First, just a quick note on day 10, which ended with a bang with
a squall line bringing a sustained wind of 39 kt and gust to 54 kt, as well as
0.60” of rain, 0.48” of that in 12 minutes.
A much cooler air mass is in place now, but the true cold air
mass is still off to the north. A secondary cold front will pass through
tomorrow evening, with sunshine for the first half of the day and westerly
winds just ahead of it likely leading to overachieving high temperatures
tomorrow. However, the cold air aloft combined with surface daytime heating
will lead to some instability, and some scattered showers will form ahead of
the cold front. Most likely, at least one of these showers will hit Des Moines,
bringing a few hundredths of an inch of rain. Also, the showers will form their
own low-level cold pockets through evaporational cooling given the dry
low-level air, leading to gust fronts that boost the winds for short periods of
time. Still, the showers are unlikely to impact the high that much as the sunshine
earlier in the day will help to warm surface temperatures near to their limit
before instability occurs. The sunshine and instability will also lead to mixing
down of stronger winds from aloft even outside of showers. Low will occur at
the end (Saturday 06z) behind the cold front as winds switch to northwesterly.
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| Source: WxChallenge |
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| Source: weather.us |
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| Source: NWS |
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| Source: PivotalWeather |
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