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Sandy/Posttrop Phase Thread For PHL Area


phlwx

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A 946mb vortex hitting Long Island would equate to a strong category three hurricane although it will be extratropical at that time.

Category Three Hurricane

  • Maximum Sustained Wind Speed: 111-129 miles per hour
  • Damage Category: Extensive
  • Approximate Pressure: 964-945 mb
  • Approximate Storm Surge: 9-12 feet

...and it won't have Cat 3 wind with it despite that low of a pressure. The likelihood of this being tropical to Cape Cod is almost next-to-zero given its slow movement north and the baroclinic influence on it as it moves northward.

Irene had 958 pressure and was low cat 1 wind-wise as it was weakening/undergoing transition to nontrop.

Regardless, it'll be a nasty storm IF that scenario verifies...and to get a 940 mb hybrid entity at this latitude in October is awfully, awfully rare to pull off.

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EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD

329 PM EDT TUE OCT 23 2012

VALID 12Z FRI OCT 26 2012 - 12Z TUE OCT 30 2012

...POTENTIAL FOR MAJOR STORM OVER THE MID ATLANTIC & NORTHEAST

EARLY NEXT WEEK...

PRELIMINARY UPDATE...

UPDATED THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7

USING THE 00Z/23 EUROPEAN CENTRE ENSEMBLE MEAN, WITH A SMALL

INCORPORATION OF THE 00Z/23 EUROPEAN CENTRE DETERMINISTIC MODEL TO

LEND MORE DEFINITION TO THE SYNOPTIC GRADIENTS ACROSS THE NATION.

USED THE MOST RECENT FORECAST FROM THE NATIONAL HURRICANE CENTER

FOR THE TRACK OF TROPICAL STORM SANDY THROUGH DAY 5, WITH A CURVE

TO THE NORTHWEST DAYS 6 AND 7 BASED ON THE ECENS MEAN. THE 00Z/23

GEM GLOBAL CONTINUES TO CLUSTER WITH THE ECMWF FOR THE BEHAVIOR OF

SANDY ONCE IT TRANSITIONS TO AN EXTRATROPICAL SYSTEM, INDICATING

THAT THE CYCLONE GETS PULLED BACK TOWARD THE SHARP UPPER TROUGH

CLOSING OVER THE OHIO VALLEY. THE ECMWF AND GEM GLOBAL HAVE

SEVERAL RUNS OF CONTINUITY NOW WITH THE EVOLUTION OF THIS EVENT,

WITH THE DETERMINISTIC GFS LESS STABLE. THERE HAVE BEEN GFS

ENSEMBLE MEMBERS QUITE SIMILAR TO THE ECMWF/GEM CAMP FOR THE LAST

FEW DAYS OF MODEL CYCLES, PUTTING THE DETERMINISTIC GFS SOLUTIONS

IN A BROADER FRAMEWORK WITH THEIR TRACK OF SANDY WELL OVER THE

OPEN ATLANTIC. WILL BE UPDATING THE TRACK OF SANDY THROUGH DAY 5

FOR THE FINAL PACKAGE WITH THE ADVENT OF THE NEW NATIONAL

HURRICANE CENTER FORECAST, AND ITS BEHAVIOR AS AN EXTRATROPICAL

LOW THEREAFTER AS PER OUR HOTLINE COORDINATION.

FINAL...

ELECTED TO STAY THE COURSE BY KEEPING THE MAJOR EAST COAST STORM

IN PLAY FOR THE FINAL FORECAST. THE 12Z/23 DETERMINISTIC GFS SENDS

SANDY'S CIRCULATION OUT PAST BERMUDA BY THE END OF THE PERIOD,

WHILE THE 12Z/23 GEFS MEAN INCORPORATES IT ALONG THE EAST COAST IN

LINE WITH THE HPC MANUAL FORECAST. THE 12Z/23 GEM GLOBAL KEEPS

SANDY OUT OF REACH OF THE DIGGING TROUGH OVER NORTH AMERICA,

THOUGH LIKE THE LATEST GFS, IT IS PERHAPS BEST TO REGARD SUCH A

DETERMINISTIC SOLUTION AS A SLIGHTLY SOUPED-UP ENSEMBLE MEMBER.

THE 12Z/23 ECMWF STILL INCORPORATES AN EXTREMELY DEEP

POST-TROPICAL SANDY INTO THE MID-LEVEL PIVOT POINT OF THE POLAR

JET IN THE VICINITY OF LONG ISLAND EARLY NEXT TUESDAY, THE DYNAMIC

TRANSFER RESULTING IN A MINIMUM PRESSURE OF AT LEAST 932MB.

