Severe storms 2015 general chatter

[Ian]

Yeah the timing is something. I can really only think of maybe 3 to 5 other late night storms since I've lived here. Not sure any were severe. Derecho was close to late night but was rolling in before people went to bed etc. Did browse mesoanalysis, env was decent but not spectacular though again we are talking 1a. The cell merger stuff may have had some impact for sure too. Almost looked like a long tracked microburst. Wasn't crazy impressive on radar which does make you wonder about the soil. Saw more uprooted than snapped stuff.

[ravensrule]

Yeah the timing is something. I can really only think of maybe 3 to 5 other late night storms since I've lived here. Not sure any were severe. Derecho was close to late night but was rolling in before people went to bed etc. Did browse mesoanalysis, env was decent but not spectacular though again we are talking 1a. The cell merger stuff may have had some impact for sure too. Almost looked like a long tracked microburst. Wasn't crazy impressive on radar which does make you wonder about the soil. Saw more uprooted than snapped stuff.

It was Friday night around 11p.m.. Not all of us are party animals like yourself   . I was actually sleeping and it woke me up and scared the crap out of me. Thank G-D for generators. My neighbors were without power for a week.

[WxUSAF]

Yeah the timing is something. I can really only think of maybe 3 to 5 other late night storms since I've lived here. Not sure any were severe. Derecho was close to late night but was rolling in before people went to bed etc. Did browse mesoanalysis, env was decent but not spectacular though again we are talking 1a. The cell merger stuff may have had some impact for sure too. Almost looked like a long tracked microburst. Wasn't crazy impressive on radar which does make you wonder about the soil. Saw more uprooted than snapped stuff.

Good point about the wet soil.  

 

I had about 0.3" from last night.  Happened to wake up while it was raining, but wasn't the rain that woke me up.  Didn't sound particularly heavy.  

[mattie g]

Good point about the wet soil.

I had about 0.3" from last night. Happened to wake up while it was raining, but wasn't the rain that woke me up. Didn't sound particularly heavy.

The dog woke us up, but the thunder probably would have gotten me if it weren't for our pup getting the beat on it.

We had about .4" or overnight, and it's raining harder now than at any point last night...at least here.

[Sparky]

It's a neat event, because the environment in place was probably pretty good, but 1AM severe storms are so strongly against climatology here that there really wasn't much thought about a threat.   Based on RAP/NAM analysis forecasts, we probably had 1500-2000 sfc-based cape and 45 kt or so of 0-6 km shear, along with fairly strong forcing - certainly enough to justify an isolated severe threat.    If this had been during the late afternoon, we probably would have been boxed, but again, no one was really thinking severe at 1AM.     Heck, SPC which issued  500 watch boxes earlier Tuesday afternoon didn't even deem this overnight event worthy of a mesoscale discussion.

The summer equivalent of 1/25/00.

[yoda]

Sneaky isolated severe threat this evening? 5% wind and 2% tor on 1300 SPC OTLK

[mitchnick]

Sneaky isolated severe threat this evening? 5% wind and 2% tor on 1300 SPC OTLK

I would think that something would come out of a spin like that over WV this time of year.

[weatherCCB]

Sun peaking thru here.

D.P. 72

If we can get some clearing, maybe a chance.

Otherwise looks like heavy rain.

[Eskimo Joe]

Cells along I-70 look they want to meh.  Some good downpours at the very least.  

[Eskimo Joe]

Pity Meso (20%)  LINK

[yoda]

Yeah... about those 00z NAM soundings for Thursday evening...  i would guess MCS remnants?

[yoda]

Meh

 

[yoda]

 

[yoda]

06z soundings even more ridiculous from the NAM

 

And yes, I know its the NAM... but its the only thing interesting right now on the horizon

[yoda]

12z NAM and 4km NAM have some decent parameters in the area around 21z-00z Thursday... GFS not impressed

[yoda]

06z NAM sup parameter at 21z THUR

 

 

 

[high risk]

Thursday evening definitely catches my eye, as there appears to be a window for severe storms and possibly supercells in the DC area as a weak sfc low and associated frontal boundary move through the area.    The NAM is obviously much more bullish than the GFS with instability, but I think it may be reasonable to expect moisture to pool near the sfc low and allow for higher cape.   The latest SREF mean has around 2000 cape here tomorrow evening.    It's weird to be looking at svr set up with only 30 kt or so at upper levels, but low-level shear is decent.    There are also possible right rear quad effects of the upper jet to assist with lift.

