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 Mar 2019

Fri Mar 01, 2019
Rare March Sub-10 High
01 Mar 2019 05:34 AM
Very cold air is forecast to invade the state this weekend and make for a bitterly cold Sunday and Monday. The current NWS forecast has the high temperature failing to reach 10 degrees on both days. The featured chart presents the March daily frequency of having a sub 10 degree high temperature for Des Moines. The number labels above each bar are the number of years this situation has happened for that day of the month. The overall frequency makes this occurrence about once every 20 years with the last event happening in 2014.
Voting: Good - 17 Bad - 1

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Mon Mar 04, 2019
Bitter March Wind Chills
04 Mar 2019 05:35 AM
Even with the calendar now into March, winter is not quitting with additional rounds of light snowfall over the weekend and very bitter wind chills on Sunday and now into Monday. The featured table displays the hourly wind chill temperatures for Des Moines along with the most recent March date with a colder wind chill temperature. Note that all these wind chill values were computed with the present day formula. The 8 PM reading of -21 was the coldest that the IEM has on record for the site at that hour for March. The weather this week looks to continue the winter pain with only slightly above freezing temperatures this coming weekend to look forward to, but along with it will come more snow.
Voting: Good - 11 Bad - 1

Tags:   mar19  
Tue Mar 05, 2019
9 Degree Beat
05 Mar 2019 05:34 AM
Monday was just another early March day feeling like the coldest part of winter with record cold lows and cold highs set for the day. Dubuque only made it to 5 degrees for a high, which shattered the previously coldest high for the date of 14 degrees set back in 1978. The record was broken by nine degrees! The featured chart presents the record beat margin for daily coldest high temperatures and warmest low temperatures for the site. The nine degree beat yesterday isn't even the largest this year with a 13 degree beat shown on 30 January!
Voting: Good - 10 Bad - 3

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Wed Mar 06, 2019
Frozen Stretch
06 Mar 2019 05:34 AM
Warmth has been difficult to come by this March which continues the cold that plagued most of February. Based on an hourly analysis of temperature from NOAA, the featured map depicts the number of days since the last 32+ degree Fahrenheit air temperature. Iowa is analyzed in the 1 to 30 day range with the longest stretch shown in far northwestern Iowa. Longer stretches can be found to our north with much of Minnesota in the 50 to 60 day range. Much of that area has been below freezing since the first week of January. The forecast does have some above freezing temperatures for much of Iowa this coming weekend, but it will come with another powerful storm system.
Voting: Good - 17 Bad - 1
Thu Mar 07, 2019
Reversed Snowfall Departures
07 Mar 2019 05:34 AM
The featured chart presents the season to date snowfall departures for first-order sites reported by the NWS. The chart shows the reversal that happened for most sites in the state going from negative departures in mid January to large positive departures by late February. The only hold out for this plot is Sioux City, which is currently a few inches below long term average. The first of two snow storms will impact southern Iowa today with the major storm this weekend bringing the most snow to northwestern Iowa, so Sioux City should join the rest of the state in positive territory.
Voting: Good - 11 Bad - 1

Tags:   winter1819  
Fri Mar 08, 2019
'18-'19 Winter Storm #20
08 Mar 2019 08:17 AM
Winter continues to roll along with the most recent storms being rather tame and only bringing light amounts of snowfall to the state. The arbitrary threshold of having at least two inches of snowfall reported to qualify for an "IEM Winter Storm" map was barely exceeded with yesterday's snowfall. A few isolated reports of three inches were made, but totals were generally around two inches or less. A powerful storm arrives for the weekend, but the location of the heaviest snowfall totals looks to be north of Iowa.
Voting: Good - 13 Bad - 1

Tags:   winter1819  
Sun Mar 10, 2019
'18-'19 Winter Storm #21
10 Mar 2019 01:01 PM
Our most recent winter storm brought mostly rain to the state, but portions of northern Iowa got a mix of freezing rain and snow. The featured map presents available snowfall reports from COOP and CoCoRaHS observers. Strong winds again caused travel troubles in the area due to blowing snow and some melt / re-freezing. Road conditions over the area with snowfall remain poor this Sunday afternoon. Concern continues to grow over the amount of snow and ice we have accumulated on the ground presently combined with upcoming rainfall and snowmelt events. The next big storm event arrives on Tuesday, but temperatures are expected to dramatically warm well above freezing. Such a combination can result in ice james.
Voting: Good - 4 Bad - 0

Tags:   winter1819  
Mon Mar 11, 2019
February High Temps
11 Mar 2019 05:33 AM
The cold of February has mostly continued into March along with the frequent snow producing storms. The featured chart looks back on the distribution of average daily high temperatures for the month among long term climate sites in the state. The overall climatology over all years is shown as well for comparison. Nearly all of the distribution for 2019 is shown colder than the simple average of climatology, but the distribution is tight and does not necessarily exceed the minimum extremities of climatology. The first pass reasoning for this is persistent snow cover that helps to keep sites below freezing and the persistent storms which provide moisture and clouds to help keep temperatures from getting too cold.
Voting: Good - 10 Bad - 0

Tags:   feb18  
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Tue Mar 12, 2019
Low Water Stress
12 Mar 2019 05:34 AM
The featured chart depicts trailing 90 and 180 day arridity index for Centerville (southern Iowa). This index combines the impacts of temperature and precipitation departures. The chart shows a different situation going into this year's growing season than last year. Last year was near neutral during early March while this year is extremely low water stress. The large negative numbers are a result of a cold and very wet winter season. Getting soils warmed up and dried out may be a struggle this spring.
Voting: Good - 9 Bad - 0

