2023 Mid-Atlantic Severe Wx Thread (General Discussion)

[Eskimo Joe]

Radar got busy fast. Stalled fronts can be fun!

[87storms]

Radar got busy fast. Stalled fronts can be fun!

Yesterday gets a pass, but I prob only got about 0.2” total. Still seems like the rich are getting richer, but hoping to cash in by this evening assuming there’s enough instability leftover (the trough moving further east should help).

[09-10 analogy]

Potent storm rolling through right now. Couple close CG strikes, winds over 40. I'd say it's the second or third most rambunctious storm of the season. 

[batmanbrad]

NWS thinking highly enough of the repeating storm possibilities to hoist a flood watch for parts of our area.  Must think there could be a lot of heavy rain considering the fairly dry antecedent conditions.

[SnowenOutThere]

Best severe weather day of the season with the latest storm, got a decent amount of pea size hail and some pretty intense gusts with it. Think it was a somewhat localized microburst overhead, either way the rain was needed. 

[Rhino16]

Missed the heaviest rain in blacksburg, but down near the stadium has had 4” or more and flooding occurred. Guessing I have half that despite being only a mile and a half away.

Also: poor planning for the game.

[NorthArlington101]

Missed the heaviest rain in blacksburg, but down near the stadium has had 4” or more and flooding occurred. Guessing I have half that despite being only a mile and a half away.
Also: poor planning for the game.

Bad day for ACC football. Hoping UVA’s delay ends shortly. Getting folks in and out of the stadium when it storms is a massive mess.

[87storms]

I think this is the first time all season…maybe even all year…that I’m getting what appears to be a train of precip. I’m sure it’ll rain itself out, but this is a good soaker in progress. Little bit of thunder mixed in as well.

[Wxtrix]

an outflow boundary is coming through—the house is making a lot of noise.

[09-10 analogy]

2 hours ago, SnowenOutThere said:

Best severe weather day of the season with the latest storm, got a decent amount of pea size hail and some pretty intense gusts with it. Think it was a somewhat localized microburst overhead, either way the rain was needed. 

Yeah I got that impression too: that there was a lot of wind energy off the surface. The sound of the wind - very loud — didn’t seemed to correspond to the swaying of the trees, which is what I made my guesstimate of 40+ from. From how loud the wind sounded it seemed like there would have been more action at the surface. Branches down, that kind of thing. Of course this could be — and probably is — all my imagination, without any validity at all. 

[midatlanticweather]

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Baltimore MD/Washington DC
1156 PM EDT Tue Sep 12 2023

The National Weather Service in Sterling Virginia has issued a

* Tornado Warning for...
  Central Harford County in northern Maryland...
  East central Baltimore County in northern Maryland...

* Until 1230 AM EDT.

* At 1155 PM EDT, a severe thunderstorm capable of producing a
  tornado was located over Perry Hall, or near Middle River, moving
  northeast at 20 mph.

  HAZARD...Tornado and quarter size hail.

  SOURCE...Radar indicated rotation.

  IMPACT...For those in the direct path of a tornado touchdown,
           flying debris will be dangerous to those caught without
           shelter. Damage to roofs, siding, and windows may occur.
           Mobile homes may be damaged or destroyed. Tree damage is
           likely.

* This dangerous storm will be near...
  Bel Air South, Bel Air North, Fallston, Kingsville, and Pleasant
  Hills around 1200 AM EDT.
  Riverside and Perryman around 1205 AM EDT.

Other locations impacted by this tornadic thunderstorm include
Nottingham, Edgewood, Fork, Benson, Magnolia, Bradshaw, Bynum,
Joppatowne, Abingdon, and Joppa.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

[midatlanticweather]

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Mount Holly NJ
1225 AM EDT Wed Sep 13 2023

The National Weather Service in Mount Holly NJ has issued a

* Tornado Warning for...
  Northeastern Talbot County in eastern Maryland...
  South central Queen Anne`s County in northeastern Maryland...

* Until 100 AM EDT.

* At 1224 AM EDT, a severe thunderstorm capable of producing a
  tornado was located over Copperville, or 7 miles northwest of
  Easton, moving northeast at 20 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

* Locations impacted include...
  Easton, Matthews, Skipton, Wye Mills, Copperville and Cordova.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Tornadoes are extremely difficult to see and confirm at night. Do not
wait to see or hear the tornado. TAKE COVER NOW!

To report severe weather contact your nearest law enforcement agency.
They will send your report to the National Weather Service office in
Mount Holly NJ.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

[AlexD1990]

Now a tornado warning on the eastern shore

Sent from my SM-F711U using Tapatalk

[Eskimo Joe]

Going to put this here since it is relevant to severe weather. I'm in Albany, NY this week for the NY State mesonet symposium. Several talks have focused on HRRR verification against the state mesonet sites and ASOS sites. Couple of conclusions that have come up over and over again regarding the HRRR:

1.) The HRRR systematically overpredicts surface winds.

2.) The HRRR performs poorly with initiating boundary layer clouds (cumulus) in days following air mass changes during June, July, August.

3.) The HRRR clearly overmixes the boundary layer, especially in SW flow events, and drops the surface dewpoint too quickly. This causes Surface Based CAPE (SBCAPE) to be between modeled 250-750 j/kg SBCAPE too low.

4.) The HRRR is too quick to mix out low level temperature inversions (The Wedge™ ) during spring convective events.

[mappy]

Fun! Glad you were able to go to that!

 

Also, for anyone who may be interested in the Mid-Atlantic Severe Conference in Richmond in early November, I am going to go!  

[Eskimo Joe]

Some additional tidbits for severe weather. Please note these are conclusions from various presentations and not my own thoughts.

