NOAA predicts a near-normal Atlantic hurricane season

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

Share this Blog
33
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 629 - 579

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16Blog Index

629. Skyepony (Mod)
Quoting weatherbro:


Not one model brings it over central Florida.:)


Member Since: Posts: Comments:
Off for now.
Member Since: Posts: Comments:
627. j2008
Quoting KoritheMan:

I don't think most people understand the various Dvorak rules and constraints. It's why low-level cloud swirls devoid of convection are labeled tropical storms.

No offense, j.
Yea, dvorak is my weak point, I will eventually catch on.......
Member Since: Posts: Comments:
Sanvu
Member Since: Posts: Comments:
02E/MH/B/C3
RW FLAG ON
MARK
17.55N/105.5W
Member Since: Posts: Comments:
Member Since: Posts: Comments:

Quoting Skyepony:


It's a dvorak term..so why not adhere to dvorak rules??

There it is~ Flag thrown..They can take it back at some point if it warrents but for now EIR Rule 9 is in play..
I don't think most people understand the various Dvorak rules and constraints. It's why low-level cloud swirls devoid of convection are labeled tropical storms.

No offense, j.
Member Since: Posts: Comments:

Bud
Member Since: Posts: Comments:
Quoting KoritheMan:


We should just stick to "forecasting". It makes life easier. :)


lol
Member Since: May 26, 2007 Posts: 47 Comments: 1213
Quoting MississippiWx:


Considering the storm has yet to form and the models have been all over the place, I'm not really sure your local met needs to be in that area of profession. If he really made that claim already, then he is very uneducated. The odds of 94L becoming a strong and damaging storm are slim, but to say your area is out of the woods for a landfall, when some models bring it over you, is not wise. Just wait and see when/if 94L gets a name. The NHC will give you a better idea on track.


Not one model brings it over central Florida.:)
Member Since: May 26, 2007 Posts: 47 Comments: 1213
It's good to see some of the old timers back on the blog
Member Since: Posts: Comments:
Quoting weatherbro:


I pretty much agree though I'm afraid Florida casters won't.


We should just stick to "forecasting". It makes life easier. :)
Member Since: Posts: Comments:
Quoting wunderweatherman123:
the reason bud was upgraded to a cat 3 was that he was already a cat 3 hours ago before his EWRC should weaken to a 2 before landfall
Could always complete the EWRC before landfall.
Member Since: Posts: Comments:
615. Skyepony (Mod)
BUD on MIMIC. His eye has got tiny. If it was stacked perfect & cleared out we'd all be screaming pinhole.
Member Since: Posts: Comments:
the reason bud was upgraded to a cat 3 was that he was already a cat 3 hours ago before his EWRC should weaken to a 2 before landfall
Member Since: Posts: Comments:
Quoting Mamasteph:
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?


I pretty much agree though I'm afraid Florida casters won't.
Member Since: May 26, 2007 Posts: 47 Comments: 1213
things can sometimes happen in but a blink of an eye
Member Since: Posts: Comments:
I cant help but post this.
This is a Panavia Tornado.
Member Since: Posts: Comments:
610. Skyepony (Mod)
Fresh ASCAT 94L
Member Since: Posts: Comments:
609. j2008
Quoting KEEPEROFTHEGATE:
yes its on a downward turn now these east pacific storms can disappear fast watch and learn
I've watched my fair share of EPAC TC's, plus there is not any good reason why he should weaken. Still pleanty of warm water and time till landfall. If hes weakening I dont expect a whole lot besides what a little land interaction and EWRC can cause. But just in case I will get my crow ready haha..
Member Since: Posts: Comments:
608. Skyepony (Mod)
Quoting j2008:
I dont think so, looks like a EWRC nothing more. The fact that he strengthened to MH during an EWRC is pretty amazing.


It's a dvorak term..so why not adhere to dvorak rules??

There it is~ Flag thrown..They can take it back at some point if it warrents but for now EIR Rule 9 is in play..
Member Since: Posts: Comments:
There is really little Annular about Bud, just saying it doesn't fit the MO
Member Since: Posts: Comments:
0z GFS basically has the same track as the 0z NAM for 94L.
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
yes its on a downward turn now these east pacific storms can disappear fast watch and learn


Will be interesting to watch an annular hurricane do that.
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
yes its on a downward turn now these east pacific storms can disappear fast watch and learn
True but I agree with him its just an EWRC. But we will find out on the next microwave imagery pass.
Member Since: Posts: Comments:
Quoting j2008:
I dont think so, looks like a EWRC nothing more. The fact that he strengthened to MH during an EWRC is pretty amazing.
yes its on a downward turn now these east pacific storms can disappear fast watch and learn
Member Since: Posts: Comments:
602. Skyepony (Mod)
Quoting MississippiWx:


Considering the storm has yet to form and the models have been all over the place, I'm not really sure your local met needs to be in that area of profession. If he really made that claim already, then he is very uneducated. The odds of 94L becoming a strong and damaging storm are slim, but to say your area is out of the woods for a landfall, when some models bring it over you, is not wise. Just wait and see when/if 94L gets a name. The NHC will give you a better idea on track.


Should have seen them dance. I didn't see today, but yesterday they wouldn't show their model for Sun & Monday. It's all about the tourist, beach & making plans here for your Memorial Day weekend. ABC weather forecast for Orlando is owned by Disney..

