5 Chapter 5 — Areas: Topic Portals
The Areas menu is the IEM’s subject-matter navigation layer — not a collection of tools, but a set of entry points organized around what you are trying to do rather than what kind of data you are looking at. Where the Networks menu asks “which observing network?”, Areas asks “which topic?”: climate, archive, GIS, drought, or agriculture. Each entry in the menu opens into a substantially different part of the site, and some of them open into entire sub-systems that could support a chapter on their own. This chapter maps the territory.
The Areas menu currently has eight entries: Ag Weather/Climate Info, Archive Mainpage, Climate Mainpage, Current Mainpage, Drought, GIS Mainpage, NWS Mainpage, and Severe Weather Mainpage. Current Mainpage and Severe Weather Mainpage were covered in Chapter 3, and NWS Mainpage anchors Chapter 7. What remains — the Archive, GIS, Drought, and Ag/Climate portals — is the subject of this chapter.
The Archive Mainpage
mesonet.agron.iastate.edu/archive/
The Archive Mainpage is worth understanding as a concept before you start clicking into it. It is not primarily an interface — it is an annotated directory. The IEM uses it as a curated index of archival resources, both internal (hosted at Iowa State) and external (third-party archives the team considers worth pointing to). If you are trying to find raw historical data and you do not know whether the IEM has it, this is the place to start your search.
The Raw File Archive
The deepest layer of the IEM’s own archive is the flat-file tree at mesonet.agron.iastate.edu/archive/data/. It is organized by UTC date: /archive/data/YYYY/MM/DD/. Within each date directory are subdirectories for different data types — GIS/uscomp/ for NEXRAD composite files, GIS/sat/ for GOES satellite products, bufkit/ for model point soundings, text/ for NWS text products, and others. The directory schema is documented at mesonet.agron.iastate.edu/archive/schema.php, which is a useful reference before you start navigating the tree directly.
The raw file archive is how you get data that is not available through any download portal or API endpoint. If you want the actual NEXRAD base reflectivity composite GeoTIFF for a specific hour during a specific event, it is in here. If you want the raw METAR observations for all ASOS stations in their original text format, that is in /archive/raw/ organized by network. The trade-off is that navigating raw files requires knowing what you are looking for — there is no form to fill out, just directory trees.
For the IEM’s NEXRAD archive specifically: composite reflectivity in GIS-friendly raster format goes back to 1997, making it one of the longer continuous radar archives available at no cost. The individual station NIDS products for the seven Iowa-coverage radars (DMX, DVN, OAX, FSD, ARX, MPX, EAX) are archived back to approximately mid-2002, with base reflectivity going back further. If you need Level II (full-resolution, dual-polarization) files, those are not hosted at the IEM — you want the Amazon S3 NEXRAD Level II archive, which the Archive Mainpage links to directly.
NWS Text Products Archive
The IEM archives an enormous volume of NWS text products — essentially everything transmitted on NOAAPORT going back to the mid-2000s. The dedicated text archive is covered in depth in Chapter 7, but the Archive Mainpage links to it and serves as the entry point for users who arrive from the “what historical data exists” direction. Key things the text archive contains: AFDs, LSRs, CLIs, CFRs, METs, TAFs, hydrologic text products, and the full record of watches, warnings, and advisories. All of it is searchable by AWIPS identifier (PIL), WFO, and date.
BUFKIT and Sounding Archives
The Archive Mainpage lists two sounding-related resources worth knowing about. BUFKIT point sounding archives for Iowa locations (and later for many more sites via MTarchive) start from January 2006 and run through the present via mtarchive.geol.iastate.edu. MTarchive, maintained at Iowa State’s geology department, is a companion archive that holds model data (GFS, NAM, RAP, RUC, ETA going back to 2001 for some products) in GEMPAK format. If you work with BUFKIT for model sounding analysis, MTarchive is the source you want for anything before the current operational archive.
The IEM’s own sounding archive for upper-air RAOB data lives at mesonet.agron.iastate.edu/archive/raob/, with a listing interface at /archive/raob/list.phtml. The RAOB archive will be covered more thoroughly in Chapter 6 under Datasets, but it belongs in the archive discussion as one of the IEM’s genuinely deep historical resources.
What the Archive Mainpage Links Out To
One of the more useful things about this page is its curated list of external archives. The IEM has no interest in reinventing resources that already exist elsewhere — the Archive Mainpage is honest about what is better found at NOAA, NCEI, Unidata, or elsewhere. Current external links include the USGS Instantaneous Data Archive (historical river gauge records), the NOAA NOMADS model data archive, the WPC daily weather map archive going back to 1872, and NCEI’s severe weather data inventory. These links are maintained by the IEM team and, unlike a general web search, represent resources they have personally used and found reliable.
The GIS Mainpage
mesonet.agron.iastate.edu/GIS/
The GIS Mainpage is the hub for spatial data services at the IEM. If you work with any GIS platform — QGIS, ArcGIS, Google Earth, Gibson Ridge, or anything that can consume WMS, WFS, or TMS layers — this is where you find out what the IEM can feed into it. The page is organized around a simple premise: the IEM handles a lot of spatially referenced data, and most of that data can be served in standard GIS formats rather than proprietary ones.
