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SNE severe/convective thread IX...or whatever number we're on


weatherwiz

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They seem to do better later in July into August (based on my recollection) than the interior does

Well maybe not better, but SSTs are warmer now so the marine layer is less pronounced. Euro is really slow with the front which would favor areas more north, but today's convection and leftover clouds or boundaries will probably have a say on where the front ends up tomorrow.

Looking at things today, I can't rule out a line of storms moving into nrn MASS. 500mb temps are warm though which will limit things.

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.NEAR TERM /UNTIL 6 PM THIS EVENING/...

---1300Z UPDATE---

REMNANTS OF MCS MOVEING ACROSS NORTHERN PORTIONS OF CWA THIS

MORNING. ALTHOUGH THIS WILL WORK THE AIRMASS OVER A LITTLE

BIT...IT WILL NOT CHANGE THINGS TOO MUCH. MODIFIED 12Z SOUNDING

SHOWS ROUGHLY 3000J/KG WORTH OF CAPE TO WORK WITH THIS AFTERNOON.

AS BOUNDARY GETS NEARER TO CWA...SHEAR WILL INCREASE ALSO. THIS

LOOKS TO BE SETTING UP TO BE A BUSY DAY WITH SEVERE WEATHER THIS

AFTERNOON AND INTO THIS EVENING. ADJUSTED THE FORECAST TO INCREASE

POPS SIGNIFICANTLY AS IT APPEARS MORE LIKELY NOW THAT SHOWERS AND

THUNDERSTORMS WILL BE AROUND TODAY. ALSO ADJUSTED TEMPERATURES

SLIGHTLY TO ACCOUNT FOR CURRENT TRENDS.

Bumped Pop to 80% chance of severe today and this evening

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I have to give the American models credit, they've been fairly consistent with the Weds. threat for some time (fropa timing aside). But the idea of unidirectional flow near the MA/CT border with a slightly veered profile further north has been there. Agree with Wiz and others that a bowing segment ripping eastbound on the Pike is a concern right now.

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Still a little iffy here as the 12z NAM and SREFs seem to highlight more CT and RI.

They seem to kick things off quickly. The strong probability of low level frontogenesis and high CAPE with marginal shear suggests a high likelihood that there will be sporadic screw zones throughout the corridor. But, it also suggests the potential for SIG SVR in narrow corridors where clusters become organized.

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They seem to kick things off quickly. The strong probability of low level frontogenesis and high CAPE with marginal shear suggests a high likelihood that there will be sporadic screw zones throughout the corridor. But, it also suggests the potential for SIG SVR in narrow corridors where clusters become organized.

It's going to be a high CAPE day so the fuel is there. Kind of weird to see the euro so slow and the NAM and SREFs much faster. I wonder if part of it is a result of what happens late today or this evening. If the timing is right, the combo we have is classic for coastal areas. Light winds at the surface, yet good shear aloft. You don't see that too often. I haven't looked too hard down by you, but nrn NJ at least is under the gun.

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It's going to be a high CAPE day so the fuel is there. Kind of weird to see the euro so slow and the NAM and SREFs much faster. I wonder if part of it is a result of what happens late today or this evening. If the timing is right, the combo we have is classic for coastal areas. Light winds at the surface, yet good shear aloft. You don't see that too often. I haven't looked too hard down by you, but nrn NJ at least is under the gun.

Down here we lose a bit of the wind shear but we have a ton of CAPE with hardly any cap, There will likely be a large cluster of thunderstorms that swiftly move southeastward through most of the area with narrow corridors of SIG SVR. Big CAPE / low shear is a classic setup in mid-July for NJ.

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Down here we lose a bit of the wind shear but we have a ton of CAPE with hardly any cap, There will likely be a large cluster of thunderstorms that swiftly move southeastward through most of the area with narrow corridors of SIG SVR. Big CAPE / low shear is a classic setup in mid-July for NJ.

Yeah, I agree with you. I like this area for a more organized/sig potential given the amount of CAPE/shear here. There's a narrow area where things are juxtaposed quite well.

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Down here we lose a bit of the wind shear but we have a ton of CAPE with hardly any cap, There will likely be a large cluster of thunderstorms that swiftly move southeastward through most of the area with narrow corridors of SIG SVR. Big CAPE / low shear is a classic setup in mid-July for NJ.

I have a bias for this living near the water, but big CAPE usually means big fun here. You can get all the good stuff that strong shear has to often if CAPE is substantial enough. I don't mind low shear as it usually favors this area. NJ down to DC is the CAPE capitol of the northeast.

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Yeah, I agree with you. I like this area for a more organized/sig potential given the amount of CAPE/shear here. There's a narrow area where things are juxtaposed quite well.

The 850mb winds do pick up throughout the day but never really get into a good territory for widespread severe. I wouldn't rule out some supercells at initiation for southern New England into NE PA but likely non-tornadic.

