Tuesday will bring a strong cold frontal passage in the the Midwest. Here's a forecast map of the surface temperature anomaly on Tuesday afternoon where the frontal boundary across Missouri and Illinois is very obvious. Let's predict the Tmax for Springfield, where the main challenge is to decide how warm you think it can get before the cold front passes.
Question: Looking at temperature changes is one way to see where a front is. What is another good way -- what other atmospheric variable will usually clearly show where a front is located?
In Springfield on Tuesday, the cold front finally passed through between 2 and 3 pm local time. Despite, fog, rain and overcast skies, the temperature was able to reach 66 F before then, warmer than all of the MOS forecasts.
Answer: Between 2 and 3 pm, the temperature dropped 15 F in one hour, so that is obviously a clear indication of the frontal passage. But the wind is another variable that usually identifies the front -- the wind shifted from southwest at 17 mph to northwest at 17 mph, showing that Springfield changed from the warm to the cold air mass.
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