A mix or rain, snow and fog is expected in Denver on Thursday ahead of a massive storm, the National Weather Service in Boulder said.

Thursday is expected to have patchy fog before 8 a.m. then partly sunny with temperatures likely to reach a high of 45 degrees and winds between 5 and 8 mph, according to the weather service.

There is a 20% chance of rain and snow showers between 1 p.m. and 4 p.m., then a slight chance of rain showers after 4 p.m., the agency said.

Overnight temperatures are expected to drop to a low of 30 degrees in Denver with mostly cloudy skies and winds between 5 and 7 mph, the weather service said.

There is a 30% chance of rain and snow showers before 8 p.m., then a chance rain and snow showers between 8 p.m. and 11 p.m., and a chance of snow showers after 11 p.m., the agency said

More snow and rain is expected Friday and a winter storm watch was issued from Friday night through Sunday night in Denver, the weather service said.

“Denver, the western Denver suburbs, Fort Collins, Boulder, Castle Rock and Greeley can expect accumulations of 15 to 25 inches, with up to 30 inches near Boulder and Fort Collins,” Denver Gazette news partner 9NEWS reported.

Updated storm total snow map! 15-25″ expected across urban corridor with up to 30″ in Boulder and Fort Collins. 2 to 4 feet of snow in the foothills. Lower amounts west of Continental Divide and east of DIA. #COwx pic.twitter.com/ykTuxhsuiC

— NWS Boulder (@NWSBoulder) March 11, 2021

Details and potential impacts, and what to know for our upcoming winter storm. Make preparations today and Friday. #COwx pic.twitter.com/s4MLd4azVg

— NWS Boulder (@NWSBoulder) March 11, 2021

Here’s the rest of this week’s forecast from the National Weather Service:

Friday: Mostly cloudy, with a high near 43 degrees and winds between 3 to 8 mph. A chance of snow before noon, then a chance of rain and snow between noon and 5 p.m., then a chance of rain after 5 p.m. Chance of precipitation is 40%. Little or no snow accumulation expected.

Saturday: Snow. The snow could be heavy at times. High near 34 degrees and winds between 6 to 13 mph, with gusts as high as 20 mph. Chance of precipitation is 100%.

Sunday: Snow. High near 33 degrees. Breezy. Chance of precipitation is 90%.

Monday: Partly sunny, with a high near 39 degrees. A slight chance of snow before 11 a.m.