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.

Features for Oct 2021

Fri Oct 01, 2021
Low Precipitation Hours
01 Oct 2021 12:13 PM
For those of us in the western half of the state, the rainfalls of the past two days have been a remarkable departure from a very dry September. The featured chart presents the number of hourly reports of measurable rainfall from the Ames airport weather station. A simple average using period of record data is shown along with the 2021 totals and largest values on record. The 2021 total came in well below average and the smallest total since April. Chances of rainfall remain in the forecast along with pleasant early October temperatures.
Voting: Good - 10 Bad - 0

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Mon Oct 04, 2021
Warm Three Weeks
04 Oct 2021 05:38 AM
Mild temperatures continue to dominate this fall season with the featured chart presenting the average temperature since 12 September for Des Moines. The 2021 value is highlighted and about seven degrees above simple long term average. The plot shows that most of the recent years for this period has been well above average. The near term forecast continues the warm weather with highs back near 80 degrees by the coming weekend.
Voting: Good - 18 Bad - 1

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Tue Oct 05, 2021
Dense Fog Advisory Duration
05 Oct 2021 05:31 AM
The National Weather Service has a Dense Fog Advisory active for portions of north central Iowa this morning, which includes Cerro Gordo County (Mason City). The featured plot presents the distribution of advisory duration for this event type and county location. The orange line presents the duration of the advisory at issuance and the blue line represents the final duration after any extensions and/or early cancellations. Sometimes the initial advisory is expanded in time, so why the blue line is sometimes higher than the orange line. Anyway, the present advisory extends seven hours, which is right at the 50% level for frequency, which implies approximately the median value. These events tend to be limited to peak overnight cooling hours as the air temperature cools to the dew point and then "burn off" with the rising of the sun causing an increase in temperature away from the dew point.
Voting: Good - 14 Bad - 0

Tags:   densefog  
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Wed Oct 06, 2021
Partitioning of 70s
06 Oct 2021 05:30 AM
One of the common complaints about the spring and fall seasons in Iowa is that they are too short lived. Sure the fall weather is spectacular at the moment, but most are pessimistic that winter is a few mere weeks away. A confounding factor is that the seasons are not well defined as summer and winter like temperatures can both bleed into the spring and fall seasons. Many would agree that having daily high temperatures in the 70s is excellent fall or spring weather, but how commonly are these temperatures found during those seasons? The featured chart presents the partitioning of all daily high temperature observations in the 70s from Des Moines into the four seasons based on calendar months. And sure enough, the summer months barely beat out spring and fall seasons! The chart also clearly delineates that these temperatures are not found during winter, so please enjoy them now as the winter pessimists will soon be right!
Voting: Good - 14 Bad - 2

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Thu Oct 07, 2021
Rare October Combination
07 Oct 2021 05:32 AM
The weather on Wedneday had a bit of a weird feel to it with somewhat dreary skies, easterly winds, and rather muggy / warm temperatures for October. A number of places in the state were able to record the combination of winds for the northeast and temperatures in the 70s. The featured wind rose presents the frequency of wind speed and direction during October for Des Moines when the air temperature is at least 70 degrees. The plot shows not much frequency of having such a combination of temperature and wind direction for the month. Winds from the south are overwhelmingly more common as such winds often help transport warmer air into the state and thus buoy air temperatures. The near term forecast continues the warm temperatures along with some chances of rainfall.
Voting: Good - 14 Bad - 1

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Fri Oct 08, 2021
Should be first freeze time
08 Oct 2021 05:53 AM
The second week of October is about the time much of Iowa expects to have seen its first fall temperature below 32 degrees Fahrenheit as shown by the featured chart plotting the 50th percentile date. The present forecast has temperatures at much warmer levels with 80 degree highs and rather muggy conditions for October along with a number of chances for rain and thunderstorms. The featured map is a bit noisy as metrics like this are often very sensitive to local micro-climate effects as nearby stations may have different siting and local topographies.
Voting: Good - 13 Bad - 0

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Mon Oct 11, 2021
October Dew Point Percentiles
11 Oct 2021 05:35 AM
The weather over the past weekend continued the October trend of very mild and humid conditions. The featured chart presents some metrics on October dew point temperatures based on period of record archives from Dubuque. The top panel, which could use some tweaks for readability, presents the percentile values for dew point temperature by hour of the day. The bottom panel is more interesting and shows hourly dew point percentiles for each hourly report so far this month. Observed dew points for the entire month have been 90th and higher percentile range. Such high readings preclude any chance of the first widespread frost as humid conditions buoy temperatures during the night time. Our humid October does look to change later this week with more seasonable temperatures and values approaching the freezing level by next weekend.
Voting: Good - 8 Bad - 0

