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 2019

Tue Oct 01, 2019
Too hot for September 30
01 Oct 2019 04:55 AM
Nothing like feeling like the middle of summer during the last day of September. Temperatures warmed well into the 80s and dewpoints were not far behind in the lower 70s. The heat index unofficially reached a muggy 92 degrees for Des Moines based on available hourly reports. The featured chart depicts the warmest heat index values on record for the site for the period between 30 September and 31 December based on IEM archives of hourly reports. All of this heat and humidity will help to drive two days of impressive rainfall totals over Iowa to start off October.
Voting: Good - 16 Bad - 0

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Wed Oct 02, 2019
Recent Monthly Precip
02 Oct 2019 04:59 AM
October has quickly picked up where September left off with heavy rainfall falling over much of the state again. September finished above average for precipitation for Ames with the featured chart showing the frequency of a month having above average precipitation over the past 30 years. The average is computed over the period of record data. It is interesting to note the differences between the months with January being much below the other months. April also stands out as wet springs have been the norm recently.
Voting: Good - 12 Bad - 0

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Thu Oct 03, 2019
Water Year Accumulation
03 Oct 2019 08:35 AM
The water year is typically defined as the 1 October through 30 September period as by 1 October most crops growing are done for the year and any additional precipitation goes toward reserves for next growing season. We recently crossed 1 October and so we can now look back on the 2019 water year. The featured chart presents the accumulated precipitation for Ames. It is interesting to note how before this summer we were on track with the wettest water year on record (1993), but the dry weather put us well behind the total from that year. The 2020 water year has started off extremely wet, so maybe we will take another run at having the wettest water year on record over the next year.
Voting: Good - 13 Bad - 0

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Fri Oct 04, 2019
Avoided frost today
04 Oct 2019 08:22 AM
The featured map presents an analysis of minimum temperature this morning based on hourly NCEP Real Time Mesoscale Analysis (RTMA). Of course, the actual minimum temperature was likely slightly lower than what is plotted here due to only having data samples every 60 minutes for this analysis. The point of the map is that we avoided frost this morning after some concern of having such cold temperatures. The first two weeks of October are typically when freezing temperatures first occur for the fall season for the state.
Voting: Good - 14 Bad - 0
Mon Oct 07, 2019
Transition to more Northerly
07 Oct 2019 05:34 AM
The featured chart presents the monthly average wind speed and wind direction for Ames based on period of record data for the site. The average wind direction is computed by vector averaging the wind speed components. It is interesting to see the wind direction cycle from southerly during the summer months to northerly during the cold season. Since Iowa is well far away from significant bodies of water, our temperatures are often heavily influenced by the source region of the air mass currently visiting the state. The wind direction gives a good first guess as to where the air is coming from. The first half of this week will be very pleasant thanks to southerly winds present.
Voting: Good - 12 Bad - 0

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Tue Oct 08, 2019
Perfect Fall Weather
08 Oct 2019 05:34 AM
The weather on Monday was near fall perfection for Iowa with highs generally in the 70s, light winds and low humidity. The featured chart presents the daily probability of having a high temperature in the 70s, a daily average wind speed below 10 MPH, and a maximum dew point below 50 based on available hourly observations for Des Moines. The black line represents the combined frequency of all these three parameters. This combination is generally limited by elevated humidity levels during the summer season and cooler temperatures during the cold season. This is the time of year for this combination, so enjoy it while it lasts!
Voting: Good - 3 Bad - 0

Tags:   perfect   fall   combo  
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Wed Oct 09, 2019
Corn Grain Drydown Calculator
09 Oct 2019 05:35 AM
The featured image is a screen capture from a new Corn Drydown Calculator tool that the IEM partnered with the FACST team here at ISU Agronomy to create. You provide the tool with a location, date, and observed corn grain moisture. The tool uses historical data for that location along with a forecast to predict the drydown of the grain. Corn moisture remains high yet for most fields and while the last few days have been ideal for drying, the forecast is not great with colder and wetter weather expected. Strong winds for the weekend are also a concern for increased corn stalk lodging.
Voting: Good - 6 Bad - 0

Tags:   corn  
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Thu Oct 10, 2019
Impending Temperature Crash
10 Oct 2019 05:35 AM
The featured chart is taken from the excellent BUFKIT Warehouse website, which utilizes a few IEM provided web services to drive its data displays. The chart shows a spaghetti plot of various forecasts for apparent temperature over the coming days. There are some weather geek attributes to this plot, but the rapid drop in temperature is readily seen starting this evening. It will go from feeling like the 60s to the low 30s and even 20s by Friday morning. Very gusty winds will be present on Friday and Saturday.
Voting: Good - 7 Bad - 0

