WHAT ARE THE 10 SIGNS OF AN APPROACHING COLD FRONT?

Here are the top 10 signs of an approaching cold front:

WHAT ARE THE 10 SIGNS OF AN APPROACHING COLD FRONT?

1. Barometric Pressure Drop - As the cold front approaches, you will notice a steady decline in barometric pressure over several hours. Warm air is less dense than cold air, so the incoming cold air causes pressure to drop. A rapidly dropping pressure is usually the first reliable sign a cold front is near.

2. Wind Direction Shift - Keep an eye on your wind sock or out of your window. The direction the wind is blowing from will begin to shift counterclockwise as the cold front moves in. This is because the wind will transition and come from the direction of the approaching cold air mass. So if the wind was out of the south, it will start to shift to come from the west/northwest.

3. Increasing Wind Speeds - Along with the wind direction change, you'll notice the winds picking up stronger ahead of the front. This is due to the mixing of warm and cold air creating vertical winds within the frontal boundary. Gusts could be 10-20 mph stronger on average than previous winds out of the new direction.

4. Clouds Thicken and Lower - As moisture rises with the strengthening frontal winds, higher level clouds will thicken and their bases will lower closer to the ground. Cloud types may transition from fair weather cumulus to larger cumulus and towering cumulus indicating instability. Expect an overcast sky as the front passes through.

5. Showers/Thunderstorms - On warm fronts, precipitation is usually light and widespread. But cold fronts are commonly accompanied by showers and sometimes thunderstorms as instability increases within the boundary zone between warm and cold air. Strong thunderstorms can even become severe under the right conditions due to strong winds aloft. 

6. Temperature Drop - After the cold front passes completely through, temperatures will begin to fall rather rapidly typically 10-15 degrees Fahrenheit within an hour or two. This is because the source of the cold air mass is now the dominant air mass over the area with the passage of the frontal boundary. 

7. Clearing Skies - Even though clouds were thick with the approaching front, once the precipitation ends with the front's passage, skies will begin to rapidly clear out. This is due to downward motions within the drier and more stable cold air mass clearing clouds and allowing sunshine to break through again.

8. Humidity Decrease - The dew point or relative humidity levels will noticeably drop behind a cold front as well. Warm sectors ahead of fronts are generally more humid with southeast/south winds. But northerly winds behind fronts advect dry polar continental air with lower moisture levels. Skin may feel immediately less sticky.

9. Air Density Increase - Cold air is denser than warm air, so as cold air moves in, it will cause air pressure to rise back up again as the atmospheric mass over an area increases. Along with lower moisture levels, this density increase improves visibility distances by allowing light to travel further through the atmosphere. 

10. Stable Weather Pattern - In the days following a cold front passage, expect more stable weather to persist. Temperatures remain seasonably cool with less variation. Winds stay mostly out of the north. Fronts bringing sharp changes in weather will usually be followed by generally fair conditions in the wake of Arctic or Polar Continental air behind the front.

Keep an eye out for a pressure drop, wind shift, increasing winds and lowering clouds ahead of heavy rain or thunderstorms to know if a reliable cold front is pushing into your area. The passage of the front is then marked by rapidly falling temperatures, clearing skies, lower humidity, and stable post-frontal conditions behind it. Monitoring these 10 signs will help provide a good forecast of incoming cold fronts.