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 Sep 2018

Sun Sep 02, 2018
Cancelled Football Game
02 Sep 2018 09:03 PM
The ISU vs South Dakota State football game got cancelled Saturday evening due to lightning. The game started on time, but was suspended shortly thereafter once lightning was detected near the stadium. The policy is for the game to resume once there has been at least 30 minutes of no lightning within 8 miles of Jack Trice Stadium. The featured chart presents the time duration since the latest lightning strike within 8 miles for the evening of the event. This analysis shows only a brief window of time just before 9 PM that this 30 minute rule requirement would have been satisfied. Otherwise, the game could have only resumed around 1 AM!
Voting: Good - 19 Bad - 1

Tags:   football   lightning  
Wed Sep 05, 2018
Record Four Day Rainfall
05 Sep 2018 05:18 AM
Rainfall totals continue to pile up and now to add insult to injury, a slug of moisture from Tropical Storm Gordon is headed our way. The featured chart shows maximum four day precipitation totals for Newton. Based on preliminary data, the first four days of this September were the wettest four on record for the site with over ten inches reported. If there is any good news in all of this, the heaviest rains over the next few days are expected to stay south of the heaviest rainfall totals that fell so far this month.
Voting: Good - 8 Bad - 1

Tags:   sep18  
Generate This Chart on Website
Thu Sep 06, 2018
September Precip Hours
06 Sep 2018 05:42 AM
Rain was again common on Wednesday as has been the case this entire September. The featured chart totals up the number of hourly reports that had measurable rainfall for the Des Moines Airport. This year's total is shown along with a long term average and the maximum monthly value. Our total this September is already above average and we are only five days into the month! The total for July sticks out as well as after the epic deluge on the evening of 30 June, the rains basically stopped for the area.
Voting: Good - 10 Bad - 1

Generate This Chart on Website
Fri Sep 07, 2018
60% of Monthly Total
07 Sep 2018 05:36 AM
The heavy rainfall events of the past week or so have thankfully subsided for now with only far southeastern Iowa expected to see much rainfall over the coming week. It will take a number of daily features to show through the rainfall totals and interesting stats from this recent event. Today's feature looks at how often a single day's precipitation total is at least 60% of the total for the month. On 28 August, Ottumwa reported 4.07 inches which was 60% of the total for the month of 6.71 inches. Having this combination is most common during the lowest precipitation months of the cold season when climatological totals are lower and individual heavy rainfall events are more anomalous.
Voting: Good - 12 Bad - 3

Generate This Chart on Website
Mon Sep 10, 2018
70+ Dew Points during September
10 Sep 2018 05:25 AM
After a very humid start to September, drier and cooler air visited Iowa. The heat and humidity are set to return this week with dew point temperatures perhaps reaching the miserable 70 degrees again. The featured chart looks at the frequency of having such warm dew points during September for Des Moines. The frequency is expressed in number of hourly reports with such a reading. Of course the 2018 total is still in progress and already well above most other years since the early 1970s.
Voting: Good - 9 Bad - 4

Generate This Chart on Website
Tue Sep 11, 2018
AP Photo
11 September 2001
11 Sep 2018 05:34 AM
The years continue to pass, but may we never forget that fateful day back in 2001.
Voting: Good - 0 Bad - 0
Wed Sep 12, 2018
Almost Back to Average
12 Sep 2018 05:12 AM
The very wet weather of late August and early September have taken a bite out of the drought conditions over far southern Iowa. The featured chart depicts year to date accumulated precipitation for Centerville (far southern Iowa) with the envelope of observed values shaded in brown and this year's value in red shown in comparison to long term average along with the most extreme years. The deficit this year was almost erased by the recent rains. The weather has turned drier and warmer this week, so it will take more rainfall later this fall season to erase.
Voting: Good - 11 Bad - 0

