osfan24

1 minute ago, MN Transplant said:

With nocturnal elevated convection, there is a stable layer at the surface with an unstable layer above.  What can happen in these situations is that the thunder can be "ducted" and can be heard at longer distances.

Ahh, thanks. Always looking to learn more. Definitely seemed like that was the case last night.

10 minutes ago, Eskimo Joe said:

Classic sign of nocturnal elevated convection.

Can you explain what that is?

44 minutes ago, North Balti Zen said:

Co-sign on the two rounds of storms for Baltimore - first cluster at 11 pm and then a hellacious storm around 2:30 am. That one must have been a tremendous lightning show. 

Yep, think I woke up around 11 or 11:30 for round one and never really got to bed before the real show started around 2 or so. Had a lot of loud, rolling thunder even when lightning was pretty far away, and several very close strikes. And obviously lots of heavy rain. Not sure how much we got, but had to be at least a couple inches, plus additional rain around 5 this morning. I think the two biggest lightning and thunder storms for this summer for me have come within the past couple of weeks.

2 minutes ago, high risk said:

     The 15z update removed our area from slight risk (still in marginal) and specifically noted the reduced threat for DC/MD/VA in the discussion.

Ok thanks, must have missed that. I knew something didn't seem right.

Where is the excessive rainfall forecast coming from today? Radar looks empty, forecast is not for much today, and while those dumb futurecast things aren't all that accurate, all they show is very isolated storms later.

Had a few close strikes here, especially one that seemed like it was just yards away.

Big storm near Columbia. Thankfully, a lot of it shifted south of Ellicott City but it looks like there may be some re-development, as well as more storms to the west.

Finally put out a Flood Warning there. Looks like that area might be trying to shift a bit to the south but it's been dumping good there for about an hour now.

Ummmm radar not looking so hot for Ellicott City right now. Where is the flood warning there? I'm to the east of that activity and can hear pretty constant thunder. It's gotta be dumping there and it just keeps stalling and re-forming.

Lancaster area ended up the big winner today, though that eastern area of Harford might give it a run for its money. Line is definitely redeveloping west and sagging south, and now there is also an area around the city and south developing and just sitting.

Pretty wild how little rain I've received this week. Some areas to the west have gotten dumped on for sure, but this has been a total bust around here. 

Actually not as high on our chances now. That area around DC hasn't advanced much and seems to pressing east a bit. Probably going to end more over the bay than in the Baltimore area, and all that stuff down by Richmond is going well east. Looks like it's our turn to miss out this week.

If we can keep the sun shining another couple of hours, it looks like we could get a lot of showers and storms to form just ahead of that line. Could be a really wet afternoon and evening.

35 minutes ago, North Balti Zen said:

On top of that, it rained quite a bit last night for a lot of people in our forum, so not sure where cranky was wrong...

Cranky is really good and obviously you have the have's and the have not's when it comes to this type of event and scattered storms, but last week he hyped up a repeat of the previous week and that's not at all what has happened. This has been more of a mountain deal, which he has emphasized more recently.

I don't think people were upset because they were expecting huge snowstorms. I think they were upset because there WERE huge snowstorms and they danced around us. The opportunities were there. The beaches had a legit blizzard. Areas along the Jersey Coast and north of there got a big storm or two. It was so close yet so far, which is where my frustration came from. If everyone was swinging and missing during a crappy pattern, that's not unexpected.

GFS seems to like this event for at least some decent rain but NAM is not all that impressed and HRRR is really nothing unless you are in Central PA.

1 hour ago, smokeybandit said:

HRRR says no rain during the day.  But wants to give us a good bit late tonight.

Yeah HRRR is very impressive this evening and then again overnight into tomorrow morning

Had some decent thunder and lightning but tonight doesn't seem like anything more than a quick line of storms. Not seeing a flooding threat until the weekend.

HRRR and NAM certainly are not very interesting for today or tomorrow. Looks like Saturday or more likely Sunday is when we get pretty much all the rain.

46 minutes ago, losetoa6 said:

Gfs really closes off at 500 over us Saturday and look at 700 mb moisture core ..it's right over us .Interesting like others have said. Someone could get crushed .

. 

What do I have to do to get this in January?

1 hour ago, Eskimo Joe said:

Slowly getting interested in the flooding and conditional severe potential for the Thursday - Saturday timeframe.  SE flow + lift + remnant tropical system = intriguing.

Yeah the NAM and GFS are both hinting at that, especially Saturday, though obviously out of NAMs range.

20 minutes ago, North Balti Zen said:

I don't want to engage, really, but maybe slow one's roll with dismissing too quickly the effect that development in terms of sub-divisions and shopping centers in the hills above Ellicott City has had on what has happened in Ellicot City with the last few floods. There has been enough forest and fields lost to that development that the amount of water that now cascades into those tributaries is markedly different than where it was even 15 years ago. The previous issues that Ellicott City has had with flooding historically were from the Patapsco filling up and backing into the low end of Main Street. What happened in 2016 and over the weekend was very very different - run-off from the higher ground filling and over-whelming the streams running through the town.  That is a development issue, and that has been a point of contention for locals there as the developments have been green-lit.

I'm sure it was somewhat of a factor or exacerbated the situation, but the bottom line is they had a very intense, long-duration event and the topography of the area literally checks all boxes in terms of what you would look for when it comes to a town and flash flooding. It is basically built in a valley surrounded on all sides by steep hills, is a narrow street lined with buildings, sits next to a major river and is also built on top of a river. It's essentially sitting in the bottom of a bucket or bowl. Fill up cups of water and dump them into a bowl from all sides and watch what happens.

The other evidence that this is almost entirely topography driven is that nearby Catonsville received even more rain than Ellicott City. While there was some flooding, it was not the catastrophic damage we saw on Main Street. Catonsville is more developed than Ellicott City, but it doesn't have buildings that sit near the Patapsco, nor is it built on top of a river.

On ‎5‎/‎27‎/‎2018 at 8:01 PM, PrinceFrederickWx said:

I added today's Ellicott City flooding to the July 30, 2016 option.

Good Lord...

Still think it's the derecho because of the region-wide impact, but if you combine the two flash flood events, consider the devastation to Ellicott City twice, the loss of life, and also consider this time impacted areas of Catonsville through the city to the east side, it has to be considered. It was certainly the most impactful with regard to the economy, but again, the number of people impacted is very small. Unless you live in that narrow stripe that was trained over, you hardly got any rain. I know it was just a deluge just several miles northwest of me and I got very little rain and some distant thunder.

Frankly, the image showing development above Main Street Ellicott City is not all that crazy to me. There isn't really that much development there to blame this on that. I'm sure it played a small part in exacerbating things, but anytime you have a narrow mill town at the bottom of a hill with a major river running both under and through it and you get insane rainfall rates for a few hours, this is what happens. Catonsville is more developed than Ellicott City, and while there were flood issues there, nothing destroyed the town because the river doesn't run near the developed areas and the town isn't located at the bottom of a steep hill.

1 minute ago, Eskimo Joe said:

Still need to wait for runoff to stop.

Oh got it. I took it as there was more rain coming. Yeah that's going to take some time.