Past Features
This page lists out the IEM Daily Features for a month at a time. Features have been posted on most days since February 2002. List all feature titles.
Tue Jul 01, 2025
Cedar Rapids below half inch
01 Jul 2025 05:30 AM
Back on May 20th, the Cedar Rapids Airport reported just over an inch of precipitation. Since then, the highest total has only been 0.49 inches making for a streak of over 40 days below a half inch of precipitation. The featured chart looks into such streaks for the site by plotting the maximum consecutive days by day of the year (blue line). The red line plots consecutive days with no measurable precipitation and finally the bottom panel simply reports the daily maximum precipitation amounts. Sitting at a 40 day streak on the 1st of July is getting close to the maximum at 50 days, but the current stretch would have to extend into late August before exceeding this particularly pigeon-holed record statistic. Of course, such streaks are much easier to achieve during the cold season when daily precipitation amounts are much less.
Voting: Good - 14 Bad - 0
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01 Jul 2025 05:30 AM
Back on May 20th, the Cedar Rapids Airport reported just over an inch of precipitation. Since then, the highest total has only been 0.49 inches making for a streak of over 40 days below a half inch of precipitation. The featured chart looks into such streaks for the site by plotting the maximum consecutive days by day of the year (blue line). The red line plots consecutive days with no measurable precipitation and finally the bottom panel simply reports the daily maximum precipitation amounts. Sitting at a 40 day streak on the 1st of July is getting close to the maximum at 50 days, but the current stretch would have to extend into late August before exceeding this particularly pigeon-holed record statistic. Of course, such streaks are much easier to achieve during the cold season when daily precipitation amounts are much less.
Voting: Good - 14 Bad - 0
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Wed Jul 02, 2025
Corn's Doing Great
02 Jul 2025 05:30 AM
The weekly update from USDA NASS on Monday continued to indicate that the corn crop is in excellent shape for Iowa. The featured chart presents the weekly estimated percentage of the corn crop in either good or excellent condition for Iowa and Illinois. The yearly time series for each year back to 1986 is plotted with this year and the previous two years highlighted for comparison. The most recent 2025 value is only topped by about three other years on record for Iowa. The recent weather has been nearly ideal with plenty of heat units and frequent rainfall events, this was after a somewhat concerning start to June with a lack of warmth and sunshine.
Voting: Good - 14 Bad - 2
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02 Jul 2025 05:30 AM
The weekly update from USDA NASS on Monday continued to indicate that the corn crop is in excellent shape for Iowa. The featured chart presents the weekly estimated percentage of the corn crop in either good or excellent condition for Iowa and Illinois. The yearly time series for each year back to 1986 is plotted with this year and the previous two years highlighted for comparison. The most recent 2025 value is only topped by about three other years on record for Iowa. The recent weather has been nearly ideal with plenty of heat units and frequent rainfall events, this was after a somewhat concerning start to June with a lack of warmth and sunshine.
Voting: Good - 14 Bad - 2
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Thu Jul 03, 2025
Hourly Wind Speed Climo
03 Jul 2025 05:30 AM
The featured chart presents a simple hourly wind speed climatology for Ames by month. The summer months of July and August generally have the slowest wind speeds with April and March having the strongest. Near surface wind speeds are driven by horizontal pressure gradients, which are the weakest during the aforementioned months. The chart also nicely shows the diurnal cycle with solar heating of the ground and then the air causing the lower atmosphere to vertically mix, which transports momentum aloft to the surface.
Voting: Good - 14 Bad - 0
Tags: wind
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03 Jul 2025 05:30 AM
The featured chart presents a simple hourly wind speed climatology for Ames by month. The summer months of July and August generally have the slowest wind speeds with April and March having the strongest. Near surface wind speeds are driven by horizontal pressure gradients, which are the weakest during the aforementioned months. The chart also nicely shows the diurnal cycle with solar heating of the ground and then the air causing the lower atmosphere to vertically mix, which transports momentum aloft to the surface.
Voting: Good - 14 Bad - 0
Tags: wind
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Mon Jul 07, 2025
3 PM July Temps
07 Jul 2025 05:30 AM
After a very hot Friday, abundant storms on Saturday and a northerly breeze on Sunday helped to knock down the temperatures a bit. The featured chart looks at yearly average 3 PM temperatures during July for Des Moines. A simple period of average is shown along with a linear trend line fit. The early value for 2025 comes in below average by a few degrees and matches the recent trend of not much variance from average. The forecast for this week has afternoon highs in the low to mid 80s, so certainly about average for the second week of July!
