Weather Monitor - Help
How to use the Weather Monitor and Compact View.
Data source & refresh rate
METAR and TAF data are sourced from the Aviation Weather Center (AWC) API and proxied through this server to avoid browser CORS restrictions. Both products are fetched simultaneously on each refresh cycle.
The monitor refreshes automatically every 60 seconds. The countdown to the next refresh is visible in the status bar and in the Compact View header.
Adding stations to the monitor
Enter a 4-letter ICAO identifier in the input field and use one of the following actions:
- Add
- Permanently adds the station to your watch list. It persists across page reloads and is shared between the main view and Compact View.
- Quick Look
- Fetches the current METAR and TAF for the station and shows them in a modal without adding it to your monitor. Useful for a one-off check.
Airline presets let you load a curated set of hub airports for major US carriers in one click. Select a carrier from the dropdown to replace your current list.
Remove individual stations by clicking the on their chip. Reset Defaults restores the default hub set. Clear All removes every station.
Main view - weather cards
Each monitored station is displayed as a card showing its current METAR and TAF. Here is an annotated example:
KJFK 121530Z 04018G28KT 1 1/4SM TSRA BKN008 OVC015 14/12 A2982 RMK AO2
KJFK 121130Z 1212/1318 04015KT 5SM TSRA OVC010
FM121800 06012KT 6SM -RA BKN020
TEMPO 1220/1224 3SM FZRA OVC008
FM130000 08008KT P6SM FEW040
- Drag handle
- Drag the card to reorder your monitor. The new order is saved automatically.
- ICAO identifier & station name
- The station's 4-letter ICAO code and airport name as returned by the AWC API.
- Updated indicator (amber checkmark)
- An amber outline checkmark button appears in the card header when the METAR text has changed since the previous fetch, and the whole card pulses with an amber glow. Click the checkmark to mark the card as read (or click the card, or use Mark All Read).
- Flight category badge IFR
- Derived from the current visibility and ceiling in the METAR. See Flight category colors below.
- Observation time (e.g. 12/1530Z)
- UTC date and time of the METAR observation, in DD/HHMMz format. Shown in red when the observation is more than 1 hour old.
- METAR section
- The full raw METAR text. Hazardous weather tokens are color-highlighted - see Hazardous weather highlighting.
- TAF section
- The full raw TAF, formatted with line breaks before each forecast change group (FM, TEMPO, BECMG, PROB). Hazardous tokens are highlighted here too. Shows "Not available" when no TAF is issued for that station.
Click anywhere on a card (except the drag handle) to open a modal showing the METAR and TAF for that station. This is also what Quick Look uses.
Flight category colors
Flight category is derived from the visibility and ceiling in the METAR text using standard FAA definitions:
| Category | Ceiling | Visibility | Color |
|---|---|---|---|
| VFR | > 3,000 ft | > 5 SM | Green |
| MVFR | 1,000 – 3,000 ft | 3 – 5 SM | Blue |
| IFR | 500 – 999 ft | 1 – 2¾ SM | Red |
| LIFR | < 500 ft | < 1 SM | Purple |
The category uses the worse of ceiling or visibility. In the Compact View, the station's ICAO identifier is also tinted to match the category. CAVOK in the METAR text is treated as VFR.
Hazardous weather highlighting
Both the METAR and TAF text are scanned token-by-token. Significant weather phenomena, low visibility, low ceilings, and strong winds are highlighted automatically:
| Color | What it flags |
|---|---|
| Red - Severe | Thunderstorms (TS, TSRA, TSGR, +TSRA, VCTS, etc.), funnel cloud / tornado (FC), large hail (GR), volcanic ash (VA), sandstorm / duststorm (SS, DS), TAF windshear group (WS020/...), wind speed ≥ 40 kt or gusts ≥ 35 kt, visibility < 1 SM, ceiling < 500 ft (BKN/OVC), cumulonimbus or towering cumulus layer (CB, TCU), fog (FG), vertical visibility < 500 ft (VV001–VV004), RVR < 1200 ft (e.g. R28L/0600FT) |
| Amber - Notable | Freezing precipitation or fog (FZRA, FZDZ, FZFG, FZSN), small hail / graupel (GS), squall (SQ), ice crystals (IC), ice pellets (PL, PE), heavy precipitation (+RA, +SN, +DZ, +RASN, +BLSN), wind speed 25–39 kt or gusts 25–34 kt, visibility 1–2¾ SM, ceiling 500–999 ft (BKN/OVC), vertical visibility 500–1000 ft (VV005–VV010), RVR ≥ 1200 ft (amber) or any RVR token present |
Example METAR with highlighting:
KDEN 121555Z 27032G47KT 1/2SM +TSRA VV003 10/07 A2968 RMK AO2
Gusts of 47 kt (amber) and +TSRA + VV003 (red) are each highlighted independently.
TAF formatting
Raw TAF text is delivered as a single long string. For readability, the monitor automatically inserts a line break before each forecast change group:
| Group | Meaning |
|---|---|
| FMDDHHmm | From - new forecast period |
| TEMPO | Temporary fluctuation (< 1 hour at a time) |
| BECMG | Becoming - gradual change |
| PROBnn | Probability of conditions (30 or 40) |
All other whitespace is preserved as issued.
