'm going with this for now...

Poconos: 4"-8"
Lehigh Valley: 3"-6"
LSV: 2"-5"
Philly far northwest burbs: 2"-4"
Philly immediate burbs: 1"-2"
Philadelphia: 1"

Done and gone by sunrise Thursday.
Member Since: June 11, 2011 Posts: 36 Comments: 677
81. originalLT
1:31 PM GMT on December 06, 2011
Locals finally mentioning this morning of the possibility of some snow here on Thurs., but they are saying "wet snow" with little or no accumulation. LT Stamford CT.
Member Since: January 31, 2009 Posts: 0 Comments: 8010
80. PhillySnow
12:19 PM GMT on December 06, 2011
Quoting MariettaMoon:
The 18Z NAM looks sweeeet. A general 6"-8" bullseye inland (very locally 10") with even 3"-5" for Philly.
Hurray! That would be sweet. Looking forward to the new blog, Blizz.
Member Since: December 18, 2009 Posts: 0 Comments: 1273
79. Zachary Labe
12:07 PM GMT on December 06, 2011
Looking good LSV! New blog within a few hours or so.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
78. PalmyraPunishment
10:49 AM GMT on December 06, 2011
CTP is discussing WSW for later and the local on-air "meteorologists" in town here haven't even so much as discussed the possibility of anything more than "possibly changing over to a period of wet snow".

I know you don't want to be an alarmist or cry "wolf", but how is this not irresponsible on their behalf?
Member Since: January 31, 2007 Posts: 9 Comments: 2250
77. listenerVT
4:54 AM GMT on December 06, 2011
Quoting MariettaMoon:
The 18Z NAM looks sweeeet. A general 6"-8" bullseye inland (very locally 10") with even 3"-5" for Philly.

12Z ECMFW probably similar amounts placed a little farther southeast than the 18Z NAM.

GFS may be well out to lunch with up to a trace of snowfall up I-95 and nothing anywhere else. Maybe those new updates to the GFS are actually screwing it up.


Is this what you're referring to?
http://www.hpc.ncep.noaa.gov/qpf/qpfloop.html


Got link?
Member Since: July 11, 2007 Posts: 0 Comments: 5597
76. weatherman321
3:15 AM GMT on December 06, 2011
well looks like we here in western PA will have to wait for the next one.... hopefully it comes at least before new years !!
Member Since: August 23, 2008 Posts: 0 Comments: 140
75. GTOSnow
2:58 AM GMT on December 06, 2011
Local area guys are still saying a dusting to 2" in the higher elevations of the Worcester Hills and rain elsewhere. I am hoping we get some decent snow out of this! No more trees to fall on my car at least....
Member Since: February 10, 2010 Posts: 0 Comments: 235
74. Sockets
2:15 AM GMT on December 06, 2011
Quoting MariettaMoon:
The 18Z NAM looks sweeeet. A general 6"-8" bullseye inland (very locally 10") with even 3"-5" for Philly.

12Z ECMFW probably similar amounts placed a little farther southeast than the 18Z NAM.

GFS may be well out to lunch with up to a trace of snowfall up I-95 and nothing anywhere else. Maybe those new updates to the GFS are actually screwing it up.


How is it looking further north for the Portsmouth, NH area?
Member Since: August 11, 2007 Posts: 0 Comments: 97
73. MariettaMoon
1:56 AM GMT on December 06, 2011
The 18Z NAM looks sweeeet. A general 6"-8" bullseye inland (very locally 10") with even 3"-5" for Philly.

12Z ECMFW probably similar amounts placed a little farther southeast than the 18Z NAM.

