Past IEM Features tagged: swaw

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One Hour Flash Flood Guidance

30 Mar 2018 05:33 AM
Today wraps up Severe Weather Awareness Week in Iowa and today's topic is flooding. Flooding is one of the top weather related cause of fatalities in the United States. Flooding can happen quickly as a result of heavy rainfall and the featured map is a diagnostic on how much rainfall is needed over an hour to result in non-urban area flash flooding. This product is generated by the National Weather Service River Forecast Center and you can generate maps like these on the website for current and archived dates.

Voting:
Good: 13
Bad: 20
Abstain: 1

Tags:   swaw   ffg  

Severe TStorm Warnings by Time of Day

29 Mar 2018 05:34 AM
This is Severe Weather Awareness Week in Iowa and Thursday's topic is family preparedness. Severe Thunderstorms are possible at any time of the day and at times when your family may not be home together. The point is to think about how your family receives warnings when not all together, takes action on those warnings, and advises each other of their status during and after the event. Along these lines, the featured chart presents the time of day frequency of Severe Thunderstorm Warnings issued by NWS Des Moines. While certainly there is a peak in frequency around 6-7 PM, the rest of the day are non-zero values meaning severe storms are possible during all hours of the day. Thankfully individual storm systems provide more narrowed threats in time and the vast majority of days in Iowa are severe storm free. These events are rare enough that it is important to raise awareness and review your action plans in early spring each year.

Voting:
Good: 11
Bad: 1

Tags:   swaw   nws   warnings  

Tornado Warning Polygons

28 Mar 2018 05:33 AM
This is Severe Weather Awareness Week in Iowa and Wednesday's topic is tornadoes. Tornadoes have been recorded in Iowa during each month of the year and about every hour of the day. The NWS issues Tornado Warning "Storm Based Warnings" in the form of geographic polygons. While the featured map may look like your grandmother's quilt, it is actually a map showing the last year a location in the state was under a Tornado Warning. The archive for these polygons goes back to 2002, but they were not the operational warning until late 2007. There are a number of interesting artifacts on the map including some slivers of the state that have not seen a polygon Tornado Warning since at least 2002. You can generate maps like these on this website for other states along with many other options too!

Voting:
Good: 15
Bad: 1

Tags:   swaw   nws   tornado  


NWS Warning Reception

27 Mar 2018 11:06 AM
This is Severe Weather Awareness Week in Iowa and Tuesday's topic is warning reception. There are many ways to receive alerts when the NWS issues a warning for your location. Relying on hearing a siren before taking action is problematic as sirens are meant to alert folks while outdoors and are single points of failure. Sirens also are not used to alert people to threats like flash floods. The NWS has provided a few links for your review

The IEM provides a number of non-operational / educational ways to receive NWS Warnings. These include services provided by "IEMBot" such as RSS feeeds, Twitter automated posts, and real-time web apps.

Voting:
Good: 4
Bad: 0

Tags:   swaw   nws  



Severe Thunderstorm Threats

26 Mar 2018 08:57 PM
This week is Severe Weather Awareness Week with Monday focusing on severe thunderstorms. The National Weather Service issues a Severe Thunderstorm Warning when it expects damaging winds over 58+ MPH and/or hail larger than one inch diameter. When the NWS issues their warning, it includes coded "tags" indicating their estimated wind speed and/or hail size. The featured chart looks at the frequency of these tags within the warnings. The most common thunderstorm warning (over one in three) is for 60 MPH winds and one inch hail. Thankfully the frequencies drop off considerable has you move to more intense thresholds. Iowa has yet to see a Severe Thunderstorm Warning yet this year. The peak for these warnings comes in late June.

Voting:
Good: 11
Bad: 0

Tags:   swaw   ibw   nws