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.
Mon Apr 01, 2024
Eight Straight Months
01 Apr 2024 05:30 AM
The first three months of 2024 are in the books and March was yet another month with an above average temperature. The featured chart presents IEM estimated monthly Iowa areal averaged temperature along with the Nino 3.4 index. The recent El Nino is likely explaining much of our recent warmth as March will be the eighth straight month above average for Iowa. The present near term and monthly outlook for April looks to continue the above average temperature trend for this month as well.
Voting: Good - 9 Bad - 0
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01 Apr 2024 05:30 AM
The first three months of 2024 are in the books and March was yet another month with an above average temperature. The featured chart presents IEM estimated monthly Iowa areal averaged temperature along with the Nino 3.4 index. The recent El Nino is likely explaining much of our recent warmth as March will be the eighth straight month above average for Iowa. The present near term and monthly outlook for April looks to continue the above average temperature trend for this month as well.
Voting: Good - 9 Bad - 0
Generate This Chart on Website
Tue Apr 02, 2024
Just -10°F for Decorah
02 Apr 2024 05:30 AM
Our most recently finished winter season was a mild one for Iowa. One way to measure how mild it was is to plot the accumulated season to date minimum temperature. Today's featured chart does just that for Decorah (far NE Iowa). The blue line represents the 2023-2024 value with the other areas and lines showing the climatology and climatological range. The value this year of -10°F comes just outside the 97.5th percentile on record. This value came with the brief, but intense cold during the middle of January. For those of you that don't wish to think of winter any more, the good news is that the cold season minimum temperature has never happened during the month of April in Iowa.
Voting: Good - 10 Bad - 0
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02 Apr 2024 05:30 AM
Our most recently finished winter season was a mild one for Iowa. One way to measure how mild it was is to plot the accumulated season to date minimum temperature. Today's featured chart does just that for Decorah (far NE Iowa). The blue line represents the 2023-2024 value with the other areas and lines showing the climatology and climatological range. The value this year of -10°F comes just outside the 97.5th percentile on record. This value came with the brief, but intense cold during the middle of January. For those of you that don't wish to think of winter any more, the good news is that the cold season minimum temperature has never happened during the month of April in Iowa.
Voting: Good - 10 Bad - 0
Generate This Chart on Website
Wed Apr 03, 2024
'23-'24 Winter Storm #16
03 Apr 2024 08:23 AM
As with other recent winter storms, we've got another difficult to measure snow producing storm impacting Iowa this Wednesday morning. The featured map attempts to analyze available NWS and CoCoRaHS reports and finds the highest totals confined to far eastern Iowa. Some of this snow fell yesterday afternoon and quickly melted. Additional snow is falling at the time of posting this featured map, so the analysis will likely be updated tomorrow when more NWS COOP reports are received. Early April snowfalls are certainly nothing out of the ordinary for Iowa and any bit of sunshine will make quick work of melting it away.
Voting: Good - 8 Bad - 0
Tags: winter2324
03 Apr 2024 08:23 AM
As with other recent winter storms, we've got another difficult to measure snow producing storm impacting Iowa this Wednesday morning. The featured map attempts to analyze available NWS and CoCoRaHS reports and finds the highest totals confined to far eastern Iowa. Some of this snow fell yesterday afternoon and quickly melted. Additional snow is falling at the time of posting this featured map, so the analysis will likely be updated tomorrow when more NWS COOP reports are received. Early April snowfalls are certainly nothing out of the ordinary for Iowa and any bit of sunshine will make quick work of melting it away.
Voting: Good - 8 Bad - 0
Tags: winter2324
Thu Apr 04, 2024
Short vs Long Term Drought
04 Apr 2024 05:30 AM
Parts of eastern Iowa have received quite a bit of precipitation over the past seven days. The drought situation is certainly being helped out in this area, but not all sites have seen enough precipitation to put a significant dent into long term deficits. Case in point is Cedar Rapids, with just about an inch over the past nine days not registering much of a change in the longer term departure. The chart shows trailing 31, 91, and 365 day departures along with the weekly US Drought Monitor classification underlain. So while the short term departures are both slightly above average, the 365 day departure remains at significant levels below average.
Voting: Good - 13 Bad - 0
Generate This Chart on Website
04 Apr 2024 05:30 AM
Parts of eastern Iowa have received quite a bit of precipitation over the past seven days. The drought situation is certainly being helped out in this area, but not all sites have seen enough precipitation to put a significant dent into long term deficits. Case in point is Cedar Rapids, with just about an inch over the past nine days not registering much of a change in the longer term departure. The chart shows trailing 31, 91, and 365 day departures along with the weekly US Drought Monitor classification underlain. So while the short term departures are both slightly above average, the 365 day departure remains at significant levels below average.
