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.
Wed Jan 01, 2025
'24-'25 Winter Storm #5
01 Jan 2025 12:54 PM
While most of the precipitation from the storm impacting the state Monday into Tuesday fell as rain, a few locations picked up measurable snowfall with an isolated area west of Des Moines picking up over two inches. The featured map presents available NWS COOP, Local Storm Reports, and CoCoRaHS reports over the past two days. Some of the snow did quickly melt with the change over to rain, so totals were difficult to measure and report. Our weather pattern looks to remain active to start off 2025 with the next accumulating snow storm arriving Thursday and a likely bigger storm to end the upcoming weekend.
Voting: Good - 13 Bad - 0
Tags: winter2425
01 Jan 2025 12:54 PM
While most of the precipitation from the storm impacting the state Monday into Tuesday fell as rain, a few locations picked up measurable snowfall with an isolated area west of Des Moines picking up over two inches. The featured map presents available NWS COOP, Local Storm Reports, and CoCoRaHS reports over the past two days. Some of the snow did quickly melt with the change over to rain, so totals were difficult to measure and report. Our weather pattern looks to remain active to start off 2025 with the next accumulating snow storm arriving Thursday and a likely bigger storm to end the upcoming weekend.
Voting: Good - 13 Bad - 0
Tags: winter2425
Thu Jan 02, 2025
'24-'25 Winter Storm #6
02 Jan 2025 10:28 PM
A compact and quick moving winter storm dumped a stripe of two to four inches on Thursday between roughly Sioux City to Davenport. The featured map presents an analysis of mostly NWS Local Storm Reports as much of the once-daily COOP data will be arriving Friday morning. So the map will be updated once those additional reports arrive along with any CoCoRaHS reports. The map also plots the three Snow Squall Warnings polygons issued by NWS Des Moines as intense snowfall rates impacted the morning work commute. Attention is quickly turning to a much larger storm complex forecast to arrive late this weekend, with the largest snowfall totals forecast to clip southern Iowa along with a sharp gradient in totals to the north.
Voting: Good - 19 Bad - 5
Tags: winter2425
02 Jan 2025 10:28 PM
A compact and quick moving winter storm dumped a stripe of two to four inches on Thursday between roughly Sioux City to Davenport. The featured map presents an analysis of mostly NWS Local Storm Reports as much of the once-daily COOP data will be arriving Friday morning. So the map will be updated once those additional reports arrive along with any CoCoRaHS reports. The map also plots the three Snow Squall Warnings polygons issued by NWS Des Moines as intense snowfall rates impacted the morning work commute. Attention is quickly turning to a much larger storm complex forecast to arrive late this weekend, with the largest snowfall totals forecast to clip southern Iowa along with a sharp gradient in totals to the north.
Voting: Good - 19 Bad - 5
Tags: winter2425
Mon Jan 06, 2025
'24-'25 Winter Storm #7
06 Jan 2025 08:01 AM
A major winter storm brought freezing rain and heavy snow from Kansas to now D.C. Iowa barely got clipped by the event with a sharp northern side gradient to the heaviest snowfall totals as dry air over Iowa fought off the snow. The featured analysis is struggling to show the tight gradient that exists over the southern tier of Iowa counties with a limited number of reports in the area. Our recently active weather pattern looks to settle down a bit this week with seasonal cold air in place and not much in the way of precipitation chances.
Voting: Good - 13 Bad - 0
Tags: winter2425
06 Jan 2025 08:01 AM
A major winter storm brought freezing rain and heavy snow from Kansas to now D.C. Iowa barely got clipped by the event with a sharp northern side gradient to the heaviest snowfall totals as dry air over Iowa fought off the snow. The featured analysis is struggling to show the tight gradient that exists over the southern tier of Iowa counties with a limited number of reports in the area. Our recently active weather pattern looks to settle down a bit this week with seasonal cold air in place and not much in the way of precipitation chances.
