Last Build Date: Fri, 30 Sep 2016 16:47:42 -0500
The Des Moines Airport has yet to reach a sub freezing temperature, let alone a sub 50 degree temperature! If this holds for a few more days (thru 1 October), it would break the previous record for latest sub 50 degree temp set back in 1905. The featured chart displays the combination of first day below 50 and then the subsequent number of days until the first sub 32 temperature was recorded. The slanted lines are simply a convenience to bring the second date down to the timeline axis.
So far this fall, we have avoided any really cold weather. The featured chart displays the minimum to date low temperature for Des Moines after 1 July. The coldest low temperature thus far has only been 50 degrees. This value is one of the warmest to date minimum temperatures on record for the site. The featured chart displays the accumulated value for this year and the long term climatology of this value.
The featured chart displays the daily average wind speed and direction for Des Moines this month. The cooler and less humid conditions this week have been thanks to winds which are no longer coming from the south as they were last week. The arrows on the top of the chart display the vector averaged wind direction each day. Prior to this week, the periods without southerly winds were rather limited.
The big story in the state is the ongoing flooding of the Cedar River in Cedar Rapids. This flooding water is from rainfall last week over northeastern Iowa. The featured chart displays sequential river stage forecasts for the CIDI4 (Cedar River at Cedar Rapids) site. Forecasts are made out a number of days and updated a few times per day during active flow situations. The plot presents each of these forecasts and the observed data for the site. Thankfully the forecasted crests have slowly crept lower with time as the event has gotten closer to town.
The weather feels much more like fall now after a very muggy and summer-like previous week in September. The featured chart presents the number of days each September that the maximum hourly dew point was at or above 70 degrees. This year's total is similarly anomalous to last year's total with the long term average near 3 days. The year of 1978 comes up as the winner in this chart with thirteen days shown.
The featured map displays MRMS precipitation estimates from noon Tuesday thru noon Thursday for NE Iowa, SW Wisconsin, and SE Minnesota. Amazingly, three different areas are estimated to have received over 10 inches during this period. The heaviest rainfall in Iowa fell near Greene with an actual report of over 10 inches to match the estimates. Sadly, more rain fell in the area overnight and more chances of rainfall are in the forecast for this weekend.
The extremely muggy weather for September continues with Des Moines experiencing almost 1.5 straight days with a dew point temperature at or above 70 degrees. The featured chart displays such streaks in September for the site. The current streak ended this morning at 3 AM, but it sure shows up as an outlier compared with similiar streaks happening much earlier in the month. The plot even shows a slightly longer streak happening earlier this month on 6-7 September.
The muggy weather this September continued on Tuesday with dew point temperatures reaching 70 degrees for much of the state. The featured chart presents some metrics on the number of hours each September with an average dew point at or above 70 degrees. The total for 2016 is already the third largest since 1973 according to the top panel. The bottom panel shows the average number of days each September with such a dew point temperature at the given hour. Again, 2016 totals are way above average. There is concern that the muggy weather is going to lead to mold development in the already mature agricultural crops. Once mature, a hard freeze followed by warm and dry conditions are best to help dry out the crop for harvest. So far, we have experienced neither of these this September.
A Tornado Watch was issued yesterday for portions of eastern Iowa. Thankfully the tornado threat never materialized and the severe storms were isolated. How often do we see a tornado watch issued in September or later? The featured chart displays the period between the first and last tornado watch issued by NWS Des Moines each year. The anomalous drought year of 2012 skews the numbers a bit, but a majority of years plotted have had watches this late in the season, We are in an active pattern this week, so more severe weather is possible.
The featured chart displays daily solar radiation for the past eight days from the ISU Ag Farm station. The black line represents a clear sky theoretical maximum value for the day. You can see that this line is sloping downwards as the ever shortening day and lowering soil angle yield lower energy totals each day. We did see plenty of sunshine for the past weekend and the two values shown are close to the clear sky computed maximum. This week looks to be a mixture of sunshine and storms with mild temperatures.
Dew point temperatures approached 70 degrees over much of the state on Thursday, helping to fuel heavy rainfall producing storms. Muggy conditions have been the norm for most of this warm season as shown by the featured chart presenting daily mixing ratio values and departures for this year. The bottom panel shows the departure from average with blue bars representing more humid than normal. The humid conditions have stuck around since mid June.
CoCoRaHS is a citizen science project that supports the collection of daily rainfall reports. Using a standardized rain gauge, folks can report their precipitation totals to a website. There are number of CoCoRaHS observers in the state, but we have yet to reach having at least one active observer in each county in the state. The featured map displays the number of active users per county, whereby activity is just having one precipitation report made in the past year.
Temperatures struggled on Tuesday to warm in the state. Estherville was even unable to reach 65 degrees for a high temperature. The featured chart displays the frequency of sub 65 degree high temperatures for September for the site. Having such cool temperatures are certainly not out of the ordinary and the site roughly sees 6 days per year per September below this level.
Relative Humidity is one of the more commonly expressed weather variables. It represents the percentage capacity that the air is full of water vapor. Since the value is relative, it is difficult to directly compare the value at different air temperatures. While the air certainly feels drier in the winter time, the relative humidity values are just as high as the summer time. The featured chart presents a computed climatology of RH for Ames. The blue bars represent the daily range of RH values for each day this year. The blue, green, and black lines are simple averages of the daily min, avg, and max. The red line represents the frequency of days with the maximum RH at or above 95%. A lot going on with the chart! Of note for this time of year is that relative humidities are dropping. Demand for water and subsequent transpiration by agricultural crops is on the rapid decline. You may have noticed the corn and soybeans are turning brown now! These lower RH values help to dry out the fields and crops to allow for harvest.
The weather this past weekend certainly felt like fall with very cool temperatures and plenty of sunshine. The featured map displays morning lows on Sunday with values below 50 degrees highlighted. The wonderful temperatures look to continue this week along with some chances of rain.
Since the beginning of the project, the IEM has archived a number of datasets and products to support research efforts. This archive is made immediately available within a browsable directory tree. The featured chart displays a report of the amount of data archived each day and the accumulated size of the file based storage. A number of data points are labelled when archiving changes created an uptick in volume size. Although the cost of storing data continues to decrease, the size of various products that would be nice to archive continues to increase.
The featured chart displays the combination of hourly temperature reports from the Ames Airport and daily high and low climatology. Our recent weather has seen a warming trend while the daily climatology is on the downward glide into fall. The very warm weather appears to be behind us now with forecasted temperatures for the next seven days in the 70s and 50s.
Flash Flood Watches were issued yesterday for expected heavy rainfall overnight and into today. These watches are issued by NWS Weather Forecast Offices (WFOs) and the featured map displays the number of days since the last such watch issued by a WFO in the country. For some parts of the country, it has been over a year since the last such watch was issued. The current watches over the desert southwest are related to moisture from Hurricane Newton.
The featured map displays Weather Prediction Center forecasted precipitation totals for the next seven days. Much of Iowa is shown in the 2-3.5 inch range with higher totals to the south in Missouri. It is late in the growing season for rain to do much good for the agricultural crops in the state. The primary impact of any rain received now would likely be to delay the fall harvest progress.
After a very pleasant and cool start to the Labor Day weekend, Monday will be much warmer with highs well into the 80s. The featured chart presents the Labor Day high temperatures each year for Des Moines. The overall average comes in at 81 degrees, so we'll be above that this year. A caveat to plots like these is that long term daily temperature records are often observed in the morning, so the reported 24 hour high temperature was likely for the previous day.