2021 Mid-Atlantic Severe Weather - General Discussion

[nj2va]

48 minutes ago, yoda said:

We might get our first rumbles of thunder and lightning tomorrow evening

Let’s get thunderstorm season going.

[George BM]

45% TOR area added now.

 

[yoda]

Well hmmm -- from this afternoon's LWX AFD re the chance of some storms

@high risk @Kmlwx

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Low pressure looks poised to track near or just south of the
southern boundary of our CWA (across central VA to near southern
MD). This puts most of the region in the cool sector. However,
ample shear and at least several hundred J/kg of CAPE rooted
just above the boundary layer near the low track may result in a
threat for isolated damaging surface wind gusts or even hail.
In fact, given the elevated nature of storms in the cool sector,
hail may be more of a threat than wind. There is also a very
low/conditional tornado threat, though the focus of that seems
to stay mostly south of our area. Any severe weather threat looks
to peak during the late afternoon and evening hours. Regardless
of any convective threat, a widespread soaking rain of 1 to 2
inches is expected for most of the area, with some isolated
slightly higher or lower totals possible. Recent dry conditions
should preclude a more widespread or significant flood threat,
though isolated nuisance instances of flooding are possible.

[Kmlwx]

I'll watch it with one eye for now. Not too shabby for March. 

[high risk]

8 hours ago, yoda said:

Well hmmm -- from this afternoon's LWX AFD re the chance of some storms

@high risk @Kmlwx

 

 

         I'm totally out on this one.     Honestly, I'm not sure that discussion makes sense unless they're talking about the very southern part of the CWA.    We do not get anything close to SVR here from elevated storms above a stable boundary layer.      I'll consider it a big win if I hear thunder Thursday evening.

[yoda]

Day 1 OTLK has 5% hail reach DC metro and south and southwest down into i81 corridor 

[yoda]

So Friday maybe?

[Eskimo Joe]

On 3/21/2021 at 5:12 AM, yoda said:

So Friday maybe?

South of I-66? Yea maybe.

[yoda]

2 hours ago, Eskimo Joe said:

South of I-66? Yea maybe.

Hopefully the EURO is right over the GFS

...Day 5/Fri - Southeast to Mid-Atlantic...

   Timing and intensity differences continue with respect to the upper
   shortwave trough and surface features on Day 5/Fri. This will impact
   severe potential from parts of the FL Panhandle into southern GA and
   the SC/NC/VA Piedmont vicinity. Some severe potential will exist,
   but confidence is low. The ECMWF maintains a negatively tilted,
   compact shortwave trough lifting northeast from the OH Valley into
   the Northeast, while the surface cold front shifts east of the
   Appalachians during/just after peak heating. Meanwhile the GFS is
   much faster and lower-amplitude, resulting in poorly aligned
   thermodynamics and kinematics. While some severe threat is possible,
   confidence is too low to include probabilities at this time.

[Eskimo Joe]

Yea this time of year, we need a bit of a negative tilt and more robust southerly winds to really scour out the low level wedge. Once we get into late April it's not that big of a deal.

[yoda]

re Friday's chance from this afternoon's LWX AFD

A potent shortwave will eject from the base of a much broader large
scale trough over the western US late Thursday, tracking from Texas
toward the Great Lakes states by Friday. In response, a compact area
of low pressure will develop over the Lower Mississippi Valley and
rapidly deepen as it tracks toward the Great Lakes. There`s still
some spread with respect to the timing of the system, but it appears
as though the system`s cold front will move through the area
sometime during the day on Friday. Much of the large scale forcing
for ascent associated with the very compact shortwave is expected to
pass off to our northwest, so it isn`t expected to be a big
rainmaker for our region. However, the wind field associated with
this dynamic system will be very impressive. Nearly all guidance
shows a 60 plus knot low-level jet developing at 850 hPa, with jet
level winds increasing to over 120 knots. The strong southerly flow
at low levels will transport very warm and moist air into the region
by late-March standards. If the front holds off until later in the
day, many spots will likely make a run at 80 degrees, while
dewpoints surge into the 60s. With the warm/humid airmass in place
at lower levels, at least some surface based instability is expected
to develop in advance of the front (various model guidance shows
somewhere between 100 and 1000 J/kg of CAPE). With the highly
sheared, unstable airmass in place, at least a conditional threat
for severe thunderstorms exists on Friday. However, the timing of
the front, and overall coverage of storms are complicating factors.
If the front moves through early in the day, not much instability
will be able to develop in advance of it. Also, large scale forcing
for ascent is progged to be weak, and convergence even along the
surface front itself is modeled to be rather weak. So in either of
those circumstances, it`s entirely plausible that there aren`t any
storms and it`s just a warm and windy day. Regardless of whether or
not there are storms, gusty winds from the strong background flow
are expected across the area.

[Kmlwx]

That discussion does a good job of summarizing the potential outcomes. Anything from nothing to some severe weather. Covers all the bases  

[vastateofmind]

2 hours ago, Kmlwx said:

That discussion does a good job of summarizing the potential outcomes. Anything from nothing to some severe weather. Covers all the bases  

Well, if nothing else, it sort of illustrates how we do potential severe at least as tentatively as our often overly-complex, thread-the-needle winter storm setups...   

And at the end of the day on Friday, I'll embrace warm/windy as much as I will our first rumble of thunder!

[Kmlwx]

Worth reminding the less frequent severe posters - it is still VERY early for our severe season. Anything this early is usually bonus gravy (sort of like November accumulating snow). April is even a bit early but can definitely have some beefier setups. May/June can be what either makes or breaks our severe weather season as a whole. 

