The featured chart displays the yearly net total of days above average for low temperature (negative values would mean that more days were below average than above). So far in 2009, Ames has seen 50 more days below average for low temperature. This is roughly the largest negative value we have seen in the last 40 years, granted there are 2.5 months left to this year yet.

Voting:
Good = 34
Bad = 15

Tags:   lows  

The past week or so has seen high temperatures not vary much for Ames with the range being a mere 3 degrees (78-81). The featured chart looks at the minimum 7 day temperature range for all days of the year. In general, the lowest values are in the summer time when strong temperature fronts are not common. The spikes during the spring and fall months are when we often experience air mass changes via strong fronts.

Voting:
Good = 8
Bad = 12

Tags:   persistence   highs   lows  

Last Friday, we were experiencing low temperatures around our average high for the date. Today, we are on the opposite end with high temperatures near our average lows. The featured chart looks at frequency of having the high temperature below the average low. As with Friday's chart, there is a period in the summertime where this has never occured for Ames. Our actual weather is expected to warm up this weekend!

Voting:
Good = 22
Bad = 3

Tags:   highs   lows  

In some locations, low temperatures on Thursday were warmer than the average high temperature for the date. The featured chart looks into the frequency of this occurance with the bars representing the number of years that this has occurred for Ames. The red line is the record daily maximum low temperature and the black line is the daily average high temperature. Notice that during the summer season, the black line is always higher. In fact, the period of 9 May to 29 Sep has never seen a low temperature greater than the average high for Ames!

Voting:
Good = 35
Bad = 19

Tags:   highs   lows  

Keeping with the recent features, today's feature is a chart of the hour during which the low temperature occurs. Low temperatures tend to occur just after sunrise when net radiation finally becomes positive (downward). This chart shows this trend with lows happening earlier in the morning during the summer. You can also see a secondary maximum around 11 PM, which is often the case when clear skies at night follow a cloudy day allowing temperatures to drop rapidly below levels during the cloudy morning.

Voting:
Good = 23
Bad = 12

Tags:   climate   lows