2024 Severe Weather General Discussion

[Kmlwx]

10 minutes ago, Eskimo Joe said:

The orientation and proximity of the warm front on Monday would have me lean towards the NAM family. Definitely a decent set up for tornadoes.

 

[Kmlwx]

Radar looks good for today!

[yoda]

On 2/20/2024 at 9:15 AM, WxWatcher007 said:

@Kmlwx

The timeless scale. Each person has to be on board for the step to be activated. 
 

 

28 minutes ago, Eskimo Joe said:

The orientation and proximity of the warm front on Monday would have me lean towards the NAM family. Definitely a decent set up for tornadoes.

Uh oh

[Eskimo Joe]

 

29 minutes ago, Kmlwx said:

 

 

11 minutes ago, yoda said:

Uh oh

Chill out. 

[dailylurker]

I hope to see some flashing in the sky once it's dark from those storms in Northern MD. I just sprayed my garden. I hope the rain stays away for tonight. 

[yoda]

I'm going to go with 5/15/15 on the Day 2 morning update.  

[southmdwatcher]

Well lets end up with 10 percent hatched, 30 and 30

[WxWatcher007]

How often does a D3 slight happen?

[Kmlwx]

5 minutes ago, WxWatcher007 said:

How often does a D3 slight happen?

Totally going off of my awful memory - but I think we do get them a good bit. Particularly the fairly generalized 15% ones. I feel like there was one time I can remember in semi-recent memory that there was a 30% day 3 maybe...I might be wrong. 

If you're asking @Eskimo Joe - having SPC go big on day 2 or beyond...is a jinx. 

[Kmlwx]

23 minutes ago, southmdwatcher said:

Well lets end up with 10 percent hatched, 30 and 30

30% for hail is pretty unusual around here. It might even be more uncommon than 45% wind. And of course we all know 10% hatched TOR is nearly unheard of except in our juiciest events. We definitely won't see anything like that in the day 2 tomorrow. I'm inclined to hedge lower for now even for the first day 1 outlook on Monday. 

[high risk]

Put me down for 5/15/15.     If we went entirely off of the NAM Nest, it would be an ENH for sure, but several CAMs have some morning or midday convection that ruin the lapse rates.

[WEATHER53]

Petered out in Kemp Mill but Zoo getting hit hard 

[Kmlwx]

A quick/undetailed look at the guidance is a little less impressive this morning. Interestingly...some models like the experimental RRFS A and MPAS ones show almost nothing for many of us Mon afternoon. NAM and NAM nest soundings still look solid - but they have backed off on some of the parameters. 

SPC day 2 outlook indicates the system has trended weaker and they went with 2/15/15

We'll see how things trend on today's guidance. If it bleeds any further it will just be a garden variety isolated severe day by the time we get to tomorrow afternoon. 

[Kmlwx]

Few comments about the 12z 12km NAM so far - it seems to have lots of clouds NW of I-95...subsequently the really high CAPE is SE of the corridor. It also pushes the line through earlier than prior runs. 

[Kmlwx]

The 3km NAM looks better in regards to MLCAPE - seemingly focuses a corridor running NW to SE roughly along the Potomac (maybe the front @Eskimo Joe was talking about). Problem that I have is that we've seen the NAM nest have dews too high at this lead time before - and that could be inflating the instability parameters. I could make the argument for an absolute bust or a higher end day at this point...sounds typical of our area and severe  

A good example of the dewpoint argument is the long range 12z HRRR (screenshot below). You can see that the best 70+ dewpoints get limited to SE of the DC to Baltimore corridor. Believe @high risk has said the HRRR sometimes mixes out the dews too much - so that could be a reason to give this solution less attention. 

One thing that has my interest is the fact that early day activity, while it could dampen severe chances, it could moisten things up to keep dewpoints a bit elevated (like the NAM and NAM nest). Early day activity can also leave behind boundaries (as we've seen before). The issue is that it can also stabilize us too much. It's such a crap chute and gamble for severe around here. Push/pull situation. 

My gut feeling is that we all (or most of us) hear thunder tomorrow...but that the "focused" severe threat might reside south of a line MD32 and perhaps east of an imaginary line running maybe Rockville down to EZF. That might be a little pessimistic...but I'd rather be cautious at this point. There's enough guidance that really skunks us to give me pause. 