Voting: Good - 13 Bad - 0
Generate This Chart on Website
Fri Apr 05, 2024
La Crosse Snowfall
05 Apr 2024 05:30 AM
The featured infographic is courtesy of NWS La Crosse, WI. We, who live in the Midwest, generally do not think much about elevation effects when it comes to winter precipitation as "flat as a pancake" accurately describes our topography. Those is more mountainous terrain certainly understand that elevation makes a big difference with precipitation type and even the weather. For those of you unaware, temperatures generally decrease with increasing elevation so precipitation that falls as rain at lower elevations will fall as snow as you go up the mountain and temperatures cool below freezing. Hence why you can get big snow storms at the top of the mountains in Hawaii. Anyway, so it is interesting to see an elevation effect show up just to our north and east in La Crosse, Wisconsin. The most recent snow storm produced a remarkable difference in snow totals between the airport (1.1") located along the Mississippi River and the NWS forecast office (16.6") located at the top of a nearby bluff just five miles away, but 600 some feet higher up. While the elevation difference did play a role in this event, there was also a persistent band of snow that impacted the forecast office location and the airport is helped by warmth from the nearby river. The top right panel shows that the forecast office gets more snow, on average, than the airport.
Voting: Good - 16 Bad - 0
Tags: elevation
05 Apr 2024 05:30 AM
The featured infographic is courtesy of NWS La Crosse, WI. We, who live in the Midwest, generally do not think much about elevation effects when it comes to winter precipitation as "flat as a pancake" accurately describes our topography. Those is more mountainous terrain certainly understand that elevation makes a big difference with precipitation type and even the weather. For those of you unaware, temperatures generally decrease with increasing elevation so precipitation that falls as rain at lower elevations will fall as snow as you go up the mountain and temperatures cool below freezing. Hence why you can get big snow storms at the top of the mountains in Hawaii. Anyway, so it is interesting to see an elevation effect show up just to our north and east in La Crosse, Wisconsin. The most recent snow storm produced a remarkable difference in snow totals between the airport (1.1") located along the Mississippi River and the NWS forecast office (16.6") located at the top of a nearby bluff just five miles away, but 600 some feet higher up. While the elevation difference did play a role in this event, there was also a persistent band of snow that impacted the forecast office location and the airport is helped by warmth from the nearby river. The top right panel shows that the forecast office gets more snow, on average, than the airport.
Voting: Good - 16 Bad - 0
Tags: elevation
Sun Apr 07, 2024
Eclipse Cloud Cover Forecast
07 Apr 2024 08:09 AM
The featured map is courtesy of an excellent website by Tomer Burg. The map shows a cloud cover forecast for Monday afternoon from the NWS National Blend of Models. Blue colors indicate less clouds and gray indicate more. There is still plenty of time for this forecast to change, but southern Illinois (and then adjusting on Monday as traffic allows) continues to look like the safest bet for any Iowans that are still wondering where the go. Given the consistent and poor forecast in Texas, the traffic situation seems problematic for areas to the north and east as some of those folks attempt to move in that direction. If you don't wish to leave Iowa, the far southeastern tip continues to look optimistic for being able to see a near full eclipse (~90% coverage) from that location!
Voting: Good - 6 Bad - 0
Tags: eclipse
07 Apr 2024 08:09 AM
The featured map is courtesy of an excellent website by Tomer Burg. The map shows a cloud cover forecast for Monday afternoon from the NWS National Blend of Models. Blue colors indicate less clouds and gray indicate more. There is still plenty of time for this forecast to change, but southern Illinois (and then adjusting on Monday as traffic allows) continues to look like the safest bet for any Iowans that are still wondering where the go. Given the consistent and poor forecast in Texas, the traffic situation seems problematic for areas to the north and east as some of those folks attempt to move in that direction. If you don't wish to leave Iowa, the far southeastern tip continues to look optimistic for being able to see a near full eclipse (~90% coverage) from that location!
Voting: Good - 6 Bad - 0
Tags: eclipse
Mon Apr 08, 2024
Eclipse in weather models
08 Apr 2024 06:17 AM
The eclipse is finally at hand and hopefully you are able to see it wherever you may or may not have traveled to. While the eclipse at totality only lasts a few minutes, the shadow effects while the moon is partially blocking the sun lasts for an hour or two. The HRRR model includes special code to account for the change in received solar radiation during the eclipse. With instantaneous solar radiation output from the model at 15 minute resolution, the featured lapse nicely shows the impact of the eclipse. You may be wondering about the darkened areas already on the map. That is the effect of clouds reducing the solar radiation received at earth's surface.
