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1/25-1/27 Mauler Thread #2


DDweatherman

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Cobb output from the 6z suite

NAM: 5.8" with .33" PL @ BWI.

9.7" with .13" PL @ DCA

6.1" @ Westminster

13.7" @ IAD

GFS: 3.9" @BWI

.8" @ DCA with the rest coming in the form of rain. Total QPF was over .5"

8.2" @ Westminster

1.7" @ IAD

lots of bust potential the further south you are with this.

Thanks for posting this, now I don't have to go look

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Thanks...yeah...I'm assuming I can get in front of it as the coastal doesn't hit up there until later right?

Late tonight into tomorrow its just lighter stuff with the clipper, but most of that is during the day tomorrow up that way. The coastal storm impact begins tomorrow night.

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I was just reading Justin Berk's newest post on his site. Since, he likes to note the Canadian model when forecasting storms, there are pictures of a very rainy model run of the RGEM included in this post. I don't know if that's a newer model run or not. Did the newest run of the RGEM follow suit with the rain it forecasted yesterday or up snow totals from the last run?

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I was just reading Justin Berk's newest post on his site. Since, he likes to note the Canadian model when forecasting storms, there are pictures of a very rainy model run of the RGEM included in this post. I don't know if that's a newer model run or not. Did the newest run of the RGEM follow suit with the rain it forecasted yesterday or up snow totals from the last run?

Oh that is definitely from the newest run.  There are significant temperature issues with the storm.. 

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I was just reading Justin Berk's newest post on his site. Since, he likes to note the Canadian model when forecasting storms, there are pictures of a very rainy model run of the RGEM included in this post. I don't know if that's a newer model run or not. Did the newest run of the RGEM follow suit with the rain it forecasted yesterday or up snow totals from the last run?

I'm afraid so...http://www.tropicaltidbits.com/analysis/models/?model=rgem&region=us&pkg=mslp_pcpn_frzn&runtime=2015012506&fh=48&xpos=0&ypos=317  :facepalm:

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Is it 'cause we torch today?

 

No not necessarily.. right now the current obs are much colder than what the models had depicted last night.  I think we definitely have temps on our side.  Besides a storm like this will manufacture its own cold air.  

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The temp issue is ironic because of why it's happening. When we started getting greedy and rooting for a neg tilt to the trough we (or at least I) didn't think about what types of issues it could cause. When things looked good for a light to moderate event, the slp track was through n ky-s va-off the coast. Nice and simple. Intact slp tracking south of us = easy cold air.

 

Because the vort has dug so deep and the trough goes neutral/neg, the primary low loses progression over wva and stalls it until the coastal gets going. This puts a wrench in our cold air advection because with the primary doing that we don't get rid of return (sw) flow until the coastal takes over and the primary fizzles. The good runs all had slp progressing south of us with closed circulation.

 

That all changed yesterday. Now we deal with temps and precip at the same time. Typical mid atlantic "no mans land" in between good stuff to the west and good stuff to the east. It's a very complicated process that happens at our latitude. There is room for both a surprise or a big wtf. As stated earlier in this thread, there are 2 events to watch. How intact and far south and east the primary gets before stalling and getting absorbed will play a large role in how much precip falls after the surface gets cold enough.

 

N MD and the winchester crew are obviously in the best place. PSU made a great post about the potential for localized banding with the inverted trough. NAM, RGEM, GFS and Euro all have the signal for it to be possible to get enhanced banded n/s oriented precip falling in the region. Whether it happens or not or where it happens will become close to a nowcast.

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The temp issue is ironic because of why it's happening. When we started getting greedy and rooting for a neg tilt to the trough we (or at least I) didn't think about what types of issues it could cause. When things looked good for a light to moderate event, the slp track was through n ky-s va-off the coast. Nice and simple. Intact slp tracking south of us = easy cold air.

 

Because the vort has dug so deep and the trough goes neutral/neg, the primary low loses progression over wva and stalls it until the coastal gets going. This puts a wrench in our cold air advection because with the primary doing that we don't get rid of return (sw) flow until the coastal takes over and the primary fizzles. The good runs all had slp progressing south of us with closed circulation.

 

That all changed yesterday. Now we deal with temps and precip at the same time. Typical mid atlantic "no mans land" in between good stuff to the west and good stuff to the east. It's a very complicated process that happens at our latitude. There is room for both a surprise or a big wtf. As stated earlier in this thread, there are 2 events to watch. How intact and far south and east the primary gets before stalling and getting absorbed will play a large role in how much precip falls after the surface gets cold enough.

