Iowa Environmental Mesonet Daily Bulletin for 21 April 2024


No news is good news

IEM Code Pushes <to branch> on Github

Daily Feature

Eclipse Solar Radiation
Date: 20 Apr 08:03 AM
Votes: Good: 8   Bad: 0 Abstain: 0

For the 8 April eclipse, the ISU Soil Moisture Network put its southeastern most station (near West Point, IA) into a rapid scan mode to observe atmospheric variables at a 15 second interval. This station subsequently suffered a communications outage and did not come back online until yesterday! So with this data in hand now, a daily featured chart should at least be made. The chart focuses in on the eclipse period and attempts to address the question if the percentage of the sun covered by the moon is linear to the decrease in received solar radiation. The black line shows the 15 second observations, the red lines denote the period of the eclipse, the green line is an estimate of received radiation if the sky was clear and there was not an eclipse, the blue line is the eclipse coverage percentage, and the black dashed line represents the linear model. So while the relationship looks good and intuitive, it is not exact as the impact of received radiation is very nuanced with lots of small effects causing small variances in this linear model. If you want details on the minutia involved, ask Google Scholar.

NWS Watch/Warning Summary for 12 AM 20 Apr 2024 - 12 AM 21 Apr 2024 CDT

Summary By WFO Watches
Tornado 0 0 0 0 0 0 0 0
Svr Tstorm 56 0 0 0 0 0 0 1
Flash Flood 2 0 0 0 0 0 0---

ARX = LaCrosse, WI DVN = Davenport, IA DMX = Des Moines, IA OAX = Omaha, NE FSD = Sioux Falls, SD

IEM Cow Report

SVR+TOR Warnings Issued:  55 Verified:  20 [36.4%]
Polygon Size Versus County Size            [24.4%]
Average Perimeter Ratio                    [22.4%]
Percentage of Warned Area Verified (15km)  [21.1%]
Average Storm Based Warning Size           [1253 sq km]
Probability of Detection(higher is better) [0.96]
False Alarm Ratio (lower is better)        [0.64]
Critical Success Index (higher is better)  [0.36]