2022 Mid-Atlantic Severe Wx Thread (General Discussion Etc)

[poolz1]

A pretty wild scene here yesterday.  Just under 2" but just a mile or two south had to be close to 4".

On the deck watching the creek rage and started hearing loud snaps.  Saw the top of a massive sycamore start to shake and called the family out.  Finally, a loud crack and we watched the tree crash.

Im pretty proficient with a chainsaw but the rootball on this tree makes me nervous. At some point it is going to want to stand back up and I sure as hell don't want to be standing beside the tree when that happens. The pic doesn't do justice. Rootball is about 20' wide and 12' tall.

 

[mattie g]

Might have to fire up the drought thread. Ground is pretty hard in these parts.

[Stormfly]

2 hours ago, poolz1 said:

A pretty wild scene here yesterday.  Just under 2" but just a mile or two south had to be close to 4".

On the deck watching the creek rage and started hearing loud snaps.  Saw the top of a massive sycamore start to shake and called the family out.  Finally, a loud crack and we watched the tree crash.

Im pretty proficient with a chainsaw but the rootball on this tree makes me nervous. At some point it is going to want to stand back up and I sure as hell don't want to be standing beside the tree when that happens. The pic doesn't do justice. Rootball is about 20' wide and 12' tall.

 

 

That is best tackled by supporting the trunk to the left (only to make it easier for buck cuts) and cut near the base and let the root ball swing to the right of your kerf.  Make sure the ground has had time to dry up so you have good footing!

[yoda]

That was a pretty tasty afternoon AFD 

[poolz1]

That is best tackled by supporting the trunk to the left (only to make it easier for buck cuts) and cut near the base and let the root ball swing to the right of your kerf.  Make sure the ground has had time to dry up so you have good footing!

I hear ya and sounds reasonable. To be honest, the more I look at this thing the more I see myself getting the catapult into the neighbors yard! Lol. We have friends that have a tree removal business. I may leave this one to the professionals.

[Stormfly]

10 minutes ago, poolz1 said:

I hear ya and sounds reasonable. To be honest, the more I look at this thing the more I see myself getting the catapult into the neighbors yard! Lol. We have friends that have a tree removal business. I may leave this one to the professionals.

Yes that is a good idea.  Tree work is something you don't want to get involved with and realize the job was beyond your abilities!  Definitely the safe way to go.

[Eskimo Joe]

17 hours ago, Kmlwx said:

Major outage in Eastern MoCo and western PGCO. Been out since around 2am. Generator picked a great night to fail.... 

Must be a big transmission line or substation. Usually those get isolated quick... No such luck this time. Seems over 20K are impacted. 

Was a substation.

[yoda]

12z HRRR was... interesting for tomorrow afternoon 

12z NAM NEST isn't bad either for both Tuesday and Wednesday afternoon/evening 

09z RAP at distance is also decent

[yoda]

Good discussion by LWX in their afternoon AFD regarding tomorrow afternoon 

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...

A warm front is expected to slowly lift northward through the region
late this evening and into Tuesday. An upper level ridge will be in
place over the upper plains with weak troughing over the eastern US
on Tuesday. As the warm front lifts northward through the region on
Tuesday, a southerly flow is expected to form leading to increased
advection of warm and moist air into the region. The orientation of
upper level ridge over the upper plains will place our region in a
favorable location for shortwave energy to pass over the ridge and
drop down into our region. Model guidance has continued to indicate
that CAPE values will be well above 2000 j/kg with shear progged to
be between 30 and 40 knots. Multiple waves/shortwaves moving along
the boundary may lead to multiple waves of thunderstorms during the
afternoon periods on Tuesday.



HiRes guidance continues to differ about the threat for severe
weather on Tuesday especially on the overall coverage of storms.
Based on the environmental setup, any storms that do form will
likely become strong to severe and potentially produce damaging
winds, large hail and an isolated tornado. A westerly flow at 850mb
could affect storm coverage and mean the difference between bowing
segments and isolated supercells.  We will need to monitor upstream
activity which could affect the initiation of storms over our
region. Model guidance may not come into good agreement until later
this evening and we will need to monitor HiRes guidance to determine
overall SVR threat, whether it be bowing segments or super cells or
a minimum threats. A westerly orographic enhanced flow along with
multiple shortwaves could lead to enhanced precipitation along the
western Alleghenies and flooding.

[CAPE]

Latest from Mount Holly-

Attention in the near term remains on the potential for severe thunderstorms in the area during the day on Tuesday. There remains a good bit of uncertainty on the timing and progression of the aforementioned remnant convection from upstream across the southern Great Lakes and Ohio Valley regions. The timing and track of these remnants will determine if we get any new convection developing and moving into our area, and if so, the degree of the intensity and coverage of the storms. The latest suite of CAM guidance suggests a consensus favoring severe convection developing in the early afternoon to our west across the Pennsylvania Capital Region and southwest into central Maryland and northern Virgina then moving east and impacting the southern half of the forecast area. This consensus will almost certainly change in future runs though depending on the progression of the upstream convection once any complexes begin to mature. In any case, if storms do develop and move through our area during a favorable time in the afternoon to evening, severe thunderstorms would be probable given the environment in place. Deep layer effective shear around 40 kts, MLCAPE in the 1,000-2,000 J/kg range, and effective SRH near 200 m2/s2 will be in play if we have enough time to destabilize. If an initial round moves through the area early enough in the day, a second round could be possible later in the afternoon or evening as well.

