NHC increases hurricane forecast lead times

By: Dr. Jeff Masters , 7:27 PM GMT on January 05, 2010

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The National Hurricane Center (NHC) announced today that beginning with the 2010 hurricane season, their hurricane and tropical storm watches and warnings for the U.S. coast will be extended in time by an additional 12 hours. Warnings will now be issued 36 hours in advance instead of 24 hours, and watches will be issued 48 hours in advance, instead of 36 hours. The increase in lead time for watches and warnings has been made possible by the tremendous improvement in hurricane track forecasts, which have improved by over 50% in the past twenty years (Figure 1). "With increases in population and infrastructure along vulnerable U.S. coastlines, emergency managers need more lead time in order to make life-saving decisions regarding evacuations", said Bill Read, director of NOAA's National Hurricane Center, in today's press release.


Figure 1. Average track errors for NHC Atlantic tropical storm and hurricane forecasts issued between 1990 - 2008. Track errors have improved by over 50% in the past 20 years. Image credit: National Hurricane Center.

Commentary
NHC has been debating for a number of years how best to "invest" the gains accrued from the steady improvement in hurricane track forecasts. One obvious savings from these better hurricane forecasts has come from the reduced evacuation costs. When a hurricane warning is issued 24 hours before the expected arrival of hurricane-force winds at the coast, it costs approximately $1 million to evacuate each mile of U.S. coast warned (Aberson et al., 2006). This number will be higher for more densely populated areas of the coast, such as Miami, and may be a factor of six lower for the North Carolina coast (Whitehead, 2003). According to a 2007 presentation at the 61st Interdepartmental Hurricane Conference, the length of coast warned decreased significantly in the past decade. During the decade of the 1990s, the average length of a hurricane warning was 455 miles, but that fell to just 335 miles between 2000 - 2006. Thus, an average of 120 fewer miles of coast were warned, at an average savings of $120 million per hurricane warning issuance. During this period, 17 storms requiring 25 hurricane warnings occurred. If the costs of coastal evacuations are indeed $1 million per mile, the improved hurricane forecasts between 2000 - 2006 resulted in savings of $3 billion compared to what the forecasts of the 1990s would have cost.

However, the new increased lead times for hurricane watches and warnings will lead to an increase in the length of coast warned, due to the higher uncertainties in hurricane tracks at longer forecast lead times. Between 2004 - 2008, approximately 25% of the coast that was placed under a hurricane warning actually received hurricane force winds; this percentage was 20% for areas placed under a hurricane watch. These percentages will decline with the new increased watch and warning lead times, costing money in unnecessary evacuations, and leading to increased complacency in the warned population due to too much "crying wolf".

Balanced against these increased costs is the potential disastrous loss of life should a hurricane hit an unprepared, heavily populated shoreline. With the U.S. population continuing to increase rapidly in coastal regions, the time needed to evacuate vulnerable populated regions is increasing. For example, evacuation times for the major urban areas of Texas are 28 - 34 hours for a major hurricane. Though the costs of overwarning the coast is significant, the savings in both human lives and dollars from increased warning times should outweigh these costs. In the 2002 book, Hurricane: Coping With Disaster, Dr. Hugh Willoughby, former director of the Hurricane Research Division of NOAA's Atlantic Oceanographic and Marine Laboratory, analyzed hurricane death statistics. In 1950, about 70 U.S. residents died per year in hurricanes. In the 50 years since, the coastal population expanded by a factor of 3.2, so if we were managing the hurricane problem the way we did in 1950, we would be losing about 220 people a year. The long-term average is still about twenty per year, not including the deaths due to the levee failures during Katrina. That means we're preventing about 200 deaths per year compared with 1950. How much are these saved lives worth? A life, is, of course, priceless, but in the cold world of economics, the value of life-saving scientific research and government regulations is estimated using statistics of what people are willing to pay to avoid certain risks, and what extra money employers pay their workers to take on additional risks. This data comes primarily from payroll statistics, but opinion surveys also play a role. In 2004, the Environmental Protection Agency (EPA) valued an American life at $8 million. EPA cut the value of a life by 8% that year, and a further 3% in May 2008, making the economic value of a life $6.9 million in today's dollars. The Department of Transportation gives a lower figure of a life as being worth $5.8 million. Using this number implies a savings of about $1.2 billion per year for the 200 lives saved per year by better hurricane warnings and evacuations. Today's decision by NHC to increase warning times should continue this trend of saving lives, which will also provide considerable monetary benefit. Despite the increased costs and dangers of "crying wolf" too often due to overwarning the coast, I believe that the double value of saving lives--for both the intrinsic and monetary value of a human life--makes NHC's move of increasing warning and watch times the right call.

