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:
It's hard not to root for the XTRP :)



It's funny when the average person doesn't understand what XTRP actually is, lol.
Member Since: March 7, 2007 Posts: 584 Comments: 20832
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Quoting hydrus:
I believe it is possible because the NAO is movin towards negative.


If so, youd better be prepared to rewrite the June record books for low temps.

He says the Less amplified ECMWF sagging N-S front is more likely than a trough digging across the E US in early June.

Plus, both of my swim teams swim outdoors, i cant afford for it to be chilly or stormy.
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EP022012 - Major Hurricane BUD

Storm Relative 1km Geostationary Visible Imagery



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Quoting MAweatherboy1:
It's hard not to root for the XTRP :)



Hey! People live on Newfoundland too. :P
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Quoting Grothar:


Where is the dominant center of circulation now?
Member Since: March 22, 2012 Posts: 0 Comments: 723
It's hard not to root for the XTRP :)

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SPECIAL FEATURE...
HURRICANE BUD AT 16.4N 106.4W AS OF 24/2100 UTC MOVING NE AT 8
KT. MAX SUSTAINED WINDS ARE 95 KT WITH GUSTS TO 115 KT...AND
ESTIMATED MINIMUM CENTRAL PRES IS 962 MB. NUMEROUS STRONG WITHIN
90 NM OF CENTER. SCATTERED STRONG ELSEWHERE WITHIN 180 NM OF BUD.
BUD IS LOOKING VERY ORGANIZED ON LATEST SATELLITE IMAGERY SHOW A
BROAD WELL DEFINED EYE AND IS NEAR SYMMETRICAL IN APPEARANCE.
BUD IS EXPECTED TO CONTINUE TO INTENSIFY FURTHER OVER THE NEXT
12 HOURS AS IT CONTINUES ON A GENERAL NE TRACK. THE CENTER OF
BUD IS FORECAST TO APPROACH THE MEXICAN COAST NEAR OR WEST OF
MANZANILLO WITHIN 24 TO 36 HOURS. LARGE SWELL FROM THE STORM
WILL BE REACHING THE COAST IN THIS AREA BY LATE TODAY. INTERESTS
ALONG THE COASTAL MOUNTAINS IN THE MEXICAN STATES OF JALISCO AND
COLIMA SHOULD BE ADVISED OF THE POTENTIAL FOR HEAVY RAINFALL AS
BUD APPROACHES OVER THE NEXT 24 TO 36 HOURS. SEE LATEST TROPICAL
CYCLONE ADVISORY WTPZ22/TCMEP2 KNHC FOR FURTHER DETAILS ON
HURRICANE BUD.
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Quoting HurricaneDean07:

That position is a bit old, The center is about 100 miles ene of that position now.


That would make it right over our home right now. I just flew into FLL. Very rough, but there is not a leaf moving outside.
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Beryl looks like it could be quite large based on the models ive been seeing on the news, and the GFS ECMWF etc.
That could slow its development some.
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Climatologically, we wouldn't expect 94L to recurve so close to the coast. Remember that Alberto almost didn't.
Member Since: March 7, 2007 Posts: 584 Comments: 20832
3 minutes ago:



Pinhole? No.

Probably just convection firing too close to the center.

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Quoting LargoFl:
look where the NWS has it going..this out at 8pm today........................................

Its not coming to central florida, More of North florida/Georgia
Member Since: October 3, 2010 Posts: 40 Comments: 4129
265. Skyepony (Mod)
NASA/GMAO GEOS-5 precip & SLP..KSC/NOLA path.
Member Since: August 10, 2005 Posts: 174 Comments: 38176
Quoting GeorgiaStormz:


not going to happen according to local mets
I believe it is possible because the NAO is movin towards negative.
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263. Gorty
94l... for DMIN the convection is not actually that bad.
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Quoting PedleyCA:


Thanks, my Sister lives NNE of there in Rhinelande.

She's safe then... The storm should remain well south of there.

0z update on 94L is in- no changes.
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Quoting KoritheMan:
I see 94L has flared up today. Now I'm a bit more convinced we'll see Beryl from this.
look where the NWS has it going..this out at 8pm today........................................
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Quoting hydrus:
The GFS sez its winter again in 10 days..


Come on down..Bob Barker say's..


