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Potential Severe WX Outbreak Upstate NY & Vicinity


Quincy

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I think this deserves it's own thread. Everything appears to be coming together for a potential severe weather outbreak from the eastern Grear Lakes into upstate NY, VT and adjacent Canada by Tuesday. The GFS/NAM develop low pressure over the central Great Lakes Tuesday morning and eject the surface low ENE through the day. Impressive mid-level winds, even down to 850mb at 50+ knots in upstate NY combined with a very warm boundary layer and an EML point toward a very unstable setup. While an intense squall line may be possible, this setup could be ripe for supercell development as well. The NAM in particular shows some obscene soundings and hodographs indicating the potential for damaging winds, large hail and possibly tornadoes.

I'm on mobile, but I'll share one 18z NAM forecast hodograph for Plattsburgh, valid 18z Tuesday. Notice how 0-3km helicity is approaching a ridiculous value of almost 1000 m2/s2. Courtesy Earl Barker:

post-533-0-17826000-1378680670_thumb.jpg

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18z GFS/NAM 0-3 km EHI valid 21z Tuesday.

 

rzZMLky.gif

sVna8MM.gif

 

NAM (still pretty far out) is getting 2500-3000 J/kg SB/MLCAPE into that region which is certainly inflating the values above. That said, the timing when the s/w passes through the area will be crucial in terms of getting enough forcing/ascent to break the cap associated with aforementioned EML (for supercells, that is). The GFS appears more bullish on this idea than the NAM or the Euro in this respect. I think there will be at least one decent MCS with this series of waves in the 500 mb flow, though, especially given the impressive LLJ and strong instability.

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The NAM does seem a bit overdone with not only instability, but wind speeds as well. Either way, take a compromise of the NAM and GFS, and that's still a pretty impressive setup for upstate NY. With the Supercell Composite, once values start to get over 3 or 4 (orange is 4+), that's usually a pretty good indicator for me. The NAM is kind of wacky with values up around 12 or 13. Not to mention 0-3km SRH touches 1000 m2s2 in around 18z in some spots. Taken verbatim that would be a serious tornado setup. 

namNE_con_scp_051.gif

gfsNE_con_scp_051.gif

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The presence of an EML and a decent dew point-temperature spread (upper 80s/mid 60s) might lead to fairly high CIN values. As andyhb mentioned, this may be difficult to overcome.

18z GFS does look pretty ugly with a lot of CIN around. The NAM, which is kind of on its own, has fairly lower CIN.

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DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1254 AM CDT MON SEP 09 2013

VALID 101200Z - 111200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NRN/CNTRL NY AND NW

VT...

...NY/VT/NRN PA...

A SUBTLE SHORTWAVE TROUGH AND ASSOCIATED MID-LEVEL JET WILL MOVE EWD

ACROSS THE LOWER GREAT LAKES REGION ON TUESDAY. AT THE SFC...A LOW

IS FORECAST TO MOVE ACROSS SWRN ONTARIO TO NEAR THE NY-QUEBEC BORDER

BY TUESDAY AFTERNOON WITH A MOIST AXIS EXTENDING SWWD ACROSS NY INTO

NW PA. THE MODELS DEVELOP MODERATE INSTABILITY ALONG THIS CORRIDOR

AND SUGGEST THAT STORMS WILL INITIATE DURING THE AFTERNOON NEAR AND

TO THE SOUTH OF THE SFC LOW ACROSS NRN/CNTRL NY AND POSSIBLY IN NRN

PA. SEVERAL CLUSTERS OF ORGANIZED THUNDERSTORMS COULD PERSIST INTO

THE EARLY EVENING.

FORECAST SOUNDINGS AT 00Z/WED FOR SYRACUSE NY AND BURLINGTON VT SHOW

MLCAPE AROUND 2500 J/KG WITH 35 TO 40 KT OF 0-6 KM SHEAR. THIS

ENVIRONMENT SHOULD BE SUFFICIENT FOR SUPERCELL DEVELOPMENT IF CELLS

CAN REMAIN DISCRETE. SUPERCELLS SHOULD HAVE A THREAT FOR LARGE HAIL

AND DAMAGING WIND GUSTS. IN ADDITION...0-3 KM STORM RELATIVE

HELICITY AROUND 400 M2/S2 SHOULD ALSO BE FAVORABLE FOR A TORNADO

THREAT. IF THE PREFERRED MODE ENDS UP BEING LINEAR...THEN THE WIND

DAMAGE THREAT COULD BE DOMINANT. AT THIS POINT...WILL KEEP THE

SLIGHT RISK SMALL AND FOCUSED IN NRN NY WHERE THE COMBINATION OF

LARGE-SCALE ASCENT...INSTABILITY ARE VERTICAL SHEAR ARE FORECAST TO

BE MAXIMIZED.

..BROYLES.. 09/09/2013

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what time would you be leaving?  

Very early. Probably looking at about 3 hours of travel time to the Albany area and then need some time to decide if I go north or west. Maybe 6 a.m.? Not sure. It will still be a last-minute call to make sure it's worth it.

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If any discrete activity can develop tomorrow the potential for a strong tornado will be very possible

The shear params are decently forecast IMO but the CAPE values IMO are way too high. CIN could be underforecast too IMO

Things could be very volatile on Tuesday upstate. I'm reviewing more data, but it looks like I may be venturing north tomorrow to get in on this setup.

Let me know where you think and when. I'm thinking NEK of VT west to Tug for now best bet by 2-4 PM Tuesday afternoon

Still have more data to review, but I'm a little bit concerned that after the initial MCS, the boundary may be so far north that only extreme upstate NY and N VT get in on potential afternoon/evening activity tomorrow.

Think areas nearer the warm front have the best chances. Where it sets up will be tricky owing to possible early AM MCS' cold pool perhaps retarding the warm front's advancement to the north and northeast.

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Just a mess of a setup. Warm front has pushed into NY and a relatively healthy MCS is approaching from the NW. The overall movement is east, but one portion of the line is moving SE in the short-term.

With that said, the timing is too early to capitalize on daytime heating. While there could be a few marginally severe wind gusts, its movement is also ahead of better kinematic support.

Through the morning, it's still unclear how quickly the MCS will move out and what it leaves in it's wake. I am very skeptical about much convective redevelopment this afternoon. Definitely a tough forecast.

If the models are right, the area becomes very unstable, but may not have much forcing to work with. I have a feeling the models may be overdone on the instability, but we'll see.

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A nice sounding this morning at BUF with a very favorable wind profile, good lapse rates around 700 mb thanks to the EML and dry air above 500 mb. However, the cap will be tough to break as dew points over CNY/NNY look to stay in the mid/upper 60s. This is supported by both the latest HRRR run and the NSSL WRF which show virtually no activity over most of upstate NY through 00z tonight.

 

post-869-0-98995800-1378823102_thumb.gif

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Strong CAP in many places still, especially to the lee of mountains. Think CAP will break once sunsets and the upper height of the CAP layer cools more quickly when compared to very warm lower layers.

Here is the 18z Albany special raob for 9/11/2013 along with "weighted" severe weather params and CHAP

attachicon.gifSnap 2013-09-11 at 15.24.12.jpg

attachicon.gifSnap 2013-09-11 at 15.28.39.jpg

attachicon.gifSnap 2013-09-11 at 15.23.51.jpg

Very nice Andy... I agree!    might be a wild night.

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