Threat for thunderstorms Tuesday, March 13th, 2012

[CoastalWx]

Yeah the models actually did a nice job showing the steep lapse rates. Sunday the NAM and GFS had lapse rates in parts of CT near 7-7.5 c/km 500-700mb.

There was enough of a trigger to get things going above the inversion. I'm not sure the backdoor front was deep enough to get lift up to the LFC though.

It was probably one of those things where as the S/W approached, the LLJ probably perked up a bit, and there you go.

[CT Rain]

It was probably one of those things where as the S/W approached, the LLJ probably perked up a bit, and there you go.

Yup, exactly.

[Typhoon Tip]

It was probably one of those things where as the S/W approached, the LLJ probably perked up a bit, and there you go.

Also - there's a kind of unofficially known correlation for severe locally to that which takes place upstream over Michigan, some 24 hours prior... Yesterday, indeed, there were tor warn cells and a watch box for southern and southeaster lower Michigan. Well....there we were ~24 hours later...

There was a small outbreak in Michigan one fabled June, of 1953, and we all know what happened the next day

[CoastalWx]

Also - there's a kind of unofficially known correlation for severe locally to that which takes place upstream over Michigan, some 24 hours prior... Yesterday, indeed, there were tor warn cells and a watch box for southern and southeaster lower Michigan. Well....there we were ~24 hours later...

There was a small outbreak in Michigan one fabled June, of 1953, and we all know what happened the next day

What happened? J/K.

I think you usually want to be more on the se side of the approaching S/W. You'll have the height falls, but if you think of it....this is probably the best way to advect in an airmass with higher lapse rates. It doesn't have to be an EML..just more of a continental type airmass. Usually when the main height fall center approaches from the west or southwest...the lapse rates are putrid and of more subtropical in origin. Agreed about Michigan. Usually a harbinger of things to come.

[Typhoon Tip]

http://www.firstwrit...mpetition.shtml

Huh, ...i doon't get it.

[Wonkis]

tornadic signature from last night

Cool pic!

Hard to judge from one frame of a radar grab, but it only looks superficially like a hook - it's missing the classic 'C' shape.

[ChrisM]

Huh, ...i doon't get it.

"Then it happened: BANG! I was standing under my awning to my front door when a nickel-sized diameter white ball smashed down and bounced off it. It caught the corner of my eye and when I went on the lawn and picked it up, it was solid. You could hear distance roar coming from the west. Oh boy! Then there was another …and another. Big hail, some up to a quarter in size started bouncing off everything in this loud cocophany"

It sounded like a 9th grade english project lol

[40/70 Benchmark]

See..it can happen. It's not the forcefield that you claim it is.

Well, sure....and once in awhile Atlanta, GA sees a snowstorm.

[CoastalWx]

Well, sure....and once in awhile Atlanta, GA sees a snowstorm.

Yeah but you are only impressed with something severe. Even if you get a good tstm with CG...you call it "obnoxiously loud thunder" like you did on June 1st.

[40/70 Benchmark]

Yeah but you are only impressed with something severe. Even if you get a good tstm with CG...you call it "obnoxiously loud thunder" like you did on June 1st.

Exactly.

Last night was very impressive, but I was terrified that it was going to damage my car.....I was ambivalent in the sense that I was torn between terror and excitement.

[CoastalWx]

Exactly.

Last night was very impressive, but I was terrified that it was going to damage my car.....I was ambivalent in the sense that I was torn between terror and excitement.

Terror FTW. It's cool to have hail damage on your car. Battle scars..lol.

[Ginx snewx]

If you can get a hold of water vapor satellite imagery for that timeframe (from around 00Z to 07Z 3/14), you will see that this set up right between two jets, so jet interaction definitely played a part.  Also, the backdoor front was trying to nose down into S NH, and I think that played a part, too, with subtle low level convergence. --Turtle

[Clinch Leatherwood]

Has anyone heard from Will or did he get sucked up in the updraft of this mailbox sized storm?

[40/70 Benchmark]

Well, that was fun....only 9 more months 'til the next round of interesting weather.

