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Jan 16/17 light snow event.


clskinsfan

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1 minute ago, wawarriors4 said:

It’s been called a Clipper, or a redeveloper...to me seems almost more like a Manitoba Mauler, if I’m not mistaken, those usually have the best chance to work out for us....but I could be totally wrong

Its not really a mauler as it is picking up moisture from the south because of the orientation of the trough. The NAM has backed off on the early Tuesday start this run. But it looks juicy to the south.

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For anyone who's interested, here's a quick summary of what I saw when digging through the 12z Euro run to figure out where the moisture is coming from.  I'll leave out most of the pictures, but if you want to follow along then you can get the relevant plots at https://weather.us/model-charts/euro.  Unfortunately that site doesn't have a great UI right now, so I find it's easiest to toggle between one tab that shows precip and another tab that shows winds. 

Up to about 69 hours out, you can see from the 700 mb level wind streamlines that the precip appears to be coming from the gulf along the front.  This is the overrunning event.  You can also see that the closed 925 circulation has formed over VA, and an area of enhanced precip is forming on its northern side (where the winds come from the east and northeast)

At around 81 hours, you can see that the circulation at 925 has shifted southeast, taking the enhanced precip with it.  But there is a new area of precipitation near Wilmington, NC that was not there at 00z.  I believe the reason for this is that the trough has shifted at 12z so that the winds at 700-850 mb come onshore, whereas at 00z they ran parallel to the coast.

At around 87 hours, there is ongoing precip near the northern delmarva peninsula that wasn't there at 00z.  This could be due to the shift in the 700 mb winds, but I think it also has to do with the formation of closed circulation at 850 mb that wasn't there at 00z.  This circulation at 850 mb is likely related to the closed H7 contour that Bob pointed out.

Put it all together, and you get the final qpf map.

eH7w6JI.png

The stripe from Augusta, GA through Washington, DC is from the gulf moisture pulled up along the front.

The enhanced precip in central VA is from the circulation at around 925 mb.

The enhanced precip in eastern NC is from the onshore flow from just off the SE coast.

This gives us three ways in which things could get better:

1)  The trough shifts in a way that brings up more moisture from the gulf for the overrunning event.  Of course, the trough could also shift to make things worse.

2)  The 925 mb circulation shifts north (the formation of closed circulation at higher levels could also help).

3)  The upper-level winds near Wilmington turn almost due north to bring moisture from the SE coast to our neck of the woods.  I believe this is one of the reasons why the trough becoming less positive would be a good thing.

As usual, please take this with a grain of salt as I'm just figuring this stuff out.  And if I'm wrong, please let me know.

 

 

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The RGEM ensemble is supportive of a two-part event, with light precip in DC tomorrow and Tuesday.

The high-res RGEM saw no precip tomorrow, unlike the 12z RGEM and 3k NAM.

And fwiw, I think the global ensembles are still useful at this range.  Especially after seeing the EPS.  :weenie:

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Mount Holly's take- not too impressed. An inch or less with a band of light snow showers along the front, with central/northern coastal NJ possibly getting 1-4" IF the Euro idea is correct. Basically they believe any coastal development will be too late, and too far north, and only impact places NE of Philly if it occurs.

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5 minutes ago, MD Snow said:

Both of the Nam's are picking up on the light dusting tomorrow, though. Which I think would be inside their useful range.

18z RGEM has it to.  It will be interesting to see what the 18z high-res RGEM says.  At 12z it said there would be no snow tomorrow.

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1 minute ago, C.A.P.E. said:

Mount Holly's take- not too impressed. An inch or less with a band of light snow showers along the front, with central/northern coastal NJ possibly getting 1-4" IF the Euro idea is correct. Basically they believe any coastal development will be too late, and too far north, and only impact places NE of Philly if it occurs.

And that is probably a good call in all reality. Just with the seasonal trend this year you have to favor east. I definitely was disappointed in the 18Z NAM. It basically shut me out after giving me 2-3 on the previous run. It is a precarious storm for us out here. If the coastal develops we are probably screwed in all honesty.

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