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2013 Mid-Atlantic Severe General Discussion

Kmlwx

By Kmlwx,
in Mid Atlantic

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Ian

Ian

Posted
Posted

yeah i could just bring it with me.  some of it's stuff people should already know but these guys who live out there tend to learn the signals for good days and what to look for on them and whatnot.  im still trying to perfect my sounding knowledge and he talks about that a lot.

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Ian

Ian

Posted
Posted

Does a below normal spring wrt temps help/hurt/make no difference as to the severe season?  I would think the presence of so much cold air would create an environment that would benefit severe weather, but I don't know very much about it.  So .........

 

hard to say. i think ultimately it can help tho it's undoubtedly hurting so far. last year the svr weather season in much of the country was abridged because of the quick warm up in the spring.. so we had a lot of activity already at this point then it shut off for the most part after mid-April. 

 

my guess for now is that April will have a big outbreak or two across the south/midwest etc. the Plains will also probably have a better year than last year... tho those are pretty much WAGs. one concern is that we flip from cold back to a pattern dominated by the drought which could in theory totally fook over the season. but usually having the cold air and good snowpack to the north is helpful overall...

 

around here... prob harder to guess. we tend to get storms every year to some degree no matter what, usually not terribly severe. the drought can help give us those ingredients needed for a big event like the derecho.. just have to see how it plays out.

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Ian

Ian

Posted
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OK, explain that.  Is it just the clashing air masses that make that an appealing setup?

 

a low pushing into the lakes is usually decent for the proper turning with height needed for tornado potential.  anything that cuts west really if it's strong enough.. plus there is just the fact that you pump dew points to near 60 then hit them with a cold front so you get convection with it. the profile is OK but not that good. it's early season so there is no cape barely. plus subsequent runs lost it mostly.

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Ellinwood

Ellinwood

Posted
Posted

a low pushing into the lakes is usually decent for the proper turning with height needed for tornado potential.  anything that cuts west really if it's strong enough.. plus there is just the fact that you pump dew points to near 60 then hit them with a cold front so you get convection with it. the profile is OK but not that good. it's early season so there is no cape barely. plus subsequent runs lost it mostly.

Lows over the Lakes help pull in more southern air, but it's a bit of a give/take around here. The farther north the low is, the less tornado potential we have as surface winds are typically more out of the SW/WSW versus the S/SSE that we want. Also, without the low close by, we usually don't get as good of lapse rates as the upper-level trough and accompanying cooler temps aloft stay to our north as well.

When we want a good tornado setup, I typically look for something similar to the D+10 you posted but also has a good vort max. to the south of it that triggers a secondary low development along the cold front. Our region really needs that secondary low to form up over the mountains or just west of us to help back the winds locally, giving us a more southerly or even easterly component. This was a key factor in the June 1 outbreak last year.

post-96-0-85623700-1364397126_thumb.gif

The thing that held back the instability last year was the late intensification of the primary low over the OH Valley, which didn't have enough time to lift the warm front northward and allow skies to clear before the storm development. (Though one could argue that we needed the warm front for more backing at the surface)

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Ian

Ian

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Yeah, true on the secondary. I actually mentioned that then deleted it for some reason.  I'm not sure it's necessary but it helps.  April 2011 didn't have one.

 

http://www.meteo.psu.edu/~fxg1/NARR/2011/us0427.php

 

But college park did at least to some degree:

 

http://www.meteo.psu.edu/~fxg1/NARR/2001/us0924.php

 

La Plata doesn't appear to:

 

http://www.meteo.psu.edu/~fxg1/NARR/2002/us0428.php

 

They all had solid 500 energy passing in or near the Lakes.

 

Verbatim that 18z 'threat' is pretty lame given the jet but it was still something for so early even if it's gone.

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Bob Chill

Bob Chill

Posted
Posted

Aren't storms from waa in front of ohv lows tpyically benign overall? Not always of course but usually? I've never been that impressed with bands of storms on sw flow like unless they train and dump lots of water. Winds are usually so-so and lightning isn't very intense either. I know there can be shear and rotation but never seems all that exciting. But I'm a no nothing noob so I may know nothing.