GFS may be well out to lunch with up to a trace of snowfall up I-95 and nothing anywhere else. Maybe those new updates to the GFS are actually screwing it up.
Member Since: June 11, 2011 Posts: 36 Comments: 677
72. MariettaMoon
1:32 AM GMT on December 06, 2011
Quoting TheRasberryPatch:
Blizz - thanks for the updates. when you say high QPF does that mean snow to water ratio more like 12:1? October was terrible I think I was not even 6:1


Nah, it's just quantitative precipitation forecast. Just total precipitation amounts, snow to water ratios aren't related.
Member Since: June 11, 2011 Posts: 36 Comments: 677
71. listenerVT
11:59 PM GMT on December 05, 2011
It hung at 52 for a long while today. But it sure looks like we're in for a temperature drop this week.

So, what's the likelihood of accumulating snow here on Friday? A beloved friend, who was like a mother to me, and was nearly 98 years wise, died last night; and her family is flying and driving in from all over. The service and burial commence Friday at 10am....brrr!

Hoping everyone's travels go safely.

Member Since: July 11, 2007 Posts: 0 Comments: 5597
70. TheRasberryPatch
11:53 PM GMT on December 05, 2011
Blizz - thanks for the updates. when you say high QPF does that mean snow to water ratio more like 12:1? October was terrible I think I was not even 6:1
Member Since: January 26, 2007 Posts: 72 Comments: 6276
69. weathergeek5
11:44 PM GMT on December 05, 2011
I am here however I have end of semester projects due plus finals.
Member Since: December 25, 2005 Posts: 0 Comments: 1744
68. wxgeek723
11:27 PM GMT on December 05, 2011
Any chance Philly could see a glimpse of white from this? Even if it's just for 5 minutes and mixed with rain?
Member Since: August 28, 2008 Posts: 79 Comments: 3714
67. LivelySnow
11:19 PM GMT on December 05, 2011
Quoting Blizzard92:
Where is everyone? We have a snowstorm to track. 12z ECMWF has best snows for Harrisburg up through New England just northwest of I-95.


I'm here! I'm here!!! LOL!!! Just looked at your blog today by chance and ...wahoo!!!!! I'm praying for this one! I love snow....but in December...it's a dream come true! Great job as always...can't wait to see what you have to say tomorrow!!! :)
Member Since: January 29, 2011 Posts: 0 Comments: 53
66. Zachary Labe
11:02 PM GMT on December 05, 2011
bwi- All of the NWS offices are being conservative which is typical and probably the right move. If this system doesn't waffle too much from current ideas, lows probably will drop to around 33F for you with rain/snow and possible light accumulations.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
65. bwi
10:56 PM GMT on December 05, 2011
DCA looks like we might get some white melty spits on Wednesday night. But with a low of 36, it won't stick! But I think it's time to put winter tires on anyways.

Wednesday: Rain. High near 50. North wind between 7 and 10 mph. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.

Wednesday Night: Rain before midnight, then rain and snow likely. Low around 36. North wind between 5 and 7 mph. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

Thursday: Mostly sunny, with a high near 46.

A POSITIVELY TILTED UPPER-LEVEL TROUGH WILL REMAIN WELL TO OUR WEST
TUESDAY NIGHT. THE SOUTHERN BRANCH OF THIS SYSTEM IS EXPECTED TO
CUTOFF INTO AN UPPER-LEVEL LOW WEDNESDAY BEFORE MOVING THROUGH OUR
REGION LATE WEDNESDAY AND WEDNESDAY NIGHT. THIS SYSTEM WILL CONTINUE
TO SPREAD PRECIPITATION ACROSS OUR AREA AT THE SAME TIME COLDER AIR
WILL BE MOVING IN FROM THE NORTH AND WEST. THERE WILL LIKELY BE
ENOUGH COLD AIR FOR PRECIPITATION TO END AS A PERIOD OF SNOW MAINLY
FROM WASHINGTON/BALTIMORE TO THE NORTH AND WEST. THE BEST CHANCE
FOR ACCUMULATING SNOW WILL LIKELY BE ACROSS THE FAR NORTHERN AND
WESTERN SUBURBS OF WASHINGTON/BALTIMORE INTO THE SHENANDOAH VALLEY
AND POTOMAC HIGHLANDS. WINTER WEATHER HEADLINES MAY BE WARRANTED
ACROSS THESE AREAS.-- End Changed Discussion --

Member Since: September 4, 2007 Posts: 0 Comments: 1407
64. Zachary Labe
10:50 PM GMT on December 05, 2011
Quoting MariettaMoon:


That's my feeling as well, although not near as strong as the October storm, and not affecting northern New England. It's almost definate that this low will track south of the Mason-Dixon. Question is how fast can the cold air come in for southern areas as most of it could fall as rain the closer you get towards the track. Also, exactly how much QPF.

