July 26, 2012 Severe Weather Potential

[MJO812]

In Staten Island at 7:30pm

[earthlight]

Big event for much of the Northeast US from PA to NY and into NJ/CT...even stretching back into the TN Valley

[Isotherm]

Certainly not a bust on the larger scale view, but I think most of us were expecting something better than run of the mill strong storms given the impressive parameters overall. At least we're getting some decent rains tonight.

[Dsnowx53]

The winds were definitely underwhelming, but I loved the structure...some of the best structure I've seen. That alone made this stand out for me.

[Cyg]

Heres some video I took of the storm. The timelapse in the beginning is probably the best part as the storm itself was just OK.

[media]

[/media]

[earthlight]

One day once I retire, I'll find out what the heck causes so many severe storms to just collapse as they approach my area

You have to remember that although the storms are sitting in 3000 joules of cape, the storms were moving very fast and ingesting parcels from areas to the east that were not as wildly unstable with some CIN evident on mesoscale analysis. Dsnow also has a good point about the storms racing eastward "ahead" of themselves..for the lack of a better term to describe it .

In addition there was certainly a few issues with the 500mb pattern which myself and a few others talked about yesterday...the gradient was nicely placed for the track of the MCS but there was a lack of a strong shortwave and the 500mb heights even rose a bit late this afternoon...which is never a good sign.

In the end, hindsight is 20/20 and we'll learn from it which is what forecasting is all about...especially severe weather, and especially severe weather in the Northeast US which is very fickle. Having a high-end event verify here (especially for such a large number of people on this board who were expecting a huge event) needs a tremendous amount of pieces of the puzzle to fall into place perfectly...more often than not they don't which is what makes the high end events (5/31/98, early 2000's MCS's, etc etc) so special.

[Hailstorm]

Perhaps the storms outran the best instability and ran into a bit of capping? Possible considering how fast the storms were moving and that everything discrete was so close to the line itself as opposed to way out in front.

Right around 6 PM, the NYC area had the best instability values in many years from what I recall. We easily had an impressive 3500 j/kg of MLCAPE with 2500 of SBCAPE. LI was around -7*C and low-level lapse rates were at 6 g/cm, so those were sufficient enough because of the aid of good theta-e advection and convergence. Shear was great at 45+ knots and we even had good supercell and derecho indices along with impressive Craven values.

However, we lacked EHI /helicity as it was only 150 m2/c2 at 3 km. South PA had much better Sigtor values than us. CIN and a lack of EML was a factor as well as already mentioned.

Things really went downhill for us after 6 PM through 7:30 when the anvil blowoff from the PA bowing segments hurt our SBCAPE, LI and lapse rates.

[Dsnowx53]

Right around 6 PM, the NYC area had the best instability values in many years from what I recall. We easily had an impressive 3500 j/kg of MLCAPE with 2500 of SBCAPE. LI was around -7*C and low-level lapse rates were at 6 g/cm, so those were sufficient enough because of the aid of good theta-e advection and convergence. Shear was great at 45+ knots and we even had good supercell and derecho indices along with impressive Craven values.

However, we lacked EHI /helicity as it was only 150 m2/c2 at 3 km. South PA had much better Sigtor values than us. CIN and a lack of EML was a factor as well as already mentioned.

Things really went downhill for us after 6 PM through 7:30 when the anvil blowoff from the PA bowing segments hurt our SBCAPE, LI and lapse rates.

The environment out ahead of the storm was probably lackluster, though. The storm takes inflow from the environment out ahead of it as well. It's not all about what environment the storm is currently in.

In west and central PA, extreme instability was constantly ahead of the line.

[Dsnowx53]

Kinda weird though that based on the reports, you'd think that all of the northern half of NJ got destroyed...but for the most part it seems like the winds were underwhelming.

[Dsnowx53]

You have to remember that although the storms are sitting in 3000 joules of cape, the storms were moving very fast and ingesting parcels from areas to the east that were not as wildly unstable with some CIN evident on mesoscale analysis. Dsnow also has a good point about the storms racing eastward "ahead" of themselves..for the lack of a better term to describe it .