Voting: Good - 10 Bad - 0
Tags: eclipse hrrr
08 Apr 2024 06:17 AM
The eclipse is finally at hand and hopefully you are able to see it wherever you may or may not have traveled to. While the eclipse at totality only lasts a few minutes, the shadow effects while the moon is partially blocking the sun lasts for an hour or two. The HRRR model includes special code to account for the change in received solar radiation during the eclipse. With instantaneous solar radiation output from the model at 15 minute resolution, the featured lapse nicely shows the impact of the eclipse. You may be wondering about the darkened areas already on the map. That is the effect of clouds reducing the solar radiation received at earth's surface.
Voting: Good - 10 Bad - 0
Tags: eclipse hrrr
Tue Apr 09, 2024
Inversion Data During Eclipse
09 Apr 2024 05:41 AM
The featured chart is from the inversion station near Crawfordsville on the ISU Southeast Farm. The plot focuses in on the period around the eclipse yesterday afternoon. The top panel traces air temperature at 1.5, 5, and 10 feet above the ground surface. The second panel differences the 10 and 1.5 foot values. The bottom panel plots wind speed and gusts at 10 foot. This beautiful plot shows what happens when the eclipse starts rapidly decreasing solar energy as the near surface temperature cools more quickly than levels further away. A temperature inversion then sets up with the 10 foot value warmer than 1.5. This period also features a decrease in wind speed as vertical mixing decreases. Once the eclipse period ends, the various data traces return to about how they were prior to the eclipse.
Voting: Good - 15 Bad - 0
Tags: eclipse
Generate This Chart on Website
09 Apr 2024 05:41 AM
The featured chart is from the inversion station near Crawfordsville on the ISU Southeast Farm. The plot focuses in on the period around the eclipse yesterday afternoon. The top panel traces air temperature at 1.5, 5, and 10 feet above the ground surface. The second panel differences the 10 and 1.5 foot values. The bottom panel plots wind speed and gusts at 10 foot. This beautiful plot shows what happens when the eclipse starts rapidly decreasing solar energy as the near surface temperature cools more quickly than levels further away. A temperature inversion then sets up with the 10 foot value warmer than 1.5. This period also features a decrease in wind speed as vertical mixing decreases. Once the eclipse period ends, the various data traces return to about how they were prior to the eclipse.
Voting: Good - 15 Bad - 0
Tags: eclipse
Generate This Chart on Website
Wed Apr 10, 2024
Frequency of below 20
10 Apr 2024 05:30 AM
The featured map is from a recently added "autoplot" that allows plotting the percentage of years over a given period of days that had at least one day below or above some threshold. In this case, the map shows the frequency of having at least one daily low temperature below 20°F between 10 April an 31 May. There is certainly a north to south gradient to be found with some locations near one third and others in far southeastern Iowa closer to zero. The near term forecast has plenty of warm weather and little in the way of cold temperatures, but there is still plenty of time yet for sub freezing temperatures. In fact, you can follow the generate this chart link and re-generate this chart but for a threshold of 32°F and find out!
Voting: Good - 11 Bad - 0
Generate This Chart on Website
10 Apr 2024 05:30 AM
The featured map is from a recently added "autoplot" that allows plotting the percentage of years over a given period of days that had at least one day below or above some threshold. In this case, the map shows the frequency of having at least one daily low temperature below 20°F between 10 April an 31 May. There is certainly a north to south gradient to be found with some locations near one third and others in far southeastern Iowa closer to zero. The near term forecast has plenty of warm weather and little in the way of cold temperatures, but there is still plenty of time yet for sub freezing temperatures. In fact, you can follow the generate this chart link and re-generate this chart but for a threshold of 32°F and find out!
Voting: Good - 11 Bad - 0
Generate This Chart on Website
Thu Apr 11, 2024
101 Days In
11 Apr 2024 05:30 AM
Yesterday was the 101st day of the year and yet another day this year without significant cold temperatures. The featured chart presents hourly air temperature observations from the Ames airport with the blue shaded region representing the range between the daily high and low climatology. The one cold stretch during the middle of January is about all there is for significant cold this year. It is also interesting that our warmest temperature so far this April has yet to top the warmest temperature of both February and March! This may change later in the week and into the weekend with warmer temperatures forecast and even elevated humidity levels.
Voting: Good - 12 Bad - 0
Generate This Chart on Website
11 Apr 2024 05:30 AM
Yesterday was the 101st day of the year and yet another day this year without significant cold temperatures. The featured chart presents hourly air temperature observations from the Ames airport with the blue shaded region representing the range between the daily high and low climatology. The one cold stretch during the middle of January is about all there is for significant cold this year. It is also interesting that our warmest temperature so far this April has yet to top the warmest temperature of both February and March! This may change later in the week and into the weekend with warmer temperatures forecast and even elevated humidity levels.