[CoastalWx]

Well, that was fun....only 9 more months 'til the next round of interesting weather.

Maybe this is the summer of Ray. Golf ball size hail en route.

[Baroclinic Zone]

Well, that was fun....only 9 more months 'til the next round of interesting weather.

Nice pic.

[MarkO]

I know the CAPE indices were low, but thought I remembered someone (Tip?) posting somewhere they may be higher than NWS forecast. I was certainly surprised to see hail this time of year although in following that cell I somewhat expected it considering the season and temps.

[CoastalWx]

I know the CAPE indices were low, but thought I remembered someone (Tip?) posting somewhere they may be higher than NWS forecast. I was certainly surprised to see hail last night although in following that cell I somewhat expected it considering the season and temps.

There was a lot of CAPE in the mid levels. Elevated instability as we call it. The lapse rates in the mid levels were fairly steep so once any updraft forms..it has the ability to go to town.

[40/70 Benchmark]

Maybe this is the summer of Ray. Golf ball size hail en route.

LOL I'll take the under. My hope is that the tropics will provide some fun for the US.

Nice pic.

Thanks...I emailed it into Elanor.

[MarkO]

I still "see" weather in two dimensions, but slowly learning. I apologize for sounding like a fool.

[CoastalWx]

I still "see" weather in two dimensions, but slowly learning. I apologize for sounding like a fool.

That was a legit question. Nothing wrong with that at all.

[CoastalWx]

LOL I'll take the under. My hope is that the tropics will provide some fun for the US.

Thanks...I emailed it into Elanor.

I noticed a few of those hail stones were angling to the right.

[40/70 Benchmark]

Yeah, no question… The evening was pretty fantastic up at my place in Ayer.

First, about an hour before the hail event there was a spurious, small little thunderstorm cell that popped up and scooted by about 2 miles N of my house. This thing was so tiny that it would fit inside of about 5 or 6 pixels on the radar image. Yet, boy was that sucker beaming lightning bolts. I had about 5 loud CG explosions over about a 3 minute time period as the cell made its closest pass. It was fascinating to see that, because at sunset I was up on the ridge line of the Harvard overlook – there was this hazy pal to the air over the valley. It was as though it were a humid sunset in June! There were a few sparse, shallower cumulus towers around, but they weren't really demonstrating a lot of vertical growth. But an hour after sun set things got interesting.

Then T-Bone calls to tell me he’s got marble-sized hail covering the ground. I was just going to take a look myself as renewed thunder began shaking the windows. I stood out there peering at the sky to the west. The air was dead calm, enough so that you could hear the thunder echoing passed. You could see the sky literally differentiating heavier toward that butterscotch hue (glow of city lights reflecting), right before you. You got the sense that something unusual was immediately pending. Then it happened: BANG! I was standing under my awning to my front door when a nickel-sized diameter white ball smashed down and bounced off it. It caught the corner of my eye and when I went on the lawn and picked it up, it was solid. You could hear distance roar coming from the west. Oh boy! Then there was another …and another. Big hail, some up to a quarter in size started bouncing off everything in this loud cocophany. So loud that it drowned out the thunder. It, too, covered the ground, then changed to heavier rain. It rained uber hard for about 4 or 5 minutes, then it was over.

Later on in my sleep I was kicking myself for not thinking to grab a few of the larger pieces and stick them in the freezer.

March. Unbelievable.

:weenie:

[40/70 Benchmark]

I noticed a few of those hail stones were angling to the right.

Huh

[weatherwiz]

There was some decent helicity values as well which really helped to enhance the updrafts to produce the hail...you also had the dry mid-levels which helped as well.

[CoastalWx]

Huh

Nevermind. Failed weenie joke.

[adamrivers]

Yeah, no question… The evening was pretty fantastic up at my place in Ayer.

