FZAK30 PAFC 271845 ICOAFC Sea Ice Outlook for Western and Arctic Alaskan Coastal Waters National Weather Service Anchorage Alaska 1045 AM AKDT Thursday 27 March 2025 ...MARCH 2025 MONTHLY SEA ICE OUTLOOK... February and March featured a wild swing in the ice extent in the Bering Sea. In mid-February the ice edge had nearly retreated to St. Lawrence Island, along with a large polynya off of the Yukon Delta. However, March featured long duration northerly flow with a storm track along and south of the Aleutians. Despite the large advance in the last six weeks, the ice pack is what I would call, sea surface temperature limited. Sea surface temperatures along the ice edge are 1-2C with areas of 3C not too far to the south. Even with continued northerly winds and arctic air, sea ice will be advected into warmer waters to melt. Those factors combined with the passing of spring equinox means we are likely close to our maximum extent for the season. Ice growth becomes harder and harder as daylight increases rapidly in April. The break-up outlook for this season is tricky due to the rapid retreat then regrowth. Much of the sea ice within 200-300 nm of the edge is new and young ice formed in the last few weeks. It will likely melt faster in these areas than years past. However, northward of the Yukon Delta/St. Lawrence Island, winter temperatures and sea ice have been closer to normal. Finding analog years was difficult once again the closest analog is 2016, however it was not relied upon heavily due to the early melting dates compared to other analog years; the period of 2002- 2006 were all very close in terms of ice extent. As we look forward through the end of “winter” and into the very beginning of break-up season, weak La Nina conditions are expected to shift toward ENSO-neutral conditions which should favor general climatology of the last 10 years. Despite the ice edge recovering recently, the ice will not have had much time to thicken which will likely favor earlier than normal break up across much of the Bering Sea, but likely closer to normal for the Chukchi and Beaufort Seas, where I pushed back break-up dates 1-2 weeks. ...BREAK-UP OUTLOOK FOR COOK INLET... Cook Inlet has very little ice left in late-March, with mainly open water overall. Recent temperatures at night dipping into the low-20s have encouraged some diurnal ice growth that is melting during the day. Cook Inlet is expected to be ice free during the first week of April for the season. ...BREAK-UP OUTLOOK FOR THE BERING SEA... Bristol Bay will be sea ice free for the season during the first week of April. It is possible that new grease ice forms under transient cold air masses at night, however that ice will be diurnal and short-lived. In the last month, there has been a sharp temperature gradient between the Kuskokwim Delta and Bristol Bay as the storm track has been along the Aleutians, near the Alaska Peninsula and Bristol Bay. At one point, retreat and warmer southerly air flow had melted most of the pack ice before regrowing late in the season. These conditions may lead to shorefast ice hanging on longer while the pack ice melts quickly. Within Kuskokwim Bay, sea ice is expected to no longer be shorefast during the first half of May. Sea ice concentration is expected to reach three tenths by the last week of April and become sea ice free by mid-May. Etolin Strait sea ice is expected to reach three tenths during the first week of May and be sea ice free during the second week of May. For Etolin Strait to Cape Romanzof, ice will no longer be shorefast during the first half of May. Three tenths coverage is expected during the first week of May. Ice free conditions are expected by mid-May. For Cape Romanzof to Nunam Iqua, ice is no longer expected to be shorefast during the second half of May. Three tenths coverage is expected during the second half of May. Ice free conditions are expected during the first week of June. For Nunam Iqua to Unalakleet, ice is no longer expected to be shorefast during the second half of May. Three-tenths concentration is expected by the end of May. Ice free or open conditions are expected during the first week of June. For Shaktoolik, three-tenths coverage is expected during late April, and ice free conditions are expected during the first half of May. For Norton Bay, ice is no longer expected to be shorefast during the second half of May. Three-tenths of ice is expected during late May. Ice free conditions are possible in late May but more likely in June. For Golovin Bay, sea ice is no longer expected to be shorefast during late May. Three-tenths concentration of ice is possible during late May. Ice free conditions are not expected until early June. For the Nome area, ice is no longer expected to be shorefast around mid-May. Three-tenths coverage of ice is expected during the second half of May. Ice free conditions are possible by the end of May, but more likely during the first week of June. For Norton Sound, three-tenths coverage is expected around mid-May. Ice free conditions are possible by the end of May, but more likely in early June. For Port Clarence, ice will no longer be shorefast in early June. Three tenths coverage is expected in the first half of June. Ice free conditions are expected mid-June. For the Bering Sea south of 60N, ice free conditions are expected during the first half of May. South of Saint Lawrence Island, ice free conditions are expected during the second half of May. From St. Lawrence Island to the Bering Strait, three tenths coverage is expected during the first half of June. The Being Strait to 20 nm N/S of Center Line, is expected to be ice free during the second half of June. The Bering Sea will be ice free during the second half of June. ...BREAK-UP OUTLOOK FOR THE CHUKCHI SEA... For Wales to Espenberg, ice is no longer expected to be shorefast during early June. Three tenths coverage is expected in the second half of June. Open water is expected by the end of June. For Kotzebue Sound, ice is no longer expected to be shorefast in early June. Three tenths coverage is expected around mid-June, and open water in late-June. For Cape Krusenstern to Point Hope, ice is no longer expected to be shorefast in late-May. Three tenths coverage is expected during the first half of June. Open water is expected in the second half of June. For Point Hope to Wainwright, ice is no longer expected to be shorefast around mid-June. Three tenths coverage is possible by the end of June, but more likely into July. For Wainwright to Barrow ice is no longer expected to be shorefast in late June. ...BREAK-UP OUTLOOK FOR THE CHUKCHI SEA... For Point Barrow to Cape Halkett, ice could no longer be shorefast by the end of June, but is more likely in July. For Cape Halkett to Flaxman Island, ice could no longer be shorefast by the end of June but is more likely in early July. $$ Lawson