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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Quoting MAweatherboy1:
Confirmed tornado on the ground in central Wisconsin... The storm has good rotation, luckily the tornado is over mostly rural areas.


What radar you using to view that, what location.
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On his webcast, one of our local TV meteorologists dismissed the amplitude of the gfs trough and said the NW flow from the ECMWF with a weak trough is more likely due to climatology and cold air not dipping very far down into the US in early June.

the SE Us could see rain.
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Quoting AtHomeInTX:


Not sure how many rode up and down y'all's coast. Apparently it's rare for a storm to form off the Carolina's to cross Florida and survive in the gulf. Disclaimer: the 34 storm the only storm to cross Florida and make landfall in TX. I know I said that before but it still amazes me. :)

July 24-26th, 1934: The third storm of the season formed off the North Carolina coast on the 21st. It then moved south and southwest across Florida into the eastern Gulf...a move only one
other cyclone on record has ever matched.
It then developed rapidly south of Louisiana on the
24th and struck just north of Corpus Christi (Rockport) on the 25th as a minimal hurricane. Winds
at Corpus Christi gusted to 56 mph as the pressure fell to 29.12". Rockport saw a pressure of
28.79". Twenty-four hour rainfall records were set for July at Falfurrias (4.52" on the 26th) and Fowlerton (4.75" on the 24th) St. Joseph’s Island had a 10.2 foot storm surge. Damage estimates were near $4.5 million, mostly to crops. Nineteen died in Texas due to the storm.





The latter "Hurricane 2" was responsible for the greatest flood in South Louisiana history. My town of Crowley, Louisiana received 33" of rain in a 2 day period
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alright guys this is what's gonna happen based on the NHC map


FORECAST POSITIONS AND MAX WINDS

INIT 24/2100Z 16.4N 106.4W 95 KT 110 MPH
12H 25/0600Z 17.4N 105.9W 100 KT 115 MPH
24H 25/1800Z 18.6N 105.4W 85 KT 100 MPH
36H 27/1800Z 19.5N 105.5W 30 KT 35 MPH...OVER WATER
48H 28/1800Z 19.0N 105.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
72H 26/0600Z 19.8N 105.2W 65 KT 75 MPH...INLAND
96H 26/1800Z 20.5N 105.1W 45 KT 50 MPH...INLAND


LOL!!!
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Confirmed tornado on the ground in central Wisconsin... The storm has good rotation, luckily the tornado is over mostly rural areas.
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Quoting LargoFl:

Convection Blowing up closer toward the center now.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting tampahurricane:
I made it through the storm in St. petersburg, im sure you will also. lol
glad your safe
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I made it through the storm in St. petersburg, im sure you will also. lol
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crap!
The eye is contracting...
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Quoting trHUrrIXC5MMX:
\

didn't happen....

Nope. It's really close though.
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Finally, its raining and booming and getting real windy now,dont like that RED on the radar coming towards me lol, but we need this rain real badly
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Quoting GeorgiaStormz:
One of our local news station's models showed Alberto hitting the South GA coast with a well defined eye region and spiral bands.
That would have to be a 50-60 mph tropical storm, so that probably will not happen :/

You mean Beryl?
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting TropicalAnalystwx13:
Deep convection is building around the eye again rapidly.

It's definitely possible to see Major Hurricane Bud at 8PM.

\

didn't happen....
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One of our local news station's models showed Beryl hitting the South GA coast with a well defined eye region and spiral bands.
That would have to be a 50-60 mph tropical storm, so that probably will not happen :/
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Dinner time now but will check in later.
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Quoting tampahurricane:
St. Petersburg got slammed, went out chasing water in business on US19 got between 3-5 inches within less than an hour. There was a 100% chance of hail, i witnessed a little hail on the road but i mostly missed the hail core. Starting to slowdown now.
gee its amazing, they are getting hammered..look............
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Quoting stormpetrol:

Thanks, this year is bit unusual already :), now the sky is a funny light yellow, I guess a reflection the sun trying to break through rain clouds!


