NWS Announces Changes to Marine Zones around the Apostle Islands

Zone Changes

Effective *March 30, 2021, one nearshore marine zone will be added for the NWS Weather Forecast Office (WFO) in Duluth, MN (DLH). Please read the overview sections below for the details. (*Backup date April 1, 2021; Implementation date is subject to delay due to weather or other technical challenges.)

Overview

The NWS Weather Forecast Office (WFO) in Duluth, MN (DLH) will add 1 new marine zone to encompass the Apostle Islands beyond 5 NM from the mainland. The zone will extend from the current breakpoint between LSZ146 (Port Wing to Sand Island WI) and LSZ147 (Sand Island to Bayfield WI) out an additional 5 NM from the islands that make up the remaining portion of the Apostle Islands that are located more than 5 NM from the mainland (see map below for details) all the way to the midpoint of LSZ148 (5 NM southeast from Madeleine Island) and then return back along the current boundary of LSZ147 (Sand Island to Bayfield WI). This change will remove a large portion of the offshore zone LSZ162 (Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM) and turn it into a near shore zone for which small craft advisories can be issued.

Zone Changes Old Versus New

Justification

The current zone that covers the outer Apostle Islands is part of a huge offshore marine zone (LSZ162), and the forecast for this zone often doesn't reflect the conditions that are observed in the more near-shore influenced Apostle Islands. Adding this area to a near shore forecast will allow small craft advisories to be issued for this geographical area which is a huge advantage due to the high density of inexperienced mariners in this nationally recognized destination (Apostle Island National Lakeshore). There have been incidents where users of our forecast would not have noted the wind shifts that occur around these islands if they were solely using the offshore forecast. An example of this is on August 30, 2018, several people perished while kayaking in this area which occurred within an "Open Waters" zone.

These zone changes require partners and users to take appropriate action to receive the new zone products using the Universal Generic Code (UGC) zone code format (Z) listed in Table 1. Products affected by this change are listed in Table 2. 

Table 1: WFO DLH's Affected Marine Weather Forecast Zones

Removing part of Marquette, Michigan's WFO offshore zone and turning it into a nearshore zone for Duluth, MN's WFO.

Table 2: WFO DLH's Products Affected by These Changes

If you are affected by these changes, take the appropriate action so your system(s) recognize the new zone (Z) Universal Geographic Codes (UGC) and the new zone alignments. 

Updated public and fire zone map shapefile are available for download at:

https://www.weather.gov/gis/AWIPSShapefiles

The proposed changes to the DLH zone boundaries have been closely coordinated with local partners and customers to be ready for implementation on March 30, 2021. (*Backup date April 1, 2021; Implementation date is subject to delay due to weather or other technical challenges.)

If you have any questions, please contact: