Heavy Rainfall to Bring Flooding Threat to California; Heavy Snow in the Sierra

A strong atmospheric river will bring heavy rainfall to California through the holiday week. The heaviest rainfall is expected on Wednesday in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall is expected in the Sierra Nevada from the atmospheric river, raising concerns for major snow‐load impacts. Travel may be difficult to impossible over the passes. Read More >

Overview

On November 17-18, 2016 atmospheric conditions (moisture transport, strong winds aloft, and low pressure) were ideal for heavy snowfall. Most of the snow fell on November 18, leading to a blizzard warning issued west of the Twin Cities metro region at 3 am. Total accumulated snowfall amounts up to 16 inches were reported in north-central Minnesota. Cities around the Twin Cities region experienced very poor visibility and high wind gusts on November 18 as well.

Snow
Radar
Environment

Snow

Total accumulated snowfall during 48 hours preceding Nov. 19


Blizzard warning issued Nov. 18 at 3 AM CST	Winter storm warning issued Nov. 18 at 6 AM CST	Winter weather advisory issued Nov. 18 at 12 PM CST

Radar:


NEXRAD reflectivity loop on Nov. 18 8-9 AM CST	NEXRAD reflectivity loop on Nov. 18 9:15-10:15 AM CST	NEXRAD reflectivity loop on Nov. 18 4:45-6 PM CST

Environment

Moisture transport from the southern United States, a strong upper-level jet, a trough/low pressure, and high values of precipitable water created a favorable environment for blizzard conditions. These conditions led to heavy snowfall, low visibility, and high winds for most cities around the Twin Cities.


Nov. 18 National Weather Forecast	850 mb RAP analysis loop	700 mb RAP analysis loop


500 mb RAP analysis loop	300 mb 12Z map analysis for Nov. 18 showing strong winds	Precipitable water RAP analysis loop


Montevideo visibility and wind observation graph	Redwood Falls visibility and wind observation graph	Springfield visibility and wind observation graph

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Heavy Rainfall to Bring Flooding Threat to California; Heavy Snow in the Sierra

Summary of November 17-18, 2016 MN Blizzard