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In Brief:
Beautiful warm weather is the only story through Monday. Then a trough and cold front move in. We cool 20-30F starting Tuesday and rain (and possible snow) continues off through next weekend - and beyond.
Forecast Discussion:
High pressure at the surface (Figure 1) and a ridge aloft (not shown) mean mostly clear skies and warm temperatures in the 70'sF this weekend (Figure 2). This is an excellent time to get out and play.
The Longer Range Forecast:
As advertised for days now, a strong cold front (blue front line in Figure 2) arrives Monday afternoon/evening. The trough is so large that it has other troughs in it (Figure 3). This is a big, slow-to-change pattern change. Temperatures drop and mountain snows resume. Higher elevations will see a foot or more before next weekend.
From Tuesday to Sunday, the weatherunderground.com model (Figure 2) gives Longmont about 2 1/4 inches of rain. The GFS (Figure 4) now gives us 2 inches (a big jump up again after yesterday's run, more like the output a day before). The GFS still doesn't give us snow, but the GEM still has about 1-2 inches over this time period (not shown). We'll keep tracking rain and snow totals as the weekend passes.