For eastern PA, I'm getting a feeling like this...

Lehigh Valley & southern Poconos: 3"-6" (All Snow)
LSV: 1"-4" (Rain to Snow)
I-95: C"-1" (Rain, ending as some Snow)

Sharp cutoff in accumulations immediately northwest of the LSV & southern Poconos.

I know it's too early, but what do you think? More, less, farther north, farther south?

I am anxious to see the 0z and 6z runs tonight, but I am thinking a decent plowable snow for the LSV with perhaps the cutoff a tad more northwest. If this comes in Wednesday night, temperatures should be warm enough for snow in the LSV.

hurigo- Thanks! I would do anything to be at the beach currently!
Member Since: December 14, 2007 Posts: 285 Comments: 15140
63. hurigo
10:43 PM GMT on December 05, 2011
Thank you, Blizz, for giving me an assignment. Eager to please you with this report: 56 in Duck and 60 in the beach called VA, but there was a disclaimer by NOAA that the water temps might very easily be wrong! I can tell you that it has been a mild day and I have not been to the ocean for many weeks but the rivers weather has been wUnderful and the skies b e a u t i f u l.
Member Since: October 9, 2005 Posts: 100 Comments: 6744
62. MariettaMoon
10:35 PM GMT on December 05, 2011
Quoting Blizzard92:
I still like my idea of a similar snow axis placement as the October snow.


That's my feeling as well, although not near as strong as the October storm, and not affecting northern New England. It's almost definate that this low will track south of the Mason-Dixon. Question is how fast can the cold air come in for southern areas as most of it could fall as rain the closer you get towards the track. Also, exactly how much QPF.

For eastern PA, I'm getting a feeling like this...

Lehigh Valley & southern Poconos: 3"-6" (All Snow)
LSV: 1"-4" (Rain to Snow)
I-95: C"-1" (Rain, ending as some Snow)

Sharp cutoff in accumulations immediately northwest of the LSV & southern Poconos.

I know it's too early, but what do you think? More, less, farther north, farther south?
Member Since: June 11, 2011 Posts: 36 Comments: 677
61. Zachary Labe
10:26 PM GMT on December 05, 2011
Quoting hurigo:


hmmmmmmm...... got something new you're working on? have you found the solution to the snow forecast?

PS how you doing? Things going well in school?

I have been better, lol. We basically have a two week study session for finals up here under a 22 hour silence period. This means the only time for noise is between 6-8pm each day. People are a little bit up tight here when it comes to studying to say the least, lol.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
60. Zachary Labe
10:23 PM GMT on December 05, 2011
Quoting weatherman321:
blizz what the estimation for western PA ?

I do not think this system comes back far enough western Pennsylvania, although given the strength of the southeast ridge, we cannot rule it out completely but it is unlikely.

hurigo- lol, no not this time. Hope all is well! Any idea what the water temperatures down there are still?
Member Since: December 14, 2007 Posts: 285 Comments: 15140
59. hurigo
10:21 PM GMT on December 05, 2011
Quoting Blizzard92:
*New blog tomorrow morning!


hmmmmmmm...... got something new you're working on? have you found the solution to the snow forecast?

