Past IEM Features tagged: records
A daily record low temperature for Waterloo has been set this morning, so it is good timing to look at the yearly frequency of setting a new high and low record temperature. The featured chart presents this metric by computing the number of new records set each year from the beginning of the period of record. The black line represents a sort of theoretical expected frequency based on the number of years that have passed. During the beginning of the record, there are much fewer years of history so it is a bit 'easier' to set records. Years that exceed this expectation are colored differently. For recent years, the warm weather of 2012 certainly stands out as an anomaly.
The Waterloo Airport reported a low temperature of -19 degrees this morning, which beat the previous record by 13 degrees! The featured chart presents the amount a newly set daily record temperature beat the previous record-to-date for that day for Waterloo. A thirteen degree beat for low temperature was the largest departure since 5 Dec 2005. Some of the extreme beats are labelled on this chart and you'll notice most of the dates are in the winter and spring months. Temperatures are more constrained in the summer time thanks to soil temperatures and atmospheric humidity, so it is much more difficult to get large beats of records during those months.
Tags: highs lows records
On 2 May, the high temperature for Des Moines set a record for coldest high temperature for that date. It was the first cold record (minimum high or low) record set at the site since early 2010! Des Moines had a streak of 55 straight hot records being set or tied without a cold record. This is easily the largest streak experienced at the site since 1900. The featured chart presents the largest hot and cold streaks of records. It is remarkable to see a period of three years without a single daily cold record being set. There is no other period comparable to this.
After setting a record high temperature on Monday of 69 degrees, the high on Wednesday for Des Moines was only 46 degrees (still above average though) making for a 23 degree change over the two days. Is this typical? The featured chart presents the monthly distribution of two day high temperature change after a day of setting or tieing the record high. While actual data goes back to the late 1800s, the period up until 1930 was used as a "warm up" for this chart. The box plots used on the chart show the median (red line), 25th and 75th percentiles (box bounds) and the whiskers represent the 2nd and 98th percentiles. For December, the current change of 23 degrees is only slightly lower than the long term median, so it is about what we would expect. Postive values on this chart would indicate the day two temperature was warmer than the record setting temperature. This situation appears to be the most common in July as record warmth tends to provide conditions for more record warmth. In the winter season, record warmth is from a displaced air mass that is often replaced by a colder air mass with the passage of a storm system.
Tags: records highs