NOAA predicts a near-normal Atlantic hurricane season

By: Dr. Jeff Masters , 9:17 PM GMT on May 24, 2012

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NOAA forecasts a near-normal Atlantic hurricane season in 2012, in their May 24 outlook. They give a 50% chance of a near-normal season, a 25% chance of an above-normal season, and a 25% chance of a below-normal season. They predict a 70% chance that there will be 9 - 15 named storms, 4 - 8 hurricanes, and 1 - 3 major hurricanes, with an Accumulated Cyclone Energy (ACE) 65% - 140% of the median. If we take the midpoint of these numbers, NOAA is calling for 12 named storms, 6 hurricanes, 2 major hurricanes, and an ACE index 102% of normal. This is very close to the 1981 - 2010 average of 12 named storms, 6 hurricanes, and 3 major hurricanes. Hurricane seasons during the active hurricane period 1995 - 2011 have averaged 15 named storms, 8 hurricanes, and 4 major hurricanes, with an ACE index 153% of the median. Only five seasons since 1995 have not been above normal--including four El Niño years (1997, 2002, 2006, and 2009), and the neutral 2007 season.


Figure 1. The strongest Atlantic hurricane of 2011, Ophelia, as seen at 1:40 pm EDT October 1, 2011. At the time, Ophelia was a Category 3 hurricane with 120 mph winds. At 11 pm that night, Ophelia peaked at Category 4 strength with 140 mph winds. Image credit: NASA.

The forecasters cited the following main factors that will influence the coming season:

1) Near-average sea surface temperatures (SSTs) are expected in the hurricane Main Development Region (MDR), from the Caribbean to the coast of Africa between between 10°N and 20°N. SSTs in the MDR during April were near-average, and are expected to remain so during hurricane season, based on current observations, climatology, and long-range model forecasts.

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 1995-2010, some key aspects of the tropical multi-decadal signal within the MDR have included reduced vertical wind shear and weaker easterly trade winds, below-average sea-level pressure, a configuration of the African easterly jet that is more conducive to hurricane development from tropical cloud systems (aka Easterly waves) moving off the African coast, and warmer than average SSTs."

3) An El Niño event may occur this year: "Another climate factor known to significantly impact Atlantic hurricane activity is the El Niño-Southern Oscillation (ENSO.) The three phases of ENSO are El Niño, La Niña, and ENSO-Neutral. El Niño events tend to suppress Atlantic hurricane activity, while La Niña events tend to enhance it (Gray 1984). If El Niño fails to develop, the probability of an above-normal Atlantic hurricane season will be higher and the actual seasonal activity will likely be toward the upper end of our predicted ranges." There is currently of lot of uncertainty whether or not an El Niño event will develop in time for the August - September - October peak of hurricane season--the latest NOAA El Niño discussion is giving a 41% chance of an El Niño event during hurricane season, and a 48% chance of neutral conditions.

4) NOAA is increasingly using output from ultra-long range runs of the computer forecast models we rely on to make day-to-day weather forecasts, for their seasonal hurricane forecasts: "The outlook also takes into account dynamical model predictions from the NOAA Climate Forecast System (CFS), the European Centre for Medium Range Weather Forecasting (ECMWF), the United Kingdom Meteorology (UKMET) office, and the EUROpean Seasonal to Inter-annual Prediction (EUROSIP) ensemble. These models show large spreads in the ENSO forecasts for ASO, ranging from ENSO-Neutral to a moderate-strength El Niño episode. As a result, their forecasts for the Atlantic hurricane season also show a considerable spread, ranging from slightly above normal to slightly below normal."

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. Not surprisingly, NOAA's August forecasts were much better than the May forecasts, and did significantly better than a climatology forecast.


Figure 2. 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.

I'll have an update on Hurricane Bud and Invest 94L Friday morning.

Jeff Masters

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579. Gorty
Link

Oh gosh, I hope that is not the start of an outer band for its western side. Its the northwestern part of the storm
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578. Skyepony (Mod)
Windsat of 94L..
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Quoting BrickellBreeze:
Tropical Cyclones hardly ever hit the Coastline from Savannah, Ga to North of St.Augustine,FL.

What a Rare track.
That would be an anomaly track and the fact that this is coming during the Memorial holiday is going to spoil a lot of peoples plans outdoor. Oh well we need the rain more important than a holiday.
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Local met. stated tonight on local news for central Florida that track for 94L has shifted more easternly and North Fla was out of woods for the most severity of the storm..Georgia will take the brunt of it....Any comments?
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575. Gorty
Quoting KoritheMan:


Yes.


