2018 Mid-Atlantic General Severe Discussion

[Kmlwx]

I just hope we can manage something a little more exciting to track this year than our normal pencil thin squall lines. Ring of fire pattern could be interesting...or anything with a big low going to our west with a little low developing close in. 

[Thanatos_I_Am]

2 minutes ago, Kmlwx said:

I just hope we can manage something a little more exciting to track this year than our normal pencil thin squall lines. Ring of fire pattern could be interesting...or anything with a big low going to our west with a little low developing close in. 

I’m in the severe tracking for some good CG lightning and hail. Wind is meh to me and heavy rain is cool until my garage has standing water in it. 

Will never forget the best storm here in years. July 19, 2016 around 10pm. Hell of a little cell (that popped on a cool front boundary type thing I believe) that produced some of the most prolific lighting I’ve ever seen. Wishing for some more of those this summer. 

[Ellinwood]

1 minute ago, Thanatos_I_Am said:

I’d figure up north you can get some nice elevated spots for seeing shelf clouds etc nicely as they come in. I struggle here in Rockville with no elevated areas; can’t see any lightning until it’s over me. Thanks for the tips.

I’d love to find some great places, preferably facing west, that are elevated and not too far off the beaten path.

Parking garages are your best bet. Tried several locally from Rockville to Gaithersburg... the Target one near Twinbrook/355 isn't that great, but works in a pinch. In Gaithersburg, the one in Old Town off of W Diamond Ave/355 is pretty good. Another new parking garage popped up in the new development in Gaithersburg next to the Harris Teeter which also has a good view. Good areas to go to if you're just looking for a good local view and don't want to keep driving and tracking the storms as they move.

Other than that, the farm areas west off I-270 from Poolesville northward aren't too bad if you're looking to stay more local. And actually, the area southwest of Frederick is a decent spot, too. Forgot that area in my original post.

[Thanatos_I_Am]

3 minutes ago, Ellinwood said:

Parking garages are your best bet. Tried several locally from Rockville to Gaithersburg... the Target one near Twinbrook/355 isn't that great, but works in a pinch. In Gaithersburg, the one in Old Town off of W Diamond Ave/355 is pretty good. Another new parking garage popped up in the new development in Gaithersburg next to the Harris Teeter which also has a good view. Good areas to go to if you're just looking for a good local view and don't want to keep driving and tracking the storms as they move.

Other than that, the farm areas west off I-270 from Poolesville northward aren't too bad if you're looking to stay more local. And actually, the area southwest of Frederick is a decent spot, too. Forgot that area in my original post.

That’s clever. Never thought about parking garages (as long as they are free  ). In just my other times up in Frederick, Urbana and Middletown I’d always imagine how beautiful the storms would look coming in. I remember one time hiking sugarloaf as a storm rolled in. Crazy, crazy view there. Not so easy to get up. 

[Kmlwx]

Never too early

[George BM]

For Wednesday, 4/04/2018.

[Kmlwx]

I'll take it! MARGINAL WEDGES is what I interpret that to mean. 

[Kmlwx]

The timing for Wednesday is quite early in the day. But the 12z NAM does get a brief/narrow nose of okay parameters for this time of year into the area around 15z. 

[Jandurin]

3 minutes ago, Kmlwx said:

I'll take it! MARGINAL WEDGES is what I interpret that to mean. 

fringed again

[high risk]

500-750 j/kg of sfc-based cape seems doable for Wednesday morning, and the shear looks good, with strong wind fields in place through the column.    With the strong forcing, I expect a squall line as opposed to discrete cells, with a decent wind threat.   The NAM3 seems to show this well, as I expect that we'll end up with a slight risk at some point.    The risk can go to enhanced if we end up with greater instability.

