3/16/26 Severe Weather Event Thread (Moderate Risk) | Latest: 15% TOR, 60% WIND, 5% HAIL

[Kmlwx]

Continuing discussion and eventually observations/nowcast posts for the Monday severe weather event potential can go here. @WxUSAF or other mods please pin this thread if you get the chance. 

15% TOR and 60% WIND are extremely rare in these parts. While I am not downplaying anything - I do think the appearance of 60% wind has a lot to do with the new SPC outlook methodology. Nonetheless, an active weather day tomorrow seems on tap. 

Usual failure modes still exist (stabilizing cloud cover or early day showers)

The shear environment is pretty insane. 

[snowfan]

[SomeguyfromTakomaPark]

Wow, haven’t seen this in a while.  Maybe August 2023 was the last moderate risk day here?  At least the QLCS holds off until after school dismissal and kids have a chance to get home. 

[dailylurker]

19 minutes ago, SomeguyfromTakomaPark said:

Wow, haven’t seen this in a while.  Maybe August 2023 was the last moderate risk day here?  At least the QLCS holds off until after school dismissal and kids have a chance to get home. 

Very impressive setup. Especially for March. Looks like a pretty exciting event. I still wish I was up in the UP for the blizzard. If I wasn't back to my busy season I would be up in Marquette right now. 

[George BM]

Well hello there pinned severe thread. 

First time we've done one since February 25, 2017 IIRC when Ian made one for that event (That event produced an EF-1 in La Plata IIRC).

[Imgoinhungry]

Looks like a bit of a later start per nam and hrrr recent runs? Hopefully no impact to school dismissal.


.

[CAPE]

SPC

...Carolinas into MD/PA and vicinity...
   Areas of showers may occur early in the day especially but should
   rapidly lift north, allowing areas of heating and gradual
   destabilization over the entire area. As the surface trough deepens,
   low-level wind will back and strengthen throughout the day.
   Supercells producing tornadoes appear most likely ahead of the cold
   front from SC into NC and southern VA. Models vary with degree of
   instability, but strong tornadoes do appear possible with effective
   SRH of at least 300-400 m2/s2. Fast storm motions over 50 kt suggest
   a long tracked tornado will be possible.

   Meanwhile, a robust line of storms will develop as the cold front
   pushes east, stretching from the Carolinas to southern NY. With a
   moist air mass and large-scale support, this line is expected to
   produce particularly damaging winds, along with QLCS tornadoes
   across the remainder of SC/NC, VA, MD, and much of southern PA. This
   will likely peak during the late afternoon hours. The activity may
   eventually interact with cool trajectories off the Atlantic during
   the evening.

[Weather Will]

WB 6Z 3K NAM for Monday evening starting at 5 pm

[Eskimo Joe]

06z HRRR had a UHI track from Dulles right to York, PA, another right over DC< and two more through Stafford and La Plata. Wow.

[yoda]

Cross posting in here

23 minutes ago, Eskimo Joe said:

 

 

[TSSN+]

19 minutes ago, Eskimo Joe said:

06z HRRR had a UHI track from Dulles right to York, PA, another right over DC< and two more through Stafford and La Plata. Wow.

Urban heat island? lol 

[yoda]

3 minutes ago, TSSN+ said:

Urban heat island? lol 

Updraft Helicity Index

[SnowenOutThere]

Thinking I might chase tomorrow. Any met want to tell me a good grounding location? I was thinking orange VA

[Kmlwx]

Just now, SnowenOutThere said:

Thinking I might chase tomorrow. Any met want to tell me a good grounding location? I was thinking orange VA

If you do, please be careful. Fast storm motions will make this potentially chaotic. 

[Kmlwx]

57 minutes ago, Imgoinhungry said:

Looks like a bit of a later start per nam and hrrr recent runs? Hopefully no impact to school dismissal.


.

I do think linear convective systems in our region tend to roll through a bit earlier than even short range models predict. There are exceptions, of course - but with a solid line - it wouldn't shock me to see it bump 1-3 hours earlier as we close. 

[SnowenOutThere]

3 minutes ago, Kmlwx said:

If you do, please be careful. Fast storm motions will make this potentially chaotic. 

I have no interest in 0 metering. More a storm structure guy. 

[dailylurker]

3 minutes ago, SnowenOutThere said:

Thinking I might chase tomorrow. Any met want to tell me a good grounding location? I was thinking orange VA

Urban chasing is tricky. I try to target areas where there's a less traffic but a good road system. Let use north Maryland for example. 70 is good for getting in but not for chasing an actual tornado. I chased out by Thurmont in Carroll County. Good roads, good views, and no traffic mayhem. You don't want to be stuck in traffic with an ef 3 tossing cars and coming at you. Watch for trees. I take my chainsaw just in case I need to cut my way out. Be careful and good luck. Btw. I'm not a met. I'm just nuts about weather lol. I'd join you if I wasn't working. 

[Kmlwx]

Going to wait until 12z models before I do my little write-up for my office. While a ton of people at work (including in management) read my emails - they seldom apply my messaging to their actual decision making  - which I don't blame them since I'm a weather weenie. But so far it has burned them a few times (during snow events) when they've closed too late (once people were already at the office) or haven't closed early enough in the afternoon leading to people having 3-5 hour commutes. 

