After what seems like a prolonged spell of rather humid conditions across the lower Missouri River Valley, the weather pattern shifted over the weekend to allow for a prolonged period of pleasantly dry and comfortable conditions. These cool temperatures are due in part to a pattern favorable for allowing cool Canadian air masses to sink southward into the central United States behind numerous weak disturbances and reinforcing cool fronts. As you can see from the animated image below, a pattern which often looks like a backwards "S" will feature a large trough of low pressure across the Great Lakes, likely resulting in very cool, showery, and grey days. Areas along the Rockies experience very warm temperatures under a ridge of high pressure. However, locations stuck in between these two air masses, such as Missouri and Kansas, often experience the most pleasant weather with near to slightly below average high temperatures, mostly sunny skies, and often times much drier and more comfortable air.
|Animated Upper Level Weather Pattern (July 16-July 19)|
While high temperatures ran some 15 degrees below their seasonal normals, low temperatures on the other hand were so low that they broke records in many locations. Clear skies and light winds made conditions perfect for radiational cooling. This is a process where without clouds or strong winds, the ground can more easily release its heat back toward space during nighttime hours, allowing air temperatures to cool much lower than normal. On a cloudy night, this release of heat from the ground can be captured by overhead clouds and reflected back towards the earth, keeping temperatures warmer. Due to their lower valley elevations relative to other locations, St. Joseph, Lawrence, and Olathe New Century Airports will often experience overnight low temperatures much cooler than their surroundings.
Thus, with cooler than normal daytime temperatures and dry air in place, nighttime temperatures plummeted towards and even below the all-time records though Sunday morning. Here is a listing of normal temperatures and record temperatures through the weekend for Kansas City and St. Joseph.
|Kansas City (*R denotes Record)|
|Day||Observed High||Observed Low||Normal Temperature||Record High||Record Low|
|July 17||76 (4th coldest)||55R||89 / 68||108 in 1954||59 in 1967|
|July 18||78 (4th coldest)||56R||89 / 68||111 in 1954||58 in 1984|
|July 19||81(Top 15 Coldest)||54R||89 / 68||109 in 1934||59 in 1947|
|July 20||62||89 / 69||109 in 1934||60 in 1971|
|St. Joseph (*R denotes Record)|
||Observed Low||Normal Temperature
||77(Record Cold High)||53R||90 / 68||106 in 1954||55 in 1976|
||78 (3rd Coldest)||53R||90 / 68||106 in 1934||54 in 1911|
||82||54R||90 / 68||108 in 1934||55 in 1947|
||63||90 / 68||108 in 1934||50 in 1971|
Is it that unusual to break three records in a row?
Research provided to us by one of our media partners, WDAF FOX-4 in Kansas City, revealed that we have indeed broken record lows on three consecutive days here in Kansas City. In total, since 1888 there have been 8 instances where the low temperatures has been broken in sequence. These dates are:
|Dates: 3 Records in a Row|
|October 27-30, 1925|
|September 2-5, 1974|
|December 18-20, 1983|
|December 21-23, 1989|
|November 1-4, 1991|
|July 27-29, 1994|
|October 7-9, 2000|
|August 10-12, 2004|
|July 17-19, 2009|