From Polar Blast to Sizzling Northwest: 5 Unusual Features of the Mid-July Weather Pattern

Is This Really Mid-July?

Are we really heading into the heart of summer? That's the question most of the country will be asking through the week, since this weather pattern is a bit unusual for mid-July.

A strong upper-atmospheric trough will dig into the Midwest and an upper-atmospheric ridge will be amplified in the Northwest. This pattern is more like fall than summer!

(MORE: What's a Trough? | What's a Ridge?)

Temperature records will be broken across much of the country and weather conditions more common in early fall will be making a guest appearance.

So let's take a look at the five most unusual features of this weather pattern.

NEXT: Feeling Like Fall

1. Feeling More Like Fall

A strong upper-level trough will bring below-average temperatures to much of the East and Midwest through mid-week. This upper-level trough is unusually strong for mid-July, which is the heart of summer.

Record low temperatures are possible from the Ohio Valley to the South, as well as into the Plains. Record cool high temperatures are also possible for much of the Midwest and Plains.

At least 30 cities will threaten daily record lows Thursday morning, according to the current forecast. Included in those potential records in the Midwest and Northeast are:

- Cincinnati (current record: 51)
- Pittsburgh (current record: 52)
- Omaha (current record: 53)

(FORECAST MORNING LOWS MAPS: Thursday) 

Many people may need to put away shorts and bring out their jackets, as there will be a chill in the air. In fact, it will feel like late September/early October for cities such as Chicago and Marquette, Michigan. Some daytime highs may struggle to reach 60 degrees in parts of the northern Great Lakes. Parts of the Plains and Ohio Valley will be no warmer than the 70s through much of this week.

(FORECAST HIGHS MAPS: Wednesday | Thursday)

NEXT: Heat Wave

2. Sizzling In The Northwest

The upper-atmospheric trough that will dig into the East will amplify the upper-atmospheric ridge in the West. This will bring higher temperatures to the Pacific Northwest, where temperatures will rise 10 to 20 degrees above average.

Seattle will continue to see above-average temperatures, with highs in the mid to upper 80s through mid-week. As of July 12, the city is in second place for its warmest July, with temperatures averaging over 5 degrees above-average. 

Heat advisories are posted for parts of Washington, Oregon and California. Record highs are possible as well across the region. Triple-digit heat will sear parts of from interior Washington state to California's Central Valley. 

(FORECAST: Seattle | Portland | Boise)

A gradual easing of the heat is expected by later this week.

NEXT: Rain In Drought Areas

3. Drought Relief On The Way

You probably can't draw up a better setup for soaking rain in a drought-starved area in mid-summer than this week's setup.

However, with this rain also comes the risk of flash flooding. A widespread area of 2 to 3 inches is likely with over 4 inches possible.

This rainfall is the result of a cold front pushing unusually far south and becoming stationary, while a bubble of high pressure retrogrades (that is, moves westward) into the Great Basin. This will allow for northwest winds to develop in the upper atmosphere, sending disturbances southeast across the area. Upslope easterly winds near ground level will increase midweek, while moisture from the Gulf of Mexico is drawn northward.

This setup will allow for the possibility of a multi-day heavy rain event from southern Colorado into the Texas. Also, the risk of flooding rainfall will rise in parts of the Tennessee Valley not in drought, particularly later this week.

(FORECAST: Albuquerque | Wichita Falls | Dallas)

NEXT: Southern Cold Front

4. Cold Front In The South

It’s not every July that a cold front makes it into the South, but this seems to be the case this week. The unusually strong cold front for mid-July will push into the Deep South midweek. 

The consequences of this unseasonably strong front will be an enhanced risk of thunderstorms, as well as cooler and drier air.

Ahead of the cold front, there will be plenty of moisture, which will bring locally heavy rain. The risk of severe thunderstorms will be higher as well, perhaps more similar to late spring or early summer.

However, behind the front conditions will be much more comfortable. Dew points will only be in the 50s from the Tennessee Valley into parts of the Deep South by Wednesday into Thursday. The typical mugginess of summer will be gone, at least for a couple of days.

Along with that drier air, daily record lows will be threatened in parts of the South into the upcoming weekend. Among the southern cities flirting with record lows are:

- Little Rock, Arkansas (daily records in the low 60s)
- Oklahoma City (daily records in the low 60s)
- Dallas (daily records in the upper 60s) 

Morning lows will plunge into the 50s in much of the southern Appalachians, with a few upper 40s possible in the high mountain valleys. Keep this in mind if you have outdoor plans this week.

(FORECAST MORNING LOWS MAPS: Thursday | Friday) 

Highs in the latter half of the week may struggle to rise out of the 70s in places like Oklahoma City, Little Rock, Memphis and Nashville, not only due to the passage of the cold front, but also due to a chance of soaking rainfall from thunderstorm clusters. 

Dating to 1875, only 52 Julys have had at least a single day when highs failed to rise out of the 70s in Memphis. The record number of such July days in Memphis is five, last occurring in 1924. Memphis may see several of these days this week. 

(FORECAST HIGHS MAPS: Wednesday | Thursday)

NEXT: Great Lakes Waterspouts

5. Waterspout Threat For The Great Lakes

A major waterspout outbreak is possible in the Great Lakes this week. 

Waterspouts generally form when water temperatures are warm, the air is cold and winds are relatively light. As cold air moves over the warmer water of the Great Lakes, the large temperature difference can cause them to develop.

Waterspouts are more common in northern Michigan from August to October when the water temperatures are the warmest.

Water temperatures are still running below average for Lakes Superior and Michigan. Lake Superior has water temperatures ranging from the upper 30s to the lower 50s. Current water temperatures are in the 40s, 50s and 60s in Lakes Michigan and Huron, from the 40s (west) to low 70s central in Lake Erie and mainly in the 50s and 60s in Lake Ontario. 

Air temperatures will be dropping into the 60s and 70s for high temperatures midweek for much of the region.

MORE ON WEATHER.COM: Waterspouts Over The Great Lakes