Member Since: Posts: Comments:
POSS T.C.F.A.
94L/INV/XX
MARK
22.25N/79.50W
Member Since: Posts: Comments:
599. j2008
Quoting Skyepony:
Rapid Weakening Flag thrown on Bud..
I dont think so, looks like a EWRC nothing more. The fact that he strengthened to MH during an EWRC is pretty amazing.
Member Since: Posts: Comments:
Quoting KoritheMan:


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.
Quoting Hurricanes101:


meaning?
Lol I am not disagreeing with him. I was making a joke about how people always like to think a storm is annular when its not. So I said someone on the blog must be issuing NHC statements.
Edit: You guys should know better than to think I would say something like that. Or I hope you do.
Member Since: Posts: Comments:
Quoting Skyepony:
Rapid Weakening Flag thrown on Bud..
Cold waters nearer to the coast?
Member Since: August 3, 2005 Posts: 10 Comments: 5458
596. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #28
SEVERE TROPICAL STORM SANVU (T1202)
12:00 PM JST May 25 2012
=================================

SUBJECT: Category Two Typhoon In Sea South Of Japan

At 3:00 AM UTC, Severe Tropical Storm Sanvu (980 hPa) located at 22.7N 139.4E has 10 minute sustained winds of 55 knots with gusts of 80 knots. The cyclone is reported as moving north northeast at 7 knots.

Dvorak Intensity: T3.5

Storm Force Winds
=================
30 NM from the center

Gale Force Winds
================
170 NM from the center in northeastern quadrant
130 NM from the center in southwestern quadrant

Forecast and Intensity
=========================

24 HRS: 24.7N 141.8E - 60 knots (CAT 2/Severe Tropical Storm)
45 HRS: 26.5N 144.7E - 55 knots (CAT 2/Severe Tropical Storm)
69 HRS: 30.4N 149.6E - 45 knots (CAT 1/Tropical Storm)
Member Since: Posts: Comments:
580 KoritheMan: Beryl is a female name.

Roll out the Beryl,

577 GTcooliebai: ...the fact that this is coming during the Memorial holiday is going to spoil a lot of people's plans outdoor. Oh well, we need the rain, more important than a holiday.

We'll have a Beryl of fun...
Member Since: Posts: Comments:
02E/MH/B/C3
MARK
17.55N/105.5W
Member Since: Posts: Comments:
593. Skyepony (Mod)
Rapid Weakening Flag thrown on Bud..
Member Since: Posts: Comments:
Quoting Mamasteph:
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?


Considering the storm has yet to form and the models have been all over the place, I'm not really sure your local met needs to be in that area of profession. If he really made that claim already, then he is very uneducated. The odds of 94L becoming a strong and damaging storm are slim, but to say your area is out of the woods for a landfall, when some models bring it over you, is not wise. Just wait and see when/if 94L gets a name. The NHC will give you a better idea on track.
Member Since: Posts: Comments:
Quoting KoritheMan:
I was hoping 94L/Beryl would be my first chase opportunity. Unfortunately, looks like I'm working during the projected landfall time.

*sigh*



maybe we can get the NHC to push landfall back a bit
Member Since: April 26, 2006 Posts: 5 Comments: 3040
Quoting CosmicEvents:
If I was living in the Vero Beach, Fl. to Charleston, S.C. I'd have an eye on this "L". Especially in the mid zone, Between Savannah and Daytona, and extra-especially in the St. Simons to Flagler Beach zone. We're not talking a major hurricane here, mod-high TS likely, but intensity wise they say to prepare for 2 levels higher, just in case, and I'd be prepared to bring in possible flying objects and trim back trees and such at least and it's the perfect time to review your hurricane plans for all.




Done deal every year in the beginning of May..that way I can sit watch and wait..lol..Thanks guys..let you know how it goes here in Flagler County..
Member Since: Posts: Comments:
I was hoping 94L/Beryl would be my first chase opportunity. Unfortunately, looks like I'm working during the projected landfall time.

*sigh*
Member Since: Posts: Comments:
Member Since: Posts: Comments:
If I was living in the Vero Beach, Fl. to Charleston, S.C. area I'd have an eye on this "L". Especially in the mid zone, between Savannah and Daytona, and extra-especially in the St. Simons to Flagler Beach zone. We're not talking a major hurricane here, mod-high TS likely, but intensity wise they say to prepare for 2 levels higher, just in case, and I'd be prepared to bring in possible flying objects and trim back trees and such at least and it's the perfect time to review your hurricane plans for all.
Member Since: August 3, 2005 Posts: 10 Comments: 5458
Quoting Mamasteph:
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?


Most Models still show a Landfall around Jacksonville, some have shifted a little north into south Georgia, but not much has changed
Member Since: Posts: Comments:
**THE LATEST**
(click to enlarge; images can further be enlarged in Link window)


Member Since: June 29, 2009 Posts: 13 Comments: 5238
Hurricane Kenna

Link
Member Since: Posts: Comments:
582. Gorty
Quoting KoritheMan:


Her, dude. Her. Beryl is a female name.


Not yet. :p its still an "it" or I guess you can use any gender for invests.
Member Since: Posts: Comments:
Quoting Mamasteph:
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?


Right now I'd favor the north Florida/Georgia border. But things will probably change a bit as they always do.
Member Since: Posts: Comments:
Quoting Gorty:


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


Her, dude. Her. Beryl is a female name.
Member Since: Posts: Comments:
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
Member Since: Posts: Comments:

Viewing: 629 - 579

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16Blog Index

Top of Page

About JeffMasters

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