Voting: Good - 13 Bad - 0
Tags: winter2425
Tue Jan 07, 2025
January Brisk Winds By Temp
07 Jan 2025 05:30 AM
Cold temperatures and a brisk wind created for sub zero wind chill temperatures Monday morning across most of Iowa. The featured chart looks into the frequency of having a wind speed of at least 10 knot (~12 MPH) for a given air temperature during January for Ames. The signal shown nicely illustrates the relationship between the two with the most interesting things happening at the temperature extremes. For the warmest temperatures, the frequency increases as the typical weather pattern needed to support such elevated temperatures involves the transport of warmer air masses from the south and mixing down of warmer air aloft. For the coldest temperatures, the micro-climate of the station favors "cold air drainage" situations, which usually need reduced wind speeds. There are also situations when transport of arctic air is involved, so frequencies do not necessarily go to zero at the coldest of temperatures.
Voting: Good - 7 Bad - 0
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07 Jan 2025 05:30 AM
Cold temperatures and a brisk wind created for sub zero wind chill temperatures Monday morning across most of Iowa. The featured chart looks into the frequency of having a wind speed of at least 10 knot (~12 MPH) for a given air temperature during January for Ames. The signal shown nicely illustrates the relationship between the two with the most interesting things happening at the temperature extremes. For the warmest temperatures, the frequency increases as the typical weather pattern needed to support such elevated temperatures involves the transport of warmer air masses from the south and mixing down of warmer air aloft. For the coldest temperatures, the micro-climate of the station favors "cold air drainage" situations, which usually need reduced wind speeds. There are also situations when transport of arctic air is involved, so frequencies do not necessarily go to zero at the coldest of temperatures.
Voting: Good - 7 Bad - 0
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Wed Jan 08, 2025
Recent Inversion Timing
08 Jan 2025 05:30 AM
Iowa State University has three of its "Soil Moisture Network" stations outfitted with additional temperature and wind sensors to help diagnose near surface temperature inversions. The primary application of this data is for agricultural spraying operations, but for meteorologists, the data can be interesting to look at any time of the year. The featured plot presents the difference between the 10 foot and 1.5 foot above ground level air temperature for a site near Ames. Red shading indicates that the 10 foot temperature is warmer. The plot shows the minute by minute values since 1 December. Of interest are many of the recent days since the arrival of modest snow cover. The presence of snow is a game changer for the surface energy budget with the primary impact being the redirection of much of the sun's inbound energy back into the atmosphere instead of heating the ground and helping to warm near surface air temperatures.
Voting: Good - 10 Bad - 1
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08 Jan 2025 05:30 AM
Iowa State University has three of its "Soil Moisture Network" stations outfitted with additional temperature and wind sensors to help diagnose near surface temperature inversions. The primary application of this data is for agricultural spraying operations, but for meteorologists, the data can be interesting to look at any time of the year. The featured plot presents the difference between the 10 foot and 1.5 foot above ground level air temperature for a site near Ames. Red shading indicates that the 10 foot temperature is warmer. The plot shows the minute by minute values since 1 December. Of interest are many of the recent days since the arrival of modest snow cover. The presence of snow is a game changer for the surface energy budget with the primary impact being the redirection of much of the sun's inbound energy back into the atmosphere instead of heating the ground and helping to warm near surface air temperatures.
Voting: Good - 10 Bad - 1
Generate This Chart on Website
Thu Jan 09, 2025
Frozen start to 2025
09 Jan 2025 05:30 AM
For some parts of the state, the first eight days of 2025 have been below freezing. One such example is Mason City. The featured chart presents the number of days during the first eight days of each year that the high temperature was above 32°F. The zero for 2025 is the first since 2010, but roughly 1/4 of the years on record have had a similar start to this year. While this plot doesn't correlate these numbers with snow depth, a manual calculation shows that nearly all of those years with six to eight days had no snow cover and vice versa, most years with zero had snow cover.
Voting: Good - 10 Bad - 0
Generate This Chart on Website
09 Jan 2025 05:30 AM
For some parts of the state, the first eight days of 2025 have been below freezing. One such example is Mason City. The featured chart presents the number of days during the first eight days of each year that the high temperature was above 32°F. The zero for 2025 is the first since 2010, but roughly 1/4 of the years on record have had a similar start to this year. While this plot doesn't correlate these numbers with snow depth, a manual calculation shows that nearly all of those years with six to eight days had no snow cover and vice versa, most years with zero had snow cover.
