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Hurricane Sandy kills 21, heads towards the U.S.

By: Dr. Jeff Masters, 3:34 PM GMT on October 26, 2012

Hurricane Sandy plowed through the Bahama Islands as a powerful Category 2 hurricane with 105 mph winds yesterday, but high wind shear has destroyed the hurricane's eyewall and reduced Sandy to Category 1 strength, with 80 mph winds. Satellite loops show that the low-level center of Sandy is now exposed to view, with most of the storm's heavy thunderstorm activity pushed to the north side by strong upper level winds from the south-southwest. Cuban state media is reporting that eleven people were killed on Cuba, and damage was heavy, with thousands of homes damaged or destroyed. It was Cuba's deadliest hurricane since Category 5 Hurricane Dennis killed sixteen people in 2005. Damage was also substantial on Jamaica, where one person was killed, and power was knocked out for 70% of the island's residents. Nine deaths have been reported in Haiti due to flooding, and heavy rains from Sandy continue there this morning.


Figure 1. Morning satellite image of Sandy.

Forecast for Sandy
Wind shear is expected to remain a high 30 - 55 knots for the next four days, as Sandy interacts with a trough of low pressure to its west. The high shear should keep Sandy from intensifying the way most hurricanes do--by pulling heat energy out of the ocean. However, the trough approaching from the west will inject into Sandy what is called "baroclinic" energy--the energy one can derive from the atmosphere when warm and cold air masses lie in close proximity to each other. This transition will reduce the hurricane's peak winds, but strong winds will spread out over a wider area of ocean. This will increase the total amount of wind energy of the storm, keeping the storm surge threat high. This large wind field will likely drive a storm surge of 3 - 6 feet on Monday and Tuesday to the right of where the center makes landfall, on the mid-Atlantic or New York coasts. These storm surge heights will be among the highest ever recorded along the affected coasts, and will have the potential to cause hundreds of millions of dollars in damage.

The latest set of 00Z (8 pm EDT) and 06Z (2 am EDT) computer model runs still have wide differences in the timing and landfall location for Sandy. The ECMWF has been very consistent in its handling of Sandy, and continues to predict that Sandy will hit Delaware or Maryland on Monday afternoon--basically the same forecast it has had for three days. Our other top model for forecasting hurricane tracks, the GFS, has been more inconsistent, and predicts a landfall on Long Island, New York on Tuesday afternoon.


Figure 2. Predicted 5-day precipitation total for Hurricane Sandy as forecast by the 2 am EDT October 26, 2012 run of the HWRF model. A wide swath of 8 - 16" of rain (dark yellow colors) is predicted for North Carolina, Virginia, and Maryland. Image credit: Morris Bender, NOAA/GFDL.


Figure 3. A customized version of the Weather Research and Forecasting (WRF) Model run by Weather Decision Technologies (http://www.wdtinc.com/) computed the precipitation expected to fall from Sandy over the 5-day period ending at 5 am EDT Tuesday, October 30. Using the predicted precipitation, METSTAT, Inc. (http://www.metstat.com) computed the Extreme Precipitation Index (EPI) to represent how unusual the storms' precipitation is expected to be in terms of an average recurrence interval ("return period"). Several swaths of 24-hour rainfall amounts that one would expect to recur on average every 100 years (red through pink colors) are predicted. The recurrence interval statistics were computed based on precipitation frequency estimates from NOAA Atlas 14 Volume 2, published in 2004 (http://dipper.nws.noaa.gov/hdsc/pfds/.) Metstat does not supply the forecast EPIs for free, anyone can monitor the real-time EPI analysis (observed) at: http://metstat.com/solutions/extreme-precipitation-index-analysis/