[yoda]

29 minutes ago, high risk said:

500-750 j/kg of sfc-based cape seems doable for Wednesday morning, and the shear looks good, with strong wind fields in place through the column.    With the strong forcing, I expect a squall line as opposed to discrete cells, with a decent wind threat.   The NAM3 seems to show this well, as I expect that we'll end up with a slight risk at some point.    The risk can go to enhanced if we end up with greater instability.

I wouldn't be surprised to see a weak spin up given SRH and some curvature in the hodo... nor a few hail reports with 12z NAM showing decent mid-level lapse rates

[Ellinwood]

1 hour ago, yoda said:

I wouldn't be surprised to see a weak spin up given SRH and some curvature in the hodo... nor a few hail reports with 12z NAM showing decent mid-level lapse rates

Not sure where you're seeing curvature on the hodo... I'm seeing pretty unidirectional wind. Only SRH is coming from the speed shear. This should just be a line of heavy rain and embedded storms with gusty winds. Some minimally severe hail in the areas of highest CAPE. The core of the upper-low and surface low are too far removed to the north to give us any sort of decent directional shear in the low-to-mid levels.

[yoda]

6 minutes ago, Ellinwood said:

Not sure where you're seeing curvature on the hodo... I'm seeing pretty unidirectional wind. Only SRH is coming from the speed shear. This should just be a line of heavy rain and embedded storms with gusty winds. Some minimally severe hail in the areas of highest CAPE. The core of the upper-low and surface low are too far removed to the north to give us any sort of decent directional shear in the low-to-mid levels.

[Ellinwood]

Ah. Still not that great for something that's going to be forced along the cold front... at least IMO it doesn't look like there's enough low-level rotation to overcome the more unidirectional forces to drop a tornado, but I could be wrong.

[yoda]

3 minutes ago, Ellinwood said:

Ah. Still not that great for something that's going to be forced along the cold front... at least IMO it doesn't look like there's enough low-level rotation to overcome the more unidirectional forces to drop a tornado, but I could be wrong.

Agree with you... its not great curvature and SRH is okay... just wouldn't be surprised if there was a weak spin-up somewhere

[csnavywx]

It's V-B-V, making that prospect even tougher than normal. It's definitely favored for a narrow forced line. On the upside, there's a bit of a remnant EML in there, especially further south, so with low WBZs and decent mid-level CAPE, small hail might be common.

[George BM]

3 minutes ago, csnavywx said:

It's V-B-V, making that prospect even tougher than normal. It's definitely favored for a narrow forced line. On the upside, there's a bit of a remnant EML in there, especially further south, so with low WBZs and decent mid-level CAPE, small hail might be common.

Excuse my ignorance but what is "V-B-V"?

[csnavywx]

Veer-Back-Veer profile

[yoda]

00z NAM 3K has decent squall line or low topped line come through the region 15z to 16z on Wed

[George BM]

Day 2 outlook..... Fringed. 

[high risk]

Newest NAM3 still wants to develop a forced line of convection right on top of the DC Metro area during the late morning, with it looking decent for the east side of the area and into northeast MD and the eastern shore.    The HRRR brings the overnight convection further east and kills it late which seems to inhibit better development in our area during the morning. The HRRR would be a big whiff;  the NAM3 isn't great, but areas to the east could certainly see some stronger wind gusts.

[yoda]

Maybe a slight chance late Sunday?  Battleground with the back door front?  LWX morning AFD:

Sunday into Monday, the cold front approaching from the west will
come into play. There seems to be the possibility that the region
could be affected by a cold front moving in from the west and a
possible back door front shifting in from the north. A high pressure
system over eastern Canada will likely determine how far south the
back door front moves into the region and how temperatures are
affected on Sunday. The Euro has the cold front approaching from the
west and moving through the region early Monday morning between 6Z
and 12Z. Euro also tries to bring the back door front southward from
New England. The GFS and Canadian both keep the back door front
further north in PA and New England. If the backdoor front remains
north of our CWA, then temperatures could soar once again into the
70s. If the the backdoor front makes its way into our region,
temperatures will likely be in the mid to upper 40s or lower 50s.
Temperatures for Sunday will depend on the position and strength of
the high in Canada. Precipitation is possible Sunday and the
position and timing of both fronts will determine when
precipitation will move into our region. The main body of rain
looks to affect our region late Sunday into early Monday. The
setup of both fronts could lead to a threat for thunderstorms
and strong winds Sunday and Monday. Chances of precipitation
will be possible Sunday through Monday evening. There is still a
lot of variability between models when it comes to the
interaction of the two cold fronts and the strength of the high
over Canada.

