Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 249 PM EST Wed Jan 30 2019 Valid 00Z Thu Jan 31 2019 - 00Z Sat Feb 02 2019 ...Dangerous wind chills across the Upper Midwest and into the Ohio Valley expected to last through Thursday... ...Heavy snow downwind of the Great Lakes... ...Heavy rain and high elevation snow will ramp up across California in the next few days... An upper level low centered over the Great Lakes driving the blast of Arctic air from the Upper Midwest eastward into the Ohio Valley, Mid-Atlantic and Northeast will stay put through tomorrow. Wind chill values over the Upper Midwest will continue to be in the -40s through Thursday morning, with actual temperatures in the -20s to -30s. In the Northeast, temperatures will plummet to just below zero, and the Mid-Atlantic will see single digit temperatures. These apparent temperatures are creating life threatening conditions, as frostbite can occur quickly and even hypothermia or death if precautions are not taken. Wind chill warnings and advisories are in effect through Thursday afternoon across all these regions--take extra precautions and visit your local NWS website for more information (www.weather.gov). By Thursday afternoon, the upper low will shift north--relaxing the cold, Arctic grip and a gradual warm-up will be expected. Another consequence of the upper low over the Great Lakes is cyclonic flow over the Great Lakes. This will give way to heavy lake effect snow downwind of the lakes. Downwind of Lake Ontario, snowfall totals of 3 to 4 feet in the most persistent snows is possible. Combining this with strong winds, blizzard conditions are expected where there are currently blizzard warnings in effect. Elsewhere, snowfall amounts ranging from 2 to 10 inches downwind of the other Great Lakes will occur through Thursday. However, keep in mind these areas are also experiencing dangerous wind chills. Take extra precautions if traveling. A closed mid-level low approaching the West Coast will begin to skirt the central California coast by Thursday morning. This will bring heavy rainfall particularly to the southern California area along with light snowfall in the Transverse Mountains. There is some instability expected with this system, so embedded thunderstorms will be possible and could lead to enhanced rainfall totals. This area has burn scars from the recent fires--thus there is a slight risk of excessive rainfall possible on Thursday. Another Pacific system will begin to approach the West Coast on Friday night and into Saturday--which will bring heavier rainfall and heavy snow along the Sierra Nevada beyond the short term period. Reinhart Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php