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Forecast Discussion:
The first cold front hit and had a period of moist uplift after its passage significant enough to drop 1/2 inch of snow on my part of town (Figure 1). I didn't directly forecast that but did show maps hinting at some minimal snow amounts near Longmont. (This post will go up early since we are mid-storm and serious cold is coming soon.)
The cold fronts will keep coming, the temperatures will keep dropping, and snow will soon coat everything. A nice period of winter returns. For today (Sunday), we are briefly between surges of moisture from the Pacific and cold front passages. We start the day dry (Figure 2).
The next period of snow begins around 6 pm today (Sunday) with snow chances fairly continuous through midday Tuesday (Figure 3). Note that the high on Monday may only be in the teens and Tuesday not much better in the lower 20's F.
This is all what a giant trough in the west does with cold Canadian air flowing south over the ridge off in the eastern Pacific (Figure 4). Ripples in the flow will bring periods of instability over the area and surges of colder and colder air. By tomorrow morning (Monday am), figure 5 shows that snowfall will be spreading over much of the state.
The longer range forecast:
The weatherunderground model in Figure 3 gives us about 2-4 inches of snow through Monday pm. The forecasters at weather5280.com's hand-drawn forecast gives us a trace to three inches (Figure 6). The GFS paints us with 1/2 to 2 inches through Monday pm (Figure 7). By 24 hours later (Figure 8) the GFS gives us 2-3 inches of snow.
Looking back on Figure 3, we warm to the 30's F on Wednesday and see a late week return of snow. More on that after the current storm plays its hand.
