Superstorm Sandy and the importance of polar orbiting satellites in forecasting
On the 23rd of October, the 18th named storm of the 2012 Atlantic hurricane season, Tropical Storm Sandy, was born in the Central Caribbean. As is common for late-season storms in the Caribbean, Sandy moved northwards across Cuba. The official forecasts from the National Hurricane Center issued on October 23 called for Sandy to turn to the northeast after crossing Cuba, and head into the Central Atlantic. This forecast was based on the output from five of our top six computer models, which all predicted that an upper-level low pressure system in the Central Atlantic would be strong enough to pull Sandy northeastwards. However, the global weather forecast model run by the European Center for Medium-Range Weather Forecasts (ECMWF) showed a disturbing possibility: the upper-level low pressure system in the Central Atlantic would not be strong enough to turn Sandy to the northeast. The hurricane would instead get caught up in the flow associated with a trough of low pressure approaching the U.S. East Coast, and Sandy would get slung into New York or New Jersey on October 29. While the ECMWF model was the best performing model for tracking Atlantic hurricanes in both 2010 and 2011, and had done very well again so far in 2012, the American GFS model had outperformed the ECMWF model several times during the 2012 season. NHC elected to discount the ECMWF forecast for Sandy as an outlier, and went with the forecast from the GFS and other models. By October 25, it was clear that the ECMWF model had the right idea all along. More models were now showing the turn towards New York, and the official NHC forecast now called for Sandy to make landfall in New York or New Jersey on October 29. The ECMWF model's early forecast of a track for Sandy into the Northeast was critical for allowing additional time for residents to prepare for arrival of the devastating storm. So what enabled the ECMWF model to make such an excellent forecast for Sandy, six days in advance?
Figure 1. This image uses the model output from the ECMWF experiment, showing where Sandy was predicted to be located five-days out with the normal satellite data inputs into the model (left) and without any polar-orbiting satellite data (right). Both position and intensity forecasts were affected--Sandy stays out to sea without the polar-orbiting satellite data, and the closer isobar lines encircling the storm also imply a more organized and stronger system. Image credit: NOAA.
Polar satellite data: a key to ECMWF model success
The ECWMF has a very sophisticated technique called "4-D Var" for gathering all the current weather data over the Earth and putting the data on a 3-dimensional grid that is then used as the initial "reality" of the current weather for the model to use for its forecast. The old expression, "garbage in, garbage out" is a truism for weather forecast models. If you don't properly characterize the initial state of the atmosphere, the errors you start off with will grow and give a lower-quality forecast. Data from geostationary satellites, which sit continuously at one spot above the globe, are easy to assimilate, and all the models use this data. However, the ECMWF model's superior technique used to assimilate the initial data allows inclusion of data from a large number of polar-orbiting satellites, which the other models cannot do as well. Polar-orbiting satellites orbit Earth at an altitude of 540 miles twice per day, circling from pole to pole. Their data is difficult to use, since the it is only available twice per day at each spot on the Earth, and the time of availability is different for each location. According to an email I received from Jean-Noël Thépaut, the chief of the Data Division of the Research Department at the European Center for Medium-Range Weather Forecasts, the ECMWF model uses data from at least fourteen polar orbiting satellites: N-15, N-19, N-19, N-17 (ozone SBUV instrument only), Metop-A, AQUA, NPP (ATMS instrument only), AURA (ozone OMI data only), F-17, TRMM (TMI data), COSMIC, GRACE-A, TERRASAR, and the GPSRO data on top of METOP-GRAS. The data of most importance is the data collected in the infrared and microwave wavelengths, as well as atmospheric density data obtained via GPS radio occultation (as a polar orbiting satellite goes over the horizon, the GPS signals from the satellite get bent by Earth's atmosphere, with the amount of bending proportional to the density of the atmosphere. This GPS Radio Occultation data is gathered from eight polar orbiting satellites, and fed into both the ECMWF and GFS models.) You can find a nice summary of the impacts of polar orbiting satellite data on weather prediction models at this link.)
Figure 2. Forecast track error for four of our top models used to predict Hurricane Sandy, for their runs that began at 00Z October 25, 2012. By this time, the GFDL model had joined the ECMWF in predicting that Sandy would make landfall in Southern New Jersey in five days. The GFS and HWRF models made good 1 - 3 day forecasts, but failed to anticipate Sandy's north-northwestward turn towards the U.S. coast. Image credit: Morris Bender, NOAA/GFDL.
