This March finished without a severe thunderstorm nor tornado warning issued by the National Weather Service for Iowa. While March is typically an active month for severe weather in Iowa, there have been other years since 1986 like this March as shown by the featured chart. The bottom panel compares the March total number of warnings with the full year total. There is not much correlation between March and the rest of the year. We have yet to have an April without severe weather warnings since 1986. The first week of April looks to be mostly quiet with temperatures struggling today in the 30s!

March 2012 was one of the relatively warmest months on record for Iowa. Our most recent March of 2013 was not a repeat performance. The featured chart displays the daily high and low temperature for March 2012 and 2013 along with the daily climatology for Ames. Places that the bars overlap are the purple color. Only March 4th of this year had a warmer high temperature than for 2012. For some days, there is a 30 degree difference from the low temperature in 2012 to the high temperature this year!

The featured chart compares the average temperature this year over a given number of days prior to and including April 2 for Ames with the same period for previous years. The bars indicate the most recent year with as cold or colder temperature than this year. For example, the past 10 days this year are the coldest since the same period during 2001. The forecast continues the warming trend we have been on with 60s expected later this week!

Our lack of really warm days and snows in March have not helped soil temperatures much as shown by the featured chart. The exact opposite was true in 2012 and the response was to have some of the warmest soil temperatures recorded since 1988 by mid March. Eventually, climatology will win this battle and soil temperatures will warm enough to permit gardens to be planted and agricultural crops to go in. Warmer temperatures for the rest of this week will help as well.

As featured a few times in recent months, it was very unlikely that the drought conditions in the state would be busted over the winter season. There just is not enough precipitation possible to make up long term deficits during the cold season months. We were fortunately for a number of heavy snowfall events that have put a small dent into the drought situation and even eliminated it for parts of the state. April has started off dry, but that looks to change with rain chances arriving this weekend and lingering into next week.

The NAM forecast model runs four times per day with each run producing a forecast out a number of days. The featured chart presents the summation of the 96 hour precipitation forecast for a model grid cell near Ames and then the departure from what was reported by the airport weather sensor. For most of the winter season, the model has overestimated precipitation. The current forecast has Ames getting nearly an inch over the next few days.

Wow! Monday was the long awaited taste of Spring with highs in the 60s and 70s along with sunshine. For many sites in Iowa, it has been a long while since temperatures were this warm. The featured map shows the high temperature on Monday and the number of days since as warm a high temperature. Places like Des Moines had the warmest temperature since mid November. Some other locations were the warmest since late October 2012. This taste of Spring was brief as colder weather arrives today along with chances of snow!

There was no shortage of interesting weather on Tuesday as shown by the featured map. At 6 PM, a severe thunderstorm watch, an ice storm warning, a severe thunderstorm warning, and a flood watch were all active at the same time in Iowa! In fact, one of the severe thunderstorm warnings was overlapping a winter weather warning. The map also shows the reported air temperature at that time. The severe thunderstorm warning over NW Iowa was with an air temperature near freezing while SE Iowa was near 80 degrees! Over the Midwest, a lot of hail fell over areas near freezing. The instability to support the thunderstorms was above a layer of very cold air near the ground. The active weather continues today with just about everything imaginable happening at once.

Having hail from spring time thunderstorms is not an exceptional event. Having hail while near surface air temperatures are near freezing is exceptional. The featured chart compares recently reported hail size and an approximate surface air temperature from a nearby reporting station. It is remarkable to see so many hail reports at temperatures even below freezing. The thunderstorms were feeding off of instability based well above the surface. Having a cold layer of air near the surface also helped hail stones to reach the ground without mostly melting on the way down.

While we are in the second week of April and Spring started a number of weeks ago, our actual weather has been a different story. Northwest Iowa picked up the heaviest snowfall totals in the state from our recent storm. Totals were much higher to our north and west along with significant amounts of freezing rain causing major problems. Is this our last snow maker of the season? Some numerical models bring us more snow next week!

Our recent stretch of rain, hail, freezing rain, sleet, and snow has been a big help for the drought situation in the state. The featured chart shows the IEM estimated seven day statewide precipitation total since 1 Jan 2011. Our recent total just over two inches has been difficult to come by since mid 2011. More precipitation is in the forecast with chances just about every day for the next week.

Our recent stretch of wet weather has helped to put a dent in the drought situation in the state, but the long term deficits remain rather large. The featured chart shows the 30, 60, and 365 day running precipitation departures. The 365 day line shows a curious downward movement even while it has recently rained!? The reason is that the rainfall we got on Sunday was an half inch less than what we got on the same day during 2012. It is going to take much more rain to catch up the long term deficit, but we are about to enter a conflicting period of wishing for rain and at the same time wishing for dry weather so that crops can be planted.