In addition there was certainly a few issues with the 500mb pattern which myself and a few others talked about yesterday...the gradient was nicely placed for the track of the MCS but there was a lack of a strong shortwave and the 500mb heights even rose a bit late this afternoon...which is never a good sign.

In the end, hindsight is 20/20 and we'll learn from it which is what forecasting is all about...especially severe weather, and especially severe weather in the Northeast US which is very fickle. Having a high-end event verify here (especially for such a large number of people on this board who were expecting a huge event) needs a tremendous amount of pieces of the puzzle to fall into place perfectly...more often than not they don't which is what makes the high end events (5/31/98, early 2000's MCS's, etc etc) so special.

Yeah, the shortwave was pretty far west, which pumped up the heights out ahead of it a tad. Without the height falls, it's hard to get good ML Lapse rates.

If the storms were delayed a bit more, they could have perhaps occurred when the heights were falling a bit. But these blew through so fast that the height falls never caught up, and the storms ran into the height rises.

[NickD2011]

A derecho happens in this area once in four years, and we already had a derecho last month. It didn't hit us, but it was there. Everything needs to come together perfectly for a long distance to get a derecho, and the conditions in the entire path of the derecho have to be supportive, or else the derecho will die out. The mountains to our west usually weaken severe storms, and the marine layer further weakens them.

[ict1523]

It got ridiculously dark, but that was pretty much the only impressive aspect of this storm. I was at work in Bayside, and I also don't think the winds surpassed 30mph. No wind damage around anywhere either. Some decent lightning, almost no thunder though. Heavy rain, but nothing amazing.

Last week's storms were better, and ever since 9/16/10 my expectations for storms have increased.

[Snowlover76]

A derecho happens in this area once in four years, and we already had a derecho last month. It didn't hit us, but it was there. Everything needs to come together perfectly for a long distance to get a derecho, and the conditions in the entire path of the derecho have to be supportive, or else the derecho will die out. The mountains to our west usually weaken severe storms, and the marine layer further weakens them.

Labor Day 1998 is a perfect example of all the ingredients coming together to allow a derecho to hit our area head on.

[Sundog]

It got ridiculously dark, but that was pretty much the only impressive aspect of this storm. I was at work in Bayside, and I also don't think the winds surpassed 30mph. No wind damage around anywhere either. Some decent lightning, almost no thunder though. Heavy rain, but nothing amazing.

Last week's storms were better, and ever since 9/16/10 my expectations for storms have increased.

To give you an idea of how light the winds were, I'll tell you about this fairly large branch near me house. It's broken and is hanging from a tree, barely holding on by wrapping its thinner tip like a hook around another healthy branch. That tip is maybe a quarter inch thick. That branch is still hanging.

[Minnesota Meso]

I have dropped in several times today, at least you all had something to track and to stretch your forecasting minds, glad some of you are getting the rain. Up here in fly over land our biggest challenge has been forecasting a breakable or unbreakable cap. While in most years we may have seen 2-5 severe outbreaks over the southern 2/3 of MN we have only seen one this year, and that was after sunset, and that wasn't that wide spread. Good Luck forecasting, and it will be interesting to see if any WFO's put out a post script summarizing the event and why it fell apart as it approached the coast. I think what happened today is kind of reminiscent of what often times happens along the North Shore of Lake Superior. As storms approach that area they often times are effected by the ENE sea breezes that occur and they of course weaken dramatically.

[CooL]

Maybe the storms just did what they do 98% of the time in my experience tracking severe weather. And that is gradually weaken as they pass the DE river..roughly.. This happens year round and did not suprise me today at all. Whether its topography, marine layer, or incredibly bad luck, its just the way it is around here.

Bring on winter

[Ian]

DCA outgusted EWR with an outflow boundary.

[earthlight]

DCA outgusted EWR with an outflow boundary.

[Ian]

though i'd still wager it sucked more here since it didnt rain.. but expectations were lower i suppose

[Dsnowx53]

DCA outgusted EWR with an outflow boundary.

