7/28/06: FCST: Northeastern U.S.

Do I dare say that the Northeastern United States may end up being a better place to watch severe weather this year than the Plains? It's arguable but this year has been extremely active in the Northeast with numerous Severe weather episodes. Last night a thunderstorm erupted over Staten Island, NY and had so many cloud to ground lightning strikes that 30,000 CON ED customers were without power. Wires, trees and power poles were down everywhere b/c of direct lightning strikes.

Today the setup is more favorable dynamically than yesterday for severe weather. Currently a weakening MCS is moving across Central New York. An enhanced area of elevated convection is occurring north of Mohawk Valley in line with the MM5 and WRF model forecasts. While there will likely be some cloudiness and showers in the Eastern NY and Western New England through midday...instability, moisture and 70f dewpoints are in place. Breaks of sun should allow temperatures and enough CAPE to generate by early to mid afternoon to refire thunderstorms. The dynamics are in places with 250mb divergence providing great venting (50-65kts) and even a 400-500mb jetstreak of 50kts indicated by some model soundings. 0-6km shear values are 35-45kts this afternoon as a stronger vort max moves overhead.

So, in a nutshell...while instability will not be AS great as it had been the past couple of days, we sure do have plenty of tropical moisture, dynamics and lift in place to generate strong and severe thunderstorms this afternoon from Eastern New York into New England and south to NJ and Eastern PA. The best organized severe thuderstorms should form into lines of bowing severe storms...and possibly an MCS (as indicated by the WRF and the MM5 Stony Brook model). Wind damage should be the best bet from this event but isolated supercells from the Hudson Valley on East and South are possible with the more southerly component to the wind enhancing low level directional shear.

Lets hope the breaks of sun and re-firing storms materialize and we will be in for a fun day!!!!

PS: It looks like we will have a continued threat for severe thunderstorms Sunday-Monday and into the middle next week as the ring of fire puts the Northeast in a favorable NW flow pattern with a possible backdoor Cold Front adding to the mix.
 
10:20am:
Based on satellite images which shows clearing toward Poughkeepsie, NY and the fact that strong deep moisture convergence is occurring invof BGM combined along with a 25kt 850 wind and 45-50 kt 500mb wind approaching from the west....I may target Poughkeepsie, NY this PM for a chase. It is only 1 1/2 hours away and I can hop on NYS Thruway to get there. It seems like that area will tend to get more sunshine and destabilization than areas 50 miles North will (Albany area).
 
Weather Underground Radar

Jersey City and New York City look like they're going to get pounded. There is a WICKED line of storms just to the west-beyond some strong cells that are moving into Jersey City and New York City. I was going to head out today-but a stomach virus and severe weather messed up those plans. I may have to get offline soon-as I have dial up and I don't want to fry my computers if lightning strikes. :eek:
 
New Haven just got whacked pretty hard. It got pitch black, with very intense winds as the gust front passed over, and continuous thunder and lightning. I actually got a good look at the cloud base right out of my apartment window, and the motion up there was just insane. Wish I could've got a better look, I'm limited here to just a little corner of the sky on account of neighboring tall buildings. The SPC has put out an MD that mentions a threat for isolated supercells over the next few hours in Southern New England... But it looks to me like it's just going to be one big line, with maybe a few embedded supercellular features. Maybe we'll get another chance in a few days, it does seem to be an active year, especially compared to the past couple of years which have really sucked for severe weather here in the Northeast.
 
Actually there were a few supercells that formed ahead of the line in Southeastern NY and Western MA. One supercell moved from Columbia County, NY into Berkshire County, MA and sure looked like it could have had a tornado TVS signature in it. It was Meso's for many scans and damage has been report where those meso's popped up. It was definitely a supercell and could have dropped an isolated tornado from it. The other most significant supercell was across Dutchess County, NY. That was a monster and has confirmed wind damage along its path as well.

The overall pattern was very good for severe weather but i think most of us got burned. It should have been a much bigger and widespread outbreak than it was. The morning showers and cloud cover screwed us. Also...it seems that the surface trof went through the Hudson Valley quite early and squelched the real convergence from reaching its potential. I should have headed south like I originally planned. Oh well. Here's hoping for the next one.
 
Actually there were a few supercells that formed ahead of the line in Southeastern NY and Western MA. One supercell moved from Columbia County, NY into Berkshire County, MA and sure looked like it could have had a tornado TVS signature in it. It was Meso's for many scans and damage has been report where those meso's popped up. It was definitely a supercell and could have dropped an isolated tornado from it. The other most significant supercell was across Dutchess County, NY. That was a monster and has confirmed wind damage along its path as well.

The overall pattern was very good for severe weather but i think most of us got burned. It should have been a much bigger and widespread outbreak than it was. The morning showers and cloud cover screwed us. Also...it seems that the surface trof went through the Hudson Valley quite early and squelched the real convergence from reaching its potential. I should have headed south like I originally planned. Oh well. Here's hoping for the next one.
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By the time I wrote my post things were mostly linear, but yeah, I was watching that supercell in MA, it was probably the storm of the day, definitely the cell to be on if you were chasing. I agree the Dutchess County monster that formed later was pretty formidable looking too. And did you notice the supercells up in Maine? All day long a series of isolated supercells tracked across southern ME, some of them looking very nice indeed on radar, with obvious strong velocity couplets. Relatively early on there was a small supercell sporting a well-defined hook echo - I was a bit surprised not to see a warning on it. Actually I was kinda surprised to see supercells up there at all, since the index numbers were much better down here. But we got mostly blobs, while they were getting supercells. I'm beginning to wonder about the usefulness of the supercell index in these situations. Over the past few weeks there have been many instances when the supercell index was in the double digits, but the storms that formed weren't supercellular. And then on the day we did get a classic supercell, complete with long track tornado, the index was comparatively low. Clearly, good low-level shear trumps CAPE every time in these semi-marginal situations, and you have to keep that in mind when looking at the Sup index.
 
I agree that low level shear certainly trumps the CAPE. All you need is enough instability to generate a thunderstorm and updraft. The shear will do the rest. It is just like the right front quadrant of landfalling tropical systems. Only a little instability is needed to produce tornadoes because the shear is intense. I guess the same could be said for feeder bands also. Regardless, there are no set rules with these indicies...just guidance and paramaters that give you an idea of severe weather mode. And as we know...thunderstorms "live and breathe on their own" doing whatever they want to do. LOL.

The thing that annoyed me yesterday is that it was so humid and tropical outside that numerous showers, t-showers and drizzle developed and killed the real deal outbreak from happening. 95% of the storms out there yesterday were mush!!!
 
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