Voting: Good - 10 Bad - 0
Generate This Chart on Website
Fri Jan 10, 2025
GeoTIFF Export
10 Jan 2025 05:30 AM
The IEM Autoplot tool has two general goals. The first is to generate visualizations of often complex datasets on-the-fly with considerable freedom given to the user to customize the presentation. The second is to give the user the option to download the raw data behind the visualization to allow for usage within their visualization or statistical software package of choice. To further support the extensibility goal, a number of autoplots that generate maps of grid based data are now able to export that data as a GeoTIFF. A GeoTIFF is a common and open GIS format for raster data. Note that the export is the raw data as a single band of floating point data values, not the visualization with color ramp and associated cartography. So today's featured plot is a mundane heatmap of NWS Severe Thunderstorm Warning polygons over Iowa for 2024. You can export the raster of event counts as a GeoTIFF and do further analysis to your heart's content. The option to generate these GeoTIFFs will be found as a button link below the generated maps within the autoplot tooling. As always, feedback on the autoplots and functionality is appreciated!
Voting: Good - 16 Bad - 41
Generate This Chart on Website
10 Jan 2025 05:30 AM
The IEM Autoplot tool has two general goals. The first is to generate visualizations of often complex datasets on-the-fly with considerable freedom given to the user to customize the presentation. The second is to give the user the option to download the raw data behind the visualization to allow for usage within their visualization or statistical software package of choice. To further support the extensibility goal, a number of autoplots that generate maps of grid based data are now able to export that data as a GeoTIFF. A GeoTIFF is a common and open GIS format for raster data. Note that the export is the raw data as a single band of floating point data values, not the visualization with color ramp and associated cartography. So today's featured plot is a mundane heatmap of NWS Severe Thunderstorm Warning polygons over Iowa for 2024. You can export the raster of event counts as a GeoTIFF and do further analysis to your heart's content. The option to generate these GeoTIFFs will be found as a button link below the generated maps within the autoplot tooling. As always, feedback on the autoplots and functionality is appreciated!
Voting: Good - 16 Bad - 41
Generate This Chart on Website
Mon Jan 13, 2025
January Daily Climo
13 Jan 2025 05:40 AM
The featured chart presents daily high, low, and average temperature climatologies for Ames during January. The lines represent the two most recent official climatologies from NCEI. These 30 year averages are updated once per decade. The bars presents the simple computed average based on period of record observations. The immediate difference between the two climatology datasets is explained by NCEI attempting to smooth out day to day variability due to individual weather events. Focusing on the NCEI lines, it is interesting to denote the subtle differences between the high and low temperature lines and how that impacts the overall average between the two. Our average high temperature is just starting to creep upwards, while our low temperature still has about a week to go before bottoming out. This difference is another example of thermal inertia as increasing solar inputs help to increase day time temperatures slightly, but more time is needed for the change to be felt with low temperatures.
Voting: Good - 10 Bad - 1
Generate This Chart on Website
13 Jan 2025 05:40 AM
The featured chart presents daily high, low, and average temperature climatologies for Ames during January. The lines represent the two most recent official climatologies from NCEI. These 30 year averages are updated once per decade. The bars presents the simple computed average based on period of record observations. The immediate difference between the two climatology datasets is explained by NCEI attempting to smooth out day to day variability due to individual weather events. Focusing on the NCEI lines, it is interesting to denote the subtle differences between the high and low temperature lines and how that impacts the overall average between the two. Our average high temperature is just starting to creep upwards, while our low temperature still has about a week to go before bottoming out. This difference is another example of thermal inertia as increasing solar inputs help to increase day time temperatures slightly, but more time is needed for the change to be felt with low temperatures.
Voting: Good - 10 Bad - 1
Generate This Chart on Website
Tue Jan 14, 2025
S California Fire Wx
14 Jan 2025 05:30 AM
In addition to convective outlooks, the Storm Prediction Center issues a fire weather outlook. The featured chart presents the daily maximum SPC fire weather outlook for the NWS Los Angeles forecast area since 2006. The chart shows the fire weather season mostly confined to the fall and early winter season, but events can happen about any time of year. The recent combination of down-slope wind and dry vegetation have materialized dangerous fire weather conditions. SPC has issued a couple of "Extreme" categorical outlook risks over the past week, which is something akin to the convective "High" risk that us Iowans have some experience with. Unfortunately, the fire weather risk looks to continue this week for the area with no precipitation forecast for the near term.
