A look back at Hurricane Sandy (2012)

Sandy is no longer a hurricane, but the damage across the Mid-Atlantic and New England has been done. While Richmond was spared from the worst, we still had local impacts from the system.

October 30, 2012; 12:50 PM • by Weather Dan

Update #5 — October 30th, 12:50 PM

Above: A snapshot of the hint.fm wind map showing the surface wind pattern flowing into the low pressure center of the remnants of Hurricane Sandy.

Sandy made landfall around 8:00 PM EDT yesterday just north of Atlantic City, New Jersey. No doubt you’ve seen the many, many damage reports still coming in from North Carolina through New York and New England. The Associated Press is reporting that 34 people have died across several states, most in New York, as the storm has moved inland.

The Virginia Department of Emergency Management is reporting that there have been two storm-related fatalities in Central Virginia. The Federal Emergency Mangagement Agency (FEMA) has also announced that President Obama signed an emergency declaration for Virginia, making federal aid available to help the state respond to the storm.

The UK’s Daily Mail Online has a rather impressive collection of images from the storm.

Meanwhile, I’ve received several questions about the winds in Richmond overnight. Winds have been sustained between 15 and 20 miles per hour, with higher gusts to 35. Winds reached 45 mph overnight here in Blacksburg, and the Roanoke Regional Airport reported a 60mph gust yesterday evening.

Looking ahead: We’re definitely through the worst of the storm. While winds will continue to gust at times, we’re pretty much done with gusts above 30 mph. Power outages have been mostly sporadic across the Richmond metro, based on Dominion Virginia Power data. Northern Virginia wasn’t quite so lucky, as more than 86,000 customers are still without power as of this update. Most of the rain is done at this point, though on and off sprinkles and some moderate showers are possible through the rest of today. Temperatures will rebound beginning tomorrow and get back into the 50s and conditions become a bit more tranquil by the time we get to the weekend.

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Update #4 — October 29th, 7:35 AM

We’re seeing Sandy make a distinct northwest turn this morning, which is one of the final steps before it makes landfall later today along the Delmarva and southern New Jersey coasts. Based on reconnaissance from Air Force Hurricane Hunter aircraft this morning, it’s likely that Sandy will set the record for storm, tropical or not, with the lowest central pressure north of Cape Hatteras.

The Wall Street Journal has created an interactive viewer where you can compare the satellite imagery of Sandy to Irene last year. Sandy has been able to take advantage of some of the warm water of the Gulf Stream that its current over and has intensified slightly. Along with that, we’re seeing distinct cold and warm fronts set up around the storm, a sign that it’s undergoing the transition to an extratropical storm that I wrote about previously.

We’re under a high wind warning until 6am Tuesday. Winds currently are sustained at around 20 mph with gusts up to 30. This will increase through the day and into tonight, peaking with sustained winds between 30 and 40 mph with some isolated gusts in excess of 50 mph possible. Rain has moved in and will be a pretty permanent visitor until later tomorrow. In fact, as temperatures slip from the 50s this morning into the 40s and the 30s, especially outside the city, lots of folks will see snow carried from the extra-cold air in the mountains eastward and mixed in with the rain at times. I do not expect to see any snow accumulation to happen east of about I-77 in far southwest Virginia. It’s been falling here at my house for the last couple hours.

Be careful if you’re out today–as the rain falls and the ground continues to soften, we’ll likely see trees and some power lines begin to come down later today. By the time the sun comes up Tuesday, we’ll be through the worst of it.

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Update #3 — October 28th, 4:35 PM

We’re starting to see a lot of the pre-storm preparations fall into place now. The Virginia Department of Emergency Management has a continuously-updated shelter list available. Many school systems in the region have already closed for Monday, and Mayor Jones declared a state of emergency for the city. The Richmond Emergency Operations Center came online at 8 this morning. Richmond International Airport is reporting that nearly half of all flights for Monday have already been cancelled. If you’re planning on flying anywhere this week, check with your airline first. Amtrak has cancelled service in the Northeast Corridor, including most service on the east coast for Monday.

