Rain is in the Air

Altocumulus clouds at sunset in Eau Claire tonight created a beautiful mackerel sky.

Well, Eau Claire residents, I hope you had a chance to get outside today and experience some real spring weather! At 2:25 pm, we reached 45 degrees F. Even though the sun has been down for a couple hours now, we are still sitting at 38 degrees F. If your parking lot is anything like mine after the last few days, you might need to carry an extra pair of socks for your walk through your own personal pond to your car.

Temperatures today would have heated up even more, had it not been for the cloud cover throughout the day. We saw partly cloudy skies for the majority of the day, which then turned to mostly cloudy skies by late afternoon. At sunset, the sky was covered with a mackerel sky of altocumulus clouds. This type of cloud cover is a good indicator that we will see precipitation in the form of rain within the next 12 to 24 hours. In the picture above, you can see that the clouds have hard edges, as opposed to airbrushed edges. This means that the clouds are warm enough to contain water droplets, as opposed to ice crystals. Expect a chance of rain overnight and an even greater probability of rain tomorrow.

Currently in Eau Claire, the barometric pressure is 30.17 in and falling rapidly. This rapid falling of pressure is telling us that a low pressure system is moving into our area. This helps to confirm that the current mackerel sky is a precursor to rain, as precipitating weather conditions are associated with low pressure systems.

As you can see in the surface map forecast for tomorrow morning, the low pressure system moving into our area is associated with a warm front. The air will be warm enough for rain instead of snow precipitation, as was also indicated by the hard edges of the clouds tonight.

Air traveling through our area is warmer than the air traveling through a week ago because of the current jet stream. As you can see in the map below, we are no longer receiving a direct supply of cold northern air from Canada.

Right now, the wind is calm. This is true for most of Wisconsin at the moment. The wind will pick up a bit as the low pressure system moves into our area. That is why areas to the east of us are already experiencing higher winds.

The current dew point is 26 degrees F. The relative humidity is 66%, which has been rising throughout the last few hours as the coming low pressure system brings more moisture. In the water vapor map below, you can see the densely moist air mass moving across the country towards us.

Just remember to pack an umbrella if you are heading out to visit family tomorrow. Good night, Eau Claire!