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2017 Severe Thread


mappy

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20 hours ago, high risk said:

Looking at the evening guidance, the timing has definitely slowed down which makes this a more intriguing event for much of the area.   Both NAM and RAP/HRRR bring 1000+ sfc cape into our area by midday.   The shear gets weaker as we go into the afternoon due to the sfc winds veering, but there looks to be a window (perhaps between 11AM and 2PM) when instability and shear align.    The fail mechanism would be that both the NAM nest and HRRR show a lot of convection through the area during the early morning hours (2 rounds in some HRRR solutions), and while those solutions verbatim clear us out quickly behind that activity, we've all seen svr days here bust due to morning rain/convection reinforcing the wedge and preventing heating.      Thunder with widespread heavy rainfall seems like a fairly good probability during the early hours;  whether there is a SVR event behind that remains to be seen but is not a total longshot either.

     I wanted to bring attention to the post I wrote around midnight last night.    I'm showing it again not to toot my own horn, but to emphasize the point made in here earlier about the amazing progress that has been made in NWP.    In this post, all I did was rehash what the guidance was showing yesterday evening, and it painted a pretty damn good picture of how today would evolve.    The runs earlier this morning then showed the finer details of that line sweeping southwest to northeast across the area.     Not every forecast is that good, and some end up really poor, but it's amazing to see from where NWP has come and where it's going.    

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1 minute ago, high risk said:

     I wanted to bring attention to the post I wrote around midnight last night.    I'm showing it again not to toot my own horn, but to emphasize the point made in here earlier about the amazing progress that has been made in NWP.    In this post, all I did was rehash what the guidance was showing yesterday evening, and it painted a pretty damn good picture of how today would evolve.    The runs earlier this morning then showed the finer details of that line sweeping southwest to northeast across the area.     Not every forecast is that good, and some end up really poor, but it's amazing to see from where NWP has come and where it's going.    

 Definitely. The radar this afternoon and some of last night's high-res model simulations for this afternoon looked nearly identical.

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Creeks and streams running real high up here. 



I saw the Gunpowder River earlier and it was running real fast, quite turbulent and much higher then I've seen it. Given the flood watch, I can only imagine what it's like further south
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8 hours ago, WxWatcher007 said:

Scratch. Excellent storm day. One confirmed TOR in DC and probably another one here at the basin. Trifecta possible with the area around Union Station? I heard this might be the first April tornado for DC proper since 1950?

 

Ha, no not that far back. Last time a tornado went into DC proper was the outbreak of 9/24/01. 

An EF1 that started in VA, and ended in Central DC

An EF3 that started in N DC and ended in MD (this is the same tornado that killed 2 in College Park)

Prior to that an EF0 touched down briefly in May of 1995

ETA: ah ****, you said in April. Then yes, first April tornado since 1950. My bad. 

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2 hours ago, AmericanWxFreak said:

 

SPC too kinda 

Ian has a nice .gif of this.  Denser population DC-PHL means higher bust potential.  Outside of us wx nerds, there's no problem with throwing a D1 slight risk out, IMO, especially with the dynamics of the setup.

 

 

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11 minutes ago, MN Transplant said:

Went right over my wife's office in Pentagon City.  I gave her crap for saying there were "little tornadoes" around.  Oops.

 

So, I guess I saw my first tornado yesterday.  From my point of view, the rotation wasn't evident enough for me to be confident, but the cloud motion was unlike anything I've ever seen.

Given the number of tornado warnings that don't verify around here, it is supremely ironic that none of the tornadoes in DC yesterday occurred under a tornado warning.  It just goes to show how tough a job the NWS folks have, especially with these QLCS spin-ups.  By the time they show up on radar, they're gone.  Nonetheless, given how weak these were, I'm not sure a tornado warning was really necessary.  The winds associated with these EF0s are not much different than the wind speeds advertised in those warnings.

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  • 3 weeks later...
1 hour ago, high risk said:

Since we track winter events at day 7, why not do the same for svr threats?   Thinking that next Monday has good potential here.   Strong trough is likely to approach with strong low level and upper jets, good moisture in place, and a well-timed cold front.

True... LWX has mentioned that day in its LR disco

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2 hours ago, high risk said:

Since we track winter events at day 7, why not do the same for svr threats?   Thinking that next Monday has good potential here.   Strong trough is likely to approach with strong low level and upper jets, good moisture in place, and a well-timed cold front.

If the radar doesn't look like this, it's a bust. B)

 

August 26, 2016.png

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In all seriousness though, don't completely sleep on Saturday though. While it's certainly a bit of a stretch right now, if storms early Saturday in the Midwest can remain organized through the day they may meet fairly decent CAPE w/ fairly decent effective shear in the area later in the day. But this is a little more than speculation at this point.

I will low-key watch it for now.  

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1 hour ago, yoda said:

I like the soundings from the 12z NAM for Saturday afternoon and evening :lol:

4000 SBCAPE at KIAD 00z SUN with LI's at -7 and 0-6km shear 35-40 kts and MLCAPE around 3500

 

   agree fully that the environment for Saturday is pretty volatile - just not sure if we can get storms to initiate.    But there is a hint of initiation in the 12z NAM, so it bears watching.

   the better forcing, along with impressive wind fields through the column, is still on track for Monday.    Still some question about how much instability will be available, but I'm still on board.

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12 minutes ago, high risk said:

 

   agree fully that the environment for Saturday is pretty volatile - just not sure if we can get storms to initiate.    But there is a hint of initiation in the 12z NAM, so it bears watching.

   the better forcing, along with impressive wind fields through the column, is still on track for Monday.    Still some question about how much instability will be available, but I'm still on board.

Saturday looks better the further north you are ATM. I'm watching what any potential MCS/remnant MCS does in the Midwest/Ohio Valley early in the day. Northern areas look to have the greatest threat..........should anything like this materialize. 

Still very uncertain.

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