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Kmlwx

2020 Mid-Atlantic Severe Weather - General Thread

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Absolutely crushed in Arlington. Saw sign blow over and trees were bending with torrential rain falling sideways. Worst storm I've seen in years probably.

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1 hour ago, osfan24 said:

Radar and HRRR are both very meh the rest of the night.

F it! It’s over. Let’s aim for a drought. :lol:

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Just got power back.  It was a ridiculously weak storm to knock out power for over six hours but there it is.  Another 17 gallons of diesel.  Peak wind speed 42.9 mph.  Meh indeed!

This is probably a fire drill for what is to come tropical wise.

About six minutes before power went out...

 

ominous-sky.jpg

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Do these odd persistent thunderstorms tonight portend anything  for  Laura?  Could this line tonight  be a demarcation line of path tomorrow?

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Slight risk today.

From the Mount Holly AFD this morning-

With sufficient CAPE and fairly strong shear expected (30-40 kt 0-6 km bulk wind difference) along with alarmingly high values of storm- relative helicity (150+ J/kg), I am concerned storms will be capable of producing severe wind gusts and possibly a couple of tornadoes. As alluded to, the threat is conditional on the degree of instability that develops, but the tropical nature of the vertical profiles suggests to me that CAPE will need not be that large to promote an environment favorable for organized/rotating storms. SPC maintains a slight risk of severe storms today across the entire region, and this seems reasonable to me.

 

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6 hours ago, yoda said:

MRGL risk tomorrow for wind... SLGT risk for Thursday

     FWIW, the NAM nest soundings look way better for Wednesday, both in terms of shear and instability, and the simulated radar isn't bad.    HRRR looks pretty good too, and all of the CAMs suggest storms scattered through the area late Wednesday.     If I wanted to go into weenie mode, I'd note some low-level curvature in the hodographs.....

     Thursday has a better shortwave.     For now, the Thursday soundings in the NAM nest lack instability, but deep-layer shear is there, and the event certainly has potential too.    But I'm intrigued by what I'm seeing for the first event and would suggest that we could get a day 2 SLGT for Wednesday in the early afternoon SPC update.

 

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3 minutes ago, high risk said:

To expand on my interest in tomorrow, this is a pretty good look (minus the warm temps around 750 mb and weak winds in the layer just above):

1395806389_ScreenShot2020-09-01at11_11_30AM.thumb.png.245c04b748026ac99b0d91f5abc55ac6.png

That does look like a pretty good sounding for an isolated brief tornado or two 

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8 minutes ago, high risk said:

To expand on my interest in tomorrow, this is a pretty good look (minus the warm temps around 750 mb and weak winds in the layer just above):

1395806389_ScreenShot2020-09-01at11_11_30AM.thumb.png.245c04b748026ac99b0d91f5abc55ac6.png

i like what i see on the itty bitty radar sim for my back yard

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44 minutes ago, high risk said:

     FWIW, the NAM nest soundings look way better for Wednesday, both in terms of shear and instability, and the simulated radar isn't bad.    HRRR looks pretty good too, and all of the CAMs suggest storms scattered through the area late Wednesday.     If I wanted to go into weenie mode, I'd note some low-level curvature in the hodographs.....

     Thursday has a better shortwave.     For now, the Thursday soundings in the NAM nest lack instability, but deep-layer shear is there, and the event certainly has potential too.    But I'm intrigued by what I'm seeing for the first event and would suggest that we could get a day 2 SLGT for Wednesday in the early afternoon SPC update.

 

:lol: I just got back from looking at some of the mesoscale guidance for tomorrow and thought: "Hmm... I bet @high risk made an appearance in the severe thread this morning."

Now we patiently await the day that we are actually put under your namesake AND it verifies. 

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5 minutes ago, George BM said:

:lol: I just got back from looking at some of the mesoscale guidance for tomorrow and thought: "Hmm... I bet @high risk made an appearance in the severe thread this morning."

Now we patiently await the day that we are actually put under your namesake AND it verifies. 

      Am I THAT predictable?    B)     

      I can't even imagine what a synoptic setup would look like for an actual high risk here.     If it were to happen, my guess it would be for wind in a derecho event that has incredible predictability.       Derechos here haven't been particularly predictable in the past, but advances in NWP will eventually change that.

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2 minutes ago, high risk said:

      Am I THAT predictable?    B)     

      I can't even imagine what a synoptic setup would look like for an actual high risk here.     If it were to happen, my guess it would be for wind in a derecho event that has incredible predictability.       Derechos here haven't been particularly predictable in the past, but advances in NWP will eventually change that.

