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 May 2021

Sat May 01, 2021
Hot and Dry Combination
01 May 2021 08:35 PM
Iowa's weather on May Day 2021 was nothing short of exceptional with hot temperatures and low dew points. The combination of high temperature and low dew point was unprecedented for some Iowa sites as shown by the featured table. The table presents the hourly maximum temperature report, the dew point at that hour for May 1, 2021 and then the previous number of hours on record and the most recent date with a comparable combination (having at least as warm a temperature and as low a dew point). The dry April contributed to this combination as dry soils heat more quickly and don't have available water to transpire into the atmosphere which would boost dew pionts. It was also very windy making for dangerous fire weather conditions. May Day was basically "High Plains" summer weather visiting Iowa!
Voting: Good - 21 Bad - 2
Mon May 03, 2021
Complex Pattern
03 May 2021 08:23 PM
The past two days have seen much needed rain fall over parts of the state with isolated areas receiving upwards of two inches, but some parts continue to miss out. The featured map presents the number of days needed to accumulate an inch of precipitation. Areas in blue are the ones that received significant rainfall over the past two days, while a big chunk of northern Iowa is in the 30 to 50 day range. The pattern is complex though with fine scale differences showing up within individual counties. Such timely rainfall differences can sometimes lead to crop production differences on the same scale. Fields that are already planted and got the recent rainfall are going to be much better shape initially than those that did not.
Voting: Good - 18 Bad - 1

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Tue May 04, 2021
Great Soybean Planting Progress
04 May 2021 08:57 PM
Once we got past a bit of a cool stretch during April, farmers have had plenty of field workable days with warm enough temperatures and little to no rainfall. The weekly USDA NASS update for Sunday reflects that with both corn and soybean acres planted well above average. The featured map presents the USDA estimated percentage of soybean acres planted and the departure in percentage points from a recent ten year average. Most of the Midwestern US is shown ahead of average, which is generally good but rainfall is also needed.
Voting: Good - 13 Bad - 0

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Wed May 05, 2021
New Climate Averages
05 May 2021 08:35 PM
To great fanfare, the National Centers for Environmental Information (NCEI) released its updated climate averages dataset yesterday. This dataset is refreshed every ten years summarizing the weather over the past 30 years. This dataset has many components to it, but the common one folks want to know is the average daily high and low temperature. The featured chart presents a comparison of the last three versions of the NCEI daily climatology for Des Moines during May along with an IEM computed simple daily average over the current 1991-2020 period. The NCEI climatology is more involved than a simple daily average and has various smoothing functions applied along with more rigorous quality control. The 1971-2000 dataset only had values in whole degree Fahrenheit, which is why it appears more choppy than the other values shown. Anyway, you will find various IEM apps now using this updated dataset and the NWS as well now uses it to express what today's averages are.
Voting: Good - 10 Bad - 0

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Thu May 06, 2021
Trailing 60 Days
06 May 2021 10:23 PM
The generally dry weather over much of the state this spring season continues to be of great concern. This is typically a wet time of year and a period that helps charge soil moisture for the ongoing growing season. While the dry weather has allowed great planting progress over the state, the planted seeds may be just sitting there awaiting moisture and warmer weather. The featured chart presents trailing 60 day precipitation percentage of average for Des Moines. Each day of the year is colored by its respective trailing 60 day departure value. The first 15 years of the chart show little in the way of May dryness, but the last seven years are telling a bit of a different story. The near term forecast has chances of rainfall, but continued not-that-warm temperatures, so perhaps some of the planted seed will continue to wait.
Voting: Good - 4 Bad - 1

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Features for May 2021