Superstorm Sandy and the importance of polar orbiting satellites in forecasting

By: Dr. Jeff Masters , 8:19 PM GMT on January 03, 2013

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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

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283 FunnelVortex: Dumile is encountering wind shear, as you can see the upper levels are beginning to be blown off.

Also appears to be moving in the direction opposite of that predicted 24hours(or more)ago.
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Yaaaawwwwwwn.Another sorry January is shaping up.Nothing really happening around here.It appears we'll see more rain than snow this winter.Accuweather's forecast of "above normal snow" will blow again...
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..wonder if ft meyers is getting some rain?
Member Since: August 6, 2011 Posts: 4 Comments: 36998
GS do you think georgia and florida will get severe weather out of that?..looks mean huh
Member Since: August 6, 2011 Posts: 4 Comments: 36998
Trending stronger with this every run, trends a tad north and I could have some good severe wx if we can get some CAPE




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293. VR46L
Quoting FunnelVortex:
GFS shows a strong double barrel low in the north Atlantic at 100 hours.



Have to say there are lots of low pressure systems in the atlantic on that run ... but there is a favourable Jet stream forecast for once and It looks like I will get the most of a 2 week break from them
Member Since: March 1, 2012 Posts: 0 Comments: 6840
GFS shows a strong double barrel low in the north Atlantic at 100 hours.

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Here is JB's tweet about the artic air:

"@BigJoeBastardi: That is one heck of a cold ensemble run. This strat warm is like 1985. Inaug day that year... Super Bowl Sunday. 3 at DC.. at noon."
Member Since: April 29, 2009 Posts: 75 Comments: 14055
GFS shows a tropical storm or minor typhoon hitting northern Australia at 90 hours.

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Quoting 1900hurricane:

That is the 12Z GFS. The ECMWF doesn't release their precip forecasts (except under rare circumstances), but I would guess based on the output it does realease, the 12Z ECMWF would be even wetter than the GFS.





Texas says, "Bring that sh*t to me man!"
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213 Skyepony [quoting the AssociatedPress]: The Federal Emergency Management Agency warns that the National Flood Insurance Program will run out of money next week if Congress doesn't provide additional borrowing authority to pay out claims. Congress created the FEMA-run program in 1968 because few private insurers cover flood damage.

Which Congress should never have funded, which Congress should not fund now.
Government should not be in the business of encouraging banks&builders to place their customers in physical&financial danger.
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GFS is showing a possible typhoon/cyclone/hurricane near Austrailia at 372 hours.



Keep your eyes on this one, Aussie.
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Good Morning All .... 57.4 here this morning, low was 44.1 ... Forecast 67

I saw the video of Superman, that was from out here, Malibu I think he said.
Member Since: February 29, 2012 Posts: 0 Comments: 5690
Quoting bohonkweatherman:
Almost 1.5 inches of Snow 80 miles west of Austin, over 3 inches in El Paso and still snowing. Temp here is around 40.
Every little bits helps, of course, but much of the Central U.S. growing region needs many feet of snow to make up the precipitation shortfall, not mere inches. That, sadly, just doesn't seem likely--and the season of blistering, withering heat is less than five months away.

As more and more experts are starting to recognize, our climate appears to have turned a very ugly corner.
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Dumile is encountering wind shear, as you can see the upper levels are beginning to be blown off.

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Quoting bohonkweatherman:
I hope these models are correct. Winter rains are very important for Spring and Summer Crops. Less than 2 inches of rain here since Sept. 29th.

That is the 12Z GFS. The ECMWF doesn't release their precip forecasts (except under rare circumstances), but I would guess based on the output it does realease, the 12Z ECMWF would be even wetter than the GFS.



Member Since: August 2, 2006 Posts: 46 Comments: 11666
Almost 1.5 inches of Snow 80 miles west of Austin, over 3 inches in El Paso and still snowing. Temp here is around 40.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
Quoting 1900hurricane:

The Tuesday system at least looks promising at this point.



