NOAA's forecast: a very active, possibly hyperactive Atlantic hurricane season
The National Oceanic and Atmospheric Administration (NOAA) issued its 2010 Atlantic hurricane season forecast today. NOAA forecasts a very active and possibly hyperactive season. They give an 85% chance of an above-normal season, a 10% chance of a near-normal season, and just a 5% chance of a below-normal season. NOAA predicts a 70% chance that there will be 14 - 23 named storms, 8 - 14 hurricanes, and 3 - 7 major hurricanes, with an Accumulated Cyclone Energy (ACE) in the 155% - 270% of normal range. If we take the midpoint of these numbers, NOAA is calling for 18.5 named storms, 11 hurricanes, 5 major hurricanes, and an ACE index 210% of normal. A season with an ACE index over 175% is considered "hyperactive." An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The forecasters note that in regards to the oil spill in the Gulf of Mexico,
"Historically, all above normal seasons have produced at least one named storm in the Gulf of Mexico, and 95% of those seasons have at least two named storms in the Gulf. Most of this activity (80%) occurs during August-October. However, 50% of above normal seasons have had at least one named storm in the region during June-July."
The forecasters cited the following main factors that will influence the coming season:
1) Expected above-average SSTs in the hurricane Main Development Region (MDR), from the Caribbean to the coast of Africa. SSTs in the MDR are currently at record levels, and the forecasters note that several climate models are predicting record or near-record SSTs during the peak portion of hurricane season (August - October.) "Two other instances of very warm SSTs have been observed in the MDR during February-April (1958 and 1969). In both years, the SST anomaly subsequently decreased by roughly 50% during the summer months. For 2010, although the record SST departures may well decrease somewhat, we still expect a continuation of above average SSTs throughout the Atlantic hurricane season. "
2) We are in an active period of hurricane activity that began in 1995, thanks to a natural decades-long cycle in hurricane activity called the Atlantic Multidecadal Oscillation (AMO). "During 1995-2009, some key aspects of the tropical multi-decadal signal within the MDR have included warmer than average SSTs, reduced vertical wind shear and weaker easterly trade winds, below-average sea-level pressure, and a configuration of the African easterly jet that is more conducive to hurricane development from tropical waves moving off the African coast. Many of these atmospheric features typically become evident during late April and May, as the atmosphere across the tropical Atlantic and Africa begins to transition into its summertime monsoon state."
3) There will either be La Niña or neutral conditions in the Equatorial Eastern Pacific. El Niño is gone, and it's demise will likely act to decrease wind shear over the tropical Atlantic, allowing more hurricanes to form. "La Niña contributes to reduced vertical wind shear over the western tropical Atlantic which, when combined with conditions associated with the ongoing high activity era and warm Atlantic SSTs, increases the probability of an exceptionally active Atlantic hurricane season (Bell and Chelliah 2006). NOAA's high-resolution CFS model indicates the development of La Niña-like circulation and precipitation anomalies during July."
How accurate are the NOAA seasonal hurricane forecasts?
A talk presented by NHC's Eric Blake at the 2010 29th Annual AMS Conference on Hurricanes and Tropical Meteorology studied the accuracy of NOAA's late May seasonal Atlantic hurricane forecasts, using the mid-point of the range given for the number of named storms, hurricanes, intense hurricanes, and ACE index. Over the past twelve years, a forecast made using climatology was in error, on average, by 3.6 named storms, 2.5 hurricanes, and 1.7 intense hurricanes. NOAA's May forecast was not significantly better than climatology for these quantities, with average errors of 3.5 named storms, 2.3 hurricanes, and 1.4 intense hurricanes. Only NOAA's May ACE forecast was significantly better than climatology, averaging 58 ACE units off, compared to the 74 for climatology. Using another way to measure skill, the Mean Squared Error, May NOAA forecasts for named storms, hurricanes, and intense hurricanes had a skill of between 5% and 21% over a climatology forecast (Figure 2). Not surprisingly, NOAA's August forecasts were much better than the May forecasts, and did significantly better than a climatology forecast.
Figure 1. Mean absolute error for the May and August NOAA seasonal hurricane forecasts (1999 - 2009 for May, 1998 - 2009 for August), and for forecasts made using climatology from the past five years. A forecast made using climatology was in error, on average, by 3.6 named storms, 2.5 hurricanes, and 1.7 intense hurricanes. NOAA's May forecast was not significantly better than climatology for these quantities, with average errors of 3.5 named storms, 2.3 hurricanes, and 1.4 intense hurricanes. Only NOAA's May ACE forecast was significantly better than climatology, averaging 58 ACE units off, compared to the 74 for climatology. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.
How do NOAA's seasonal hurricane forecasts compare to CSU and TSR?
