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Convective potential today 9/29/11


weatherwiz

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A strong ULL which has been spinning off to our west these past several days will continue to slowly advance eastward. Around this ULL a few strong s/w will rotate through our region during the afternoon and evening. Out ahead of this ULL and in the warm sector temperatures have been fairly warm with high levels of humidity as dewpoints have been in the 60's to near 70F at times. This theme will continue tomorrow as well. While cloud cover should be a major issue tomorrow forecast soundings do indicate the potential for some scattered breaks in the clouds which would allow for some extra heating. With 925mb temps around +16-18C and 850mb temps around +12C this would yield to highs into the 80's this time of year with full heating/mixing. Unfortunately this will not be the case, however, temps should get into the lower to mid 70's across much of the region. This in combination with mid to upper 60's dewpoints and steepening lapse rates as the afternoon goes on should yield to some modest instability with Cape values reaching 500-800 J/KG and LI values in the -3C to -4C range.

Mid and upper level winds will be quite strong as well with ULJ of 100-125 knots just to our west placing us in the RFQ. Mid level jet is about 50-60 knots as well leading to vertical shear values of 45-55 knots!

With strong forcing/lift tomorrow and a negatively tilted system to go along with some modest instability the potential will exist for thunderstorms during the afternoon and evening hours. A few of the storms could become strong with gusty winds. Could also see some vivid lightning.

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Good post. I posted earlier tnt in the NYC thread of the same threat. I think we can see some svr. How much Idk, but some is possible. The shear is amazing!

Thanks!

Shear is certainly quite amazing tomorrow...hopefully we can at least generate just enough cape so updrafts are not being blown apart which can often happen in these really high shear/low cape setups. I do like the fact the system is negatively tilted though and that ML lapse rates do increase during the day. That ULJ streak of 100-125 knots too is pretty damn impressive, RFQ of that thing will do wonders for lift.

I kind of disagree though with the SPC where they say "Low-level flow is expected to remain modest throughout the day". I think LL winds will be more than just modest. Both the NAM and GFS are indicating as much as 20-30 knots at 925/850mb with the GFS increasing the LLJ up to 30-35 knots late in the afternoon! This is certainly impressive IMO, especially with the strong MLJ/ULJ's in place. Something to watch for too is which direction the LLJ aligns itself...some hints it may be more from the SE (500mb winds are southerly) so there could certainly be some helicity to deal with...something models may be underdoing.

Certainly not expecting an outbreak tomorrow given lack of higher instability but we certainly could see a few potent storms, especially down towards your way. I'd watch SE NY to LI...they seem to like these setups.

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I gotta say, I'm impressed with the s/w moving into the area today. Good height falls although winds kind of back with height. Not exactly sure what that would enhance...maybe gusty winds or perhaps HP cells? We might lack instability, however with cloud cover, but maybe western areas have the best shot.

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I gotta say, I'm impressed with the s/w moving into the area today. Good height falls although winds kind of back with height. Not exactly sure what that would enhance...maybe gusty winds or perhaps HP cells? We might lack instability, however with cloud cover, but maybe western areas have the best shot.

A 1pm TOR warning would be fun lol

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first tornado warning of the day in New York!

BULLETIN - EAS ACTIVATION REQUESTEDTORNADO WARNINGNATIONAL WEATHER SERVICE ALBANY NY1233 PM EDT THU SEP 29 2011THE NATIONAL WEATHER SERVICE IN ALBANY HAS ISSUED A* TORNADO WARNING FOR... EASTERN MONTGOMERY COUNTY IN EASTERN NEW YORK...* UNTIL 115 PM EDT* AT 1228 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO NEAR FONDA... MOVING EAST AT 10 MPH.* THE TORNADO WILL BE NEAR... FONDA BY 1255 PM EDT... TRIBES HILL BY 110 PM EDT... FORT JOHNSON BY 115 PM EDT...PRECAUTIONARY/PREPAREDNESS ACTIONS...

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Sun was out here briefly after about 3 hours of torrential rains. More coming up from NW CT and another area just NW of NYC could have some impact up here. Not sure if we have what it takes to get anything serious storm-wise. We had a fair amount of thunder/lightning at times in the earlier round, but nothing to get excited about (except for Paul--he'd be excited. :) )

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Had a decent storm about 15 minutes ago, some good c2g strikes and gusty winds, hazy sun now and tropical humidity

Congrats. Round 2 just starteed here--rumbles. Or maybe I'm hungry.........

Pretty significant temp differences between GC and northern ORH northward compared to the rest of SNE. Wonder what role that might play in the S-N movement of these bands.

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Nice squall line moving through here in Wrentham. Heavy rains. Wonder if there is any coastal front aiding in developing these?

Boy--it's so dark, you'd think it was nearly 7:00. Heavy rain, thunder. Nothing too exciting in the thunder department yet.

It really seems that there's been very little east of the CT river (not counting your cell, Bob). Is that the case or have I missed something?

EDIT: Right now, it's raining about as hard as I've ever seen it. Lightning now and nearby thunder.

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