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 Jun 2018

Fri Jun 01, 2018
Polar Opposites
01 Jun 2018 05:34 AM
The featured maps depict the remarkable contrast between April and May using IEM estimated climate district average temperature ranks. While April was one of the coldest on record, May was one of the warmest on record. The current outlook for June appears to continue with the heat and concerns continue to grow for drought conditions to expand and deteriorate.
Voting: Good - 17 Bad - 0
Sun Jun 03, 2018
Saturday Wake Low
03 Jun 2018 02:22 PM
On Friday evening, a powerful cluster of thunderstorms developed into a Mesoscale Convective System and moved east and south bringing some much needed rainfall to southern Iowa early Saturday morning. These systems can have an expansive area of precipitation associated with them and sometimes this area can decay quickly leading to what happened on Saturday morning, a "Wake Low". This even was captured nicely by the Mason City Airport weather station and the featured chart presents one minute interval data from the event. These events are marked by rapid drops in pressure, which drive a rapid increase in wind speed. Sure enough, the chart shows the increase in wind while the pressure continued to drop and then moderation of the wind as the pressure returned to background state condition. Strong events like these, with winds gusts over 50 MPH, tend to do damage as was the case with wind damage reported over north-central Iowa.
Voting: Good - 8 Bad - 0

Tags:   wakelow  
Tue Jun 05, 2018
Sea of Red
05 Jun 2018 05:32 AM
The weather whiplash that was our April and May deserved to be looked at some more. This featured map depicts the difference in average daily high temperature between May and April. This difference is relative to the climatological difference between the months. For example, the climatology difference for average daily high between the months for Des Moines is 11 degrees. This year the difference was 26 degrees, so the plotted value on this map would be 15 degrees. The map is attempting to illustrate how much above and beyond the change was this year, effectively normalizing the plot.
Voting: Good - 9 Bad - 0
Wed Jun 06, 2018
Largest Month to Month Change
06 Jun 2018 05:35 AM
Yesterday's feature looked into the month to month change between April and May showing the exception departure it was from the climatology. For some locations, it was more than just exceptional but the largest on record. The featured map displays the largest *positive* month to month change in average temperature. The values plotted in red indicate that this year's change between April and May was the largest on record. These areas were likely helped to achieve the record by having substantial snow cover in April depressing temperatures for the month and allowing for a larger contrast into May.
Voting: Good - 11 Bad - 3

Tags:   climate  
Thu Jun 07, 2018
Top June Hourly Rainfalls
07 Jun 2018 05:34 AM
Ames has seen more than its fair share of severe weather this year with another round of hail and strong winds late Wednesday afternoon. The storms were slow moving and brought some heavy rainfall as well. Based on hourly observations for the Ames Airport, the 1.31 inches reported during the 5 o'clock hour yesterday was one of the largest on record during June for the site. Please note that data for the site only goes back to 1996.
Voting: Good - 12 Bad - 3

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Fri Jun 08, 2018
Full Year of Drought
08 Jun 2018 05:34 AM
The drought situation in Iowa continues to be of concern as significant rains for May and June have not panned out for all parts of the state. For much of southeastern Iowa, the US Drought Monitor has maintained at least D0 status for nearly the past year. The featured map depicts the percentage of weeks since 13 June 2017 that a given area was under any classification of drought (D0 and higher). The 13 June 2017 date was chosen as it was the first significant coverage of drought last June after the rains of May 2017. So the situation this year is a bit different than last with persistent drought in the area going into the heart of the growing season. You can generate this map for other states and time periods of your choice.
Voting: Good - 12 Bad - 1

Tags:   usdm   drought  
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Mon Jun 11, 2018
Precipitation Days Bias
11 Jun 2018 05:33 AM
A climate metric you will find on this website and others is a simple summation of the number of days per month / season / year with precipitation. While this metric may seem straight forward enough, the concept of 'days' can be tricky. It turns out that there are very few platforms out there that report true calendar day precipitation that also accounts of daylight saving time. Almost all of the present day NWS COOP data reports its 'daily' total during the early morning hours while most of the automated equipment reside in standard time all year round and thus reporting summertime 'daily' totals at 1 AM. Does the reporting time of day make a difference to the number of days reported per year with precipitation? The featured chart looks into this using a long period of hourly precipitation reports from Des Moines. The blue line reports the bias against average based on a daily reporting at the given hour. The largest values shown are in the 1-2 day per year range, which amounts to about a 1% error in the yearly totals.
Voting: Good - 5 Bad - 1

