2019 Mid-Atlantic Severe Wx - General Discussion

[CAPE]

37 minutes ago, C.A.P.E. said:

Dark skies and rumbling just to my west. Relatively small cell so odds are it will miss. As expected most of the good stuff firing to the south.

Ended up hitting here. Nice 15-20 min downpour with a couple cracks of thunder.

Picked up 0.23". Nice little drink for my parched soil. Weeds were struggling, lol.

[CAPE]

Pretty intense looking line over Dorchester county with a warning.

[yoda]

31 minutes ago, Kmlwx said:

Friday will probably be all about the CAPE. If the CAPE is too low it'll probably be a pencil thin line of gusty showers. 

LWX mentions QLCS and nice low level and deep layer shear

[Kmlwx]

Instability will be the question mark with Friday. Shear should be more than sufficient. Looks like a chance later in the weekend maybe too. (Sunday?)

[yoda]

3 hours ago, Kmlwx said:

Instability will be the question mark with Friday. Shear should be more than sufficient. Looks like a chance later in the weekend maybe too. (Sunday?)

If I am reading it right, 12z CMC says that Sunday afternoon into Sunday night would be a nice severe weather event... 995mb SLP in NE KY at 18z SUN to 991mb SLP in W PA at 00z MON...  Too bad its the CMC lol

[Kmlwx]

Way out there - but the GFS has a decent setup it seems for next Friday...

[yoda]

LWX seems to suggest late Sunday into Sunday night could be a threat for a few severe storms

A southerly flow ahead of the cold front will usher in warm and
humid conditions Sunday. An anomalous amount of moisture will be
in place and this can be seen in the NAEFS and with PWATS
forecasted near the max for this time of year relative to
climatology and over 2 SD above climo as well. Also, the wind
field through all levels of the atmosphere will be strengthening
Sunday as the low passes by well to our west. Therefore, with
the moisture and warm airmass in place, the chances for showers
and thunderstorms will increase Sunday. Still not confident in
coverage because the frontogenetical forcing should remain to
our west Sunday, since guidance has slowed down a bit with the
timing of this system.

The cold front will pass through Sunday night, and this will
increase the chances for showers and perhaps a few
thunderstorms. Confidence remains low this far out, but with the
anomalously moist airmass in place, a strong wind field through
all of the atmosphere, a negatively tilted upper-level trough,
and forcing from the cold front...this does cause a threat for
severe thunderstorms and heavy rain. Again confidence is low,
but the main threat would be damaging wind gusts. Will have to
re-assess as we get closer to the event.

[yoda]

9 minutes ago, Kmlwx said:

Way out there - but the GFS has a decent setup it seems for next Friday...

Looks nice... but its a lill early for our liking as best parameters are around noon

[Kmlwx]

3 minutes ago, yoda said:

Looks nice... but its a lill early for our liking as best parameters are around noon

Luckily it's 8 days away. 

[yoda]

LWX seems to still like late Sunday into Sunday night for some possible severe 

[yoda]

SPC day 1 OTLK has marginal risk for good amount of the LWX CWA... 5% hail and 5% wind

[Kmlwx]

LWX in their early AM discussion seems very bullish despite them also mentioning uncertainty for late next week. Too far out to say anything for now. 

[Kmlwx]

The 12z 12km NAM also looks kind of good for overnight Sunday into Monday...but we all know how nocturnal stuff usually works for us. Unless that speeds up to be Sunday afternoon it probably won't be much. 

[yoda]

1 hour ago, Kmlwx said:

The 12z 12km NAM also looks kind of good for overnight Sunday into Monday...but we all know how nocturnal stuff usually works for us. Unless that speeds up to be Sunday afternoon it probably won't be much. 

HWO does mention risk... even states an isolated tornado cannot be ruled out due to hodograph

12z NAM seems to also have two distinct "threat" periods... one around 00z and one around 09z looking at the soundings

[high risk]

3 hours ago, Kmlwx said:

The 12z 12km NAM also looks kind of good for overnight Sunday into Monday...but we all know how nocturnal stuff usually works for us. Unless that speeds up to be Sunday afternoon it probably won't be much. 

               The overnight threat Sunday could materialize better than overnight threats usually do here if the NAM is correct.   It shows strong southerly winds keeping temperatures here in the upper 60s through the night.

 

[Kmlwx]

23 minutes ago, high risk said:

               The overnight threat Sunday could materialize better than overnight threats usually do here if the NAM is correct.   It shows strong southerly winds keeping temperatures here in the upper 60s through the night.

 

Would be a fun night if that were to verify. 

[yoda]

1 hour ago, Kmlwx said:

Would be a fun night if that were to verify. 