First, about an hour before the hail event there was a spurious, small little thunderstorm cell that popped up and scooted by about 2 miles N of my house. This thing was so tiny that it would fit inside of about 5 or 6 pixels on the radar image. Yet, boy was that sucker beaming lightning bolts. I had about 5 loud CG explosions over about a 3 minute time period as the cell made its closest pass. It was fascinating to see that, because at sunset I was up on the ridge line of the Harvard overlook – there was this hazy pal to the air over the valley. It was as though it were a humid sunset in June! There were a few sparse, shallower cumulus towers around, but they weren't really demonstrating a lot of vertical growth. But an hour after sun set things got interesting.

Then T-Bone calls to tell me he’s got marble-sized hail covering the ground. I was just going to take a look myself as renewed thunder began shaking the windows. I stood out there peering at the sky to the west. The air was dead calm, enough so that you could hear the thunder echoing passed. You could see the sky literally differentiating heavier toward that butterscotch hue (glow of city lights reflecting), right before you. You got the sense that something unusual was immediately pending. Then it happened: BANG! I was standing under my awning to my front door when a nickel-sized diameter white ball smashed down and bounced off it. It caught the corner of my eye and when I went on the lawn and picked it up, it was solid. You could hear distance roar coming from the west. Oh boy! Then there was another …and another. Big hail, some up to a quarter in size started bouncing off everything in this loud cocophany. So loud that it drowned out the thunder. It, too, covered the ground, then changed to heavier rain. It rained uber hard for about 4 or 5 minutes, then it was over.

Later on in my sleep I was kicking myself for not thinking to grab a few of the larger pieces and stick them in the freezer.

March. Unbelievable.

You should write books. Drama weather books.

[40/70 Benchmark]

Nevermind. Failed weenie joke.

[Turtle]

Did you see my post? I was/live in Ayer; that cell come directly over head there. Had hail similarly to Littleton - 1.00 at my house (~Quarter size), and it wasn't just a piece or two in a marble storm. There were a lot of them, bouncing pretty loudly off everything for a good 3 minutes.

Hi John.

Yes, I read it after getting home this morning. Will make a note of this when I go in tonight for our Storm Data reports to NCDC. Please PM the approximate time to me. Thanks! What storms, eh?

--Turtle

[weatherwiz]

When I was walking home from work tonight I was thinking about something.

The clues were actually there that told us that if anyone would see anything it would be eastern sections and not western sections.

When looking at the timing a few days out we all discounted eastern areas b/c the models showed the front and s/w trough coming through during the overnight hours and obviously this time of year (and even during the summer) this means loss of daytime heating which leads to less in the way of surface-based instability.

These are the keys that were either missed or overlooked:

1) Dynamics: As the s/w trough continued to approach the region the winds aloft began to strengthen and all the models showed this. The models increased all three of the main jets (low-level, mid-level, and upper-level) and the models even hinted at any developing line would occur just out ahead of the jet streaks...meaning the action could potentially be enhanced thanks to extra lift from the nose of the jets. As the mid-level jet increased (to about 40-50 knots) so did the vertical shear values.

2) Cooling mid-levels: Any time of the year when you have cold-air advection in the mid-levels of the atmosphere you are going to net some instability, both at the surface and aloft (elevated instability). Well yesterday was a classic case of this. Despite it being mid-March as the sun went down we actually didn't see a great deal of cooling taking place at the surface as increasing cloud cover halted radiation and winds from the SW actually warmed some locations up a few degrees once the winds switched there. So while sfc temps remained rather steady we were actually seeing cooling taking place in the mid-levels, this steepened the mid-level lapse rates and resulted in an instability spike. This also helped to erode a very weak cap that was in place.

3) Increased sfc convergence...with the sfc wind direction switching to a more SW direction this increased the convergence just out ahead of the approaching s/w trough/cold front. This slight increase in convergence really helped to lift the surface parcels and parcels in the PBL upward.

Anyways what I'm trying to get at is if you look at past events which produced similar results to this part of MA you'll actually notice the conditions and factors present over that area were extremely similar to conditions/factors present for those past events.

When dealing with eastern MA and getting severe (whether it be hail or wind) you want to see strong CAA in the mid-levels along with increasing dynamics aloft to help aid in lifting. I guess this is true for everywhere but for eastern MA it's incredibly difficult to get severe without any of these factors present.