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Tue Jun 12, 2018
Five Days Already
12 Jun 2018 05:34 AM
Monday was yet another muggy June day with dew point temperatures again reaching 70+ degrees for Des Moines. Based on IEM accounting of hourly reports, this makes for the fifth day this June at or above that level. The featured chart totals these days up for each June based on period of record data for the site. The overall average just about seven and with nearly two thirds of the month remaining, it seems probable that we'll well exceed that total.
Voting: Good - 6 Bad - 0

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Wed Jun 13, 2018
Week of Warnings
13 Jun 2018 05:34 AM
The featured calendar displays the daily number of Severe Thunderstorm and Tornado Warnings for Iowa so far this year. The severe weather season got off to a very slow start thanks to the cold and snowy April. Severe weather events have come more frequently in May and June with a current stretch of seven straight calendar days with at least one warning in the state. More severe weather is possible this week.
Voting: Good - 9 Bad - 0

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Thu Jun 14, 2018
D2 Returns
14 Jun 2018 07:36 AM
The just released US Drought Monitor has a small portion of southeastern Iowa now analyzed in "D2" drought classification. This introduction was mostly due to significant precipitation deficits that have accumulated over the past 60 days as shown by the featured chart combining IEM estimated two month departures and the just released drought monitor valid 12 June. It is kind of remarkable to denote the contrast in the state that has existed over this period and even the sharp gradient over northeastern Iowa. Showers and thunderstorms have been plentiful this June, but have routinely missed the driest areas of the state. Heavy rainfall is falling again this morning, but again mostly missing far southeastern Iowa.
Voting: Good - 9 Bad - 0

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Fri Jun 15, 2018
Ames Flash Flooding
15 Jun 2018 05:34 AM
Ames took a direct hit from a powerful overnight storm complex that engulfed much of Iowa Thursday morning. The featured map displays MRMS precipitation estimates for the event along with a few NWS Storm Reports. The estimates show Ames in the four to six inch range with the heaviest totals on the north and south ends of town. This rain came quickly which lead to flash flooding and numerous issues in town with stranded cars and closed roads. Flood Warnings remain in effect for Squaw Creek and South Skunk River in the area.
Voting: Good - 13 Bad - 36
Mon Jun 18, 2018
Excessive Heat Warnings
18 Jun 2018 05:33 AM
The weather knobs for heat and humidity were both turned well to the right this past weekend for much of Iowa. The combination prompted the issuance of various heat related alerts. The urban counties of Cedar Rapids, Iowa City, and Davenport got the Excessive Heat Warning, which is the highest alert level for heat issued by the National Weather Service. The featured map looks at the county based frequency of this alert based on IEM archives back to 2009. Southern Iowa is certainly more likely to see such an alert, but the alerts are not that common average one or fewer per year.
Voting: Good - 5 Bad - 1

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Tue Jun 19, 2018
Mostly Missing Driest Areas
19 Jun 2018 05:41 AM
As has been the case recently, showers and thunderstorms visited the state again on Monday but mostly missed the driest areas of the state over southern Iowa. The featured chart presents the percentage of the state with a given rainfall departure over the past 31 days based on MRMS estimates along with the areal coverage of at least one tenth of an inch on Monday. There is some hope that southern Iowa will pick up some rainfall today, but forecasts like these have tended to disappoint the area.
Voting: Good - 2 Bad - 2

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Wed Jun 20, 2018
CONUS Above Average
20 Jun 2018 05:34 AM
The National Centers for Environmental Information (NCEI) recently declared May 2018 as being the warmest May on record for the continental US (CONUS). This warmth has persisted into June with this month perhaps on track to set the record for June as well. This warm stretch got started in late April as illustrated by the featured chart. The chart depicts the percentage of NWS CLImate reporting sites over the CONUS that have had their daily high temperature above or below average. Please note that this total is not spatially weighted. The red side of the chart has been at or above 50% coverage since the first of May. The current forecast for the rest of June continues the above average temperatures for most of the CONUS, but hot weather for Iowa will likely hold off until next week.
Voting: Good - 7 Bad - 0

