Denton County residents enjoyed a break from the heat on Sunday courtesy of a very unusual weather pattern.
A low-pressure system bringing much cooler temperatures and light rain moved into Texas from the east, the opposite direction from where most storm systems emanate.
Along with rain showers most of the day, a record low maximum temperature of 81 degrees was set Sunday at DFW Airport just after midnight, tying the record set in 1989.
Saturday’s high temperature was a not-so-pleasant 100.
According to meteorologist Brad Barton, strong upper-level winds are vital to steering various weather systems across North America generally from west to east.
In colder months, they are most active as they steer between intense cold highs and intense warm low pressure areas, forming deep north-to-south meanders in the pattern.
In the heat of summer, the strongest jet stream winds recede north into Canada, leaving the lower 48, Mexico and the Caribbean with broad, light upper-level wind patterns shaped by massive high-pressure heat domes such as the one in Nevada two weeks ago.
As that western high receded to the southwest, it formed an area of lower pressure in the east, permitting deeper penetration of storms coming off the semi-permanent Hudson vortex.
A Hudson storm dragged unusually high pressure down from the Maritime provinces into New England, which helped push the east coast storm system southwest, the same way it was already being drawn by the receding western high.
“Highs and lows expand and contract all the time, but without the stronger steering currents of the colder months to keep them organized in the familiar west-to-east pattern, weather systems can occasionally back up on us, this time to our benefit,” said Barton.
The rainy, cooler weather is expected to remain in our area through at least Wednesday.