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Fri Oct 11, 2019
Big 24 Hour Drop
11 Oct 2019 05:34 AM
A well advertised cold front has created a significant regime change over much of the United States. The featured map depicts the largest change in temperature over a 24 hour period based on hourly HRRR forecast model analyses. Eastern Colorado is the winner on this map as their temperatures went from the 80s on Thursday to the 20s and 30s on Friday. The storm system associated with the front is also dumping significant amounts of snow to our north and west, but only light flurries are expected over Iowa if anything. Freezing temperatures for Iowa are expected Friday night into Saturday morning.
Voting: Good - 18 Bad - 1
Mon Oct 14, 2019
Widespread First Frost/Freeze
14 Oct 2019 05:33 AM
The featured map displays an analysis of minimum hourly NCEP high resolution temperatures since last Thursday. A significant portion of the upper Midwestern US experienced its first sub freezing temperature of this fall season. This analysis has only a small sliver of far southeastern Iowa not breaching 32 degrees. Maps like this one also routinely show the moderating effects of the Great Lakes. Locations near the lakes and downwind will benefit with warmer near surface air temperatures this time of year.
Voting: Good - 15 Bad - 1
Tue Oct 15, 2019
Freeze Warning Timing
15 Oct 2019 05:36 AM
The widespread frost / freeze this past weekend was an interesting event. It is rare that the first significant frost event was so widespread over the state and also for a Freeze Warning to cover such a large portion of the country. The featured chart presents a histogram of the timing of the Freeze Warning product issued by NWS Des Moines. This recent event started at an abnormal time of 10 PM. This timing is a testament to how the cold temperatures were being driven by cold air advection into the state. Typically, the first events are driven by radiational cooling and as such are more isolated to the late overnight hours after a long period of cooling has happened overnight.
Voting: Good - 10 Bad - 0

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Wed Oct 16, 2019
Bigger Drops to Come
16 Oct 2019 05:34 AM
The featured chart displays the largest drop in minimum low temperature over the previous coldest temperature accumulated after 1 July until the end of the year. The 2019 value of seven degrees is highlighted for Ames and is one of the smallest on record, but there is still plenty of year to go, so one would expect to see a larger drop upcoming. The point of the plot is to gauge how quickly we can drop down in temperature. Given the current coldest value of 27, perhaps our next coldest temperature could be some 10 to 15 degrees colder than that. The present near term forecast does not indicate such an event is possible.
Voting: Good - 10 Bad - 0

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Thu Oct 17, 2019
First Half of October
17 Oct 2019 05:34 AM
Just over the first half of October is in the books and we have started off the month chilly. The featured chart displays the average high temperature for the first 16 days of the month for Des Moines for each year on record. This year comes in at about the 95th percentile (~5 percent of years colder than this one), but it is still warmer than last year! You may recall that much of Iowa had already seen measurable snow by this date last year! The good news is that the forecast continues to be mostly dry with warmer temperatures, which are both desperately needed to help crop harvest to make progress.
Voting: Good - 10 Bad - 0

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Fri Oct 18, 2019
October Hours below Freezing
18 Oct 2019 05:34 AM
Much of the western Midwest has already seen plenty of sub freezing weather this October. The featured map displays the number of hours below freezing based on the hourly NCEP RTMA. This analysis is very high resolution and nicely shows the impact of various water bodies, including the Missouri River in South Dakota. Much of Iowa is analyzed between 12 and 24 accumulated hours thus far. The weather forecast has temperatures above freezing for most of the state for the coming seven days.
Voting: Good - 22 Bad - 0
Mon Oct 21, 2019
Accumulated 65 degree days
21 Oct 2019 05:33 AM
For Des Moines, the high temperature on Sunday reached 66 degrees. The featured chart displays the year to date accumulated number of days with a high temperature of at least 65 degrees. This year's total is just short of a long term average for the site. The upcoming flat lining of this chart in November and December portends the general lack of such days in the near future. The forecast for this week has us generally in the 50s.
Voting: Good - 10 Bad - 0

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Tue Oct 22, 2019
High Wind Warning
22 Oct 2019 05:34 AM
The NWS issued a High Wind Warning over much of northwestern Iowa overnight due to forecast winds gusting to 60+ MPH. This alert is one of the rarer ones issued by the NWS and the featured map presents the yearly frequency of such a warning by county. The favored area for this warning type is clearly shown over northwestern Iowa. This area is characterized by flat and mostly tree free ground on the Des Moines Lobe and Northwest Iowa Plains, which helps to reduce friction effects that will slow near surface wind speeds down. The area is also closer to preferred locations for rapidly deepening surface cyclones over the Great Plains and locations north of the state. Far southern and southeastern Iowa are more hilly and tree covered, both working to reduce wind speeds.
Voting: Good - 15 Bad - 0