I hope these models are correct. Winter rains are very important for Spring and Summer Crops. Less than 2 inches of rain here since Sept. 29th.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
Quoting bohonkweatherman:
It isn't suppose to rain here until Tuesday? I am praying for a Decent rain. Happy receive anything but it would be nice to get everyone half an inch to 1 inch.

The Tuesday system at least looks promising at this point.



Member Since: August 2, 2006 Posts: 46 Comments: 11666
Quoting LargoFl:
Bohonk..check out your sunday rains..good huh..........
It isn't suppose to rain here until Tuesday? I am praying for a Decent rain. Happy receive anything but it would be nice to get everyone half an inch to 1 inch.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
Quoting LargoFl:
This is from Southeast Texas: A FEW LIGHT RETURNS
ARE SHOWING UP ON LOCAL RADARS. HOWEVER...EXTENSIVE DRY LAYER
STILL EXIST UP TO 7K FEET...SO THESE RETURNS WILL BE MAINLY VIRGA.

Showers off and on all night here and looked pretty good on radar but I dumped out like .001 to 002, most of it is Virga unfortunately.
Member Since: July 5, 2009 Posts: 0 Comments: 1348
SYNOPSIS FOR THE GULF OF MEXICO
1009 AM EST FRI JAN 4 2013

.SYNOPSIS...A COLD FRONTAL BOUNDARY HAS BECOME STATIONARY ACROSS
THE GULF...EXTENDING FROM NEAR FORT MYERS FLORIDA TO NEAR 22N93W
TO THE CENTRAL BAY OF CAMPECHE LATE THIS MORNING...WILL MEANDER
ACROSS THE GULF WATERS THROUGH SAT. ALTHOUGH N GALES HAVE ENDED
W OF THE BOUNDARY ACROSS THE SW GULF...HIGH SEAS WILL PERSIST
THROUGH THIS AFTERNOON THERE. A REINFORCING SURGE ON SUN WILL
PUSH THE FRONT INTO THE SE GULF WATERS BY EARLY MON WHERE IT WILL
STALL AND DISSIPATE. A THIRD COLD FRONT WILL MOVE OFF THE TEXAS
COAST ON TUE NIGHT.

$$
Member Since: August 6, 2011 Posts: 4 Comments: 36998
Member Since: August 6, 2011 Posts: 4 Comments: 36998
more floods coming here?................
Member Since: August 6, 2011 Posts: 4 Comments: 36998
well it IS January afterall..................
Member Since: August 6, 2011 Posts: 4 Comments: 36998
..yet more rain from another low tuesday for texas
Member Since: August 6, 2011 Posts: 4 Comments: 36998
HMMM NAM says no rain for me..oh well
Member Since: August 6, 2011 Posts: 4 Comments: 36998
Bohonk..check out your sunday rains..good huh..........
Member Since: August 6, 2011 Posts: 4 Comments: 36998
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I guess My real rain day is sunday
Member Since: August 6, 2011 Posts: 4 Comments: 36998
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Quoting 1900hurricane:
The 12Z GFS looks like it has reached a sort of compromise between its previous solutions and the ECMWF solutions.

wow that bottom right pic shows texas getting alot of rain, good for them if it pans out
Member Since: August 6, 2011 Posts: 4 Comments: 36998
TWC.... SUPERMAN SPOTTED...
LOL
click for TWC video
Member Since: April 23, 2011 Posts: 104 Comments: 14871
hi guys...it was a very cold morning here today,,,,18F
yesterday AM was....7F...felt like -1F...
Member Since: April 23, 2011 Posts: 104 Comments: 14871
Quoting FunnelVortex:
The GFS is showing a gigantic storm at 230 hours.


Nashville gets buried in this...
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The 12Z GFS looks like it has reached a sort of compromise between its previous solutions and the ECMWF solutions.

Member Since: August 2, 2006 Posts: 46 Comments: 11666
gee what a difference from behind the front and in front of it huh...
Member Since: August 6, 2011 Posts: 4 Comments: 36998
ST. PETERSBURG --
Bay area residents can expect clouds to hang around today, keeping temperatures cooler and some rain showers in the area.