Yesterday's feature showed the 30, 90, and 365 trailing departures of precipitation for Iowa. Today's feature shows every daily departure to-date since 1 Jan 2011. The Iowa areal average is shown along with data for Ames and Sioux City. Our above average period currently takes us back to around the first of September before the deficits quickly add up. Over which period is the total deficit the most important? It depends on the application. For example, your lawn may only care about a couple week deficit as its roots are shallow and it lives on day to day rains. Trees have much deeper roots and are more sensitive to longer term droughts as the soil water is depreciated. There is still hope for more rain this week with thunderstorms likely and then another chance of snow!

Our weather has been on the cold side of average for much of the past two months. The featured chart shows the accumulated net number of days with a high temperature above average for Ames. The comparison between 2013 and 2012 ends around 17 February as about every day after that was above average in 2012 and most have been below this year. For this metric, 2012 was the most extreme year for net number of days above while 1979 had the most below. 1947 has the closest fit to this year and is shown as well. The cold weather looks to continue into next week.

Rainfall was plentiful over much of the state on Wednesday as shown by the featured map of NOAA NMQ precipitation estimates. These estimates are primarily based off of RADAR information and show a large swath of the state in the 3-6 inch total range for Wednesday. So we are rapidly transitioning from a drought condition to flooding now with more precipitation on the way along with snow for northern Iowa. Based on some preliminary IEM estimates, yesterday's statewide averaged precipitation was 1.93 inches, which would be the highest calendar day total since 13 September 1961!

Our most recent storm was one for the record books as it appears it will rank in the top 5 for statewide heaviest rainfall. The featured map displays the reported daily precipitation for the ASOS/AWOS sites on Wednesday along with the period since the last event of as large amount. The heaviest swath fell from the Lamoni to Dubuque area with Ottumwa reporting nearly 5 inches, which makes for its largest one day total in 20 years! Monticello came in with just over three inches and its largest total in just under 10 years.

The snow storms in April for Iowa continued this week with our most recent bout of winter bringing over 6 inches of snow over extreme northwestern Iowa. This storm system also brought one of the heaviest widespread rainfalls in Iowa history for the rest of the state. Is this finally our last snowfall or could more be on the way? Unfortunately, more cold weather and snow looks possible next week!

The featured chart presents an IEM computation of the maximum two calendar day precipitation total for Iowa. The two day total from last week's storm came in at just over 2.5 inches, ranking it third all-time behind 1961 and 1946. While this event has produced flooding, it has also put a huge dent into the drought situation in the state. More rain and even some snow for northwestern Iowa is in the forecast for today.

With snow once again visiting the state, our recent stretch of weather has certainly been on the wet and cold side of average. How did we get to this point? The featured chart is sometimes called a phase plot and is often used to explain business cycles. Is this context, the line traces a time-series of 14 day temperature and precipitation departures since November 2012. There is a nice property of these plots as they tend to make loops as physical processes in our atmosphere interact on timescales longer than one day (think passing series of storm systems and air mass regime changes). By normalizing the axes to standard deviation departures from average, the time-series is constrained and will nicely oscillate around within the plot as temperature and precipitation departures somewhat correlated. Anyway, you can see the large jump we have recently taken to over 4.0 SD on precipitation and -1.5 SD on temperature! From here, we have to loop back to somewhere at least drier (we are currently at a precipitation extreme) and hopefully warmer. Thankfully, the forecast is hinting at just that with warmer weather for this weekend and less rain.

The remarkable April weather continued on Tuesday with our most recent storm system bringing the heaviest snowfall to northwestern Iowa and even producing a brief dusting over parts of southern Iowa. Is this finally the last storm of the season that brings along snow for Iowa? The forecast does hold some hope that it is. These late April snow storms are somewhat rare for Iowa, but do occur roughly once every eight years or so.

April has been on the wet side of average for much of Iowa. For a few days last week, Waterloo had its highest year to date total on record as shown by the featured chart. The top panel presents the year to date precipitation total rank and the bottom panel is the departure from the previous maximum total. The forecast continues to look mostly dry with much warmer temperatures, just what farmers currently need to get the crops planted.

The heavy rains of April have improved the drought situation in the state considerably, but the featured chart shows that Iowa is still slightly worse off than last year at this time and in the worst condition since 2003! The precipitation deficit accumulated from last year will not be made up for in a month, but will take more wet months to come. The immediate term forecast looks warm and dry, which will help the crop planting progress in the state.

Warm air finally arrived for much of the Midwest this past weekend. The featured map displays an analysis of the difference between the high temperature on Friday to the warmest temperature reported up until that date this year. Much of Wisconsin, Minnesota, and North Dakota is shown in the 15-30 degree range. This represents a rather remarkable "jump into spring". Unfortunately, much colder air is forecasted to arrive midweek and highs this coming Friday only in the 40s!

The calendar is about to turn into May, but nearly all of the state's agricultural ground has yet to be planted. The wet and cold April has created two problems for farmers. Fields are too wet to transverse with equipment and the soil is too cold to support growth. The featured chart presents the weekly USDA corn crop planting progress report. Only a few years since 1979 have been as slow as this year. Our recent few days of warm and mostly dry weather has allowed some to get started, but the weather is about to turn very cold and wet for early May.