I’ve edited the post to include the latest advisory/track map and wind field map above. The headlines of the latest advisory paint a pretty telling picture:

…SANDY EXPECTED TO BRING LIFE-THREATENING STORM SURGE FLOODING TO
THE MID-ATLANTIC COAST…INCLUDING LONG ISLAND SOUND AND NEW YORK HARBOR…
…WILL BRING COASTAL HURRICANE WINDS AND HEAVY APPALACHIAN SNOWS…

The other big part of this story–and it’s one that the NHC alluded to in its headline above–is the snow threat for the higher parts of the Appalachians in North Carolina, Virginia, and West Virginia. The National Weather Service office in Charleston, WV, has posted blizzard warnings for southern West Virginia and parts of coal country in far southwestern Virginia.

THE NATIONAL WEATHER SERVICE IN CHARLESTON HAS ISSUED A BLIZZARD WARNING…WHICH IS IN EFFECT FROM NOON MONDAY TO 4 PM EDT WEDNESDAY.

* LOCATIONS…BEST CHANCES ACROSS HIGH TERRAIN…BUT CAN NOT BE RULED OUT IN THE VALLEYS.

* HAZARD TYPES…HEAVY WET SNOW…AND STRONG GUSTY WINDS.

* SNOW ACCUMULATIONS…RANGING FROM 1 TO 6 INCHES BELOW 2000 FEET…TO 1 TO 2 FEET ABOVE 3000 FEET.

* WINDS…INCREASING ON MONDAY WITH GUSTS OF 35 TO 45 MPH. SOME OF THE HIGHEST RIDGES COULD GUST TO NEAR 50 MPH.

* VISIBILITIES…WHITEOUT CONDITIONS AT TIMES.

* TIMING…RAIN WILL CHANGE TO SNOW OVERNIGHT SUNDAY NIGHT ACROSS HIGH TERRAIN…WITH SOME ACCUMULATIONS OCCURRING SUNDAY NIGHT AND EARLY MONDAY. HEAVIEST ACCUMULATIONS AND STRONGEST WINDS ARE EXPECTED MONDAY AFTERNOON INTO TUESDAY. LOWER ELEVATIONS MAY STRUGGLE TO CHANGE OVER TO SNOW. BEST CHANCES FOR CHANGING TO SNOW IN THE LOWER ELEVATIONS WOULD BE MONDAY NIGHT INTO TUESDAY.

* IMPACTS…THE HEAVY WET SNOW MAY BRING DOWN TREE LIMBS…CAUSING POWER OUTAGES OR FLUCTUATIONS. SNOW LOADING…OR THE WEIGHT OF THE SNOW…MAY CAUSE STRUCTURAL DAMAGE…INCLUDING COLLAPSING ROOFS. THE COMBINATION OF SNOW AND WIND WOULD LEAD TO REDUCED VISIBILITY.

I never in my life thought I’d see a hurricane that was also capable of producing snowfall amounts in excess of two feet.

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Update #2 — October 27th, 12:35 PM

Governor McDonnell declared a State of Emergency yesterday afternoon. This allows the Governor to mobilize the Virginia National Guard and Virginia Emergency Response Team. The Virginia Department of Emergency Management has also activated their statewide Emergency Operations Center, and set up a special Hurricane Sandy blog to provide updates about shelters and other local emergency response activities across the state.

Sandy is rolling right along. While the storm had weakened somewhat yesterday as dry air wrapped around the southern half of the storm. Overnight, it weakened to tropical storm status, but regained intensity this morning and is again a minimal hurricane.

So why all this attention to a “minimal hurricane?”

As I mentioned below, Sandy is going to begin undergoing what’s called an extratropical transition as it continues to move north. Tropical systems are driven by the heat released when warm, moist tropical air is cooled and the moisture condensed out. But this process requires waters warmer than roughly 79 degrees. The winter storms you’re likely familiar with – systems like nor-easters – are driven by the imbalance between warm and cold air wrapped around a center of low pressure. Even without Sandy’s presence, we’d likely be talking about a nor’easter developing over the next couple days; however, Sandy is going to infuse an extra hunk of warm, moist air that will make this situation much more dangerous.

