Beginning of Summer's First Full Week Won't Feel Summerlike in the East

Brian Donegan
Published: June 25,2017
Summer officially arrived last Wednesday, but residents of the Midwest and East are enjoying a brief break from heat and humidity to start this week.
The jet stream has reconfigured into an upper-level trough, or southward dip, over the eastern states while an upper-level ridge of high pressure, or northward bulge, remains parked over the West.

Forecast Upper-Level Pattern for Tuesday

This weather pattern change is resulting in a period of below-average temperatures from the Midwest to the East, while scorching heat continues to sear portions of the western states, where all-time record highs were tied last week.
(RECAP: Extreme Heat Seared the Southwest; Las Vegas Tied All-Time Record High)

Midwest Forecast

The early summer atmospheric air conditioner has already been kicked on in portions of the Midwest and the cooler air is spreading east and south.
Parts of the northern Plains and Upper Midwest dipped into the upper 30s and low 40s on Sunday morning. Aberdeen, South Dakota, even tied its daily record low of 41 degrees.

Forecast Morning Lows

Locations along the nation's northern tier from the Dakotas eastward to Upper Michigan will see 40s for lows on Monday morning. Bismarck, North Dakota (42 degrees), and International Falls, Minnesota (39 degrees), could flirt with their daily record lows (record to beat is shown).
Urban heat island locations shouldn't drop below the mid-50s, however, and some bigger cities could actually hold in the lower 60s. Additionally, areas along the shores of the Great Lakes will be milder than inland locations due to influences from the warmer waters.
(MORE: Urban Heat Islands: Why Cities are Warmer Than Rural Areas)
High and low temperatures should recover to late-June averages by Tuesday or Wednesday of this week – good news for those who want summer to live up to its warm reputation.

East and South Forecast

The cooler-than-average temperatures will be enjoyed in the eastern states into midweek.
Temperatures won't be quite as cool as in the Midwest, but readings as much as 10 degrees below average are possible, especially in the interior Northeast.
Highs will be in the 70s across much of the Ohio Valley and mid-Atlantic early week, with mid- to upper 60s in parts of the Appalachians northward into upstate New York.
(MORE: Temperature Outlook Through Late Summer)

Forecast Highs

The air will be dry, so temperatures will drop quickly after sunset during this upcoming cooldown. It'll also lead to below-average overnight lows.
Low temperatures will be up to 10 degrees cooler than average Monday through Wednesday mornings in the East, with the farthest-below-average readings likely from the Ohio Valley to western portions of Pennsylvania and New York.
This translates to lows in the 50s in most of the Northeast and Ohio Valley, but low to mid-60s are expected in the mid-Atlantic, especially in the warmer metropolitan areas due to the urban heat island effect.
(MAPS: Average Highs and Lows)

Forecast Morning Lows

Even the Southeast will enjoy below-average temperatures and lower humidity early this week thanks to the cold front passage. Although highs will remain in the 80s, the drier air should make things feel much more pleasant for a couple of days.
MORE: Summer in Every State

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