Severe impacts likely in the U.S.
Sandy's expected landfall along the mid-Atlantic coast is likely to be a billion-dollar disaster. Sandy should bring sustained winds of 50 - 60 mph with gusts over hurricane force to a large section of coast, and the storm may be moving slowly enough that these conditions will persist for a full 24 hours. With most of the trees still in leaf, there will be widespread power outages due to downed trees. Sandy is expected to have tropical storm-force winds that extend out more than 400 miles from the center, which will drive a much larger storm surge than its winds would ordinarily suggest. The latest H*Wind analysis from NOAA's Hurricane Research Division put the destructive potential of Sandy's winds at 2.1 on a scale of 0 to 6, and the destructive potential of the storm surge much higher, at 4.2 on a scale of 0 to 6. The full moon is on Monday, which means astronomical tides will be at their peak for the month, increasing potential storm surge flooding. With Sandy's strongest winds expected to last at least 12 hours near the time of landfall, the peak storm surge will affect the coast for at least one high tide cycle, and possibly two. This will greatly increase the potential for storm surge damage and coastal erosion. If Sandy hits Long Island, as the GFS model predicts, the storm surge will be capable of over-topping the flood walls in Manhattan and flooding portions of the New York City subway system. Fresh water flooding from heavy rains is also a huge concern. Rainfall amounts of 5 - 10 inches will occur over several hundred mile-long swath of coast, with isolated amounts of 15 inches possible. Fortunately, soils are dry and river levels are low over most of the threatened region, which should keep Sandy's river flooding lower than that experienced last year during Hurricane Irene. Nevertheless, Sandy is shaping up to be a historic storm for the mid-Atlantic and Northeast U.S. that has few precedents.

Jeff Masters

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Quoting SLU:
"Valerie"



That's 384 hours out? Although, the GFS has sniffed out trouble more than once this season.
Center is basically void of heavy precipitation. All the weather is being blown to the north by wind shear.
Definately having issues hanging onto tropical characteristics.
I saw some great looping visualizations of Sandy's interaction with the trough in the comments to yesterday's post. It was a white outline of the US with maroon shading and isobar lines delineating the two masses merging. I believe it was called the 500mb Vorticity. Does anyone know where I can find that? Specifically for the Euro model if available.
Quoting will40:


you are right about the final point but where she comes ashore is south of the last tracks

Okay I see now, again, thank you. I have learned a lot over the last couple days just from reading the comments on this blog. I'm in Binghamton, NY, which got hit really hard with flooding last year so we're making preparations and keeping our fingers crossed. I expect this to have less of an impact, but better to prepare for the worst and hope for the best I suppose. Will get all my "extended power outage" shopping done this weekend.
Quoting Losttsol:
Now you've got me going. I can't stop laughing about the one guy at the "Canadian Hurricane Center". It's way out in a shack on Newfoundland somewhere. He's just minding his own business and all of a sudden the hurricane alarms go off and a red light starts spinning. He's so startled that he spits his coffee out all over his keyboard (he was watching Storm Stories reruns online).


Laughing over here too! You have to be a Canadian to appreciate that vision you just gave us! Here I thought he worked in Happy Valley, Goose Bay! ;)(Just kidding)

Seriously though. I'm originally from Eastern Ontario and to see those kinds of warnings go up in my hometown is quite worriesome.

My only hope is that everyone in the affectd areas are taking heed and making their preparations. The old expression "Been there, done that, and didn't get a t-shirt...."

Lindy
FLOOD ADVISORY
NATIONAL WEATHER SERVICE SAN JUAN PR
458 PM AST FRI OCT 26 2012

PRC007-025-035-041-045-057-109-123-262300-
/O.NEW.TJSJ.FA.Y.0419.121026T2058Z-121026T2300Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
CAGUAS PR-CAYEY PR-CIDRA PR-COMERIO PR-GUAYAMA PR-PATILLAS PR-
SALINAS PR-AGUAS BUENAS PR-
458 PM AST FRI OCT 26 2012

THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED AN

* URBAN AND SMALL STREAM FLOOD ADVISORY
FOR THE FOLLOWING MUNICIPALITIES...

IN PUERTO RICO
CAGUAS...CAYEY...CIDRA...COMERIO...GUAYAMA...PATIL LAS...SALINAS
AND AGUAS BUENAS

* UNTIL 700 PM AST

* AT 456 PM AST...DOPPLER RADAR INDICATED NUMEROUS SHOWERS AND
ISOLATED THUNDERSTORMS IN THE ADVISORY AREA. THIS RAINFALL IN
ADDITION TO THE RAINFALL THAT HAS ALREADY OCCURRED...WILL LEAD
TO RAPID RISES ON SMALL STREAMS AND CREEKS...AS WELL AS MINOR
FLOODING ALONG ROADWAYS...THROUGH AT LEAST 7:00 PM AST.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 1825 6601 1800 6611 1803 6628 1809 6623
1828 6616

$$

23
508. SuzK
Quoting Patrap:
947 is impressive for the Size Gro.