NEXRAD Mosaics: The IEM’s Biggest GIS Product
The single highest-traffic GIS product the IEM produces is its NEXRAD composite mosaic. The IEM has been generating GIS-friendly radar mosaics since 2003 — first the 4-bit N0R product, then the 8-bit N0Q composite added in 2010 when the NWS moved to higher-resolution imagery. The current operational mosaic uses N0Q (base reflectivity) and is available in multiple formats: as static GeoTIFFs in the archive tree, as WMS (Web Map Service) layers at mesonet.agron.iastate.edu/cgi-bin/wms/nexrad/n0q.cgi, and as TMS tiles suitable for slippy-map web applications.
The temporal WMS endpoints are particularly powerful: the Historical CONUS NEXRAD Base Reflectivity WMS-T service lets a WMS client request any archived radar composite back to 1997 by specifying a timestamp in the request. For a GIS user doing post-event analysis, this means you can overlay archived radar data on any spatial context — county polygons, road networks, station locations, warning polygons — without downloading and processing raw files. The IEM’s NEXRAD mosaic documentation at mesonet.agron.iastate.edu/docs/nexrad_mosaic/ explains the production chain, the color tables, and the limitations of each product version.
The RadView application at /GIS/radview.phtml is the older interface for accessing NEXRAD data in GIS format — it predates IEM One and Time Machine and serves primarily as a reference page for the WMS endpoint URLs and TMS tile server addresses. If you want to configure a GIS client to consume live or archived IEM radar, this is where you find the connection strings.
GOES Satellite GIS Products
The IEM processes GOES-East imagery from the GOES-R/S series into GIS-ready formats. The GOES products page at /GIS/goes.phtml documents the current product suite: the imagery is sourced from Unidata NIMAGE products, stored in a geostationary satellite projection, and served as WMS layers. All 16 GOES-East channels are available, both for CONUS and sector views, via the WMS at https://mesonet.agron.iastate.edu/cgi-bin/wms/goes_east.cgi. The same structure exists for GOES-West.
The GOES archive is organized by UTC date in the same flat-file tree as the radar archive: /archive/data/YYYY/MM/DD/GIS/sat/. Today’s satellite files are accessible from the GOES products page with the path pattern documented there. For anyone doing multi-source overlay analysis — radar, satellite, surface observations, and warning polygons simultaneously in a GIS — the IEM’s combination of archived products accessible via standard OGC services is genuinely hard to match elsewhere.
The RadMap API
mesonet.agron.iastate.edu/GIS/radmap_api.phtml
The RadMap API is one of the IEM’s more remarkable hidden tools. It is a map-generation service that takes a URL with parameters describing what you want — a geographic bounding box, a timestamp, and a set of layers — and returns a rendered map image. The layers available include NEXRAD reflectivity, NWS warning polygons (current and archived storm-based warnings), SPC watches, county outlines, state outlines, and CWAS.
A RadMap URL looks like this:
https://mesonet.agron.iastate.edu/GIS/radmap.php?
ts=20241115_1930&
width=640&height=480&
tz=EST&
bbox=-80.5,39.5,-75.5,42.5&
layers[]=uscounties&
layers[]=nexrad&
layers[]=sbwThat URL would produce a 640×480 map of the central Pennsylvania region at 7:30 PM Eastern on November 15, 2024, showing county boundaries, NEXRAD composite reflectivity, and storm-based warning polygons — as a static PNG, directly embeddable in a forum post or web page. For the mid-Atlantic region, the bounding box above covers essentially everything from the Harrisburg CTP WFO’s area.
This is the tool that enables the animated radar loops embedded in many weather forum posts. The IEM Radar Warnings page in the GIS section generates these loops at user-specified bounding boxes and time ranges, producing animated GIFs directly. The interface for this is at /GIS/apps/rview/warnings.phtml.
GIS Data Downloads
Beyond the live services, the GIS section offers several download products worth knowing about:
GeoTIFF rasters — archived radar and analysis products in GeoTIFF format are accessible from /GIS/tiff and via the rasters page at /GIS/rasters.php. The metadata on how to interpret the raster values (the lookup tables for converting pixel values to dBZ for radar, or to temperature units for analysis products) is documented at the Raster Lookup Tables page linked from the GIS mainpage.
COOP GIS applications — the /GIS/apps/coop/ sub-section contains duration plot applications that generate maps of COOP-derived statistics for user-specified date ranges. You select a state, a variable (temperature, precipitation), a start and end date, and the application computes the period totals for all stations in the network and produces both a rendered map and a GIS-importable CSV of station values. This is a direct path to getting spatially organized COOP summary statistics without touching the download portals.
Freeze and Warning viewers — the Freeze Map at /GIS/apps/iem/freeze.phtml maps the current freeze status and first/last freeze date observations across the ASOS network, useful in the shoulder seasons. The Warnings Viewer at /GIS/apps/rview/warnings.phtml and Watches Viewer at /GIS/apps/rview/watch.phtml are the interactive map-based alternatives to the VTEC browser covered in Chapter 7, useful when you want a visual map interface rather than a search form.