[yoda]

Thursday evening definitely catches my eye, as there appears to be a window for severe storms and possibly supercells in the DC area as a weak sfc low and associated frontal boundary move through the area.    The NAM is obviously much more bullish than the GFS with instability, but I think it may be reasonable to expect moisture to pool near the sfc low and allow for higher cape.   The latest SREF mean has around 2000 cape here tomorrow evening.    It's weird to be looking at svr set up with only 30 kt or so at upper levels, but low-level shear is decent.    There are also possible right rear quad effects of the upper jet to assist with lift.

 

Some of the soundings are printing out 3000-4000+ SBCAPE

[Kmlwx]

Some of the soundings are printing out 3000-4000+ SBCAPE

You and I both know those are too high

[yoda]

You and I both know those are too high

 

Yes

 

09z SREFs at 21z have DC near the mean 2000 MLCAPE marker

[Eskimo Joe]

Looks like a Thurmont Special which a is great because we're taking a crew to fill in the their fire department tomorrow afternoon and evening.

[yoda]

Once again, 12z NAM soundings back to their silliness across the area

[yoda]

12z NAM and HIRES-NAM sup composites for 21z THUR

 

 

 

[Kmlwx]

Meh

[high risk]

   what do you see as "silly"?    I'm looking at the structure progged for 21z tomorrow, and it looks reasonable.   Or do you mean that it's silly how good it looks for severe weather?

 

    to me, the GFS sounding is "silly", as it mixes out big-time and generates a very deep and fairly dry PBL.   That doesn't look too reasonable to me.

 

    The NAM is really interesting, because the progged shear at 18z is terrible, but it quickly gets it act together just before 21z as the trough approaches.   Even the GFS shear isn't terrible, although it lacks the impressive low-level directional turning that the NAM has.

 

 

Once again, 12z NAM soundings back to their silliness across the area

[Eskimo Joe]

Meh

 

We've seen time and time again the NAM go out on its own an generate unrealistic parameters this probably is no difference.  I hope I'm wrong and we all get blasted.

[yoda]

   what do you see as "silly"?    I'm looking at the structure progged for 21z tomorrow, and it looks reasonable.   Or do you mean that it's silly how good it looks for severe weather?

 

    to me, the GFS sounding is "silly", as it mixes out big-time and generates a very deep and fairly dry PBL.   That doesn't look too reasonable to me.

 

    The NAM is really interesting, because the progged shear at 18z is terrible, but it quickly gets it act together just before 21z as the trough approaches.   Even the GFS shear isn't terrible, although it lacks the impressive low-level directional turning that the NAM has.

 

Sorry, should have specified better... the parameters the 12z NAM were showing were "silly" because we don't see those types of values over here in the LWX CWA

[Kmlwx]

   what do you see as "silly"?    I'm looking at the structure progged for 21z tomorrow, and it looks reasonable.   Or do you mean that it's silly how good it looks for severe weather?

 

    to me, the GFS sounding is "silly", as it mixes out big-time and generates a very deep and fairly dry PBL.   That doesn't look too reasonable to me.

 

    The NAM is really interesting, because the progged shear at 18z is terrible, but it quickly gets it act together just before 21z as the trough approaches.   Even the GFS shear isn't terrible, although it lacks the impressive low-level directional turning that the NAM has.

 

21z is pretty ideal timing for severe in our area too. If we can hold that and keep it from slipping too early or too late I'll feel good. Timing is our issue like 80 percent of the time with the other 20 percent going to shear or lapse rates lol. 

[high risk]

  here are the NAM and GFS soundings valid at 21z tomorrow.   You can see why the supercell index values are so high - that is excellent low-level shear in the NAM.    The GFS has veered low-level flow, so the profile ends up more unidirectional with some modest speed shear.   The more westerly low-level flow may explain why the model mixes out the boundary layer so much.

[Ian]

I used my secret powers http://www.americanwx.com/bb/index.php/topic/46604-july-9-tornado-watch-and-slightenh-risk/