Sheesh, a Whopper.

That's going to move a lot of water somewhere.

This is bad,bad, bad, Mojo.


That last model had it almost on top of us here in NE PA. I am concerned to say the least. We bought a transistor radio today, and batteries. Gas for the generator and wood pellets to burn too, because I also read something about a blizzard on the backside hitting us. We are in the Chesapeake Watershed, in a flood zone. Interesting times. Thank god the water table is quite low!
College here just closed campus starting sunday at 11am. is that too late?
As many as 7,300 customers were without power because of outages today, in Brevard County, FL. Currently there is 800.
BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE SAN JUAN PR
608 PM AST FRI OCT 26 2012

THE NATIONAL WEATHER SERVICE IN SAN JUAN HAS ISSUED A

* FLASH FLOOD WARNING FOR...
THE FOLLOWING MUNICIPALITIES

IN PUERTO RICO
CAGUAS
CAYEY
CIDRA

* THIS WARNING INCLUDES ALL RIVERS...STREAMS AND TRIBUTARIES WITHIN
THE WARNED AREA.

* UNTIL 900 PM AST

* AT 603 PM AST...DOPPLER WEATHER RADAR INDICATED SHOWERS AND
ISOLATED THUNDERSTORMS WITH TORRENTIAL RAINFALL AFFECTING PARTS OF
THESE MUNICIPALITIES. RADAR ESTIMATES INDICATE THAT 2 TO LOCALLY 3
INCHES OF RAIN HAVE ALREADY FALLEN...ESPECIALLY OVER CAYEY AND
CAGUAS AND IT CONTINUED TO RAIN. ADDITIONAL RAINFALL OF 1 TO 2
INCHES IS EXPECTED. FLASH FLOODING IS LIKELY...ESPECIALLY ALONG RIO
CAGUITAS IN CAGUAS

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING.
IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY.
RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE
PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS
SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY
AUTOMOBILE. TURN AROUND...DONT DROWN.

&&

LAT...LON 1821 6618 1819 6613 1828 6603 1819 6602
1813 6606 1812 6609 1812 6610 1808 6615

$$

BCS

ADDITIONAL INFORMATION CAN BE FOUND AT /USE LOWER CASE LETTERS/:
HTTP://WWW.WEATHER.GOV/SANJUAN
512. MahFL
Convection is firing over the center, could the shear be slacking off a bit ?
Calm as a cucumber in Seaside Heights, New Jersey...
The Jersey Coast is realizing probably its worst fear.
Amazing...just had a rain shower from sandy here in St. Maarten who's center is a thousand miles away.
517. LRC
Have not followed discussion close, so I do not know if this has been discussed at all.
There have been others who have noticed that in the last few years Greenland seems to have a cold high parked over it for extended periods of time. The issue has been brought up because of loss of Arctic sea ice seems to have lost the Arctic its normal high.
If that is the case could the influence of that stationary high mean that the normal hurricane tracks may start changing in that they could either wonder around like Hurricane Michael or do strange tracks like Sandy.
Combine that with a slower but more wildly moving jet stream, you may not get as many high category storms, but you could get ones creating far more damage because they stall out.
All times in GMT. Derived from NHC_ATCF data for HurricaneSandy @ 27Oct.12pm
Since the previous mapping, 27Oct.6am's StormStatus has been re-evaluated&altered from TropicalStorm to Hurricane
28.1n76.9 has been re-evaluated&altered
28.1n77.0w-28.8n76.8w are now the most recent positions

HNC-CapeHatteras :: MYR-MyrtleBeach :: GGE-Georgetown :: MHH-GreatAbaco

The southernmost dot on the longest line is H.Sandy's most recent position

The longest line is a straightline projection through H.Sandy's 2 most recent positions to its closest approach to an inhabited coastline
26Oct.06pm: H.Sandy had been headed for passage midway between CapeRomainHarbor and YawkeySouthIslandReserve (bottom,GGEdumbbell)
27Oct.12am: H.Sandy had been headed for passage over MyrtleBeach (left,MYRblob
27Oct.06am: H.Sandy had been headed for passage 40.1miles(64.5kilometres)ESEast of CapeHatteras (right,straightline top blob)
27Oct.12pm: H.Sandy had been heading for passage 38.4miles(61.9kilometres)ESEast of CapeHatteras

Click this link to the GreatCircleMapper for a larger map with more info