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 forecast holds a great deal of optimism for a streak of at least a week of above freezing daily high temperatures this would follow a period of 12 days with highs at or below (AOB) freezing. The featured chart looks at the longest streaks of having daily highs AOB freezing and then having them above freezing. There are two dots presented for each year denoting the longest streak on each side of the regime change. One of the interesting outliers in this plot is what happened last spring. After a period of 37 days below freezing, temperatures warmed on 2 March and we had 265 straight days of high temperatures above freezing. So the longest streak of 37 days was followed by a streak of 265 days. The crosses represent the longest second part of the streak and what the streak was below freezing before that streak. Kind of confusing, so please comment if this does not make any sense!

Voting:
Good = 32
Bad = 15

Tags:   high   freeze  

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  

With the past two mornings being frosty ones in parts of Iowa, one may wish to find the warmest spot in Iowa. The featured image presents the frequency of a climate location in the state having the warmest temperature for any given day. The plot shows three favored locations: far southeast Iowa, southwest Iowa, or along the Missouri River near Sioux City. The least frequent being far northeast Iowa.

Voting:
Good = 31
Bad = 9

Tags:   high  

Yesterday, Los Angeles, California set their all time record high temperature of 113! This may seem weird for the calendar showing the near end of September. The featured chart shows the yearly maximum temperature for Ames and the day of the year that high was reported (ties are included). The distribution of that high temperature and day of year is presented as well. For the most part, the warmest temperature occurs in July and it is somewhere in the mid 90s. The color coding of the dots shows if that year had above or below normal precipitation. It makes sense that most of the warmest numbers occured during relatively drier years.

Voting:
Good = 19
Bad = 8

Tags:   high  

After having high temperatures in the 50s on Sunday, warm air rushed the state on Monday pushing highs well into the 80s. For some places like Ames, the jump in high temperature was over 30 degrees in just one day! The featured chart presents the largest one day high temperature rise and drop along with the number of occurences of a 30+ degree change based on data for Ames. You can see in the summertime that these large of changes do not occur and are rare for September.

Voting:
Good = 36
Bad = 8

Tags:   high   2010  

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 chart presents the earliest and latest occurrence of a temperature threshold after the first of the year. Many parts of the state have yet to reach 40 degrees, which is approaching a record as shown on the chart for Ames. It is interesting to note how the "latest" line flattens out around 32 F, which basically shows the influence of a deep snowpack in February and early March (much like what is happening this year). This chart also shows that some years, by this date, we have experienced temperatures above 70 degrees. Imagine what that must feel like!

Voting:
Good = 30
Bad = 8

Tags:   climate   high  

Ames has not seen a temperature at or above 40 degrees since the first of December (83 days). The featured graph looks at the longest periods of consecutive days above or below a certain high temperature threshold for Ames. The record for consecutive days below 40 appear is around 92, so we'll have to make it to March to set that record. The plot is truncated at 1000 days, but values at the extremes go well beyond 1000.

Voting:
Good = 27
Bad = 10

Tags:   climate   high  

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  

Building off of yesterday's feature, today's feature looks at the mean amount of rainfall in three different 7 day periods for a given high temperature in June for all sites in Iowa. For a given day, these 7 day periods are the 7 days prior to the high temperature, the 7 days centered on the high temperature, and the 7 days after. The plot indicates an interesting regime change from when we have highs in the 70s versus highs in the 90s. Notice how in the 70s, the centered and after lines mostly track, while in the 90s the prior and centered lines track. One interuptation would be that when temperatures warm up, more rainfall comes in the forecast and effectively knocks temperatures back down into what is shown in the 70s with more precipitation in the prior period. The overall decrease in precipitation for increasing temperatures is also important (the sun can more effectively warm the ground when it is drier [less precip] ). Rain is in the forecast for this weekend with some strong storms possible.

Voting:
Good = 18
Bad = 12

Tags:   climate   high   precip  

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  

The featured graph displays the frequency of having a high temperature less than 40 and a high greater than 70. High temperatures on Saturday were in the 30s, which was extremely rare for this time of year. Having highs in the 70s are rare for this time of year as well, but the chances are increasing each day! The forecast was highs approaching 70 by mid week.

Voting:
Good = 26
Bad = 10

Tags:   high