NOUS41 KWBC 171905

PNSWSH

 

Service Change Notice 17-16

National Weather Service Headquarters Silver Spring MD

305 PM EST Fri Feb 17 2017

 

To:        Subscribers:

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network

           -NOAAPORT

           Other NWS Partners and NWS Employees

 

From:      Allison Allen

           Chief, Marine, Tropical and Tsunami Services Branch

 

Subject:   Addition of Tropical Cyclone Storm Surge Watches

           and Warnings for the Atlantic and Gulf Coasts of

           the Contiguous United States effective on or around

           June 1, 2017

 

Reference PNS16-21 Amended:

 

http://www.nws.noaa.gov/om/notification/pns16-21tcvhlschangesforsswwaaa.htm

 

Effective on or around June 1, 2017, NWS will implement new

Storm Surge Watches and Warnings in association with Atlantic

basin tropical cyclones (i.e., hurricanes, tropical storms and

tropical depressions), subtropical cyclones or post-tropical

cyclones affecting the contiguous United States. The new Storm

Surge Watch/Warning will be integrated into the current NWS

product suite, including all applicable tropical cyclone

graphical and textual advisory products. Definitions for the

Storm Surge Watch and Warning are provided below:

 

Storm Surge Watch: The possibility of life-threatening

inundation from rising water moving inland from the shoreline

somewhere within the specified area, generally within 48 hours,

in association with a tropical cyclone, a subtropical cyclone or

a post-tropical cyclone.  The watch may be issued earlier when

other conditions, such as the onset of tropical-storm-force

winds, are expected to limit the time available to take

protective actions for surge (e.g., evacuations). The watch may

also be issued for locations not expected to receive life-

threatening inundation but which could potentially be isolated

by inundation in adjacent areas.

 

Storm Surge Warning:  The danger of life-threatening inundation

from rising water moving inland from the shoreline somewhere

within the specified area, generally within 36 hours, in

association with a tropical cyclone, a subtropical cyclone or a

post-tropical cyclone. The warning may be issued earlier when

other conditions, such as the onset of tropical-storm-force

winds, are expected to limit the time available to take

protective actions for surge (e.g., evacuations).  The warning

may also be issued for locations not expected to receive life-

threatening inundation, but which could potentially be isolated

by inundation in adjacent areas.

 

Storm Surge Watches or Warnings will not be issued for the

Pacific hurricane basin or Weather Forecast Office (WFO) San

Juan's area of responsibility at this time. 

 

NWS will continue to issue Coastal Flood Watches, Warnings, and

Advisories for flooding of coastal areas associated with storms

that are not tropical cyclones, subtropical cyclones, or post-

tropical cyclones. Most frequently, they will be issued for

winter storms, unusually high tides, or prolonged periods of

strong onshore winds that have pushed water into places it does

not normally go. NWS may issue Coastal Flood Advisories in areas

adjacent to Tropical Cyclone Wind or Storm Surge Watches or

Warnings to alert for potentially dangerous coastal flooding

that is below the threshold established by the NWS for life-

threatening inundation.

 

Changes to the Hurricane Local Statement (HLS) product to

reflect Storm Surge Watches or Warnings issued by WFOs will be

limited to the "NEW INFORMATION" section of the product.  The

subsections for "CHANGES TO THE WATCHES AND WARNINGS" and

"CURRENT WATCHES AND WARNINGS" will include Storm Surge Watches

or Warnings when condition warrant.

 

National Hurricane Center (NHC) Tropical Cyclone Public Advisory

(TCP) products will now list Storm Surge Watches and Warnings,

as applicable, under the "WATCHES AND WARNINGS" section. More

detailed information about the storm surge hazard will be

provided in the "HAZARDS AFFECTING LAND" section.  Storm Surge

Watches and Warnings will be listed in the "SUMMARY OF WATCHES

AND WARNINGS IN EFFECT" section of the Tropical Cyclone

Forecast/Advisory (TCM) product. 

 

In addition, the Storm Surge Watch/Warning graphic previously

issued by NHC as a prototype will become operational at the

start of the 2017 Atlantic hurricane season.  Because Storm

Surge Watches and Warnings are issued on a grid rather than for

entire NWS zones or for entire counties, users are highly

encouraged to use the Keyhole Markup Language (KML) files

available on the NHC website, rather than the Valid Time Event

Code (VTEC), to obtain the most timely and accurate depiction

of the area under a Storm Surge Watch or Warning. This

information is also available in the NWS National Digital

Forecast Database (NDFD).