[Kmlwx]

Wooo - our first shot at our first meh of the season!

[yoda]

I think 12z GFS looks decent for the area from 00z SUN to 12z MON... even though its overnight threat for storms... also looks like a good chance for heavy rainfall

[yoda]

Afternoon AFD from LWX regarding Sunday into Monday morning:

The forecast becomes more interesting by Sunday as an area of low
pressure approaches the region from the west. Southerly flow will
continue to advect moisture into the region and reinforce the warm
airmass that will already be in place. Surface dewpoints will climb
into the low to mid 60s, making it feel a touch humid. With the
higher levels of moisture in place, skies will be mostly cloudy on
Sunday. In response to a 1040 hPa high situated over James Bay,
models push a backdoor cold front through New England and into
northern portions of the Mid-Atlantic. The vast majority of model
solutions keep this front north of our forecast area, but it will
need to be watched. The current thinking is that we will remain in
the warm sector and temperatures will once again be well above
average, with temps reaching the 70s (but a few degrees cooler than
previous days with more cloud cover around). Temperatures could be
appreciably colder than currently forecast if the backdoor front
makes it into the area. Model guidance has trended slightly slower
with the progression of the system as a whole, which means that
conditions should stay mostly dry during the morning hours.

The best chance for precipitation will likely come late Sunday
afternoon through Monday morning. As the upper level trough
approaches from the west it will take on a negative tilt. Strong
forcing for ascent will overspread the area Sunday night. We will be
located under strong DCVA out ahead of the negatively tilted upper
level trough, and will also be positioned in the right entrance
region of a 130+ knot jet streak. Days of strong southerly flow out
ahead of the trough will have transported an anomalously moist
airmass into the region, with PW reaching near 1.5 inches (2-3 sigma
above normal). Strong forcing for ascent, coupled with near record
daily PW values will make heavy rainfall likely Sunday night. It
appears as though there will be some surface based buoyancy present
Sunday afternoon through Monday morning. At the same time strong
winds will be present just off the surface, so gusty winds and
thunder would be a possibility if an organized QLCS were to form
along the leading edge of the strong upper level forcing.

[Eskimo Joe]

Anything less than 4" across a good swath of the region isn't heavy rain.  1" - 2" over 12 hours, especially with us being dry and starting to leaf out, is the height of meh.

[Jebman]

You are gonna get your rain, and you are gonna get your leaf out.

We are going to see plenty of severe weather this spring, and there will be more serious windstorms. When we get serious windstorms with leaves on the trees - damage will be catastrophic region-wide.

I hope we never ever get a strong hurricane up the Chesapeake Bay. That would amount to long duration very damaging winds - WITH FULLY LEAVED TREES - that would make the March 1-2 windstorm look like a gentle summer breeze. There would be so damned much house damage, that entire neighborhoods would have to be written off.

[Jandurin]

14 hours ago, Eskimo Joe said:

Anything less than 4" across a good swath of the region isn't heavy rain.  1" - 2" over 12 hours, especially with us being dry and starting to leaf out, is the height of meh.

widespread 2" of rain would be meh for severe maybe but really really good for spring

[yoda]

Brief severe threat Monday morning into early afternoon?  12z NAM sounding at 15z MON looks good enough for damaging winds and or a chance of an isolated tornado at KIAD and toward 18z at EZF/KDCA 

[Kmlwx]

Looks pretty meh.