The other key point right now is that Sandy has an extremely large wind field.

Here’s a look at Sandy’s wind field after emerging from the Bahamas just 24 hours ago:

The orange colors show the areas where Sandy’s winds were measured to be 39 mph or higher, and the dark red areas show winds 74 mph or higher. The distance from the center of the storm to the northern extent is about 275 miles.

Now here’s a look at the wind field this morning:

That distance from center to northern extent is now 475 miles. That’s big enough to cover all of Georgia, South Carolina, and North Carolina, and still have some left over. The first rain bands from the storm are already moving into Virginia Beach and Norfolk, and we’ll continue to see rain coverage expand over southeastern Virginia later today.

This is going to be a long-duration wind and rain event. Winds of 30-50 mph can be expected across eastern and central VA for majority of Sunday through Tuesday. Trees and power lines will come down, and widespread power outages will not be a surprise in the least. We’re in for a VERY sharp blast of cold air Tuesday. We could be looking at people with now power and dealing with multiple days of a high near 50 and lows in the 30s.

Keep this in mind while you’re making your preparations today. Conditions only go downhill from here.

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Update #1 — October 26th, 3:55 PM

We’re seeing a bit more agreement after the last couple rounds of model runs overnight and today.

The important takeaway here is that we’re not likely looking at landfall until probably Tuesday morning at the earliest, so we’ve still got about four days to go. To be able to offer any forecast at this point is pretty awesome in its own right. Secondly, don’t take anything as set in stone for this point. Note how large the cone of uncertainty is; any wobbles will change when landfall happens and exactly what impacts we see. Confidence in that part of the forecast will come over the weekend.

NOAA and the National Weather Service are also pulling out all the stops when it comes to forecasting this system. Weather balloons are normally launched twice a day at sites across the country, at noon and midnight GMT (that’s 8am/pm for us in Eastern Time). Beginning yesterday, they requested each office add two additional launches per day, at 6:00 AM and PM GMT (2:00 AM/PM EDT) from every launch site across the country. While special launches have been ordered for a certain set of office in support of high-impact events in the past, such as Hurricane Irene, this marks the first time that the special launches have been ordered for the entire continental US for a single event.

Additionally, you may have heard about some satellite troubles back in late September. GOES-13, the geostationary weather satellite dedicated to covering the eastern half of the US, had been shut down due to a degradation in service. GOES-14, -13’s younger, more advanced sibling, was brought out of on-orbit storage over South America and began providing coverage for -13 until it was restored to service just last week. While the plan was to return -14 to storage, it was reactivated and placed into a mode called Super Rapid Scan in order to get (literally) up-to-the-minute satellite imagery of the storm. While in normal operations, GOES satellites capture a new image roughly every half hour. In Super Rapid Scan operation, -14 is taking a new image every minute.

The advantage of SRSO- you get awesome imagery like this (animated GIF; takes a minute to load).

Given we’re still almost four days out I’m not going to update this continually over the weekend, but I’m going to try and include an update at least once daily. That may increase in frequency as we get closer to landfall.

Original Post

Thursday’s been a long day. I had a nice post about Sandy all planned out, but then we had forecast entities throw around terms like “Frankenstorm,” model runs all but assure the end of human habitation of the Mid-Atlantic states, and Twitter explode with chatter about the storm now that there are no more presidential debates to process.

So instead, I’ll let meteorologist Brad Panovich summarize the reasons why Sandy is such a difficult storm:

I missed the day of Meteorology Class where they talked about, Hurricane+Polar Vortex+Mega Trough+Blocking Pattern October Blizzard set-up.

— Brad Panovich (@wxbrad) October 26, 2012

The Weather Channel’s Bryan Norcross also adds in some excellent commentary in a blog post he wrote earlier tonight:

Isn’t it strange that a hurricane in the Bahamas would somehow turn into a monster mega-storm and slam into the Northeast at the end of October? Aren’t hurricanes supposed to weaken as they move north over cold water? What the hell is going on?

The answers are… yes, yes, and we’re not completely sure.