There will probably be at least 2 corridors of screw zones if the NAM solution is correct between PA and MA.

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I have a bias for this living near the water, but big CAPE usually means big fun here. You can get all the good stuff that strong shear has to often if CAPE is substantial enough. I don't mind low shear as it usually favors this area. NJ down to DC is the CAPE capitol of the northeast.

Momentum CAPE bombs will likely blast eastward down this way and bring some localized high wind gusts to someone.

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The GFS develops a little seabreeze/meso low overhead too tomorrow. Pretty robust over this region fwiw. Shear almost weakens slightly during the day before increasing again, but the increase in shear may be the model response to the developing convection. Not a bad jet structure with some divergence over srn areas at 200mb.

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MESOSCALE DISCUSSION 1480

NWS STORM PREDICTION CENTER NORMAN OK

1102 AM CDT TUE JUL 17 2012

AREAS AFFECTED...UPSTATE NY...NRN NEW ENGLAND

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 171602Z - 171700Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...CONVECTIVE INITIATION IS EXPECTED N OF THE INTERNATIONAL

BORDER BY 17-18Z. THE W-E ORIENTED LINE OF STORMS WILL THEN PROGRESS

SWD INTO UPSTATE NY AND NRN NEW ENGLAND...WITH A PREDOMINANT THREAT

OF DMGG WINDS AND PERHAPS A FEW TORNADOES. HAIL WILL BE POSSIBLE

WITH ANY INITIALLY DISCRETE STORMS THAT CAN DEVELOP. A WW APPEARS

LIKELY BY 17-18Z.

DISCUSSION...INITIAL STRATUS FROM EARLIER CONVECTION IS QUICKLY

PROGRESSING EWD...WITH CLEARING AND AMPLE SURFACE HEATING

CONTRIBUTING TO WELL ABOVE NORMAL TEMPERATURES. LOCATIONS ACROSS

CNTRL AND UPSTATE NY THAT HAVE CLEARED HAVE ALREADY ACHIEVED

FORECAST HIGHS APPROXIMATELY FOUR HOURS EARLIER THAN MODEL CONSENSUS

FORECAST. AS SUCH...MODERATE SURFACE-BASED DESTABILIZATION IS

RAPIDLY OCCURRING...PARTICULARLY NEAR THE INTERNATIONAL BORDER WHERE

SURFACE DEW POINTS REMAIN IN THE UPPER 60S TO LOWER 70S. UPSTREAM

SOUNDINGS ACROSS MI SUGGEST STEEPER MID-LEVEL LAPSE RATES WILL

ADVECT EWD ACROSS THE NORTHEAST...WHILE A DEEP LAYER STRENGTHENING

OF WINDS OCCURS AROUND THE BASE OF A HUDSON BAY TROUGH. ATTM...IT

APPEARS CONVECTIVE INITIATION WILL OCCUR ALONG A COLD FRONT THAT HAS

BEEN REINFORCED BY DIFFERENTIAL HEATING RESIDING ACROSS NRN ME...SRN

QC AND ON. A LINE OF BOWING SEGMENTS AND POSSIBLE SUPERCELLS SHOULD

THEN PROGRESS SWD...FAVORABLY TIMED WITH STEEP LAPSE

RATES/INCREASING DEEP LAYER SHEAR.

..HURLBUT/MEAD.. 07/17/2012

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URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 489

NWS STORM PREDICTION CENTER NORMAN OK

125 PM EDT TUE JUL 17 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

WESTERN MAINE

NEW HAMPSHIRE

NORTHERN NEW YORK

VERMONT

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 125 PM UNTIL

900 PM EDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 15 MILES SOUTHWEST

OF WATERTOWN NEW YORK TO 40 MILES EAST SOUTHEAST OF BERLIN NEW

HAMPSHIRE. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 488...

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND

INTENSITY THIS AFTERNOON AHEAD OF COLD FRONT ADVANCING SEWD INTO THE

REGION. THE COMBINATION OF STEEPENING MIDLEVEL LAPSE RATES FROM THE

W AND BOUNDARY LAYER DEWPOINTS IN THE 60S WILL YIELD MLCAPE VALUES

APPROACHING 1000-1500 J/KG. WHEN COUPLED WITH A STEADILY

STRENGTHENING WLY...DEEP-LAYER WIND FIELD...SETUP WILL SUPPORT

SUPERCELLS AND BOWING STRUCTURES CAPABLE OF DAMAGING WINDS...LARGE

HAIL...AND PERHAPS A TORNADO.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 32030.

...MEAD

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The GFS develops a little seabreeze/meso low overhead too tomorrow. Pretty robust over this region fwiw. Shear almost weakens slightly during the day before increasing again, but the increase in shear may be the model response to the developing convection. Not a bad jet structure with some divergence over srn areas at 200mb.

It's too bad the jet isn't a little more robust and farther south:

post-532-0-06754200-1342546556_thumb.gif

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