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November 15 Snow/Ice Chance

showmethesnow

By showmethesnow,
in Mid Atlantic

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Bob Chill

Bob Chill

Posted
Posted
15 minutes ago, Chris78 said:

GFS and Cmc both took a step back at 00z unfortunately.

Both are a couple degrees warmer throughout.

Yea, not much room to spare even with the coldest runs and being so early in the cold season is no small feat to overcome. I won't be up but euro will prob add a few degrees here and there. 

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showmethesnow

showmethesnow

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Posted
7 hours ago, high risk said:

         Significant ice storm near the cities?     That's going to be extremely difficult to accomplish given the very warm antecedent ground/road temperatures.

  

Ice storm as in a lot of sleet not so much in the way of freezing rain. That said I do think we will see a decent period of freezing rain in the NW burbs as we lose the temps over head. Possibility of some modest accretions on elevated surfaces through that region and with some of the trees still retaining leafage there is always the chance it could become an issue.

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arlwx

arlwx

Posted
Posted 
URGENT - WINTER WEATHER MESSAGE
National Weather Service Baltimore MD/Washington DC
316 AM EST Wed Nov 14 2018

VAZ025-503-504-508-141630-
/O.CON.KLWX.WS.A.0006.181115T0600Z-181116T0600Z/
Augusta-Western Highland-Eastern Highland-
Central Virginia Blue Ridge-
316 AM EST Wed Nov 14 2018

...WINTER STORM WATCH REMAINS IN EFFECT FROM LATE TONIGHT THROUGH
LATE THURSDAY NIGHT...

* WHAT...Heavy mixed wintry precipitation possible. Total ice
  accumulations of one quarter inch or greater are possible.
  Total snow and sleet accumulation of several inches is also
  possible.

* WHERE...Augusta, Western Highland and Eastern Highland
  Counties, along with the Central Virginia Blue Ridge.

* WHEN...From late Wednesday night through late Thursday night.

* ADDITIONAL DETAILS...Slippery road conditions are possible.
  Scattered power outages and tree damage are possible due to
  the ice. The hazardous conditions could impact the morning and
  evening commutes on Thursday. Any ice accumulation on paved
  surfaces including driveways, sidewalks, and parking lots,
  could also create hazardous conditions for those venturing out
  on foot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$
URGENT - WINTER WEATHER MESSAGE
National Weather Service Baltimore MD/Washington DC
316 AM EST Wed Nov 14 2018

MDZ003-VAZ031-WVZ052-053-141630-
/O.EXA.KLWX.WS.A.0006.181115T0900Z-181116T1100Z/
Washington-Clarke-Berkeley-Jefferson-
316 AM EST Wed Nov 14 2018

...WINTER STORM WATCH IN EFFECT FROM LATE TONIGHT THROUGH LATE
THURSDAY NIGHT...

* WHAT...Heavy mixed wintry precipitation possible. Total ice
  accumulations of one quarter inch or greater are possible.
  Total snow and sleet accumulation of several inches is also
  possible.

* WHERE...Portions of western Maryland, western Virginia and
  eastern West Virginia.

* WHEN...From late Wednesday night through late Thursday night.

* ADDITIONAL DETAILS...Slippery road conditions are possible.
  Scattered power outages and tree damage are possible due to
  the ice. The hazardous conditions could impact the morning and
  evening commutes on Thursday. Any ice accumulation on paved
  surfaces including driveways, sidewalks, and parking lots,
  could also create hazardous conditions for those venturing out
  on foot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.

