What Do VCTS and VCSH Mean in a METAR?
VCTS means thunderstorms in the vicinity of the aerodrome. VCSH means showers in the vicinity. Both codes tell you that weather has been observed nearby, even when the runway itself is dry.
That last detail can catch a student pilot out. You read a METAR with good visibility, look through the clubhouse window and see sunshine on the apron. Then four letters halfway through the report tell you there is something else to consider before climbing into the aircraft.
The decoding is straightforward once you split each group into its parts. Understanding what those parts leave unsaid takes a little more thought, particularly when a shower or thunderstorm could affect your departure or return.
Contents
What does VC mean in a METAR?
VC stands for “in the vicinity”. In the standard METAR convention, this means approximately eight to 16 kilometres from the aerodrome reference point. In the nautical miles pilots use for navigation, that is roughly four to nine nautical miles.
Be careful with the units. You may see the same area described as about five to 10 miles in some decoding guides. Those are statute miles. Reading them as nautical miles would give you a different area.
The reference point belongs to the aerodrome. It is not your aircraft’s position, and the distance is not measured from whichever end of the runway you happen to be using. A weather feature in the vicinity could lie in the direction of your first turning point or close to the route you intend to use for a join.
VC is a reporting description. It supplies no recommended clearance from the weather. In particular, the outer edge of that reporting area should never become your chosen distance for avoiding a thunderstorm. Safe flight planning needs to account for the storm and its effects beyond the visible cloud.
VCTS: thunderstorms in the vicinity
Split VCTS into VC and TS. The first part tells you where the phenomenon is being reported; the second identifies a thunderstorm. The code does not mean “very cloudy with thunderstorms”, and it contains no estimate of how soon a storm might reach the aerodrome.
A nearby thunderstorm can exist while conditions at the observing point look quite reasonable. Sunshine on the windsock and a dark sky beyond the far boundary can both be part of the same weather picture. Rain at your feet is a poor test of whether a thunderstorm deserves attention.
Thunderstorms are associated with cumulonimbus clouds, coded CB in the cloud section of a METAR. Their strong vertical air movements can produce severe turbulence. Gust fronts and downdraughts can also create abrupt changes in wind, including low-level wind shear, which is especially hazardous during take-off and landing.
The VCTS group itself gives neither the storm’s bearing nor its movement. It cannot tell you whether the cell is moving away, approaching the circuit or developing into a larger area of weather. You need the wider briefing to establish that picture. A dry runway provides very little reassurance about the air a few minutes ahead.
VCSH: showers in the vicinity
VCSH combines VC with SH, the descriptor for showers. A shower is a burst of precipitation associated with convective cloud. It can have a distinct edge, leaving good visibility nearby while obscuring the landscape beneath it.
VCSH does not specify the precipitation type or intensity. It gives you no basis for deciding that the shower contains only light rain. Depending on the weather situation, showers can involve other forms of precipitation, and the code alone does not settle that question.
Compare it with SHRA, which identifies rain showers at the aerodrome. A minus sign gives -SHRA, light rain showers; a plus sign gives +SHRA, heavy rain showers. VCSH is used without that type or intensity qualification. Its lack of a plus sign does not mean that the nearby shower is gentle.
Nor does VCSH, by itself, report a thunderstorm. Showers can occur without thunder or lightning. Keep the distinction clear when decoding the report, then consider the associated cloud and forecast to understand the conditions surrounding it.
These groups become easier to remember when you connect the letters with the weather they describe. QuizAero Bitesize’s meteorology lessons can help you build that understanding alongside the other weather-reporting knowledge needed for your theory exams.
Read the weather group alongside the rest of the report
Consider this part of a METAR: 9999 VCSH SCT025. It describes prevailing visibility of at least 10 kilometres, showers in the vicinity and scattered cloud with a base 2,500 feet above aerodrome level. There is no contradiction between the good prevailing visibility and the nearby showers.
The visibility figure describes the observation at the aerodrome. It cannot promise the same view through the windscreen after you leave. A distinct rain shaft may hide the terrain along one part of your route while the airfield remains in clear air. Anyone who has watched a shower cross the far side of a valley will recognise the difference.
Now consider 9999 VCTS FEW030CB. The report includes a thunderstorm in the vicinity and a small amount of cumulonimbus cloud with a reported base of 3,000 feet above the aerodrome. FEW describes the amount of sky covered. It gives you no assurance that the cloud’s effects are slight.
Keep the height reference in mind too. A cloud base reported above aerodrome level must be related to local terrain when you assess a route. The cloud group supplies one piece of that assessment; it does not describe every ridge or valley along the way.
Cumulonimbus deserves attention whether it occupies a small or large part of the sky. The anvil may be visible from a considerable distance, but a clear view of its shape is not guaranteed. Other cloud can obscure a developing storm, and precipitation can hide what lies beyond it.
A METAR observation is only part of the briefing
Check the observation time before interpreting the codes. A METAR describes observed conditions, whereas a TAF provides a forecast for its stated period. VCTS in an observation does not, on its own, forecast that a thunderstorm will arrive over the airfield later.
Similarly, the disappearance of VC from a later report needs context. Weather may have moved or changed. You still need to consider what is happening along your route and around your intended landing time. Two successive reports can help you notice a change, but they do not show the complete track of an individual shower.
Use the aerodrome reports with the relevant area forecast and significant-weather information. Rainfall radar can help show the distribution and recent movement of precipitation, while lightning information can add evidence of thunderstorm activity. Check the timestamps: an image on a screen can look current long after the weather has moved on.
Read AUTO reports with an understanding of their limitations as well. Automated sensors sample particular locations and may have limits in identifying weather or cloud. An apparently uneventful report should not make you dismiss a threatening view outside or adverse conditions described elsewhere in the briefing.
What should a student pilot do with VCTS or VCSH?
Start by locating the weather in relation to the intended flight. For a local lesson, consider the departure direction and training area, then the route back to the circuit. For a navigation exercise, examine whether showers could obstruct the route or leave you with poor alternatives further on.
Discuss the picture with your instructor before committing to the flight. A useful conversation goes beyond whether the airfield is currently above the required visibility and cloud minima. Work through what would make you delay, where you could remain clear of adverse weather, and when you would abandon the original plan.
Think about how much your judgement depends on a gap staying open. If the flight only works while a particular shower remains in one place, the plan has very little room for change. Make an early decision while the aircraft is still parked and the choices are easy to carry out.
With VCTS, allow for thunderstorm hazards even when there is good visibility beneath or beside the cloud. Flying under a storm can expose an aircraft to dangerous turbulence and wind shear. “We can still see through it” is an observation about visibility, with no assurance about the air movements ahead.
With VCSH, pay attention to sudden reductions in visibility and the possibility that showers could prevent a comfortable VFR return. The practical response depends on the complete weather picture and your experience. The code alone supplies too little information for a sound go-or-no-go decision.
For exam preparation, keep the decoding concise: VC locates the reported weather nearby, TS identifies thunderstorms, and SH identifies showers. When briefing a flight, use that knowledge to ask where the weather is and how it could affect the journey. Four letters can be read in a second; give their implications a little longer.
QuizAero Bitesize is our online ground school, helping you connect weather codes such as VCTS and VCSH with the meteorology behind them. The video below introduces how our lessons support that understanding as you prepare for your PPL or NPPL theory exams.
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