After highs only in the 10s yesterday, we're going to see temperatures climb a good 20 degrees in many places as a warm front moves through Western Wisconsin. Some areas down south around La Crosse could top out in the 40s. This is some serious warm air advection.
What is warm air advection you may ask? It is when warm air is advected (or moved) by the wind to an area of cooler temperatures. The opposite is known as cold air advection. The stronger the advection...the more temperatures can change in a relatively short amount of time.
Check out this weather map below. This is temperature and wind data at one of the critical levels we look at when forecasting. It's around 2,500 feet high.
The oranges and yellows represent warmer temperatures while the blue dashed-lines represent colder temperatures. Check out Minnesota. Look how bunched up all those temperature lines are together! You go from dark oranges in the southwest corner of the states to dark blues up in the northeast corner of the state. That is a significant contrast from one end of the state to the other. That's known as a temperatures gradient, quite the large temperatures gradient at that. Also, look at the wind barb that is originating from the Twin Cities. That represents the wind speed and direction at this level over the Twin Cities. The wind barb is showing where the wind is coming from, so based on this wind barb we're seeing a 30mph wind out of the south-southwest.
Notice how the wind is blowing strongly from where we have those darker oranges straight towards the colder blues. This is an example of strong warm air advection. We have a strong temperature gradient across the upper Midwest and the winds are blowing quite strongly aloft pretty much perpendicularly to the temperature gradient. Had the winds been out of the same direction, but suppose only at 5 mph, the warm air advection wouldn't have been as strong. It would be stronger if the wind speed was stronger. What if the wind had been blowing out of the southeast, parallel to the temperature gradient, but still at 30 mph? Well, there would be no warm air advection because the warm air wouldn't be moving into the cold air region. The would be no change in temperature and we would probably be stuck in the low 20s today. Areas of temperature advection are places we can also look to find fronts. Warm air advection is associated with warm fronts, which we are seeing in today's case. Cold fronts are associated with cold air advection.
Because we are having such strong warm air advection and a warm front lifting through the region, we'll see highs today in the mid 30s close to 40 degrees in the south after starting today in the 10s. This is actually a very large swing in temperatures considering we have a snow pack on the ground. Highs will continue the warm well into the 40s on Tuesday. We remain well above normal the rest of the week, and we'll be saying goodbye to our snow pack.