Tags:   2018  
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Thu Jun 21, 2018
Sunshine Differences
21 Jun 2018 05:35 AM
The featured map presents the daily averaged amount of solar radiation since the first of May. The general pattern resembles the rainfall pattern so far this growing season with the wettest areas shown with the lowest radiation totals. Of course this makes intuitive sense that increased rainfall implies increased cloudiness and thus lowered radiation. The values presented are expressed in mega-joules per day, which is a measure of total energy received. While the values shown over Iowa do not seem that far apart ranging from 18 to 24, many plants that rely on the sun's energy for growth likely notice this difference.
Voting: Good - 10 Bad - 0
Fri Jun 22, 2018
Rare Storm Motion
22 Jun 2018 05:26 AM
A pesky upper level low pressure system has been causing interesting weather these past few days. On Thursday, NWS Des Moines issued a number of Tornado Warnings for storms that were moving toward the northwest. Storms that move in that direction rarely get Tornado Warnings over Iowa. The featured chart displays a scatter plot and kernel density estimate for NWS Des Moines issued Tornado Warnings that include an analyzed storm motion. The red dots are from Wednesday's event and there is very little company for storms that have some westward moving component. The setup for storms moving in that direction to produce tornadoes is very rare in this part of the country. The chart shows the dominate storm motion of about 30 MPH from the WSW.
Voting: Good - 13 Bad - 0

Tags:   time...mot...loc   warnings   nws  
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Mon Jun 25, 2018
Plentiful GDDs
25 Jun 2018 05:34 AM
Keith Gehling denoted on Twitter that his April 25th planted corn is tasseling now in Lee County. So much for the saying, "knee high by the fourth of July". Anyway, the featured chart presents accumulated Growing Degree Days (GDD)s for Fort Madison (in Lee County) since the planting date. This year's accumulation is near the top of the historical range. The current value above 1200 GDDs certainly agrees with corn in the tasseling stage.
Voting: Good - 11 Bad - 0

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Tue Jun 26, 2018
Quite The Reversal
26 Jun 2018 05:43 AM
It continues to be amazing to review the contrast between our weather during April and that of May and June. The featured chart depicts daily low temperature departures from average. April is shown nearly all below average while the past two months have been nearly all above average. The forecast looks to continue this pattern with warmer and more humid conditions expected to close out June and start of July.
Voting: Good - 9 Bad - 0

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Wed Jun 27, 2018
Filling the Profile
27 Jun 2018 05:45 AM
The featured chart attempts an accounting of how much of the recent rain has gone into soil. There are caveats galore with this type of analysis as there are only three soil sensors that are being extrapolated to cover a depth between six and thirty inches. The bars represent the change in daily soil water with the daily precipitation values labelled and the top chart showing the overall soil water depth in the aforementioned layer. The recent rains have built up the soil water content, this reserve may come in useful if our weather turns hot and dry.
Voting: Good - 6 Bad - 1

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Thu Jun 28, 2018
Heat Advisories
28 Jun 2018 05:36 AM
Heat Advisories are up for a good portion of the middle US with very hot and muggy conditions expected. Of course, the calendar is almost July so one would expect to see hot and humid weather, but even so heat index values are expected to be well above 100 degrees which is not your ever-day summer weather. The featured chart looks at the period each year between the first and last issued Heat Advisory by NWS Des Moines since 2006. This year got off to an early start to pick up where the late finish of 2017 ended with.
Voting: Good - 8 Bad - 0

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Fri Jun 29, 2018
Cloudy June
29 Jun 2018 05:40 AM
A thunderstorm complex rolled through Iowa Thursday morning bringing high winds and some hail. It also brought plenty of clouds creating for yet another day this June with more clouds than sunshine. This observation is quantified by the featured chart showing the frequency of having the noon observation at the Des Moines Airport reporting overcast conditions. This June is well above period of record average and a vast departure from the previous two years (bottom chart). The clouds on Thursday did save much of Iowa from baking in the heat, but the same may not be said for Friday with more sunshine expected and very hot temperatures.
Voting: Good - 6 Bad - 0

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Features for Jun 2018