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Super Bowl Slop Storm

Ji

By Ji,
in Mid Atlantic

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usedtobe

usedtobe

Posted
Posted

Beware of using the 850 temp inhopes of seeing snow.  Below I've posted the temp data from the NAM for Sunday at 1PM.  It's a torch between 900 and 950 mb.   That layer rises to above freezing by 10AM with a 950 mb temp of 2.4C and a dewpoint temp of 1.5.  Wee can hope for a nice rain though for western folks it will probably start as freezing raiin or sleet.   

LEV PRES  HGHT  TEMP  DEWP  RH  DD   WETB DIR SPD THETA THE-V THE-W THE-E   W
     mb     m     C     C    %   C     C  deg knt   K     K     K     K    g/kg
-------------------------------------------------------------------------------
SFC 1009    58   2.0   1.2  94  0.8   1.7 165   7 274.5 275.2 274.4 285.7  4.14
  1 1000   130   1.5   1.0  97  0.5   1.3 166  11 274.6 275.3 274.5 285.8  4.12
  2  950   546   4.8   4.4  97  0.4   4.6 188  45 282.1 283.0 280.1 297.3  5.53
  3  900   986   3.8   3.4  97  0.4   3.6 199  55 285.4 286.3 281.6 300.6  5.43
  4  850  1448   0.6   0.2  97  0.4   0.4 206  53 286.8 287.6 281.3 299.8  4.58
  5  800  1933  -1.7  -2.1  97  0.4  -1.9 215  57 289.3 290.0 281.8 301.1  4.10
  6  750  2444  -4.0  -4.4  97  0.4  -4.2 221  57 292.2 292.9 282.6 303.0  3.66
  7  700  2987  -6.1  -6.8  95  0.7  -6.4 228  48 295.7 296.3 283.6 305.5  3.27
  8  650  3564  -8.8  -9.8  92  1.1  -9.2 229  46 299.0 299.5 284.4 307.5  2.78
  9  600  4181 -11.3 -12.7  90  1.3 -11.8 227  50 303.0 303.4 285.5 310.5  2.40
 10  550  4844 -15.4 -17.1  86  1.8 -15.9 231  47 305.9 306.2 285.9 311.7  1.81
 11  500  5556 -20.2 -22.4  82  2.2 -20.7 235  51 308.4 308.7 286.2 312.6  1.27
 12  450  6329 -25.2 -27.8  79  2.5 -25.7 229  60 311.5 311.7 286.9 314.5  0.87
 13  400  7173 -31.6 -34.5  75  2.9 -32.0 232  64 313.9 314.0 287.3 315.7  0.51
 14  350  8102 -39.1 -42.5  70  3.4 -39.4 239  71 316.0 316.1 287.8 316.9  0.26
 15  300  9138 -48.2 -51.7  67  3.5 -48.4 237  77 317.4 317.4 288.0 317.8  0.11
 16  250 10309 -59.1 -62.8  63  3.6 -59.2 237  95 318.1 318.1 288.2 318.3  0.03
 17  200 11694 -59.3 -73.6  14 14.2 -59.5 249  94 338.8 338.8 294.0 338.8  0.01
 18  150 13514 -57.0 -85.0   2 28.0 -57.3 243  76 371.9 371.9 300.9 371.9  0.00
 19  100 16056 -59.6 -87.1   2 27.4 -59.9 246  66 412.6 412.6 306.8 412.6  0.00
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Scraff

Scraff

Posted
Posted
4 minutes ago, ers-wxman1 said:

12z NAM brings the precip in a bit later on Sunday. High is well east by then, any cold air is eroded quickly. Other than a very brief (like a few minutes of frozen at onset), likely to go to rain fast to the east of I-81, likely all rain I-95.

I mean the cars and roads do need a washing. Ground needs a soaking.  I hope it pours for hours. 

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high risk

high risk

Posted
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6 minutes ago, ers-wxman1 said:

12z NAM brings the precip in a bit later on Sunday. High is well east by then, any cold air is eroded quickly. Other than a very brief (like a few minutes of frozen at onset), likely to go to rain fast to the east of I-81, likely all rain I-95.

 

     True, although the 3k NAM maintains (just barely) cold air longer to the west and northwest of DC for quite a bit longer.

 

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Ji

Ji

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8 minutes ago, high risk said:

 

     True, although the 3k NAM maintains (just barely) cold air longer to the west and northwest of DC for quite a bit longer.

