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Thunderstorms, Heavy Rain and Fire Weather

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The NWS Weather Forecast Office (WFO) in Duluth, MN (DLH) has added one (1) new marine zone to encompass the outer 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.

Access the Forecast

For marine forecasts, check out some of the following resources:

Zone Changes Old Versus New

Old Zone Map

New Zone Map (Current as of March 30, 2021)


Video Explaining the Change

(Click to watch video on YouTube.)

Why was this change made?

The current zone that covered the outer Apostle Islands was part of a huge offshore marine zone (LSZ162), and the forecast for that zone often doesn't reflect the conditions that are observed in the more near-shore influenced Apostle Islands area. Adding this area to a near shore forecast allows 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.


Technical Details

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.

Current Zone Name/ Current UGZ (Z)  New Public/Fire Zone Name / New UGC


Lake Superior west of a line from Saxon Harbor WI to Grand Portage MN beyond 5NM (LSZ162)


Apostle Islands Beyond 5NM from Mainland (LSZ150)






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

Product Name WMO Header AWIPS ID

Nearshore Marine Forecast

Special Weather Statement

Hazardous Weather Outlook

Public Information Statement

Area Forecast Discussion

Special Marine Warnings

Marine Weather Statements

Marine Weather Message

Watch County Notification




















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



If you have any questions, please contact:

Joe Moore
Warning Coordination Meteorologist
National Weather Service
5027 Miller Trunk Highway
Duluth, MN 55811-1442