 

[high risk]

23 minutes ago, Kmlwx said:

The 3km NAM looks better in regards to MLCAPE - seemingly focuses a corridor running NW to SE roughly along the Potomac (maybe the front @Eskimo Joe was talking about). Problem that I have is that we've seen the NAM nest have dews too high at this lead time before - and that could be inflating the instability parameters. I could make the argument for an absolute bust or a higher end day at this point...sounds typical of our area and severe  

A good example of the dewpoint argument is the long range 12z HRRR (screenshot below). You can see that the best 70+ dewpoints get limited to SE of the DC to Baltimore corridor. Believe @high risk has said the HRRR sometimes mixes out the dews too much - so that could be a reason to give this solution less attention. 

 

 

       Everything you wrote about the HRRR and NAM Nest is correct, but I don't think that tomorrow is about mixing.   It's about clouds and convection from lead shortwaves.   The NAM Nest is a round of storms late tonight and a second round in the very early afternoon, but the second round is mostly south and southeast.   The northern areas therefore recover enough during the day for a good round of storms at the end of the day.   The HRRR has the early morning stuff, and then round 2 around midday is more expansive.    It still warms up behind it, but the surface winds veer, and there is little convergence along the front except in far northern MD, where the HRRR does have a round 3 at the end of the day.   I won't go through every CAM, but the keys are heating and wind direction by mid afternoon.    If we are heating and the winds are southwesterly, a big late day show is unlikely.   If we are heating and the winds are more southerly, I think we'll have at least some coverage of SVR.

[Kmlwx]

GFS drops dewpoints into the low to mid 60s in a little pocket over the metro area  

[Eskimo Joe]

2 hours ago, high risk said:

       Everything you wrote about the HRRR and NAM Nest is correct, but I don't think that tomorrow is about mixing.   It's about clouds and convection from lead shortwaves.   The NAM Nest is a round of storms late tonight and a second round in the very early afternoon, but the second round is mostly south and southeast.   The northern areas therefore recover enough during the day for a good round of storms at the end of the day.   The HRRR has the early morning stuff, and then round 2 around midday is more expansive.    It still warms up behind it, but the surface winds veer, and there is little convergence along the front except in far northern MD, where the HRRR does have a round 3 at the end of the day.   I won't go through every CAM, but the keys are heating and wind direction by mid afternoon.    If we are heating and the winds are southwesterly, a big late day show is unlikely.   If we are heating and the winds are more southerly, I think we'll have at least some coverage of SVR.

Bingo. Probably a decent slight or enh risk tomorrow.

[batmanbrad]

looks like a 5% TOR probability was added in the latest day 2 outlook from SPC for much of our area.  Still SLIGHT risk though...

[Eskimo Joe]

22 minutes ago, batmanbrad said:

looks like a 5% TOR probability was added in the latest day 2 outlook from SPC for much of our area.  Still SLIGHT risk though...

Makes sense. Don't think a 10% is needed, but we could definitely get a 30% wind tomorrow. 

[Eskimo Joe]

Flying from Midway to BWI this afternoon through this mess should be fun.

[MN Transplant]

NCAR is running FV3 and MPAS-based ensembles for NOAA/NSSL's Spring Hazardous Weather Testbed  https://ensemble.ucar.edu/

 

Neither are overly excited about Monday.

[NorthArlington101]

NCAR is running FV3 and MPAS-based ensembles for NOAA/NSSL's Spring Hazardous Weather Testbed  https://ensemble.ucar.edu/
 
Neither are overly excited about Monday.

Lame.

Was considering “storm chasing” tomorrow in EMD since I have no exciting Memorial Day plans. Let something spin up as it goes over the Bay and go from there. Guess I’ll see what happens tomorrow.

[southmdwatcher]

Don't know at all if this will impact our chances tomorrow, but SPC just upgraded western KY/TN into Missouri and Arkansas to Moderate for tornadoes, and the enhanced(10 percent hatched area) VERY significantly increased in areal coverage into northern AL/MS and all of KY/TN into far southwest VA.

[southmdwatcher]

Storm Prediction Center May 26, 2024 2000 UTC Day 1 Convective Outlook (noaa.gov)

 

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0320 PM CDT Sun May 26 2024

Valid 262000Z - 271200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS
SOUTH-CENTRAL AND SOUTHEAST MISSOURI...FAR NORTHEAST
ARKANSAS...SOUTHERN ILLINOIS...FAR SOUTHWEST INDIANA...WESTERN
KENTUCKY...AND NORTHWEST TENNESSEE....

...SUMMARY...
Severe storms are expected from the Ozarks this afternoon and
evening to the Ohio and Tennessee Valley tonight. Tornadoes, some
strong to intense, and large to very large hail are the primary
threats this afternoon and evening with an evolving overnight severe
wind/embedded tornado threat tonight.

Primary focus of this outlook update was a moderate risk upgrade
from south-central Missouri into western Kentucky and northwest
Tennessee. An EML has advected across this region in the wake of
morning convection which has permitted strong heating and
destabilization. The outflow boundary and the destabilized region
north of this boundary provide a vorticity rich low-level airmass
favorable for tornadoes. Supercells are already starting to develop
in the hot and unstable airmass across southwest Missouri and will
move toward this vorticity rich airmass this evening. Additionally,
a strengthening low-level jet is expected across this area tonight
which will elongate low-level hodographs. Most members of the 18Z
and 19Z WoFS show several intense, long track supercells through
this region later this evening with increased 0-2km UH
probabilities, giving more supporting evidence for the rapidly
evolving tornado threat. Given the aforementioned factors, several
strong to intense tornadoes are possible this evening. See MCD #980
for additional information about the evolving threat in this region.

Eventually, these supercells will likely congeal into an MCS which
amid extreme instability, strong shear, and steep lapse rates, will
likely have a significant wind threat into the late evening and
early overnight hours. 

In addition, added a small marginal risk across southwest South
Dakota and northern North Dakota where a few stronger storms have
developed amid weak instability and moderate shear. See MCD 982 for
additional information about this threat.

..Bentley.. 05/26/2024

.PREV DISCUSSION... /ISSUED 1140 AM CDT Sun May 26 2024/

...Ozarks/Arklatex to Ohio/Tennessee Valleys and south-central
Appalachians...
Ongoing/long-lived bowing complex, with a history of measured severe
gusts and wind damage, continues to move east across central
KY/northern TN at 16z.  The downstream environment continues to
destabilize as diurnal heating of upper 60s/near 70 def F dewpoints
continues, and this complex is expected to continue moving east
through this afternoon while maintaining a risk for damaging gusts
and embedded QLCS circulations.

In the wake of this convective system, a pronounced theta-e gradient
has become established from northern TN westward, becoming more
diffuse over southern MO, where strong heating is occurring.  Severe
thunderstorms are forecast to redevelop this afternoon across
southern MO within a strongly sheared environment characterized by
50 kts of westerly shear, and strong MLCAPE. Supercell structures
should be the dominant convective mode for several hours, with a
risk for all severe hazards including very large hail and strong
tornadoes. 

The convective system may congeal with time into more of a linear
structure, with a risk for all hazards continuing into the overnight
hours within an amply-sheared and moderately unstable environment.
The Enhanced Risk has been expanded farther south over portions of
northern MS/AL/far northwest GA based on 12z HREF calibrated
guidance.

[Eskimo Joe]

18z HRRR seems to be pooling some low level moisture better east of I-81. Good to see.

[southmdwatcher]

That line of strong to severe storms crossing the crest of the Appalachians, in West Virginia is not immediately followed up by any storms as of this moment. Tomorrow could be quite interesting in this region.

[nj2va]

STW posted for the far western counties until 11p. Hoping that line produces here at Deep Creek!

[high risk]

1 minute ago, nj2va said:

STW posted for the far western counties until 11p. Hoping that line produces here at Deep Creek!

    Yeah, that line will still pack a punch for at least several more hours as it moves east across northern VA and western MD.    The question is how far east it can advance as it encounters decreasing instability.   Different HRRR cycles have shown it dramatically weakening  in the western suburbs, as it crosses the Potomac, or over central MD.       Some severe wind into at least part of the immediate DC area is certainly on the table.

[Kmlwx]

Completely unscientific reasoning - but if that line can deliver some good storms/gusts (even if sub-severe) to the area...this has the feeling of a mini-heater combining today and tomorrow. We are due...that's my only reasoning really.