Afternoon AFD from LWX seems to hint at that:

The front will stall south of the area Sat with the majority of
the shra activity remaining to the south of our CWA. Any showers
will likely depend on areas that receive the most heating.
Otherwise, expect plenty of mid-high level clouds. Things should
remain relatively quiet through Sun morning. Then, deepening low
pressure system over the OH valley will bring another round of
widespread showers and thunderstorms late Sun through Sun night.
Some storms may become severe given strengthening wind fields
and unstable conditions. Isolated tornadoes are also possible
assuming sufficient instability develops ahead of main
convective line along frontal zone. While the t-storm activity
will likely persist through much of the night, the most intense
should occur between 21Z Sun-03Z Mon. Showers will end quickly
by daybreak Mon with frontal passage.

[yoda]

STW up in W MD and extreme N WV... winds to 60mph

[CAPE]

Heavy rain threat is pretty decent tonight along I-95. WPC has a marginal risk for excessive.

From Mount Holly AFD for this evening into the overnight:

We have concerns for heavy rainfall with this second round of showers and embedded storms. PWATs should rise to 1.5 inches in the warm sector as moisture is drawn northward with a few hundred j/kg of elevated CAPE being shown by models. Also, the south/east progression of the front should slow down with the mean flow running nearly parallel to it. So for these reasons not only will heavy rainfall be a concern but also the potential for training of heavier shower/storms in a SW to NE orientation. So this all said, urban and and small stream type flooding looks to still be a threat overnight as localized rainfall amounts of 1-2 inches will be possible within just a few hours.

[yoda]

Tree damage reported in Cumberland with the severe thunderstorm in W MD

[CAPE]

High temp forecast busted big time today, but it is juicy out there. Predicted high was 77. Made it to 69. Currently 66/65.

[yoda]

@high risk

What do you think of the 00z NAM NEST tonight?  STP looks to be pretty high across the region from 02z to 08z MON... looking at it on weather.cod.edu

[yoda]

Just NW of CHO... Rockingham/Greene/Albermarle county area... first of the year lol

[high risk]

1 minute ago, yoda said:

@high risk

What do you think of the 00z NAM NEST tonight?  STP looks to be pretty high across the region from 02z to 08z MON... looking at it on weather.cod.edu

         I was looking at it when you posted.    Sunday night could be very, very interesting around here.     As I noted earlier, the NAM keeps temps well up in the 60s Sunday night, so the usual big drop in overnight instability here won't be an issue.    While the overall wind profiles have some veer-back-veer in them (which can limit the ability of cells to stay discrete), and the cape is a bit "tall and skinny",  the low-level shear looks truly outstanding, and the NAM NEST certainly suggests some cells out ahead of the main line.      Tomorrow's day 2 for Sunday/Sunday night will almost certainly extend slight risk into our area, and it could end up as an enhanced risk.

[yoda]

1 minute ago, high risk said:

         I was looking at it when you posted.    Sunday night could be very, very interesting around here.     As I noted earlier, the NAM keeps temps well up in the 60s Sunday night, so the usual big drop in overnight instability here won't be an issue.    While the overall wind profiles have some veer-back-veer in them (which can limit the ability of cells to stay discrete), and the cape is a bit "tall and skinny",  the low-level shear looks truly outstanding, and the NAM NEST certainly suggests some cells out ahead of the main line.      Tomorrow's day 2 for Sunday/Sunday night will almost certainly extend slight risk into our area, and it could end up as an enhanced risk.

Def agree and good post.  I edited my post above and posted a sounding at 03z MON a little bit NW of CHO... prob overdone but PDS TOR lol

[Kmlwx]

2 minutes ago, high risk said:

         I was looking at it when you posted.    Sunday night could be very, very interesting around here.     As I noted earlier, the NAM keeps temps well up in the 60s Sunday night, so the usual big drop in overnight instability here won't be an issue.    While the overall wind profiles have some veer-back-veer in them (which can limit the ability of cells to stay discrete), and the cape is a bit "tall and skinny",  the low-level shear looks truly outstanding, and the NAM NEST certainly suggests some cells out ahead of the main line.      Tomorrow's day 2 for Sunday/Sunday night will almost certainly extend slight risk into our area, and it could end up as an enhanced risk.

Bullish is what I like to hear. 

[yoda]

Charles County MD at 08z MON aka La Plata tornado zone from the 00z NAM NEST 

[yoda]

New Day 2 has SLGT almost to the i95 corridor and west for late Sunday into Sunday night

[yoda]

Falling asleep - yes I know its 4am - and a loud rumble of thunder woke me back up

[Sparky]

Heard some thunder late yesterday evening and overnight.