outlook 2013 atlantic hurricane...
TRANSCRIPT
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
