How thunderstorm and wind shear codes in METAR signal severe weather.

What can indicate severe weather conditions in a METAR report?

• A. The presence of "FS" (fog and smog) codes
• B. The occurrence of "TZ" (tropical zone) codes
• C. The presence of "TS" (thunderstorm) or "WS" (wind shear) codes
• D. General weather patterns over several days

Answer: (C)

In a METAR report, the presence of "TS" (thunderstorm) or "WS" (wind shear) codes signifies conditions that can indicate severe weather. Thunderstorms are often associated with intense precipitation, strong winds, and electrical activity, which can lead to hazardous conditions both on the ground and in the air. Wind shear refers to abrupt changes in wind speed and direction, which can be particularly dangerous for aircraft during takeoff and landing, contributing to turbulence and potential loss of control. The other options do not typically indicate severe weather on their own. For example, "FS" codes referring to fog and smog can certainly affect visibility but are not as directly indicative of severe weather as thunderstorms. "TZ" codes for the tropical zone also do not specifically relate to severe weather conditions, as they instead provide information about the region's climatic classification. General weather patterns over several days may suggest trends or eventual severe weather but are not specific indicators in a single METAR report. Thus, the presence of "TS" and "WS" codes is the most direct indication of severe weather conditions.

METARs are the weather snapshots pilots rely on every hour. They aren’t novels, but they tell a story—one that can help you spot dangerous weather before it reaches you or your aircraft. If you’ve ever wondered how to tell, from a lone line of letters and numbers, whether severe weather might be brewing, you’re in the right place. Let’s break down the telltale signs you’ll find in a METAR, with a sharp eye for the codes that matter most: TS for thunderstorms and WS for wind shear.

What a METAR really is—and why it matters

Think of a METAR as a weather report card for a specific airport and a precise moment in time. It gives you visibility, cloud cover, winds, temperature, dew point, and more. It’s concise, usually a single line, and it’s designed to be read at a glance. For pilots, air traffic controllers, and weather enthusiasts, METARs are the baseline you lean on when you’re planning a flight or just trying to understand how conditions might evolve.

The two codes that scream “severe weather” in a METAR

Here’s the thing: not every weather feature in a METAR signals danger. Some things affect comfort or visibility without posing real risk to flight. But two particular codes stand out when storms are near or on the way.

• TS – Thunderstorm

When you see TS in a METAR, that’s a direct hint that lightning and thunder are part of the current weather picture. Thunderstorms can bring heavy rain, strong gusty winds, hail, and sudden changes in visibility. They’re the kind of weather that can rattle the cockpit and complicate decision-making, especially if you’re close to the storm.

You’ll often see TS paired with other weather descriptors, like TSRA (thunderstorm with rain) or TSGR (thunderstorm with hail). The presence of TS is a flag you should take seriously, because it’s a sign the air around you is actively being stirred up by convective energy.

• WS – Wind Shear

Wind shear is a different beast. It’s not about how hard the wind is blowing at a single altitude; it’s about how quickly the wind speed and direction change with altitude or across a short distance. In aviation terms, wind shear can mean sudden shifts that surprise an aircraft during climb, approach, or landing. That kind of abrupt change can sap lift, buffet an airplane, and complicate keeping a stable flight path.

In METARs, WS may appear as a wind-shear indicator in the report or be noted in remarks related to the wind group. The key takeaway: wind shear doesn’t always produce visible storms, but it can create dangerous conditions for takeoff and landing. It’s the quiet danger you don’t want to miss.

Why these two codes matter more than the others

There are other weather features you’ll encounter in METARs—fog, haze, rain, snow, or mist. Some of these affect safety or comfort, sure, but TS and WS are the two that most directly point to conditions that can rapidly degrade flight performance or create hazardous flight paths.

• FS (fog and smoke) affects visibility. It’s important, especially for ground operations, but it doesn’t automatically signal the wind shifts or lightning hazards you get with storms.

• TZ (tropical zone) is more about regional climate classification than a single moment of danger. It’s interesting, but it doesn’t tell you whether severe weather is occurring now.

• General weather patterns over several hours or days can hint at trends, but METARs are snapshots. To forecast evolving hazards, you’ll combine METARs with radar, satellite, and forecast products.

Let’s look at a practical example

Imagine you’re glancing at a METAR that reads something like this (simplified for clarity):

KJFK 041651Z 27018G28KT 5SM TSRA BKN012 BKN020 22/16 A3005 RMK AO2

What jumps out?

• TSRA appears, signaling thunderstorms with rain. That’s a clear sign of convective activity—potentially strong winds, heavy rain, and thunder.

• The winds are 270 degrees at 18 knots, gusting to 28 knots. That gusty wind can be a factor for takeoff or landing if you’re near the storm’s edge.

• Cloud cover BKN012 and BKN020 tells you there are broken layers around 1,200 feet and 2,000 feet. Low, broken ceilings plus a thunderstorm in the vicinity spell trouble for radar vectors and approach paths.

• If you’re a pilot in the area, you’d want to know if you should divert, delay, or alter your approach to avoid the storm cell.

