2019 Mid-Atlantic Severe Wx - General Discussion

[Eskimo Joe]

4 minutes ago, yoda said:

The line in WV moving east and northeast is currently being warned for winds to 70mph

Several reports 70+.  Impressive.

[yoda]

6 minutes ago, Eskimo Joe said:

Several reports 70+.  Impressive.

I'm guessing that will be the line we will be waiting for in the next two hours or so 

[Eskimo Joe]

Just now, yoda said:

I'm guessing that will be the line we will be waiting for in the next two hours or so 

Yup...winds picking up here ahead of it in Baltimore.  Feels great outside.

[Kmlwx]

5 minutes ago, yoda said:

I'm guessing that will be the line we will be waiting for in the next two hours or so 

So are we now looking a bit earlier than the earlier thoughts of like 2-4am? 

[janetjanet998]

00z RUC and HRRR models actually increase instabily the next few hours...perhaps from cooling aloft ....

HRRR also breaks out cells ahead of the line.....as mentioned by SPC 

[yoda]

12 minutes ago, Kmlwx said:

So are we now looking a bit earlier than the earlier thoughts of like 2-4am? 

I was guessing two hours from where the line was... it could be more.  The line was beginning to move more NE than E

[yoda]

920pm LWX AFD update:

NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Initial round of discrete cells has moved through the area. Some
scattered showers and storms will remain possible the next few
hours, but overall we will be in a lull until the line
stretching through West Virginia reaches us. The 00Z IAD
sounding sampled the environment which contains very strong
shear but limited instability. Even though the storms so far had
a strong disconnect with the lowest levels, the environment
continues to modify due to a strong low level jet and moisture
advection despite it being after dark. Models continue to
indicate CAPE will actually increase the next several hours
ahead of the approaching line. One clue to the overall severity
may be the strength of surface wind gusts. So far they have been
fairly limited, but if they increase, that could be an indicator
strong winds may have an easier time making it to the surface.
Severe level winds have been observed with bowing segments in
West Virginia. Any bulges in the line which orient into a
northeasterly direction could produce a tornado as well (more
favorable orientation to low level shear). It`s important not to
let complacency build with the lull the evening and the lack of
severe weather so far...residents should have a way to receive
weather warnings overnight. Would expect the threat to ramp up
between 10-11 PM along the Appalachians, and reach the I-95
corridor around 2-3 AM. It`s a little uncertain if the initial
line stays in tact the whole way across, or if it breaks up and
new convection develops in the more favorable environment
near/east of the Blue Ridge.

[yoda]

Trees and wires blown down in Greenbrier County in WV per LWX SWS

[Amped]

HRRR wants discrete cells, 3km NAM ants to keep a line.   We'll see whose right.

[Eskimo Joe]

11 minutes ago, Amped said:

HRRR wants discrete cells, 3km NAM ants to keep a line.   We'll see whose right.

I'd side with the 3k nam.  HRRR is.....a thing.

[09-10 analogy]

Discrete cells overnight in April ... I dunno, that seems it would be rather ... anomalous for our region. 

[southmdwatcher]

Sorry for the delete, new tornado watch for western VA(south of CHO) and western half of NC  down to the upstate of SC until 5am. Delayed timing for the southern half of our area??

[southmdwatcher]

6 minutes ago, 09-10 analogy said:

Discrete cells overnight in April ... I dunno, that seems it would be rather ... anomalous for our region. 

Don't know if they make it north of I64, but there are more than a few bands and discrete cells developing across SW VA in the new tornado watch area, heading NE.

[yoda]

Is there a storm out by Middleburg?  Radarscope had a rotation marker out there and what looks to be a few lightning strike markers too

[yoda]

I'd start watching the storms in SW VA... looks like things are moving more NEward now... some storms are firing

ETA: and just as I post that... STW pops up just east of LYH... that's the one to watch IMO as it heads NE

[yoda]

Def looks like there is some rotation down by Appomattox?  Or am I wrong?

[southmdwatcher]

The SPC mesoscale page has a relatively new Beta parameter, the Violent Tornado parameter. It has been fairly accurate with the significant tornadoes so far this season. The large bullseye in central NC that ramped up over the past few hours to a level of 15, needs to pass south and east of us or diminish just as quickly as it ramped up. I believe it may pass through the eastern side of our forecast area in a few hours.

 

 

 

[southmdwatcher]

Well, it is certainly a good thing that we did not have any further elevated levels of instability earlier to aid these storms. The line across the Appalachians is breaking up somewhat into segments and discrete storms and segments are dominant east of the Blue Ridge from here south to the Carolina's.

[yoda]

@wasnow215 Tornado watch coming for you soon per SPC MCD just issued 

[Amped]

RDU radar looks bizzare

[southmdwatcher]

New tornado watch incoming for central and eastern VA downstream from the eastern side of our area.

 

Mesoscale Discussion 0359
NWS Storm Prediction Center Norman OK
1107 PM CDT Sun Apr 14 2019

Areas affected...Southeast Virginia and northern North Carolina

Concerning...Severe potential...Watch likely 

Valid 150407Z - 150600Z

Probability of Watch Issuance...80 percent

SUMMARY...A gradual increase in storm coverage and intensity is
expected. A tornado watch is likely.

DISCUSSION...Numerous showers have developed in central North
Carolina within the last hour on the western edge of a higher
theta-e airmass in eastern North Carolina and Virginia. These 70+
degree dewpoints are expected to continue to advect northwestward
which will aid in destabilization across the area as temperatures
cool aloft. The updrafts currently lack deep growth amid strong
shear, but are expected to slowly deepen and eventually reach severe
strength in the next 1 to 2 hours as the instability increases and
the low-level jet strengthens (~70 knots per RAX VWP). Effective
shear in excess of 60 knots will support supercell storm mode with a
risk for damaging winds and isolated tornadoes. Directional shear is
not all that strong, but 0 to 1 km speed shear in excess of 50 knots
may support some low-level mesocyclone organization.

..Bentley.. 04/15/2019
 

[wasnow215]

1 minute ago, southmdwatcher said:

Well, it is certainly a good thing that we did not have any further elevated levels of instability earlier to aid these storms. The line across the Appalachians is breaking up somewhat into segments and discrete storms and segments are dominant east of the Blue Ridge from here south to the Carolina's.

So you think short term weather models are wrong showing redevelopment?

[southmdwatcher]

2 minutes ago, wasnow215 said:

So you think short term weather models are wrong showing redevelopment?

Not at all, that is certainly underway across central and western VA and NC. 

 

[yoda]

Just now, southmdwatcher said:

Not at all, that is certainly underway across western VA and NC. 

 

So looks like HRRR wins over 3km NAM 

[yoda]

Rotation marker on the Appomattox storm on radarscope 

[wasnow215]

1 minute ago, yoda said:

So looks like HRRR wins over 3km NAM 

How so? You think more spotty and mainly east of 95?

[yoda]

Just now, wasnow215 said:

How so? You think more spotty and mainly east of 95?

3km NAM had more of a line sweeping in from the west... HRRR had more of a "discrete storm" picture IMO

[NorthArlington101]

Rotation marker on the Appomattox storm on radarscope 

Due north of Pamplin City looked interesting for a frame or two.

[yoda]

2 minutes ago, NorthArlington101 said:

 

Due north of Pamplin City looked interesting for a frame or two.

 

It did... is it the outer range of the LWX radar that Lexington has so much red and green combined?

[southmdwatcher]

Ugh, the bands coming out of NC are looking to set up a train. Along with the significant parameters for severe. We get a taste of Dixie Alley tonight, hopefully without any pain.