Weather Changes Ahead: 4 Things To Watch This Week

Linda Lam
Published: June 25,2017
An upper-level pattern shift will result in some welcome changes in the weather for much of the U.S. early this week. On the negative side, severe weather may return to parts of the Plains and Midwest.
(MAPS: 10-Day Forecast)
Here's what to expect:

1) Northern-Tier System Brings Storms, Temperature Changes

Scattered showers and storms will begin to fire up from the northern Plains to the Upper Midwest Tuesday into Wednesday ahead of a new low-pressure system. Severe thunderstorms will be possible in those regions with the main threats being damaging winds and large hail.
(MORE: Severe Weather Returns to Plains, Midwest)
Warmer temperatures will also return to the Midwest on southerly winds ahead of this system.

Wednesday's Thunderstorm Forecast

(MAPS: Weekly Planner)
The chance for storms may last through late week in much of the Midwest, as this system slides eastward and another system moves into the region late week. Showers and thunderstorms may also develop in the Northeast by late this week.
A few strong to severe thunderstorms are possible with the second system, but it is too early for details so be sure to check back to weather.com for updates.

2) Cool Start to the Week and Then Summer Returns

A strong upper-level trough, or southward dip in the jet stream, will be in place over the East to start this week, leading to cooler-than-average temperatures from the Plains to the East Coast through early week.
(MORE: Beginning of Summer's First Full Week Won't Feel Summerlike in the East)
High and low temperatures will be up to 15 degrees colder than average, with highs in the 60s and 70s for much of the Midwest and Northeast. A few record cool temperatures are also possible.

This Week's Forecast

This upper-level trough will weaken and lift out of the Northeast by midweek, just as the low-pressure system mentioned above moves into the Central U.S. This combination will result in a more southerly flow through the Midwest and East ahead of this system, which will allow warmer and more humid conditions to return.
This more summery airmass will see temperatures return to average or above average beginning in the northern Plains on Tuesday. By Thursday, warmer-than-average conditions are expected in the Northeast.
Widespread highs in the 80s and 90s are expected from the Plains through much of the Midwest and East mid-to-late week. Low temperatures will typically be in the 60s and 70s.

3) A Break From the Extreme Heat in the West

A strong upper-level ridge of high pressure, or northward bulge of the jet stream, has dominated the Southwest for the past week. This upper-level ridge has even brought record warmth to the Northwest this weekend.
Hotter-than-average temperatures will continue from the Southwest into the Northwest and Rockies through early week.

Forecast Highs

However, the low-pressure system that will track across the northern tier will also help to suppress this upper-level ridge, with cooler temperatures expected. Temperatures will remain hot in the Desert Southwest and interior California, but conditions will be closer to average for late June.
(MORE: This Is Where 120-Degree Temperatures Have Officially Been Recorded the Most)
Behind the cold front that will push through the Northwest and northern Rockies, temperatures will tumble back toward average or slightly cooler than average. High temperatures in Seattle and Portland will be 20 to 25 degrees on Monday when compared to Sunday's highs. Seattle topped out in the middle 90s on Sunday and Portland reached the century mark.
These cooler than average temperatures will also infiltrate the northern Plains to end the work week.

4) Drier Conditions Early Week

The biggest change in the South this week will be a return to drier conditions for much of the region.
Tropical Storm Cindy brought heavy rain and flooding to parts of the South last week, especially along the Gulf Coast where more than 18 inches of rain was reported.
A cold front will move through the region by early week and high pressure will build in behind this system. This area of high pressure will allow much of the South to dry out.

Early Week Forecast

Dew points will also drop from the 70s to the 50s and 60s by early week, making it feel more refreshing.
A few scattered showers and thunderstorms are possible through early week along the Gulf Coast, but will not be as widespread or bring as much rainfall as this past week.
However, as the area of high pressure slides eastward, a more southerly flow will begin to return. This will result in an increase of shower and thunderstorm activity, especially from the lower Mississippi Valley into parts of the Southeast late week.
MORE: Tropical Storm Cindy, June 2017 (PHOTOS)

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