Jump to content
  • Member Statistics

    17,502
    Total Members
    7,904
    Most Online
    Weathernoob335
    Newest Member
    Weathernoob335
    Joined

2020 Mid-Atlantic Severe Weather - General Thread


Kmlwx
 Share

Recommended Posts

On 4/23/2020 at 8:53 AM, George BM said:

While just about all ensembles have this trough staying over the eastern US for the remainder of the month into the beginning May I wonder if we can get into some W/NW flow action sometime early in May (2nd week?) as the trough slowly lifts and/or shifts eastward (as shown in a number of long range ens. ATM). Just speculation at this point of course... and me thinking out loud. 

You asked:

 

Link to comment
Share on other sites

10 hours ago, poolz1 said:

Any potential for wed night/thurs?  Looks like the 3k has a nasty line coming through WV around midnight....some training looks possible with the slow eastward push.

More likely we get flooding.  If you read the morning AFD from LWX it sounds like we're getting a flood watch later today.

  • Like 1
Link to comment
Share on other sites

13 hours ago, poolz1 said:

Any potential for wed night/thurs?  Looks like the 3k has a nasty line coming through WV around midnight....some training looks possible with the slow eastward push.

       Yeah, wind profiles look awesome to our west Wednesday night, but instability is negligible.     On Thursday, the wind profiles along the I-95 corridor will be decent, but instability again looks to be effectively nada.     Agree with EJ that any threat would be flooding.     It had been looking like the axis of heavy rain Thursday afternoon would set up just to our east, but the 12z NAM is slower, and a heavy rain threat may set up for DC and points east.

Link to comment
Share on other sites

2 hours ago, high risk said:

       Yeah, wind profiles look awesome to our west Wednesday night, but instability is negligible.     On Thursday, the wind profiles along the I-95 corridor will be decent, but instability again looks to be effectively nada.     Agree with EJ that any threat would be flooding.     It had been looking like the axis of heavy rain Thursday afternoon would set up just to our east, but the 12z NAM is slower, and a heavy rain threat may set up for DC and points east.

06z euro with a slightly slower progression as well....Pretty consistent the last few runs for a 2-3" region-wide rain maker.  

Novice question....do you, or anyone, have any resources you can point me towards to help me understand how to assess the risk of severe from a sounding and other parameters?  I do understand the basics but the more I become interested in severe and heavy rains the more complex it seems compared to winter weather.  Never thought I would become interested in severe...but, it seems to have grown on me.

Link to comment
Share on other sites

3K NAM has been overdoing it lately, but looking at latest run, looks like it comes in pretty early tomorrow and is out of here in the afternoon. It moves through slowly, but not slow enough for training, and the line is pretty narrow, so its only about 4 hours of heavy rain in any one location.

Link to comment
Share on other sites

12 minutes ago, osfan24 said:

3K NAM has been overdoing it lately, but looking at latest run, looks like it comes in pretty early tomorrow and is out of here in the afternoon. It moves through slowly, but not slow enough for training, and the line is pretty narrow, so its only about 4 hours of heavy rain in any one location.

Yeah looks pretty meh to me. 

  • Weenie 1
Link to comment
Share on other sites

From the latest LWX discussion:

(snip)
.SHORT TERM /THIS EVENING THROUGH FRIDAY NIGHT/...
Notable trends seen this cycle among global models were that
the GFS trended deeper/more amplified, closer to the Euro with
the upper level trof/closed low fcst to dig across the mid-Atlc
states Thu-Fri. Timing differences with respect to upper level
trof axis moving across the area have decreased significantly
and the rainfall potential has increased somewhat since 24 hrs
ago. Anticipating a widespread moderate to heavy rainfall event
late Wed night into early Thu evening with widespread 1.5 -2.5
inches with the potential for up to 4 inches (reasonable worst
case scenario) with heaviest amounts east of the Blue Ridge and
Catoctin mountains.
Forcing and moisture will be plentiful with
instability lacking which would limit rainfall rates, but
prolonged period of the event, deep moisture, and strong upper
level divergence will compensate for lack of instability. While
heaviest amounts are expected east of the Blue Ridge, enough
spread is shown in the ensembles and difference percentiles to
include areas west of the Blue Ridge. Have issued a Flood Watch
for much of the area separated with two segments, a western
segment with beginning and ending time of 08Z-16Z Thu, and an
eastern segment running from 16Z Thu-02Z Fri.
(snip)

Link to comment
Share on other sites

If LWX is to be believed, I'd expect quite a few road closures due to small streams out of their banks. I DO hope Arlington has fixed its drains and alerted persons living/working in the usual suspect spots (think Westover, the area of South Glebe Road near the sewage plant, etc.).

