outlook 2013 atlantic hurricane...

Outlook – 2013 Atlantic

Hurricane Season

Steve DiRienzo & Brian Montgomery

National Weather Service

Albany, New York

Who issues the seasonal outlooks ?

The Atlantic Hurricane Seasonal Outlook is an official forecast product of NOAA/NWS’s Climate Prediction Center.

Instituted in 1998, this outlook is produced in collaboration with NOAA/NWS scientists at the Climate Prediction Center (CPC), National Hurricane Center (NHC), and the Hurricane Research Division (HRD).

Definitions

Tropical Depression: tropical cyclone with maximum sustained surface winds of up to 38 mph.

Tropical Storm: tropical cyclone with maximum sustained surface winds of 39 to 73 mph. It is at this point it gets a name.

Hurricane: tropical cyclone with maximum sustained surface winds of 74 mph or greater.

Stages of Development

Graphic from Atlantic Oceanographic and Meteorological Laboratory, Hurricane Research Div.

Hurricane Season North Atlantic, Caribbean Sea & Gulf of Mexico

The NOAA/NWS’s Climate Prediction Center will issue an updated seasonal forecast in August just prior to the historical peak of the season.

Saffir-Simpson Wind Scale – for Hurricane Intensity

Category 1 = 74 to 95 mph

Category 2 = 96 to 110 mph

Category 3 = 111 to 129 mph

Category 4 = 130 to 156 mph

Category 5 = 157+ mph

(Based on peak 1-minute wind at 10 meters, or 33 feet)

Ingredients for Tropical Cyclone Development

Pre-existing surface disturbance with thunderstorms

Ocean temperatures of at least 79F

Atmospheric moisture

Relatively light winds aloft (low vertical wind shear)

Formation north of approximately 5 N NOAA

Vertical Wind Shear

Directional wind shear is the change in wind direction with height

Speed shear is the change in wind speed with height

NOAA

NOAA

2012 Summary and NOAA/NWS’s May 2012 Forecast

May 2012 Forecast

2012 Season

Normals

(1981-2010)

Named Storms

9-15 19 12

Hurricanes 4-8 10 6

Major Hurricanes

1-3 2 3

NOAA/NWS May 2012 Probabilistic Forecast

Season and Activity Type

May 2012 Outlook

Chance Above Normal 25%

Chance Near Normal 50%

Chance Below Normal 25%

2012 Hurricane Tracks

Track Forecast - Hurricane Sandy

NHC Track Error 2008-2012

Tropical Cyclone Forecast Cone reduction in size

The cone represents the probable track of the center of a tropical

cyclone

The size of each circle is set at 2/3 of historical official forecast errors

over the previous 5 years (2008-2012)

NOAA/NWS Predicts Above-Normal Hurricane

Season for 2013

May 2013 Forecast

Normals

(1981-2010)

Named Storms

13-20 12

Hurricanes 7-11 6

Major Hurricanes

3-6 3

NOAA/NWS May 2013 Probabilistic Forecast

Season and Activity Type

May 2013 Outlook

Chance Above Normal 75%

Chance Near Normal 20%

Chance Below Normal 5%

Factors affecting 2013 Forecast

El Nino is not expected to form and suppress hurricane activity (neutral factor)

Warmer Atlantic SSTs as of April-May 2013 (enhancing factor)

Positive Phase Multi-Decadal Signal (Active west African Monsoon, warmer SST’s across tropical Atlantic Ocean and low vertical wind shear – enhancing factor)

Neutral ENSO…

Example El Nino

Current Neutral Conditions

Pacific Niño 3.4 SST Outlook

Figure provided by the

International Research

Institute (IRI) for Climate

and Society (updated 15

May 2013).

•Most of the set of dynamical and statistical model predictions issued during late April and early

May 2013 predict neutral ENSO conditions.

Warmer waters in eastern tropical Atlantic…

Summary – 2013 Forecast Above-Normal Hurricane Season

El Nino is not expected to form and suppress hurricane activity (neutral factor)

Warmer Atlantic SSTs as of April-May 2013 (enhancing factor)

Positive Phase Multi-Decadal Signal (Active west African Monsoon, warmer SST’s across tropical Atlantic Ocean and low vertical wind shear (enhancing factor)

Tropical Cyclone Names

Tropical Storm

Watch: an announcement that sustained winds of

39 to 73 mph are possible somewhere within the specified area within 48 hours in association with a tropical, subtropical or post-tropical cyclone.

