Recently, Bartlesville Oklahoma went from a low temperature of -28 F on the 10th of February to a high temperature of 82 F on the 17th. This is a remarkable 110 degree change on the seventh day. Can any site in Iowa compete with this? The featured chart presents an IEM computation of historical climate data in Iowa and the largest value is 106 degree change on the 9th day. This happened during a remarkable period in February 1930 for Webster City after a low temperature of -34 was followed by highs in the 60s and then 72 on the 24th. Please note that the number for the 0th day is simply the difference between the high and low temperature (Tripoli 18 Jan 1996).

Voting:
Good = 13
Bad = 3

Tags:   climate   high   low   extreme  

The featured chart presents the daily computed correlation between the high and low temperature. Higher values imply a closer relationship between changes in highs and lows. For example, a cold low temperature would typically imply a cold high temperature for that day. There is a clear annual signal shown, but the question is what causes it... One reason may be that the increase in moisture and warming soil temperatures cause overnight lows to moderate and not vary as much. Another potential explanation is that air masses dominate in the winter season and perhaps that causes highs and lows to be more regular. What do you think? Feel free to comment on this via facebook!

Voting:
Good = 20
Bad = 7

Tags:   climate   high   low  

The featured chart presents the average temperature departure from average after a day that has either a high temperature two standard deviations (two sigma) warmer than average or a low temperature two sigma colder than average. You could think of this plot as examining how persistent really warm or cold days are. The plot is divided up by seasons showing how warm temperatures in the summer time tend to stick around longer than in the other seasons. Warm weather in the winter time is not as fleeting as one might have expected. Cold weather tends to stick around slightly more in the winter time than other seasons. Very cold air is set to arrive this weekend and stick around for most of next week.

Voting:
Good = 20
Bad = 7

Tags:   climate   high   low   extreme  

Yesterday's feature looked at the warmest spots in the state and today's feature shows the favored spots in the state with the lowest daily minimum temperature. This plot nicely shows some topographic effects that even occur in a flat state like Iowa. Northeast Iowa is the relatively cool, but the observation sites in the Mississippi River valley are sheltered some by the warm water during the fall season. Northwest Iowa is another location and it extends down into westcentral Iowa along the Nishnabotna Valley.

Voting:
Good = 23
Bad = 6

Tags:   low  

The featured chart presents the number of years since the record high or low temperature was set for Ames. Ties were not considered. Ames went another meteorological summer without setting a record high temperature. One has to go back to 1988 to find the last record high for Ames during June, July, and August. For July, the youngest record for high temperature was back in 1955! No records are in the forecast for this week.

Voting:
Good = 18
Bad = 3

Tags:   climate   high   low  

Roughly a week ago, some places in Iowa were setting records for warmest temperatures and then with the most recent storm, record rainfall. The featured chart looks at the frequency of having a record temperature around the days of having a record daily rainfall based on data for Ames. You can see how record maximum high temperatures frequently occur before a record rainfall as very warm air masses would imply stronger fronts, which should help produce higher rainfall amounts (as what recently happened). Record minimum highs (cold) also appear to be a common after a record rainfall. The climatology for any of the days shown on the chart would be one record.

Voting:
Good = 29
Bad = 10

Tags:   climate   high   low  

The featured graph displays the difference in climatological average high and low temperature for Ames between the first and the last of the month. Positive values would indicate that the trend for the month is warming. The ten degrees of warming shown for February would feel nice right about now with bitterly cold air once again settled into the state. Some warmer weather is in the immediate forecast, but with the chance of more winter storms.

Voting:
Good = 20
Bad = 6

Tags:   high   low  

The end of 2009 also brought the end of the first decade of the 21^st century. The featured graph looks at the number of days per decade our current set of daily high and low temperature records consists of. Roughly 1/3 of our current daily high temperature records occurred during the 1930s and most of our daily low temperature records occurred before the 1950s.

Voting:
Good = 15
Bad = 7

Tags:   climate   high   low  

The featured chart plots the number of days per year that experienced a high or low temperature exceeding two standard deviations from average for Ames. For example, some of last week's cool high temperatures in the 40s were two sigma below average. This chart is an attempt to quantify how "extreme" a given year was. In general, the highest values were prior to 1940 which is probably a reflection of the data quality for that period, although the very hot years in the 1930s show up nicely in this chart.

Voting:
Good = 14
Bad = 5

Tags:   high   low  

The featured chart is the percentage of days per month that experience either high or low temperatures at least 1 degree warmer than the previous day. April has the largest value for high temperature, but is just a mere few percentage points larger than October which only equates to approximately 1 more day per month. This chart would imply that climatology does not have a strong influence on actually seeing our day to day temperatures warm. Day to day temperatures are more strongly influenced by the passage of air masses.

Voting:
Good = 22
Bad = 18

Tags:   climate   high   low