Link to comment
Share on other sites

While it looks like we'll hopefully avoid some of the nastier scenarios being depicted by various guidance in recent days, I don't think it's worthy of a 'meh' either.     We'll still have a 60+ knot low level jet, some very strong lift from multiple sources including upper difluence, and impressive PW values, and even hi-res guidance can often underdo precip in these events.    And while it looks to be fairly progressive, there are still some hints of a "round 2" Thursday afternoon in the HRRR and ARW2.     Certainly the best chances for big amounts are east of DC, but the chances of really huge totals seem lower now, they're not zero, and we'll still have to deal with issues associated with a heavy event in a short period of time at a minimum.

Link to comment
Share on other sites

For the past several days I've been low-key watching the Sunday system for any severe potential and as of right now late Sunday has slight potential to get interesting should we have enough CAPE (which currently looks modest to perhaps locally moderate with LI of -3 to -5). Deep layer flow looks fairly strong (on the order of 50+ kts in the mid-levels). Should we be able to get enough sunshine for more moderate CAPE it could get interesting for some. Timing does look to be leaning a bit on the later side ATM.

Then there is also still the question of how far north this 'threat' will extend.

#Notanexpertopinion

#Justmy2cents

  • Thanks 1
Link to comment
Share on other sites

20 minutes ago, George BM said:

For the past several days I've been low-key watching the Sunday system for any severe potential and as of right now late Sunday has slight potential to get interesting should we have enough CAPE (which currently looks modest to perhaps locally moderate with LI of -3 to -5). Deep layer flow looks fairly strong (on the order of 50+ kts in the mid-levels). Should we be able to get enough sunshine for more moderate CAPE it could get interesting for some. Timing does look to be leaning a bit on the later side ATM.

Then there is also still the question of how far north this 'threat' will extend.

#Notanexpertopinion

#Justmy2cents

    Indeed!   check out the 12z NAM nest for Sunday afternoon.

Link to comment
Share on other sites

2 minutes ago, Eskimo Joe said:

Sunday screams big hailers and structure for I-66 south.

I think it will depend on where the front (warm front?) sets up shop... could maybe be an isolated tornado if it rides the west to east front?

And big hailers are what to you?  The usual quarter to half dollar size around here or bigger?

Link to comment
Share on other sites

2 minutes ago, yoda said:

I think it will depend on where the front (warm front?) sets up shop... could maybe be an isolated tornado if it rides the west to east front?

And big hailers are what to you?  The usual quarter to half dollar size around here or bigger?

Couple of 1.5" stones based on the setup.  

Link to comment
Share on other sites

Just now, yoda said:

Ah, ping pong ball hail to maybe golf ball then... guess our ML Lapse rates are good enough?

Yea, good LIs are a sign of the capability to really sustain updrafts and we've seen some pretty cold temps upstairs of late so I could see a couple of big hailers ripple off the I-81 corridor and trek into NOVA.  Maryland is probably out of this one unless something big shifts in our favor.

Link to comment
Share on other sites

00z 12km NAM looks decent... has what looks to be a complex of storms (MCS?) Roll through the DC metro region around 03z MON

00z 3km NAM NEST looks intriguing from 00z to 04z MON... looks like a sup comes rumbling down i66 corridor from 02z to 04z

Link to comment
Share on other sites

The SPC outlook discussion is spot on.    Forcing is strong, but the soundings look very meh.    Best chance of severe will definitely be further south (as suggested by EJ), where temps will be warmer, giving some hope of modest cape, but it's pretty iffy there too.    For those north of DC like me, I'll be happy with thunder:  NAM nest looks great for that, but it's a bit of an outlier, with several other CAMS not showing good reflectivity signals north of 66 (VA) and 50 (MD).

Link to comment
Share on other sites

6 hours ago, high risk said:

The SPC outlook discussion is spot on.    Forcing is strong, but the soundings look very meh.    Best chance of severe will definitely be further south (as suggested by EJ), where temps will be warmer, giving some hope of modest cape, but it's pretty iffy there too.    For those north of DC like me, I'll be happy with thunder:  NAM nest looks great for that, but it's a bit of an outlier, with several other CAMS not showing good reflectivity signals north of 66 (VA) and 50 (MD).

18z NAM soundings at KIAD for 00z MON and 03z MON looked pretty good to me... decent SBCAPE and shear... would suggest that the WF or west to east front is somewhere in C MD

Sim radar didnt look too bad on either of the 18z NAMs or RGEM... 18z long range HRRR did suggest though that the front is in N VA as it has best storms just south of me toward EZF

Link to comment
Share on other sites

00z NAM and 3km NAM sim radar look interesting around 03z/04z MON... I guess some sort of an MCS?

Both 00z WRF-ARW and 00z WRF-ARW2 keep majority of storms down by EZF

00z WRF-NMM looks more like the NAM twins but is an hour or 2 faster

00z HRDRPS looks fun DC south

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...