References
Whitehead, J.C., 2003: "One million dollars per mile? The opportunity costs of Hurricane evacuation", Ocean and Coastal Management 46, 1069.

I'll have a new post on Thursday or Friday.

Jeff Masters

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289. jipmg
Quoting nrtiwlnvragn:


The airport is in the "Metropolitan" zone, and its reading is not much different from other areas in the same zone. Lower readings are seen in the "Inland" zone.

Link


is that why its showing mid and low 40s across most of those observations, while the airport is showing 49
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the WU forecast contest...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Bord, our airport is reporting 61 as of 9 p.m.

The thermometer I stuck outside 20 min ago says 62.... lol
Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting presslord:
OK...I asked Dr. Masters about a little 'side action' on the forecsst contest...and he didn't say 'no'...he actually didn't say 'yes' either...but I have found it's usually better to ask for forgiveness than permission...

so...I am going to pick someone to back in the contest...and commit to a $500 contribution to Portlight if they win...

so...if you are planning to participate in the contest...and want a shot at being the horse I back...shoot me a WU mail...

I will pick someone by placing all the names in a coffee mug and having my daughter draw one at random...


What contest are we talking about?
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Quoting KEEPEROFTHEGATE:
yeah iam in aussie my pick for the first day was 15/25/100


How are you even supposed to forecast the POP? Do you put either 0 or 100? I think I did an intermediate number similar to normal forecasts.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
offer void where prohibited by law...or otherwise frowned upon...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
umm...
Quoting Bordonaro:
271. The Atlantic Ocean, near Miami is probably near 75F. So, the temps will be milder than further inland.

It may be 50F at the Miami AP and 10 miles inland may be 42F. The Atlantic is like a huge radiator, especially if the winds are light.
you think soo or could the buildings have anything to do with it I once heard of the term "Urban Heat Island"
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting GTcooliebai:

honestly it's probably because the miami airport is near downtown which is near the beach.

Really, it is directly inland from Miami Beach by about 5 miles.
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Quoting TampaSpin:
Crazy as this would seem but, i wonder if the GOM could also produce snow bands like the ones seen from the Great Lakes if it was cold enough in Florida.

That would be interesting.. I would love to c sum snow.. but my chances r getting slim.. unless something happpens.. so what do u think? just freezing rain maybe sleet if that..
Member Since: August 15, 2008 Posts: 0 Comments: 2133
Quoting jipmg:
The airport is about 3-5 miles away from downtown

so its somewhat inland


The airport is in the "Metropolitan" zone, and its reading is not much different from other areas in the same zone. Lower readings are seen in the "Inland" zone.

Link
Member Since: Posts: Comments:
OK...I asked Dr. Masters about a little 'side action' on the forecsst contest...and he didn't say 'no'...he actually didn't say 'yes' either...but I have found it's usually better to ask for forgiveness than permission...

so...I am going to pick someone to back in the contest...and commit to a $500 contribution to Portlight if they win...

so...if you are planning to participate in the contest...and want a shot at being the horse I back...shoot me a WU mail...

I will pick someone by placing all the names in a coffee mug and having my daughter draw one at random...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting AstroHurricane001:
242, atmo: I already looked at your link for ENSO a few days ago, and noticed that instead of the Humboldt being cut off from the north, it was being cut off from the south. That does not indicate a normal El Nino.


I was getting an SST anomaly map, too.

This is all about 0.5 to 1.5 C SST anomalies? Hey, guy, our planet's fluids are constantly in a highly variable state.

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Quoting atmoaggie:
while the warmest part of the El Nino warm pool is still located in the Central Western Pacific

Last one: El Nino is not about the warmest SST location, it is about the warmest anomaly.

That said, the SSH anomaly (sea surface height compared to seasonal norms, another good measure) did have a classic Dec 1 look, but then had a higher area further west by Dec 18 (more indicative of a Modoki). What does this mean for the progression of this Nino? I dunno, but has happened before. Look through the records for previous events here: http://topex-www.jpl.nasa.gov/elnino/index.html
EDIT: OOPS, NO LINK!