Generate This Chart on Website
Thu Sep 13, 2018
Hurricane Florence
13 Sep 2018 05:42 AM
The eye of Hurricane Florence is now visible on the US NEXRAD composite generated by the IEM. The storm is of great concern for the southeastern US as it is expected to take its sweet time coming onshore and meander south during the process. While the maximum wind rating and thus the hurricane category has recently decreased, the storm is extremely large with a large area of tropical force winds. It will also be a prolific rainfall producer.
Voting: Good - 11 Bad - 0

Tags:   hurricane  
Fri Sep 14, 2018
landfalls based on HURDAT2 archive
Landfalling Hurricanes and Iowa
14 Sep 2018 05:34 AM
Hurricane Florence has taken its sweet time to make landfall on the eastern coast of the US. Do landfalling hurricanes impact Iowa weather? The featured chart attempts to address that question by looking at the average temperature departures and precipitation frequencies for Des Moines for a period of days relative to the landfall event. The charts are partitioned by if the hurricane made landfall on the east coast or gulf coast. While the magnitudes are small, a comparison of the impact on temperatures is interesting and would indicate that gulf hurricanes slightly boost temperatures and east coast hurricanes slightly dip temperatures. Our actual weather with Florence isn't exactly following this climatology as temperatures have been above average prior to its landfall. The impact on precipitation does not appear as obvious.
Voting: Good - 10 Bad - 0

Tags:   hurricane  
Mon Sep 17, 2018
September Flight Rules
17 Sep 2018 05:34 AM
This September has been seen two distinct periods of weather so far. The first week or so was extremely wet and now the last week or so has been bone dry and warm. The featured chart looks at the hourly flight rule status for the Des Moines airport so far this month. The two periods can be discerned with plenty of flight issues found over the first seven days and no issues since. Monday is expected to be hot and mostly dry for much of Iowa while better rain chances arriving on Tuesday and a turn to cooler conditions.
Voting: Good - 7 Bad - 0

Generate This Chart on Website
Tue Sep 18, 2018
Wilmington, NC Record Rainfall
18 Sep 2018 05:34 AM
What's left of Hurricane Florence is finally moving up the eastern US coast. It left a tremendous mess over North and South Carolina after dumping a significant amount of rain. The featured chart shows the year to date accumulated precipitation for Wilmington, NC for this year, 1999, 2007, and the observed range based on period of record data. Even before Florence, the site was already at a record accumulation. The year of Hurricane Floyd (1999) is plotted as well, as it was the previous record accumulation and whose jump in year to date total came about at the same time as Florence.
Voting: Good - 16 Bad - 1

Generate This Chart on Website
Wed Sep 19, 2018
80+ Degree Days
19 Sep 2018 05:33 AM
Tuesday was another very warm September day in Iowa until storms knocked temperatures back into the 60s and low 70s. Ames was able to reach 80 degrees again for over the 100th day this year. The featured chart displays the number of accumulated days with a high temperature of at least 80 degrees. The average line shows that by the end of September, we mostly stop accumulating days with this warm of a high temperature. The forecast expects a few more warm days before cooler weather arrives for the weekend.
Voting: Good - 10 Bad - 0

Generate This Chart on Website
Thu Sep 20, 2018
19 Sep 2018, GOES 16 ABI Channel 2 Imagery courtesy of College of DuPage
Bore + Gravity Wave Clouds
20 Sep 2018 05:34 AM
The featured animation is of GOES 16 satellite imagery over Iowa on 19 September 2018. The imagery shows some neat bore / gravity wave clouds resulting from thunderstorms during the day. These clouds are a result of rain cooled air being denser and pushing south into warmer northbound flow. The animation shows these clouds dissipating with time and a general outflow boundary / warm front appear with a thunderstorm eventually fire on the boundary over southern Iowa. Due to file size constraints, this animation does not depict the highest resolution in space and time now available by this new satellite. You can find great imagery like this on the College of DuPage website.
Voting: Good - 14 Bad - 1