I don't think we will ever see a high risk here -- even the derecho in late June that was rampaging through the Ohio Valley the night of the infamous 00z LWX sounding (102/70 I think it was with nearly 6000 SBCAPE) only garnered a moderate risk on the 2000 SPC OTLK and the 0100 OTLK

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10 minutes ago, yoda said:

I don't think we will ever see a high risk here -- even the derecho in late June that was rampaging through the Ohio Valley the night of the infamous 00z LWX sounding (102/70 I think it was with nearly 6000 SBCAPE) only garnered a moderate risk on the 2000 SPC OTLK and the 0100 OTLK

I think the Northeast as a whole has seen one total high risk in history. I think it would be more likely for us to see a PDS Severe Thunderstorm Watch than a high risk. But - @high risk has a point. A lot of the outlook is based on predictability. If we have a CLEAR and OBVIOUS case of a massive severe outbreak days out ahead and it holds as we close, there could be a high risk at some point. And who knows what the future of the local climate will hold...

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9 minutes ago, yoda said:

I don't think we will ever see a high risk here -- even the derecho in late June that was rampaging through the Ohio Valley the night of the infamous 00z LWX sounding (102/70 I think it was with nearly 6000 SBCAPE) only garnered a moderate risk on the 2000 SPC OTLK and the 0100 OTLK

        This would be an awesome discussion over a few beers at an AMS conference.     For the 2012 event, CAM guidance was really limited.    The NAM nest had little handle on this event, and the HRRR had some good runs but was still experimental.     There were real questions about whether the derecho would survive crossing the mountains, and even at 1z, SPC still wasn't totally sure how far east it would maintain strength.      I still envision getting to a point in such an event where there is agreement that an intense derecho will blast through the Ohio Valley and make it to the coast, and SPC will launch the HIGH.      It won't happen right away, but we'll get there.

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1 minute ago, high risk said:

        This would be an awesome discussion over a few beers at an AMS conference.     For the 2012 event, CAM guidance was really limited.    The NAM nest had little handle on this event, and the HRRR had some good runs but was still experimental.     There were real questions about whether the derecho would survive crossing the mountains, and even at 1z, SPC still wasn't totally sure how far east it would maintain strength.      I still envision getting to a point in such an event where there is agreement that an intense derecho will blast through the Ohio Valley and make it to the coast, and SPC will launch the HIGH.      It won't happen right away, but we'll get there.

It's truly hard to believe that 2012 was already almost a decade ago. 

I agree - I think that had we had a good handle that the complex would maintain intensity as it approached, we could have qualified for a high. The sheer number of reports backs that up. If there was the equivalent of "post season analysis" like they do for hurricanes, that could have been a high risk day IMO. 

I doubt we ever see a TOR based high risk in this area. Although...isn't it more about the number of reports than the intensity of individual events? Say we had a vigorous system (perhaps tropical in nature or hybrid) and it was clear that while there wouldn't be EF-5 stuff...we'd get a large amount of EF-0 to EF-2 and it was high confidence - would that be enough to trigger a high hypothetically? I doubt SPC would ever do that for a tropical system, though. 

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The other thing you have to remember - even with high confidence...the higher the outlook the higher the "egg on face" potential for SPC. There's already the old saying that meteorologists are always wrong...very few SPC forecasters would have the stomach to call a high risk for the nation's capital unless it was absolutely necessary. 

It's one thing to call a high where the local population understands what the risk categories mean and are familiar with severe weather. DC tends to have a "panic mode" inherently built into the population (just look at 495 with a half inch of snow). Can you imagine what a high risk would do to lay people around here? 

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Just now, Kmlwx said:

The other thing you have to remember - even with high confidence...the higher the outlook the higher the "egg on face" potential for SPC. There's already the old saying that meteorologists are always wrong...very few SPC forecasters would have the stomach to call a high risk for the nation's capital unless it was absolutely necessary. 

It's one thing to call a high where the local population understands what the risk categories mean and are familiar with severe weather. DC tends to have a "panic mode" inherently built into the population (just look at 495 with a half inch of snow). Can you imagine what a high risk would do to lay people around here? 

True.  You could only go high risk here if the event was unfolding with as you say numerous tornadoes (EF2 or something) or a derecho coming in from the west.

The derecho in 2012 however, caught the region, including local TV mets off-guard per the NWS report though.

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