Two other major seasonal hurricane forecasts will be released next week. On June 2, Phil Klotzbach and Bill Gray of Colorado State University (CSU) issue their forecast, and the British firm Tropical Storm Risk (TSR) will issue their outlook on June 4. A three-way comparison of the forecast accuracy of the three groups' forecast (Figure 2) reveals that all three organizations enjoy some success at making accurate seasonal forecasts, with NOAA and CSU making the best late May/early June forecasts overall. While the skill of these forecasts is low, they are useful for businesses such as the insurance industry.
Figure 2. Comparison of the percent improvement over climatology for May and August seasonal hurricane forecasts for the Atlantic from NOAA, CSU and TSR from 1999-2009 (May) and 1998-2009 (August). using the Mean Squared Error. Image credit: Verification of 12 years of NOAA seasonal hurricane forecasts, National Hurricane Center.
Central American disturbance
The Atlantic is currently quiet, with the non-tropical storm (90L) that we were watching now no longer a concern. There is an area of disturbed weather (90E) just off the Pacific coast of Mexico that will be a major concern for southern Mexico and much of Central America over the next 3 - 4 days. The disturbance will bring heavy rains to Central America during the remainder of the week, potentially bringing serious flooding rains to portions of Mexico, Guatemala, El Salvador, Honduras, and Nicaragua. NHC is giving the disturbance a high (>60% chance) of the disturbance developing into a tropical depression by Saturday. There is the potential for disturbed weather accompanying the disturbance--or the disturbance itself--to push into the Western Caribbean early next week and pose a threat to develop into a tropical depression. While there is high wind shear over the northern Caribbean, shear may be low enough to allow development should the disturbance stay in the southern reaches of the Caribbean. None of the models are currently calling for this to happen, and I think the threat is low. Any storm that develops in the Caribbean in the coming week would get steered to the northeast and will not pose a threat to the Gulf of Mexico. Wunderbloggers Weather456 and StormW have more on the tropics.
Figure 3. Visible satellite image of the Central American disturbance 90E this morning.
Oil threat for the coast of Louisiana to decrease this weekend
Light winds from the north or west are expected to prevail across the northern Gulf of Mexico through Friday, resulting in a lessened threat of oiling to the Louisiana shoreline, according to the latest trajectory forecasts from NOAA. However, the latest runs of the GFS model indicate a return to onshore winds out of the southwest for most of next week, which will likely bring oil back towards shore. At greatest risk will be the coast of Louisiana, and there will be heightened risk to Mississippi, Alabama, and the Florida Panhandle. I'll a have a more in-depth discussion of the oil spill forecast in Friday's blog.
Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA trajectory forecasts
Deepwater Horizon Unified Command web site
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Surface current forecasts from NOAA's HYCOM model
Synthetic Aperture Radar (SAR) imagery from the University of Miami
Join the Hurricane Haven with Dr. Jeff Masters: a new Internet radio show
Beginning next week, I'll be experimenting with a live 1-hour Internet radio show called "Hurricane Haven." The show will be aired at 4pm EDT on Tuesdays, with the first show June 1. Listeners will be able to call in and ask questions. Some topics I'll cover on the first show:
1) What's going on in the tropics right now
2) Preview of the coming hurricane season
3) How a hurricane might affect the oil spill
4) How the oil spill might affect a hurricane
5) New advancements in hurricane science presented at this month's AMS Conference on Hurricanes and Tropical Meteorology
6) Haiti's vulnerability to a hurricane this season
I hope you can tune in to the broadcast, which will be at http://www.wunderground.com/wxradio/wubroadcast.h tml. If not, the show will be recorded and stored as a podcast.
Jeff Masters
Reader Comments
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I know. That was my point.
Rodan now has winds to 135 MPH as It heads for the Loop current.
It works great because they are threatened by storms too, and they get some storm names native to their language.
You can find out yourself on satellite imagery when there is one threatening Miami. I can't tell you how big Igor is going to be, but it will be dang funny if he's a runt.
i agree. I was pointing out what you said nevermind
Here we go...
As big as RUSH's chair..in the EIB studio.
Dats a Cat 5 seat at least
LMFAO! how can anyone answer that!!!??
OK, Thanks Levi.
ROFL! Pat you crack me up.
http://www.nhc.noaa.gov/aboutnames_greek.shtml
he cant predict conditions this far out JFV, that is nearly impossible. The best guess is just that a guess.
around .6
Nobody knows, JFV. It depends on the individual system. If I knew the answer I would be a rich man!
Again, find out when a storm is threatening Miami. Conditions determining the size of a hurricane are short-term during the time of the storm, and are highly dependent on how large the initial disturbance was that spawned the storm in the first place. Thereafter the storm can go through a variety of changes along its journey.
I think you really do know quite well that nobody can answer that question accurately lol.
That sounds reasonable.
LoL :)
The answer is---
42!
FIU since Miami is one of the most hurricane prone areas in the US I promise you it will be hit by a hurricane soon. Miami is hit by a tropical storm almost every year.