&&

$$
URGENT - WINTER WEATHER MESSAGE
National Weather Service Baltimore MD/Washington DC
316 AM EST Wed Nov 14 2018

MDZ501-502-VAZ026>030-507-WVZ050-051-055-501>506-141630-
/O.CON.KLWX.WS.A.0006.181115T0900Z-181116T1100Z/
Extreme Western Allegany-Central and Eastern Allegany-Rockingham-
Shenandoah-Frederick VA-Page-Warren-Northern Virginia Blue Ridge-
Hampshire-Morgan-Hardy-Western Grant-Eastern Grant-
Western Mineral-Eastern Mineral-Western Pendleton-
Eastern Pendleton-
316 AM EST Wed Nov 14 2018

...WINTER STORM WATCH REMAINS IN EFFECT FROM LATE TONIGHT THROUGH
LATE THURSDAY NIGHT...

* WHAT...Heavy mixed wintry precipitation possible. Total ice
  accumulations of one quarter inch or greater are possible.
  Total snow and sleet accumulation of several inches is also
  possible.

* WHERE...Portions of western Maryland, western Virginia and
  eastern West Virginia.

* WHEN...From late Wednesday night through late Thursday night.

* ADDITIONAL DETAILS...Slippery road conditions are possible.
  Scattered power outages and tree damage are possible due to
  the ice. The hazardous conditions could impact the morning and
  evening commutes on Thursday. Any ice accumulation on paved
  surfaces including driveways, sidewalks, and parking lots,
  could also create hazardous conditions for those venturing out
  on foot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Watch means there is potential for significant
snow, sleet or ice accumulations that may impact travel. Continue
to monitor the latest forecasts.
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showmethesnow

showmethesnow

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Posted

Probably at a point where we should start paying more attention to the mesos. The latest runs (06Z) of the 12K and 3K NAM have stepped back on the snowmaps with both the 10:1 and the snow-depth seeing decreases. 10:1 is still fun to look at on both models though as we are seeing generally 6+ from the cities on out. The snow-depth charts are somewhat underwhelming compared the the 10:1 as we are seeing a general 1 1/2 to 2 inches from the city on north/west on the 12K and 1/2 to 1 inch for the 3K (Ferrier snowfall for the 3K is showing 1-2 inches). But I am not a big fan of the snow depth charts whatsoever because I find they almost always underplay the ground truth and often enough by a fairly significant amount. Doesn't mean they are wrong in this case, just that you have to take them with caution like with any other snow map

Without delving into the atmospheric temp profile one thing the huge discrepancy in the snow maps tell me is that the NAMs see a lot of ice. In this case probably a lot of sleet though I half expect those around the fall line could experience a somewhat decent freezing rain event mixed in later in the event especially on elevated surfaces. One thing I did notice is that the initial thump on both models was underwhelming. Models have a tendency to under play that aspect of a storm so I would not be surprised that we see more snow out of that feature then currently projected.

 

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showmethesnow

showmethesnow

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Posted

In the last 24 hours of runs I haven't seen the improvements needed at 500 mb with the closed low/shortwave that I felt we needed to get a fresh supply of cold in from the west to help offset the eroding CAD. In fact the look has degraded somewhat. At this point hopes for a flip back to snow of any substance with the wrap around are slipping away except for those possibly on the PA line. So what we get with the initial thump, before switching over to sleet/freezing rain, may very well be it. 

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poolz1

poolz1

Posted
Posted

I think LWX summed it up pretty good in their overnight discussion.  Its a razor thin margin and models will sway 1-2 degrees throughout the column on every run...but in this case 1-2 degrees is the difference between a winter landscape and mud with some crunchy leaves.  IMO, unless things take a very obvious trend today, it will be a nowcast situation. If i envision a bust on the positive side, and speaking mainly for mby,  I would like to see clear calm conditions until about 1am,  WAA precip racing up the shen valley and becoming heavy...snow breaking out by 4-5am and becoming heavy pretty quickly....thump until noon.  Just give me several hours of what looks like deep winter and its a huge win.  Greasing the gears early this season and with the h5 look in the lr, it's going to be a long ride!

