3 Chapter 3 — Current Conditions: What’s Happening Right Now
The IEM is primarily known for its historical archive and analytical tools, but it has a capable real-time layer that most users never fully explore. The current conditions section is not one page — it is a collection of distinct tools scattered across several URLs, each serving a different purpose. Some are in the navigation menu. A few are not. This chapter covers all of them and explains when to reach for each one.
The Current Mainpage
The entry point is mesonet.agron.iastate.edu/current/, which functions as a menu of real-time map products rather than a display in itself. From here you select a variable — Air Temperature, Humidity, Precipitation, Pressure, Snow, Soil Temperature, Station Plot, Sounding, Wind, or Visibility — and the IEM generates a map product for that variable across its observation network.
These maps are static images that refresh on a schedule, not interactive layers. They are generated from the combined IEM network, blending ASOS, COOP, RWIS, and other stations into a single visualization. The station plot option produces the classic surface analysis plot format — the circular station model with temperature, dew point, wind barb, sky coverage, and pressure all encoded around a central point — which is the most information-dense view available and the one most familiar to anyone who has spent time looking at surface analyses.
The precipitation map at /current/index.phtml/precipitation is worth bookmarking specifically during active weather events. It aggregates current precipitation reports from across the network and gives you a quick ground-truth check against whatever the radar is showing.
Sortable Currents: The Cross-Network Observation Table
The most useful real-time tool on the IEM for a weather enthusiast is Sortable Currents, reached from the navigation menu at mesonet.agron.iastate.edu/my/current.phtml. Despite the “My Favorites” label in the URL, this page is far more than a favorites list — it is a full cross-network observation hub that lets you view current conditions from every network the IEM tracks in a single sortable table.
The page opens with a set of network tabs at the top: ASOS, CoCoRaHS, COOP, Cellular COOP, DCP, ISU Soil Moisture, Other, SCAN, My Favorites, By State, RWIS, RWIS Surface, RWIS Traffic, RWIS Soil, By NWS WFO, and USCRN. Each tab loads the current observations for that network in a table where every column header is clickable for sorting. Click the temperature header and every station in the network sorts from hottest to coldest. Click precipitation and you instantly see which stations are reporting the most rain right now. Click dew point and you can immediately identify where the moist boundary sits.
The “By State” tab is particularly useful for regional situational awareness. It lets you select a state and see all ASOS observations across that state simultaneously — a faster and more flexible view than the map products when you want to compare readings across a region rather than look at one variable spatially.
The “My Favorites” functionality requires no login. Visit any network’s current conditions page, find a station you want to track, and add it to your favorites with a single click. The favorites list is stored in your browser’s local storage, so it persists across sessions without requiring an account. A custom favorites list combining your regional ASOS stations, a nearby CoCoRaHS observer, and a RWIS pavement sensor gives you a tailored real-time dashboard that no commercial weather site can replicate with this combination of networks.
The “By NWS WFO” tab at mesonet.agron.iastate.edu/nws/obs.php deserves separate mention. It lets you select a Weather Forecast Office and see all current ASOS observations within that WFO’s area of responsibility in a single table. For mid-Atlantic users, selecting CTP (State College) pulls up every airport station from central Pennsylvania — MDT, CXY, LNS, THV, SCE, IPT, RDG and more — in one sortable view. This is exactly what you want when a front is moving through and you are watching temperatures fall or dew points rise from west to east across a region.
IEM One: Radar and Warnings in a Single Interface
mesonet.agron.iastate.edu/one/ is a modern interactive mapping application that combines radar imagery with live NWS warnings in a single interface. It is one of the most polished tools on the IEM and, for real-time severe weather monitoring, the best starting point the site offers.
IEM One has two modes: Real-time and Archive. In Real-time mode it displays the current NEXRAD composite radar loop alongside any active watches, warnings, and advisories overlaid as color-coded polygons. The warning panel on the right side lists every active warning by WFO with the phenomena, significance, and expiration time. Click any polygon on the map and you get the full warning details.
Archive mode is where IEM One becomes genuinely powerful for post-event analysis. You can navigate to any date and time and replay the radar and warning sequence exactly as it unfolded. The time navigation controls at the bottom let you step through the archive at whatever pace you want. This is the tool to use when you want to understand the timing of a warning relative to the radar evolution during a past event — something that takes considerable effort to reconstruct from text archives alone.