I am scared to know what it will do once the shear relaxes since with the shear it is slowly getting better. Luckily we will still have dry air but right now dont really think the dry air is affecting him too much aside from a dry western half
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Quoting KoritheMan:


Linda never hit Mexico:



Ooops... I get her confused with Kenna. I meant Kenna haha, from 2002.
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Quoting Gorty:
Looks like 94l is getting better around his center. Am I right?


Yes.
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Quoting MississippiWx:
Bud looks like he is about to or is going through an eye wall replacement cycle. If he does that, it's probably downhill for him due to the dry air to his west.


A 2200Z SSMIS overpass depicted a large outer band in the western semicircle, which could presage an eyewall replacement cycle.
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571. Gorty
Looks like 94l is getting better around his center. Am I right?
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Tropical Cyclones hardly ever hit the Coastline from Savannah, Ga to North of St.Augustine,FL.

What a Rare track.
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Quoting LostTomorrows:


Maybe Linda? She was a buzzsaw of a category 5.


Linda never hit Mexico:

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Derived from (NHC) ATCF data for HurricaneBud for 25May12amGMT:
24May6pmGMT's MaximumSustainedWinds and MinimumPressure have been re-evaluated&altered
from ~100knots(69mph)111k/h and 961millibars to ~95knots(109mph)176k/h and 962millibars
Its most recent (25May12amGMT) position was 16.8n106.1w
Its vector had changed from NEast at ~11.3mph(18.2k/h) to NNEast at ~10.1mph(16.3k/h)
MaxSusWinds had increased from ~95knots(109mph)176k/h to ~100knots(115)185k/h
And minimum pressure had decreased from 962millibars to 960millibars

For those who like to visually track H.Bud's path...
PVR is PuertoVallarta . ZLO is Manzanillo . LZC is LazaroCardenas

The southwesternmost dot is where TropicalStormBud became HurricaneBud
The southwesternmost dot on the longest line-segment was H.Bud's most recent position

The longest line-segment is a straightline-projection through H.Bud's 2 most recent positions
to the coastline
The unconnected coastline dot was the endpoint* of the 24May12pmGMT straightline*projection
The ZLO dumbbell was the endpoint of the 24May6pmGMT straightline projection
On 25May12amGMT, H.Bud was headed toward passing over BahiaTenacatita in ~15hours from now

Copy&paste pvr, zlo-18.982n104.21w, 18.78n103.84w, lzc, 14.0n107.7w-14.6n107.5w, 14.6n107.5w-15.2n107.1w, 15.2n107.1w-16.0n106.5w, 16.0n106.5w-16.8n106.1w, 16.0n106.5w-19.307n104.823w into the GreatCircleMapper for more^information
The previous mapping for comparison.

* 15.3n106.9w was re-evaluated&altered to 15.2n107.1w. So an incorrect vector(direction&speed) was calculated for 24May12pmGMT from using the original incorrect position.
That incorrect vector produced an incorrect straightline projection leading to an incorrect endpoint.
Nonetheless I am reposting it to maintain historicity with the 2 previous maps.
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Quoting hurricanehunter27:
Apparently someone on the blog issues NHC statements.


We are allowed to disagree. For example, my forecasts are not constructed by paraphrasing the professionals. They are what I come up with using the data available to me. Sometimes they're right, other times they're not (like yesterday when I said no development from 94L). That's the name of the game, and the beauty of free speech. Besides, we're allowed to be a little more flexible when we aren't affiliated with government agencies.
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Quoting Walshy:
When was the last time Mexico was hit by an annular hurricane?


Maybe Linda? She was a buzzsaw of a category 5.
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Quoting Skyepony:


Embeded Center.

It could clear soon but not a typical eye scene of an annular.


Ewrc
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Quoting MississippiWx:
Bud looks like he is about to or is going through an eye wall replacement cycle. If he does that, it's probably downhill for him due to the dry air to his west.


It's already in one
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When was the last time Mexico was hit by an annular hurricane?
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Bud looks like he is about to or is going through an eye wall replacement cycle. If he does that, it's probably downhill for him due to the dry air to his west.
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Quoting hurricanehunter27:
Apparently someone on the blog issues NHC statements.


meaning?
Member Since: March 10, 2010 Posts: 1 Comments: 7530
that image certainly didnt look annular
Member Since: April 26, 2006 Posts: 5 Comments: 3098
Quoting HurricaneDean07:

He maybe a friend to us, but not to Mexico.


Yeah, obviously he is a amigo.
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Quoting Hurricanes101:


so the NHC says its Annular, but the test does not?
Apparently someone on the blog issues NHC statements.
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Quoting BrickellBreeze:


Image not showing......




i can see that any way i post the link



Link
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Quoting trHUrrIXC5MMX:
ANNULAR HURRICANE

Not even close.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
555. Skyepony (Mod)
Quoting weatherh98:


What next, a pinhole?


