Long Island Sound Marine Zone Changes

Zone Changes

Effective March 30, 2021, marine zone ANZ330 for NWS Weather Forecast Office (WFO) in Upton, NY (OKX) will be separated into two different zones. If March 30, 2021 is declared a Critical Weather Day by the NWS, this implementation will be postponed to April 01, 2021. Please read the overview sections below for details. 

Justification to Split Marine Zone ANZ330

NWS Weather Forecast Office (WFO) in Upton, NY (OKX) will split marine zone ANZ330, the Long Island Sound East of New Haven CT/Port Jefferson NY, into two marine zones using a line from the mouth of the Connecticut river to Orient point. Wave heights can be around 1 to 4 feet higher around the transitional waters of the Long Island Sound where the sound waters meet the open ocean when compared to those of the central sound. These higher wave heights are often the product of the interaction between wind waves generated in LI Sound and incoming ocean swells, enhanced by current/wave interactions. In a typical summer-time SW flow regime, wind waves heights across central sound will range from 1 to 2 feet, but across the Long Island Sound east of the Connecticut River, significant wave heights can be 3 to 4 ft or higher when influenced by energetic ocean swells and tidal currents.

Having these two distinct marine areas within the same zone creates a problem for the Coastal Waters Forecast (CWF). CWF formatters in ANZ330 will average the gridded forecast across the zone, masking the detail and risk posed by the higher wave heights in the transitional waters.  This poses a disservice to marine partners who rely on the CWF for accurate marine forecasts. In fact, consistent feedback over the years from marine partners, mariners, academia (UCONN New London), etc. has been that NWS NY wave forecasts in the mouth of LI Sound and the Race are un-representative of conditions in the rest of E LI Sound and our forecasts for that area. We are fortunate to have a high resolution nearshore model in NWPS that can skillfully resolve the forecast challenges of complex "shallow" bathymetry, tidal levels and variations, and swell/wind wave interaction. Although there are no observing stations in this area, the correlation between "observed" sea state in the extreme eastern sound and NWPS output presents a strong opportunity for improvement in wave forecasting service in the proposed marine zone (outlined below) in wind wave/ocean swell interaction regimes. Splitting ANZ330 into two different marine zones will allow us to take advantage of this, and provide an improved forecast service for users.

Current ANZ330 Configuration

New ANZ331 & ANZ332 Configuration

The current marine zone of will be converted into two separate zones.

Universal Geographic Codes (UGC): Current Marine Zone Forecast Name -------------------------------------------
ANZ330: Long Island Sound East of New Haven CT/Port Jefferson NY

Universal Geographic Codes (UGC): New Marine Zone Forecast Name -------------------------------------------
ANZ331: Long Island Sound East of New Haven CT/Port Jefferson NY to the Mouth of the Connecticut River
ANZ332: Long Island Sound East of the Mouth of the Connecticut River

Table 1: NWS products affected by these marine zone changes are listed below.
 

NWS partners and users should take the appropriate action to ensure systems recognize the new UGC’s (ANZ331 and ANZ332) and new zone alignments and names. Updated marine zone shapefiles are online at: https://www.weather.gov/gis/MarineZones For a graphical depictions of these changes please refer to the link below: https://www.weather.gov/OKX/LISoundMarineZoneChanges

For more information, please contact:
Nelson Vaz
Warning Coordination Meteorologist
NWS New York, NY
Nelson.Vaz@noaa.gov 631-924-0037

Da'Vel Johnson
Marine Team Lead
NWS New York, NY
Da'Vel.Johnson@noaa.gov

Chris Birchfield
Marine Program Manager NWS Eastern Region
Bohemia, NY. 11716
Chris.Birchfield@noaa.gov 631-244-0125

NWS National Service Change Notices are online at: https://www.weather.gov/notification/