As originally reported by the Washington Post's Capital Weather Gang, then confirmed in a NOAA press release, a study done by ECMWF research scientist Tony McNally found that if the ECMWF model did not have all of the data from the fourteen polar orbiting satellites, the five-day forecast of the model for Hurricane Sandy would have shown Sandy missing the Northeast U.S. This brings up a concern, since the U.S. polar orbiting satellite program is behind schedule. As explained by Andrew Freedman of Climate Central, the program is plagued by mismanagement, billions in cost overruns, and technical development challenges. The next polar orbiting satellite is not scheduled to be launched until 2017, and one or more of the existing polar orbiting satellites are expected to fail before then. This will result in a degradation of our ability to observe and predict the weather, and may result in poorer forecasts for storms like Hurricane Sandy. Given that the ECMWF model used data from fourteen polar orbiting satellites, the failure of just one satellite may not have made a significant difference in its forecast for Sandy. But if we lose several of these key satellites by 2017, our hurricane forecasts in 2017 may be worse than they were in 2012. To figure out how to cope with the loss of satellite-derived data, NOAA is conducting a Gap Risk Study that seeks ideas from researchers and the public on how NOAA can preserve the quality of its weather model forecasts in the event of the failure of one or more polar orbiting satellites in the coming years.
Figure 3. A tanker rests on the southern shore after being swept onto land by a storm surge due to Superstorm Sandy, Friday, Nov. 2, 2012, in the Staten Island borough of New York. (AP Photo/ John Minchillo)
Links
Eric Berger of the Houston Chronicle has an interview with Jean-Noël Thépaut, chief of the Data Division of the Research Department at the European Center for Medium-Range Weather Forecasts, on why the European model did so well with Hurricane Sandy.
Jeff Masters
Reader Comments
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Jersey Shore revolution begins, as FEMA releases new flood maps
A revolution is likely coming to the New Jersey Shore, and the federal government just fired the first shot.
The Federal Emergency Management Agency released advisory flood maps yesterday, which they hope will serve as a guideline for how nearly 200 communities should rebuild stronger after Hurricane Sandy’s devastation. The maps (see below) are the first change to New Jersey’s federal flood maps in more than two decades, and show a coastline far more vulnerable to flooding than previously thought -- as Sandy proved in the worst way.
FEMA’s message is clear: If you’re going to rebuild, build higher and stronger.
"These are decisions communities are going to have to make together," said Bill McDonnell, a representative for FEMA’s Office of External Affairs in Trenton. "All we’re trying to do is provide them with the best data available, and we certainly hope townships use this information to enhance their existing ordinances and rebuild smarter."
If towns along New Jersey’s barrier islands and the Raritan Bay shore adopt the guidance, it will mean a vastly different looking coastline, but one that will be better protected from future storms. An analysis of FEMA and Sandy storm surge data shows in places like Ortley Beach and Union Beach, many homes would need to be raised more than four feet to avoid serious damage from an identical storm. In some locations closest to the water, it could mean raising homes a full-story.
-- more at link, click on headline.
Also some very interesting comments at the link.
Its the Climate Change Blog Wash
If it was August or September there would be blood on the walls here with that image ... folk freaking out ..Good Job its January lol
This was the 00Zs, the 12Z runs will be out soon.
It has always been there just doesnt seem to attract many but the diehards on either side . Dont often go there !!!
(In response to last night's news article post Link )
Hi txjac, this is a very good question and you are right, it's not real clear in the article how they make the determination the meteorite is from Mars. You made me curious too and I found this clearer explanation on the Life in the Universe website:
How Do We Know that the Meteorites Come from Mars?
Basically they use a combination of analysis of the composition, trapped gases, and process of elimination. Thanks for asking that question. It's never a bad thing to ask for more info and not take things at face value.
In other news...after watching lots of green on the radar but no rain reaching the ground, it's finally coming down today and has been for a few hours. Nice and light and steady. There is actually some standing water in the pasture. Woot! You know it's been too dry when you actually find it fun to be squooshing around in the mud to feed the cows. :-)
Models are showing the NAO plummeting after January 16. Look for a major arctic outbreak across most of the United States after that time.
