How to encode a thunderstorm in an aviation observation when it begins at 1515z and ends at 1534z.

Cracking the Thunder: How to encode a thunderstorm in LAWRS observations

When a thunderstorm rolls in, timing isn’t a nice-to-have detail; it’s mission-critical. In aviation weather reporting, every second counts because decisions hinge on what the weather did, not what it might do later. That’s where the Limited Aviation Weather Reporting System (LAWRS) codes come into play. They’re compact, precise, and designed to give pilots and air traffic controllers a clear picture in a heartbeat. Today, let’s unpack a simple but essential piece: how to encode a thunderstorm that starts and finishes within the same observation window.

The gist of the code: TS with B and E

Here’s the straightforward idea. A thunderstorm is flagged with the symbol TS (or, in some contexts, a shorthand like T but with an alphabetic cue). What makes the report really precise is adding the beginning and ending times in a compact form: B for beginning, E for ending, followed by numbers that encode the times.

• The thunderstorm code for the example is TS B15 E34.

• The “B” signals when the storm began.

• The “15” that follows B represents 1515z (the start time).

• The “E” signals when the storm ended.

• The “34” that follows E represents 1534z (the end time).

In short: TS B15 E34 tells anyone reading the observation that the thunderstorm started at 1515z and ended at 1534z. It’s a clean, unambiguous snapshot of the storm’s duration, which helps pilots assess risk, flight paths, and the need for course adjustments.

Why the end time really matters

Think about it this way: a thunderstorm isn’t a static wall of weather. It’s a dynamic event that can begin, intensify, and dissipate in a matter of minutes. If you note only the start time, you leave a big blank in the story. Does the storm still have a grip on the airspace at the moment you’re reading the observation? Was it already over, or did it linger and push changes into the next leg of the flight plan?

That’s why the end time is built into the code. It answers:

• How long did the storm affect the area?

• Was the duration long enough to influence routing decisions?

• Could a flight have skirted around the core of the storm during that window?

Now, imagine four alternative encodings and why they don’t quite fit the moment you’re trying to describe.

• Option A: TSB15E34 — this is the correct encoding for a lightning-quick moment when the thunderstorm starts at 1515z and ends at 1534z. The “TS” designates thunderstorm, “B15” marks the beginning at 1515z, and “E34” marks the ending at 1534z.

• Option B: TSB15E15 — end time 1515z. That would imply the storm lasted zero minutes, which isn’t consistent with a thunderstorm that begins at 1515z and ends later.

• Option C: TSB15E00 — end time 1500z. This would place the ending before the start, which is logically impossible and would create confusion for anyone relying on the report.

• Option D: TSB15E30 — end time 1530z. This suggests the storm ended at 1530z, which is close but not the actual end time in our example. It would still communicate a different duration than the one observed.

You can see the pattern: the right choice communicates both the window (start and end) with clarity, while the others either omit the end moment or misstate it.

How the code fits into the bigger picture of LAWRS reporting

Law and order in weather reporting isn’t just about picking a symbol and a couple of numbers. It’s about consistency, readability, and quick interpretation. The TS prefix tells readers, at a glance, that the event is thunderstorm-related. The B and E markers ensure everyone knows when the event began and ended, which is priceless when you’re triangulating reports from multiple stations, radar mosaics, and pilot observations.

A quick mental model might help: picture a thunderstorm as a scene in a short play. TS is the stage direction, B marks “the curtain rises,” and E marks “the curtain falls.” The numbers are the timestamps of those two pivotal moments. When you’re working quick, you don’t want to second-guess whether the “E” refers to the end time or the event’s end of influence. The format makes it explicit.

Practical tips for encoding thunderstorms

• Always capture both the start and end times if you can. If a thunderstorm has a clear start but a clearly documented end, that end time should appear as the E component.

• Use the taut TS Bxx Exx format consistently. Consistency reduces back-and-forth reading and misinterpretation during busy moments.

• Check the observation against available radar or satellite intel if you have it. If the radar suggests the storm is ongoing past your observation window, you may need to reflect that in a follow-up report rather than force-fit an end time that isn’t accurate.

• Treat the times as a snapshot of the storm’s life during the observation window. Weather can ramp quickly; a window of minutes often matters as much as a longer span, especially near runways and busy flight corridors.

• When in doubt, communicate the most conservative interpretation. It’s better to over-state the duration a little than to undercut by recording a too-short end time.

A natural digression about related codes

Thunderstorms aren’t the only weather phenomena you’ll code in LAWRS observations. The system relies on a family of designators that signal different events—lightning, hail, heavy rain, and so on. The common thread is the same: a concise prefix that signals the event type, followed by precise start and end times. The discipline behind these codes is what keeps air traffic flowing smoothly, even when the sky isn’t playing nice. And yes, getting the timing right is a lot like timing a good joke in a crowded room: when it lands, everyone relaxes a little and moves with greater confidence.

Why this matters in real life, not just on paper

Pilots rely on weather data to plan routes, decide whether to deviate around a weather cell, and estimate fuel needs. Air traffic controllers use these observations to sequence traffic safely and efficiently. When a thunderstorm is recorded with a clear start and end time, it becomes a reliable data point that can feed into broader weather advisories, en-route weather updates, and runway wind/visibility assessments. The bottom line: precise encoding directly supports safer, smoother operations.

A few quick words on tone and clarity

If you’re reading an observation and the duration is unclear, you can feel the tension rise. The crew may need to decide whether to delay takeoff, hold, or re-route. That’s why a compact, unambiguous code matters. It reduces cognitive load for busy readers and speeds up decision-making—without sacrificing accuracy.

What to remember when you encode a thunderstorm

• TS denotes thunderstorm. The event is weather-driven and can affect multiple flight phases.

• B followed by a time marks the start. The time is presented in a convention that makes 1515z readable as “15” in this context.

• E followed by a time marks the end. Here, 34 stands for 1534z, completing the storm’s timeline in the observation.

• The full code TS B15 E34 conveys a precise start and end, leaving no guesswork about how long the storm lasted in that observation window.

A closing reflection: small codes, big clarity

It’s easy to underestimate how much a tiny code can carry. A couple of characters, a couple of numbers, and suddenly dozens of pilots and controllers share a common, instant understanding of a storm’s footprint. That shared understanding is what keeps aircraft moving safely through sometimes unpredictable skies. So next time you see a thunderstorm report coded as TS B15 E34, you’ll know exactly what it means and why it matters.

If you ever stumble on similar codes, the same rule applies: look for the event type, locate the start, and confirm the end. When those pieces fit, you’ve got a clear, dependable picture of the weather’s life in that moment. And that’s precisely what safe, efficient flight operations demand: clear communication when the atmosphere is anything but.