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Wed Mar 13, 2019
Finally Breaking the Streak
13 Mar 2019 05:34 AM
Finally, some semblance of warmth has returned to much of the Midwestern US. High temperatures on Tuesday were above average for some locations over this area, which ended extended streaks of consecutive days below average. The featured map presents an accounting of these streaks valid through Tuesday. Values plotted in both and as negative numbers represent current streaks of days with the high temperature below average. The numerous red ones show the sites that finally made it above average on Tuesday for the first time in a while. Even warmer conditions are expected on Wednesday to likely end many of the other below average streaks on this plot. This warmth combined with heavy rainfall on deep snow pack, frozen soils, and ice covered rivers are going to create a flooding mess over the region.
Voting: Good - 22 Bad - 0

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Thu Mar 14, 2019
Pressure Changes
14 Mar 2019 05:43 AM
The surface low pressure center of the massive storm system impacting much of the country is moving into Iowa this morning. Those that are sensitive to changes in air pressure will certainly notice its passing. The featured plot looks at the frequency of 24 hour pressure changes for Des Moines based on the mean sea level pressure value. Having large day to day changes are certainly more common during the cold half of the season. Such large and powerful storm complexes need to have strong contrasts in surface temperature, so it makes sense that these systems are rarely found during the warm season.
Voting: Good - 14 Bad - 0

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Fri Mar 15, 2019
Breaking the Blue Streak
15 Mar 2019 05:32 AM
While the major storm system this week brought high winds, rain, fog, and a blizzard to folks north and west of Iowa, it also brought some warm air to the state. The featured chart shows daily high temperature departures for Sioux City. The days below average are colored blue and the chart nicely shows that our recent two days of warmer temperatures finally broke the long running streak of below average since early February for the site. This sudden warm-up and rain has a downside though with widespread flooding now due to frozen soils and ice jams. The good news is that the next week looks mostly dry with above freezing daily high temperatures.
Voting: Good - 18 Bad - 0

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Sun Mar 17, 2019
'18-'19 Winter Storm #22
17 Mar 2019 08:51 PM
A quick moving system dumped a narrow swatch of graupel, snow, and slop over east central Iowa Saturday night into Sunday morning. The featured analysis shows a narrow band of two to four inches stretching from Cedar Rapids to just north of Davenport. Much of this snow did not survive the mid-March sunshine on Sunday. The big story in the state continues to be the flooding and hopefully a mostly dry week is in store to help with the situation.
Voting: Good - 7 Bad - 1

Tags:   winter1819  
Mon Mar 18, 2019
Historic Missouri River Flooding
18 Mar 2019 03:43 PM
The featured image is courtesy of @CopernicusEU showing a dramatic view of the historic flooding over eastern Nebraska and western Iowa using data from Sentinel 2 satellite. For the gauge at Plattsmouth, Nebraska, the Missouri River is four feet above the previous record stage. The ongoing flooding situation is being helped by mostly dry weather this week, but there is still plenty of snow to melt yet over areas further north.
Voting: Good - 5 Bad - 0

Tags:   flood   satellite  
Tue Mar 19, 2019
Awaiting First 60
19 Mar 2019 05:32 AM
Having the early part of the winter season be not all that bad is a forgotten memory against the past month or so of full scale winter. The weather has straightened out now and is starting to feel more like spring time. Much of the state though is still awaiting the first 60+ degree temperature of the year. For Ames, the featured chart presents the period between the first spring date and last fall date each year with the high temperature of at least 60 degrees. The simple average is shown as well and indicates we are a few weeks behind schedule. The forecast for the upcoming weekend has optimism that Ames will finally reach 60 degrees.
Voting: Good - 8 Bad - 0

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Wed Mar 20, 2019
This Winter
20 Mar 2019 05:16 AM
The featured chart presents a time series of temperature and precipitation departures for Ames since early November. The departures are expressed in terms of standard deviation (sigma) and evaluated every 14 days. The arrows connect the time series and these type of plots often cycle due to the time window averaging. Anyway, the plot shows how this winter has progressed from mild and dry to extremely wet and cool. Our current status is bringing us back to near average temperatures while noticing the rain events from last week. The forecast continues to be optimistic for warmth and limited rainfall, both of which we need.
Voting: Good - 7 Bad - 0

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Thu Mar 21, 2019
Spring Already Started
21 Mar 2019 05:09 AM
On Wednesday afternoon, the spring season officially started with the vernal equinox. Of course, the spring season is an arbitrary period of time that can be defined a number of ways. One such way is to define it as the period starting after the coldest 91 day stretch of days. The featured chart presents such an analysis and shows that for Ames, this coldest period ended on 8 March. Irregardless, the warmer recent temperatures, even if only near average have felt nice.
Voting: Good - 8 Bad - 1

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Fri Mar 22, 2019
High Temp Variability
22 Mar 2019 05:34 AM
The featured chart look into the daily variability of high temperature for Des Moines based on period of record data. The top panel displays the spread of daily high temperatures expressed in standard deviation for a given day and for the day to day variability. The plot shows that this time of year has some of the highest spread for temperature (most variability). The bottom panel just presents a diagnostic looking at the relationship between the two variabilities plotted. The moral of the story is that the previous day's high temperature is a better predictor of the current days high than the average for the date.
Voting: Good - 10 Bad - 0

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Features for Mar 2019