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Hurricane Sandy - LIVE - Meteorological Discussion


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Sandy will be getting into the right entrance region of the strong jet streak downstream of the main trough today, as well as staying in the left exit region of a weaker subtropical jet streak. It should also stay or cross over the gulf stream within 24 hours, allowing it to maintain the warm core.This should support some more intensification.

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BULLETIN

HURRICANE SANDY ADVISORY NUMBER 25

NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012

1100 AM EDT SUN OCT 28 2012

...SANDY EXPECTED TO BRING LIFE-THREATENING STORM SURGE FLOODING TO

THE MID-ATLANTIC COAST...INCLUDING LONG ISLAND SOUND AND NEW YORK

HARBOR...

...WINDS EXPECTED TO BE NEAR HURRICANE FORCE AT LANDFALL...

SUMMARY OF 1100 AM EDT...1500 UTC...INFORMATION

-----------------------------------------------

LOCATION...32.5N 72.6W

ABOUT 250 MI...400 KM SE OF CAPE HATTERAS NORTH CAROLINA

ABOUT 575 MI...930 KM S OF NEW YORK CITY

MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H

PRESENT MOVEMENT...NE OR 45 DEGREES AT 14 MPH...22 KM/H

MINIMUM CENTRAL PRESSURE...951 MB...28.08 INCHES

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IN ADDITION...HURRICANE-FORCE WINDS ARE EXPECTED ALONG PORTIONS OF

THE COAST BETWEEN CHINCOTEAGUE VIRGINIA AND CHATHAM MASSACHUSETTS.

THIS INCLUDES THE MIDDLE AND UPPER CHESAPEAKE BAY...DELAWARE

BAY...AND THE COASTS OF THE NORTHERN DELMARVA PENINSULA...NEW

JERSEY...THE NEW YORK CITY AREA...LONG ISLAND...CONNECTICUT...AND

RHODE ISLAND.

TROPICAL STORM FORCE WINDS ARE EXPECTED NORTH OF CHATHAM TO

MERRIMACK RIVER MASSACHUSETTS...THE LOWER CHESAPEAKE BAY...AND

SOUTH OF CHINCOTEAGUE TO DUCK NORTH CAROLINA...THE NORTHERN

ENDPOINT OF THE TROPICAL STORM WARNING.

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HURRICANE SANDY DISCUSSION NUMBER 25

NWS NATIONAL HURRICANE CENTER MIAMI FL AL182012

1100 AM EDT SUN OCT 28 2012

DATA FROM NOAA AND AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT

MISSIONS THIS MORNING HAVE REVEALED NO SIGNIFICANT CHANGES TO THE

INTENSITY OR OVERALL STRUCTURE OF SANDY...EVEN THOUGH SATELLITE

IMAGERY INDICATES A BANDING EYE FEATURE IS TRYING TO FORM AND THE

CENTRAL PRESSURE HAS BENE AS LOW AS 951 MB. THE AIRCRAFT DATA...

ALONG WITH DATA FROM SHIPS...BUOYS...AND SURFACE OBSERVATION SITES

INDICATE...HOWEVER...THAT THE WIND FIELD HAS CONTINUED TO EXPAND.

HURRICANE-FORCE WINDS NOW EXTEND OUT TO ABOUT 150 N MI TO THE

SOUTHWEST...AND THE 50-KT WIND RADII HAVE ALSO INCREASED TO ABOUT

200 N MI IN THAT SAME QUADRANT. BASED ON THE FLIGHT-LEVEL AND

SFMR-ADJUSTED SURFACE WINDS...THE INITIAL INTENSITY IS BEING

MAINTAINED AT 65 KT.

THERE HAVE BEEN SOME TRACK WOBBLES BUT THE INITIAL MOTION ESTIMATE

IS 045/12 KT. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS

FORECAST TRACK OR REASONING. SANDY WILL CONTINUE TO INTERACT WITH A

STRONG NEGATIVELY TILTED SHORTWAVE TROUGH LOCATED OVER THE

TENNESSEE VALLEY THAT WILL CONTINUE TO MOVED EASTWARD TOWARD THE

U.S. EAST COAST OVER THE NEXT 48 HOURS. AS THE TROUGH UNDERCUTS

SANDY TO ITS SOUTH...THE HURRICANE IS EXPECTED TO LIFT

NORTHEASTWARD AND THEN NORTHWARD OVER THE NEXT 24 HOURS...FOLLOWED

BY A TURN TO THE NORTHWEST AND POSSIBLY WEST-NORTHWEST UNTIL

LANDFALL OCCURS WITHIN 48 HOURS OR SO. THE OFFICIAL FORECAST TRACK

IS SIMILAR TO THE PREVIOUS ADVISORY TRACK AND LIES DOWN THE MIDDLE

OF THE TIGHTLY PACKED GLOBAL AND REGIONAL MODEL GUIDANCE.

THE VERTICAL SHEAR IS FORECAST TO DECREASE IN THE 12 TO 36-HOUR

PERIOD AND SANDY IS EXPECTED MAINTAIN A SMALL AREA OF DEEP

CONVECTION NEAR THE CENTER WHILE THE HURRICANE REMAINS OVER SSTS

GREATER THAN 25C. AS A RESULT...THERE IS STILL SOME POTENTIAL FOR

SANDY TO INTENSIFY SLIGHTLY AS A TROPICAL CYCLONE...ESPECIALLY WHEN

IT WILL BE TRAVERSING THE WARM GULFSTREAM TONIGHT. BY 36 HOURS...

