For the third straight morning, Hoosiers woke up to more of a September-like feel. Early-morning lows fell to near 50-degrees in Montgomery and Henry counties. Crawfordsville posted a 50° low following yesterday’s 49°, while New Castle dipped to 51°.
So what is behind the cool weather? The combination of a dip in the jet stream and a shift in surface winds to the northeast delivers the very mild weather for early August. Dew points that remain well below 60-degrees (dry air) will allow the air to cool through the night, and under clear skies we will easily fall in most outlying areas into the 50s for the fourth straight morning.
Scanning weather records, the opening to August is the coolest in 29 years (since 1992) with an overall average temperature of 69.8°. That ranks 18th or among the coolest 18% on record.
HEAT ON THE HORIZON
The lack of heat in the central U.S. and to the eastern seaboard is impressive! The nearest 90-degree temperature was in western South Dakota Tuesday. The large dip in the Jet stream opened up the flow of cooler and drier air but only for the time being.
A new pattern is set to emerge, and as the transformation of a coast-to-coast hot dome gets underway, our temperatures will start to rise. High temperatures will climb to as much as 7° above normal on Sunday, perhaps elevating to the hottest of the year, and the overall outlook will support a high likelihood of above normal temperatures through mid-August for much of the eastern U.S.
To-date, Summer 2021 has had an even split in above normal versus below normal temperatures. The upcoming hot spell could certainly sway summer’s average. Each of the past three summer’s have averaged above normal.