Low pressure in Prince William Sound combined with a building high pressure system over Alaska's Interior to increase the pressure gradient through the Chugach Range along the north Gulf Coast. This led to high winds through northerly passes along Prince William Sound.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS AFC wrote it up.
Low pressure in Prince William Sound combined with a building high pressure system over Alaska's Interior to increase the pressure gradient through the Chugach Range along the north Gulf Coast. This led to high winds through northerly passes along Prince William Sound. Several transient troughs moved across the area, contributing falling snow to create blizzard conditions in Thompson Pass.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Anchorage, AK wrote its last area forecast discussion before the first event at Mar 4, 4:36 AM AKST, 9 hours 14 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 436 AM AKST Wed Mar 4 2020 .ANALYSIS AND UPPER LEVELS... There is a high amplitude upper level ridge over the central and western Bering. A sharp north to south oriented trough is over eastern Alaska, slowly moving southeastward. Strong northerly flow aloft is between these features, from southwest Alaska through the eastern Bering and Aleutians. At the surface, there is a low centered just south of Prince William Sound with a high over the central Bering. Strong gap winds are occurring from the northern Gulf through the eastern Aleutians. Satellite imagery confirms cold advection is making its way through gaps in the eastern Aleutians and Alaska Peninsula, as cloud streets are visible south of the Chain. Scatterometer winds show gales with storm force gusts south of the Peninsula and, earlier, showed storms across the Barren Islands. Some showers associated with the low south of Prince William Sound are occurring around the Sound and into the Copper River Valley. There are also some showers over the eastern Aleutians associated with the unstable northerly flow. && .MODEL DISCUSSION... The numerical guidance is in rather good agreement through Thursday afternoon. The main forecast challenge will be winds from cold advection and winds through bays and passes along the eastern Aleutians, Alaska Peninsula, Gulf coast and Prince William Sound. Forecast confidence is high. && .AVIATION... PANC...VFR conditions are most likely. Northerly winds could be gusty at times. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Outflow and local gap winds will be the main weather concern through Thursday. An upper low moves slowly east across the Gulf today then weakens and drifts south this evening as upper ridging builds in from the west. A northerly jet on the backside of the trough moves over Southcentral this evening. At the surface, cold air continues to spill into Southcentral and through gaps in the Aleutian Range which keeps a fairly strong thermal gradient between the marine and continental air masses. This, combined with building pressure gradients and increasingly favorable northerly flow aloft, will strengthen outflow and gap winds this afternoon into Thursday. The strongest winds will likely be along the North Gulf Coast where winds will likely hit warning levels by early this evening in the Valdez zone and through the Copper River Delta. Winds will diminish in many areas later Thursday as pressure gradients relax and the upper ridge moves over Southcentral and terminates upper wind support. Cooling temperatures and gusty northeast winds will likely keep the potential for a wind chill advisory over the northern Susitna Valley through tonight. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... (Today through Thursday evening) A series of disturbances aloft will dive south, crossing the lower Kuskokwim Delta, Bristol Bay, and the Alaska Peninsula (AKPEN) through this evening. Here, areas of light snow will continue to affect these locations through the late afternoon or early evening. A ridge of high pressure building into the central Bering on Wednesday will put an end to these after that. Further east across the interior, this region will be sandwiched between the advancing high pressure to the west, and a low near Prince William Sound. As a result, breezy northerly winds will persist through the afternoon, with a few areas of blowing snow possible. These winds should diminish by this evening, with mainly clear and cold conditions persisting. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... (Today through Thursday evening) A few disturbances pass overhead, across the eastern Bering and AKPEN, bringing a few snow showers to the region. These showers become more robust, though, as they pass over ice free waters. A respectable ocean delta-t spread (the difference in temperatures at 850 mb, or roughly 4500 feet, and the ocean water temperatures) are large enough for some weak instability to develop. These "heavier" snow showers also get a boost from orographic lifting as they move ashore across the northern portions of the Peninsula, briefly reducing visibilities at times. This is expected to continue through the afternoon, before diminishing by late evening. South of the AKPEN, downsloping winds off the Peninsula will accelerate as gravity plays a role: helping the air to sink more rapidly while increasing in speed. These increased winds will also get funneled through bays and passes, where a few hurricane force wind gusts remain possible today. High pressure situated to the west and a low in the Gulf is also creating a tight pressure gradient, helping augment this process. However, the Gulf low will move east and weaken as the high moves into the central Bering tonight and Wednesday, allowing winds to subside. Further west, the main item of interest will be a low pressure system currently southwest of Shemya. This low will continue its approach towards the western Aleutians, with its associated surface front moving into that region Wednesday evening through Thursday morning. Sustained gales will precede this front, while also being accompanied by a steady band of precipitation. Here, a few storm force gusts are a distinct possibility. The low reaches the western Bering by Thursday afternoon, with the front stretching from the Pribilof Islands through the eastern Aleutians. Although it'll be in a weakening state, both the low and the front, some sustained gales remain possible. && .MARINE (Days 3 through 5)... The most active pattern will be over the Bering on Friday as a 995 mb low, just west of Saint Paul, slowly weakens on a southeasterly track. This is followed by the next North Pacific low Friday night which continues on a northeasterly track nearing the Pribilof Islands late Sunday. Both of these systems are expected to bring small craft winds with rain along the southern waters and snow from the Pribilofs north. There is some uncertainty on wind speeds with the second system; some adjustments may be needed to increase winds around the core of low. && .LONG TERM FORECAST (Days 3 through 7)... Saturday through the beginning of next week, a wetter and warmer pattern is expected as two low pressure systems move from west to east from the Bering. The first low pressure system over the central Bering on Saturday morning tracks quickly across the southern mainland bringing the first round of snow. Temperatures moderate into the 20s to lowers 30s with the frontal passage, keeping precipitation snow for the southern mainland. Southern Bering and Gulf locations, including the Alaska Peninsula, Kodiak Island and southern tip of the Kenai are expected to warm enough to change snow over to rain. The second system follows quickly behind the Saturday storm, tracking across the Bering Saturday night. This storm will likely pull a warmer maritime air mass further north Sunday into Monday across Bristol Bay. There is high uncertainty on the evolution of the second storm with models varying on the track and strength of this system from run to run. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...Blizzard Warning 131. High Wind Warning 131. Wind Chill Advisory 145. MARINE...Storm Warning 127 130-132 150. Gale Warning 119-121 126 128 129 136-138 155 165 170 172-178 352 411-414. Heavy Freezing Spray Warning 119-139 141 150 165 179 180 414. FIRE WEATHER...NONE. && SYNOPSIS AND MODEL DISCUSSION...CRK SOUTHCENTRAL ALASKA...RMC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PD MARINE/LONG TERM...KH
1 blizzard, 1 high wind. Local standard time, as filed.
Alaska DOT closed the highway through Thompson Pass due to high winds, heavy drifting, and whiteout conditions.
The wind sensor in Thompson Pass measured 77 mph. Reports from DOT personnel confirmed that snow drifting across the highway in Valdez town required the use of pilot cars to keep the roads open.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2020Every state in 2020This day in weather historyWarnings in Alaska, March 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 881665, 881682.