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 Dec 2018

Mon Dec 03, 2018
'18-'19 Winter Storm #6
03 Dec 2018 08:30 AM
The snow producing winter storms continue at a brisk pace with northwestern Iowa picking up the heaviest amounts from the weekend's storm system. The storm also brought significant rainfall to much of the state. The prolonged snowfall event happening over the weekend is making for a bit of a difficult snowfall analysis shown here, but another attempt will be made at generating a graphic later today once more data arrives. The forecast has this week mostly dry, so hopefully we can get a bit of a break from the snow storms.
Voting: Good - 5 Bad - 1

Tags:   winter1819  
Tue Dec 04, 2018
Just 51
04 Dec 2018 05:34 AM
Since the first of November, the warmest temperature for Dubuque has been just 51 degrees. The featured chart presents the yearly maximum high temperature between 1 November and 3 December each year. The 51 degrees this year is the lowest on record for the site. As the forecast currently stands, we have at least one more week of cold weather before perhaps seeing a warm up two weeks from now.
Voting: Good - 8 Bad - 0

Tags:   nov18  
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Wed Dec 05, 2018
Deep Snow for November
05 Dec 2018 05:34 AM
The featured chart depicts daily snow depth reports from Osceola (just south of Des Moines). Each horizontal line of data represents the given winter's reports. The bottom line represents the present winter season with boxes in gray denoting missing reports. The recent big snowfall to end November really sticks out for the site compared with all other Novembers on record. Even when considering the entire winter season, you have to go back to 2009 to find comparable snow depths.
Voting: Good - 10 Bad - 0

Tags:   snowcover  
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Thu Dec 06, 2018
40+ in December
06 Dec 2018 05:34 AM
Air temperatures were about as warm as they have been over the past two weeks on Wednesday with values briefly at 40 degrees during the afternoon hours for Des Moines. The featured chart looks at the hourly frequency of having a 40+ degree temperature during December. The afternoon odds are about one in four to five days, which is about right for having one day so far five days into December. Unfortunately, it will be at least five more days until we perhaps may see as warm of temperatures again.
Voting: Good - 7 Bad - 0

Tags:   dec  
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Fri Dec 07, 2018
December 6th Temps
07 Dec 2018 05:34 AM
The featured chart shows the high and low temperature distribution for December 6th based on long term climate reports for sites in Iowa. For both highs and lows the observed histogram is shown along with the idealized normal distribution based on the observed mean and standard deviation. It is kind of interesting to compare the idealized and actual distribution and note how the highs and lows show similar differences between the two. The mean for the low temperatures is pulled lower by the fatter tail for the coldest temperatures (typically snow cover during clear nights).
Voting: Good - 11 Bad - 0

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Mon Dec 10, 2018
Within Five Degrees
10 Dec 2018 05:33 AM
For Des Moines, the high and low temperature on Sunday was within five degrees of average. The featured chart looks into the percentage of years with either the high or low temperature within five degrees Fahrenheit of average. The chart shows that this situation is actually not common with frequencies at about 30%. Rewording and for example, on about 70% of years the daily high is outside of the +/- five degrees of average. While the values on Sunday were both below average, perhaps we will eek out a couple days this week above average.
Voting: Good - 9 Bad - 1

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Tue Dec 11, 2018
Snowfall Hole
11 Dec 2018 05:35 AM
The featured map presents total season snowfall as analyzed by NOAA NOHRSC. The analysis confirms what we in central Iowa already know, that is the snowfall hole over the center of the state exists. The big snowfall events have missed us to the north, east, and south. If you look closely, there is even one pixel analyzed at less than an inch total over Des Moines. Some precipitation is in the forecast, but nothing significant for accumulating snowfall.
Voting: Good - 12 Bad - 0

Tags:   winter1819  
Wed Dec 12, 2018
Winter Weather Advisory Counts
12 Dec 2018 05:34 AM
The Winter Weather Advisory is about the least significant headline the National Weather Service can issue for nuisance winter weather. For today, such an advisory is in effect for parts of northeastern Iowa for the threats of light freezing rain and an inch or so of snow. The featured map presents the yearly average number of such advisories per county in the state. There is a significant north to south difference with frequencies ranging from ten to near five events per year.
Voting: Good - 13 Bad - 0

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Thu Dec 13, 2018
Dry Air
13 Dec 2018 05:33 AM
The dry air so far this season has been noticeable. The featured chart presents the average dew point for Des Moines for the 1 Nov to 12 Dec period each year on record based on daily max and min observations. The average value this year comes in at about the 90% percentile, so about 1 in 10 years as low humidity as this one. If you are sensitive to dry air and prone to static discharging against anything conductive you touch, this season has not been that pleasant so far.
Voting: Good - 10 Bad - 0

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Fri Dec 14, 2018
50 Degree Percentiles
14 Dec 2018 05:34 AM
Much warmer temperatures are expected over the next few days and perhaps we could eek out a 50 degree temperature. Such warm days have been difficult to come by since the first of November with only four days reaching that level for Des Moines. The featured chart looks at the monthly percentiles and return intervals for having a daily high temperature of at least 50 degrees. For December, the average is just over three days for the month while November is over ten days. The chances for such warm days decreases in January, so lets hope we can enjoy the 50s again this winter season.
Voting: Good - 10 Bad - 0