Voting: Good - 10 Bad - 0
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07 Jul 2025 05:30 AM
After a very hot Friday, abundant storms on Saturday and a northerly breeze on Sunday helped to knock down the temperatures a bit. The featured chart looks at yearly average 3 PM temperatures during July for Des Moines. A simple period of average is shown along with a linear trend line fit. The early value for 2025 comes in below average by a few degrees and matches the recent trend of not much variance from average. The forecast for this week has afternoon highs in the low to mid 80s, so certainly about average for the second week of July!
Voting: Good - 10 Bad - 0
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Tue Jul 08, 2025
IEM One App
08 Jul 2025 05:30 AM
The featured screenshot is from the IEM One App showing the combination of NWS NEXRAD Mosaic, NWS Alerts, and three webcams all valid around 8 PM Monday evening. This app was recently added to the website as hopefully a helpful means to quickly navigate IEM's massive archives of all three products. This app also has a number of other bells and whistles to it for you to explore and provide feedback on.
Voting: Good - 14 Bad - 1
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08 Jul 2025 05:30 AM
The featured screenshot is from the IEM One App showing the combination of NWS NEXRAD Mosaic, NWS Alerts, and three webcams all valid around 8 PM Monday evening. This app was recently added to the website as hopefully a helpful means to quickly navigate IEM's massive archives of all three products. This app also has a number of other bells and whistles to it for you to explore and provide feedback on.
Voting: Good - 14 Bad - 1
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Wed Jul 09, 2025
Comprehensive Climate Index
09 Jul 2025 05:30 AM
The Comprehensive Climate Index (CCI) is a weather variable composite index that combines air temperature, wind speed, relative humidity, and solar radiation. The CCI is typically presented as either a no-shade or shade option, which attempts to better account for the cooling effect of having shade available, which is something unaccounted for by more traditional indices like heat index. The featured map presents a grid calculation based on NOAA HRRR model data valid 3 PM Tuesday. The index is typically shown within the ranges found in the legend. So a number of locations yesterday were shown in the severe category for CCI. Look for more IEM tooling to come to show various CCI statistics and climatologies.
Voting: Good - 13 Bad - 2
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09 Jul 2025 05:30 AM
The Comprehensive Climate Index (CCI) is a weather variable composite index that combines air temperature, wind speed, relative humidity, and solar radiation. The CCI is typically presented as either a no-shade or shade option, which attempts to better account for the cooling effect of having shade available, which is something unaccounted for by more traditional indices like heat index. The featured map presents a grid calculation based on NOAA HRRR model data valid 3 PM Tuesday. The index is typically shown within the ranges found in the legend. So a number of locations yesterday were shown in the severe category for CCI. Look for more IEM tooling to come to show various CCI statistics and climatologies.
Voting: Good - 13 Bad - 2
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Thu Jul 10, 2025
Upcoming Five Days
10 Jul 2025 05:30 AM
The featured map presents Weather Prediction Center Quantitative Precipitation Forecast (QPF) between last night and Monday evening. A significant rainfall event is forecast with a large portion of this precipitation falling on Friday. Sadly, threats of Flash Flooding are certainly on everyone's mind with the recent and tragic Flash Flooding in Texas. This forecast paints the highest totals over west central Iowa with isolated amounts exceeding 3.5 inches. Of course, it is difficult to pinpoint where exactly such high amounts of rain will fall, but weather pattern recognition and an atmosphere loaded with water vapor will support such totals somewhere in Iowa.
Voting: Good - 23 Bad - 0
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10 Jul 2025 05:30 AM
The featured map presents Weather Prediction Center Quantitative Precipitation Forecast (QPF) between last night and Monday evening. A significant rainfall event is forecast with a large portion of this precipitation falling on Friday. Sadly, threats of Flash Flooding are certainly on everyone's mind with the recent and tragic Flash Flooding in Texas. This forecast paints the highest totals over west central Iowa with isolated amounts exceeding 3.5 inches. Of course, it is difficult to pinpoint where exactly such high amounts of rain will fall, but weather pattern recognition and an atmosphere loaded with water vapor will support such totals somewhere in Iowa.