Warning: an announcement that sustained winds of

39 to 73 mph are expected somewhere within the specified area within 36 hours in association with a tropical, subtropical or post-tropical cyclone.

Hurricane

Watch: An announcement that sustained winds of 74 mph or higher are possible somewhere within the specified area within 48 hours in association with a tropical, subtropical or post-tropical cyclone.

Warning: An announcement that that sustained winds of 74 mph or higher are expected somewhere within the specified area within 36 hours in association with a tropical, subtropical or post-tropical cyclone.

The warning can remain in effect when dangerously high water or a combination of dangerously high water & waves continue, even though winds may be less than hurricane force.

Tropical Cyclone Update (TCU) replaces the Tropical Cyclone Position Estimate

Provides notice of significant changes in a tropical cyclone that occur in between regularly schedules public advisories.

Beginning in 2013, the TCU will also be issued to provide a continuous flow of information regarding the center location of a tropical cyclone, when watches or warnings are in effect and the center can be easily tracked with land-based radar.

This information used to be conveyed by the Tropical Cyclone Position Estimate (TCE).

Tropical Weather Outlook

The National Hurricane Center is planning to extend the time covered by the Tropical Weather Outlook from 48 hours to 5 days beginning in July or August (pending completion of some technical development).

This probabilistic genesis forecast will be given in 10% increments and will supplement the 48-hour probabilistic formation potential already provided.

Graphical Tropical Weather Outlook

The National Hurricane Center is developing a corresponding 5-day genesis potential graphic they hope to have available this season.

The current Graphical Tropical Weather Outlook which highlights the location of areas of disturbed weather and shows the 48 hour probabilistic genesis potential will remain unchanged.

Probabilistic Storm Surge Products www.nhc.noaa.gov/ssurge/ssurge_products.shtml

Available when a hurricane watch or warning is in effect for any portion of the United States

coast

MOMs = Maximum of the Maximum MEOWs = Maximum of the Maximum Envelope of High Water P-Surge = graphics show the overall chances that the specified storm surge height will occur at each individual location on the map during the forecast period indicated. The probabilities are based on errors during recent years in the official track and intensity forecasts issued by the NHC. Variability in storm size is also incorporated.

Experimental - Data in GIS Formats www.nhc.noaa.gov/gis

NHC provides various advisory products in GIS format

NHC Audio Podcast

Audio podcasts RSS/XML feed for top-of-the-hour briefings will be operational when the media pool is activated.

www.nhc.noaa.gov/audio

The media pool is typically activated when a hurricane watch is issued for any portion of the United States contiguous coastline.

Tropical Cyclone Products Continue for 2012 Season

Blue: Tropical Storm/Hurricane Watch/Warning Issued via HLS

Green: High Wind Watch/Warning Wind Advisory but

Flexible.

NWS Albany Tropical Products Blue & Yellow = High Wind

Watch/Warning & Wind Advisory We have the option to issue Tropical Storm/Hurricane Watch/Warning after coordination with local officials, neighboring NWS Offices and the National Hurricane Center

Yellow = areas most likely to have Tropical Storm/Hurricane Watch/Warning issued

Note: Flood Watches are not issued in combination with any other product

Social Media – Facebook www.facebook.com/US.NOAA.NationalHurricaneCenter.gov

Outreach & Education Campaigns

Daily Tropical Update for the Atlantic & eastern North Pacific basins

Alerts regarding any tropical cyclone

Social Media - Twitter

@NHC_Atlantic Tropical Cyclone Public Advisory – TCP (automated)

Tropical Cyclone Update - TCU (automated)

Tropical Weather Outlook – TWO (automated)

Special messages any time

@NHCDirector Dr. Knabb

@NHC_Surge NHC Storm Surge Group Enhances storm surge forecasts by providing real-time

reports & observations during an event (recourses permitting)

Web Sites

Go to any National Weather Service Forecast Office: www.weather.gov

National Hurricane Center / Tropical Prediction Center: www.nhc.noaa.gov

The End!

Questions?

Stephen.DiRienzo@noaa.gov Ingrid.Amberger@noaa.gov Brian.Montgomery@noaa.gov Kevin.Lipton@noaa.gov