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andyhb

andyhb

Posted
Posted

Later on in late Spring/Summer when instability is plentiful, more westerly to west-northwesterly flow aloft events tend to do well in this region. One example is the August 6th, 1993 tornado outbreak in Virginia.

 

080618.png

 

Another would be the June 23rd, 1944 event in WV (Shinnston tornado).

yg2ypIV.gif

 

A good example of the former, more classic setup that Ellinwood describes is the May 2nd, 1929 event (Rye Cove, VA tornado)

qHTfvcd.gif

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Ian

Ian

Posted
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I just went back to the June 1, 2012 reports and found this... anyone besides the NWS see this video?

1837 3 NW COUNTRYSIDE MONTGOMERY MD 3908 7745 VERY BRIEF EF0 TORNADO CONFIRMED BY VIDEO. (LWX)

 

this was one of them but im not sure if it's the same one.

 

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Ian

Ian

Posted
Posted

Aren't storms from waa in front of ohv lows tpyically benign overall? Not always of course but usually? I've never been that impressed with bands of storms on sw flow like unless they train and dump lots of water. Winds are usually so-so and lightning isn't very intense either. I know there can be shear and rotation but never seems all that exciting. But I'm a no nothing noob so I may know nothing.

 

probably.. you'd be looking more at the warm sector/sfc trough/cold front passage in that type of situation.

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Ellinwood

Ellinwood

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Posted

Yeah, true on the secondary. I actually mentioned that then deleted it for some reason.  I'm not sure it's necessary but it helps.  April 2011 didn't have one.

 

http://www.meteo.psu.edu/~fxg1/NARR/2011/us0427.php

 

But college park did at least to some degree:

 

http://www.meteo.psu.edu/~fxg1/NARR/2001/us0924.php

 

La Plata doesn't appear to:

 

http://www.meteo.psu.edu/~fxg1/NARR/2002/us0428.php

 

They all had solid 500 energy passing in or near the Lakes.

 

Verbatim that 18z 'threat' is pretty lame given the jet but it was still something for so early even if it's gone.

Agreed that a secondary isn't necessary, but it can be and often is a huge boost in the potential if it's there.

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WinterWxLuvr

WinterWxLuvr

Posted
Posted

Later on in late Spring/Summer when instability is plentiful, more westerly to west-northwesterly flow aloft events tend to do well in this region. One example is the August 6th, 1993 tornado outbreak in Virginia.

080618.png

Another would be the June 23rd, 1944 event in WV (Shinnston tornado).

yg2ypIV.gif

A good example of the former, more classic setup that Ellinwood describes is the May 2nd, 1929 event (Rye Cove, VA tornado)

qHTfvcd.gif

I'm amazed that anyone on this board would know about the Rye Cove tornado. I grew up hearing about that tornado. They are pretty rare that far west in Va.

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Ian

Ian

Posted
Posted

I don't really think we'll see anything this week but we might.. thunder at least seems a better chance. GFS pulls 60+ dp well north.. forcing lags a bit though. Far enough out it might be able to shift more interesting.

 

post-1615-0-66328700-1365269116_thumb.pn

 

 

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Ellinwood

Ellinwood

Posted
Posted

I don't really think we'll see anything this week but we might.. thunder at least seems a better chance. GFS pulls 60+ dp well north.. forcing lags a bit though. Far enough out it might be able to shift more interesting.

If things are looking stormy and the timing's right either here or south in VA/NC I'll be chasing. Not getting my hopes up for it, but I'll be ready for it if the threat materializes. This time of year a trip to NC seems most likely out of any location in the region.

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Ellinwood

Ellinwood

Posted
Posted

00z Euro Op has a well-defined secondary low forming over the southern Appalachians on Friday, which is timed right to give southern VA and the Carolinas severe potential. The Euro Ensemble supports this to a degree (more so for timing, with support for the secondary low kind of there but gets washed out in the mean). The GFS maintains a more progressive system with little to no sign of a secondary low, which enhances the possibility for a line of storms along the cold front further north into DC/MD. However, the GFS Ensemble is bad on the timing, bringing the front through Thursday night instead of during the day Friday. Of note is the 06z GFS Op does develop the secondary low, but is still too fast to do much with it in our region.

In other words, typical April climo.

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