Tags:   nws  
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Wed Oct 23, 2019
Wettest First Three Weeks of October
23 Oct 2019 05:34 AM
To say that it has been wet this October would be a bit of an understatement. The featured chart displays the total precipitation for Des Moines between the period of 1 and 22 October each year. For this 22 day period, the total precipitation is, by far, the wettest on record. The total is a full inch above the next closest year! The forecast has a few chances to add to this total and perhaps break the October record of 7.29 inches (1941).
Voting: Good - 14 Bad - 0

Tags:   oct19  
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Thu Oct 24, 2019
Another Late Soybean Harvest
24 Oct 2019 05:34 AM
A late maturing crop and persistently wet weather has put the harvest of the soybean crop behind schedule. The most recent update from the USDA had just under half of the Iowa Soybean crop harvested. The featured chart presents the yearly progression of soybean harvest for Iowa with the white 'X' denoting where this year's most recent value of 48% resides for that given previous year. Excluding the brutal fall season of 2009, the past two years and this one have all had slower harvests than anything since 1986!
Voting: Good - 10 Bad - 0

Tags:   nass   soybean  
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Fri Oct 25, 2019
Humid September
25 Oct 2019 05:36 AM
The featured chart presents the daily climatology for Ames of daily average mixing ratio (a measure of humidity) along with this year's values and a departure from a simple average (bottom chart). The month of September certainly sticks out for the elevated humidity levels with nearly the entire month well above average. October has seen less humid levels, but that is also a function of the cooler air temperatures that have been prevailed for the month. Cooler air has a lower water holding capacity, which the main driver for the yearly signal shown with the climatology.
Voting: Good - 12 Bad - 0

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Mon Oct 28, 2019
Recent Monthly HDDs
28 Oct 2019 05:34 AM
October looks to end this in a frigid manner with highs some days struggling in the 30s! The featured chart displays the computed monthly heating degree days for Des Moines. The total so far for this October is about to surpass last year's total. The chart also presents the harsh reality that our cold season is just getting started and the HDD totals for November are typically at least twice as much as October. Along with the cold this week, we will have chances of snowfall. For those that have yet to purchase a Halloween costume, going as a snowman / snowwoman may work out this year.
Voting: Good - 10 Bad - 0

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Tue Oct 29, 2019
First Trace of Snowfall
29 Oct 2019 05:35 AM
The first round of snowfall fell overnight with very light totals over the state. So it is likely a good time to check in on if having the first trace of snowfall is early or not. The featured chart presents the date of the first trace or higher snowfall for Ames, the number of days that snow stuck around, and the accumulated frequency of having such an event by the given date. The chart nicely shows that this first snowfall almost always does not stick around long. This is due to soil temperatures which are still generally above freezing this time of year and will work to melt any snow that falls. The next round of snow arrives tomorrow and will primarily impact southeastern Iowa with higher amounts of snow than what fell with this first round.
Voting: Good - 11 Bad - 1

Tags:   snow  
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Wed Oct 30, 2019
'19-'20 Winter Storm #1
30 Oct 2019 05:34 AM
It is time again to start tallying winter storms for the season! The unofficial requirement used on this website is for a system to produce at least two inches of snowfall or have significant impacts (ie freezing rain) somewhere in Iowa. The system Monday night qualifies as a good portion of southeastern Iowa received two to four inches. The featured map is a smoothed analysis of NWS COOP, Local Storm Reports, and CoCoRaHS reports. We'll have another winter storm today into Thursday with the highest amounts shifted slightly to the south and east of this most recent storm.
Voting: Good - 14 Bad - 0

Tags:   winter1920  
Thu Oct 31, 2019
'19-'20 Winter Storm #2
31 Oct 2019 08:21 AM
The snow producing storm systems have been frequent this week and the most recent dump of snow brought the heaviest totals to southeastern Iowa. The featured map indicates a stripe of two to six inches over the area. It is still snowing in the area at the time of this writing, so will update the map later today once more reports come in. The snow is expected to end in the area by early afternoon. Another round of snow is expected this week, but amounts are forecast to be very light.
Voting: Good - 16 Bad - 1

Tags:   winter1920  

Features for Oct 2019