1.) Mesonets that capture solar irradiance (W/m^2) should visualize their data. Gradients in solar irradiance can illustrate CAPE gradients that will support convective initiation. NOTE: The Maryland mesonet will show this once stations are deployed.

2.) The SPC HREF performs poorly with mid level cloud erosion times in cool weather severe episodes, especially in the Mid Atlantic and Northeast. The cause remains unknown and warrants further study. If the SPC HREF shows an area breaking out into the warm sector, and does not have support from the rest of the CAMS, consider disregarding the SPC HREF.

3.) When forecasting big hail events, the 12z RAOB closest to your location can be helpful in identifying an EML. This is especially true when comparing to special 18z RAOB because the 12z data will feature a comparatively cool surface temperature which lets a forecaster "see" the fingerprint of an EML advecting from Texas or the Mexico highlands.

[MN Transplant]

4 hours ago, Eskimo Joe said:

Some additional tidbits for severe weather. Please note these are conclusions from various presentations and not my own thoughts.

1.) Mesonets that capture solar irradiance (W/m^2) should visualize their data. Gradients in solar irradiance can illustrate CAPE gradients that will support convective initiation. NOTE: The Maryland mesonet will show this once stations are deployed.

2.) The SPC HREF performs poorly with mid level cloud erosion times in cool weather severe episodes, especially in the Mid Atlantic and Northeast. The cause remains unknown and warrants further study. If the SPC HREF shows an area breaking out into the warm sector, and does not have support from the rest of the CAMS, consider disregarding the SPC HREF.

3.) When forecasting big hail events, the 12z RAOB closest to your location can be helpful in identifying an EML. This is especially true when comparing to special 18z RAOB because the 12z data will feature a comparatively cool surface temperature which lets a forecaster "see" the fingerprint of an EML advecting from Texas or the Mexico highlands.

The averaging period will be important for solar irradiance.

[Eskimo Joe]

More highlights tomorrow folks!

[TSG]

6 hours ago, Eskimo Joe said:

Some additional tidbits for severe weather. Please note these are conclusions from various presentations and not my own thoughts.

1.) Mesonets that capture solar irradiance (W/m^2) should visualize their data. Gradients in solar irradiance can illustrate CAPE gradients that will support convective initiation. NOTE: The Maryland mesonet will show this once stations are deployed.

2.) The SPC HREF performs poorly with mid level cloud erosion times in cool weather severe episodes, especially in the Mid Atlantic and Northeast. The cause remains unknown and warrants further study. If the SPC HREF shows an area breaking out into the warm sector, and does not have support from the rest of the CAMS, consider disregarding the SPC HREF.

3.) When forecasting big hail events, the 12z RAOB closest to your location can be helpful in identifying an EML. This is especially true when comparing to special 18z RAOB because the 12z data will feature a comparatively cool surface temperature which lets a forecaster "see" the fingerprint of an EML advecting from Texas or the Mexico highlands.

As an engineer in the solar industry, #1 has me breathing heavy

[Eskimo Joe]

1 hour ago, TSG said:

As an engineer in the solar industry, #1 has me breathing heavy

A lot of mesonets are supporting the solar and wind industries without knowing it.

[TSG]

12 hours ago, Eskimo Joe said:

A lot of mesonets are supporting the solar and wind industries without knowing it.

Do you have any visibility into what the equipment spec is? Is it a pyranometer? reference cell?

[Rhino16]

On 9/13/2023 at 1:53 PM, mappy said:

Fun! Glad you were able to go to that!

 

Also, for anyone who may be interested in the Mid-Atlantic Severe Conference in Richmond in early November, I am going to go!  

VT’s Met club will have a table there so I’ll probably go home for that!

[high risk]

On 9/13/2023 at 2:18 PM, Eskimo Joe said:

Some additional tidbits for severe weather. Please note these are conclusions from various presentations and not my own thoughts.

1.) Mesonets that capture solar irradiance (W/m^2) should visualize their data. Gradients in solar irradiance can illustrate CAPE gradients that will support convective initiation. NOTE: The Maryland mesonet will show this once stations are deployed.

2.) The SPC HREF performs poorly with mid level cloud erosion times in cool weather severe episodes, especially in the Mid Atlantic and Northeast. The cause remains unknown and warrants further study. If the SPC HREF shows an area breaking out into the warm sector, and does not have support from the rest of the CAMS, consider disregarding the SPC HREF.

3.) When forecasting big hail events, the 12z RAOB closest to your location can be helpful in identifying an EML. This is especially true when comparing to special 18z RAOB because the 12z data will feature a comparatively cool surface temperature which lets a forecaster "see" the fingerprint of an EML advecting from Texas or the Mexico highlands.

 

     Realizing that you're just sharing info, I don't understand #2.   The HREF is just means and probabilities generated from all of the operational CAMs.    So, it can't be dramatically different from its inputs.

[Kmlwx]

Pencil thin convective potential on Sunday? GFS gets marginal supercell composite parameters into the area. Nothing super severe - but could be a bit of "interesting" weather more than just fog and rain and sun. 

[George BM]

18 minutes ago, Kmlwx said:

Pencil thin convective potential on Sunday? GFS gets marginal supercell composite parameters into the area. Nothing super severe - but could be a bit of "interesting" weather more than just fog and rain and sun. 

A MRGL wouldn't surprise me if wind fields are strong enough and the pencil thin-line can tap into that wind aloft.

[Kmlwx]

24 minutes ago, George BM said:

A MRGL wouldn't surprise me if wind fields are strong enough and the pencil thin-line can tap into that wind aloft.

If nothing else - 925mb and 850mb winds are pretty impressive for a time on Sunday. GFS has 45-55mph gusts. Would at least trigger a wind advisory if that verifies.