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January Mid-Long Range Disco


WxUSAF

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This post won't be very interesting to the more knowledgable posters here, but I've been trying to get a better understanding of what's going on between the surface and 500mb.  Today's Euro run was a good example, so I thought I'd share while we wait for the 18z globals and ensembles.

At hour 132 on today's Euro run, snow is falling across much of our region. 

We5G9oc.png

The coastal has formed offshore, but the surface winds are from the north. 

7GBQzDP.png

But it is dry to our north.  So where is all the water for the precipitation coming from?  It becomes clear if you look at the midlevels.  The below gif starts at the surface and goes up to 500mb. 

Vz3piwK.gif

If you track the centers of circulation at each level, you can see that there is basically a funnel of circulation extending from the surface low (on the east end) to the 500mb trough (on the west end), with closed circulation at all levels except 500 mb (which is just about to close off).  At 850 mb and 700 mb, there is a clear onshore component to the winds, and at these levels there is high relative humidity over us.  I believe that's where the water is coming from.  The closed low at 500 mb helps establish a more onshore flow in the mid-levels, which is why it gives us bigger storms.  Someone please correct me if I'm wrong!

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11 minutes ago, Bob Chill said:

You don't need to look at a single model to know the bar has been raised on this event. Wes writing an article and Ian popping in is all you need to know. Jeb will start taking appointments soon 

oh well thats different.. If IAN popped in.. im all in..  

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On 12/6/2017 at 1:22 AM, BTRWx's Thanks Giving said:

Whoever thought of last year's SE paste may have been onto something!

ecmwf_acc_snow_noram_96.png

 

On 12/6/2017 at 1:03 PM, Cobalt said:

Eyeballing Euro, it looks slightly better than 0z thru 48 hours

 

On 12/6/2017 at 1:12 PM, stormtracker said:

My clothes are safe.  I'm shocked at this development.  

 

On 12/6/2017 at 1:15 PM, Bob Chill said:

Maybe, but it didn't waver much at all from 0z for areas from NC northward. Back to back runs looking very similar at this lead is a telltale sign most of the time. 

 

On 12/6/2017 at 1:24 PM, osfan24 said:

Right, but when's the last time the Euro didn't give someone a snowstorm and they got blitzed?

 

On 12/7/2017 at 2:19 PM, midatlanticweather said:

Hear European goes zonal in the long range. What is the word? 

 

On 12/7/2017 at 9:24 PM, Cobalt said:

3K NAM further west through hr 31

 

On 12/8/2017 at 1:08 AM, yoda said:

If you want to take the EURO snow map as is... 2" line is just east of the I-81 corridor

 

On 12/8/2017 at 11:22 PM, mattie g said:

#huggers

 

On 12/13/2017 at 2:08 PM, mitchnick said:

 

On 12/16/2017 at 2:04 AM, Cobalt said:

Euro says "too North? How about too South?"

ecmwf_ptype_ma_35.thumb.png.7c5fd84ef628cb3872dee8f5380d6609.png

Rule #37 of being a Snow weenie. You never complain about snow being too far South or too far North on D5+ models. They will answer your request even more so. Want the storm North? Boom, you've got 70 and sun while folks in Michigan complain about mixing problems. Want it farther South? Boom, Atlantic freezes over

 

11 minutes ago, Bob Chill said:

Good thing there's been a pronounced south trend for the last 24 hours. 

Hm tweet to me was pretty discouraging 

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5 minutes ago, Bob Chill said:

Yea, even a little more progressive compared to 12z. 

It's mostly noise but no improvement at all. Gfs is really pushing the cold and gets the front way east of the euro so the low develops too far out to sea. Gfs is also faster with the trough by about 6 hours. Good old fashioned model war. 

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2 minutes ago, leesburg 04 said:

Are we out?

HM thinks it's a northeast storm. Weird given right now the gfs misses us to the southeast not the northeast but he might just be going pure Nina climo and ignoring current NWP. Still time for it to trend to a Boxing Day type miss then hook back into New England. 

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7 minutes ago, psuhoffman said:

HM thinks it's a northeast storm. Weird given right now the gfs misses us to the southeast not the northeast but he might just be going pure Nina climo and ignoring current NWP. Still time for it to trend to a Boxing Day type miss then hook back into New England. 

Mount Holly seems to be favoring a similar outcome based on the 12z suite, but certainly leaves open the possibility of a more Euro-like evolution:

Wed thru Fri...Alberta Clipper moving through the lower Great Lakes
with eventual redevelopment further east, but the tough question
is exactly: where? The latest suite of 12Z/12 operational models
continue to diverge, with little run to run consistency. The GFS
develops low pressure off the NC coast Wed night and moves it
northeast along the northern wall of the Gulf Stream, well south
of the 40N/70W benchmark, into Thursday. The UKMET is similar.

These scenarios would have little impact on our region, with the
storm system remaining well offshore. Meanwhile, the ECMWF is much
further west, developing low pressure east of the Virginia Capes
Wed night, then northward through Cape Cod on Thu. It`s expansive
precip shield on the western side of the system (a bit of a model
bias at times) is also suspect. Nevertheless, this solution has
greater impacts on our region in terms of wintry weather.

The respective ensembles are similar, the GEFS further east and the
EPS further west. But there is a lot of spread noted in the mid-
level height fields of both the GEFS and EPS regarding the placement
of the cutoff low, which translates into uncertainty with the
location of the attendant surface system, e.g., storm track. WPC
favors a blend of the GEFS and EPS ensembles, which places emphasis
on more extensive redevelopment further north and east of our
region, which would limit impacts.
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gfs giving RDU a snowstorm 5-6 days out is fine with me. Last time I was discouraged because the trajectory was all wrong and the gfs was near Bermuda at this range. I'll admit it came back west a little more then I expected but I just felt it was all wrong from this range. The adjustment we need this time is doable. 

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8 minutes ago, psuhoffman said:

HM thinks it's a northeast storm. Weird given right now the gfs misses us to the southeast not the northeast but he might just be going pure Nina climo and ignoring current NWP. Still time for it to trend to a Boxing Day type miss then hook back into New England. 

Book it

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5 minutes ago, psuhoffman said:

HM thinks it's a northeast storm. Weird given right now the gfs misses us to the southeast not the northeast but he might just be going pure Nina climo and ignoring current NWP. Still time for it to trend to a Boxing Day type miss then hook back into New England. 

Given the last 24-48 hours, I don't think anybody has even medium confidence. 2 days ago, it was an easy call for the NE but as leads shorten that idea is all but gone. As least the idea of a straight NS miller b jumping from the lakes to coast. 

Seems like for us we have a 75% chance at a light event (T-3"), 25% chance at a big event, no event, or mixed/rain. That seems like a fair call. 

 

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