Voting: Good - 12 Bad - 0
Generate This Chart on Website
Fri Apr 12, 2024
Calendar of SPS Counts
12 Apr 2024 05:30 AM
The Special Weather Statement (abbreviated SPS for complex reasons) is one of the product tools available to NWS forecast offices to alert the public to immediate weather events. It can be used to alert the public to just below severe criterion storms. In fact, the SPS has been updated over the years to carry many of the same tags that are included in Severe Thunderstorm Warnings, such as max hail size and wind gusts. They also can be issued for a specific geographic area within an included polygon. NWS Quad Cities issued three such SPSs yesterday (1, 2, and 3). The featured chart presents the number of such SPS products that included polygons by day of the year for the office. The IEM attempts to curate an archive of these SPS products, which includes a download portal and an archive search by point.
Voting: Good - 14 Bad - 1
Tags: sps
Generate This Chart on Website
12 Apr 2024 05:30 AM
The Special Weather Statement (abbreviated SPS for complex reasons) is one of the product tools available to NWS forecast offices to alert the public to immediate weather events. It can be used to alert the public to just below severe criterion storms. In fact, the SPS has been updated over the years to carry many of the same tags that are included in Severe Thunderstorm Warnings, such as max hail size and wind gusts. They also can be issued for a specific geographic area within an included polygon. NWS Quad Cities issued three such SPSs yesterday (1, 2, and 3). The featured chart presents the number of such SPS products that included polygons by day of the year for the office. The IEM attempts to curate an archive of these SPS products, which includes a download portal and an archive search by point.
Voting: Good - 14 Bad - 1
Tags: sps
Generate This Chart on Website
Mon Apr 15, 2024
First 88
15 Apr 2024 05:30 AM
For mid April, this past weekend was quite warm. Temperatures soared into the 80s on Sunday with Des Moines setting a record high of 88. The featured chart presents the first date each calendar year with a high temperature of at least 88 degrees for Des Moines. The right hand side lists the top 10 earliest and latest dates. Sunday comes in 9th earliest on this listing. The average first date is not until 21 May. We'll take another run at 80 degrees on Monday before thunderstorms move in and slightly cooler temperatures.
Voting: Good - 10 Bad - 0
Generate This Chart on Website
15 Apr 2024 05:30 AM
For mid April, this past weekend was quite warm. Temperatures soared into the 80s on Sunday with Des Moines setting a record high of 88. The featured chart presents the first date each calendar year with a high temperature of at least 88 degrees for Des Moines. The right hand side lists the top 10 earliest and latest dates. Sunday comes in 9th earliest on this listing. The average first date is not until 21 May. We'll take another run at 80 degrees on Monday before thunderstorms move in and slightly cooler temperatures.
Voting: Good - 10 Bad - 0
Generate This Chart on Website
Tue Apr 16, 2024
Hatched Tornado Risk
16 Apr 2024 05:37 AM
The Storm Prediction Center issues a number of products including a convective outlook, which provides a spatial analysis of severe weather risk. For the "Day 1" product, individual threat risks are forecast for tornadoes, damaging wind gusts, and hail. On the SPC website, one of the risk categories is colloquially known as the "hatched" risk as it is visually presented as a hatched area on the map, when forecast. This area represents the possibility of significant tornado, wind, or hail risks. For Iowa today, the present Day 1 outlook has much of Iowa within such a hatched risk for tornadoes, meaning a likelihood of EF2 and stronger tornadoes. The featured chart looks at the frequency and yearly period of such a risk threshold for Iowa. The right hand side denotes the first and last date each year along with the number of dates with such a risk threshold present. For Iowa, these events are thankfully only about a handful of times per year. The year 2021 is certainly an outlier with the only event being associated with the serial derecho on 15 December.
Voting: Good - 12 Bad - 0
Tags: spc
Generate This Chart on Website
16 Apr 2024 05:37 AM
The Storm Prediction Center issues a number of products including a convective outlook, which provides a spatial analysis of severe weather risk. For the "Day 1" product, individual threat risks are forecast for tornadoes, damaging wind gusts, and hail. On the SPC website, one of the risk categories is colloquially known as the "hatched" risk as it is visually presented as a hatched area on the map, when forecast. This area represents the possibility of significant tornado, wind, or hail risks. For Iowa today, the present Day 1 outlook has much of Iowa within such a hatched risk for tornadoes, meaning a likelihood of EF2 and stronger tornadoes. The featured chart looks at the frequency and yearly period of such a risk threshold for Iowa. The right hand side denotes the first and last date each year along with the number of dates with such a risk threshold present. For Iowa, these events are thankfully only about a handful of times per year. The year 2021 is certainly an outlier with the only event being associated with the serial derecho on 15 December.
Voting: Good - 12 Bad - 0
Tags: spc
Generate This Chart on Website