Many in the East are experiencing their first big taste of fall, but that will change heading into the weekend as the pattern changes and colder, snowier weather moves west.

The pattern for the first half of this week features a strong ridge of high pressure across the west and Plains, with the jet stream rising into central Canada and then plunging south across the east.

By the end of the week, a high pressure system will settle in the east, while a truncated low pressure system will prevail in the west.

Temperatures in the East will warm from 50 to 70 degrees by this weekend. Some areas near the Gulf Coast and Florida will climb back into the 80s.

The reversal will be complete late Friday after an upper level low pressure system moves into the Four Corners region, bringing colder temperatures and snow in some areas.

(​Meteorological marking: The border between rain and snow)

During this transition, temperatures will drop by 20 to 30 degrees across much of the West.

For example, in Salt Lake City and Rapid City, South Dakota, high temperatures will drop from the low 80s to the 40s or 50s in just over 48 hours. Many in the Intermountain West will experience frost this weekend.

Even Phoenix, which just ended its incredible streak of three straight weeks of record daily temperatures, will see lows dipping into the 50s this weekend.

Jonathan Belles is a graphic meteorologist and author for Weather.com for 8 years and also helps produce videos for The Weather Channel en español. His favorite weather is tropical weather, but he also enjoys covering severe weather events, news reports, and winter storms. He is a two-time graduate of Florida State University and a proud graduate of St. Petersburg College.