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Severe Weather potential 9/8/12


weatherwiz

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The point, not all damaging MCS/wind events are classified as derechoes.

True

It's not necessarily a derecho pattern per se but it could perhaps meet the criteria.

It will probably turn out to be like many prior year cool season QLCS events. What makes tomorrow's interesting is IF scattered supercelss can develop out ahead of the forced line.

Nov 89? I like Wizs analogy.

Its good so is NOV 16-17 2010. I did a paper on this event.

In NOV 1989 there were actually 2 severe/tornado events in NYS one on the the 16th the other on the 20th.

I'm not that familiar with that event tho looking at NARR and the fact that there was a high risk over the south with the same system I don't see a ton of similarity. That was a ginormous trough. http://www.meteo.psu...1989/us1116.php

Here are some research papers on these events. I have them buried somewhere in my library if your interested I find them and send them to you.

LaPenta, K., and Barton, R. April,1993: The 20 November 1989 Northeast

Severe Weather Outbreak. Eastern Region Technical Attachment

No. 93-4A

Nemeth, J.S., Jr., and Farina, K., June, 1994: The Role of Jetstreaks in the

Tornadic Development of the November 16, 1989 over the Northeast

United States. Eastern Region Technical Attachment

No. 94-6A

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It's out, MDT, roughly the same size/location. 10% tor, 45% sig-hatched wind.

day1probotlk1200torn.gif

day1probotlk1200wind.gif

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1227 AM CDT SAT SEP 08 2012

VALID 081200Z - 091200Z

...THERE IS A MDT RISK OF SVR TSTMS PORTIONS CENTRAL/ERN

NY...CENTRAL/SRN VT...SWRN NH...CENTRAL/WRN MA...MUCH OF

CT...NJ...NRN DE...NERN MD...AND ERN PA...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING MDT RISK

AREA...FROM NRN NEW ENGLAND AND NY SWWD TO SC AND PORTIONS ERN GA...

...SYNOPSIS...

UPPER-AIR PATTERN OVER CONUS WILL FEATURE WRN MEAN RIDGING AND ERN

TROUGHING. LATTER WILL BE REINFORCED BY STG SHORTWAVE NOW ADVANCING

SEWD ACROSS LS...IA...AND CENTRAL PLAINS. PRIMARY 500-MB VORTICITY

CONCENTRATION ASSOCIATED WITH THIS PERTURBATION IS OVER WI ATTM.

ENHANCED VORTICITY FIELD IS FCST TO PIVOT CYCLONICALLY ACROSS LOWER

MI...NRN INDIANA AND OH THROUGH 08/18Z...THEN WEAKEN SOMEWHAT AND

EJECT NEWD TO NRN QUE BY 9/12Z. MEANWHILE...TRAILING/NARROW RIBBON

OF MAXIMIZED MID-UPPER LEVEL VORTICITY WILL MOVE GENERALLY SEWD OVER

SRN PLAINS...TN VALLEY/MID-SOUTH REGION...AND CENTRAL/SRN

APPALACHIANS...ALSO GRADUALLY WEAKENING. THESE PROCESSES WILL OCCUR

AS UPSTREAM TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER

NRN MB -- DIGS SEWD AND AMPLIFIES...REACHING LOWER GREAT LAKES AND

OH VALLEY BY END OF PERIOD.

SEASONALLY STG SFC COLD FRONT IS EVIDENT ATTM FROM LE SWWD ACROSS

OH...NEARLY COLLOCATED WITH SQUALL LINE FROM OH TO ARKLATEX

REGION...AND OTHERWISE SURGING SWD ACROSS NERN/W-CENTRAL TX AND

TRANS-PECOS REGION. VIGOROUS SFC CYCLOGENESIS SHOULD OCCUR ALONG

FRONT BY EARLY IN PERIOD OVER SERN ONT. RESULTING LOW THEN SHOULD

DEEPEN AND EJECT NEWD OVER NRN QUE...SLIGHTLY AHEAD OF LEADING

500-MB VORTICITY LOBE. BY 9/00Z...TRAILING COLD FRONT SHOULD REACH

ERN NY...DE RIVER VALLEY...WRN NC...NRN GA...AND SERN LA. FRONT

SHOULD MOVE OUT OF ERN MAINE AROUND END OF PERIOD...WHILE SRN

PORTION MOVES SEWD ACROSS ERN CAROLINAS AND SRN GA.

...NY/NEW ENGLAND SWWD TO SRN PIEDMONT REGION...