The layer controls, accessible via the hamburger menu in the top left, give you options that go beyond basic radar and warnings. You can toggle on webcam imagery from the IEM camera network, Iowa DOT truck dashcams (available back to 2014), Iowa DOT RWIS road cameras (back to 2010), and RWIS surface observations with a choice of which variable to label on the map — air temperature, or any of the four pavement temperature sensors. Overlaying RWIS pavement temperatures on a radar loop during a winter precipitation event is a combination that no commercial weather site offers and that is genuinely useful for understanding where ice is forming on road surfaces in real time.
IEM One also supports URL parameters for deep linking into specific views. If you want to share a specific location and zoom level, you can construct a URL with zoom=, lat=, and lon= parameters. You can also pre-configure which layers are visible: radar=1, warnings=1, rwis=1, webcam=1, dashcam=1, sps=1. This makes it easy to set up a bookmark that opens directly to your region with your preferred layer configuration.
The Severe Weather Mainpage
The Severe Weather Mainpage at mesonet.agron.iastate.edu/current/severe.phtml is less a real-time monitoring tool and more a hub connecting the IEM’s severe weather resources — both current and archived. It is worth understanding what is on it because some of the most useful links on the entire site are buried here rather than in the main navigation.
For current conditions, the page provides a link to the iembot monitor for watching text products arrive in real time, the current NEXRAD storm attributes shapefile (a point shapefile updated every minute with hail estimates, rotation, and storm top heights for every tracked cell in the country), a convective watches overview showing the last ten SPC watch locations, and GIS-ready downloads of the current 24-hour LSR reports and active warning polygons.
For operational situational awareness, the current SPC and WPC outlooks are displayed side-by-side with IEM’s own rendering of the same data pulled from its archive — a simple visual check that the IEM’s ingest is working and matching the official products. On a day with active outlooks this is a useful confirmation that the IEM’s warning and outlook archive is current.
The archived tools linked from this page — IEM Cow, IEM Raccoon, the VTEC browser, the warning search — are covered in depth in Chapter 7. What is worth noting here is that this is where you find them when approaching from the “current severe weather” angle rather than from the NWS Data menu.
The Precipitation Current Page
For active precipitation events, mesonet.agron.iastate.edu/current/index.phtml/precipitation gives you the combined network precipitation map — all reporting stations from ASOS, COOP, and CoCoRaHS plotted simultaneously. This is the IEM’s equivalent of a real-time gauge analysis map. It updates as new reports come in and gives you an immediate sense of where precipitation is heaviest and how gauge reports compare to what the radar is showing.
For more detailed precipitation tracking, the Hourly Precip application at mesonet.agron.iastate.edu/rainfall/obhour.phtml shows the precipitation reported by each ASOS station in the last hour alongside a running 24-hour total. It is narrower in scope than the combined map but more precise in timing, and it includes the hourly bucket readings directly rather than the summarized daily totals. Chapter 4 covers this in more detail under the Apps section.
What “Current” Actually Means on the IEM
One subtle but important point about the IEM’s current conditions tools: observation age varies by network, and not everything labeled “current” is equally fresh.
ASOS stations report every hour at minimum, with special observations triggered by significant changes in conditions. The data reaches the IEM within minutes of the observation time for most stations. When you load the ASOS sortable currents table, the observations you see are typically less than an hour old, and often much less.
COOP observations are once-daily by design. The “current” COOP display shows the most recent morning report, which was probably submitted between 6 and 8 AM local time. Mid-afternoon, that observation is six to eight hours old. During an active precipitation event, the COOP numbers you see are not telling you what is happening right now — they are telling you what accumulated since the previous morning.
DCP river gauge data varies by station and reporting interval. Most gauges report every hour or every few hours. During flood events, reporting may intensify. But some gauges have longer reporting intervals or telemetry delays, so a “current” stage reading on the DCP map might be two to four hours old.
RWIS stations generally report every 20 minutes or every hour, with variation by state DOT configuration.
The IEM does display observation timestamps alongside each reading, so you can always check how old a value is. But knowing the typical reporting cadence for each network helps you interpret the current display correctly, especially during rapidly evolving weather situations.