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BristowWx

BristowWx

Posted
Posted
2 minutes ago, poolz1 said:

I think LWX summed it up pretty good in their overnight discussion.  Its a razor thin margin and models will sway 1-2 degrees throughout the column on every run...but in this case 1-2 degrees is the difference between a winter landscape and mud with some crunchy leaves.  IMO, unless things take a very obvious trend today, it will be a nowcast situation. If i envision a bust on the positive side, and speaking mainly for mby,  I would like to see clear calm conditions until about 1am,  WAA precip racing up the shen valley and becoming heavy...snow breaking out by 4-5am and becoming heavy pretty quickly....thump until noon.  Just give me several hours of what looks like deep winter and its a huge win.  Greasing the gears early this season and with the h5 look in the lr, it's going to be a long ride!

Agree.  Bottom line is the air mass is just not that cold so even with the other ingredients being in the cake you can’t just delete or reduce one and expect a good cake.  

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showmethesnow

showmethesnow

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Was just looking over the soundings of the latest GFS so this is in reference to that. The biggest problem I am seeing at this point is that we are seeing a deep warm layer just above 850 running through the snow producing regions of the atmosphere. It is a shame really because I think the 850's on down would support a somewhat extended period of snow especially north and west of the metro. It is so marginal at the onset that I question whether DC would even see any snow before it goes straight over to sleet. Of course the warm layer improves the farther north and west you go. But the big takeaway I get is after the initial round of whatever snow falls we are then probably looking at an extended period of sleet for many. Only when you get towards the PA line and western Carroll and/or Fredrick would we probably see an extended period of snow. Maybe 2-4 or 3-5 inch deal. Think those around the metros really need to see the initial thump come in hot and heavy.

eta: Think a one or two degree colder solution within that warm layer would make a world of difference on our snow chances.

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mattie g

mattie g

Posted
Posted
12 minutes ago, BristowWx said:

Agree.  Bottom line is the air mass is just not that cold so even with the other ingredients being in the cake you can’t just delete or reduce one and expect a good cake.  

This airmass is damn cold - can’t get too much colder this time of year - but the calendar is working against us.

Congrats to everyone tracking and pulling for this one, but for all but the very most favored areas this was always a huge uphill climb.

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showmethesnow

showmethesnow

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Posted
3 minutes ago, losetoa6 said:

And I think there's a reasonable chance with models showing heavy rates quickly after initial onset ( wall of snow) . Hrrr I posted shows this potential well . .. albeit its longgg range

I believe that is what will probably occur because the models are notorious at under playing that feature. Can see a quick inch or two for many in the metros before we start losing the snow producing regions.

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H2O

H2O

Posted
Posted

The pollution of snow maps that just show too much white stuff gets everyone going to the higher sides of possible amounts.  Its Nov.  Its anomalous cold air that even gets us the chance of that.  Highs in the low 30s in mid Nov isn't common.  Its still about climo and that more help is needed to get really good snows in Nov.  Some pingers and mangled fatties will be a win for me.  Its a good storm for atmospheric memory for DJF

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showmethesnow

showmethesnow

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Posted
2 minutes ago, osfan24 said:

I thought Ava's map was pretty realistic. Coating to two for most, with the favored areas getting 2-4.

Don't think I have seen it. But it seems reasonable enough with what we are seeing within the models themselves. Such a marginal situation especially in the upper levels that just a little colder solution would probably mean a world of difference on what snow we see. Really no reasoning (except maybe the fact that the models have seemed to have a warm bias so far this fall) but more a feeling, I tend to believe we will see the models trend a touch colder.

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showmethesnow

showmethesnow

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Posted
3 minutes ago, H2O said:

The pollution of snow maps that just show too much white stuff gets everyone going to the higher sides of possible amounts.  Its Nov.  Its anomalous cold air that even gets us the chance of that.  Highs in the low 30s in mid Nov isn't common.  Its still about climo and that more help is needed to get really good snows in Nov.  Some pingers and mangled fatties will be a win for me.  Its a good storm for atmospheric memory for DJF

We were oh so close though. Little better cooperation at 500 mbs and we would have probably seen our snowstorm especially in the burbs.

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