Tags:   oct  
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Tue Oct 12, 2021
New Daily Record
12 Oct 2021 05:37 AM
The National Weather Service issues "Daily Climate Reports" for locations including many of the major airports. The featured infographic contains the report for Monday for Cedar Rapids. The location set a daily precipitation total record of 1.49 inches besting the previous record of 0.86 inches back in 1912. While the month to date total is now well above average, the year to date total is nearly 13 inches below average! There are more chances of rain in the forecast this week before a return to drier weather arrives for next week.
Voting: Good - 13 Bad - 0

Tags:   cli  
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Wed Oct 13, 2021
Monthly Warning Counts
13 Oct 2021 05:21 AM
2021 has been a strange year for severe weather over the United States, so it makes sense that the past few days in October have seen plenty of it. The featured chart presents NWS issued tornado warnings by month since 1986. Please note that data prior to 2001 is not exactly the greatest of quality, but is the best known at this time! The October this year is already above September not too far behind the total for all of April! The warning total count this October is nothing too exceptional yet as compared with past Octobers as this month certainly can behave a lot like April with strong clashes of cold and warm/humid air masses.
Voting: Good - 20 Bad - 2

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Thu Oct 14, 2021
October Lows
14 Oct 2021 12:05 AM
Chilly overnight low temperatures have been elusive so far this October, but that looks to change over the next few days thanks to less humid air and clear overnight skies. Having warmer low temperatures during October has been somewhat of a trend over the past number of years. The featured chart presents the frequency distribution of October daily low temperatures for Des Moines during two sequential 30 year periods. The distribution is smoothed to filter out some of the noise with the two 30 year periods overlain and then differenced via the bottom chart. The most recent period has seen a slight shift in distribution with more frequent days in the 40s vs the 30s. The y-axis units are a bit hard to explain, but the larger the number indicates more frequent events. The right hand table presents the percentiles for each period with about a one degree difference shown.
Voting: Good - 10 Bad - 0

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Fri Oct 15, 2021
2021 Soybean Harvest
15 Oct 2021 05:33 AM
The soybean harvest has made good progress this fall season in Iowa. The featured chart presents an IEM attempt to produce a daily analysis of how far ahead or behind schedule the given year's harvest was compared to USDA NASS weekly crop harvest estimates. For an illustration, the most recent NASS estimate for Iowa this year was 56%, which is a few days earlier than when one would expect to hit 56% completion based on an average computed over the past fifteen years. A comparison is made to other recent and notable years like 2019, which was miserably wet and late maturing. 2012 was the drought year and had great harvest conditions along with a very early maturing crop. Recent rains have slowed progress somewhat, but drier weather looks to return to allow progress to resume.
Voting: Good - 12 Bad - 0

Tags:   nass  
Mon Oct 18, 2021
2021 Fall Min Low
18 Oct 2021 05:44 AM
The chilliest air of the season has visited the state with a number of locations experiencing their first sub 32 degree temperature. The featured map presents the minimum temperature found within the hourly Real Time Meso-Analysis (RTMA) from the NWS. The north western portion of the state has seen the coldest temperatures thus far. We'll have a few days of mild temperatures this week before cooler weather arrives on Thursday along with additional chances of having the first frost of the season for other portions of the state.
Voting: Good - 14 Bad - 0
Tue Oct 19, 2021
MOS Dew Point Forecasts
19 Oct 2021 05:32 AM
The IEM curates a few forecast datasets including the Model Output Statistics (MOS) from a few models produced by the NWS. The MOS takes forecast output from the weather models and attempts to produce bias corrected time series forecasts for point observation locations typically at the airport weather stations. The featured chart presents a qualitative comparison of the MOS output for dew point temperature for Ames along with the actual observations. The bars represent the range of forecast values at the given valid time via the ensemble of previously issued MOS forecasts for that time. Since the MOS is run multiple times per day and has a forecast out a number of days, an individual forecast time will have a range of forecasts based on that time lagged ensemble. Anyway, that chart nicely shows the roller-coaster dew point temperatures have been on this month with only a modest increase over the next few days expected. You can generate plots like these via this website for other models and airport forecast locations of your choice!
Voting: Good - 2 Bad - 0

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Features for Oct 2021