SCATTERED-NUMEROUS TSTMS ARE EXPECTED TO SWEEP EWD ACROSS THIS

REGION ALONG/AHEAD OF SFC FRONT. MAIN BAND OF SVR CONVECTION WILL

OFFER DENSE CONCENTRATION OF SVR/DAMAGING GUSTS...SOME OF WHICH MAY

REACH 65 KT...AS WELL AS A FEW TORNADOES...IN AND NEAR MDT RISK

AREA. TORNADOES ALSO ARE POSSIBLE WITH ANY OF SEVERAL STORM-SCALE

CIRCULATION REGIMES. HAIL RISK APPEARS TERTIARY IN IMPORTANCE.

COMBINATION OF INFLUENCES FROM AFOREMENTIONED MID-UPPER SHORTWAVES

WILL RESULT IN HEIGHT FALLS...TIGHTENING HEIGHT GRADIENTS

ALOFT...AND STRENGTHENING WIND FIELDS ALOFT OVER WARM SECTOR DURING

PERIOD OF DIURNAL HEATING. MEANWHILE...EXPECT LOW-LEVEL MOISTURE

TRANSPORT AND WAA THROUGHOUT PREFRONTAL MID-ATLC...WHERE MAIN BELT

OF DEEP ASCENT WILL ENCOUNTER RESERVOIR OF MID-60S TO LOW-70S F SFC

DEW POINTS. STG SFC DIABATIC HEATING IS EXPECTED FROM SERN CONUS

NEWD AT LEAST INTO DELMARVA/TIDEWATER REGION. CLOUD COVER MAY LIMIT

INSOLATION FARTHER N...THOUGH SUFFICIENT HEATING SHOULD OCCUR TO

WEAKEN CAP FAVORABLY OVER NYC AREA...LOWER HUDSON VALLEY AND SRN NEW

ENGLAND.

WIND-DAMAGE AND SPORADIC TORNADO THREAT WILL EXIST WITH PRIMARY

SQUALL LINE OVER MID-ATLC REGION...ERN NY AND WRN NEW ENGLAND.

TORNADO POTENTIAL SHOULD DIMINISH SWD INTO CAROLINAS...WITH DAMAGING

GUSTS STILL PRIMARY THREAT. SVR SHOULD BE MOST CONCENTRATED AROUND

BOW/LEWP FEATURES...EMBEDDED SUPERCELLS...AND RELATED

MESOCIRCULATIONS...GIVEN STRENGTH OF LOW-LEVEL SHEAR INTO WHICH THIS

CONVECTION WILL BE MOVING OVER MID-ATLC REGION. FCST SOUNDINGS SHOW

AREA OF 200-350 J/KG 0-1 KM SRH PRIOR TO FROPA...FROM NERN PA/NJ NWD

UP HUDSON VALLEY AND INTO WRN NEW ENGLAND. THAT AREA WILL LIE ON

NRN FRINGE OF STRONGEST BUOYANCY...WITH ENOUGH HEATING AND RICH

LOW-LEVEL THETAE TO YIELD 1000-2000 J/KG MLCAPE OVER WRN NY/WRN NEW

ENGLAND. BUOYANCY WILL INCREASE SSWWD TOWARD CHESAPEAKE BAY AND

BEYOND WHERE LOW-LEVEL SHEAR WILL BE WEAKER. OVERALL SVR THREAT

WILL BECOME LESS ORGANIZED AND SHORTER IN DURATION FROM GA SWWD TO

CENTRAL GULF COAST REGION.

IN MID-ATLC REGION...CONSIDERABLE UNCERTAINTY REMAINS REGARDING

NUMBER AND LONGEVITY OF RELATIVELY DISCRETE TSTMS AHEAD OF MAIN

LINE...WHICH WOULD POSE MORE ORGANIZED SUPERCELLULAR TORNADO RISK.

FCST BREADTH OF WARM SECTOR...LIKELIHOOD OF RELATIVELY WEAK MLCINH

BY EARLY AFTN...AND ENVIRONMENT CHARACTERIZED BY LARGE

HODOGRAPHS...SUGGEST SOME TSTMS MAY HAVE TIME TO MATURE INTO

DISTINCT SUPERCELLS. THEREFORE...RELATIVE MAX IN TORNADO

PROBABILITIES IS DRAWN FROM ERN NY/WRN NEW ENGLAND INTO SRN NEW

ENGLAND...ERN PA AND NJ.

OVERALL SVR POTENTIAL SHOULD DIMINISH AFTER DARK...THOUGH STG

DEEP-LAYER WINDS AND AT LEAST MRGL BUOYANCY WILL SHIFT EWD OVER MOST

OF NEW ENGLAND DURING LATE EVENING/OVERNIGHT HOURS. AS SUCH...SLGT

RISK PROBABILITIES ARE CARRIED EWD TO COAST...EXCEPT FOR MRGL RISK

OVER ERN MAINE LATE IN PERIOD.