 

N MD and the winchester crew are obviously in the best place. PSU made a great post about the potential for localized banding with the inverted trough. NAM, RGEM, GFS and Euro all have the signal for it to be possible to get enhanced banded n/s oriented precip falling in the region. Whether it happens or not or where it happens will become close to a nowcast.

WHAT IS AN INVERTED TROUGH?

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The temp issue is ironic because of why it's happening. When we started getting greedy and rooting for a neg tilt to the trough we (or at least I) didn't think about what types of issues it could cause. When things looked good for a light to moderate event, the slp track was through n ky-s va-off the coast. Nice and simple. Intact slp tracking south of us = easy cold air.

 

Because the vort has dug so deep and the trough goes neutral/neg, the primary low loses progression over wva and stalls it until the coastal gets going. This puts a wrench in our cold air advection because with the primary doing that we don't get rid of return (sw) flow until the coastal takes over and the primary fizzles. The good runs all had slp progressing south of us with closed circulation.

 

That all changed yesterday. Now we deal with temps and precip at the same time. Typical mid atlantic "no mans land" in between good stuff to the west and good stuff to the east. It's a very complicated process that happens at our latitude. There is room for both a surprise or a big wtf. As stated earlier in this thread, there are 2 events to watch. How intact and far south and east the primary gets before stalling and getting absorbed will play a large role in how much precip falls after the surface gets cold enough.

 

N MD and the winchester crew are obviously in the best place. PSU made a great post about the potential for localized banding with the inverted trough. NAM, RGEM, GFS and Euro all have the signal for it to be possible to get enhanced banded n/s oriented precip falling in the region. Whether it happens or not or where it happens will become close to a nowcast.

something inside keeps nagging me not to give up and that the models still don't have it right yet

of course, today being the 15 year anniversary of a not too dissimilar situation makes me pause some more

 

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My forecast said it would be sunny in DC this morning but instead it is cloudy. Not sure if that will play a role in temps later today but I will take anything.

The upper atmosphere is still cold so the surface should cool and support snow pretty quickly once precip starts. Think some of the models are overdoing the warmth.

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The temp issue is ironic because of why it's happening. When we started getting greedy and rooting for a neg tilt to the trough we (or at least I) didn't think about what types of issues it could cause. When things looked good for a light to moderate event, the slp track was through n ky-s va-off the coast. Nice and simple. Intact slp tracking south of us = easy cold air.

 

Because the vort has dug so deep and the trough goes neutral/neg, the primary low loses progression over wva and stalls it until the coastal gets going. This puts a wrench in our cold air advection because with the primary doing that we don't get rid of return (sw) flow until the coastal takes over and the primary fizzles. The good runs all had slp progressing south of us with closed circulation.

 

That all changed yesterday. Now we deal with temps and precip at the same time. Typical mid atlantic "no mans land" in between good stuff to the west and good stuff to the east. It's a very complicated process that happens at our latitude. There is room for both a surprise or a big wtf. As stated earlier in this thread, there are 2 events to watch. How intact and far south and east the primary gets before stalling and getting absorbed will play a large role in how much precip falls after the surface gets cold enough.

 

N MD and the winchester crew are obviously in the best place. PSU made a great post about the potential for localized banding with the inverted trough. NAM, RGEM, GFS and Euro all have the signal for it to be possible to get enhanced banded n/s oriented precip falling in the region. Whether it happens or not or where it happens will become close to a nowcast.

Excellent explanation, that about wraps it up

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My forecast said it would be sunny in DC this morning but instead it is cloudy. Not sure if that will play a role in temps later today but I will take anything.

The upper atmosphere is still cold so the surface should cool and support snow pretty quickly once precip starts. Think some of the models are overdoing the warmth.

hmmm....

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WHAT IS AN INVERTED TROUGH?

 

This is hr 42 of the 6z gefs. The trough is going negative (another way to think of negative is nw/se orientation of the isobars. The curved yellow streak over our area indicates energy and lift that could produce banded precip. If you don't know how to read a 500mb vorticity chart then you should spend a lot of time reading and learning about. Most important model chart to know and understand. 

 

post-2035-0-69588300-1422194167_thumb.jp

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what I am hoping for is that 1034 high north ofMaine grows a pair and slows down the coastals northward progression long enough to let the storm amplify close to the Delmarva.

Yeah I think there is definitely something to be said for that.  It would only take a little tiny shift to the west to get the MA in to HECs zone.

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