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In Brief:
With another piece of the storm passing over Colorado - an elevated chance of cold showers will continue Wednesday PM to Thursday PM. There is a chance of a rain/snow mix in the dark-time hours. The weekend looks pretty nice with seasonally warm temperatures and only a chance of afternoon showers. Some rain and cool weather returns starting Monday night (Memorial Day).
Forecast Discussion:
There is a lot of abnormally cold air stretched from southern California up to northern Minnesota (Figure 1). This region of depressed temperatures mirror the center of a double-lobed low pressure aloft dominating the West (Figure 2). As the second lobe rotates through, we will see rain chances pick up some - but only a 1/10th to maybe 1/4th inch of new water is expected (Figure 3). It might be cold enough Thursday morning and later Thursday night for snow to mix in with the rain over Longmont. It just won't end.
The Longer Range Forecast:
The ongoing showers taper off by the early pre-dawn hours Friday. We climb to 70F for Friday and the mid 70'sF by Sunday. Just afternoon thundershowers drifting off the high country are the main threat to picnics and sporting events (Figure 4). The BolderBoulder may see some drizzle and spotty rain. The better chance of thunderstorms and rain do hold off until later in the day. At the start of the race, the temperatures should be about 51F with partly cloudy skies and a 20% chance of rain.
Things do look wet and cool Monday through Wednesday morning.