Thanks to a slow moving storm system to our south, places like Lamoni (in Southern Iowa) experienced a cloudy and rainy day while locations farther north like Mason City saw the sun and warmer temperatures. The high temperature in Mason City was 9 degrees warmer than Lamoni. The featured chart looks at the frequency of Mason City having a warmer high temperature than Lamoni (north/south comparison) and also Dubuque having a warmer high than Sioux City (east/west comparison). In November, Mason City is warmer than Lamoni about 10% of the time (think of it as 3 days for the month). The chart shows an interesting annual signal and a probable change in the dominate spatial temperature structure between the summer and wintertime.

Voting:
Good = 18
Bad = 9

Tags:   highs  

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  

High temperatures soared on Monday to values above normal for this time of year. The featured chart looks at the largest stretch of consecutive days with the high temperature above average per year for Ames. So far for 2009, the best we did was 11 days. Our current streak stands at a mere one day with today expected to make it two. Rain and cooler temperatures are in the forecast, so the current streak will not last.

Voting:
Good = 17
Bad = 7

Tags:   highs  

After a high temperature of 82 on Sunday, Ames only got up to 64 on Monday which is almost a 20 degree cool off in high temperature. The featured chart looks at the monthly frequency of having a 20+ degree high temperature swing either up or down. In general, these events are somewhat rare with primary direction being a 20+ degree downward swing.

Voting:
Good = 19
Bad = 6

Tags:   highs  

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  

The featured graph is a simple plot of the number of days per year that Ames has observed a high temperature at or above 90 degrees. 2008 only saw a handful of days while two years in the 1930s experienced 60 days (dust bowl). While the forecast for this weekend is for warmer weather, we will have to wait a while yet before maybe seeing 90 degrees again.

Voting:
Good = 25
Bad = 7

Tags:   highs  

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 graph displays the frequency of rainfall observations a day after a given high temperature for Ames. The three lines are the frequency of given minimum precipitation thresholds. While there are a number of things going on to make this plot appear the way it does, it generally shows that the frequency of rainfall events increases as our temperature increases (more rainfall in the summer). The interesting detail is to note what happens when temperatures reach the 90s. Our chances of rainfall decrease as the temperature gets even warmer. One could speculate that when our temperatures get really warm, the air mass is often drier and soil moisture state is drier as well allowing more efficient warm ups. Rewording, having temperatures in the 90s for Ames is probably associated with a dry weather pattern.

Voting:
Good = 15
Bad = 6

Tags:   climate   precip   highs  

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  

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  

The featured chart is the yearly difference between the number of days with a high temperature above average versus below for Ames. Negative numbers represent having more days below average than above. 1932 has the largest positive value while 1993 the lowest. For our recent decade, 2008 was the only year with a considerable number of more days below average. The number thus far for 2009 is a mere -4. Our weather is expected to creep above average later this week.

Voting:
Good = 27
Bad = 4

Tags:   highs   yearly   climate  

Like yesterday's feature on snow pack, today's feature presents a similiar plot for high temperature. The plot summarizes the day to day change in high temperature based on 100 years of data from Ames. The green area represents when the next day high temperature is within 5 degrees of the previous high. The red area represents when the high temperature change is greater than 5 degrees and blue area less then negative five degrees. The white lines denote 25, 50, and 75 years. The plot indicates that our next day high temperature is within 5 degrees of the previous high roughly 50% of the time. An interesting note is to notice where the blue and red areas exceed the 25 and 75 thresholds. These are times of year marked by warming (springtime) and cooling (fall).

Voting:
Good = 23
Bad = 14

Tags:   climate   hightemp  

Last Friday, we featured the favored times of rainfall. Today we featured the favored times of day when the high temperature occurs. This plot has a number of interesting features including the increased chance of the high temperature coming at midnight during the winter season. This is often associated with air mass changes with a steady feed of colder air during the day. Another interesting feature is the shift of high temperature shown between Feb/Mar and Oct/Nov. This is due to the change of daylight savings time. The hourly time axis on the plot is in local (standard/daylight) time depending on the time of year.

Voting:
Good = 27
Bad = 7

Tags:   climate   highs