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January 6-7 Storm Discussion: we’re due?


WxUSAF
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3 hours ago, high risk said:

     That's fair.    The depth field is underdone in events with warm ground going in, marginal temps, and good rates.     But it's a strong alternative to 10:1 maps when you have a lot of sleet (or other mix) or poor rates with marginal temps.     In events that argue for rates overcoming temps, a blend of the 10:1 and snow depth, with a solid lean towards the depth, often works well.  

That’s all our events lately 

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1 minute ago, Imgoinhungry said:


Hmm. Thats weak. A lot of ice in addition?


.

Yea def.. looked at pivotal .74 for ROA, .71 CHO area.. .30” plus Culpepper and up 81 Harrisonburg etc all smoked with ice totals.

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1 minute ago, Buddy1987 said:

Yea def.. looked at pivotal .74 for ROA, .71 CHO area.. .30” plus Culpepper and up 81 Harrisonburg etc all smoked with ice totals.

This isn’t an ice storm setup.  It’s not like it’s in the teens leading up to this and it’s drizzling for hours.   I’d cut those down significantly.  

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1 minute ago, Eskimo Joe said:

Cool. Now we need a real model to shift towards it.

For Reisterstown

10:1 9”

Kuchera 6.6”

snow depth 1.6”

good luck figuring that out :lol:

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Just now, nj2va said:

This isn’t an ice storm setup.  It’s not like it’s in the teens leading up to this and it’s drizzling for hours.   I’d cut those down significantly.  

Yea but even half is still not good at all. Normally we’re 60 the day before a freezing rain event. It’s been cold today and tomorrow leading into the event. I just feel like it will surprise some.

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This isn’t an ice storm setup.  It’s not like it’s in the teens leading up to this and it’s drizzling for hours.   I’d cut those down significantly.  

Agreed - it’s hovering above freezing. I think
once the 850s are shot, it’s plain rain.

3k does the @psuhoffman thing though around 5/6pm and almost pulls the RA/SN into the Belway again. 3k is the best run I’ve seen in the last day-ish that doesn’t involve fleeing westward to see flakes
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2 minutes ago, NorthArlington101 said:


Agreed - it’s hovering above freezing. I think
once the 850s are shot, it’s plain rain.

3k does the @psuhoffman thing though around 5/6pm and almost pulls the RA/SN into the Belway again. 3k is the best run I’ve seen in the last day-ish that doesn’t involve fleeing westward to see flakes

synoptically, 3k nam and nam had colder 850s leading into event as a result of the confluence being handled significantly differently this run at this lead time starting from only 18 hours out

hopefully this is a trend and something we see on all guidance tonight! nam was pretty close for my liking tho honestly

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1 minute ago, AtlanticWx said:

synoptically, 3k nam and nam had colder 850s leading into event as a result of the confluence being handled significantly differently this run at this lead time starting from only 18 hours out

hopefully this is a trend and something we see on all guidance tonight! nam was pretty close for my liking tho honestly

We're 48 hours from the event. Hope it's getting sampled better and we bust colder regionwide. Give everyone 3" - 5".

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synoptically, 3k nam and nam had colder 850s leading into event as a result of the confluence being handled significantly differently this run at this lead time starting from only 18 hours out
hopefully this is a trend and something we see on all guidance tonight! nam was pretty close for my liking tho honestly

Toggling it back and forth — that is a pretty significant bulge downward. Thanks for pointing that out
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1 minute ago, Eskimo Joe said:

We're 48 hours from the event. Hope it's getting sampled better and we bust colder regionwide. Give everyone 3" - 5".

i do wonder if it got sampled, the confluence is over an area that isn't like data dead anymore

regardless, hopefully we see these changes continue! wishing for a colder outcome for everyone 

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1 hour ago, Warm Nose said:

Prob belongs in Banter, but I can suggest several spaces:

  • NAMd
  • Sun Angle
  • Will I be OK to drive to [insert place]
  • App Runner
  • Outlier ... Toss
  • [...] Pummeled! (will also accept Short Pump)
  • Snow hole

Fringed, tucked

53 minutes ago, Eskimo Joe said:

Winter Storm Watch extended to Carroll County.

We had a chat, I let them know  

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The NAM 10:1 maps look huge even along the I-95 corridor, because even after the precip type maps show rain, the model microphysics are generating sleet which is going into the snow water equivalent tally..   Here is a sounding from the "rain" area:

 

image.thumb.png.ce3629adb8c579533e40175967458622.png

 

   That's heavy sleet.   Not saying that the thermal profile will be correct, but it explains the generous 10:1 totals.

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2 minutes ago, SnowenOutThere said:

The 3k Nam does the @psuhoffman way to victory and keeps the 850s considerably cooler during that critical 3 hour window, just a tick or two more and even the immediate suburbs would be on the snowy side. 

 

trend-nam4km-2024010500-f047.850th.us_ma.gif

That’s a really cool map. You can see the wind barbs feel the effect of the northerly component to the cad. What I would give to have some of the air with the dews up north of VT/NH/ME

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6 minutes ago, AtlanticWx said:

i do wonder if it got sampled, the confluence is over an area that isn't like data dead anymore

regardless, hopefully we see these changes continue! wishing for a colder outcome for everyone 

RAOB data is only incorporated into 00z/12z. 

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2 minutes ago, high risk said:

 

The NAM 10:1 maps look huge even along the I-95 corridor, because even after the precip type maps show rain, the model microphysics are generating sleet which is going into the snow water equivalent tally..   Here is a sounding from the "rain" area:

 

image.thumb.png.ce3629adb8c579533e40175967458622.png

 

   That's heavy sleet.   Not saying that the thermal profile will be correct, but it explains the generous 10:1 totals.

I think most east of the fall line would take sleet on snow over rain though. NAM is most likely full of crap. But that is probably an acceptable outcome for most. 

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The reasoning for the shift in the colder solution on the NAM is the development of a closed 850mb low tracking south of the Potomac over north-central VA. Pay close attention to the wind barb across the northwest area and how the 850mb southeasterlies hit a brick wall over Parrs Ridge and the wind direction flips. This would allow for cold air to advect into the northern and western side of the circulation creating a more beneficial PBL and keep everything frozen, or even all snow. Check out the wind barbs to the east of RNK...

702073097_850mbNestHeights.thumb.PNG.d0b882a55011c05af6a003d70ae4d480.PNG

 

As a result, watch the 850mb temp profile as we work through time. This is actually how you get surprises and periods of heavy snow when you weren't expecting. 

floop-nam4km-2024010500.850th.us_ma.thumb.gif.6b9f1626f5eff1c4ff3c8decf3a00ab5.gif

 

MAJOR CAVEAT.... THIS IS JUST ONE RUN OF ONE MODEL!!!

We are going to want to see other guidance pull this off and have it become something to watch. This could be a one run and done deal, but there is potential for this. I will not be committing anything until I see some agreement from other guidance. It was interesting to see and point out as a possibility. It would affect the forecast in a big way. These are why these marginal events are so tricky. One thing can make or break a forecast. Let's hope it's right. Right now, no changes from my current thinking. 

 

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