Yeah, weird colour outside. See my edit to the post where I inserted the Twave info. They have it just east of the islands but position stated to be unsure. Given that position it would seem the timing would put it here early next week as progged by the GFS
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Quoting K8eCane:


I hope mexico doesnt have a bunch of mudslides because of Bud. Storms can really devastate them down there.
one good thing, i read all or most of mexico's oil rigs are on the Atlantic side..it sure looks like Bud wants to avoid the mountains..so far anyway
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A lot of stuff happening out there...
Member Since: July 7, 2010 Posts: 0 Comments: 5725
Quoting kmanislander:


The models have been hinting at a low developing in this area around mid week next week. I do not know the forward spped of the wave but they sometimes provide the spark needed for something to spin up. Usually the waves are pretty subdued in the Eastern Caribbean, especially this early in the year.

The GFS tracks the wave to our area quite nicely but does not do much with it except more rain. The 18UTC run shows good rotation with the wave all the way into the NW Caribbean. Just have to watch it.

Thanks, this year is bit unusual already :), now the sky is a funny light yellow, I guess a reflection the sun trying to break through rain clouds!
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Quoting LargoFl:


I hope mexico doesnt have a bunch of mudslides because of Bud. Storms can really devastate them down there.
Member Since: April 26, 2006 Posts: 5 Comments: 3222
St. Petersburg got slammed, went out chasing water in business on US19 got between 3-5 inches within less than an hour. There was a 100% chance of hail, i witnessed a little hail on the road but i mostly missed the hail core. Starting to slowdown now.
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Quoting K8eCane:



I have to say that i do hope this storm forms because i am anxious to see just what it will do! And i also know it is NOT forecast to become a hurricane, is it?
dont think so, one weather guy said a subtropical or tropical storm at best
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Quoting stormpetrol:

:) True,if the shear had been this low 2 days ago we might have had a TS on our hands, I noticed a wave just entered the Eastern Caribbean with low shear ahead, only inhibitor sames be dry air atm, what's your thoughts?


The models have been hinting at a low developing in this area around mid week next week. I do not know the forward speed of the wave but they sometimes provide the spark needed for something to spin up. Usually the waves are pretty subdued in the Eastern Caribbean, especially this early in the year.

The GFS tracks the wave to our area quite nicely but does not do much with it except more rain. The 18UTC run shows good rotation with the wave all the way into the NW Caribbean. Just have to watch it.

EDIT

From the discussion

A tropical wave extends from 12n57w to 8n60w moving W near 15
kt. The wave lies embedded within a broad area of enhanced
moisture present in total precipitable water imagery. Due to
interaction with an upper level trough earlier in the week...the
exact location of the wave has been difficult to discern.
Scattered moderate convection is E of the axis from 9n-11n
between 56w-59w...and W of the wave axis from 12n-15n between
60w-66w.
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Quoting LargoFl:
lol it sure is strange this storm



I have to say that i do hope this storm forms because i am anxious to see just what it will do! And i also know it is NOT forecast to become a hurricane, is it?
Member Since: April 26, 2006 Posts: 5 Comments: 3222
BULLETIN
HURRICANE BUD INTERMEDIATE ADVISORY NUMBER 16A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP022012
500 PM PDT THU MAY 24 2012

...BUD REMAINS JUST BELOW MAJOR HURRICANE STRENGTH...

SUMMARY OF 500 PM PDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...16.7N 106.2W
ABOUT 200 MI...325 KM SSW OF MANZANILLO MEXICO
ABOUT 260 MI...420 KM S OF CABO CORRIENTES MEXICO
MAXIMUM SUSTAINED WINDS...110 MPH...175 KM/H
PRESENT MOVEMENT...NE OR 35 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...962 MB...28.41 INCHES
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Quoting K8eCane:
No one may believe this, but my friend wanted rain on her yard and garden sooooo bad, and we stood in her yard and watched the rain stop at the stop sign about 50 feet from her house
lol it sure is strange this storm
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Quoting GTcooliebai:
This storm is such a tease. I know folks in Safety Harbor and St. Petersburg are probably getting flooding, yet in Largo not a single drop.



lol all day I have been praying for rain, and look at what its doing hahaha..gee i just cant win for trying
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No one may believe this, but my friend wanted rain on her yard and garden sooooo bad, and we stood in her yard and watched the rain stop at the stop sign about 50 feet from her house
Member Since: April 26, 2006 Posts: 5 Comments: 3222
**THE LATEST**
(click to enlarge; all graphics can be further enlarged


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Quoting GeorgiaStormz:
The ECMWF idea of Beryl:

That would be interesting...
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Quoting kmanislander:


94L taking one last crack at us :-)

Actually a rather small cloud but intense it seems

:) True,if the shear had been this low 2 days ago we might have had a TS on our hands, I noticed a wave just entered the Eastern Caribbean with low shear ahead, only inhibitor sames be dry air atm, what's your thoughts?
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This storm is such a tease. I know folks in Safety Harbor and St. Petersburg are probably getting flooding, yet in Largo not a single drop.



