Back to the Basics… Current Conditions

Reading METARs is a lost art, going the way of playing an instrument, reading a newspaper or calling 411 for information. Sure many folks still play musical instruments. A lot of people still read newspapers, but I bet you’ll be hard pressed to find a paper that has sustained increased circulation over the past few years… Then there is dialing 4-1-1 for information, which I haven’t done since I was a child and for all I know the service may no longer exist…

When I started learning to fly, learning to decipher weather was like right of passage into the pilot community. When as I was a flight instructor weather “apps” or sites like PilotGEEK came along which provided the weather in real-time, plain language, making it very easy to see what the weather was ‘doing’ based on a simple coloration scheme of the information.

Photo May 11, 8 22 02 PM

The way ForeFlight lays out the information from a METAR conditions report makes it very easy to understand the local weather.

Now a days I open the familiar ForeFlight app on my iPhone and select an airport from my favorites and and then select METAR at the bottom of the screen. To ForeFlight’s credit at the very top of the METAR page is a colored dot along with a label of VFR (visual flight rules), MVFR (marginal visual flight rules) or IFR (instrument flight rules), providing a quick check of the current conditions along with a time stamps for when this information was updated. Then in the color coordinated with the flight rules (green for VFR, blue for MVFR and red for IFR) is the METAR report. This area of the screen is a small piece of real estate, the majority of the screen is the plain text list of each item from the METAR listed out in plain English, making it easy to read and understand.

The advantage to this, is that METARs are essentially always available in plain English. As a result, learning to read the abbreviations and METAR lingo isn’t as necessary, but this presentation makes it easy for students to pick up the MTEAR lingo. Everything is displayed on one page and after enough time of looking at the two versions next to one another, it becomes easy to recall exactly what the abbreviations mean.

But this is back to basics, so let’s take a look at the components of a METAR and what exactly they represent, and also what we can discern from the information. A METAR provides a total picture everything happening at that exact location.

Regardless of whether you decipher a METAR on your own or “cheat” and read the plain English version, it is crucial to remember that METAR is a snapshot of current conditions, a “now-cast,” not a forecast, as an aviation professor of mine used to say…

So, where can you find METARs if you don’t have ForeFlight? The best source is to go right to the National Weather Service. A search box will be provided, you can enter the airport/station identifier for the locations you’d leak to view METARs for. A little hint, enter the ‘@’ symbol followed by the two letter abbreviation for a particular state and you’ll be provided the METARs for all station within that state. So if I had a ton of extra time, I could search ‘@FL’ to see all of the current condition reports for the state of Florida…

Let’s take a look at a couple of reports:

KLAF 071854Z 34013G17KT 10SM FEW036 SCT095 BKN110 16/09 A2979 RMK AO2 PK WND 33026/1814 SLP085 T01560089

KLAF – This is the station identifier, KLAF for example is the airport in West Lafayette, Indiana, the home of Purdue Aviation.

071854Z – The station identifier is followed by the date and time information for the report. This report was made on the 7th day of the month at 1845 Zulu time.

34013G17KT – Next comes the wind information. The wind during this report was from 340 degrees at 13 knots of sustained wind, with gusts up to 17 knots. Remember, when it comes to wind, the written word is true, so when it comes to cross wind component calculations, remember the magnetic variation! 

10SM – Visibility comes next, reported in statue miles and typically up to 10 miles, so a 10SM report could be for 10 miles of visibility all the way up to unlimited… Occasionally you’ll see military control towers (or joint use), issue reports of 15 miles of visibility.

FEW036 SCT095 BKN110 – Cloud information follows and this is reported in elevations Above Ground Level (AGL). For this report there were clouds (few in density) at 3,600 feet AGL, clouds (scattered in density) at 9,500 feet AGL and clouds (broken in density) at 11,000 feet AGL. The weather equipment which produce METAR information can only detect cloud bases so the various layers could have ample space for flight by Visual Flight Rules (VFR) between them or possibly not…

16/09 – Next is the temperature and dew point report. the first number is the current temperature reported in celsius, followed by he dew point, also reported in celsius. The proficient pilot knows that when these numbers approach one another, fog & clouds are very likely. The dew point represents the temperature at which air is saturated, so it makes sense that when the sun goes down in the spring time that as the temperature decreases and approaches the dew point, you might see fog. Note: negative values are preceded by the letter “M”.

A2979 – The final main piece of the report is the altimeter setting. The air pressure is reported in inches of mercury, convent enough for you to program into your altimeter by use of the Kollsman window, named for Mrs. Kollsman’s husband (as someone I taught a lot of ground schools with used to joke…)

RMK – This abbreviation for remarks shows where the remark information (additional in nature) begins.

AO2 – This item identifies the type of reporting equipment used, A02 stands for an automated system with a precipitation sensor.

PK WND 33026/1814 – This item identifies the peak wind condition since the last report. The particular observation shows a peak wind from 330 degrees at 26 knots, which occurred at 1814 Zulu time.

SLP085 – Next is the Sea Level Pressure, reported in hectopascals. 

T01560089 – This item highlights the specific temperature and dew point, previously you saw 16/09 reported. This item takes the report to a more exact level, showing the temperature as 15.6, which rounded to 16 and 8.9 which rounded to 9.

Now let’s take a look at a couple of other items that can show up in a METAR… KHHG 071855Z AUTO 28011G18KT 260V330 10SM BKN034 BKN110 A2969 RMK AO2. This report includes an item, “260V330“. This value is a modifier to the wind report and means that the wind is variable between the headings of 260 degrees and 330 degrees.

KHUF 071908Z 29009KT 10SM VCTS -RA FEW048 FEW070 OVC095 19/16 A2985 RMK AO2 LTG DSNT E TSE02 PRESRR P0000 T01940161. This report includes “VCTS -RA”, which stands for vicinity thunderstorms, meaning thunderstorms exist within 10 miles, but not less than five miles form the station. Additionally there is rain, light in intensity, if the intensity was average there would be no preceding symbol and if the rain was intense in nature, there would be a + symbol preceding the RA item. You will also note that there is an extra component to the remarks section, “LTG DSNT E TSE02”. This items reads, lighting distant East and Thundershowers ended 2 minutes past the hour.

Sure there is a lot more we could cover on this topic, but we’ll save all that for another post, maybe about how the individual instruments that measure each field in the report operate…

-Fly Safe, @MTElia1B9

This post is for you Emily! All about METARs…




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