Station Models!

What is it?A station model is a symbolic illustration showing the weather occurring at a given reporting station (developed back in 1941)

These reporting stations are EVERYWHERE; they are just simply locations with instruments and equipment for measuring atmospheric conditions

Why do we use them?Easy to look at multiple weather elements in a

small space on a map for multiple locations

Internationally accepted coding system for weather

What does a station Model cover?

A LOT of things

Temperature

Cloud Cover

Precipitation Type (amount)

Visibility

Pressure trend

Wind (direction & speed)

Dew Point (F)

Pressure at sea level

Cloud Cover SymbolsThe circle in the middle depicts cloud cover.

We look at it as a percentage. If it’s 25% cloud cover outside, you fill in ¼ of the circle

VisibilityJust tells you how far you can see out (in miles) before your gaze is obstructed by fog, precipitation, atmospheric elements, etc.

*In this example, you can see clearly ½ a mile out

Current WeatherCurrent weather is depicted next to the visibility with a particular symbol (more on next slide)

*In this example it says the current weather is snow (*). This would explain why you might now be able to see too far out, b/c its snowing

Current Weather Symbols

Current Weather

Also, if there happens to be no precipitation, then you do not put anything! Leave it blank!

Wind Direction SymbolsWind is measured in knots, which is a speed equal to one nautical mile, approximately 1.151 mph

Each little marking is called a “feather”

Little feather = 5 knots

Big feather = 10 knots

Bottom triangle = 50

knots

Wind Direction Station model always describes where the wind is coming FROM

*In this example, the feathered line tells me that the wind is COMING from the south east and GOING north west.

Can you tell how fast the wind is going? 25 knots

Temperature on the modelALWAYS in degrees Fahrenheit although we DO NOT include the units

We want the simplest model possible so we just leave the unit (F) out. It’s assumed to be in degrees F

Dew PointThis is the temperature at which the air becomes saturated

This is also ALWAYS going to be in degrees F, but we don’t include the unit F

How can we look at Humidity

Humidity on a station model is not explicitly put

You can INFER it by comparing the temperature and the dew point.

- If the temp and dew point temp numbers are close together, it’s humid

- If the temp and dew point temp numbers are far apart, it is less humid/not humid

This station model shows that it is very humid where it is

PrecipitationA station model is always going to tell the amount (in inches) of precipitation that has fallen in the past 6 hours

*How much snow has fallen in this station model?

½ inch

PressurePressure is the trickiest part of a station model!!!

It is measured by a barometer, so it is called barometric pressure, the amount of pressure that the atmosphere is pushing down on the surface of the Earth

This is measured in millibars or mb

Normal Pressure?Typical pressure is going to range from about 950.0 mb to about 1040.0 mb (this is what you will usually see)

BUT these numbers are bulky on a weather station: 1040.0 mb - is bulky

So we shorten it

Shortening how we show Pressure

Example: take 1014.0 mb

- First, take away the units.

Then you get, 1014.0

- Second, drop the first number

The first number is ALWAYS either going to be a 10 or a 9. In our example, it is a 10. So drop the 10 and you get 14.0

- Third and last step, drop the decimal, and you get 140, this is what you write on your station model

Another Example to Shorten

Take 973.2 mb

Drop units – 973.2

Drop first number (this time it’s a 9 and not a 10. *Remember, its always going to be a 9 or a 10 that you drop) – 73.2

Then drop the decimal – 732

732 is what you write on

your station model !!!

Convert the Pressure from the Model

When you’re given a model and you need to find the actual pressure, you have to convert it back from the shorten number. Take this example: 196

Convert 196You’re taking the shortened version and

lengthening it

FIRST RULE, determine if your number is lower or higher than 500. If the number is less than 500, add a 10 in front of

the number. If the number is greater than 500, add a 9 in front

of the number

** In this example we are adding a 10 in front because 196 is less than 500. So it becomes 10196

Convert 196 (cont.)After you’ve added the 10 (remember we added

the 10 in front instead of a 9 because 196 is less than 500) you have 10196

Add back your decimal, which ALWAYS goes ONE space BEFORE the last number: 1019.6

Then add back your units 1019.6 mb

SOOOO, 196 is actually 1019.6 mb

Convert 675 (Example 2)So you see 675 on the station model

First step, is 675 greater or less than 500? Greater! So, add a 9 in front: 9675

Second step, add your decimal right before the last number: 967.5

Third and last step, add your units! 967.5 mb

So, 967.5 is the actual pressure that we got from the shortened version on the model

Pressure TrendRight below the pressure on the station model, you will see a pressure trend.

This tells us how much the pressure has gone UP or DOWN in the past 3 hours

We WANT to know the trend b/c that tells us what sort of weather is headed our way. Pressure going down means bad weather is approaching. Pressure going up means good weather is approaching.

Pressure Trend ExampleHow do we read it?

• This example says +19/

What that’s really telling us is that the pressure has gone up 1.9 mb in the past 3 hours (yes, you add a decimal before the last number)

Pressure Trend Example (cont.)

So, we know that the pressure in this example has gone up by 1.9 mb, but what does the + and / mean?The + just means it is going UP. If it was a – then that would mean that it is going down. The / just shows you that the trend is going up, like a mini graph line. If it was like this: \ that would mean it was going down.

Pressure Trend Example 2Let’s say you measure your pressure trend at your station and the pressure has gone down 4.5 mb, how do you show this on your station model??

First, drop the units and decimal: 45

Then add a + or - …. It’s going down so: -45

Then add your trend, either / or \, we add \ because the trend is going down so we get: -45\

More Explanation?This youtube video is great and explains what I just covered if you’d like to listen to it and gain a better understanding.

https://www.youtube.com/watch?v=h9pwdHz0S5M