April 24, 2018

Yet Another Beautiful Day

Current Conditions

Temperature: 48 °F
Dew Point: 36 °F
Winds: NNE 4 mph
Pressure: 1022.3 mb
Visibility: 10 miles

Today started off with clear skies and a temperature of 35 °F with no winds. As the day progressed some cirrostratus clouds moved in followed by altocumulus clouds. By early evening stratus clouds were covering portions of the skies. This progression along with the wind direction indicate a low pressure system moving in to the area. Indeed, the surface map in figure 1 shows just that.

Figure 1. Surface map of the United States.

Just to the south of Wisconsin is a low pressure system. Because winds rotate counter-clockwise around a low pressure system, the winds to the north of it come from the E/NE direction, which is exactly what Eau Claire is experiencing.
The increase in cloud cover can also be seen in the water vapor satellite image in figure 2.

Figure 2. Water vapor satellite of the United States.

In the northeast there is some light precipitation, but otherwise the country is currently looking quite in terms of weather.  However, next week we could be seeing some interesting weather. A fast-moving airstream over the United States will experience a trough over the Arizona/New Mexico also called an Omega trough. After the air comes out of the trough, it produces 'divergence aloft' which means the air is diverging from the narrow trough it came out from. This means that air can rise in the area directly below which creates storms. The increase in moisture and temperature will add to this scenario and create a severe weather risk in the southern United States (figure 3).

Figure 3. Omega trough projected for the United States next week.

Previous Prediction

Yesterday's prediction was correct; the temperature was lower and there was increased cloud cover from yesterday. There also was no precipitation.

Prediction

Surprisingly, tomorrow we should see some more clear skies. The predictive map shows the low pressure system moving out of the area and taking the cloud cover with it (figure 4). Go enjoy the sunshine while you can!

Figure 4. Predictive weather map of the United States for April 25, 2018.