Prolonged Heat Will Expand From the Plains to the East Coast This Week

Linda Lam
Published: July 4,2016
It will certainly feel like July for much of the Eastern U.S. later this week. A stretch of very hot temperatures and humid conditions is ahead for many from the Plains to the East Coast.
July is the warmest time of year for much of the East and it looks like this July is starting off very hot across the eastern half of the country.
(MORE: July is the Warmest Time of the Year for Much of the U.S.)
Above-average temperatures are expected to spread from the Plains to the Eastern Seaboard through the week ahead. When temperatures are 5 to 15 degrees warmer than average in July, that is noteworthy, considering this is typically a very warm time of year.
What will be the cause of this heat? An upper-level ridge of high pressure will build across the Plains early this week and will expand east. Meanwhile, a southward dip in the jet stream, or upper-level trough, will bring cooler temperatures to portions of the West.
By the end of the week, two areas of high pressure aloft will dominate conditions across the South. This setup will keep the very hot temperatures in place for at least a few days late this week and possibly into next week.

This Week's Upper-Level Pattern

Below we break down the details of how hot you can expect conditions to get in the Plains, Midwest and East.
(MAPS: 10-Day Forecast)

Sizzling Heat Spread East

Above-average temperatures are expected to continue in the Plains early this week, due to an upper-level ridge of high pressure.
The National Weather Service has issued heat advisories from the southern Plains into the lower- and mid-Mississippi Valley. Heat index values of over 100 degrees are likely in many of these areas.

Heat Alerts

High temperatures will climb into the middle/upper 90s northward into the central Plains, with 100s common in the southern Plains much of this week. This translates to temperatures 5 to 10 degrees warmer than average for some cities.
Dallas has not yet hit 100 degrees this year through Monday. This is slightly behind schedule as the average date of the first 100-degree day is June 30. July usually features six days with highs at or above 100 degrees in Dallas, and it looks like a stretch of 100-degree days may be ahead, beginning early this week.
(FORECAST: Dallas | Oklahoma City | Kansas City)
By mid-to-late week, the heat will then spread eastward into the Northeast and South.

Friday's Forecast

This expansive heat will allow temperatures to soar into the upper 80s or 90s from the southern Great Lakes, mid-Mississippi Valley and Ohio Valley into the Northeast. In addition to the hot temperatures, dew points will also climb into the upper 60s and 70s for many areas, making it feel very humid. This will set the stage for heat index values, or what it feels like, to be around 100 degrees.
(FORECAST: Chicago | St. Louis | Detroit)
Low temperatures will also be very warm. Most areas east of the Mississippi River will not see temperatures drop below 70 degrees late this week. The exceptions will be parts of the northern Great Lakes, Upstate New York and northern New England, where lows in the 60s are expected.
New York City and Boston both last saw the mercury rise to 90 degrees on May 28, and it looks like the 90-degree mark may be within reach by Wednesday and Thursday.
(FORECAST: Boston | New York | Washington, D.C.)
However, there may be some relief at times in the northern tier due to disturbances that will bring the chance of showers and thunderstorms from the Midwest into the Northeast later this week.

Prolonged Southern Heat

This Week's Forecast

The trend of very warm temperatures will also continue in the South.
This comes after a very warm June in many locations in the South. The second warmest June on record was experienced at the New Orleans International Airport, with an average temperature of 84.2 degrees. Both Columbia, South Carolina, and Jackson, Mississippi, recorded their fourth warmest June with an average temperature of 83 degrees and 81.9 degrees, respectively. Atlanta also saw a top-ten warmest June, coming in sixth with an average temperature of 81 degrees.
(MORE: Hottest Temperatures Ever Recorded in All 50 States)
Temperatures will likely return to closer to average early this week, as the chance for showers and thunderstorms increases.
However, it looks like the very hot, sizzling temperatures will return later in the week. Highs will be in the upper 90s to lower 100s for many locations across the South. When dew points ranging from the mid-60s to the mid-70s are factored in, heat index values will easily soar into the 100s.
(FORECAST: Nashville | Raleigh | Atlanta)
Low temperatures across much of the region will also only dip into the mid and upper 70s, providing no relief at night. This heat will also last for a stretch of at least a few days, resulting in a prolonged period of very hot and humid, as well as potentially dangerous, conditions.
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