..EDWARDS/LEITMAN.. 09/08/2012

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GFS is awful and NAM isnt much better, the total evolution is different with the best dynamics quickly escaping to the north, would be shocked if SPC didnt really shrink the MOD or take it out alltogether

Do you know anything about cool season severe events? Do you know what a LCHS severe weather event is?

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Do you know anything about cool season severe events? Do you know what a LCHS severe weather event is?

i dont consider this a cool season event with dews in the lower 70s and temps in the 80s. widespread low cape and high shear events are never a slam dunk, especially when I see the surface low proged to be so for NW and lifting out as quick as forecasted. I no longer see the S/W diving into the base of the trough as the NAM was showing earlier, hence the LLJ is no longer as strong as the NAM had say at 12z today.

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i dont consider this a cool season event with dews in the lower 70s and temps in the 80s.

Fall (sept 1 is the start of it meteorologically anyway) is a cool season. Oft times in Sept right up through March and April one can and does get severe wx with MINIMAL CAPE but high shear. This is a COOL SEASON event. Sometimes u won't even "see" any CAPE yet still get severe wx during these months. A decrease of theta-E with height in combo wiht high shear can work magic.

Time to move on....

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To be fair to Noreaster27, the shortwave does escape to the northeast faster on recent runs than what was previously shown, and the 0-1km helicity on the 00z NAM is weaker for southern areas than it was in last night's run. I definitely agree with issuing a 10% tornado, but I think it extends too far south and east.

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To be fair to Noreaster27, the shortwave does escape to the northeast faster on recent runs than what was previously shown, and the 0-1km helicity on the 00z NAM is weaker for southern areas than it was in last night's run. I definitely agree with issuing a 10% tornado, but I think it extends too far south and east.

Yeah there are many possible bust reasons for later today but noreaster is a troll.

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To be fair to Noreaster27, the shortwave does escape to the northeast faster on recent runs than what was previously shown, and the 0-1km helicity on the 00z NAM is weaker for southern areas than it was in last night's run. I definitely agree with issuing a 10% tornado, but I think it extends too far south and east.

Completely agree. Areas west of here CLEARLY have a strong signal of tornado potential, but I'm just not seeing it reaching down into central and even eastern SNE. Too far east. I can see a lot of potential hype and a huge bust. Will be interesting to see how the media plays it.

I've toyed with creating this graphic to compare with the SPC for verification. The red box is where I feel that a Tornado Watch may be warranted.

post-533-0-21872000-1347087594_thumb.png

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Boom

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN

CONNECTICUT...CENTRAL MASSACHUSETTS...EASTERN

MASSACHUSETTS...NORTHEASTERN MASSACHUSETTS...SOUTHEASTERN

MASSACHUSETTS...WESTERN MASSACHUSETTS...SOUTHERN NEW HAMPSHIRE AND

NORTHERN RHODE ISLAND.

.DAY ONE...TODAY AND TONIGHT.

DISCRETE STRONG TO SEVERE THUNDERSTORMS WILL BE POSSIBLE ALONG AND

AHEAD OF AN APPROACHING COLD FRONT FOR THE AFTERNOON PERIOD ACROSS

INTERIOR NEW ENGLAND. SOME OF THESE STORMS WILL HAVE THE POTENTIAL

OF PRODUCING TORRENTIAL DOWNPOURS...FREQUENT LIGHTNING...DAMAGING

WINDS...AND POSSIBLE TORNADOES.

INTO THE OVERNIGHT PERIOD...THE STRONG COLD FRONT WITH AN

ATTENDANT SQUALL-LINE IS EXPECTED TO SWEEP THROUGH THE REGION.

THERE IS THE RENEWED THREAT WITH THIS SQUALL-LINE OF TORRENTIAL

DOWNPOURS...FREQUENT LIGHTNING...AND DAMAGING WINDS.

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nice scud-nader on the cell in Btown tonight

post-992-0-14414800-1347071943_thumb.jpg

Beautiful picture.

This event is going to have typical cool-season event dynamics with >1000 J/kg CAPE likely over much of the warm sector. All systems go.

I don't get too jazzed over severe events as--due to their hit/miss nature, more often than not, most of us 'enjoy from the sidelines' Reading yhour enthusaism here though has me raising an eyebrow.

Completely agree. Areas west of here CLEARLY have a strong signal of tornado potential, but I'm just not seeing it reaching down into central and even eastern SNE. Too far east. I can see a lot of potential hype and a huge bust. Will be interesting to see how the media plays it.

I've toyed with creating this graphic to compare with the SPC for verification. The red box is where I feel that a Tornado Watch may be warranted.

post-533-0-21872000-1347087594_thumb.png

Congrats, Andy. :) I for one don't have a burning desire for a tornado to rip through my yard, so I don't mind that setting up west of NE. Just give me some good straight-line winds and I'll be fine.

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