This is the core of METAR literacy: recognizing how TS and wind changes in a short time frame interact with clouds, visibility, and runway conditions. It’s not just a string of letters; it’s a map of risk.

Wind shear in practice: what to watch for

Wind shear is trickier because it isn’t always obvious from a single metric. Here are a few practical cues to consider:

• Sudden changes in wind direction or a rapid increase or decrease in wind speed within a short distance or altitude band.

• A METAR that mentions wind shear (WS) alongside STS or gusts hints at a turbulent profile that could affect climb performance or approach stability.

• In the real world, wind shear often shows up near the surface during landing and immediately after takeoff, particularly in changing weather regimes or near frontal zones.

If you’re doing hands-on work, you’ll also cross-reference METARs with terminal area forecasts (TAFs) and radar trends to see how the storm’s evolution might unfold in the next 1–2 hours. It’s a bit like weather sleuthing—spotting the hints, connecting the dots, and anticipating what could be dangerous for flight.

More than a single line: reading METARs as a story

Here’s a friendly reminder: METARs are not standalone puzzles. They’re tiny chapters in a larger weather narrative. You read one line, then you check the radar, then you compare with the latest radar mosaics, satellite imagery, and weather conversations among pilots and controllers. The real skill is in synthesis—knowing when a TS in a METAR translates into a storm warning for a given runway, or how wind shear could affect the takeoff distance you’re planning.

A few quick moves to sharpen your eye

If you want a practical habit to keep your METAR reading sharp, try these:

• Scan for the TS or WS flags first, then read the rest of the line for context. If you see TS, your awareness should rise immediately.

• Check for accompanying elements like TSRA (thunderstorm with rain) or BKN/OVC ceilings. Storms often come with rough weather that reduces visibility and raises turbulence.

• Note wind patterns. A gusty wind with a high gust factor signals wind shifts that can complicate approach and departure.

• Pair METAR data with live radar when possible. The combination of a thunderstorm tag and real-time storm echoes is a strong predictor of hazardous conditions near airports.

• Use reliable sources to verify the report. The aviation weather ecosystem—including the Aviation Weather Center and national weather services—offers authoritative METAR feeds and updates.

Where you’ll see these codes in real life

If you’re curious about where to practice spotting TS and WS, you’ll find them in official METAR feeds around the world. Airports with frequent convection or strong winds are particularly informative. Tools like aviationweather.gov provide current METAR strings, while flight planning software often brings in these signals in a more visual, user-friendly way. It’s not just about decoding; it’s about building intuition—recognizing that certain patterns warn of hazards before they arrive at your door.

A light touch of tangents that matter

Weather literacy isn’t only for pilots. Ground crew, air traffic controllers, and even airport planners benefit from understanding TS and WS signals. A storm isn’t just a weather phenomenon; it’s a system that can influence runway availability, taxi routes, and maintenance windows. That’s why these codes matter beyond the cockpit. They help teams synchronize decisions, protect people, and keep operations moving with fewer surprises.

Putting it together: what to remember

• TS is your direct cue that thunderstorms are in the mix. Expect lightning, heavy rain, and gusty winds. These storms can move quickly and change the game in moments.

• WS warns about wind shear, a risk factor for climb and landing performance. It highlights the potential for abrupt wind changes that challenge control.

• Other codes—FS for fog, TZ for tropical zones, or notes about longer-term patterns—add flavor to the picture but don’t scream danger in the same urgent way as TS and WS.

• A solid approach combines METARs with radar, pilot reports, and forecast products to form a coherent picture of near-term hazards.

Final thoughts: stay curious, stay prepared

Reading a METAR is an exercise in staying alert without getting overwhelmed. It’s about training your eye to see the two big red flags—thunderstorms and wind shear—and then layering that with the rest of the weather story. The goal isn’t fear; it’s informed decision-making. When you spot TS or WS in a METAR, you’re not guessing—you’re reading conditions that can affect flight safety and operations right now.

If you’re exploring FAI-weather topics in this space, you’ll keep encountering the same principle: weather is a system, and METARs are its quick, practical snapshots. Mastering the TS and WS cues is a reliable way to connect theory with real-world aviation. And if you ever want to check how this plays out in actual data, head to trusted sources like the Aviation Weather Center or local meteorological services, where you’ll see those codes pop up in context and you’ll hear the weather telling you its immediate story.

Key takeaways, in a nutshell

• TS signals thunderstorms and their hazards—lightning, heavy rain, strong winds.

• WS signals wind shear—dangerous, rapid changes in wind that can affect takeoff and landing.

• FS, TZ, and longer-term patterns matter, but TS and WS are the most direct indicators of imminent severe weather in a METAR.

• Read METARs as a quick, practical weather snapshot, then corroborate with radar and forecasts to form a complete picture.

So, next time you glance at a METAR, scan for TS and WS first. Treat them as the weather’s loudest warnings, then fill in the rest with the details that help you understand how conditions might evolve. That’s the core habit that keeps pilots and planners safe, informed, and ready to respond.