User:Robertson713325/sandbox

Weather

High pressure up traps heat near the ground, forming a heat wave

The temperatures soared to record highs in July with the hottest weather occurring from July 12 to July 16. The high of 106 °F (41 °C) on July 13 was the second warmest July temperature (warmest being 110 °F (43 °C) set on July 23, 1934) since records began at Chicago Midway International Airport in 1928. Nighttime low temperatures were unusually high — in the upper 70s and lower 80s °F (about 26 °C). At the peak of the heat wave, as was the case in the summer of 1988, and possibly 1977, Madison, Wisconsin probably would have broken its all-time maximum temperature record of 107 °F (42 °C) had the reporting station been in the same location as it was during the 1930s.

Plotted observed temperatures from O'Hare International Airport. Red Lines are daily max temperatures, Blue Lines are daily minimum temperatures, and the Black Line is the July 1960-2016 mean temperature.

The humidity made a large difference for the heat in this heat wave when compared to the majority of those of the 1930s, 1988, 1976–78 and 1954–56, which were powered by extremely hot, dry, bare soil and/or air masses which had originated in the desert Southwest. Each of the above-mentioned years' summers did have high-humidity heat waves as well, although 1988 was a possible exception in some areas. Moisture from previous rains and transpiration by plants drove up the humidity to record levels and the moist humid air mass originated over Iowa previous to and during the early stages of the heat wave. Numerous stations in Iowa, Wisconsin, Illinois and elsewhere reported record dew point temperatures above 80 °F (27 °C) with a peak at 90 °F (32 °C) with an air temperature of 104 °F (40 °C) making for a 148 °F (64 °C) heat index reported from at least one station in Wisconsin (Appleton) at 17.00 CDT (22.00Z) on the afternoon of 14 July 1995, a probable record for the Western Hemisphere; this added to the heat to cause heat indices above 130 °F (54 °C) in Iowa and southern Wisconsin on several days of the heat wave as the sun bore down from a cloudless sky and evaporated even more water seven days in a row.

A few days after, the heat moved to the east, with temperatures in Pittsburgh, Pennsylvania reaching 100 °F (38 °C) and in Danbury, Connecticut, 106 °F (41 °C) which is Connecticut's highest recorded temperature.

Dew point records are not as widely kept as those of temperature, however the dew points during the heat wave were at or near national and continental records.

The Analysis

This is an image of plotted 500mb heights and 2m temperatures for the United States on 1995-07-13 20:00:00Z

The heat wave was caused by a large High pressure system that traversed across the midwest United States. This system was consistently producing temperatures in the 90's ^F during the day with temperatures still reaching as high as the 80s at night, of which is abnormal for midwest summer months.

The two main reanalyses looked at were the MERRA-2 and the ERAI. The system proceeded to move eastward over the next couple of days dying out near the 18th completely.