Its doesnt seem to be a real soaker though convection seems light
Wow, thanks for the answer. Now you have me curious as to other space rocks from different planets. I'll have to look in to it.
Rain is glorious ...even the dog is just laying around being lazy. My pit/boxer sissy doesnt like going out in the rain
6z GFS 216 hours:
12z at 192 hours:
Euro at 192 hours, not nearly as strong as the GFS and farther east but still something there:
12Z GFS for 00Z Wednesday (@ 84 hours)
00Z ECMWF for 00Z Wednesday (@ 96 hours)
12Z GFS for 00Z Thursday (@ 108 hours)
00Z ECMWF for 00Z Thursday (@ 120 hours)
GFS forecasts over a foot of snow.
These storm tracks are extremely favorable for several outbreaks as we head into February and March though.
Make the most of it ... I think it will be grey soon enough
NATIONAL WEATHER SERVICE MELBOURNE FL
1059 AM EST SAT JAN 5 2013
AMZ550-552-555-570-572-575-FLZ041-044>047-053-054 -058-059-064-141-
144-147-052100-
COASTAL VOLUSIA-FLAGLER BEACH TO VOLUSIA-
BREVARD COUNTY LINE 20 NM TO 60 NM OFFSHORE-FLAGLER BEACH TO VOLUSIA-
BREVARD COUNTY LINE OUT TO 20 NM-INDIAN RIVER-INLAND VOLUSIA-MARTIN-
NORTHERN BREVARD-NORTHERN LAKE-OKEECHOBEE-ORANGE-OSCEOLA-
SEBASTIAN INLET TO JUPITER INLET 20 NM TO 60 NM OFFSHORE-
SEBASTIAN INLET TO JUPITER INLET OUT TO 20 NM-SEMINOLE-
SOUTHERN BREVARD-SOUTHERN LAKE-ST. LUCIE-VOLUSIA-
BREVARD COUNTY LINE TO SEBASTIAN INLET 20 NM TO 60 NM OFFSHORE-
VOLUSIA-BREVARD COUNTY LINE TO SEBASTIAN INLET OUT TO 20 NM-
1059 AM EST SAT JAN 5 2013
.NOW...
HIGH PRESSURE OVER THE SOUTHEAST U.S. WILL PRODUCE NORTH TO NORTHEAST
WINDS 10-15 MPH. ISOLATED SHOWERS OVER THE ATLANTIC WATERS WILL
APPROACH THE MARTIN AND SAINT LUCIE COASTS AND MAY PRODUCE A BRIEF
SHOWER. SOUTHWEST FLOW OVERRUNNING THE SHALLOW NORTH WINDS AT THE
SURFACE IS PRODUCING LOW CLOUDS ACROSS LAKE AND VOLUSIA COUNTIES THIS
MORNING. THIS ISENTROPIC LIFT IS EXPECTED TO WEAKEN THIS AFTERNOON
AND ALLOW TEMPS TO RISE NEAR 70 NORTH OF ORLANDO WITH SOME
SUNSHINE.ALTHOUGH SKIES ARE MOSTLY SUNNY THIS MORNING ACROSS MUCH OF
EAST CENTRAL FLORIDA...MORNING CAPE SOUNDING SHOWS SUFFICIENT LOW
LEVEL MOISTURE TO PRODUCE AN INCREASE IN CUMULUS CLOUDS AS SURFACE
HEATING TAKES PLACE...RESULTING IN PARTLY CLOUDY SKIES THIS
AFTERNOON.
A STATIONARY FRONT LIES ACROSS EXTREME SOUTH FLORIDA BUT WILL BEGIN
TO LIFT BACK NORTH AS A WARM FRONT TONIGHT AND SUNDAY. RAIN CHANCES
WILL INCREASE LATE SUNDAY INTO SUNDAY NIGHT.
&&
ADDITIONAL DETAILS...INCLUDING GRAPHICS ARE AVAILABLE ONLINE AT:
HTTP://WWW.SRH.NOAA.GOV/MLB/BLOG.PHP
I read about it in the NWS Eastern region yesterday.....
its supposed to be really good...
dual-pol technology has been proving itself time and time again during weather events that have both challenged NWS forecasters, but also armed them with improved confidence, thanks to the new technology.