NEXRAD by Year — /GIS/rad-by-year-fe.phtml lets you compare radar mosaics for the same geographic area and same clock time across multiple years simultaneously. Want to see what the composite reflectivity looked like at 6 PM on November 15 across the last twenty years? This is the tool. It is more specialized than Time Machine but produces a more direct visual comparison of the same meteorological setup across years.
Drought Monitoring
The IEM’s Drought Monitoring portal is a focused section rather than a large tool suite. Its primary function is to provide access to US Drought Monitor data — the weekly classification maps that categorize drought severity from D0 (Abnormally Dry) through D4 (Exceptional Drought) — in formats and contexts the IEM can connect to its own observational data.
The USDM is produced jointly by the National Drought Mitigation Center, NOAA, and the USDA, and is released every Thursday. The IEM archives these releases and provides GIS download access to current and historical shapefiles. The current Drought Monitor layer is also available as a WMS endpoint for GIS integration — useful when you want to overlay drought classification on the same map as station observations or radar.
The IEM’s value-add here is primarily contextual: placing drought classification alongside the same station’s precipitation record, CDD/HDD tallies, and departure-from-normal data that live in the same system. An Autoplot chart showing a station’s year-to-date precipitation departure against the weekly drought classification trend is the kind of combined view that requires no special API work — you can produce it by combining Autoplot chart q=172 (YTD precipitation) with drought awareness from this portal.
Ag Weather/Climate Info
mesonet.agron.iastate.edu/agweather/
The Ag Weather section is where the IEM’s Iowa State roots show most clearly. A significant fraction of the site’s funding and operational rationale comes from agricultural applications, and this section reflects that. But even if you have no interest in corn or soybeans, the Ag Weather and AgClimate sections contain tools that are genuinely useful for any weather analyst who cares about soil conditions, phenology, or growing-season climate analysis.
The ISU AgClimate Network
The core of this section is the Iowa State University Agricultural Climate Network, a set of automated weather stations at Iowa State research farms that have been operating since 1986. The AgClimate stations are full-featured: they measure standard atmospheric variables plus soil temperature at multiple depths (2-inch, 4-inch, 8-inch, and deeper at some sites) and volumetric soil moisture. The data is available in daily and hourly formats going back to the network’s inception.
For a weather enthusiast, the soil temperature data is the most useful variable here. First and last freeze probability is one application — but more interesting for mesoscale analysis is how soil temperature modulates sensible heat flux and influences the surface energy budget during spring and fall transitions. The 4-inch soil temperature in particular tracks the transition between frozen and thawed soil with a lag that is valuable for interpreting precipitation type and snowmelt timing.
The AgClimate data download is at mesonet.agron.iastate.edu/agclimate/hist/dailyRequest.php for daily summaries and /agclimate/hist/hourlyRequest.php for hourly. Coverage is Iowa-focused; these stations are not spread across Pennsylvania. But the methodology and data structure are the same as what you would want if your state had a comparable network.
Soil Temperature Maps and Probabilities
The soil temperature display maps at /agclimate/soilt.php show current observations across the AgClimate network for any selected depth. The soil temperature probability tool at /agclimate/soilt-prob.php lets you ask when a station’s soil temperature at a given depth has historically reached a given threshold — useful for phenology questions like when to expect the first significant thaw at root depth or when late-season soil cooling drops below 40°F. The soil moisture time series application at /agclimate/smts.php provides the volumetric moisture data across the network for any date range.
The Broader Ag Weather Portal
The Ag Weather entry in the Areas menu leads to /agweather/, which is a portal page linking to several additional resources: the pest forecasting and GDD maps covered in Chapter 4, the evapotranspiration analysis, and the ISUSM (ISU Soil Moisture) network metadata. For users primarily interested in Pennsylvania weather, most of these resources are Iowa-specific in their observational depth but the conceptual framework — and the Autoplot charts that draw on AgClimate variables — works wherever the underlying data exists.
What to Watch Out For
The Archive raw file tree is not a backup for disappeared portal data. If a specific observation does not appear in a download portal result, it is not necessarily in the raw file archive either. The raw files represent the IEM’s original ingest stream, which has had gaps and processing failures over the years just like any operational system. The absence of data in a portal is not always resolvable by going to the raw archive — sometimes the data simply was not ingested.
GIS services have no SLA. The IEM’s WMS and TMS services are provided without warranty and have changed over the years. The N0R mosaic WMS, for example, was updated when the IEM transitioned from N0R to N0Q in 2021. If you build a workflow against one of these endpoints and it breaks, the RadMap API documentation and the NEXRAD mosaic documentation page are the first places to check for what changed.
The AgClimate archive starts in 1986 — but not all stations do. The Iowa State soil moisture network has grown over time. If you are building a long climatological analysis on soil temperature, check when each station’s record actually starts rather than assuming the full 1986-present span. The metadata page at /agclimate/info.phtml lists the active stations and their archive start dates.
The Drought Monitor section does not contain real-time station data. The drought classification is updated weekly and represents an expert synthesis, not an automated product. Do not expect it to reflect last night’s rainfall; the USDM process has a deliberate lag built in.