Last Build Date: Tue, 24 Jan 2017 13:04:10 -0600
The featured map displays cold season to date snowfall departures based on NWS Daily Climate Reports. Below normal departures are shown in red and above in blue. Much of the Midwestern US has seen below normal snowfall. It will be interesting to check back on this map in a few days after the upcoming snowstorm has passed. The heaviest totals are expected over northern Iowa.
Seeing the sunshine has been a struggle for much of this January. The featured chart considers the metric of having overcast conditions reported by the Des Moines Airport weather station at noon local time. The total for this January is well above average for the month. The forecast does not have much hope for sunshine until this upcoming weekend. On average, this month and December have the highest frequencies.
A Dense Fog Advisory is in effect for the entire state this Friday morning. The featured chart presents some frequency metrics for how often this weather alert is issued for somewhere in the state of Iowa. The top panel shows the weekly frequency of having at least one event for that week per year. The bottom panel shows the overall total number of events. The winter months are certainly the most common time of year for this product with summer having the least. Fog is easier to maintain during the winter thanks to moist air masses over top a colder ground surface which helps to keep air temperatures near water vapor saturation.
Temperatures warmed nicely on Wednesday for much of Iowa. The featured map displays the last calendar date with as warm a high temperature that was experienced on 18 Jan 2017. For locations like Ames and Des Moines, you have to go back to Christmas Day 2016 for as warm a high temperature. For Sioux City, you have to go even further back to 4 December 2016! All the locations with the warmest temperature since Christmas are colored red on the map.
Snowfall totals so far this season have been paltry over southern Iowa. Although we are now half way through meteorological winter, the bulk of our snowfall typically has yet to come. The featured chart displays the before vs after 17 January snowfall totals each winter season for Des Moines. The total this year is about four inches and there have been a handful of previous years around that total as well. The averages for each period are plotted and it shows that the last half of winter is typically the snowiest.
The most significant ice storm to hit Iowa in a number of years is thankfully mostly over. The featured map is an attempted analysis of freezing rain accumulation reports provided by the NWS Local Storm Reports. Please note that areas in northern Iowa are heavily estimated and smoothed due to lack of reports. Hopefully more reports come in on Tuesday and an updated map can be generated. Temperatures are expected to warm this week, which should help to melt most of this recent ice.
A significant winter storm has brought plenty of freezing rain to the state. The featured map displays Monday morning road condition reports with most of the state partially or completely covered with ice. NE Iowa is currently in travel not advised category. Conditions will be dicey today with more rain entering the state and temperatures continuing to hover around freezing. The good news is that the rest of this week looks much warmer, which should help to melt off the ice accumulating now.
A well advertised winter storm is expected to bring significant accumulations of ice to the southern plains and maybe into Iowa. Numerous NWS Offices to our south have issued Ice Storm Warnings in advance of the event. This type of warning is not all that frequent as the conditions for significant icing have to be just right. The featured map displays the number of days since the last issued (prior to the current event) Ice Storm Warning by NWS Office. For many folks under the current warning, it has been a good number of years since a previous warning.
The air temperature difference over the Midwestern US on Wednesday was rather extreme with record highs in Missouri and values below zero over North Dakota. The featured chart displays automated station reports over the region for Wednesday. The bottom panel shows the spread between the coolest and warmest reading by hour. Temperature differences maxed out at over 90 degrees!
Travel was very difficult early Tuesday morning for many Iowans due to a layer of ice that formed on roadways. The setup for this icing event was rather tricky as shown by the featured chart. The chart depicts Jefferson RWIS road pavement and air temperatures, solar radiation observations from the Jefferson KCCI-TV SchoolNet and DOT/DPS Road Condition Reports. The yellow bar represents the time period that a road segment near this road sensor's location was reported to be partially covered with ice. The temperature time series show the interesting combination of having air and dew point temperatures above freezing with road temperatures below freezing. This combination along with falling rain left to the rain freezing on the road surface. The rain also likely helped to wash off much of the pre-treatment done on Monday. The cold front then trucked through after 10 AM dropping the air temperature below freezing as well, but the clouds broke up during the afternoon hours and pavement temps warmed back above freezing even with falling air temps. Many locations further north did not have pavement temps warm back above freezing and icy conditions remain a problem there.