From Ready weather Nation
CAROLINA...SOUTHWEST VIRGINIA...WEST CENTRAL VIRGINIA AND SOUTHEAST
WEST VIRGINIA.
.DAY ONE...TODAY AND TONIGHT.
A WINTRY MIX OF LIGHT SLEET AND LIGHT SNOW WILL BE POSSIBLE LATE
THIS EVENING THROUGH EARLY SUNDAY MORNING. PATCHY FREEZING DRIZZLE
WILL ALSO BE POSSIBLE LATE TONIGHT AND EARLY SUNDAY. MINOR ACCUMULATIONS
OF WINTER PRECIPITATION WILL BE POSSIBLE...MAINLY FOR ELEVATIONS ABOVE
2500 FEET. WIDESPREAD HAZARDOUS TRAVEL CONDITIONS ARE NOT EXPECTED
AT THIS TIME.
.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.
PATCHY FREEZING DRIZZLE WILL BE POSSIBLE EARLY SUNDAY...MAINLY AT
ELEVATIONS ABOVE 2500 FEET. WIDESPREAD HAZARDOUS TRAVEL CONDITIONS
ARE NOT EXPECTED AT THIS TIME. OTHERWISE...THE PROBABILITY OF
WIDESPREAD HAZARDOUS WEATHER DURING THIS PERIOD IS LOW AT THIS
TIME.
.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
$$
.
They wouldnt do it if it wasn't!
Dual Polarization
Q&As on Upgrade to
Dual Polarization Radar
The NHC is the National Weather Service.
Systems deemed tropical are covered by the NHC part of the weather service. When systems are deemed extratropical, they are handled by the HPC part of the weather service. The products issued for tropical systems differ from the products issued for non-tropical/extra-tropical systems, even if in some cases the impact is similar.
Warmer-than-average temperatures in much of Texas, northward through the Central and Northern Plains and westward across the Southwest, the Northern Rockies, and eastern Washington, Oregon and California, as well as the northern two-thirds of Alaska.
Cooler-than-average temperatures in Hawaii and in most of Florida, excluding the panhandle.
Drier-than-average conditions in Hawaii, the Pacific Northwest and Northern California, including Idaho, western Montana, and portions of Wyoming, Utah and most of Nevada.
Drier-than-average conditions in the upper Midwest, including Minnesota, Wisconsin, Iowa and northern Missouri and eastern parts of North and South Dakota, Nebraska, Kansas, and western Illinois.
Wetter-than-average conditions across the Gulf Coast states from the northern half of Florida to eastern Texas.
The rest of the country falls into the “equal chance” category, meaning these areas have an equal chance for above-, near-, or below-normal temperatures and/or precipitation.
This seasonal outlook does not project where and when snowstorms may hit or provide total seasonal snowfall accumulations. Snow forecasts are dependent upon the strength and track of winter storms, which are generally not predictable more than a week in advance.
NOAA's National Weather Service is the primary source of weather data, forecasts and warnings for the United States and its territories. NOAA’s National Weather Service operates the most advanced weather and flood warning and forecast system in the world, helping to protect lives and property and enhance the national economy. Working with partners, NOAA’s National Weather Service is building a Weather-Ready Nation to support community resilience in the face of increasing vulnerability to extreme weather. Visit us online at weather.gov and on Facebook.
NOAA’s mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. Visit us at www.noaa.gov and join us on Facebook, Twitter and our other social media channels.
Anyone found any sites that display the dual pol echos, other than paid sites?
sure it can it loves you
Nice video ...made me want to light my fireplace
The Hurricane Center chose not to issue any hurricane watches or warnings beyond North Carolina, even though many areas would see hurricane-force wind gusts. Instead, NHC allowed local NWS offices to issue an array of warnings ranging from high-wind warnings to coastal-flood warnings. Rick Knabb, the director of the NHC, told reporters that the decision was made in order to minimize confusion in the event that Sandy was reclassified as a post-tropical cyclone before making landfall, which would have required that all hurricane warnings be canceled, and other warnings to be issued instead.
“By using non-tropical warnings in these areas from the start, we avoid or minimize the significant confusion that could occur if the warning suite changed from tropical to non-tropical in the middle of the event,” NHC said in a statement.
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