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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Yes, it could indeed. A high that is offset from a surface low feature will impart shear to it. In fact, if you look at the shear tendency map for 90E you will see that only a very small area there is low shear and that shear has been rising generally in the vicinity.
That may be why 90E does not look as good now as it did a few hours ago, having lost direct overhead support from the high.
if you came back here after being banned 5 times than you have to expect abuse. please dont complain as you should be happy you are back.
Sad sad sad.
Absolutely! I think the comment here that it's an attempt to "sensationalize" in the interest of readership may be more accurate than the article itself...on the other hand, if you had asked me two months ago what I thought the odds of a huge company like BP pulling a bone-headed play like dumping tens of millions of gallons of oil into the GOM because they were trying to save a little money, I'd have said zero
Does this high moving have something to do with the swirl I mentioned off El Salvador creating some convection in that low shear? (again I'm probably totally off on this)
Another scenario with a probablity somewhere in the area of zero
I'm serious. I would join a JFV fan page.
In case you can't read the map well..
5%-10% chance of storms swirving east of Bermuda
20% chance of storms going up the East Coast
30% (possibly changing to a higher chance) of storms hitting Florida and the Gulf Coast do to strong highs
40% chance of storms entering the Caribbean, 10% of those staying south like Dean and Felix in 2007, 5% of storms getting into the Gulf but NOT hitting the USA, 25% of storms making a Gulf Coast landfall..
These numbers are based on recent seasons with Neutral conditions, La Nina conditions, warm sea temps, low shear values, and low pressures..
I'll have more in my report coming out possibly tomorrow, if I can get it done in time lol
Here's the map once again
DON'T TAKE IT SERIOUSLY!! It's only my first outlook for a potentially active and deadly season
Outlook map
img src="
You're so right, Flood. Nevertheless, it had been an exciting show last night (I didn't get much sleep). I hope so much, the top kill will work.
90L is back...
27/1745 UTC 30.8N 73.0W T1.0/1.0 90L
27/1145 UTC 30.6N 73.9W T1.0/1.0 90L
25/1145 UTC 30.0N 71.9W TOO WEAK 90L
No Prob....This current spill, now new undersea plumes, and, the pending season makes this disaster all the more critical as a learning tool as hurricanes become more intense in the coming years......I'm sure this particular problem, alone, will have the oil companies paying extra special attention to safety aspects if a storm threatens the Gulf this year.
90E AVN loop
Seriously.. are you JFV?
We're all hoping it works...thanks, barbamz!
he confirmed that he was Cybr much to my annoyance.
Eric, how many oilfields on dry land or at sea have caused the collapse of the surface or the seabed? Can you name me one full fledged collapse caused by the extraction of the oil? Further, are you under the impression that the oil deposit is drained?
LMAO!!!!! YES YOU ARE! you said it the other day!
Well, yeah...this process isn't like put a cork in a bottle...
They've been running models all day and continue to do so.
I don't see how the "lid" could collapse. Isn't the ocean floor where they drilled something like 11,000 feet thick before it gets to oil? I'd think that would be a pretty strong cap. What I'm puzzling about is what is creating the pressure causing the oil to erupt the way it is. Is it something like the weight of the earth and water above the oil being transferred into the oil (although fluid does not compress) but pressure nonetheless builds sufficiently to sent this column shooting up through the drilled hole at such a high pressure. Is it the pressure of the oil being lighter than water and creating pressure behind it as it rises in the column, or is it pressure that is created by the situation in the pool below that is released like gas from a newly opened can of carbonated beverage. Anybody know how to explain this?
the oil is under pressure am I right? so it won't collapse, just equalize pressure, then the flow will stop
Or try a lake-breeze along the shore line of one of the cooler Great Lakes, last week it was 93 degrees several miles inland but only 55 degrees in Superior and 46 degrees in Port Wing. Quite a shock driving through the temperature gradient!
One other thing...you are of course aware that this well was drilled in the Miocene fold zone, yes? An area with more or less cantilevered geology?
If it fails to reach 0 pressure the top kill failed. BP has stated the next step is to saw off the riser and install the top hat. The only problem with that is that if a hurricane comes the ship accepting oil will need to be detached from the production.
No matter what happens BP has a real mess on their hands. The casing program is such that if any leak develops in casing above the production casing it will again spill serious oil to the seabed. It's almost like they never even thought of P&A (plug and abandon) when they designed the casing.
This 90L looked like a classic subtropical depression if I've ever seen one. Is the NHC not ready?
Compare TS Gabrielle, 2007:
So, I hear that people are predicting an earthquake in the eastern part of the Hellenic plate, in eastern Grece or Western Turkey. And Katla may be close to erupting (how do you warn against an eruption?). If so (earthquake prediction is usually considered a pseudoscience, and an inexact one) I expect the quake to be M6.0 or higher: a M6.0+ has occured once every 24 hours for the past five days. Here is a list (Link):
May 23 - Central Peru, M6.1
May 24 - Acre, Brazil, M6.5
May 25 - Northern Mid-Atlantic Ridge, M6.3
May 26 - Southeast of the Ryukyu Islands, M6.4
May 27 - Vanuatu, M7.2
Here's a population exposure map of the most recent quake:
In other news...
the Alaotra Grebe is extinct.
Drug wars and protests in Jamaica kill 73. Link
thats a lot of words floodman, im but a simple salesman
Tropical Cyclone Advisory Number SEVEN
SUBTROPICAL DEPRESSION JOEL (16-20092010)
22:00 PM Réunion May 27 2010
========================================
At 18:00 PM UTC, Subtropical Depression Joel (1000 hPa) located at 26.4S 45.9E has 10 minute sustained winds of 50 knots with gusts of 70 knots. The subtropical system is reported as moving east southeast at 5 knots.
Forecast and Intensity
========================
12 HRS: 26.5S 45.9E - 40 knots (SUBTROPICAL)
24 HRS: 27.2S 46.1E - 30 knots (SUBTROPICAL)
Additional Information
=======================
Eye is still visible despite the west northwesterly vertical wind shear constraint. ECMWF model analysis strong westerly winds in the upper level only above the level 200 HPA and the wind shear constrain remains relatively weak below. This environment allows JOEL to resist better than previously forecasted despite an obvious tild between 37ghz and 89ghz on AQUA microwave imagery (2217z and 1024z). ECMWF and ALADIN numerical weather prediction models suggest that strongest winds should progressively extend towards the mid level on and after 0600z or 1200z and should therefore induce rapid weakening of the system. This forecast maintains therefore intensity strongest within the next 12 to 18 hrs than the previous one. Phase diagram don't suggest that this low has become tropical, Dvorak analysis is therefore not suitable for intensity estimation. 0640z ASCAT swath allows calibrating winds extension but not winds near the center. Pressure of the is high due to the small size of the system and high environmental pressures. JOEL is expected to keep on tracking slowly east southeast during the next 12 hours, under the steering influence of the mid level ridge located over northern part of Madagascar, then southesat as a ridge has rebuilt east of the system.
Yeppers......never had much of a chance that others was trying to give to begin with! OVER HYPE!
Sorry, went away for a bit. I cleaned up a few typos in my post as well. Need to slow down LOL.
The convection near El Salvador appears to be a part of 90E generally. It is not all that organized at this time
My thoughts exactly. I have been against drilling off Florida mainly because of a fear of so many tar balls it would drive the tourists away, one of our main economic engines. Never did I think something like this would happen. Guess I expected too much out of MMS.
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