The presence of snow cover has been quite inequitable this winter season. The featured map displays a smoothed estimate of the number of days with at least one inch depth snow cover reported. The gradient depicted over the state is rather large with over 32 days shown near Decorah to only four to eight over most of southwestern Iowa. The presence of snow cover makes a big difference in daily temperatures and soil temperatures. Some of the snow cover will be melted today with above freezing temperatures expected over most of the state.
When it gets cold in Iowa, it seems common to compare our temperatures with a location that is always assumed to be very cold, like Alaska. The large scale weather patterns are such that when it gets very cold in Iowa, it is often not relatively cold in Alaska. The featured chart displays the daily differences in high and low temperature for Ames with Fairbanks, AK. Just a few days during our recent few weeks has Fairbanks been warmer, while most days are significantly colder with an average difference around 35 degrees! So if somebody suggests that you move to Alaska to experience warmer weather, you will want to make the move a very brief one or find a warmer part of the state than Fairbanks.
For the past two days, it has been a struggle to get temperatures out of the single digits and along with a brisk wind, it does not feel pleasant outside. The featured chart displays a time series of air temperature reports from Ames since 1 December of last year. The shaded area represents the range between the climatological daily high and low temperature. Our current cold weather ends a respite since our last cold weather back in mid December. Temperatures are expected to reach 30 degrees by Monday, so something to look forward to!
A fast moving system brought just a dusting of snow for most of southern Iowa overnight. Totals approached an inch near the Missouri border. As an administrative note, the tallied IEM 'Winter Storms' of the season have an arbitrary requirement of two inches of snow or significant impacts. So we won't be counting this as a season storm!
With cold air back in the state for Tuesday and the rest of this week, it is good to provide some optimism for warmer temperatures. The featured chart displays three climatologies for daily temperature for Ames. Two of them are smoothed for the standard climate period of 30 years and the bars represent the simple arithmetic average based on period of record data. It is interesting that while the smoothed climatology show average temperatures rising by the middle of this month, the period of record data continues in the downward direction.
Monday was a rather dreary day with low clouds, freezing rain, and then rain. Winter is the season for such low clouds as shown by the featured chart. The chart depicts a histogram of cloud ceilings as estimated by the Ames Airport weather station. The darker reds represent the more conditions. There is a clear signal in the lowest levels during the coldest half of the year. Low clouds are more difficult to persist during the warmer season as solar inputs generally are able to warm the ground to mix the lower atmosphere.
For the recently finished calendar year of 2016, the Des Moines weather station had the most number of days with low temperature at or above 32 F. The featured chart presents the accumulated total of days for 2016, average, and envelop between the least and greatest accumulation. The 2016 total of 275 days eclipses the previously largest total set just last year of 273 days.
Just in time for the New Year and to qualify for the 2016 tax benefit, more help has been added to the IEM workforce. Little Charlotte was born on the 28th and is spending a little extra time in NICU before starting work hopefully early next week. The family is doing well and I'll catch up on the backlog of emails soon, thanks for your patience!
The weather has certainly been active for the recent few days. The featured Gaant Chart depicts watch, warning, and advisories issued by the Omaha NWS Office for the past four days. A little bit of everything can be found with severe thunderstorm warnings book-ended by winter weather, fog, and wind advisories. It is a fun aspect of living in the Midwestern US, the weather is rarely boring!
The weather was quite atypical of what one would expect for Christmas. A round of storms with occasional thunder lifted north over the state during the morning. A cold front with more rain moved west to east over Iowa during the evening. Warm air surged into the state ahead of the front with some locations over 50 degrees. For Sioux Falls Airport, over an inch of precipitation was reported, which easily made for a record for the date. The featured chart displays daily Christmas precipitation for the site. The record setting precipitation was double the previous record set in 2009.