Voting: Good - 11 Bad - 0
Tags: fire
Generate This Chart on Website
14 Jan 2025 05:30 AM
In addition to convective outlooks, the Storm Prediction Center issues a fire weather outlook. The featured chart presents the daily maximum SPC fire weather outlook for the NWS Los Angeles forecast area since 2006. The chart shows the fire weather season mostly confined to the fall and early winter season, but events can happen about any time of year. The recent combination of down-slope wind and dry vegetation have materialized dangerous fire weather conditions. SPC has issued a couple of "Extreme" categorical outlook risks over the past week, which is something akin to the convective "High" risk that us Iowans have some experience with. Unfortunately, the fire weather risk looks to continue this week for the area with no precipitation forecast for the near term.
Voting: Good - 11 Bad - 0
Tags: fire
Generate This Chart on Website
Wed Jan 15, 2025
'24-'25 Winter Storm #8
15 Jan 2025 05:30 AM
While not much for a winter storm, an isolated area near Fort Dodge reported the IEM-analysis-map-arbitrary total of at least two inches of snow overnight into Tuesday morning. Totals an inch or less were common over the rest of the state. Other reports of an inch were found in a line from Fort Dodge to Davenport. The forecast continues to show warming temperatures for the rest of this week before a significant cold air outbreak arrives for early next week.
Voting: Good - 13 Bad - 2
Tags: winter2425
15 Jan 2025 05:30 AM
While not much for a winter storm, an isolated area near Fort Dodge reported the IEM-analysis-map-arbitrary total of at least two inches of snow overnight into Tuesday morning. Totals an inch or less were common over the rest of the state. Other reports of an inch were found in a line from Fort Dodge to Davenport. The forecast continues to show warming temperatures for the rest of this week before a significant cold air outbreak arrives for early next week.
Voting: Good - 13 Bad - 2
Tags: winter2425
Thu Jan 16, 2025
Snowfall Departure
16 Jan 2025 05:30 AM
The featured map presents season to date snowfall departures for NWS Daily CLImate reporting sites. An interactive map version of this data is available as well. The map shows the regional contrast in accumulated snow with above average values confined to the southern portion of the Midwest and a few spots that receive lake effect near the Great Lakes. With an upcoming and brief stretch of above freezing temperatures, a good chunk of what snow cover that exists over Iowa will melt. This will be followed by a period of deep freeze weather with highs struggling in the single digits. Such cold weather without any insulating snow cover can have impacts for frost depth penetration within the soil and over-wintering hardiness of some plants.
Voting: Good - 9 Bad - 1
Generate This Chart on Website
16 Jan 2025 05:30 AM
The featured map presents season to date snowfall departures for NWS Daily CLImate reporting sites. An interactive map version of this data is available as well. The map shows the regional contrast in accumulated snow with above average values confined to the southern portion of the Midwest and a few spots that receive lake effect near the Great Lakes. With an upcoming and brief stretch of above freezing temperatures, a good chunk of what snow cover that exists over Iowa will melt. This will be followed by a period of deep freeze weather with highs struggling in the single digits. Such cold weather without any insulating snow cover can have impacts for frost depth penetration within the soil and over-wintering hardiness of some plants.
Voting: Good - 9 Bad - 1
Generate This Chart on Website
Fri Jan 17, 2025
January Temperature Range
17 Jan 2025 05:30 AM
Temperatures warmed nicely on Thursday and with the slightly lengthening days, perhaps some of you were starting to dream of spring! Of course, we very much have a majority of the winter season yet to come and the near term forecast has the coldest air of the season arriving this very weekend. Today's featured chart checks in on the observed temperature range during January for Ames. The top panel shows the yearly maximum high temperature, middle panel presents the minimum low temperature, and finally the bottom panel shows the difference between the two (the range). Each dataset is fit with a simple average and a trailing 30 year average. Thanks to the lack of significant warmth and cold this year, the range is currently near the lowest of what has been observed on record. January is only half over, so there is plenty of time for each extreme to be exceeded and the range increased.
Voting: Good - 9 Bad - 18
Generate This Chart on Website
17 Jan 2025 05:30 AM
Temperatures warmed nicely on Thursday and with the slightly lengthening days, perhaps some of you were starting to dream of spring! Of course, we very much have a majority of the winter season yet to come and the near term forecast has the coldest air of the season arriving this very weekend. Today's featured chart checks in on the observed temperature range during January for Ames. The top panel shows the yearly maximum high temperature, middle panel presents the minimum low temperature, and finally the bottom panel shows the difference between the two (the range). Each dataset is fit with a simple average and a trailing 30 year average. Thanks to the lack of significant warmth and cold this year, the range is currently near the lowest of what has been observed on record. January is only half over, so there is plenty of time for each extreme to be exceeded and the range increased.