PS how you doing? Things going well in school?
Member Since: October 9, 2005 Posts: 100 Comments: 6744
58. hurigo
10:20 PM GMT on December 05, 2011
Hey Blizz, et al.
So no snow for me on the VA/NC border?
Member Since: October 9, 2005 Posts: 100 Comments: 6744
57. weatherman321
10:16 PM GMT on December 05, 2011
blizz what the estimation for western PA ?
Member Since: August 23, 2008 Posts: 0 Comments: 140
56. Zachary Labe
10:15 PM GMT on December 05, 2011
*New blog tomorrow morning!
Member Since: December 14, 2007 Posts: 285 Comments: 15140
55. Zachary Labe
10:14 PM GMT on December 05, 2011
This will definitely be a wet snow starting late Wednesday night through Thursday. It is a quick mover, but high QPF is possible in some areas.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
54. shipweather
9:58 PM GMT on December 05, 2011
I'm hoping we don't get that nasty snow again. What's the timeline?

Thanks!
Member Since: December 15, 2007 Posts: 19 Comments: 987
53. NEwxguy
9:46 PM GMT on December 05, 2011
their saying rain changing to snow up here in Southern New England,need some colder air to keep this snow,but this isn't panning out like I thought it might.
Member Since: September 6, 2007 Posts: 888 Comments: 15989
52. wunderstorm87
9:33 PM GMT on December 05, 2011
One glimmer of hope from CTP's discussion for us snow lovers...
ONE CAVEAT...WITH SUCH LOW
CONFIDENCE...THIS SYSTEM AND QPF AMOUNTS /AS WELL AS THE GENERAL
IMPACT OVERALL/ COULD POSS BE GREATER THAN CURRENTLY PREDICTED.
DEPENDING ON THE OUTCOME...THERE MAY BE ENOUGH COLD AIR IN PLACE
TO PRODUCE SNOW ACCUMULATIONS.

The 0z model cycle should give us a better idea of what's going on.
Member Since: August 5, 2010 Posts: 0 Comments: 588
51. wunderstorm87
9:13 PM GMT on December 05, 2011
It looks like the 12z ECMWF is now on board and gives us around an inch of snow. CTP's new forecast for my area (updated about 15 minutes ago) has a 30% chance of all rain before 1am, then a chance of rain and snow after 1am. This storm doesn't look nearly as promising as the October one.
Member Since: August 5, 2010 Posts: 0 Comments: 588
50. PhillySnow
9:09 PM GMT on December 05, 2011
Not MIA, Blizz - I've been checking the forecast and the blog every few hours hoping the storm will track colder for us. NWS now has us with a mix of rain and snow Wed. night to Thursday morning.

My sister-in-law's in Nashville and she just told me they went from 70 degree weather to around 40 in a matter of hours today. There's hope!
Member Since: December 18, 2009 Posts: 0 Comments: 1273
49. weatherman321
9:07 PM GMT on December 05, 2011
NWS removed snow chances for western PA in last update for wed night and thursday
Member Since: August 23, 2008 Posts: 0 Comments: 140
48. PalmyraPunishment
9:06 PM GMT on December 05, 2011
In the meantime, I'll man the control.

Tonight's topic: Aliens and why I'm not going to say "It's Aliens..."

buttttttttttt...

It's Aliens.
Member Since: January 31, 2007 Posts: 9 Comments: 2250
47. originalLT
8:52 PM GMT on December 05, 2011
OK guys, let him study!
Member Since: January 31, 2009 Posts: 0 Comments: 8010
46. Zachary Labe
8:50 PM GMT on December 05, 2011
I'll get to people's questions later. Trying to study at the library, lol. 18z NAM is a 7-11in snow for the Lower Susquehanna Valley, haha
Member Since: December 14, 2007 Posts: 285 Comments: 15140
45. TheRasberryPatch
8:31 PM GMT on December 05, 2011
I have been really busy lately, especially this weekend. And the weather has been really good for being outside.

Thanks for the new blog Blizz.

WU forecast has been back and forth with snow vs. sunny conditions. I see they have forecast somewhat cold conditions for the weekend. I say somewhat because the highs are average for winter.