THEREIN LIES THE STORM'S MENACE- A POWERHOUSE CAPABLE OF WHIPPING

THE ATLANTIC INTO A FRENZY AND CHURNING UP DANGEROUS TIDES. OF

PARTICULAR NOTE IS THE COINCIDENCE OF THE FULL MOON ON SUNDAY,

OFTEN A SIGNIFICANT FACTOR IN HISTORICAL EVENTS. THE OCEAN EFFECTS

OF THE SYSTEM MAY STILL BE REALIZED EVEN IF POST-TROPICAL SANDY

DOES NOT MAKE LANDFALL IN THE UNITED STATES. BESIDES THE WIND, THE

OTHER SENSIBLE WEATHER THREAT IS HEAVY RAINS, WITH HEAVY SNOWS

POSSIBLE ON THE SOUTHWEST SIDE OF THE HYBRID CIRCULATION WHERE

CONTINENTAL POLAR AIR RUSHES ACROSS THE CENTRAL APPALACHIANS.

HAVE PREFERRED THE EUROPEAN CENTRE GUIDANCE FOR HANDLING OF THE

MAIN BAND OF WESTERLIES FOR SEVERAL DAYS NOW, ITS SYNOPTIC NUANCES

BEST SERVING THE CENTRAL AND WESTERN UNITED STATES WHERE THE FLOW

OPENS UP IN THE WAKE OF THE AMPLIFICATION OF THE EASTERN TROUGH.

CISCO

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What wind speeds we looking at though here in SE PA?

who knows its way to far out in time

post-105-0-27944200-1351022292_thumb.jpg

Agree with tombo it's too far out to say *what* will happen but this is the Euro verbatim on wind in kts. We've had much worse than this. NE gets plastered though.

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EC Ens through Sunday 2 AM is holding serve to last night's track.

Edit: through Monday night pretty much the same thinking from the mean...parallel to the coast, close brush with Cape Cod...but nudged a tiny bit east from 00z. Not a significant nudge east though.

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EC Ens through Sunday 2 AM is holding serve to last night's track.

Edit: through Monday night pretty much the same thinking from the mean...parallel to the coast, close brush with Cape Cod...but nudged a tiny bit east from 00z. Not a significant nudge east though.

to add to this coastalwx said their may be some spread west with the isobars bending back.

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A 946mb vortex hitting Long Island would equate to a strong category three hurricane although it will be extratropical at that time.

Category Three Hurricane

  • Maximum Sustained Wind Speed: 111-129 miles per hour
  • Damage Category: Extensive
  • Approximate Pressure: 964-945 mb
  • Approximate Storm Surge: 9-12 feet

Except it won't have anything like the pressure gradient of a hurricane so the winds will be much lighter. Of course, I mean much lighter in a relative sense.

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Forky said this in the sne thread

"the mean looks stronger and further west to me. that elongation at 144 hrs suggests maybe some landfalls in s nj"

by 162 there's a bit of a jump east (that was my comp point in the other post since that's Monday night/Tues AM) but what he said is accurate re: 144.

The mean is a good bit stronger as well...10 mb, maybe more.

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by 162 there's a bit of a jump east (that was my comp point in the other post since that's Monday night/Tues AM) but what he said is accurate re: 144.

The mean is a good bit stronger as well...10 mb, maybe more.

I dont mean to call you out or anything im just giving other view points also. Much appreciated the the ens info you shared.

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Except it won't have anything like the pressure gradient of a hurricane so the winds will be much lighter. Of course, I mean much lighter in a relative sense.

Understand that we won't be dealing with a hurricane at that point, but

Euro depicts winds of between 70 and 80 knots at 850 mb over parts of NJ at 168hrs. What would that translate to winds at the surface?

Thanks

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post-105-0-27944200-1351022292_thumb.jpg

Agree with tombo it's too far out to say *what* will happen but this is the Euro verbatim on wind in kts. We've had much worse than this. NE gets plastered though.

Hopefully those winds are accurate and PHL is operational... taking the kiddies to see Mickey Mouse and leave at 7AM on Tues.

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Understand that we won't be dealing with a hurricane at that point, but

Euro depicts winds of between 70 and 80 knots over parts of NJ at 168hrs. What would that translate to winds at the surface?

Thanks

i could see winds to strong tropical storm force maybe low end hurricane...inland i think best would be 50-60 max...in gusts

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