Tags:   satellite  
Fri Sep 21, 2018
A month of Fall Already
21 Sep 2018 05:34 AM
The Fall Equinox is on Saturday and thus starts the astronomical fall season. The weather recently has certainly felt more like the middle of summer than early fall recently, but thankfully a cold front swept the state clean of the hot and muggy air overnight. Of course the definition of the seasons is arbitrary, but if one considers the warmest consecutive 91 day period each year as the summer season then the start date of the fall season can be determined. The featured chart does that calculation and shows that the trailing 91 day average temperature peaked back on 21 August! That means we have had a month of the fall season already! The bottom two panels show some metrics on the fall season and the average number of days shown in the bottom panel show the fall season averaging only 84 days. This weekend looks to be awesome fall weather, so enjoy it before winter comes.
Voting: Good - 8 Bad - 1

Tags:   fall  
Generate This Chart on Website
Mon Sep 24, 2018
Plenty of Warm Highs
24 Sep 2018 05:34 AM
High temperatures for the past three days have been very pleasant in the 60s and 70s, which have been difficult to come by so far this year. The featured chart counts the number of days this year, last year, and on average that the daily high temperature is in the given for the year to date period for Ames. The 50s, 60s, and 70s ranges are all below average for 2018 while the 80s and 90s are both well above average. The cold and then hot spring season this year is mostly to blame for this discrepancy. Perhaps we can make up the difference with a long and seasonable fall season in Iowa!
Voting: Good - 10 Bad - 0

Generate This Chart on Website
Tue Sep 25, 2018
Severe Season Winding Down
25 Sep 2018 05:33 AM
While a few severe thunderstorms are possible today, the severe weather season is generally winding down. The featured chart presents the frequency of having a severe thunderstorm warning in Iowa by week of the year. The top chart shows the number of years since 1986 that had at least one warning for that week and the bottom chart shows the overall number of events. The transition from September into Octobers shows the downward trend in activity with very few events found for the month of October.
Voting: Good - 9 Bad - 2

Generate This Chart on Website
Wed Sep 26, 2018
Wettest Month for Waterloo
26 Sep 2018 05:33 AM
The featured chart presents the largest precipitation totals by month for Waterloo. With just over an inch on Tuesday, the rainfall total for this September is now the largest on record for the site for any month! The 12.89 inches this month bests the previous largest total of 12.82 inches for July 1999. Having the wettest month on record be September is somewhat rare for a long term climate site in Iowa. Of the 113 long term climate sites in Iowa tracked by the IEM, a previous September was the wettest month on record for 14 of them. The most common wettest month is June (41 sites).
Voting: Good - 10 Bad - 1

Tags:   2018  
Generate This Chart on Website
Thu Sep 27, 2018
70+ in September
27 Sep 2018 05:38 AM
High temperatures today and on Sunday may reach 70+ degrees for some locations in Iowa. The featured chart presents the frequency of having such warm temperatures by day of September for Ames. The values labelled above the bar are the number of years with the given day having such a warm temperature. The overall frequency for the end of September is around 60%, so such temperatures are typical. The forecast has a warmup coming next week along with some more chances of thunderstorms.
Voting: Good - 6 Bad - 0

Generate This Chart on Website
Fri Sep 28, 2018
Wettest September
28 Sep 2018 05:34 AM
The featured map presents IEM estimated climate district ranks for total precipitation this September. Please note that these values are up until 27 September, so with three more days to go, the shown ranks could decrease further. Even after having said that, some of the districts shown are already at the wettest on record. For Iowa, that includes the northeastern district. A daily feature early this week denoted that Waterloo (sw corner of this district) had its wettest month on record for any month. The near term forecast hits this wettest area hard over the coming week with even more rainfall.
Voting: Good - 11 Bad - 0

Tags:   sep18  
Generate This Chart on Website

Features for Sep 2018