Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

Overview

A significant winter storm tracked northeast across the western Great Lakes bringing with it a swath of heavy, very wet, dense snow during one of the busiest travel days of the year. Disrupting holiday travel, snow was wet and dense leading to very difficult, if not impossible travel conditions at times. In fact, the liquid equivalent within the snowpack was record breaking for the day of November 27th! The combination of high liquid water content and an overall "warmer" atmosphere aloft led to very wet snow, with snow-to-liquid ratios around 5-6:1 throughout the event. For comparison, the "fluffier" snow we typically see with lake-effect snow events are around or higher than 15-20:1. Due to the wet, dense snow another major impact was widespread power outages across the Upper Peninsula and sporadic tree damage.

Strong northeast winds caused blowing snow, sharply reductions in visibilities, and drifting snow. These strong northeast winds also cuae waves to build along the Lake Superior and Lake Michigan shorelines, cause Lakeshore Flooding in some areas.

Not record snowfall, but a record amount of liquid equivalent for November 27th, from the wet, dense snow.

Reports
Impacts & Photos
Social Media Messaging
Environment

Reports:


Event Snowfall Total Map. Isolated higher amounts were reported across the north central.	PNS of Strongest Winds from the Event

Impacts & Photos:


Widespread Power Outages (Courtesy of PowerOutage.US)	Tree Damage in West Ishpeming	High liquid content within the snowpack allows a "blue hue" to appear in some of the drifting snow.

Snow and drifted snow on a bench in Ishpeming.	Baraga (Courtesy of Ann Lanala)	Baraga (Courtesy of Ann Lanala)

Social Media Messaging

Messaging on social media began Saturday morning as confidence grew!


Updated Saturday Morning	Update Saturday Evening	Update Sunday Morning	Update Sunday Evening

Update Monday Morning	Update Monday Evening	Update Monday Evening	Update Tuesday Morning

Update Tuesday Evening	Update Tuesday Evening	Update Tuesday Evening	Radar Update Wednesday Morning

Messaging Timeline:

Land Based:	Marine Based:
High uncertainty the week prior to the event, but mentions of the potential were in AFDs	Mentions of gale forecast winds in the HWO Saturday afternoon
Mentions in the Hazardous Weather Outlook began Saturday, November 23nd	Gale Watch issued for Lake Superior and nearshore of Lake Michigan issued Sunday Morning.
Winter Storm Watch issued morning of Monday, November 25th	Initial Situation Report sent to Marine Partners Monday morning for high-end gales.
Lakeshore Flood Advisories for Lake Superior shoreline issued evening of Monday, November 25th	Gale Watch updated to Storm Warning Tuesday morning.
Winter Storm Warnings, Advisories, and Blizzard Warning issued morning of Tuesday, November 26th	Updated Situation Report send to Marine Partners Tuesday Morning for upgrade highlights.
Lakeshore Flood Warnings upgraded for Lake Superior morning of Tuesday, November 26th
Lakeshore Flood Advisory issued for NW Lake Michigan & Bay of Green Bay morning of Tuesday, November 26th
Briefing packet sent to partners late Tuesday Morning.

Environment


300 mb Height and Wind at 15z (10 am EST) Wednesday, November 27	500 mb Height and Vorticity at 15z (10 am EST) Wednesday, November 27	700 mb Height and Relative Humidity at 15z (10 am EST) Wednesday, November 27	700 mb Height, Wind, Theta-e, and Theta-e Advection at 15z (10 am EST) Wednesday, November 27

850 mb Height, Wind, Theta-e, and Theta-e Advection at 15z (10 am EST) Wednesday, November 27	850 mb Height and Temperature at 15z (10 am EST) Wednesday, November 27	925 mb Height and Wind, and 850 mb Temperature, at 15z (10 am EST) Wednesday, November 27	Mean Sea Level Pressure and Regional Radar at 15z (10 am EST) Wednesday, November 27