Weather Pattern Does a Flip in the East

The weather pattern in the upper atmosphere from around the Mississippi River eastward is doing a complete reversal from what we saw last week.

The big dome of high pressure that brought sweltering temperatures from the Upper Midwest to the Great Lakes and Northeast for many days has been replaced by a southward dip in the upper-level wind flow. In meteorological terms, the hot "ridge" of high pressure is being replaced by a "trough".

With all of this going on in the atmosphere above us, what does it mean for where we live at the surface? We have good news and bad news. Let's start with the good news first.

Good News: Temperatures More Comfortable

When we see a trough in the upper atmosphere, that usually means cooler temperatures.

That's exactly what we will see over the next several days with temperatures generally hovering near or slightly below late-July averages from the Upper Midwest to the Great Lakes, Ohio Valley and Northeast.

From Minneapolis to Chicago and Boston, this means highs will mostly be in the 70s and 80s into at least Thursday. Temperatures will also stay at a reasonable level for this time of year in the Southeast with highs peaking in the 80s in most locations, though a few places may touch the low 90s.

(HIGHS: Tue | Wed | Thu)

For parts of the Midwest and interior Northeast, low temperatures will cool off nicely as well. This will especially be true by mid-week and on through Friday as a second push of cooler air moves into the region. Parts of northern Wisconsin, northern Michigan and northern New England could dip into the upper 40s on a few mornings later this week.

The I-95 Northeast urban corridor from New York City southward will finally feel relief at night, with morning lows in the 60s likely by Thursday morning.  This will bring Philadelphia's now record-breaking streak of 29 consecutive nights at or above 70 degrees to an end.

(MORE: Your Local Forecast)

Bad News: Stormy at Times

Embedded in the trough that is taking over the eastern third of the nation will be impulses diving south and eastward periodically.

These impulses of energy will provide lift in the atmosphere to help spark scattered showers and thunderstorms each day.

Rain chances will exist on one or more days in portions of the Mississippi Valley, Great Lakes, Ohio Valley, Southeast, Middle Atlantic and Northeast regions. That said, not every location will see rain each day.

Some of the storms could produce locally heavy rainfall, flash flooding and gusty winds.

For a look at where storms chances will be the greatest each day, you can click on the day-by-day forecast map links below.

(RAIN THREAT: Tue | Wed | Thu | Fri | Sat | Sun)

PHOTOS: Middle July 2013 Heat Wave in the East