There’s a lot going there. But that, in essence, represents the major meteorological variables that are going into Sandy’s forecast.

Let’s start with what we know:

From the 11pm Thursday National Hurricane Center advisory:

LOCATION…25.3N 76.1W
ABOUT 15 MI…25 KM NNE OF ELEUTHERA ISLAND
ABOUT 185 MI…300 KM ESE OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS…90 MPH…150 KM/H
PRESENT MOVEMENT…NNW OR 335 DEGREES AT 13 MPH…20 KM/H
MINIMUM CENTRAL PRESSURE…968 MB…28.59 INCHES

Sandy had rapidly intensified before crossing Cuba last night, but is beginning to weaken again. Don’t be fooled by this; what we’re seeing is that Sandy is becoming a much broader storm – it’s more than 1500 miles across – and so its central circulation is not nearly as tight as it would be in a much smaller hurricane. Despite fighting dry air that is beginning to intrude into the center of the storm from the southwest, it is still poised to remain a hurricane through the weekend as it enjoys the energy benefits it will gain from an spending an extended period of time over the warm Gulf Stream.

The other big piece of this equation is a large mass of cold air (what Panovich called the “Mega Trough” above) working its way toward the south and east.

Long story short – the interaction between Sandy and this trough will mean that Sandy will begin to evolve from a tropical system into a mid-latitude system, driven by sharp changes in temperature over area rather than by the heat engine of warm, tropical waters. Despite this change in characteristics, the indications are that it’s going to be a VERY large storm with impacts along most of the Eastern Seaboard all at once. While there’s still quite a bit of variability among the global modeling systems regarding the storm’s track, it’s size means that the center of the storm shouldn’t be the focal point. Tracks are easy to show on a map, but in reality, if you’re on the Atlantic side of the Appalachians, you’re going to be in the way of this system.

What’s Next

Here’s a look at some (not all) of the model tracks for Sandy as the storm progresses.

You can see the big trend is that of a track to the northwest, then a move back toward the northeast, and then a hard turn to the west before making landfall somewhere between Virginia and Rhode Island. It’s hard to say exactly where landfall will be at this point, but the trend over the last few model cycles has been toward the southern end of the envelope, roughly from NYC south to Virginia.

Impacts

The exact timing will vary with the storm’s track, but we can expect to start feeling the effects of Sandy as the storm gets close late Saturday. If the turn comes closer to the south, then these may be accelerated somewhat.

• Wind: Gusts likely in excess of 30mph for an extended period from Sunday through Tuesday and into Wednesday
• Rain: Several inches of rain are expected to fall during the same timeframe. We’ve been dry for the year, but that looks to change
• Coastal flooding: Below the fall line, storm surge from Sandy will lead to widespread heavy surf and coastal flooding. In addition, a full moon means that tides will be running one to two feet above normal, further enhancing the flooding threat.
• All this will lead to some pretty hefty erosion along beaches and barrier islands.

Sandy will also funnel a significant amount of cold air moving in beginning Sunday. Temperatures will almost continually plummet over this period, dropping 20-30 degrees by Wednesday. We’re going to go from highs near 80 to a high around 50…if we’re lucky. The worst case scenario also brings a few flakes of snow into the picture over this period as well.

There’s still quite a bit of time for all this to play out, and I’ll keep posting updates as we get data back. Spend Friday and Saturday preparing, clearing out anything that might back up your gutters or storm drains. Stock up on the basics and prepare yourself for power outages; remember that you’re going to want to keep warm in some exceptionally cold air that’s going to move in through the first half of next week. Gas up the car. Grab some cash from the ATM–it’s hard to run credit cards when the power is out. And if you don’t have one, grab a car charger for your phone.

This storm has the potential to be a very nasty one. With any luck, we won’t need these things, but this isn’t one to mess around with. Sandy has already claimed 21 lives in the Caribbean and has the potential to be the United States’ next billion-dollar storm. Take it seriously, please.

 

(Top: A vivid image of the center of Hurricane Sandy as captured by the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the Suomi NPP satellite. Credit: NOAA/NASA)

October 30, 2012 12:50 PM 1 5 updates