Pattern Change: End in Sight to Southeast Misery; Midwest, Northeast to Turn Even Cooler

Linda Lam
Published: June 23,2015
The uncomfortable and record-breaking heat will persist for much of this week in the Southeast, but have a little patience as there is hope ahead.
A change in the pattern will finally bring some much-needed relief from the ongoing heat wave. Meanwhile, the Midwest and Northeast will continue to find relatively cool conditions after a short tease of summer heat.
Late this week the jet stream takes a sharp southward dive over the East, squashing the eastern half of the area of high pressure that has set up over the southern U.S. This will in turn squash the heat wave, leading to cooler conditions.

At the same time as the southward dip in the jet stream slides over the East, the jet stream will lift northward over the Northwest, bringing record heat to that region.
(MORE: Western Heat Wave May Break June Records)
Temperatures will cool closer to average in the South and Mid-Atlantic while falling up to 15 degrees below average in parts of the Northeast and Midwest starting Friday.

Southeast Relief

Much of the Southeast has been baking under a strong upper-level ridge of high pressure for more than a week. This has brought a stretch of hazy, hot and humid days.
This expansive area of high pressure will continue to encompass much of the southern half of the U.S., allowing the early season heat wave to persist for much of this week before a long-awaited change takes place.
(MORE: Sweltering Stretch of Record Heat in the Southeast)
Heading into this weekend, high pressure will weaken as that southward dip in the jet stream moves into the East and a cold front moves into the Southeast. This will allow temperatures to return to closer to where they are expected to be for this time of year – much more comfortable than the last week or so.
Instead of highs 5 to 15 degrees warmer than average with temperatures soaring into the mid and upper 90s, highs will be close to average with temperatures topping out in the 80s and lower 90s.
(FORECAST: Nashville | Charlotte, North Carolina | Birmingham, Alabama)

Forecast Highs in the Southeast

Low temperatures will also be slightly cooler, with temperatures dropping back into the 60s.
Atlanta has reached 90 degrees 9 out of the last 10 days with the mercury rising as high as 95 degrees. This weekend highs are expected to be in the mid 80s, which will undoubtedly feel refreshing.
Raleigh, North Carolina has also seen a very warm June with the average temperature, which factors in both high and low temperatures, more than 3 degrees above average. The thermometer even reached 100 degrees on June 16, setting a new record for the date. Air conditioners may get a little break this weekend with highs near 80 degrees.
(MAPS: 10-Day Forecast)
Charleston, South Carolina experienced ten consecutive day of temperatures reaching the mid 90s. Numerous record warm low temperatures have been set as well over the last few days as well. By this weekend highs will be in the 80s or low 90s and lows will drop back into the lower 70s.
This pattern will also increase the chance of thunderstorms across the Southeast, after a relatively dry stretch for many, due to a moist southwest flow and a weak front stalling near the region.

Cool Northeast, Midwest

Meanwhile, much of the Northeast and Midwest have not seen a long stretch of real summer heat – at least, not in summer. The end of spring was hot; in fact, it was the hottest May on record in the Northeast. In June, though, there have been a few brief periods of hot conditions, reminders of summer, but most locations have seen temperatures close to or slightly below average for this month.
The Mid-Atlantic is one of the areas that have seen a few rounds of heat, including Philadelphia which tied their record high on June 12 of 95 degrees.

Forecast Highs

There was a quick shot of heat and humidity in the Northeast on Tuesday. Temperatures reached the mid 90s in Washington, D.C.,  Atlantic City , Philadephia, and Baltimore .
This taste of summer, however, was short lived as a cold front is pushing through the Northeast. Then late week and into the weekend, as the jet stream dips southward over the eastern U.S., cool conditions will be locked in as high temperatures will be up to 15 degrees below average.
(MAPS: Weekly Planner)
New York climbed to 89 degrees on Tuesday, but then temperatures will drop into the 70s late week, with highs possibly only reaching the 60s this weekend.
Boston has been fairly cool for June with the average high temperature more than 2.5 degrees cooler than average. Highs have only reached 80 degrees 5 times this June -- the average number of 80 degrees days in June is 11. Below-average temperatures are expected to dominate beginning late this week with highs only in the 60s late this week and into early next week, average highs are near 80 degrees for the end of June.
The National Weather Service weather forecast office in Boston noted in their forecast discussion that "overall this is an atypical pattern for the beginning of summer. Looks just awful. Overall unseasonable with onshore east/northeast winds. Periods of wet weather at times."
(FORECAST: Newark, New Jersey | Hartford, Connecticut | Indianapolis)
Temperatures have also been cooler than average in the Midwest, including Chicago where highs beginning late week will only be in the low 70s (average highs should be in the mid 80s) and lows will even drop into the 50s.
Cool conditions have also been prevalent in Marquette, Michigan where the average temperature for June is more than 2 degrees below average. That trend is likely to continue to end the month as highs in the 60s and low 70s are expected (average high is in the mid 70s).
A noticeable temperature drop will take place in St. Louis as well. Highs will go from the mid 90s midweek to near 80 degrees late week, along with noticeably lower humidity. A similar scenario is expected in Kansas City, where temperatures will struggle to reach 80 degrees late this week – a pleasant change to end June.
MORE: Summer Solstice (PHOTOS)