 

All Tropical Cyclone Watch/Warning (TCV) products issued by NHC

and WFOs for tropical cyclones, subtropical cyclone and post-

tropical cyclones affecting the Atlantic and Gulf coasts of the

contiguous United States will include VTEC for Storm Surge

Watches and/or Warnings when conditions warrant.  The following

VTEC phenomenon and significance codes will be used:

 

     SS.A - Storm Surge Watch

     SS.W - Storm Surge Warning

 

Examples of the WFO and NHC issued TCV products with the new

Storm Surge Watches and Warnings can be viewed at:

 

www.nhc.noaa.gov/experimental/tcv

 

VTEC will continue to be used to activate some dissemination

systems, such as NOAA Weather Radio All-Hazards (NWR). While

users are highly encouraged to use the KML files to display

Storm Surge Watches and Warnings, the NWS recognizes many users

rely on VTEC to parse and disseminate information. VTEC users

should be aware the geographical area associated with a Storm

Surge Watch or Warning using VTEC will be larger than the actual

area of the gridded-based watch or warning as seen in the Storm

Surge Watch/Warning Graphic KML file or the NDFD.  

 

Common Alerting Protocol (CAP) formatted WFO TCV products will

be produced and available through a number of dissemination

sources including the NWS website and NOAAport under the header

XOUS5x. The CAP messages will be used to activate Wireless

Emergency Alerts (WEA) and to populate NWS WFO

watch/warning/advisory maps and point forecast pages. Users of

these products and direct users of the CAP messages should be

aware that the geographical area associated with a Storm Surge

Watch or Warning using CAP will be larger than the actual grid-

based area of the watch or warning as depicted by the NDFD grids

or KML file. The CAP-associated geographical watch/warning areas

will, however, more closely match the true gridded watch/warning

than the areas identified by VTEC, as the CAP-associated areas

will be limited to the portions of zones known to be susceptible

to tropical cyclone storm surge flooding.  

 

Beginning in the 2017 hurricane season, the NWS may request

Emergency Alert System (EAS) and WEA activation for the Storm

Surge Warning. In most jurisdictions, the NWS will not request

EAS or WEA activation for the Storm Surge Watch. Specific

details about changes to the EAS for your area will be provided

by your local WFO in Public Information Statements, on WFO web

pages, and over NWR. Broadcasters should note that if EAS

equipment is not updated and the WFO requests EAS activation

with the new event code(s), EAS encoder/decoder equipment will

usually decode the information received as an "UNKNOWN" 

event code.

 

Storm Surge Watches and Warnings will be broadcast over NWR.

Current NWR receivers providing a limited, caption-like message

display will likely show wording such as "UNKNOWN WATCH" or

"UNKNOWN WARNING."  Receivers equipped with Special Area Message

Encoding (SAME) capability, and properly programmed, should

automatically turn on for counties affected by a Storm Surge

Watch or Warning. The 1050-Hz Warning Alarm Tone (WAT) will

generally be used for the Storm Surge Warning but will not be

used for the Storm Surge Watch.

 

The NWS is seeking comments now through March 4, 2017, on

changing the criteria for issuing tropical cyclone watches and

warnings to include certain land-threatening disturbances that

are not yet tropical cyclones. If this change is adopted, the

NWS would have the option to issue Storm Surge Watches and

Warnings for such disturbances. Please see NWS Public

Information Statement 17-04 linked below for more details:

 

http://www.nws.noaa.gov/om/notification/pns17-04potential_cyclones.htm

 

For more information, please contact:

Jessica Schauer

NWS Marine, Tropical and Tsunami Services Branch

Miami, FL 33165

Telephone: 305-229-4476

Email: jessica.schauer@noaa.gov

  or

Wayne Presnell

NWS Marine, Tropical and Tsunami Services Branch

Silver Spring, MD 20910

Telephone: 301-427-9390

Email: wayne.presnell@noaa.gov

 

National Public Information Statements are online at:

   

http://www.weather.gov/os/notif.htm

 

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