FZAK30 PAFC 252337 ICOAFC Sea Ice Outlook for Western and Arctic Alaskan Coastal Waters National Weather Service Anchorage Alaska 337 PM AKDT Thursday 25 April 2019 ...APRIL 2019 MONTHLY SEA ICE OUTLOOK... Looking at the big picture, the weather patterns during April were somewhat variable, causing a wide variation in sea ice concentration throughout the month. Persistent northerly winds over the past couple weeks have allowed new sea ice to form across much of the northern Bering Sea as well as along the west coast of Alaska. While the sea ice concentration has increased across these areas, this relatively new sea ice is still less than one foot thick and will likely melt quickly when southerly winds return to the region. The thickest ice within the Bering Sea is between Saint Lawrence Island and the Bering Strait, and some multi-year ice has recently been reported in this area as well. As we look forward into break-up through July, sea ice is expected to melt much faster than average through the Bering Sea and southern Chukchi Sea, however some sea ice could remain well into summer and potentially affect navigational waters where there is multi-year ice. Farther north, there is quite a bit of multi-year ice across the northern Chukchi Sea and southern Beaufort Sea. While the area of sea ice south of the multi-year ice will gradually melt during the late spring and early summer, the multi-year ice will melt much slower and could affect navigational waters well into the summer months. We will continue to keep a close eye on the location of the multi-year ice. Detailed information can be found in each pertinent section below. Please note that while the dates provided below are what currently look to be the most likely outcome and are weighted toward a very early breakup for the Bering sea and Chukchi Sea, this season has been quite unusual and predictability is lower than usual. ...BREAK-UP OUTLOOK FOR THE BERING SEA... Satellite imagery has been indicating the presence of multi-year ice floes within the northern Bering Sea, and there have been reports from observers that confirm what we have seen on the imagery. While these floes may move back north of the Bering Strait, they could remain in the vicinity and will melt much slower than the remainder of the ice pack, potentially affecting navigation in this area longer than expected. Sea ice within Etolin Strait is mainly newly-formed sea ice that has grown during April. It is expected to reach 3 tenths sea ice concentration for the season and quickly become sea ice free for the season by the end of April. From Etolin Strait to Cape Romanzof, the only remaining shorefast ice is within Baird Inlet. This ice is expected to no longer be shorefast by the 2nd week of May. Sea ice concentrations beyond the shorefast ice to 20nm offshore are expected to reach 3 tenths concentration then sea ice free for the season by the end of April. For Cape Romanzof to Kwikpak, the remaining shorefast ice at the mouth of the Yukon River is expected to no longer be shorefast by the end of April. Sea ice within 20nm offshore is expected to reach 3 tenths concentration then sea ice free for the season by the end of April. From Kwikpak to Unalakleet, the only remaining shorefast ice is west of Saint Michael. That ice is expected to no longer be shorefast by the end of April. Sea ice within 20 nm of shore is expected to reach 3 tenths concentration then sea ice free for the season by the first week of May. Waters near Shaktoolik are expected to reach 3 tenths concentration then sea ice free for the season by the end of April. Sea ice within Norton Bay is expected to no longer be shorefast by the middle of May, to 3 tenths concentration then sea ice free for the season during the 3rd week of May. For Golovin Bay, sea ice is expected to no longer be shorefast by the middle of May, reach 3 tenths concentration then be sea ice free for the season by the end of May. Along the Nome coast from Port Safety to Cape Rodney, sea ice is expected to reach 3 tenths concentration by the 2nd week of May, and to be sea ice free for the season by the 3rd week of May. Sea ice concentration within Norton Sound is expected to reach 3 tenths concentration for the season by the 2nd week of May and be sea ice free for the season by the 3rd week of May. For Port Clarence, sea ice is expected to no longer be shorefast by mid-May. Sea ice concentration is expected to reach 3 tenths then sea ice free for the season by the first week of June. The Bering Sea is expected to be sea ice free south of 60N by end of April. The Bering Sea south of Saint Lawrence Island is expected to be sea ice free by the first week of May. The Bering Sea from Saint Lawrence Island to the Bering Strait is expected to be less than 3 tenths concentration by mid-May. The Bering Strait to 20nm north and south of the center line is expected to be sea ice free for the season by the first week of June. The Bering Sea is expected to be sea ice free for the season by the first week of June. ...BREAK-UP OUTLOOK FOR THE CHUKCHI SEA... Looking at the big picture for the Chukchi Sea, sea ice is relatively thick compared to the past couple winters through much of the Chukchi Sea. There is also an area of multi-year sea ice that has drifted through the central Chukchi Sea to the Bering Strait area. While sea ice along the coastline will likely break up slightly slower than last year, the area of multi-year sea ice will likely linger offshore quite a bit longer. It is possible that some of this ice will drift closer to the coast and into navigational waters after the near-shore break-up has completed depending on weather patterns during break-up. This is especially true closer to Wainwright and Utqiagvik. Therefore, please keep an eye on the current sea ice analyses and forecasts well into the summer if you plan to be in these areas. From Wales to Espenberg, the remaining shorefast ice is expected to no longer be shorefast by the first week of May. Sea ice concentrations within 20 nm of shore are expected to be less than 3 tenths by mid-May and sea ice free for the season by the 3rd week of May. Sea ice concentrations within Kotzebue Sound are expected to no longer be shorefast by the first week of May, then less than 3 tenths and sea ice free for the season by the 3rd week of May. Sea ice along the coast from Cape Krusenstern to Point Hope is expected to no longer be shorefast by the 2nd week of May. Sea ice concentrations out to 20 nm from the coast are expected to reach 3 tenths by the middle of May and become sea ice free for the season by the end of May. For Point Hope to Icy Cape to 170W, sea ice concentration is expected to reach 3 tenths by the end of June and be sea ice free for the season during the first half of July. This will be highly dependent on where the multi-year ice moves over the next couple months. For navigational waters from Point Hope to Wainwright, sea ice is expected to no longer be shorefast during the second half of May. Sea ice concentrations within navigational waters are expected to reach 3 tenths for the season by the end of June and be sea ice free for the season during the first half of July. It is also possible that some multi-year sea ice will affect navigational waters through the end of July. For Wainwright to Utqiagvik, sea ice is expected to no longer be shorefast by the end of June. Sea ice concentrations within navigational waters are expected to reach 3 tenths for the season by the first half of July, but may not reach 3 tenths until late July or early August. This is highly dependent on where the multi-year sea ice moves as break-up progresses, so please check back for updates during the next couple months. It is possible sea ice concentrations will be sea ice free for the season by the end of July but more likely sometime in August. ...BREAK-UP OUTLOOK FOR THE BEAUFORT SEA... From Point Barrow to Demarcation Point, sea ice is expected to no longer be shorefast during the first half of July. $$ Schreck