 

 

1 minute ago, clskinsfan said:

Pretty astounding differences between the RGEM and NAM at only 48 hours out. The RGEM has been pretty solid so far this year. And the NAM hasnt been awful either. But one of them is going to bust horribly.

the 3K NAM looks nothing like the other NAM

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Buddy1987

Buddy1987

Posted
Posted
18 minutes ago, clskinsfan said:

Pretty astounding differences between the RGEM and NAM at only 48 hours out. The RGEM has been pretty solid so far this year. And the NAM hasnt been awful either. But one of them is going to bust horribly.

Wow, you aren't kidding. RGEM and NAM are worlds apart. Surface on RGEM shows all snow down this way, as it traverses my region from hr 48-54.

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cae

cae

Posted
Posted

The differences between the RGEM and 3k aren't huge if you look at the temps.  RGEM gets precip into the cities more quickly, but the 12z has backed off from the 06z 54-hour RGEM.    I suspect the RGEM's cold bias is a factor here, especially as the 48-54 hour RGEM is at the end of its range.

eta:  Ninja'd by Bob Chill.  I'll add that I'm curious as to what the high-res RGEM shows, as it has less of a cold bias than the RGEM.

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BristowWx

BristowWx

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5 minutes ago, Chris78 said:

Hard to believe everything has trended towards the GFS. Big win for it...lol

Yep.  I would like to think the meso's have some merit in this but GFS has been somewhat deadly.  No reason to doubt it in a marginal setup like this.  

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cae

cae

Posted
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Pivotal weather has maps that show the max column temperature for different models.  They might come in useful for this storm.  He's the 3k NAM at 51 hours, when precip is getting going near the cities.

V09WSwJ.png

At 48 hours the 3k has a pretty good virga storm going.  I think that's one of the main differences between the 06z RGEM and the 3k NAM.  The 06z had more of that precipitation reaching the ground.

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high risk

high risk

Posted
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4 minutes ago, BristowWx said:

Yep.  I would like to think the meso's have some merit in this but GFS has been somewhat deadly.  No reason to doubt it in a marginal setup like this.  

        I don't totally agree.    I'll always trust the GFS for synoptic details, but if there is synoptic agreement, I'll toss the GFS thermal profiles.    This model is notorious for wiping out wedges way too fast, and while the mesos often run cold, they're usually closer to the truth than the GFS.    As noted earlier, this isn't a great setup to lock in cold air (with south winds), but the antecedent air mass is dry, so some in situ CAD is still likely.    Don't get me wrong - I'm not calling for a front end thump of snow or a major ice event, but I do expect a messy mix for a while, especially for those west and northwest of DC. 

 

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mappy

mappy

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5 minutes ago, cae said:

Pivotal weather has maps that show the max column temperature for different models.  They might come in useful for this storm.  He's the 3k NAM at 51 hours, when precip is getting going near the cities.

<snip>

At 48 hours the 3k has a pretty good virga storm going.  I think that's one of the main differences between the 06z RGEM and the 3k NAM.  The 06z had more of that precipitation reaching the ground.

no complaints here... that's got my backyard below 0

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BristowWx

BristowWx

Posted
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4 minutes ago, high risk said:

        I don't totally agree.    I'll always trust the GFS for synoptic details, but if there is synoptic agreement, I'll toss the GFS thermal profiles.    This model is notorious for wiping out wedges way too fast, and while the mesos often run cold, they're usually closer to the truth than the GFS.    As noted earlier, this isn't a great setup to lock in cold air (with south winds), but the antecedent air mass is dry, so some in situ CAD is still likely.    Don't get me wrong - I'm not calling for a front end thump of snow or a major ice event, but I do expect a messy mix for a while, especially for those west and northwest of DC. 

 

Roger and thank you sir.  Hoping for the best or at least something interesting. 

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pasnownut

pasnownut

Posted
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14 minutes ago, Bob Chill said:

I'm impressed with the GFS for sure. I figured it had this one wrong. Nope. Now I'll hug the GFS and promptly get burned down the line. lol

12z GFS (the new King) has ticked a bit colder at 700/850's for Sunday, so while some say were cooked.  I say....not yet.

small differences make a big difference in many of our yards....so thats why I'm saying it.

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Bob Chill

Bob Chill

Posted
Posted
3 minutes ago, WeatherShak said:

I'm curious how much of the GFS's recent success could be contributed to it's computing power upgrade over the past few weeks. 

The physics haven't changed. The GFS has always been good with northern stream dominant winters. After the upgrade (almost 2 years ago now) it seems even better. The euro was "upgraded" too but quite frankly, it seems like a downgrade for our specific purposes. 

The GFS did trend towards a stronger southern low (like the euro) with the 12z run but it's not going to matter. The northern low does all the damage it needs to do by that point. Which the euro has trended towards. So in the end it looks like the GFS and Euro are going to meet somewhat in the middle...but that middle = not much snow in our entire region so it makes the gfs look that much better. lol

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