If we get snow, I hope it isn't wet and heavy like the last snow in October. That snow was so wet. Your gloves were soaked in minutes.
Member Since: January 26, 2007 Posts: 72 Comments: 6276
44. Mason803
8:24 PM GMT on December 05, 2011
LWX starting to believe:

THERE WILL LIKELY BE
ENOUGH COLD AIR FOR PRECIPITATION TO END AS A PERIOD OF SNOW MAINLY
FROM WASHINGTON/BALTIMORE TO THE NORTH AND WEST. THE BEST CHANCE
FOR ACCUMULATING SNOW WILL LIKELY BE ACROSS THE FAR NORTHERN AND
WESTERN SUBURBS OF WASHINGTON/BALTIMORE INTO THE SHENANDOAH VALLEY
AND POTOMAC HIGHLANDS. WINTER WEATHER HEADLINES MAY BE WARRANTED
ACROSS THESE AREAS.-- End Changed Discussion --

Member Since: November 5, 2008 Posts: 0 Comments: 1139
43. HeavySnow
8:06 PM GMT on December 05, 2011
Hey Blizz, check out the Cap Weather Gang's write-up of my snow chances. I'd provide a link but I know you see it on FB. I likey what the met Wes says.
Member Since: July 7, 2004 Posts: 18 Comments: 2990
42. Sockets
8:03 PM GMT on December 05, 2011
Blizz, is this storm looking like its going to go north enough to give the Kittery area accumulating snow?
Member Since: August 11, 2007 Posts: 0 Comments: 97
41. Zachary Labe
8:03 PM GMT on December 05, 2011
Quoting shipweather:
NWS seems to say rain for us. I can't understand, unless this is going to be mud snow again.

CTP is hanging quiet today with no update to the long term discussion.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
40. GTOSnow
7:51 PM GMT on December 05, 2011
Local Mets up here in the Worc area are saying we don't have to worry about it as it is going to slide out of here south of us.
Member Since: February 10, 2010 Posts: 0 Comments: 235
39. shipweather
7:29 PM GMT on December 05, 2011
NWS seems to say rain for us. I can't understand, unless this is going to be mud snow again.
Member Since: December 15, 2007 Posts: 19 Comments: 987
38. cicadaknot
7:20 PM GMT on December 05, 2011
12Z ECMWF also farther NW than the GFS with parts of the I95 corridor getting in the action.
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37. weatherman321
7:18 PM GMT on December 05, 2011
00z 06z and 18z NAM has the rain snow line further in with snow reaching into western PA and a little of Eastern OH.. Blizz what is your thought? do we here in Western PA stand a fair chance?
Member Since: August 23, 2008 Posts: 0 Comments: 140
36. Zachary Labe
7:11 PM GMT on December 05, 2011
I still like my idea of a similar snow axis placement as the October snow.
Member Since: December 14, 2007 Posts: 285 Comments: 15140
35. HeavySnow
7:00 PM GMT on December 05, 2011
Present. But so dang warm. Almost 60.
Member Since: July 7, 2004 Posts: 18 Comments: 2990
34. Drakoen
6:59 PM GMT on December 05, 2011
Quoting Blizzard92:
12z GEFS mean is northwest of OP GFS. I would ignore the 12z GFS southeast solution.


I agree. The GFS sliding the low almost into the West Atlantic ridge that has been so prominent does not make sense. In fact the 500mb maps favor a low placement a bit more to the northwest. It make more sense for the system to buckle further northwest up and just east of the apps. The GEFS and the 12z ECMWF have a more reasonable solution
Member Since: October 28, 2006 Posts: 57 Comments: 30832
33. originalLT
6:50 PM GMT on December 05, 2011
Blizz, I think PP is right, it's just hard to believe, but then again it did happen Oct. 29th! Right now by me it's 55F with broken clouds, very light winds from the South, and the Baro. is 30.26 and falling slowly.
Member Since: January 31, 2009 Posts: 0 Comments: 8010

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