Tracking cold fronts with hyperlocal weather networks in Kansas City and Dallas

Tracking cold fronts with hyperlocal weather networks in Kansas City and Dallas

June 4, 2015 1:18 pm Published by

You may have seen our Twitter post on May 4th, also known as Star Wars day, joking “May the front be with you”. There was a cold front that passed through Kansas City on the evening of May 4th, and it was one of the clearest frontal systems we’ve observed. The temperature at 5PM was above 80° Fahrenheit and in 4 hours the temperature throughout the city had dropped nearly 20°F. Usually, cold fronts are visualized alongside radar data. The fronts are drawn at the boundary where the cold air mass meets warm air.

wunderground_radar_map

This radar map shows the May 4th cold front (blue line) moving through Kansas City from the Northwest, with storm clouds (green, yellow, and orange) following. Source: Weather Underground, 7:39 PM CDT, radar data from NEXRAD and TDWR, map data from Google.

Cold fronts are often accompanied by storms, and the diagram below helps illustrate why this relationship exists. The cold, dense, fast air mass moves along the surface, pushing warmer, moist air aloft. The warm air mass rises until it reaches a level in the atmosphere cold enough to condense the moisture in the air, which then falls as rain. These storms can develop into thunderstorms, sometimes including hail, given an unstable atmosphere that leads to strong updrafts. On May 4th, the system over Kansas City was not severe; only rain fell.

colfFront_graphic

When a cold air mass moves into a region, warm air rises and creates clouds that can develop into thunderstorms.

Radar maps are great resources for weather observers and forecasters, and we also use this technology in conjunction with the data we collect. The map below shows the same May 4th front captured by our sensor network live in Kansas City. The cusp of the front is obvious as it passes from Northwest to Southeast through KC, creating a temperature differential of 15°F from one corner of the city to the other. Our data provides a precise picture of where the front is and which direction it is moving.

front_map

Temperature contours over Kansas City showing a cold front halfway through the city. These 60 seconds of data were collected at 7:29 – 7:30 PM CDT. See the animation on our reports portal!

What you see above is an average of only 60 seconds of data, and when we compile every minute of data collected over the four-hour period, we create a complete story of the front’s movement. Below is a timeline of the temperature taken every minute at every one of our weather sensors for four hours. Rows represent each of the 25 stations, ordered from Northwest location to Southeast, and although the timelines look continuous, there are discrete columns that represent the temperature measured by each station at a specific time. The color scheme matches the map above, with temperatures in the 60s displayed as green, 70s as yellow, and 80s as orange. At 5:00PM, each row records a temperature around 80°F. The stations at the top of the graphic, those close to the Northeast corner of the city, feel the cold front first, and the temperature drops to about 65°F before 6:30PM. The front passes through the city, and the temperature at each station drops, until 8:00PM when the last few stations in the Southeast corner of Kansas City record the cold front.

You can see how the cold front pushed through Kansas City by looking at the minute to minute animation on our reports portal. It’s amazing to the front progress through the city!

temp_timeline

We’ve seen the temperature fall as the cold front rolls through Kansas City, which then causes the humidity to rise. We measure relative humidity-the amount of moisture in the air as a percentage of the hypothetical moisture the air can hold based on temperature. Warm air can hold more moisture than cold air, so even though no additional water may be entering the area, humidity can skyrocket as temperature drops. In this case, rain occurred when our sensors measured over 90% humidity.

humidity_timeline

So far in May, we have seen six nearly identical events to the May 4th front. Dallas has had its fair share of storms in the past few weeks, several preceded by visually stunning cold fronts. Many conditions of these events are alike: passing Northeast to Southwest or East to West through the city, starting with a temperature in the upper 70s or lower 80s, and cooling to a temperature in the mid-60s. The May 4th front in Kansas City was the strongest front with regard to temperature change, but the fronts would often move slowly or linger over the city, while fronts we saw in Dallas passed quickly through the city. The initial relative humidity is variable between events, but all cold fronts ended with at least 90% relative humidity and rainstorms.

These are summaries of cold fronts we have observed only this May, but we have been tracking weather in Kansas City since October of last year. You can find animations of four cold fronts on our reports portal under “Data Examples”.

We track cold fronts because they often precede thunderstorms and hail. High wind speeds and large hailstones can damage property, endanger livestock, and make travelling dangerous. We have sensor networks in Kansas City and Dallas because the risk of thunderstorms is quite high, and with our data, we can analyze exactly which parts of the city are affected by wind gusts and hail.

Our data is valuable to homeowners, commercial property owners, farmers, insurers, and adjusting firms. Interested to learn more? Contact us to get a personalized tour of our data! Or just sign up for an account by June 8th and get free trial access to our reports.