(I wish the current ones were updated a little more timely)





If you look at SST anomalies, the warmest anomalies are along the Gulf Stream (as well as the coldest anomalies) and in the High Arctic. However, the warmest large anomaly is the one in the South Pacific. The SSH anomalies extending from the coast of Equador, by the way, are likely the result of subsurface warm areas, some as much as 7C warmer than normal, underneath the eastern equatorial Pacific emerging around late November.



Notice the warm ENSO pool funelling toward the southeast, toward Chile, and toward the south (into the South Pacific warm bulge).



Here are the subsurface temperature anomalies at the equator. Notice the warm anomaly drifting east and upward.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
271. The Atlantic Ocean, near Miami is probably near 75F. So, the temps will be milder than further inland.

It may be 50F at the Miami AP and 10 miles inland may be 42F. The Atlantic is like a huge radiator, especially if the winds are light.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Actually mara the GT in my name doesn't rep. Georgia Tech it stands for Georgetown and no not the Georgetown in DC, but Georgetown Guyana thus I'm Guyanese and Coolie stands for Indian and bai means boy.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Crazy as this would seem but, i wonder if the GOM could also produce snow bands like the ones seen from the Great Lakes if it was cold enough in Florida.
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Quoting KEEPEROFTHEGATE:
yeah iam in aussie my pick for the first day was 15/25/100

Is it open to people all over the world or just USA?
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Member Since: July 25, 2006 Posts: 0 Comments: 669
271. jipmg
The airport is about 3-5 miles away from downtown

so its somewhat inland
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Quoting BahaHurican:
Yeah that was the winter we slept in pajamas with feet (or socks), three blankets and a bedspread, and our folks had a space heater in their bedroom. [This was in Nassau.] Some people claim that it snowed in Grand Bahama, which is opposite Palm Beach county, but I think the official record shows hail. This current cold is about as close as we've gotten to that 1977 record stretch in the last 20+ years. It's hardly gotten below 60 here since 2000.


How chilly is it in Nassau right now?
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Seems like the same is often true here at NAS (MYNN). I wonder if it has anything to do with the pavement.... may also have to do with placement of equipment, which IIRC from a variety of discussions here, can influence reports.
Member Since: October 25, 2005 Posts: 19 Comments: 22735
Quoting presslord:


Can't they take a pill for that?!?!

*snicker, snicker*

Latency: Age of data
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COLD!!!!!!!
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Quoting jipmg:
Well if its jet fuel, then they shouldn't be using the air port for the official miami temperature..

honestly it's probably because the miami airport is near downtown which is near the beach.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting KEEPEROFTHEGATE:
atmo my more bigger concearn is what lies ahead as we get back into a more normal pattern and with start of severe season in the south pending the outcome of this cold air as it stands at the moment severe season may prove to be devastating for many


KOG i agree with you....this could really spell trouble for the upcoming severe weather spring.
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Thanks GTcollie. I hope GT wins being an FSU fan and alum. Just being from Miami and reading this blog and watching things the last few days, I see even the possibility of snow down here as so exciting. What atmospheric conditions ( what gods need to line up ) for it to happen with this coming front. Would it be wrap around flurries after the front passes or rain changing to snow type event. Did anyone notice how west palm beach airport reported snow this AM ? was that for real?
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242, atmo: I already looked at your link for ENSO a few days ago, and noticed that instead of the Humboldt being cut off from the north, it was being cut off from the south. That does not indicate a normal El Nino.

While I have not read the full contents of the link, I am aware that if the <20C zone in SSTs has shrunk to 1/5 of its original size (width) in five weeks, then that's an indication that the upwelling of the Humboldt is weakening, or the surface waters of El Nino are overpowering that of the Humboldt. What previous El Ninos have not done, is attack the Humboldt with warm water from the north, the east (Peru-Chile coast), the southwest (diagonal warm anomaly) and the northwest (equatorial El Nino). The cooling effect of the Humboldt no longer even really extends to the equator, as it usually does. Mostly the horizontal (latitude) cooling effect is staying at the latitude of central Peru. On the map you provided, the warm equatorial counter-current disrupts the weaker "Peruvian current" from the north, but this time, there is warmer water on the southern side of the South Pacific Gyre, cutting the Humboldt Current farther south than its usual highest concentration. By the way, I just notice: a tropical cyclone has popped up in the South Indian Ocean.

