Monday, July 17, 2017

Pattern Change This Week Will Bring Heat Relief to Northern Plains, Rockies and Heat Will Build in the Midwest, East

Linda Lam
Published: July 17,2017

If you have been wishing for a change in the weather pattern, you may be in luck this week.
Early to mid-week, the jet stream will become more zonal and less amplified across the northern tier of the U.S., meaning more of a west-to-east track, and the subtropical ridge of high pressure will shift eastward.
This upper-level shift in the pattern will bring weather changes to much of the U.S., at least for part of this week. Below, we take a closer look at what changes to expect.

Some Relief From Heat and Drought

The northern Rockies and northern Plains have been baking in intense heat for much of July. This has helped to worsen the drought in portions of the Dakotas and Montana, which developed quickly in late May.
(MORE: Heat Wave Has Intensified Nation's Worst Drought)
The good news is that this pattern change will finally bring some relief to the extended period of hot and dry weather.

Five Day Forecast
 Instead of high temperatures 10 to 15 degrees warmer than average, highs will be closer to average for mid-July. This means, for many areas, temperatures will still be hot. Highs near the 100-degree mark will be replaced with temperatures in the 80s and lower 90s in many locations.
Precipitation chances will also increase with several disturbances expected to move through the region. Dew points will also likely rise this week in much of the Dakotas and eastern Montana. This will also help increase the chance for some rainfall. A few strong to severe storms are even possible from the eastern Dakotas into northern Minnesota.
Although a widespread, heavy rain is not expected, this pattern shift is a small step in the right direction for the region.

Heat Shifts Into Midwest, East

Meanwhile, areas from the Midwest to the East will see rising temperatures this week. This change will take place as the upper-level trough, or southward dip in the jet stream, that has dominated the East for the last few weeks lifts out of the region.
This shift in the jet stream will allow above-average temperatures to slide into parts of the Midwest and East, making it feel more like mid-summer.

Midweek Forecast
Early week, highs up to 10 degrees warmer than average will spread into areas of the Midwest and Great Lakes. Temperatures will climb into the upper 80s or low 90s in Minneapolis and Chicago at times through Thursday, while St. Louis is expected to see temperatures around the century mark from midweek into next weekend.
(MAPS: 10-Day Forecast)
When factoring in the humidity, heat index values of 105-110 degrees will be possible in parts of the lower Midwest this week, including Kansas City and St. Louis. The National Weather Service has issued excessive heat watches from eastern Kansas into northern/central Missouri and west-central Illinois.
By midweek, highs will be above average from the mid-Atlantic and Northeast.
Washington D.C. is expected to see highs in the mid 90s mid- to late week, while highs will be close to 90 from New York City to Boston. This will be a noticeable change from the 60s and 70s that ended last week in parts of New York and New England.

Break From Rain, Storms in Parts of Southeast

In the Southeast, the ridge of high pressure will bring slightly hotter temperatures and a decrease in the chance for showers and thunderstorms by midweek.
This break from the wet weather will be welcomed across much of the region. Many areas of the South have seen a wetter-than-average summer so far. Birmingham, Alabama, has seen its second wettest summer through July 13, with over 14.5 inches of rainfall since June 1.
(MORE: Mid-Summer Report Card)
Showers and thunderstorms may still develop mid-to-late week, especially toward the Gulf Coast, but the coverage of wet weather will not be as widespread.

Midweek Forecast
The decrease in rainfall and cloud cover, however, will also allow temperatures to climb into the 90s, and dew points will likely remain in the muggy 70s for most areas, as well.
Rain chances are expected to increase slightly, once again, late week or next weekend for much of the region.
(MORE: Why Pop-Up Summer Thunderstorms Are Among the Hardest Weather to Predict)

Moisture Increases in the Southwest

Meanwhile, as the upper-level ridge shifts east bringing drier conditions to the Southeast, this shift has allowed moisture to increase across the Southwest.

Southwest Forecast
The result is more widespread showers and thunderstorms across New Mexico, Arizona, southern Utah and much of Colorado. Through Thursday, parts of Arizona, northern New Mexico and southern Colorado may receive more than an inch of rainfall.
(NEWS: Deadly Flash Flooding in Arizona)
The heavy downpours could cause more localized flash flooding in the Southwest. Damaging wind gusts and blowing dust are also possible threats from some of the storms.
In addition, high temperatures will also be slightly cooler than average due to the increase in cloud cover and storms.
MORE: California, Canada Wildfires July 2017 (PHOTOS)

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