The featured map displays IEM computed unofficial precipitation total ranks for April by climate district. For Iowa, April was a bit on the dry side with the driest portion of the state being the southeastern corner. For the Midwest, the contrast was between the far southeastern and northwestern portion. Our stretch of dry weather that we ended April with looks to come to an end with numerous chances of showers and thunderstorms in the coming week.

Heavy rainfall and severe weather have been noticeably absent from Iowa so far this spring. One reason for that has been the lack of really moist air that help to drive both aforementioned phenomena. The featured chart displays the daily maximum dew point temperatures reported by the Ames Airport weather station. The 60 degree level was finally reached on Sunday for the first time this year.

The featured map displays NOAA MRMS "Q3" precipitation estimates for Monday. The map shows a lot of variability over the state and even within counties with the amount of rainfall received. The typical thunderstorm is smaller in horizontal size than an Iowa county, so their exact track can lead to large differences in precipitation over a single county. The hope is that over long enough time periods, these individual thunderstorms start to even out totals over a county but that is not always the case.

The USDA updated corn planting progress valid for 3 May shows that Iowa farmers had a very productive last week with 54% of the projected corn acres getting planted over the past seven days. The featured chart displays the percentage of acres planted over the seven day analysis periods for each year since 1979. The highest weekly total is shown on the left hand side of the chart. This analysis would indicate that it is common for such a high percentage of acres to get planted within one week. Progress this week has slowed considerably with numerous rounds of rain.

The featured chart displays the daily climatology of growing degree days for Ames along with the actual values (dots) for this year. We have seen plenty of above average days this spring with each day so far this May above average. Our average daily accumulations this time of year are half of what we can expect during the warmest time of the year. Having warm over night low temperatures makes a big difference with the computation of this value.

The weather does not get much more active than what the US will experience this weekend. The featured image presents the Friday morning issued outlooks for Friday, Saturday, and Sunday by the Storm Prediction Center. The highest chances of severe weather for Iowa will be on Sunday. Meanwhile, heavy snowfall is expected over the eastern Rockies and there is a sub-tropical storm named Ana off the southeastern US coast. Something for everybody this weekend!

The featured chart looks at the distribution and contribution of daily precipitation to the year to date total of days with precipitation and total precipitation. The daily values are binned into groups that, on average, provide equal yearly totals of precipitation. For Ames, while the heaviest bin has yet to see an event, the second highest bin has seen double of the average number of events.

Monday was a chilly and windy departure from the near summer like weather we have recently been experiencing in May. The high and low temperature were both the coldest so far this month for many sites in the state. The featured chart looks at the frequency of a given May day being the coldest for the month. Having the 11th be the coldest day is not out of the ordinary and the chart would indicate that perhaps our coldest weather of the month is now behind us!

The featured chart presents a time series of air temperature for the Des Moines Airport since the first of April. Our recent few days of chilly weather was some of the limited time we have spent with a temperature below the daily average low temperature as depicted by the blue bars. The forecast has rain returning today with thunderstorm chances for the weekend.

The IEM generates a nationwide composite of NWS RADAR information going back to 1995. The featured image presents that composite for Iowa for each 7 AM on 14 May going back to 1995. The widespread rain this morning is only matched in RADAR presentation by the same time in 1996. You can generate this image online and for an area/time of your choice.

The featured map displays the number of hourly observations on Thursday that contained measurable precipitation reports. For many locations in the state, the rain lasted for much of the day yesterday. More rain is in the forecast for this weekend along with chances for severe weather.

Early Sunday morning, the Des Moines NWS Office issued a few tornado warnings during the 3 and 4 AM hour. The featured chart looks at the frequency of issuing tornado warnings by the office by hour of the day. As one may suspect, tornado warnings are rather rare at that hour, but the overall minimum is a bit later in the morning. The vast majority of warnings are issued in the late afternoon and evening hours as strong thunderstorms need the heating of the sun to drive instability in the atmosphere. You can generate this plot online and you may wish to compare this plot with one from a gulf coast forecast office, like Mobile.

While there have been numerous rounds of rain this May in the state, the events have not been too widespread which has allowed corn planting progress to proceed at a good clip. The featured map shows updated estimates from the USDA of percentage of corn acres planted in the state. Only Kansas is shown behind long term average as they have had many significant rain events this spring.

Really warm weather has been difficult to come by so far this spring season. The featured map displays the year to date maximum temperature percentiles. A percentile of 100 would mean the maximum temperature this year for the station was warmer than any other year since 1951. Most of the values in the state are well below 50, which is an indication of cool temperatures. Today will be another very cold day, but warmer weather returns tomorrow with highs only in the 70s though.

For Ames, the high temperature on Wednesday was only able to reach 50 degrees. The featured chart shows the daily high and low temperatures so far this month along with the daily climatology. Having a high temperature of 50 on 20 May is even cooler than the average low temperature for the date!

The featured map shows locations that have recently reported temperatures below 36, 32, and 29 degrees this week from the Iowa COOP Network. The coldest temperatures avoided Iowa, but some low laying areas in the state likely saw a bit of frost this week. This weekend is the unofficial start of summer, so hopefully these near freezing temperatures are not returning until later this fall. The near term forecast has a return to more typical temperatures for this time of year along with chances of rain.

The big weather story in the US is the ongoing historic flooding in Texas and Oklahoma. A number of locations in the area have sent monthly precipitation records and there is more rain in the forecast today. The featured chart looks at the number of flash flood warnings issued by the Norman (Oklahoma City), Oklahoma NWS Office. This year's total dwafts other years for the year to date period. For the entire year, this year is only behind 1995 and 1999.

While not a complete washout, there were showers and thunderstorms this past Memorial Day weekend. The featured map displays four day total estimates from NCEP. Most of the eastern half of Iowa is analyzed to have received over an inch with lower totals in the west. Stronger thunderstorms on Monday evening dropped isolated higher totals over northern Iowa. More rainfall is in the forecast later this week.

Very warm temperatures have been difficult to come by so far this season. Places like Des Moines have yet to see a 90 degree temperature. The featured chart looks at the date of first 90+ degree temperature of the year and the number of days that year at or above 90. The red line shows the cumulative frequency of first date and the mid point of the line (average first date) is still a week away, so not hitting 90 yet is not abnormal.

The unofficial period of summer is considered to be the days between Memorial Day and Labor Day. If you consider summer to be the 91 (quarter of the year) warmest day period of the year then the featured chart shows you when this period started for each of the past years for Ames. This analysis would indicate that we have, on average, just over a week left of spring before summer starts. The near term forecast would indicate that as well with pleasant temperatures for the next week.

While overall precipitation totals this month have not been too impressive, the number of hours on which it has rained has been much above long term average as shown by the featured chart. The chart shows the number of precipitation hours this year and a long term monthly average based on available archive of observations. You can generate this chart on the website for a year and observation site of your choice.