Voting: Good - 23 Bad - 0
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Fri Jul 11, 2025
1993 July Benchmark
11 Jul 2025 05:30 AM
The heavy rainfall events continue to stack up this July as a persistent muggy air mass and passing disturbances fire complexes of storms about each day. The featured chart presents the monthly precipitation total records for Ames. The largest total shown is just over 16 inches during the epic July of 1993. So far, the total for Ames is nowhere near that total, but the daily accumulation for July 1993 didn't get started in earnest until a 4.65 inch event on the 9th.
Voting: Good - 18 Bad - 0
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11 Jul 2025 05:30 AM
The heavy rainfall events continue to stack up this July as a persistent muggy air mass and passing disturbances fire complexes of storms about each day. The featured chart presents the monthly precipitation total records for Ames. The largest total shown is just over 16 inches during the epic July of 1993. So far, the total for Ames is nowhere near that total, but the daily accumulation for July 1993 didn't get started in earnest until a 4.65 inch event on the 9th.
Voting: Good - 18 Bad - 0
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Mon Jul 14, 2025
Warning Proportions
14 Jul 2025 05:30 AM
The past few weeks have been very active over Iowa and beyond with severe weather and flooding rains prompting the NWS to issue numerous warnings over the state. The featured chart looks into the normalized frequency of Tornado, Severe Thunderstorm, and Flash Flood warnings by week of the year. The top panel presents data for the five weather forecast offices (WFO)s covering Iowa and the bottom panel is nationwide. There's a number of nice annual signals that appear within the two plots. Since we are normalizing between these three warning types, drawing individual inferences needs some consideration. Generally, the plot shows the effect of vertical wind shear and storm motion speed. Tornado warnings have the lowest relative frequency during July and August as the aforementioned vertical wind shear is the weakest and wind/hail severe storms are most common. The cold season months having the highest relative tornado warning frequency is interesting as shear increases and larger scale storm systems become more common. One note of caveat for Iowa during the winter months is that warning counts are much smaller, so the data is more noisy.
Voting: Good - 12 Bad - 0
Tags: ffw tor svr
14 Jul 2025 05:30 AM
The past few weeks have been very active over Iowa and beyond with severe weather and flooding rains prompting the NWS to issue numerous warnings over the state. The featured chart looks into the normalized frequency of Tornado, Severe Thunderstorm, and Flash Flood warnings by week of the year. The top panel presents data for the five weather forecast offices (WFO)s covering Iowa and the bottom panel is nationwide. There's a number of nice annual signals that appear within the two plots. Since we are normalizing between these three warning types, drawing individual inferences needs some consideration. Generally, the plot shows the effect of vertical wind shear and storm motion speed. Tornado warnings have the lowest relative frequency during July and August as the aforementioned vertical wind shear is the weakest and wind/hail severe storms are most common. The cold season months having the highest relative tornado warning frequency is interesting as shear increases and larger scale storm systems become more common. One note of caveat for Iowa during the winter months is that warning counts are much smaller, so the data is more noisy.
Voting: Good - 12 Bad - 0
Tags: ffw tor svr
Tue Jul 15, 2025
Corn Silking Progress
15 Jul 2025 05:30 AM
USDA NASS published their weekly crop progress update yesterday and today's featured chart checks in on their estimated corn silking progress for Iowa. The weekly progress data is plotted each year with white "X"s denoting when each year's 36% value occurred, which is the present 2025 estimate as of Sunday. The right hand plot presents a yearly trend line of this 36% value. The tasseling/silking stage of corn development is very important as excessive heat and/or moisture stress is shown to be detrimental to yield potential. Recent weather and the near term forecast continue to look bullish in this regard with limited overnight warm temperatures and continued chances of rain.
Voting: Good - 10 Bad - 0
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15 Jul 2025 05:30 AM
USDA NASS published their weekly crop progress update yesterday and today's featured chart checks in on their estimated corn silking progress for Iowa. The weekly progress data is plotted each year with white "X"s denoting when each year's 36% value occurred, which is the present 2025 estimate as of Sunday. The right hand plot presents a yearly trend line of this 36% value. The tasseling/silking stage of corn development is very important as excessive heat and/or moisture stress is shown to be detrimental to yield potential. Recent weather and the near term forecast continue to look bullish in this regard with limited overnight warm temperatures and continued chances of rain.