[yoda]

00z NAM at range ofc... but shear is through the roof at 12z FRI -- but no SBCAPE as of yet since its morning lol.   ML Lapse Rates are near 7.0 C/KM too

[yoda]

First mention of Thursday night/Friday severe chance in the HWO (damaging winds)

And thunderstorms are now in the zones

[nj2va]

I need a good 101 type site/etc re: how to read a sounding for thunderstorms.  Anyone have a good reference?  

[vastateofmind]

1 hour ago, nj2va said:

I need a good 101 type site/etc re: how to read a sounding for thunderstorms.  Anyone have a good reference?  

I should practice sounding reads more often, as I still find them confusing. However, these are three resources I've held onto in recent years, ranked in terms of increasing complexity. Last one in particular from weather.gov provides some great examples. Others posting here likely have even better links/resources than this.

Green Sky Chaser » Meteorology 101: Atmospheric Sounding Charts

Atmospheric Soundings - An Introduction - Weatherwatch

Skew-T Parameters and Indices (weather.gov)

[Eskimo Joe]

On 3/17/2021 at 12:12 PM, George BM said:

45% TOR area added now.

 

[Kmlwx]

The NAM is too fast for Friday as well. Would be too early in the day to maximize heating. 

[nj2va]

11 hours ago, vastateofmind said:

I should practice sounding reads more often, as I still find them confusing. However, these are three resources I've held onto in recent years, ranked in terms of increasing complexity. Last one in particular from weather.gov provides some great examples. Others posting here likely have even better links/resources than this.

Green Sky Chaser » Meteorology 101: Atmospheric Sounding Charts

Atmospheric Soundings - An Introduction - Weatherwatch

Skew-T Parameters and Indices (weather.gov)

Thanks for these.  I was really hoping to find a resource to explain how to read CAPE, etc on skew t for severe season.  I did a little googling tonight and found this resource - I’ll need to spend some time on this site as its more complicated than I expected, ha.  It’s well laid out though on here!

http://thevane.gawker.com/nerdin-it-up-how-to-find-instability-by-hand-on-a-skew-1706378907

[Kmlwx]

Looks as if we will keep waiting. Not much of anything of interest on the long range GFS either. Not surprised - but we'll see what April brings. 

[yoda]

Maybe a stray STW late tonight?

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1034 AM EDT Thu Mar 25 2021


.NEAR TERM /THROUGH TONIGHT/...
For the most part, areas of dense fog has burned off or
deteriorated, except for parts of the Virginia Piedmont.
Visibility remains near or below one-quarter mile in Orange,
Albemarle and Nelson Counties. We should see visibility reach
one mile or more in these areas by 11am.

Low pressure, currently over Arkansas, will move into the
eastern Great Lakes by tonight. Ahead of this low, a developing
southerly flow will bring milder and moist air northward into
our region. A strong cold front will develop in association
with this low and push towards the region this evening. High
temperatures will reach near 70 to perhaps the middle 70s in
places that encounter more sunshine.

There will be some showers and perhaps a few thunderstorms in
the western half of our CWA tonight into Friday morning ahead
of the cold front. In coordination with SPC, we have up the
possibility of damaging thunderstorms from a General Risk to a
Marginal Risk along and to the west of the Blue Ridge for the
nighttime hours, primarily after midnight. Low temperatures
tonight remain in the low 60s with strong southerly flow
developing.

[Eskimo Joe]

13 minutes ago, yoda said:

Maybe a stray STW late tonight?

IMO, seems like whenever we get these robust Dixie / Carolina Alley events, something usually slips up into NOVA and surprises everyone.

[George BM]

Ah, great to see the weather.cod.edu site taking a lunch break now. 

[NorthArlington101]

Just bought GRLevel3. Life changed. Ready for severe season with the dual monitor setup. 

[vastateofmind]

55 minutes ago, NorthArlington101 said:

Just bought GRLevel3. Life changed. Ready for severe season with the dual monitor setup. 

Had to Google it cuz I didn't know what it was. Looks like it could be an impressive AND fun product. Do you think it's worth the asking price?

[NorthArlington101]

Had to Google it cuz I didn't know what it was. Looks like it could be an impressive AND fun product. Do you think it's worth the asking price?

I’m hoping so, haha. I’ve only been fiddling around with it for 45 minutes but it seems very useful, especially for a desktop radar. Something about RadarScope’s radar still looks more visually appealing to me but I’m trying to shift the GRLevel3 radars to use the same color table.

Looks like there is also cool GIS stuff to be done with GRLevel3. Lots of potential fun to be had. I’m excited to own it.

[vastateofmind]

9 minutes ago, NorthArlington101 said:

I’m hoping so, haha. I’ve only been fiddling around with it for 45 minutes but it seems very useful, especially for a desktop radar. Something about RadarScope’s radar still looks more visually appealing to me but I’m trying to shift the GRLevel3 radars to use the same color table.

Looks like there is also cool GIS stuff to be done with GRLevel3. Lots of potential fun to be had. I’m excited to own it.

Great reminder about Radarscope -- I'm going to pull the trigger on that today or tomorrow. Have been meaning to buy it for the past year or two for my phone, but always found other apps to waste money on.

[NorthArlington101]

43 minutes ago, vastateofmind said:

Great reminder about Radarscope -- I'm going to pull the trigger on that today or tomorrow. Have been meaning to buy it for the past year or two for my phone, but always found other apps to waste money on.

Radarscope is a must. Top 10 purchases of my life, probably.