Top 10 SPC Outlooks by Size
The IEM attempts a robust archive of SPC outlooks. These outlooks have changed methodologies and threshold meanings over the years. You are strongly encouraged to set a start year to limit the data to a given period. The listing only inludes one outlook for a given canonical date.
This app can be slow to generate! For common outlook types, the backend database query can take a number of seconds to complete. The computed area is done within the US National Atlas Equal Area (EPSG:9311).
Related: Top 10 MCDs by Size SPC Outlook Shapefile Download
Top 10 Largest Day: 1 Category: CATEGORICAL Threshold: HIGH
Generated at: 2025-05-01T09:13:47Z in 0.1s
JSON Webservice for the data below:
https://mesonet.agron.iastate.edu/json/spc_bysize.py?day=1&threshold=HIGH&category=CATEGORICAL&syear=1987&sort=desc
| Rank | Canonical Outlook Date | Cycle Hour UTC | Size (sq km) | SPC Link/Image |
|---|---|---|---|---|
| 1 | 1993-06-08 | -1 | 906661.94 | |
| 2 | 1990-06-01 | -1 | 809681.5 | |
| 3 | 1990-03-14 | 6 | 732120.76 |  |
| 4 | 1993-06-07 | -1 | 714248.26 | |
| 5 | 1990-05-15 | 6 | 668685.38 |  |
| 6 | 1988-11-15 | -1 | 667747.31 | |
| 7 | 1989-11-15 | -1 | 662447.38 | |
| 8 | 2004-05-30 | -1 | 624863.3 | |
| 9 | 1994-04-25 | -1 | 614650.97 | |
| 10 | 1991-03-22 | -1 | 614068.73 |
Top 10 Smallest Day: 1 Category: CATEGORICAL Threshold: HIGH
Generated at: 2025-05-01T09:13:47Z in 0.1s
JSON Webservice for the data below:
https://mesonet.agron.iastate.edu/json/spc_bysize.py?day=1&threshold=HIGH&category=CATEGORICAL&syear=1987&sort=asc
| Rank | Canonical Outlook Date | Cycle Hour UTC | Size (sq km) | SPC Link/Image |
|---|---|---|---|---|
| 1 | 2019-05-20 | 1 | 15327.8 |  |
| 2 | 2017-04-02 | 20 | 28323.8 |  |
| 3 | 2010-05-19 | 20 | 30610.9 |  |
| 4 | 2017-04-05 | 20 | 30904.79 |  |
| 5 | 2023-03-31 | 1 | 32131.23 |  |
| 6 | 2010-05-10 | 1 | 32391.16 |  |
| 7 | 2009-04-10 | 16 | 32563.75 |  |
| 8 | 2005-04-11 | 16 | 33562.45 |  |
| 9 | 2008-05-22 | 20 | 33902.43 |  |
| 10 | 2021-03-17 | 1 | 35631.9 |  |