Member Since: August 31, 2009 Posts: 0 Comments: 5628
around here, this is our worst nightmare storm, happened in 1921.....................PINELLAS COUNTY --
The last major hurricane to directly hit the Bay area was 90 years ago in Tarpon Springs.

It couldn't have been a more different day in Tampa bay back then. Residents were bracing as a Category 3 storm made landfall.

"It was also the worst case scenario," said Bay News 9 Chief Meteorologist Mike Clay. "It came in North of Indian Rocks Beach, so it pushed all the water up into the bay."

The National Weather Service estimates the storm surge in areas like downtown Tampa were as high as 10.5 feet.

"The area here is very susceptible to storm surge because of the shallow water in the bay and shallow water off shore," Clay said.

All of this from a storm Clay says could have been worse since it happened so late in the season.

"It was probably weakened by windshear and it was probably weakened by colder water out over the Gulf," Clay said. "But what a lot of people don't realize, we're more likely to be hit in October than any other month by far."

The hurricane is believed to be the last one that directly hit the Bay area. But nine decades shouldn't lead to ignoring the threat.

"It gives people a little bit of false sense of security to say well, we haven't been hit in 90 years. We've had a lot of close calls," Clay said.

The Bay area has grown and changed dramatically during that time but the threat of a hurricane remains the same.

The National Weather Service says there were only three confirmed deaths from that storm.

Five others were unconfirmed. Of those who died - most drowned in the storm surge.
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Quoting TampaBayStormChaser:
Severe Thunderstorm just moved over me in Northeast Saint Petersburg. It has been raining moderately to heavily for about a half hour. I'd estimate the winds at
40 mph or slightly above that. Clearwater/St.Pete Airport recorded 40 mph winds. I saw rotating clouds but it did not become a funnel or tornado at least from where I could see.
oh yeah its bad there,all red and yellow on radar,not a drop by me, like it stopped and said, I aint going to your house lol..gee
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Hi everyone, I just finished a blog entry on both Hurricane Bud and Invest 94L. It's unfortunate that Bud is now forecast to still be a hurricane at the time of landfall. For anyone interested in reading:

Link

I also wanted to share a picture I snapped from the roof of NOAA's AOML building (where the Hurricane Research Division is located) earlier today:



There was a 61 knot wind gust recorded on the island earlier today. It was pretty intense!
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Quoting stormpetrol:
The Bad weather here in Grand Cayman just won't ease up, now we have terrible lightening and thunder this evening something we never had when 94L was in our area, weird!


94L taking one last crack at us :-)

Actually a rather small cloud but intense it seems
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Quoting LargoFl:
....................Look at this lol..not a drop so far by me
Send it in to one of the news stations.
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting stormpetrol:
The Bad weather here in Grand Cayman just won't ease up, now we have terrible lightening and thunder this evening something we never had when 94L was in our area, weird!
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The ECMWF idea of Beryl:
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I'm thinking 14/7/3 for the 2012 Season.
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The Bad weather here in Grand Cayman just won't ease up, now we have terrible lightening and thunder this evening something we never had when 94L was in our area, weird!
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....................Look at this lol..not a drop so far by me
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Quoting CosmicEvents:
Yes.....it's a pretty definitive shot. The east/west winds(with convection developing) show up very nice. Rarely do we get LB doppler radar on a AOI at this point of cyclogenesis. It's just past Biscayne Bay passing the Dade/Broward border at the moment.



incredible this year. i want to watch them from afar and not up close and personal though. Im not a get in a storms face type of person but i respect those who are
Member Since: April 26, 2006 Posts: 5 Comments: 3222

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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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