Embeded Center.

It could clear soon but not a typical eye scene of an annular.
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Quoting K8eCane:
But am i correct that annulars dont have long life spans?
Quoting K8eCane:
But am i correct that annulars dont have long life spans?
Annular hurricanes can support wind shear dry air and Cold waters but I do not know of mountainous terrains like Mexico.
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Quoting bluenosedave:


Well, he's certainly not Bud Lite anymore.

He maybe a friend to us, but not to Mexico.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting Tazmanian:
for 94L




Image not showing......
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...this doesn't look like an annular hurricane at all.
Member Since: July 7, 2010 Posts: 0 Comments: 5672
Quoting KoritheMan:
I just wrote a blog on 94L and Bud.

I'll still be hanging around for a while longer.

I almost forgot it is May 24 as opposed to June 24. With this relatively active look to the Atlantic Basin, one would think it is late June/early July. If this keeps up, it would not surprise me if sometime in June we end up with our first Atlantic hurricane.
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for 94L


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Quoting K8eCane:



you mean they stay annular longer than if they were not annular?


I mean they have generally higher lifespans, and are also usually stronger.
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Quoting stormpetrol:

Its ok don't worry about it, I don't hold malice at all, but when it was in this area and even had a LLC off and on all you you could hear about was the shear, now that is it moved away and shear is even worse there is 60% of development and I don't doubt that it probably will develop, but it was practically ignored until it began to move further north, like I said before just saying.... I could be totally wrong and accept that!

The reasons for increasing chences of development were due to the formation time frame coming closer into view, and is seeming to be more likely. only about 10% of the reasons for increasing the chances were becuase of location.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Apologies for the double post.

Anyway, not sure why the NHC discussion called it annular. Just like Skye posted, the test came back with a zero...not even marginal.
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Quoting bluenosedave:


Well, he's certainly not Bud Lite anymore.


XD
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I hate to go to Wiki when we have Kori but he cant spoon feed us
Member Since: April 26, 2006 Posts: 5 Comments: 3098
Good evening... I see we are at 60% now.
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There is nothing annular about Hurricane Bud.
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Quoting MississippiWx:
There is nothing annular about Hurricane Bud.


agreed
Member Since: March 10, 2010 Posts: 1 Comments: 7530
Edit.
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Quoting Skyepony:
## ANNULAR HURRICANE INDEX (AHI) EP022012 BUD 05/24/12 18 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=6 NFAIL=1 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##


so the NHC says its Annular, but the test does not?
Member Since: March 10, 2010 Posts: 1 Comments: 7530
Quoting trHUrrIXC5MMX:
ANNULAR HURRICANE


This is not good. Those people in the path are in for a very hard time. I'm glad I can spare some cash to help out.
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Quoting MississippiWx:
0z NAM is sticking with its previous solution of bringing 94L (Berryl) onshore around Jacksonville, taking it across the state into the extreme Northern Gulf.

Surface Map at 72hrs:



The 500mb map shows why the NAM predicts this. The 500mb ridge over the Mid-South gets squeezed and pushed to the north of 94L as a trough approaches from the West and 94L's low pressure invades from the southeast. 94L is then forced to go west on the southern periphery of the ridge.



The Track seems consistent (NE FL, SE GA), Now the question is how strong will it become..
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536. Skyepony (Mod)
## ANNULAR HURRICANE INDEX (AHI) EP022012 BUD 05/24/12 18 UTC ##
## STORM NOT ANNULAR, SCREENING STEP FAILED, NPASS=6 NFAIL=1 ##
## AHI= 0 (AHI OF 100 IS BEST FIT TO ANN. STRUC., 1 IS MARGINAL, 0 IS NOT ANNULAR) ##
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Quoting K8eCane:
But am i correct that annulars dont have long life spans?


Opposite I think
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Quoting KoritheMan:


It's the opposite, actually.



you mean they stay annular longer than if they were not annular?
Member Since: April 26, 2006 Posts: 5 Comments: 3098
I just wrote a blog on 94L and Bud.

I'll still be hanging around for a while longer.
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Quoting K8eCane:
But am i correct that annulars dont have long life spans?


It's the opposite, actually.
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Quoting stormpetrol:

Cosmic, trust you are doing well, as usual you make me laugh!
A little laughter isn't the worst thing in the world. It's healthy. I'm well enough health wise. I hope the same for you my friend. We've been through a few seasons together on this blog and managed to make it through. Let's do it again!
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But am i correct that annulars dont have long life spans?
Member Since: April 26, 2006 Posts: 5 Comments: 3098
All I read was Major Hurricane.... Annular....
Member Since: September 3, 2011 Posts: 13 Comments: 3470

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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.