Voting: Good - 9 Bad - 18
Generate This Chart on Website
Mon Jan 20, 2025
Weekend Dive
20 Jan 2025 05:29 AM
The featured chart presents a meteogram of observations for the Ames Airport on Friday though Sunday. After reaching near 50°F on Friday, temperatures took a dive through the weekend with highs only in the single digits on Sunday. The cold temperatures combined with a strong northerly wind to create dangerous wind chill values, which prompted offices like NWS Des Moines to issue their first Cold Weather Advisory. The good news is that temperatures will warm this week, but only to levels slightly above freezing.
Voting: Good - 7 Bad - 0
Generate This Chart on Website
20 Jan 2025 05:29 AM
The featured chart presents a meteogram of observations for the Ames Airport on Friday though Sunday. After reaching near 50°F on Friday, temperatures took a dive through the weekend with highs only in the single digits on Sunday. The cold temperatures combined with a strong northerly wind to create dangerous wind chill values, which prompted offices like NWS Des Moines to issue their first Cold Weather Advisory. The good news is that temperatures will warm this week, but only to levels slightly above freezing.
Voting: Good - 7 Bad - 0
Generate This Chart on Website
Tue Jan 21, 2025
Expansive Winter Headlines
21 Jan 2025 05:21 AM
A very robust and large area of cold air has a tight grip on most of the contiguous US this Tuesday morning. The featured chart presents an unofficial IEM accounting of NWS headline statistics presently active. For each headline, a population estimate is presented along with a list of impacted states and the number of counties/forecast zones affected. The spatial extent of the cold can be readily seen with alerts like Winter Storm Warning shown in Louisiana and Florida along with Extreme Cold Warnings from Minnesota to Florida! While not shown on this top 10 listing, a Blizzard Warning was issued this morning by Lake Charles, Louisiana for locations along the gulf coast! For Iowa, we are dealing with very cold air temperatures and wind dropping wind chill readings to below -30°F for much of northern Iowa.
Voting: Good - 17 Bad - 22
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21 Jan 2025 05:21 AM
A very robust and large area of cold air has a tight grip on most of the contiguous US this Tuesday morning. The featured chart presents an unofficial IEM accounting of NWS headline statistics presently active. For each headline, a population estimate is presented along with a list of impacted states and the number of counties/forecast zones affected. The spatial extent of the cold can be readily seen with alerts like Winter Storm Warning shown in Louisiana and Florida along with Extreme Cold Warnings from Minnesota to Florida! While not shown on this top 10 listing, a Blizzard Warning was issued this morning by Lake Charles, Louisiana for locations along the gulf coast! For Iowa, we are dealing with very cold air temperatures and wind dropping wind chill readings to below -30°F for much of northern Iowa.
Voting: Good - 17 Bad - 22
Generate This Chart on Website
Wed Jan 22, 2025
Yearly Min Wind Chill
22 Jan 2025 05:30 AM
Temperatures continue to rebound after bottoming out Tuesday morning with unpleasant combination of bitter cold temperatures and a brisk wind. The wind chill reading at the Des Moines Airport reached a minimum of -32°F at about midnight, based on the hourly observations. The featured chart presents the yearly seasonal minimum wind chill reading, using the present day equation, for Des Moines. This year's value is slightly above the previous two years and the top panel indicates that roughly 70% of previous years have had a colder reading.
Voting: Good - 17 Bad - 0
Tags: windchill
Generate This Chart on Website
22 Jan 2025 05:30 AM
Temperatures continue to rebound after bottoming out Tuesday morning with unpleasant combination of bitter cold temperatures and a brisk wind. The wind chill reading at the Des Moines Airport reached a minimum of -32°F at about midnight, based on the hourly observations. The featured chart presents the yearly seasonal minimum wind chill reading, using the present day equation, for Des Moines. This year's value is slightly above the previous two years and the top panel indicates that roughly 70% of previous years have had a colder reading.
Voting: Good - 17 Bad - 0
Tags: windchill
Generate This Chart on Website