Voting: Good - 10 Bad - 0
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Wed Jul 16, 2025
YTD Flash Flood Warnings
16 Jul 2025 05:30 AM
NWS issued Flash Flood Warnings have certainly been in the headlines recently with the tragic flash flooding events in Texas, New Mexico, and other places. The featured chart presents an unofficial IEM accounting of the number of Flash Flood Warnings issued by NWS offices for the approximate year to date period. The 2025 total exceeds any previous year over the modern era. Of course, there are caveats as data quality decreases prior to the mid 1990s and there have been some warning methodology changes over the years, but still this year's total is certainly exceptional compared with recent years. The IEM autoplot that generated this image can also summarize for just warnings for Iowa and that total is only 30 for this year, which trails a number of previous years. Unfortunately, there will be chances for such warnings over the coming days as active weather returns.
Voting: Good - 9 Bad - 0
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16 Jul 2025 05:30 AM
NWS issued Flash Flood Warnings have certainly been in the headlines recently with the tragic flash flooding events in Texas, New Mexico, and other places. The featured chart presents an unofficial IEM accounting of the number of Flash Flood Warnings issued by NWS offices for the approximate year to date period. The 2025 total exceeds any previous year over the modern era. Of course, there are caveats as data quality decreases prior to the mid 1990s and there have been some warning methodology changes over the years, but still this year's total is certainly exceptional compared with recent years. The IEM autoplot that generated this image can also summarize for just warnings for Iowa and that total is only 30 for this year, which trails a number of previous years. Unfortunately, there will be chances for such warnings over the coming days as active weather returns.
Voting: Good - 9 Bad - 0
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Thu Jul 17, 2025
Mid-July Highs below 75
17 Jul 2025 05:30 AM
Forecast high temperatures for this fine Thursday are expected to struggle in the lower 70s for most of the state. So it is a good time to check in on how frequently this occurs. The featured map uses long term climate sites in the state and plots the percentage of years that have at least one day between 10 and 20 July with a high temperature below 75°F. Most of these stations have a period of record lasting at least 70 years. The map shows an intuitive north to south pattern with higher frequencies found over the north. An overall average is about 25%, so about once every four years this situation happens at least once for the year over this specific period of days.
Voting: Good - 8 Bad - 1
Tags: jul
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17 Jul 2025 05:30 AM
Forecast high temperatures for this fine Thursday are expected to struggle in the lower 70s for most of the state. So it is a good time to check in on how frequently this occurs. The featured map uses long term climate sites in the state and plots the percentage of years that have at least one day between 10 and 20 July with a high temperature below 75°F. Most of these stations have a period of record lasting at least 70 years. The map shows an intuitive north to south pattern with higher frequencies found over the north. An overall average is about 25%, so about once every four years this situation happens at least once for the year over this specific period of days.
Voting: Good - 8 Bad - 1
Tags: jul
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Fri Jul 18, 2025
Cool July Afternoon
18 Jul 2025 05:30 AM
On average, mid July is the warmest time of the year. But it is certainly not always the case and Thursday's high temperatures were quite pleasant with low to mid 70s over Iowa. The featured map presents an analysis of fifteen minute interval NOAA RTMA temperature analyses to produce a maximum value during Thursday afternoon. The coolest values found are near Dubuque around 70°F and higher values a number of places elsewhere only in the upper 70s. Among the airport weather stations, Dubuque was the coolest as well with a high of just 69°F. Enjoy this weather while it lasts as full blown summer heat returns next week!
Voting: Good - 16 Bad - 0
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18 Jul 2025 05:30 AM
On average, mid July is the warmest time of the year. But it is certainly not always the case and Thursday's high temperatures were quite pleasant with low to mid 70s over Iowa. The featured map presents an analysis of fifteen minute interval NOAA RTMA temperature analyses to produce a maximum value during Thursday afternoon. The coolest values found are near Dubuque around 70°F and higher values a number of places elsewhere only in the upper 70s. Among the airport weather stations, Dubuque was the coolest as well with a high of just 69°F. Enjoy this weather while it lasts as full blown summer heat returns next week!
Voting: Good - 16 Bad - 0
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