Five Things To Know About This Week's Weather

Linda Lam
Published: December 3, 2017

A big pattern shift will be felt across the U.S. in the upcoming week, with noticeable changes ahead for many locations.

This will be due to a change in the jet stream, featuring a strong upper-level ridge of high pressure, or northward bulge of the jet stream, developing over the West and a deep upper-level trough, or southward dip in the jet stream, over the East.

Below we take a closer look at what to know about the weather this week.

1. Early Week System Will Bring Rain, Snow To Central, Eastern U.S.

A low-pressure system will push through the central and eastern U.S. to begin this week, kicking off a major pattern change.

On Monday, rain and thunderstorms are possible from the Great Lakes southward into eastern Texas and the lower Mississippi Valley, with snow and strong winds in the northern Plains and Midwest. Blizzard conditions are likely in parts of the Dakotas and Minnesota.

A few strong to severe thunderstorms may accompany the front on Monday from the mid-Mississippi Valley southward into the Ozarks.

(MORE: Early Week Storm Will Bring Rain, Snow, Thunderstorms)

Early Week Forecast

This system will continue tracking eastward bringing rain from New England to the South Tuesday into Wednesday.

This cold front may linger off the East Coast and a wave of low pressure may develop along this boundary late week. At this time, it appears that this system will be far enough offshore to avoid major impacts along the coast, but there is a chance it could be far enough west that some rain or snow showers could develop along the mid-Atlantic and Northeast coasts late week.

2. Big Temperature Changes Ahead

Behind the early week system, temperatures will take a noticeable drop as the southward dip in the jet stream moves into the East and allows colder temperatures to surge southward. 

(MORE: Cold Blast This Week in the Midwest and East)

Ahead of this system, temperatures will be well-above average from the Plains to the East Coast but will return to below-average levels mid-to-late week.

Forecast Highs

High temperatures in the Midwest and much of the Northeast will be in the 40s and 50s to start the week, but will only reach the teens, 20s and 30s by late week. Farther south, highs in the 60s and 70s will be replaced with temperatures topping out only in the 40s and 50s.

Low temperatures will be chilly as well with widespread lows in the 20s as far south as northern Georgia. Record cold temperatures are not anticipated but given the recent stretch of mild conditions across the central and eastern U.S., this temperature change will be a shock to the system for many.

3. Lake-Effect Snow Will Develop Mid-To-Late Week

The upcoming pattern change will also bring the chance for lake-effect snow beginning midweek.

Temperatures should be cold enough over the Great Lakes region to combine with warmer water temperatures resulting in the development of lake-effect snow.

(MORE: What Is Lake-Effect Snow)

The northern Great Lakes will see the lake-effect snow beginning on Tuesday, while the eastern Great Lakes will likely need to wait until Wednesday.

Setup for possible lake-effect snow mid-to-late week.

There is the potential for locally heavy snowfall totals in some of the Great Lakes snowbelts where the wind allows for persistent snow bands to produce moderate to heavy snowfall over several hours. This may include parts of the Buffalo metro area on Wednesday.

In addition, several disturbances may also bring multiple rounds of light snow to portions of the Great Lakes, Midwest and Northeast late week.

4. Santa Ana Wind Event Expected

There is the potential for a strong Santa Ana wind event in southern California as we begin this week.

Potential Santa Ana wind setup in southern California early week.

An area of high pressure will strengthen over the Great Basin early week, resulting in the development of a moderate to strong offshore gradient. In addition, an upper-level trough of low pressure may linger over Arizona and New Mexico, which could help set the stage for a more widespread wind event.

(FORECAST: Los Angeles | San Bernardino | San Diego)

What this means is that gusty offshore winds are currently anticipated to develop for much of this week in southern California. The combination of dry conditions and gusty winds will result in an extreme fire danger.

In addition, the strong winds could down some trees and power lines in the most wind-prone areas in the mountains of southern California.

5. Dry, Foggy Period Expected in the Northwest

A strong upper-level ridge of high pressure will build into the Northwest early week and will remain in place through at least early next weekend.

A ridge of high pressure will bring a period of dry conditions in the West.

The result will be a stretch of dry conditions across the region, likely through next weekend throughout the West. Temperatures will also generally be within a few degrees of average for early December in most of the Pacific Northwest.

This dry stretch will be a welcome change for many. The National Weather Service office in Seattle noted that November recorded 24 days of rain or snow there, which just missed the record of 25 days. In addition, Seattle tied for second most number of days with at least 0.5 inches of rainfall in November, with 8 days.

(MAPS: Weekly Planner)

However, by midweek areas of fog may develop and in some areas the foggy conditions may not completely dissipate. In addition, this could potentially impact air quality in portions of the Northwest.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

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