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Mt. Holly Severe Threats


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At what point does a squall line get deemed an actual derecho? I keep reading in various places this thing is moving 50-65 mph hour.

I can't see how PHL and ILG miss out on the line.....seems to be south of guidance and definitely moving SSE. Batten down the hatches when it gets here......I'm pretty sure I actually don't want to see a derecho roll through my backyard after witnessing firsthand what the one down south did a few weeks ago.

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Wow they considered High Risk on the last Day 1 outlook:

...WIDESPREAD DAMAGING WIND EVENT/POTENTIAL DERECHO APPEAR TO BE

UNFOLDING ACROSS PARTS OF THE NORTHEAST...

...OH TO SRN NEW ENGLAND...

ADJUSTED MODERATE RISK TO ALONG AND AHEAD OF INITIAL QLCS IN SWRN NY

TO ERN OH AND UPSTREAM DEVELOPMENT OCCURRING BACK IN WRN OH.

ALTHOUGH SEVERE WIND GUSTS HAVE YET TO BE MEASURED BY ANY ASOS/AWOS

OBSERVATIONS...50-55 KT EWD MOVEMENT HAS BEEN NOTED WITH THIS

INITIAL LINE AND 18Z PIT/OKX RAOBS ARE CERTAINLY SUPPORTIVE OF FAST

ELY PROPAGATION. CONSIDERED UPGRADE TO HIGH RISK BUT RELATIVELY

MODEST MID/HIGH-LEVEL LAPSE RATES SAMPLED IN REGIONAL 18Z RAOBS

SUGGEST MODERATE RISK APPEARS MOST APPROPRIATE ATTM.

NEVERTHELESS...NUMEROUS TO WIDESPREAD COVERAGE OF DAMAGING WINDS IS

LIKELY AS THE NUMBER OF BOWING SEGMENTS INCREASE WITH AN ASSOCIATED

THREAT OF ISOLATED INTENSE WIND DAMAGE AND BRIEF TORNADOES.

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* TORNADO WARNING FOR... SOUTHERN LUZERNE COUNTY IN NORTHEAST PENNSYLVANIA...

* UNTIL 600 PM EDT.

* AT 502 PM EDT... NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 9 MILES WEST OF EAST BERWICK... MOVING EAST AT 40 MPH.

* THE STORM CAPABLE OF PRODUCING THE TORNADO WILL BE NEAR... NESCOPECK AND EAST BERWICK BY 515 PM EDT... BEACH HAVEN BY 520 PM EDT... CONYNGHAM BY 530 PM EDT... DRUMS AND WEST HAZLETON BY 535 PM EDT... FREELAND... WOODSIDE-DRIFTON AND DRIFTON BY 540 PM EDT...

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Statement as of 5:55 PM EDT on July 26, 2012

The NWS Storm Prediction Center has issued a

Severe Thunderstorm Watch for portions of

District of Columbia

Delaware

Maryland

southern New Jersey

northern Virginia

West Virginia Panhandle

coastal waters

Effective this Thursday afternoon and Friday morning from 555 PM

until 100 am EDT.

Hail to 1.5 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 55 miles northwest

of Staunton Virginia to 50 miles east southeast of Dover

Delaware. For a complete depiction of the watch see the

associated watch outline update (wous64 kwns wou8).

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 524... ww 525... ww

526... ww 527...

Discussion... trailing portion of expansive qlcs ongoing from the

lower Hudson Valley into upper OH valley is expected to progress

sewd across watch area this evening. Ambient inflow air mass is hot

and moist with MLCAPE of 2000-3000+ j/kg. When coupled with a

unidirectional... wly wind field... setup will remain supportive of

forward propagation of qlcs with an attendant risk for damaging

winds and some hail.

Aviation... a few severe thunderstorms with hail surface and aloft

to 1.5 inches. Extreme turbulence and surface wind gusts to 60

knots. A few cumulonimbi with maximum tops to 550. Mean storm

motion vector 30035.

... Mead

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MESOSCALE DISCUSSION 1613

NWS STORM PREDICTION CENTER NORMAN OK

0504 PM CDT THU JUL 26 2012

AREAS AFFECTED...SOUTHERN/EASTERN PA TO SOUTHEAST NY/NYC METRO AND

SOUTHERN NEW ENGLAND

CONCERNING...TORNADO WATCH 525...

VALID 262204Z - 262330Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 525 CONTINUES.

SUMMARY...TORNADO WATCH 525 CONTINUES UNTIL 01Z AND SEVERE TSTM

WATCH 527 CONTINUES UNTIL 03Z.

SERIOUS CONCERN EXISTS FOR WIDESPREAD SWATHS OF WIND DAMAGE INTO THE

EARLY/MID EVENING HOURS WITHIN WATCHES 525/527. ISOLATED TORNADOES

ALSO REMAIN A CONCERN ESPECIALLY ACROSS SOUTHEAST NY AND ADJACENT

PARTS OF EASTERN PA/NORTHERN NJ...WITH WIDESPREAD WIND DAMAGE

OTHERWISE EXPECTED TO STEADILY SPREAD EAST-SOUTHEASTWARD TOWARD THE

COAST WITH A FAST-MOVING SEVERE MCS/DERECHO.

DISCUSSION...WELL-ORGANIZED QUASI-LINEAR CONVECTIVE SYSTEM /QLCS/

CONTINUES TO STEADILY PROGRESS EAST-SOUTHEASTWARD...FROM NEAR THE

SOUTHEAST NY/NORTHEAST PA BORDER VICINITY SOUTHWESTWARD INTO

SOUTH-CENTRAL PA...WITH THE FASTEST-MOVING BOWING /NORTHEASTERN/

PORTION OF THE LINE MOVING AS FAST AS 45-50 KT. LATEST SUBJECTIVE

SURFACE ANALYSIS REFLECTS A PRESSURE FALL-RISE COUPLET...WITH MODEST

QLCS-LEADING PRESSURE FALLS...AND A 20-25 DEG F COLD POOL ALONG WITH

3 MB/2 HR PRESSURE RISES ACROSS PA IN THE TRAILING STRATIFORM WAKE

REGION OF THE QLCS. COINCIDENT WITH A GRADUAL STRENGTHENING OF MEAN

FLOW OVER THE PAST FEW HOURS...LATEST WSR-88D VWP DATA FROM STATE

COLLEGE IS INDICATIVE OF 50 KT WINDS BETWEEN 2-6 KM IN ASSOCIATION

WITH THE QLCS WAKE REGION.

WITH ADDITIONAL FORWARD PROPAGATION/ACCELERATION AND RESULTANT

BOWING LIKELY...OF FURTHER CONCERN IS THAT THE AIRMASS CONTINUES TO

STEADILY WARM LATE THIS AFTERNOON /AS OF 21Z/ IN TANDEM WITH

CLOUD-FREE SKIES AND THE NORTHEASTWARD ADVANCEMENT OF A WARM FRONT

TOWARD FAR SOUTHEAST NY/NYC METRO AND SOUTHWEST NEW ENGLAND. THESE

THERMODYNAMIC TRENDS...PRESENCE OF THE WARM FRONT...AND EXISTING

ORGANIZED NATURE OF THE MCS/COLD POOL SUGGESTS A VERY HEIGHTENED

WIND DAMAGE/SOME TORNADO POTENTIAL INTO REMAINING PARTS OF SOUTHEAST

NY/NYC METRO/SOUTHWEST NEW ENGLAND AND ADJACENT PARTS OF EASTERN PA

AND NJ.

..GUYER.. 07/26/2012

post-1201-0-03275500-1343340830_thumb.gi

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