I've *never* seen them release early for something other than snow...And I'm physically onsite tomorrow until 5:30pm. Great....with no windows too! 

[Kmlwx]

CSU MLP mostly held steady with wind but maybe tailored back the TOR risk just a touch. I'm not entirely shocked - and I've been thinking even with some models showing pre-line cells, that this would be a wind dominated event with some brief QLCS spinnys. Nonetheless - I think SPC is hitting the threat level very well! 

[TSSN+]

39 minutes ago, yoda said:

Updraft Helicity Index

Ya I was kidding haha. 

[TSSN+]

10 minutes ago, Kmlwx said:

CSU MLP mostly held steady with wind but maybe tailored back the TOR risk just a touch. I'm not entirely shocked - and I've been thinking even with some models showing pre-line cells, that this would be a wind dominated event with some brief QLCS spinnys. Nonetheless - I think SPC is hitting the threat level very well! 

I’m interested to see how this plays out. I think this looks more realistic than the 60% wind. At least into Maryland maybe more impressive over central/eastern VA and NC. To me it doesn’t look all that impressive on models. I hope I’m right and we don’t get widespread wind damage. I don’t want to be without power for an unknown amount of time. 

[Kmlwx]

11 minutes ago, TSSN+ said:

I’m interested to see how this plays out. I think this looks more realistic than the 60% wind. At least into Maryland maybe more impressive over central/eastern VA and NC. To me it doesn’t look all that impressive on models. I hope I’m right and we don’t get widespread wind damage. I don’t want to be without power for an unknown amount of time. 

Well one thing is - I wonder if those CSU-MLP maps have to be adjusted to account for the new SPC methodology. 

[Lucy Pull]

3 minutes ago, Kmlwx said:

Well one thing is - I wonder if those CSU-MLP maps have to be adjusted to account for the new SPC methodology. 

Agree with this premise. 
 

Do not think we would be seeing 60% wind probabilities with the old methodology.

 

[Kmlwx]

For those of you who haven't done any deep diving into the SPC videos for the new outlook styles - you could theoretically get an absurdly high PERCENTAGE now but with little or no CIG. That would be applied to times when 58-65mph winds for example might be a near lock and widespread - but the magnitude might not hit the 70-80mph+ range. 

The CIG categories are probably going to be the more important things to watch with this new era. 

[TSSN+]

2 minutes ago, Kmlwx said:

For those of you who haven't done any deep diving into the SPC videos for the new outlook styles - you could theoretically get an absurdly high PERCENTAGE now but with little or no CIG. That would be applied to times when 58-65mph winds for example might be a near lock and widespread - but the magnitude might not hit the 70-80mph+ range. 

The CIG categories are probably going to be the more important things to watch with this new era. 

Too confusing to me and I’m sure even more to general public. 

[yoda]

Cross posting in here for @Mrs.J

6 minutes ago, Mrs.J said:

*URGENT*

So I need some help. 

The older Ms. J is currently on a film project for her senior capstone aka student run project. She is a AD, assistant Director, on the current project. Anyways part of the AD’s job is safety. They are shooting in studio on AU’s campus Media Production Center. It is in the basement of the building so thinking that is the shelter for the building anyways. She has asked me to let her know the threat level. She texted me this morning. 

“if it is seeming enough that we either may lose power or have to shelter in place worse case scenario I have to hold a safety meeting tonight to tell everyone to get here safely tomorrow and another one tomorrow with protocols."

If anyone can advise me. I have been following along with the two threads here on this set up but I am far from an expert on this. She is really big on doing her job correctly and wants to keep everyone safe so I told her I would help her with this as much as I can. Because her and I are huge weather buffs I am happy that she is on top of this as it may be something that is overlooked by others. I thank anyone in advance if I can give her a clearer understanding for her area of NW DC. 

 

[Lucy Pull]

13 minutes ago, TSSN+ said:

Too confusing to me and I’m sure even more to general public. 

I feel that the CIG categories could be confusing to the general public but I also feel the old lower probabilities weren’t too helpful to the general public either. Especially before enhanced/marginal were introduced. 

I do think the higher probabilities gets the word out better for borderline severe/sub severe squall lines and line segments that produce widespread winds. 

[Kmlwx]

I think SPC in general (probably more a discussion for the general severe thread) is not geared well towards public consumption. A person sees "slight risk" and doesn't take the threat seriously.

Or they see "10% tornado" and are like big deal. We as weather weenies know how to evaluate this - but average Joe is not now, or in the past going to fundamentally understand SPC outlook categories or percentages. Some of the switch to "level X out of X" has helped - but hasn't eliminated the issue.

[Lucy Pull]

CIG categories will also be helpful in differentiating QLCS spinups from tornado producing supercell threats.
 

I believe this will also be helpful for tornado threats associated with tropical systems.

[TSSN+]

12z hrrr has a few cells west of dc that push ne into Maryland then kinda merge with the line.