Past IEM Features tagged: freezingrain
Freezing Rain Soundings
03 Jan 2023 05:30 AMYesterday's featured map showed that the Ice Storm Warning is a rather rare headline issued by the National Weather Service. The main reason why it is rare is that a number of factors need to align and the margin between an event turning to all snow or to all rain is very thin. The featured chart presents a quick analysis of Omaha soundings coincident with reports of freezing rain from the airport weather station. There are caveats galore with a plot like this, but some general characteristics are informative. While the Omaha airport was reporting rain at the time, the profile for Monday evening (3 January in UTC) is included as well for a comparison. The left panel shows the air temperature profiles and right panel shows the height of the maximum temperature. In general, the plot shows the classic warm "nose" aloft that allows falling precipitation to melt to rain and then fall into a shallow layer of air near the surface that is just below freezing. The red line shows the profile last night and it can be seen to be too warm to support freezing the precipitation.
Voting:
Good: 11
Bad: 0
Tags: sounding freezingrain
Freezing Rain Reports
04 Apr 2020 04:32 AMA reminder that winter can still happen during April impacted Iowa on Friday with the primary winter mode being freezing rain. Generally warm soil temperatures and the event mostly happening during daylight hours helped to keep the impacts from getting too extreme. One may wonder how common freezing rain events are in April. Well, the featured chart attempts to show this by summarizing airport weather reports from Des Moines. Now there are caveats galore with how freezing rain is reported within automated observations and prior to modernization of the stations, but generally the plot shows only a few events during April with the highest frequency in January. Thankfully, our return of winter was brief with much warmer temperatures expected next week.
Voting:
Good: 10
Bad: 0
Tags: freezingrain
Freezing Rain Profiles
20 Dec 2013 05:39 AMMuch of Iowa experienced freezing rain on Thursday evening and into Friday morning. Freezing rain happens when liquid water, in the form of rain, is able to reach the surface and then freeze as the physical surface and air temperature are both below freezing. In this situation, the layer of below freezing air temperature needs to be shallow otherwise the rain drops will freeze and hit the ground as sleet. The featured chart looks lower atmosphere soundings from the Omaha site during events of freezing rain reported at the Omaha Airport. The cases shown depict the classic freezing rain signature of having a shallow layer of freezing temperature air near the surface with another layer of above freezing temperature air above it. The left hand plot presents the profile of temperature for the 45 cases used in this analysis, including the event from Thursday evening. The right hand plot depicts the level of the warmest temperature for each of those cases. The warm layer of air is centered just a few thousand feet above the ground at temperatures typically above freezing. What would be snow falls into this warm layer, melts and reaches the ground as liquid water. Note: since the case selection was based off of automated data, some of the profiles shown may not have been producing freezing rain.
Voting:
Good: 83
Bad: 16
Abstain: 12
Tags: freezingrain sounding
Freezing Rain and Temperatures
28 Jan 2013 05:48 AMOur most recent storm brought significant freezing rain to Iowa with the largest accumulations over northeastern Iowa. The featured chart looks at the combination of air temperatures with reported road conditions for two locations along Interstate 35. While both locations received freezing rain, conditions improved significantly for Ames as the air temperature rose above freezing. For Mason City, temperatures are still just below freezing and thick fog is not helping the tricky driving conditions this Monday morning.
Voting:
Good: 32
Bad: 6
Tags: freezingrain