A secondary name list (Item 4) was proposed at this years Region IV Hurricane Committee meeting, but was not accepted by the committee. They have not issued a report from the meeting yet, so don't know why they did not accept it.
It's going to be one of the most rapid reversals from El Nino to La Nina ever recorded.
huh?
Definitely
Office of the Federal Coordinator for Meteorology
The Office of the Federal Coordinator for Meteorological Services and Supporting Research,
...from the 64th Interdepartmental Hurricane Conference
March 1-4, 2010 -- in Savannah, Georgia.
http://www.ofcm.gov/ihc10/actionitems.pdf
Title
Replace Backup Tropical Cyclone “Greek Alphabet” Name List with Secondary
Atlantic Tropical Cyclone Name List
Submitter
NOAA/NWS
Discussion
Since 1953, NHC has utilized a naming protocol for Atlantic tropical cyclones that use
commonly known, short, distinctive names understood by the general public and media.
The name lists, which have been agreed upon at international meetings of the WMO,
have a French, Spanish, Dutch and English due to the geographical coverage of the
storms throughout the Atlantic and Caribbean.
If a name is retired, it can be easily replaced with another common name that is
understood and well known throughout the tropical basin.
However, if the primary name list is exhausted, as it was in 2005, NHC ceases the simple
and well understood naming protocol and resorts to use of the less understood and
inconsistent Greek Alphabet as the backup list. Feedback received from the general
public, media and EM community about the practice of using the Greek Alphabet for
naming tropical cyclones was generally unfavorable with comments such as “ludicrous,”
“idiotic” to “ridiculous.”
The use of the Greek Alphabet as a backup list to the primary list of Atlantic tropical
cyclone names has several disadvantages:
● Generally unknown and confusing to the public.
● Inconsistent with the standard naming convention used for tropical cyclones.
● If a Greek letter has to be retired, it cannot be replaced.
● Defeats the purpose of using commonly known, short distinctive names
understood by the public and media (ex: The Greek Alphabet jumps from a “B”
storm to a “G” storm then back to a “D” storm. If you expect an “F” storm
instead you will jump to “Z”).
Recommendation
Develop a secondary name list, utilizing conventions of the primary name list, that could
be placed into service if the primary Atlantic Cyclone name list is exhausted. Named
storms from the secondary or alternate list that require retirement could easily be
replenished based on recommendations from the WMO
(World Meteorological Organization - Official United Nations' authoritative voice on weather...)
IHC to forward to RA-IV Committee.
Action
Accept recommendation. Further action on this item is dependent on whether the RA-IV
Committee approves the recommendation.
Status
(3/22/10)
The WMO RA IV Hurricane Committee met from 8-12 March 2010 and did not approve
this recommendation.
CLOSED
From that document:
"The name lists, which have been agreed upon at international meetings of the WMO, have a French, Spanish, Dutch and English due to the geographical coverage of the storms throughout the Atlantic and Caribbean."
Apparently I was wrong, the name list purposely includes names from all 4 of those languages, as all of their countries are represented among the tropically threatened Caribbean islands. In that case there should definitely be no end to the name possibilities. The lists could go on forever....would be nice if they didn't repeat them so often unnecessarily. It would give specific storms so much more meaning to have a name all to their own for at least a couple decades.
How are the global SST's doin :) Plummeting?
when was the last Hurricane to Strike Miami?
When was wima?
04 ?
LOL
Wilma exhibited a very large 55 to 65 mile-wide eye while crossing the state, and the eye covered large portions of South Florida, including the eastern two-thirds of Collier County, extreme northwestern Miami-Dade County, the southern and eastern third of Hendry County, most of Broward County, and all of Palm Beach County. The eye also clipped the southeastern shore of Lake Okeechobee. The eye wall, the part of the storm with the strongest winds, affected virtually all of South Florida. Around 10:30 AM, a South Florida Water Management District (SFWMD) meteorological station located at the south end of Lake Okeechobee reported sustained winds of 103 mph. Sustained hurricane force winds (74 mph or greater) were observed over all areas except Hendry and Glades counties, and even those two counties measured hurricane force gusts. The highest recorded gusts were in the 100-120 mph range. An interesting and revealing aspect of Wilma was the wind field in the eye wall. The winds on the back (south/west) side of the eye wall were as strong, if not stronger, than those on the front (north/east) side. This goes against the common, but sometimes erroneous, belief that the strongest winds in a hurricane are always in the right-front quadrant of the storm. This occurred over much of South Florida, except for central and southern Miami-Dade County which barely missed the southwestern portion of the eye wall, and likely contributed to the heavier damage across Broward and Palm Beach counties compared to slightly lesser damage across much of Miami-Dade and Collier counties.
Wilma
LOL
Partly because the environmentalists have had their way and forced the rigs further and further offshore.
That storm actually proved out the new building codes. New construction was virtually unscathed, old construction, heavily damaged. Bolstered the new codes for sure.
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