The fact that the warmest waters are not extending from the coast of Peru and Equador, but rather from the Central Pacific, extending farther east. The warm pool in the Southern Pacific is also abnormal, and this "bulge" in oceanic isotherms was created when Mick and other extratropical systems funelled warm ENSO water southward toward Antarctica. The cause of the warm water drifting from the Western Pacfic to the Eastern Pacific, by the way, was mainly Super Typhoon Nida. Being a Modiki El Nino, this pattern started from the west, not from the east. Ususually these types of El Ninos are supposed to be easier to predict, but the erratic nature of the storms co-interacting with SSTs has made this unpredictable. By the way, here are the current SST anomalies from NCEP:

Member Since: August 30, 2008 Posts: 8 Comments: 2835
Quoting AussieStorm:
Anyone here entering the WunderCast Competition
yeah iam in aussie my pick for the first day was 15/25/100
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atmo my more bigger concearn is what lies ahead as we get back into a more normal pattern and with start of severe season in the south pending the outcome of this cold air as it stands at the moment severe season may prove to be devastating for many
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You also have to remember MIA is very close to the Atlantic, and anything closer to the Gulf or Atlantic is going to have a slightly warmer temperature. The relatively warmer waters help moderate cold temps, especially close to the coast.
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Anyone here entering the WunderCast Competition
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32 on the outside and 70 on the inside. With the fire a blazing. I'm on the east coast not to far from the shuttle launch site.
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Quoting stormgazin:
How will the lack of QuikSCAT impact the NHC error trend?

I was thinking the same thing
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Quoting presslord:


Can't they take a pill for that?!?!
only you would say that
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255. jipmg
Well if its jet fuel, then they shouldn't be using the air port for the official miami temperature..
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Hey everyone. how are ya'll doing?
Member Since: August 15, 2008 Posts: 0 Comments: 2133
while the warmest part of the El Nino warm pool is still located in the Central Western Pacific

Last one: El Nino is not about the warmest SST location, it is about the warmest anomaly.

That said, the SSH anomaly (sea surface height compared to seasonal norms, another good measure) did have a classic Dec 1 look, but then had a higher area further west by Dec 18 (more indicative of a Modoki). What does this mean for the progression of this Nino? I dunno, but has happened before. Look through the records for previous events here: http://topex-www.jpl.nasa.gov/elnino/index.html
EDIT: OOPS, NO LINK!

(I wish the current ones were updated a little more timely)



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Quoting jipmg:
Weatherbug is reading low and mid 40s in all of miami dade, while the air port is reading 50.. why is the airport always warmer than most locations?


idk jet fuel?
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Quoting atmoaggie:
Oh, and WU's SST map is great for general temps for the whole globe in a little picture. Not very useful for any in-depth analysis.
Not to mention that it has latency issues, at times.


Can't they take a pill for that?!?!
Member Since: August 13, 2007 Posts: 0 Comments: 10492
How can it wind chill be warmer than the temp.
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Quoting mara0921:
In Oakland Park, FL, just west of I-95 about 1 miles south of KFXE. My little digital thermometor reads 44.3 degrees F @ 9:04 PM. Can anybody give us in broward a prognosis of any snow when the forecasted low moves our way thursday night. Also how low will it go tonight/tommorow night in broward?

Here ya go mara (additional links and info found on the bottom) based on temp. best chance of any winter precip. will be Sat. Night, who knows though these things change like wildfire



Link
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248. jipmg
Weatherbug is reading low and mid 40s in all of miami dade, while the air port is reading 50.. why is the airport always warmer than most locations?
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Quoting TampaSpin:


If the FT. Myers area is to get that cold....expect ours in Tampa/St.Pete to be at least 5degs colder.
From what I've seen over the past years, portions of NE Pinellas county freeze if downtown Tampa freezes.
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246. unf97
30.7 degrees currently.
Member Since: September 25, 2007 Posts: 0 Comments: 1193
Quoting mara0921:
In Oakland Park, FL, just west of I-95 about 1 miles south of KFXE. My little digital thermometor reads 44.3 degrees F @ 9:04 PM. Can anybody give us in broward a prognosis of any snow when the forecasted low moves our way thursday night. Also how low will it go tonight/tommorow night in broward?
Wow. 44 in Oakland Park! I dunno if they're still forecasting snow that far south, but definitely it's supposed to get to or near the freeze mark overnight, then up to the mid 50s tomorrow. Not so sure how cold things will get after Thursday.
Member Since: October 25, 2005 Posts: 19 Comments: 22735
Oh, and WU's SST map is great for general temps for the whole globe in a little picture. Not very useful for any in-depth analysis.
Not to mention that it has latency issues, at times.
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Link
cold here
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Quoting AstroHurricane001:


Usually, when you talk about climate change, you talk about changes occuring every year. This is changing every hour, as ocean current patterns shift and storms form that change the course of the currents. I've been trying to get this mentioned on Wikipedia for the past few days, but none of that is possible without a Reliable source, for example a publication (not raw data) by a university, or a peer-reviwed journal (unlikely considering the pace of this). What I need are third-party, primary or secondary sources that directly refer to the current situation regarding global weather patterns. What about the NWS? I've been monitoring the SSTs for a month now, and it does appear that global ocean currents are slowing down, but I still don't have the concrete evidence. That's why I also need to hear the skeptical arguments, then use that information to support these findings.

Also notice the "bulge" in warm temperatures about halfway between Chile and New Zealand. It points the eastern end of the ENSO warm pool directly towards Antarctica. Another smaller "finger" of warm water is from the temperature collision zone off South America pointing toward the northern end of the Antarctic Peninsula.


SST is not a good measure of Humbolt during Nino. I guess you did not see my posts from a few days ago?

A reposting:

And here is a detail of the Walker circulation and thermocline under normal conditions and with Nino.



A lot of excellent details here: http://www.sbg.ac.at/ipk/avstudio/pierofun/atmo/elnino.htm

Expected effects of an El Nino:

(Peruvian Current is synonymous with Humboldt Current)

And a part of the discussion (lots and lots more at the link):

The abnormally strong winds originating from the west push masses of warm surface water from the equatorial region against the South-American coast, and are ultimately deflected towards Mexico, Peru, and Ecuador, creating an area of warm water thousands of kilometers in length (fig.14). The mixed layers deepen, and the deeper cold waters are buried underneath. The sun warms the surface layer still further, thus enhancing the effect. The thermocline falls, and along with it the pool of nutrient rich water. In an immediate effect, this warm blob of water blocks off the upwelling of colder, nutrient rich water driving anchovies into starvation (fig.15). In addition to the torpedoed effect of the local fishing industry, these fish do no longer support large population of fish-feeding birds, whose droppings (guano) are mined for fertilizer. With the disappearance of anchovies and other marine organisms, predators like seabirds, further up the food-chain, experience a drastic decline in nutritonal resources. El Nino accounted for severe drops in the seabird populations in 1957 and 1965. In a long-lasting ENSO event, the dissolved seawater oxygen content becomes depleted.

Addendum: Note the "mixed layers deepen, and the deeper cold waters are buried underneath. The sun warms the surface layer still further, thus enhancing the effect." from above.

This effect is exactly what made us humans take note and name the El Nino long before we had any surface or satellite measurements.

And an example SST plot with Nino and without:
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Hmmm.... GTcooliebai's link is to an interesting summary of the 1977 winter weather that caused the snowfall outbreak in FL. It also mentions the 1983 cold spell, which I experienced first-hand as my coldest daytime temps to that point. I remember winters in the Bahamas when I was growing up as being much cooler on average than the ones we have been having of late....
Member Since: October 25, 2005 Posts: 19 Comments: 22735
In Oakland Park, FL, just west of I-95 about 1 miles south of KFXE. My little digital thermometor reads 44.3 degrees F @ 9:04 PM. Can anybody give us in broward a prognosis of any snow when the forecasted low moves our way thursday night. Also how low will it go tonight/tommorow night in broward?
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Anyways I have been in much colder weather, try Reading PA where one night got to 0. Oh and I could never forget the yr. me and the fam. went to spend xmas in Toronto when we woke up xmas morning there was white everywhere it had to be like a foot of snow. I even made a Snowman wish I had pics. to show u all.
Member Since: August 31, 2009 Posts: 0 Comments: 5628

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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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