THE GLOBAL MODELS SHOW SOME DEEPENING OF THE CYCLONE...WHICH IS

UNDOUBTEDLY DUE TO STRONG BAROCLINIC FORCING...AND A TRANSITION TO

AN EXTRATROPICAL CYCLONE IS EXPECTED PRIOR TO LANDFALL. IT IS

IMPORTANT TO NOTE THAT THIS TRANSITION WILL NOT DIMINISH THE

OVERALL IMPACTS OF THIS DANGEROUS WEATHER SYSTEM. AFTER LANDFALL...

THE GLOBAL MODELS...AND THE OFFICIAL INTENSITY FORECAST...INDICATE

RAPID WEAKENING IS EXPECTED.

AS NOTED IN PREVIOUS ADVISORIES...TO AVOID A HIGHLY DISRUPTIVE

CHANGE FROM TROPICAL TO NON-TROPICAL WARNINGS WHEN SANDY BECOMES

POST-TROPICAL...THE WIND HAZARD NORTH OF THE TROPICAL STORM WARNING

AREA WILL CONTINUE TO BE CONVEYED THROUGH HIGH WIND WATCHES AND

WARNINGS ISSUED BY LOCAL NATIONAL WEATHER SERVICE OFFICES.

FORECAST POSITIONS AND MAX WINDS

INIT 28/1500Z 32.5N 72.6W 65 KT 75 MPH

12H 29/0000Z 34.0N 71.3W 65 KT 75 MPH

24H 29/1200Z 36.4N 70.7W 70 KT 80 MPH

36H 30/0000Z 38.7N 72.9W 70 KT 80 MPH

48H 30/1200Z 40.1N 76.3W 60 KT 70 MPH...POST-TROP/EXTRATROP

72H 31/1200Z 41.3N 77.2W 40 KT 45 MPH...POST-TROP/EXTRATROP

96H 01/1200Z 44.5N 76.8W 30 KT 35 MPH...POST-TROP/EXTRATROP

120H 02/1200Z 46.6N 73.4W 25 KT 30 MPH...POST-TROP/EXTRATROP

$$

FORECASTER STEWART

post-32-0-52255200-1351436433_thumb.gif

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Now showing 30 foot waves...

Station 41001

NDBC

Location: 34.561N 72.631W

Date: Sun, 28 Oct 2012 14:50:00 UTC

Winds: ENE (70°) at 36.9 kt gusting to 48.6 kt

Significant Wave Height: 29.5 ft

Dominant Wave Period: 12 sec

Mean Wave Direction: E (84°)

Atmospheric Pressure: 28.87 in and falling

Air Temperature: 75.9 F

Water Temperature: 79.9 F

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Now showing 30 foot waves...

Station 41001

NDBC

Location: 34.561N 72.631W

Date: Sun, 28 Oct 2012 14:50:00 UTC

Winds: ENE (70°) at 36.9 kt gusting to 48.6 kt

Significant Wave Height: 29.5 ft

Dominant Wave Period: 12 sec

Mean Wave Direction: E (84°)

Atmospheric Pressure: 28.87 in and falling

Air Temperature: 75.9 F

Water Temperature: 79.9 F

The history graph is revealing: http://www.ndbc.noaa.gov/show_plot.php?station=41001&meas=sght&uom=E&time_diff=-4&time_label=EDT

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Friendly reminder to use 300mb maps for the polar jet and 200mb maps for the subtropical jet (STJ doesn't shop up very well at 300).

Thanks for this mention. Its important to note that the three jet streams in the atmosphere (subtropical, polar, arctic) are relative to the location of the tropopause in the atmosphere. Thus typically the subtropical jet will always be higher aloft than the polar jet, just like the polar jet will also be higher aloft than the arctic jet. This is why Dynamic tropopause maps look they way they do, which three distinct gradients near the jet cores.

Example: When Sandy was still located in the Caribbean

2zekxnr.png

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Took a wobble SE, but the eye is popping. Possible sign shear is lowering.

I agree, inner core looks way less sheared than yesterday. Low topped convection has organized into coherent bands all around the core. Could be the beginning of the warm seclusion region taking on tropical cyclone like characteristics.

This sequence of events has been similar to the 'Perfect Storm' around this time of the year in 1991, except the pressures are way lower.

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The shear over the system is around 25 knots so shear is not prohibitively strong for convection to continue to fire and develop around the center. In addition, in around 18 hours as the system makes it turn, it will briefly move over the Gulf Stream, which still has some moderate oceanic heat content for this time of the year. As long as the shear remains low to moderate (a likely assumption) this could allow Sandy to have a bit of a resurgence in deeper convection near the center. It wouldn't be that difficult to see Sandy deepen another 10 or so hPa, which would put the pressure at around 940, which is what several of the more agressive guidance members have been depicting.

s6rxhw.gif

sgr2tt.gif

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URNT12 KNHC 281739

VORTEX DATA MESSAGE AL182012

A. 28/17:21:30Z

B. 32 deg 42 min N

071 deg 59 min W

C. 700 mb 2670 m

D. 47 kt

E. 173 deg 26 nm

F. 237 deg 69 kt

G. 138 deg 127 nm

H. 953 mb

I. 10 C / 3047 m

J. 12 C / 3050 m

K. 12 C / NA

L. SPIRAL BAND

M. NA

N. 12345 / 7

O. 0.02 / 1 nm

P. AF302 2018A SANDY OB 16

MAX FL WIND 78 KT S QUAD 16:17:30Z

MAX FL TEMP 13 C 199 / 8 NM FROM FL CNTR

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