[Stormlover74]

Cool lightning show on the 20th floor of revel..but somehow all the storms are moving NE now

[LocoAko]

Just a few quick shots of the structure we observed in Mount Olive, NJ (didn't come out as well as I'd hoped).

[andyhb]

This was the setup on 5/31/98, for reference...two days later there was another significant tornado outbreak in the Northeast...

[Dsnowx53]

Most of my photos are what Jake got, but worse quality. I'll just add some anyway.

[Thunderdude]

The storms were still pretty good. Got quite dark and winds gust were at least 40 to probably 45 mph with very heavy rain and of course good lightning show with some loud thunder thrown in there. Didn't beat the Derecho 98 event but still a strong cluster rocked the area though.

[Guest Pamela]

I always laugh at the "nothing ever happens here" from the N. Jersey, NYC and L.I. crowd. Over the last 30 years annual precipitation is up to around 50 inches per year....show me a place north of N. Carolina and east of the Mississippi that is that wet (outside of the mountains). And don't claim the entire precipitation budget can be attributed to bland winter coastal storms producing light to moderate rain...

[SnoSki14]

I always laugh at the "nothing ever happens here" from the N. Jersey, NYC and L.I. crowd. Over the last 30 years annual precipitation is up to around 50 inches per year....show me a place north of N. Carolina and east of the Mississippi that is that wet (outside of the mountains). And don't claim the entire precipitation budget can be attributed to bland winter coastal storms producing light to moderate rain...

Just Imagine if we had a southern California like climate, 70,80s year round with little precipitation and mostly sunny skies.

[NYCSuburbs]

Comparing this to 6/6/10 - both had moderate risks, one somewhat verified while the other was a total bust:

[IsentropicLift]

I think SPC may have seen the writing on the wall. When they did the final convective outlook of the day the mentioned that they had considered upgrading to high risk but after sampling the 18z soundings decided against it. It just goes to show you that you need a lot more than just good shear and instability to get widespread severe. Everyone got all excited because of what was happening near Elmira and points east but we have to remember that even with a moderate risk we were still only in the 45% wind prob, meaning less than half the time would any one location experience severe winds.

The most impressive part of the storm for me was the cloud formations overhead just as the line was arriving. I swear that I could see rotations in the clouds and they were moving very fast. MCS's like these are very common out in the mid-west yet they don't always cause widespread damage. We have just come to expect that they will since they occur so rarely in this part of the country. Learned an awful lot yesterday.

The last thing that I wanted to say was that a few times, beginning as far west as western PA, a few discrete cells popped just east of the line and then quickly fizzled out. This happened more than once. I would like to understand why they were not able to sustain themselves, especially with the particular cell that hit near Bloomsburg around the time that the line was at its peak.

[dbc]

I think SPC may have seen the writing on the wall. When they did the final convective outlook of the day the mentioned that they had considered upgrading to high risk but after sampling the 18z soundings decided against it. It just goes to show you that you need a lot more than just good shear and instability to get widespread severe. Everyone got all excited because of what was happening near Elmira and points east but we have to remember that even with a moderate risk we were still only in the 45% wind prob, meaning less than half the time would any one location experience severe winds.

The most impressive part of the storm for me was the cloud formations overhead just as the line was arriving. I swear that I could see rotations in the clouds and they were moving very fast. MCS's like these are very common out in the mid-west yet they don't always cause widespread damage. We have just come to expect that they will since they occur so rarely in this part of the country. Learned an awful lot yesterday.

The last thing that I wanted to say was that a few times, beginning as far west as western PA, a few discrete cells popped just east of the line and then quickly fizzled out. This happened more than once. I would like to understand why they were not able to sustain themselves, especially with the particular cell that hit near Bloomsburg around the time that the line was at its peak.

100% agree with the bold/underline statements. I also could have sworn I saw some rotation going on just overhead my 30 story Co-op. I'm on the 27th floor and it was impressive. The winds gusted in the 30's probably, maybe 40 and it was a sheet of rain getting blown everywhere. It wasn't the 2010 macroburst but it was pretty impressive. Definitely found it more interesting than what we saw last week.