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Quoting MAweatherboy1:

GRLevel 3, central Wisconsin near Merril and Brokaw


Thanks, my Sister lives NNE of there in Rhinelander.
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The GFS sez its winter again in 10 days..
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I see 94L has flared up today. Now I'm a bit more convinced we'll see Beryl from this.
Member Since: March 7, 2007 Posts: 584 Comments: 20832
FLOOD ADVISORY
NATIONAL WEATHER SERVICE TAMPA BAY AREA - RUSKIN FL
806 PM EDT THU MAY 24 2012

FLC103-250200-
/O.NEW.KTBW.FA.Y.0014.120525T0006Z-120525T0200Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000 Z.OO/
PINELLAS FL-
806 PM EDT THU MAY 24 2012

THE NATIONAL WEATHER SERVICE OFFICE IN RUSKIN HAS ISSUED A

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR...
SOUTHERN PINELLAS COUNTY IN FLORIDA.
THIS INCLUDES THE CITIES OF...DOWNTOWN SAINT PETERSBURG...SAINT
PETERSBURG...SAINT PETE BEACH


* UNTIL 1000 PM EDT

* AT 806 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED AN
AREA OF VERY HEAVY RAINFALL ASSOCIATED WITH THUNDERSTORMS OVER THE
ADVISED AREA...LOCALIZED FLOODING IS IMMINENT OR OCCURRING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

KEEP CHILDREN FROM BEING SWEPT AWAY IN FLOODED DITCHES AND DRAINS.
FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND MAY STALL YOUR
VEHICLE. JUST ONE FOOT OF FLOWING WATER IS POWERFUL ENOUGH TO SWEEP
VEHICLES OFF THE ROAD. TURN AROUND...DONT DROWN.

&&

LAT...LON 2785 8258 2780 8258 2778 8261 2770 8263
2769 8271 2767 8270 2767 8267 2764 8266
2765 8270 2763 8269 2762 8274 2764 8276
2772 8275 2782 8284

$$
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Quoting Grothar:


You can clearly seethe "I" right over the Southern Tip of Florida.

That position is a bit old, The center is about 100 miles ene of that position now.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Santa lands begins at the Arctic circle,for us Blue Nose but hey, the maps askew.

4.7 aftershock as well. 2012 May 24 23:46:17 UTC


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Quoting hydrus:
Large trough for early June..


not going to happen according to local mets
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You can clearly seethe "I" right over the Southern Tip of Florida.
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Quoting Patrap:
6.5 earthquake near the North Pole



Magnitude 6.2 - NORWEGIAN SEA


Not really the North Pole...
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Definitely a pinhole:

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The clasps of very high wind shear and low wind shear has allowed 94L to blow up a ball of convection.. Interesting.
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Large trough for early June..
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Earthquake in North Pole??? Reaches for xanax...
Member Since: April 26, 2006 Posts: 5 Comments: 3194
Quoting PedleyCA:


What radar you using to view that, what location.

GRLevel 3, central Wisconsin near Merril and Brokaw, a new warning was just issued, tornado still on the ground and moving at 65mph.
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Quoting Hurricanes101:
where did the LLC go for 94L?

What do you mean?
Member Since: October 3, 2010 Posts: 40 Comments: 4129
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Quoting LargoFl:


PINHOOOOOOOOLE!!!!!!!!!
Member Since: September 3, 2011 Posts: 13 Comments: 3475
Quoting LargoFl:


Action:
Quote
| Modify Comment


Member Since: August 6, 2011 Posts: 0 Comments: 2256

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Quoting GeorgiaStormz:
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.

Which also means the Euro's Set up of the storm is more likely. This means there's a better chance of seeing Beryl out of 94L. The GFS was stronger with the trough which was prohibiting the storm as seen by models, but if the Euro's is more accurate, that means Beryl is more likely.
Member Since: October 3, 2010 Posts: 40 Comments: 4129
Quoting MAweatherboy1:
Confirmed tornado on the ground in central Wisconsin... The storm has good rotation, luckily the tornado is over mostly rural areas.


it has good speed 50mph, but i dont see it lasting.
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where did the LLC go for 94L?
Member Since: March 10, 2010 Posts: 1 Comments: 7818
tornados in Wisconsin? The whole dod limbed world has gone crazy...
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Quoting tampahurricane:
Thanks, so did any rain come down yet?
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Quoting tampahurricane:
I made it through the storm in St. petersburg, im sure you will also. lol
now a flooding warning........ Flood Advisory has been issued for Pinellas County until 10 p.m. Street flooding has already been reported in St. Pete at 38th Avenue North and Haines Road.
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Thanks, so did any rain come down yet?
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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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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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