Update alerts & stale indicators
When the METAR text changes between refreshes, the affected card pulses with an amber glow and an amber outline checkmark button appears in the header. This typically happens when a new observation is issued.
Clear an update alert in one of three ways:
- Click the checkmark button in the card header, or click the card to open the detail modal - either marks it as read.
- Click Mark All Read in the status bar to clear all alerts at once.
- In the Compact View, click the dismiss button that appears on updated rows, or click anywhere on the row to expand the TAF (which also marks it as read).
Stale observations - if a METAR observation time is more than 1 hour old, the observation time is shown in red and the METAR text is dimmed. This is based on the observation timestamp in the data, not the time of the last API fetch.
Compact View
The Compact View is a wide, dark-themed window that shows all monitored stations in a dense list - one row per station - with the full raw METAR text visible inline. Open it from the status bar by clicking Compact View.
It opens as a separate popup window (approximately 1200 × 800 px). This wider format is intended to show the full METAR text without truncation while keeping the window easily dockable alongside other applications.
Key differences from the main view:
- One row per station - METAR text is shown inline, no separate METAR section.
- TAF on demand - click a row to expand the TAF directly below it. Click again (or the in the panel) to close. If a TAF is available a TAF indicator appears on the right side of the row.
- Dark theme - lower visual weight for secondary-monitor or side-panel use.
- Live Zulu clock - ticks every second in the header.
- Shared station list - reads and watches the same localStorage key as the main page. Changes made on the main page are reflected immediately.
- Adjustable text size - a Text Size control at the top of the Settings popup steps the list text through five scale levels; the choice is saved in your browser.
- Alerts on update - a browser notification fires and the tab title gains a
(!)prefix when a METAR changes. Clicking the notification brings the window to the front - see Browser notifications.
Compact View - UI elements
KJFK 121530Z 04018G28KT 1 1/4SM TSRA BKN008 OVC015 14/12 A2982
KATL 121525Z 27010KT P6SM FEW045 25/12 A3010
KSEA 120455Z 21008KT 4SM -RA BKN025 OVC060 12/09 A2995
- Live dot
- Pulses green to confirm the monitor is active and connected.
- HHMM/SS Zulu clock
- Live UTC clock in HHMM/SS format. Ticks every second.
- Refresh countdown
- Seconds remaining until the next automatic refresh. Click the button to refresh immediately.
- Settings button
- Opens a settings popup with a Text Size control (A− / A+, five scale levels, saved in your browser) and an Unread Highlighting toggle at the top, followed by a Monitored Stations section to add, remove, or reorder stations without leaving the Compact View. Uses the same station list as the main page. Click anywhere outside the popup to close it.
- Help button
- Opens the Weather Monitor help page in a new window.
- ICAO identifier (color-coded)
- Color matches the current flight category: green = VFR, blue = MVFR, red = IFR, purple = LIFR. White = no data or unknown.
- Inline METAR text
- The full raw METAR. Severe and notable weather tokens are highlighted exactly as in the main view. Text is dimmed when the observation is stale (> 1 hour old).
- TAF / TAF toggle
- Shown on the right when a TAF is available for the station. Click anywhere on the row to expand the TAF panel below the row. Click again or the in the panel to close it. Opening the TAF panel also marks the row as read if it was showing an update alert.
- UPDATED 1530Z badge
- Appears between the ICAO identifier and the METAR text when the METAR has changed since the last read, showing the new observation time. The row also gets a subtle amber left border and background tint.
- Dismiss button
- Appears next to the UPDATED badge. Click it to mark that station as read without opening the TAF panel.
- Flight category badge
- VFR / MVFR / IFR / LIFR label, color-coded to match the category.
- Observation time
- UTC time of the METAR observation in HHmmZ format (e.g. 1530Z). Shown in red bold when the observation is more than 1 hour old.
- Mark All Read
- Appears in the header when any station has an unread update. Clears all UPDATED badges at once.
- FAA Data Health footer
- A fixed bar at the bottom of the Compact View. Shows a status dot for the Aviation Weather Center data source (green = OK, amber = fetching, red = error) and displays the last successful fetch time on the right (e.g. Updated 1542Z).
Browser notifications
The Compact View can send an OS-level browser notification whenever a METAR changes on a background refresh - useful when the window is behind other applications or minimised.
Enabling notifications
Click the bell button in the Compact View header to trigger the browser permission prompt. Once granted, the bell disappears and notifications are active for that browser and domain.
If you previously denied permission, the bell changes to a bell-slash in red. To re-enable, open your browser's site settings for this page and set Notifications to Allow, then reload the Compact View.
What the notification shows
When METARs change the notification title reads Weather Monitor. The body lists the stations that updated:
METAR update: KATL, KJFK, KBOS
Clicking the notification brings the Compact View window to the front and dismisses the notification. Notifications auto-dismiss after 60 seconds if not clicked. If multiple refreshes detect changes before you acknowledge, the previous notification is replaced rather than stacked.
Tab title alert
As a fallback that requires no permissions, the browser tab and taskbar title gains a (!) prefix (e.g. (!) Weather Monitor - Dispatch Tools) whenever new METARs are detected. The prefix clears when you click into the Compact View window or click Mark All Read.