####018006563#### FZAK30 PAFC 132140 AAA ICOAFC Sea Ice Outlook for Western and Arctic Alaskan Coastal Waters National Weather Service Anchorage Alaska 139 PM AKDT Friday 13 October 2023 Updated for faster freeze-up along the Alaska coastline north of Unalakleet. ...SEPTEMBER 2023 MONTHLY SEA ICE OUTLOOK… Sea ice has continued to melt significantly especially across the Chukchi Sea through September. While a couple isolated areas of sea ice remain farther south, the main ice pack has melted back to 74N and even as far north as 77N across part of the area. New sea ice growth has been observed within eastern portions of the remaining ice pack, though other areas are still melting. We’ve also noted that while the sea surface temperatures near and west of the Mackenzie River Delta in Canada were quite warm earlier in the summer, they have cooled quite a bit to be more in line with the surrounding Beaufort Sea waters. Looking into freeze-up, El Nino conditions look to strengthen and persist through the end of the year. Overall freeze-up looks like it will be slower than average across Alaska waters. Storm tracks during El Nino tend to bring storms north into and through the Bering Sea, so it will likely be a season of variable sea ice conditions. Detailed information can be found in each pertinent section below. …FREEZE-UP OUTLOOK FOR THE BEAUFORT SEA… Sea ice growth beyond barrier islands is expected by the third week of October. Sea ice concentration within 20 nm of the north coast of Alaska is expected to reach seven tenths during the third or fourth week of October. Sea ice is expected to begin expanding south of the ice pack during the second week of October. The main ice pack will likely merge with the new ice along the Alaska coast by the end of October. …FREEZE-UP OUTLOOK FOR THE CHUKCHI SEA… Along the coast from Icy Cape to Utqiagvik, new sea ice is expected to begin forming beyond protected bays during the third week of October. Navigational waters around Point Barrow are expected to reach seven tenths concentration during the last week of October. For Icy Cape to Utqiagvik west to 170W, the first new sea ice is expected during the last week of October or first week of November. This area is expected to reach seven tenths concentration during the second half of November. From Point Hope to Icy Cape, the first sea ice growth is expected during the third week of October. The timing of freeze-up varies by several weeks from season to season. At this time, sea ice reaching 3 tenths concentration is expected during the first half of November and seven tenths coverage is expected during the second half of November. New sea ice within the ice pack from Point Barrow to 75N and west to 170W is expected during the second week of October. This area is expected to reach seven tenths during the second half of November. Within Kotzebue Sound, three tenths coverage is expected during the first half of November, and seven tenths near mid-November. For Cape Krusenstern to Point Hope to 20 nm offshore, the first ice is expected during the last week of October. Seven tenths coverage is expected during the second half of November. For Wales to Espenberg to 20 nm offshore, three tenths, then seven tenths coverage is expected during the last half of November. For Wales to Point Hope to 170W three tenths coverage ice is expected around mid-November. Seven tenths coverage is expected in the first half of December. For the Bering Strait within 20 nm of Center Line, seven tenths coverage is possible during the last half of November but more likely in early December. …FREEZE-UP OUTLOOK FOR THE BERING SEA… For Norton Sound, three tenths coverage is expected around mid- November and seven tenths coverage is expected by the end of November. For the Yukon-Kuskokwim Delta out to 20 nm offshore, the first ice is expected during the last week of October. Three tenths coverage is expected during mid-November and seven tenths coverage by the end of November. The first ice in Bristol Bay varies from year to year depending on the prevailing weather and temperature patterns. The first ice is expected during the first half of November but may be as late as early December if storms track north into the Bering Sea through November. Three tenths coverage is likely in the first half of December. The ice edge is expected to reach Saint Lawrence Island during the first half of December. …FREEZE-UP OUTLOOK FOR COOK INLET… Ice in Cook Inlet is very dependent on the prevailing ambient air temperature. The transition to El Nino conditions may shift freeze- up later from what has been seen during the last few years that have been in La Nina conditions. Around 75% of El Nino analog years result in a longwave pattern that favors an upper level low pressure south of the Alaska Peninsula in the northeastern Pacific Ocean. If this pattern comes to fruition, the prevailing storm track will be one that brings warmer air to the region, as well as Chinook wind conditions which will drastically affect sea ice in the Cook Inlet area, preventing long periods of arctic air and sea ice getting established. In contrast, the La Nina conditions of the last 2-3 years has allowed for early season arctic air to become established without much displacement. The first ice north of the line from Susitna Delta to Point Possession is expected around mid-November, though it may be delayed to as late as the first week of December. The first ice south of the line from Susitna Delta to Point Possession to the Forelands is expected during the second half of November, though it may be delayed to as late as the second week of December. The first ice south of the Forelands is possible by the end of November but more likely to occur during the first half of December. North of the Forelands, three tenths ice coverage is expected during the first half of December. Seven tenths coverage is expected during the second half of December. The first ice along the coast from Kenai to Nikiski is expected during the second half of December. The ice edge may reach Kalgin Island during the second half of December. $$ Schreck