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In Brief:
A ripple in the upper level flow will kick off showers Monday afternoon with a few rumbles of thunder possible. We warm up and dry out wonderfully until a significant trough arrives Wednesday PM bringing rain back to the state. Cold air pours into the system on Thursday and another good hit of snow is possible Thursday into Thursday night. The weekend weather snaps temperatures back to 'warm' levels with dry conditions.
Update 4/1 8am:
We can refine our forecast pretty well for the Thursday storm now that we've arrived at Wednesday. The chance of rain showers Wednesday afternoon/evening are lower than predicted a couple of days ago as the storm system has slowed a bit. The cold front won't arrive until Wednesday evening (Figure 1 udpate). We should see snow and snow showers most of the day Thursday (with some snow then rain showers Friday and (lesser) Saturday).
The jet stream will be contributing to the atmospheric uplift this time. We are expecting banded snow patterns. Longmont should receive 1-3 inches of snow (Figure 2 update) BUT if a band sets up over Boulder county - we could see that double. There will be snow winners and snow losers in our Thursday storm.
End update 4/1 8am
Forecast Discussion:
A short wave in the upper atmosphere is passing Monday. This is visible as enhanced/cold upper level clouds in Figure 1. Some showers are possible into the evening Monday. The SPC shows us that the cold air aloft could create enough instability for a few thunderstorms Monday (Figure 2). Later Monday - the trough (red line over eastern Colorado - Figure 3) is moving on to the east. The best chance of showers is in the afternoon (with peak daytime heating - Figure 4). That ridge behind the mini-trough moves in and we warm to the upper 60'sF to almost 70F Tuesday and Wednesday. Beautiful again (Figure 6).
The Longer Range Forecast:
The next big story is coming in the form of a big wave and cold air that will pour out of the arctic (most of it remaining to our north and northeast this week - Figure 7). The weatherunderground model shows rainfall chances increasing midday Wednesday into Thursday morning (Figure 4). The GFS is really hopping onboard with this storm Wednesday afternoon to Friday morning (Figure 5). Note that temperatures drop below and hover near freezing Friday and Saturday morning (Figure 5).
The GFS gives us an impressive 5-6 inches of snow by Saturday midday (Figure 8).
The GEM is similar but a bit below that at 3-4 inches (Figure 9).
The total amount of water we may get seems to be in the 0.5 to 0.75 inch area (Figure 10).
Note, this is the 4th Friday-ish snow/rain cold snap we've had (starting with the Friday the 13th storm that gave us some snow). That happens, sometimes... the atmosphere settles into a 1 week long repeating pattern. Interesting!