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Mon Dec 17, 2018
Clear Skies and Temps
17 Dec 2018 05:33 AM
For those without snowcover, temperatures warmed very nicely over the weekend into the 40s and even briefly the 50s for a lucky few. Those with out snow were likely crediting the clear skies for allowing sunshine to warm us up, but the impact of clear skies on temperature is not straight forward this time of year. The featured chart presents the temperature difference between when skies were reported clear versus the period of record observations by week of the year and local hour of the day. The chart shows that having sunshine has the largest warming during the warmer half of the season. This is due to more direct insolation during periods closer to the summer than winter. During the winter time, things like snow cover and which air mass is currently visiting the state are more important to determine our temperatures. The chart also nicely shows that the impact during the night time hours is almost always negative (cooler) as the absence of clouds allow long wave terrestrial radiation to escape.
Voting: Good - 11 Bad - 2

Tags:   clouds  
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Tue Dec 18, 2018
Temperatures Above Us
18 Dec 2018 05:34 AM
Temperatures warmed nicely on Monday with highs in the 40s for those without significant snow cover. Do warm surface temperatures translate to warm temperatures aloft? The featured chart presents December temperature percentiles for mandatory sounding pressure levels from the Omaha site on Monday night. Values of 100 would indicate the warmest on record for the site. Please recall that pressure decreases with height, so the first value shown at 925 mb is the closest to the surface. So indeed the levels nearest to the ground are warm as well, which makes sense as this is the air that mixes to the ground during the day. But as you go up higher in the atmosphere, temperature percentiles go down until rapidly increasing again above the tropopause. The explanation is a bit complex, but likely involves the 400 to 50 mb levels being anonymously high due to the warmer lower atmosphere and thus colder temperatures near the tropopause.
Voting: Good - 8 Bad - 1

Tags:   sounding  
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Wed Dec 19, 2018
Warmest Day of December
19 Dec 2018 05:34 AM
Temperatures continue to creep higher on Wednesday with highs making it into the mid 50s for Des Moines and setting the warmest temperature so far this December. The featured chart looks at the frequency of a given day of December having the warmest high or low for the month in a given year. Having the warmest high on 18 December is nothing that exceptional as about each day of the month having an equal chance after the first four days of December. Sadly, the forecast has temperatures creeping colder again and not much hope for a white Christmas yet.
Voting: Good - 6 Bad - 0

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Thu Dec 20, 2018
No Precip Since Second
20 Dec 2018 05:34 AM
For Ames, December got off to a very wet start with over an inch reported on the first and just a few tenths on the second. It has been dry since then and looks to remain that way into at least next week. The featured chart looks at the accumulated precipitation totals for the site for this year, climatology, and the range of observed values based on the nearest climatological site for Ames. Even with not having precipitation since the second, the month to date total is still well above average.
Voting: Good - 10 Bad - 0

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Fri Dec 21, 2018
Above Zero Min Wind Chill
21 Dec 2018 05:34 AM
The warmth of Wednesday was a distant memory on Thursday as the reality of the winter season set back in thanks to colder temperatures and a stiff northerly wind pushing wind chill values below freezing. The featured chart presents the minimum wind chill based on hourly reports for each December on record for Des Moines. The minimum so far is just above zero which only has two other years with as warm of a minimum.
Voting: Good - 11 Bad - 0

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Wed Dec 26, 2018
Snow Stays Northwest
26 Dec 2018 05:52 AM
The featured map depicts forecast probabilities of accumulating at least four inches of snowfall over the coming 3 days ending Friday evening from the Weather Prediction Center. The probabilities shown over far northern Iowa are generally below 30% and the highest chances are just to our north and west. Iowa should see a fair amount of rain out of the coming storm system however.
Voting: Good - 10 Bad - 0

Tags:   wpc  
Thu Dec 27, 2018
December SVR Warnings
27 Dec 2018 05:34 AM
While not probable, there is a non zero chance of severe thunderstorms firing over Iowa this afternoon. A powerful storm system will pull warm and moist air into the state and any cloud clearing would allow some marginal instability in the atmosphere to build. Having severe thunderstorm warned storms in the state during December is rare and for the period of 24-31 December, one has to go back to 27 Dec 2008 to find the last warning issued over Iowa. The featured chart presents the number of severe thunderstorm warnings issued over Iowa by month since 1986. The totals for January are even lower than December, so things could be more exceptional than what may happen today.
Voting: Good - 8 Bad - 0

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Fri Dec 28, 2018
Waterloo Tops 1993
28 Dec 2018 05:35 AM
With over 1.50 inches of rain on Thursday, Waterloo Iowa has topped its previous yearly record for precipitation set during the infamous flood year of 1993. The featured chart displays the yearly precipitation totals and 2018 joins just two other years with over 50 inches reported. The rest of the precipitation expected for the site to finish 2018 will come in the form of snow.
Voting: Good - 13 Bad - 0

Tags:   2018  
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Mon Dec 31, 2018
Accumulated Tornado Warnings
31 Dec 2018 05:29 AM
We have arrived to the last day of 2018, so it is a good time to review the year that was. This year was an active for reported tornadoes and the featured chart presents the year to date accumulated number of tornado warnings issued by NWS Des Moines. The main caveat to this chart is that the warning methodology has changed over the years with polygon based warnings now standard. Placing that issue aside, the total for 2018 comes in third highest since 1986. It is interesting to note how far outside of all the other years on record 2004 and 2008 were.
Voting: Good - 11 Bad - 1

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Features for Dec 2018