[Kmlwx]

18z NAM nest sucks. It's essentially nothing other than some scattered gusty showers - and almost nothing in DC proper.

[George BM]

50 minutes ago, Kmlwx said:

18z NAM nest sucks. It's essentially nothing other than some scattered gusty showers - and almost nothing in DC proper.

Not that it means much but the funny thing (to me at least) is that the usually 'CAPE-happy' 3kmNAM is anemic with instability through the early/mid afternoon while the usually 'Eeyore-instability' HRRR has fairly decent CAPE during that same time period.

[Kmlwx]

31 minutes ago, George BM said:

Not that it means much but the funny thing (to me at least) is that the usually 'CAPE-happy' 3kmNAM is anemic with instability through the early/mid afternoon while the usually 'Eeyore-instability' HRRR has fairly decent CAPE during that same time period.

It seems like the 3km NAM keeps moisture return kind of anemic

[yoda]

FWIW, 21z RAP sim radar looks good... squall line crests Apps around 17z... reaches i95 corridor around 19z tomorrow afternoon

18z HRRR looks decent for tomorrow too around 19z

[yoda]

23z HRRR has a line setting up at the end of its run (17z TUE) in Western PA with what looks to be embedded sups (I think... could just be intense portion of the line forming) and storms initiating in the i81 corridor

[Kmlwx]

Both the runs @yodamentioned look solid

[yoda]

2 minutes ago, Kmlwx said:

Both the runs @yodamentioned look solid

I am gathering we are watching the area where SPC just issued a STWatch, correct?  The IA/IL/IN area?

[yoda]

Looks like 00z HRRR is trying to develop some discrete activity ahead of the bow echo/line at 18z/19z

[Kmlwx]

4 minutes ago, yoda said:

I am gathering we are watching the area where SPC just issued a STWatch, correct?  The IA/IL/IN area?

I haven't caught up with tracking today yet

[yoda]

7 minutes ago, yoda said:

Looks like 00z HRRR is trying to develop some discrete activity ahead of the bow echo/line at 18z/19z

Its almost like it breaks up the line into supercells as it enters MD/N VA/DC by 20z

[Kmlwx]

34 minutes ago, yoda said:

Its almost like it breaks up the line into supercells as it enters MD/N VA/DC by 20z

Looks like the line misses us and that stuff is discrete activity that develops ahead

[CAPE]

Nice AFD from Mount Holly-

We continue to monitor the potential for severe weather this afternoon and evening. As is usually the case in northwest flow patterns, the severe weather potential today is highly uncertain. Most pressingly, it`s not clear what the forcing mechanism for convection would be. While the MCS to our west this morning probably won`t impact us with severe weather, it`s possible new cells could develop on its outflow. We will also have a cold front approaching by late today or tonight. This could also lead to convective development, but it`s not a very strong front and the column aloft also starts to become drier with time this evening. PoPs for the next 24 hours were derived from a broad-based blend of global and CAM guidance. They generally maximize at chance to likely values, and are highest from late afternoon through mid to late evening.

In a probabilistic sense, the most likely scenario appears to be that we get little if any in the way of severe weather today. It doesn`t seem likely that our moisture levels will recover in time to generate significant surface based instability, not to mention the cloud cover potentially keeping temperatures down. Lack of instability will be a big inhibitor considering the nebulous forcing. Most guidance does indicate a ribbon of some instability developing by late today over portions of Delmarva and east-central Pennsylvania, in the neighborhood of 500 to 1000 J/kg of SBCAPE. But with poor mid-level lapse rates and drier air advecting in aloft, it will be difficult to sustain robust updrafts in that sort of environment. The shear profiles are certainly interesting though, between the rather backed surface winds and strong mid-level flow. Should any sustained deep convective cells develop, which would be more likely if instability ends up greater than forecast, then there would be a threat for damaging winds and perhaps a tornado considering impressive SRH values by later today. Will definitely be a day where monitoring real time observations as well as trends in the CAMs is important.

[Kmlwx]

My dewpoint is 63ish this AM. Would like to see that higher for the threat for later. 

[Kmlwx]

Last 3 or so HRRR runs have been quite nice for the metro area this afternoon. 

[AmericanWxFreak]

4 minutes ago, Kmlwx said:

Last 3 or so HRRR runs have been quite nice for the metro area this afternoon. 

Showing more discrete activity like before or is it getting us w the line/bow?

[Kmlwx]

15 minutes ago, AmericanWxFreak said:

Showing more discrete activity like before or is it getting us w the line/bow?

New development but potentially triggered in part by the existing line. Though models tend to do poorly with distinguishing new development from existing line - especially when the lines are blurred. 

[North Balti Zen]

 

[Kmlwx]

Decent amount of cloud cover in the area - but there should be some breaks of sunshine for many at times. 

 

[Kmlwx]

Has the feeling like early activity *might* be an issue. Some stuff just W of Elkins now, and even a shower N of Culpeper. 

[Eskimo Joe]

11 minutes ago, Kmlwx said:

Has the feeling like early activity *might* be an issue. Some stuff just W of Elkins now, and even a shower N of Culpeper. 

Only the HRRR has anything decent for today and it's mostly south of DC. Would argue we all temper our expectations greatly.