According to Bay News 9 Meteorologist Juli Marquez, the cooler air will hang around today and tonight.
"The rain has been light this morning," Marquez said. "The front has moved south of here and has led to cooler temperatures."

Friday's early morning temperatures in the 50s will only rise into the mid 60s today.

Conditions will remain cloudy and cool with a 30 percent chance of rain. Friday night's low will dip back into the 50s and 40s in some parts of the area.
Member Since: August 6, 2011 Posts: 4 Comments: 36998
258. VR46L
Not the warmest predictions I have seen from the CPC 8-14 day outlook



and quite a bit of moisture too

Member Since: March 1, 2012 Posts: 0 Comments: 6840
When will the next forecasts for the 2013 season be issued? Earlier than April?
Member Since: October 29, 2012 Posts: 0 Comments: 55
Quoting pcola57:
Good Morning All,
A chilly 34 here with sun breaking through some wispy clouds aloft..
Gonna be a chilly one again..

Webcam from my area





That's impressive, considering there hasn't even been a cold front passage in a number of days. Your lows for the next week are expected to range from the upper 30s - mid 40s with highs in the upper 50s - lower 60s. The FL Panhandle really does have a (warm) temperate climate. Here in Orlando, it has been overcast for the last couple days with yesterday and today bringing a misty drizzle. I love this kind of weather, which is somewhat rare for my area (when temps are on the cooler side).
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lol!
Quoting hydrus:
G,nite Aussie..Feels funny saying good night when I just woke up .:)
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Quoting AussieStorm:

Much a do about nothing. Nothing about the Tornado outbreaks earlier this year??

Goodnight all
G,nite Aussie..Feels funny saying good night when I just woke up .:)
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Quoting SFLWeatherman:
My new 2012 Extreme Weather Events video!:)
Link

Much a do about nothing. Nothing about the Tornado outbreaks earlier this year??

Goodnight all
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My new 2012 Extreme Weather Events video!:)
Link
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Quoting Tazmanian:



56 is not cold if you want too no what cold is then i will show you what cold really is how about -100 be low 0 now thats cold

-100 what, °F or °C or °K or °R??

-100°F = -73.33°C or 199.82°K or 359.67°R
-100°C = -148°F or 173.15°K or 311.67°R
-100°K = -639.67°F or 373.15°C or -180°R
-100°R = -559.67°F or -328.71°C or -55.56°K

Which would you prefer?
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Quoting caneswatch:
I know this is not weather related but I'd like to share something:

Last month, I visited a gastrointestinal doctor, who had told me that my father had a gene called Lynch's Syndrome, which is the gene that gives you a 90% chance of acquiring colon cancer, my father had colon cancer last year, and survived, but unfortunately it took the life of my grandmother almost 11 years ago, who also had this gene.

They had me scheduled to undergo a colonoscopy and a genetic test to see if I had LS. I have a strong hunch that due to me being mostly made up of my mom's family genetics, I do not have LS, but I must get the test done.

Today, I underwent my first colonoscopy in nearly 6 years, and as soon as I woke up from my anesthetic state, the same doctor told me I didn't have any polyps in my colon. It's the first step of great news, but when I get my genetic test done in 2 1/2 weeks, I hope to receive more great news.

Congrats on having a clear test. I hope the same for the genetics test. I have a friend who went in for a colonoscopy and ended up with a 50/50 survival chance. Needless to say, they found colon cancer. I have not spoken to her in a while but heard through the coconut telegraph that she was ill and is doing better, so I do not know what symptoms, if any, she had prior to the test.
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Quoting TampaBayStormChaser:
BRRRR...cold outside...56 Degrees and Cloudy with a breeze. No sun, making it feel cold.



56 is not cold if you want too no what cold is then i will show you what cold really is how about -100 be low 0 now thats cold
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248. VR46L
Quoting Minnemike:





wow

look at all the


space i can take up


guys





??????

Anyways predicted GFS rainfall for next 24hrs

Member Since: March 1, 2012 Posts: 0 Comments: 6840

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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